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1
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Hubal A, Vendhoti A, Shaffer CN, Vos S, Corcino YL, Subauste CS. Inhibition of Src signaling induces autophagic killing of Toxoplasma gondii via PTEN-mediated deactivation of Akt. PLoS Pathog 2025; 21:e1012907. [PMID: 39869638 PMCID: PMC11801697 DOI: 10.1371/journal.ppat.1012907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2024] [Revised: 02/06/2025] [Accepted: 01/14/2025] [Indexed: 01/29/2025] Open
Abstract
The intracellular protozoan Toxoplasma gondii manipulates host cell signaling to avoid targeting by autophagosomes and lysosomal degradation. Epidermal Growth Factor Receptor (EGFR) is a mediator of this survival strategy. However, EGFR expression is limited in the brain and retina, organs affected in toxoplasmosis. This raises the possibility that T. gondii activates a signaling mechanism independently of EGFR to avoid autophagic targeting. We report T. gondii activates Src to promote parasite survival even in cells that lack EGFR. Blockade of Src triggered LC3 and LAMP-1 recruitment around the parasitophorous vacuole (PV) and parasite killing dependent on the autophagy protein, ULK1, and lysosomal enzymes. Src promoted PI3K activation and recruitment of activated Akt to the PV membrane. T. gondii promoted Src association with PTEN, and PTEN phosphorylation at Y240, S380, T382, and T383, hallmarks of an inactive PTEN conformation known to maintain Akt activation. Blockade of parasite killing was dependent of activated Akt. Src knockdown or treatment with the Src family kinase inhibitor, Saracatinib, impaired these events, leading to PTEN accumulation around the PV and a reduction in activated Akt recruitment at this site. Saracatinib treatment in mice with pre-established cerebral and ocular toxoplasmosis promoted PTEN recruitment around tachyzoites in neural tissue impairing recruitment of activated Akt, profoundly reducing parasite load and neural histopathology that were dependent of the autophagy protein, Beclin 1. Our studies uncovered an EGFR-independent pathway activated by T. gondii that enables its survival and is central to the development of neural toxoplasmosis.
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Affiliation(s)
- Alyssa Hubal
- Department of Pathology, Case Western Reserve University, Cleveland, Ohio, United States of America
- Division of Infectious Diseases and HIV Medicine, Department of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Anusha Vendhoti
- Department of Pathology, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Charles N. Shaffer
- Division of Infectious Diseases and HIV Medicine, Department of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Sarah Vos
- Division of Infectious Diseases and HIV Medicine, Department of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Yalitza Lopez Corcino
- Division of Infectious Diseases and HIV Medicine, Department of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Carlos S. Subauste
- Department of Pathology, Case Western Reserve University, Cleveland, Ohio, United States of America
- Division of Infectious Diseases and HIV Medicine, Department of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America
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2
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Langdon CG. Nuclear PTEN's Functions in Suppressing Tumorigenesis: Implications for Rare Cancers. Biomolecules 2023; 13:biom13020259. [PMID: 36830628 PMCID: PMC9953540 DOI: 10.3390/biom13020259] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 01/25/2023] [Accepted: 01/28/2023] [Indexed: 01/31/2023] Open
Abstract
Phosphatase and tensin homolog (PTEN) encodes a tumor-suppressive phosphatase with both lipid and protein phosphatase activity. The tumor-suppressive functions of PTEN are lost through a variety of mechanisms across a wide spectrum of human malignancies, including several rare cancers that affect pediatric and adult populations. Originally discovered and characterized as a negative regulator of the cytoplasmic, pro-oncogenic phosphoinositide-3-kinase (PI3K) pathway, PTEN is also localized to the nucleus where it can exert tumor-suppressive functions in a PI3K pathway-independent manner. Cancers can usurp the tumor-suppressive functions of PTEN to promote oncogenesis by disrupting homeostatic subcellular PTEN localization. The objective of this review is to describe the changes seen in PTEN subcellular localization during tumorigenesis, how PTEN enters the nucleus, and the spectrum of impacts and consequences arising from disrupted PTEN nuclear localization on tumor promotion. This review will highlight the immediate need in understanding not only the cytoplasmic but also the nuclear functions of PTEN to gain more complete insights into how important PTEN is in preventing human cancers.
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Affiliation(s)
- Casey G. Langdon
- Department of Pediatrics, Darby Children’s Research Institute, Medical University of South Carolina, Charleston, SC 29425, USA; ; Tel.: +1-(843)-792-9289
- Hollings Cancer Center, Medical University of South Carolina, Charleston, SC 29425, USA
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3
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Targeting PTEN Regulation by Post Translational Modifications. Cancers (Basel) 2022; 14:cancers14225613. [PMID: 36428706 PMCID: PMC9688753 DOI: 10.3390/cancers14225613] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 11/07/2022] [Accepted: 11/11/2022] [Indexed: 11/17/2022] Open
Abstract
Phosphatidylinositol-3,4,5-triphosphate (PIP3) is a lipidic second messenger present at very low concentrations in resting normal cells. PIP3 levels, though, increase quickly and transiently after growth factor addition, upon activation of phosphatidylinositol 3-kinase (PI3-kinase). PIP3 is required for the activation of intracellular signaling pathways that induce cell proliferation, cell migration, and survival. Given the critical role of this second messenger for cellular responses, PIP3 levels must be tightly regulated. The lipid phosphatase PTEN (phosphatase and tensin-homolog in chromosome 10) is the phosphatase responsible for PIP3 dephosphorylation to PIP2. PTEN tumor suppressor is frequently inactivated in endometrium and prostate carcinomas, and also in glioblastoma, illustrating the contribution of elevated PIP3 levels for cancer development. PTEN biological activity can be modulated by heterozygous gene loss, gene mutation, and epigenetic or transcriptional alterations. In addition, PTEN can also be regulated by post-translational modifications. Acetylation, oxidation, phosphorylation, sumoylation, and ubiquitination can alter PTEN stability, cellular localization, or activity, highlighting the complexity of PTEN regulation. While current strategies to treat tumors exhibiting a deregulated PI3-kinase/PTEN axis have focused on PI3-kinase inhibition, a better understanding of PTEN post-translational modifications could provide new therapeutic strategies to restore PTEN action in PIP3-dependent tumors.
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4
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Nussinov R, Zhang M, Tsai CJ, Jang H. Phosphorylation and Driver Mutations in PI3Kα and PTEN Autoinhibition. Mol Cancer Res 2020; 19:543-548. [PMID: 33288731 DOI: 10.1158/1541-7786.mcr-20-0818] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 10/29/2020] [Accepted: 12/03/2020] [Indexed: 11/16/2022]
Abstract
PI3K and PTEN are the second and third most highly mutated proteins in cancer following only p53. Their actions oppose each other. PI3K phosphorylates signaling lipid PIP2 to PIP3 PTEN dephosphorylates it back. Driver mutations in both proteins accrue PIP3 PIP3 recruits AKT and PDK1 to the membrane, promoting cell-cycle progression. Here we review phosphorylation events and mutations in autoinhibition in PI3K and PTEN from the structural standpoint. Our purpose is to clarify how they control the autoinhibited states. In autoinhibition, a segment or a subunit of the protein occludes its functional site. Protein-protein interfaces are often only marginally stable, making them sensitive to changes in conditions in living cells. Phosphorylation can stabilize or destabilize the interfaces. Driver mutations commonly destabilize them. In analogy to "passenger mutations," we coin "passenger phosphorylation" to emphasize that the presence of a phosphorylation recognition sequence logo does not necessarily imply function. Rather, it may simply reflect a statistical occurrence. In both PI3K and PTEN, autoinhibiting phosphorylation events are observed in the occluding "piece." In PI3Kα, the "piece" is the p85α subunit. In PTEN, it is the C-terminal segment. In both enzymes the stabilized interface covers the domain that attaches to the membrane. Driver mutations that trigger rotation of the occluding piece or its deletion prompt activation. To date, both enzymes lack specific, potent drugs. We discuss the implications of detailed structural and mechanistic insight into oncogenic activation and how it can advance allosteric precision oncology.
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Affiliation(s)
- Ruth Nussinov
- Computational Structural Biology Section, Frederick National Laboratory for Cancer Research in the Laboratory of Cancer Immunometabolism, NCI, Frederick, Maryland. .,Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Mingzhen Zhang
- Computational Structural Biology Section, Frederick National Laboratory for Cancer Research in the Laboratory of Cancer Immunometabolism, NCI, Frederick, Maryland
| | - Chung-Jung Tsai
- Computational Structural Biology Section, Frederick National Laboratory for Cancer Research in the Laboratory of Cancer Immunometabolism, NCI, Frederick, Maryland
| | - Hyunbum Jang
- Computational Structural Biology Section, Frederick National Laboratory for Cancer Research in the Laboratory of Cancer Immunometabolism, NCI, Frederick, Maryland
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5
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Posttranslational Regulation and Conformational Plasticity of PTEN. Cold Spring Harb Perspect Med 2020; 10:cshperspect.a036095. [PMID: 31932468 DOI: 10.1101/cshperspect.a036095] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a tumor suppressor that is frequently down-modulated in human cancer. PTEN inhibits the phosphatidylinositol 3-phosphate kinase (PI3K)/AKT pathway through its lipid phosphatase activity. Multiple PI3K/AKT-independent actions of PTEN, protein-phosphatase activities and functions within the nucleus have also been described. PTEN, therefore, regulates many cellular processes including cell proliferation, survival, genomic integrity, polarity, migration, and invasion. Even a modest decrease in the functional dose of PTEN may promote cancer development. Understanding the molecular and cellular mechanisms that regulate PTEN protein levels and function, and how these may go awry in cancer contexts, is, therefore, key to fully understanding the role of PTEN in tumorigenesis. Here, we discuss current knowledge on posttranslational control and conformational plasticity of PTEN, as well as therapeutic possibilities toward reestablishment of PTEN tumor-suppressor activity in cancer.
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6
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Hasle N, Matreyek KA, Fowler DM. The Impact of Genetic Variants on PTEN Molecular Functions and Cellular Phenotypes. Cold Spring Harb Perspect Med 2019; 9:cshperspect.a036228. [PMID: 31451538 DOI: 10.1101/cshperspect.a036228] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Phosphatase and tensin homolog (PTEN) is a tumor suppressor that directly regulates a diverse array of cellular phenotypes, including growth, migration, morphology, and genome stability. How a single protein impacts so many important cellular processes remains a fascinating question. This question has been partially resolved by the characterization of a slew of missense variants that alter or eliminate PTEN's various molecular functions, including its enzymatic activity, subcellular localization, and posttranslational modifications. Here, we review what is known about how PTEN variants impact molecular function and, consequently, cellular phenotype. In particular, we highlight eight informative "sentinel variants" that abrogate distinct molecular functions of PTEN. We consider two published massively parallel assays of variant effect that measured the effect of thousands of PTEN variants on protein abundance and enzymatic activity. Finally, we discuss how characterization of clinically ascertained variants, establishment of clinical sequencing databases, and massively parallel assays of variant effect yield complementary datasets for dissecting PTEN's role in disease.
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Affiliation(s)
- Nicholas Hasle
- Department of Genome Sciences, University of Washington, Seattle, Washington 98195, USA
| | - Kenneth A Matreyek
- Department of Genome Sciences, University of Washington, Seattle, Washington 98195, USA
| | - Douglas M Fowler
- Department of Genome Sciences, University of Washington, Seattle, Washington 98195, USA.,Department of Bioengineering, University of Washington, Seattle, Washington 98195, USA.,Genetic Networks Program, CIFAR, Toronto, Ontario, M5G 1M1, Canada
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7
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Saito N, Hirai N, Aoki K, Suzuki R, Fujita S, Nakayama H, Hayashi M, Ito K, Sakurai T, Iwabuchi S. The Oncogene Addiction Switch from NOTCH to PI3K Requires Simultaneous Targeting of NOTCH and PI3K Pathway Inhibition in Glioblastoma. Cancers (Basel) 2019; 11:cancers11010121. [PMID: 30669546 PMCID: PMC6356490 DOI: 10.3390/cancers11010121] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Revised: 01/11/2019] [Accepted: 01/19/2019] [Indexed: 01/02/2023] Open
Abstract
The NOTCH pathway regulates neural stem cells and glioma initiating cells (GICs). However, blocking NOTCH activity with γ-secretase inhibitors (GSIs) fails to alter the growth of GICs, as GSIs seem to be active in only a fraction of GICs lines with constitutive NOTCH activity. Here we report loss of PTEN function as a critical event leading to resistance to NOTCH inhibition, which causes the transfer of oncogene addiction from the NOTCH pathway to the PI3K pathway. Drug cytotoxicity testing of eight GICs showed a differential growth response to GSI, and the GICs were thus stratified into two groups: sensitive and resistant. In the sensitive group, GICs with loss of PTEN function appeared less sensitive to GSI treatment. Here we show that NOTCH regulates PTEN expression and the activity of the PI3K pathway in GICs, as treatment with GSI attenuated the NOTCH pathway and increased PTEN expression. NOTCH regulates PTEN expression via Hes-1, as knockdown of Notch or Hes1 increased expression of PTEN. This novel observation suggests that both pathways must be simultaneously inhibited in order to improve therapeutic efficacy in human glioblastomas (GBMs).
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Affiliation(s)
- Norihiko Saito
- Department of Neurosurgery, Toho University Ohashi Medical Center, Tokyo 153-8515, Japan.
| | - Nozomi Hirai
- Department of Neurosurgery, Toho University Ohashi Medical Center, Tokyo 153-8515, Japan.
| | - Kazuya Aoki
- Department of Neurosurgery, Toho University Ohashi Medical Center, Tokyo 153-8515, Japan.
| | - Ryo Suzuki
- Department of Neurosurgery, Toho University Ohashi Medical Center, Tokyo 153-8515, Japan.
| | - Satoshi Fujita
- Department of Neurosurgery, Toho University Ohashi Medical Center, Tokyo 153-8515, Japan.
| | - Haruo Nakayama
- Department of Neurosurgery, Toho University Ohashi Medical Center, Tokyo 153-8515, Japan.
| | - Morito Hayashi
- Department of Neurosurgery, Toho University Ohashi Medical Center, Tokyo 153-8515, Japan.
| | - Keisuke Ito
- Department of Neurosurgery, Toho University Ohashi Medical Center, Tokyo 153-8515, Japan.
| | - Takatoshi Sakurai
- Department of Neurosurgery, Toho University Ohashi Medical Center, Tokyo 153-8515, Japan.
| | - Satoshi Iwabuchi
- Department of Neurosurgery, Toho University Ohashi Medical Center, Tokyo 153-8515, Japan.
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8
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Verrastro I, Tveen-Jensen K, Spickett CM, Pitt AR. The effect of HOCl-induced modifications on phosphatase and tensin homologue (PTEN) structure and function. Free Radic Res 2018; 52:232-247. [DOI: 10.1080/10715762.2018.1424333] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Ivan Verrastro
- School of Life and Health Sciences, Aston University, Birmingham, UK
| | | | | | - Andrew R. Pitt
- School of Life and Health Sciences, Aston University, Birmingham, UK
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9
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Lin M, Zhang X, Jia B, Guan S. Suppression of glioblastoma growth and angiogenesis through molecular targeting of methionine aminopeptidase-2. J Neurooncol 2017; 136:243-254. [PMID: 29116484 DOI: 10.1007/s11060-017-2663-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 10/30/2017] [Indexed: 12/16/2022]
Abstract
Methionine aminopeptidases (MetAPs) have been pharmacologically linked to cell growth, angiogenesis, and tumor progression, which make it an attractive target for cancer therapy. We investigated MetAP2's biological role in glioblastoma (GBM), an aggressive tumor characterized by massive neovascularization. We examined the effect of anti-MetAP2 RNA interference on proliferation and angiogenesis in GBM cell line. The biological effects of MetAP2 knockdown were assessed by comparing the proliferation, tumorigenecity, and angiogenesis of parental cells and MetAP2 knockdown cells. We generated MetAP2 knockdown cells using lentiviral short hairpin RNAs against MetAP2 in SNB19 GBM cells, which normally express high levels of MetAP2. MetAP2 knockdown cells were less proliferative and less tumorigenic when compared to the parental cells. MetAP2 knockdown decreased vascular endothelial growth factor (VEGF) secretion and expression at the mRNA and protein levels. Decreased VEGF expression in MetAP2 knockdown cells correlated very well with decreased vessel formation in a tube formation assay. We showed that VEGF suppression in MetAP2 knockdown cells was mediated by the von Hippel-Lindau protein. In in vivo animal studies using an intracranial SNB19 tumor model, MetAP2 knockdown also reduced the tumor growth rate and angiogenesis, which in turn prolonged the survival of mice in xenograft model. Our results show that MetAP2 regulates angiogenesis in GBM and identify MetAP2-specific substrates that may serve as candidates for clinical assay development.
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Affiliation(s)
- Ming Lin
- Department of Anesthesiology, Guangdong Provincial Hospital of Chinese Medicine, Guangzhou, 510120, People's Republic of China
| | - Xuyu Zhang
- Department of Anesthesiology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, 510089, People's Republic of China
| | - Bingjie Jia
- School of Biology and Biological Engineering, South China University of Technology, 382 Wai Huan Dong Road, Guangzhou, 510006, People's Republic of China
| | - Su Guan
- School of Biology and Biological Engineering, South China University of Technology, 382 Wai Huan Dong Road, Guangzhou, 510006, People's Republic of China.
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10
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Kim DH, Suh J, Surh YJ, Na HK. Regulation of the tumor suppressor PTEN by natural anticancer compounds. Ann N Y Acad Sci 2017; 1401:136-149. [PMID: 28891094 DOI: 10.1111/nyas.13422] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 05/31/2017] [Accepted: 06/05/2017] [Indexed: 12/20/2022]
Abstract
The tumor suppressor phosphatase and tensin homologue (PTEN) has phosphatase activity, with phosphatidylinositol (3,4,5)-trisphosphate (PIP3), a product of phosphatidylinositol 3-kinase (PI3K), as one of the principal substrates. PTEN is a negative regulator of the Akt pathway, which plays a fundamental role in controlling cell growth, survival, and proliferation. Loss of PTEN function has been observed in many different types of cancer. Functional inactivation of PTEN as a consequence of germ-line mutations or promoter hypermethylation predisposes individuals to malignancies. PTEN undergoes posttranslational modifications, such as oxidation, acetylation, phosphorylation, SUMOylation, and ubiquitination, which influence its catalytic activity, interactions with other proteins, and subcellular localization. Cellular redox status is crucial for posttranslational modification of PTEN and its functional consequences. Oxidative stress and inflammation are major causes of loss of PTEN function. Pharmacologic or nutritional restoration of PTEN function is considered a reliable strategy in the management of PTEN-defective cancer. In this review, we highlight natural compounds, such as curcumin, indol-3 carbinol, and omega-3 fatty acids, that have the potential to restore or potentiate PTEN expression/activity, thereby suppressing cancer cell proliferation, survival, and resistance to chemotherapeutic agents.
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Affiliation(s)
- Do-Hee Kim
- Tumor Microenvironment Global Core Research Center, College of Pharmacy, Seoul National University, Seoul, South Korea
| | - Jinyoung Suh
- Tumor Microenvironment Global Core Research Center, College of Pharmacy, Seoul National University, Seoul, South Korea
| | - Young-Joon Surh
- Tumor Microenvironment Global Core Research Center, College of Pharmacy, Seoul National University, Seoul, South Korea.,Department of Molecular Medicine and Biopharmaceutical Sciences, Graduate School of Convergence Science, Seoul National University, Seoul, South Korea.,Cancer Research Institute, Seoul National University, Seoul, South Korea
| | - Hye-Kyung Na
- Department of Food Science and Biotechnology, College of Knowledge-Based Services Engineering, Sungshin Women's University, Seoul, South Korea
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11
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The functions of tumor suppressor PTEN in innate and adaptive immunity. Cell Mol Immunol 2017; 14:581-589. [PMID: 28603282 DOI: 10.1038/cmi.2017.30] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2017] [Revised: 04/10/2017] [Accepted: 04/10/2017] [Indexed: 12/20/2022] Open
Abstract
The tumor suppressor phosphatase and tensin homolog (PTEN) is a lipid and protein phosphatase that is able to antagonize the PI3K/AKT pathway and inhibit tumor growth. PTEN also possesses phosphatase-independent functions. Genetic alterations of PTEN may lead to the deregulation of cell proliferation, survival, differentiation, energy metabolism and cellular architecture and mobility. Although the role of PTEN in tumor suppression is extensively documented and well established, the evidence for its roles in immunity did not start to accumulate until recently. In this review, we will focus on the newly discovered functions of PTEN in the regulation of innate and adaptive immunity, including antiviral responses.
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12
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APOBEC3G acts as a therapeutic target in mesenchymal gliomas by sensitizing cells to radiation-induced cell death. Oncotarget 2017; 8:54285-54296. [PMID: 28903341 PMCID: PMC5589580 DOI: 10.18632/oncotarget.17348] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 04/11/2017] [Indexed: 12/31/2022] Open
Abstract
Genomic, transcriptional, and proteomic analyses of brain tumors reveal that subtypes differ in their pathway activity, progression, and response to therapy. We performed an expression profiling of Glioma Initiating Cells (GICs) and comparative analysis between different groups of GICs indicates major variations in gene expression. Hierarchical clustering analysis revealed groups of GICs reflecting their heterogeneity, and among some of the genes as major regulators of mesenchymal phenotype, we identified ABOBEC3G as one of the most discriminating genes in mesenchymal group. ABOBEC3G revealed a strong correlation with overall survival in TCGA GBM patient cohorts. APOBEC3G regulates cell invasion and silencing of this gene in GICs inhibits cell invasion and also glioma sphere initiation. APOBEC3G controls invasion through TGFβ/Smad2 pathway by regulating Smad2 target genes Thrombospondin 1, matrix metallopeptidase 2 and TIMP metallopeptidase inhibitor 1. We also show that targeting APOBEC3G can sensitize cancer cells to radiation induced cell death by attenuating activation of the DNA repair pathway. This response is mainly shown by decreased pChk2 expression in knockdown APOBEC3G cells. Taken together, we show that APOBEC3G gene is a mesenchymal enriched gene that controls invasion and knockdown of APOBEC3G sensitizes cells to radiation induced cell death, suggesting that APOBEC3G can be considered for use in stratifying patients with GBM for prognostic considerations.
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13
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Kanda M, Kodera Y. Molecular mechanisms of peritoneal dissemination in gastric cancer. World J Gastroenterol 2016; 22:6829-6840. [PMID: 27570420 PMCID: PMC4974582 DOI: 10.3748/wjg.v22.i30.6829] [Citation(s) in RCA: 117] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2016] [Revised: 05/31/2016] [Accepted: 06/15/2016] [Indexed: 02/06/2023] Open
Abstract
Peritoneal dissemination represents a devastating form of gastric cancer (GC) progression with a dismal prognosis. There is no effective therapy for this condition. The 5-year survival rate of patients with peritoneal dissemination is 2%, even including patients with only microscopic free cancer cells without macroscopic peritoneal nodules. The mechanism of peritoneal dissemination of GC involves several steps: detachment of cancer cells from the primary tumor, survival in the free abdominal cavity, attachment to the distant peritoneum, invasion into the subperitoneal space and proliferation with angiogenesis. These steps are not mutually exclusive, and combinations of different molecular mechanisms can occur in each process of peritoneal dissemination. A comprehensive understanding of the molecular events involved in peritoneal dissemination is important and should be systematically pursued. It is crucial to identify novel strategies for the prevention of this condition and for identification of markers of prognosis and the development of molecular-targeted therapies. In this review, we provide an overview of recently published articles addressing the molecular mechanisms of peritoneal dissemination of GC to provide an update on what is currently known in this field and to propose novel promising candidates for use in diagnosis and as therapeutic targets.
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14
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Tzenaki N, Aivaliotis M, Papakonstanti EA. Focal adhesion kinase phosphorylates the phosphatase and tensin homolog deleted on chromosome 10 under the control of p110δ phosphoinositide-3 kinase. FASEB J 2015; 29:4840-52. [PMID: 26251180 DOI: 10.1096/fj.15-274589] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2015] [Accepted: 07/27/2015] [Indexed: 12/21/2022]
Abstract
The phosphatase and tensin homolog deleted on chromosome 10 (PTEN) tumor suppressor protein is regulated by various mechanisms that are not fully understood. This includes regulation by Tyr phosphorylation by a mechanism that remains elusive. Here, we show that focal adhesion kinase (FAK) phosphorylates PTEN in vitro, in cell-free systems and in cells. Furthermore, by mass spectrometry, we identified Tyr336 on PTEN as being phosphorylated by FAK. Tyr336 phosphorylation increased phosphatase activity, protein-lipid interaction, and protein stability of PTEN. In cells, including primary mouse macrophages and human cancer cell lines, FAK was found to be negatively regulated by p110δ phosphoinositide-3 kinase (PI3K), whereas the activation of FAK was positively regulated by RhoA-associated kinase (ROCK). Indeed, the phosphorylation of FAK was unexpectedly increased in macrophages derived from mice expressing kinase-dead p110δ. Pharmacologic inactivation of RhoA/ROCK reduced the phosphorylation of FAK to normal levels in cells with genetically inactivated p110δ. Likewise, pharmacologic inactivation of FAK reduced the phosphorylation of PTEN in cells expressing kinase-dead p110δ and restored the functional defects of p110δ inactivation, including Akt phosphorylation and cell proliferation. This work identifies FAK as a target of p110δ PI3K that links RhoA with PTEN and establishes for the first time that PTEN is a substrate of FAK-mediated Tyr phosphorylation.
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Affiliation(s)
- Niki Tzenaki
- *Department of Biochemistry, School of Medicine, University of Crete, Vassilika Vouton, Heraklion, Greece; and Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Crete, Greece
| | - Michalis Aivaliotis
- *Department of Biochemistry, School of Medicine, University of Crete, Vassilika Vouton, Heraklion, Greece; and Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Crete, Greece
| | - Evangelia A Papakonstanti
- *Department of Biochemistry, School of Medicine, University of Crete, Vassilika Vouton, Heraklion, Greece; and Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Crete, Greece
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15
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Fragoso R, Barata JT. Kinases, tails and more: regulation of PTEN function by phosphorylation. Methods 2015; 77-78:75-81. [PMID: 25448482 DOI: 10.1016/j.ymeth.2014.10.015] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Revised: 10/10/2014] [Accepted: 10/15/2014] [Indexed: 12/15/2022] Open
Abstract
Phosphorylation regulates the conformation, stability, homo- and heterotypic protein interactions, localization, and activity of the tumor suppressor PTEN. From a simple picture, at the beginning of this millennium, recognizing that CK2 phosphorylated PTEN at the C-terminus and thereby impacted on PTEN stability and activity, research has led to a significantly more complex scenario today, where for instance GSK3, Plk3, ATM, ROCK or Src-family kinases are also gaining the spotlight in this evolving play. Here, we review the current knowledge on the kinases that phosphorylate PTEN, and on the impact that specific phosphorylation events have on PTEN function.
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Affiliation(s)
- Rita Fragoso
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, 1649-028 Lisboa, Portugal
| | - João T Barata
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, 1649-028 Lisboa, Portugal.
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16
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Effect of Notch expression in glioma stem cells on therapeutic response to chemo-radiotherapy in recurrent glioblastoma. Brain Tumor Pathol 2015; 32:176-83. [PMID: 25665548 DOI: 10.1007/s10014-015-0215-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Accepted: 01/27/2015] [Indexed: 12/28/2022]
Abstract
Glioma stem cells (GSCs) have the capacity to repopulate tumors and mediate resistance to radiotherapy and chemotherapy. The Notch signaling pathway is important in proliferation, stem cell maintenance, cell differentiation, and tumorigenesis in GSCs. In this study, we compared CD133, Notch, and VEGF expressions in histological sections of primary and recurrent glioblastomas after radiotherapy and chemotherapy. In vitro study, the γ-secretase inhibitor inhibited NICD, Hes1 and pVEGFR2 expressions in GSCs. GSCs cultured under endothelial conditions undergo endothelial differentiation. Tumor samples were collected from 27 patients at the time of tumor recurrence. We used immunohistochemical techniques to compare expression of CD133, Notch-1 and VEGF. Expressions of CD133-, Notch-1-, and VEGF-positive glioma cells were higher in recurrent glioblastoma after radiotherapy and chemotherapy. To determine the clinical importance of Notch-1 expression in glioblastoma, we analyzed 15 patients who had received bevacizumab therapy followed by a second surgery at recurrence. OS was significantly longer in cases with Notch-1 negativity (8.8 months) than in those with I Notch-1 positivity (6.8 months). We noted that GSCs have the potential for endothelial differentiation with Notch activity. We believe that Notch-1 is a potential target and/or biomarker for antiangiogenic treatments.
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17
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Saito N, Fu J, Zheng S, Yao J, Wang S, Liu DD, Yuan Y, Sulman EP, Lang FF, Colman H, Verhaak RG, Yung WKA, Koul D. A high Notch pathway activation predicts response to γ secretase inhibitors in proneural subtype of glioma tumor-initiating cells. Stem Cells 2014; 32:301-12. [PMID: 24038660 DOI: 10.1002/stem.1528] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Accepted: 07/27/2013] [Indexed: 11/07/2022]
Abstract
Genomic, transcriptional, and proteomic analyses of brain tumors reveal subtypes that differ in pathway activity, progression, and response to therapy. However, a number of small molecule inhibitors under development vary in strength of subset and pathway-specificity, with molecularly targeted experimental agents tending toward stronger specificity. The Notch signaling pathway is an evolutionarily conserved pathway that plays an important role in multiple cellular and developmental processes. We investigated the effects of Notch pathway inhibition in glioma tumor-initiating cell (GIC, hereafter GIC) populations using γ secretase inhibitors. Drug cytotoxicity testing of 16 GICs showed differential growth responses to the inhibitors, stratifying GICs into responders and nonresponders. Responder GICs had an enriched proneural gene signature in comparison to nonresponders. Also gene set enrichment analysis revealed 17 genes set representing active Notch signaling components NOTCH1, NOTCH3, HES1, MAML1, DLL-3, JAG2, and so on, enriched in responder group. Analysis of The Cancer Genome Atlas expression dataset identified a group (43.9%) of tumors with proneural signature showing high Notch pathway activation suggesting γ secretase inhibitors might be of potential value to treat that particular group of proneural glioblastoma (GBM). Inhibition of Notch pathway by γ secretase inhibitor treatment attenuated proliferation and self-renewal of responder GICs and induces both neuronal and astrocytic differentiation. In vivo evaluation demonstrated prolongation of median survival in an intracranial mouse model. Our results suggest that proneural GBM characterized by high Notch pathway activation may exhibit greater sensitivity to γ secretase inhibitor treatment, holding a promise to improve the efficiency of current glioma therapy.
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Affiliation(s)
- Norihiko Saito
- Department of Neuro-Oncology, Brain Tumor Center, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
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18
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Lima-Fernandes E, Misticone S, Boularan C, Paradis JS, Enslen H, Roux PP, Bouvier M, Baillie GS, Marullo S, Scott MGH. A biosensor to monitor dynamic regulation and function of tumour suppressor PTEN in living cells. Nat Commun 2014; 5:4431. [PMID: 25028204 DOI: 10.1038/ncomms5431] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Accepted: 06/17/2014] [Indexed: 01/01/2023] Open
Abstract
Tumour suppressor PTEN is a phosphatase that negatively regulates the PI3K/AKT pathway. The ability to directly monitor PTEN conformation and function in a rapid, sensitive manner is a key step towards developing anti-cancer drugs aimed at enhancing or restoring PTEN-dependent pathways. Here we developed an intramolecular bioluminescence resonance energy transfer (BRET)-based biosensor, capable of detecting signal-dependent PTEN conformational changes in live cells. The biosensor retains intrinsic properties of PTEN, enabling structure-function and kinetic analyses. BRET shifts, indicating conformational change, were detected following mutations that disrupt intramolecular PTEN interactions, promoting plasma membrane targeting and also following physiological PTEN activation. Using the biosensor as a reporter, we uncovered PTEN activation by several G protein-coupled receptors, previously unknown as PTEN regulators. Trastuzumab, used to treat ERBB2-overexpressing breast cancers also elicited activation-associated PTEN conformational rearrangement. We propose the biosensor can be used to identify pathways regulating PTEN or molecules that enhance its anti-tumour activity.
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Affiliation(s)
- Evelyne Lima-Fernandes
- 1] Department of Endocrinology, Metabolism and Diabetes, Inserm, U1016, Institut Cochin, 27 rue du Faubourg St Jaques, Paris 75014, France [2] CNRS, UMR8104, Paris 75014, France [3] University Paris Descartes, Sorbonne Paris Cité, Paris 75014, France [4]
| | - Stanislas Misticone
- 1] Department of Endocrinology, Metabolism and Diabetes, Inserm, U1016, Institut Cochin, 27 rue du Faubourg St Jaques, Paris 75014, France [2] CNRS, UMR8104, Paris 75014, France [3] University Paris Descartes, Sorbonne Paris Cité, Paris 75014, France [4]
| | - Cédric Boularan
- 1] Department of Endocrinology, Metabolism and Diabetes, Inserm, U1016, Institut Cochin, 27 rue du Faubourg St Jaques, Paris 75014, France [2] CNRS, UMR8104, Paris 75014, France [3] University Paris Descartes, Sorbonne Paris Cité, Paris 75014, France [4]
| | - Justine S Paradis
- 1] Molecular Biology Program, Department of Biochemistry, Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, Quebec, Canada H3C 3J7 [2] Department of Pathology and Cell Biology, Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, Quebec, Canada H3C 3J7 [3]
| | - Hervé Enslen
- 1] Department of Endocrinology, Metabolism and Diabetes, Inserm, U1016, Institut Cochin, 27 rue du Faubourg St Jaques, Paris 75014, France [2] CNRS, UMR8104, Paris 75014, France [3] University Paris Descartes, Sorbonne Paris Cité, Paris 75014, France
| | - Philippe P Roux
- 1] Molecular Biology Program, Department of Biochemistry, Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, Quebec, Canada H3C 3J7 [2] Department of Pathology and Cell Biology, Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, Quebec, Canada H3C 3J7
| | - Michel Bouvier
- 1] Molecular Biology Program, Department of Biochemistry, Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, Quebec, Canada H3C 3J7 [2] Department of Pathology and Cell Biology, Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, Quebec, Canada H3C 3J7
| | - George S Baillie
- Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Stefano Marullo
- 1] Department of Endocrinology, Metabolism and Diabetes, Inserm, U1016, Institut Cochin, 27 rue du Faubourg St Jaques, Paris 75014, France [2] CNRS, UMR8104, Paris 75014, France [3] University Paris Descartes, Sorbonne Paris Cité, Paris 75014, France
| | - Mark G H Scott
- 1] Department of Endocrinology, Metabolism and Diabetes, Inserm, U1016, Institut Cochin, 27 rue du Faubourg St Jaques, Paris 75014, France [2] CNRS, UMR8104, Paris 75014, France [3] University Paris Descartes, Sorbonne Paris Cité, Paris 75014, France
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19
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Identification of nucleolus-localized PTEN and its function in regulating ribosome biogenesis. Mol Biol Rep 2014; 41:6383-90. [DOI: 10.1007/s11033-014-3518-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Accepted: 06/19/2014] [Indexed: 10/25/2022]
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20
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Zhang LL, Liu J, Lei S, Zhang J, Zhou W, Yu HG. PTEN inhibits the invasion and metastasis of gastric cancer via downregulation of FAK expression. Cell Signal 2014; 26:1011-1020. [PMID: 24486402 DOI: 10.1016/j.cellsig.2014.01.025] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Revised: 01/24/2014] [Accepted: 01/24/2014] [Indexed: 12/22/2022]
Abstract
The tumor suppressor gene phosphatase and tensin homolog (PTEN) is essential in inhibiting tumor growth and metastasis. However, the mechanism by which PTEN restricts gastric cancer progression and metastasis remains largely elusive. Here we demonstrated that PTEN overexpression or knockdown in gastric cancer cells led to the downregulation or upregulation of focal adhesion kinase (FAK), and decreased or increased cell invasion, respectively. Moreover, FAK overexpression could rescue the inhibition of cell invasion by PTEN. These results were further confirmed in orthotropic gastric cancer nude mice model. In addition, in human gastric cancer tissues, PTEN protein level was conversely correlated with FAK protein level. Mechanistically, we found that PTEN inhibited PI3K/NF-κB pathway and inhibited the DNA binding of NF-κB on FAK promoter. Taken together, our data reveal a novel mechanism that PTEN inhibits the growth and invasion of gastric cancer via the downregulation of FAK expression and suggest that exploiting PTEN/PI3K/NF-κB/FAK axis is a promising approach to treat gastric cancer metastasis.
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Affiliation(s)
- Ling-Li Zhang
- Department of Gastroenterology, Renmin Hospital of Wuhan University, Wuhan 430060, Hubei Province, People's Republic of China; Institute for Gastroenterology and Hepatology, Renmin Hospital of Wuhan University, Wuhan 430060, Hubei Province, People's Republic of China
| | - Jie Liu
- Department of Gastroenterology, Renmin Hospital of Wuhan University, Wuhan 430060, Hubei Province, People's Republic of China; Institute for Gastroenterology and Hepatology, Renmin Hospital of Wuhan University, Wuhan 430060, Hubei Province, People's Republic of China
| | - Shen Lei
- Department of Gastroenterology, Renmin Hospital of Wuhan University, Wuhan 430060, Hubei Province, People's Republic of China; Institute for Gastroenterology and Hepatology, Renmin Hospital of Wuhan University, Wuhan 430060, Hubei Province, People's Republic of China
| | - Jun Zhang
- Department of Gastroenterology, Renmin Hospital of Wuhan University, Wuhan 430060, Hubei Province, People's Republic of China; Institute for Gastroenterology and Hepatology, Renmin Hospital of Wuhan University, Wuhan 430060, Hubei Province, People's Republic of China
| | - Wei Zhou
- Department of Gastroenterology, Renmin Hospital of Wuhan University, Wuhan 430060, Hubei Province, People's Republic of China; Institute for Gastroenterology and Hepatology, Renmin Hospital of Wuhan University, Wuhan 430060, Hubei Province, People's Republic of China
| | - Hong-Gang Yu
- Department of Gastroenterology, Renmin Hospital of Wuhan University, Wuhan 430060, Hubei Province, People's Republic of China; Institute for Gastroenterology and Hepatology, Renmin Hospital of Wuhan University, Wuhan 430060, Hubei Province, People's Republic of China.
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21
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Hopkins BD, Hodakoski C, Barrows D, Mense SM, Parsons RE. PTEN function: the long and the short of it. Trends Biochem Sci 2014; 39:183-90. [PMID: 24656806 DOI: 10.1016/j.tibs.2014.02.006] [Citation(s) in RCA: 230] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 02/11/2014] [Accepted: 02/13/2014] [Indexed: 12/31/2022]
Abstract
Phosphatase and tensin homolog deleted on chromosome ten (PTEN) is a phosphatase that is frequently altered in cancer. PTEN has phosphatase-dependent and -independent roles, and genetic alterations in PTEN lead to deregulation of protein synthesis, the cell cycle, migration, growth, DNA repair, and survival signaling. PTEN localization, stability, conformation, and phosphatase activity are controlled by an array of protein-protein interactions and post-translational modifications. Thus, PTEN-interacting and -modifying proteins have profound effects on the tumor suppressive functions of PTEN. Moreover, recent studies identified mechanisms by which PTEN can exit cells, via either exosomal export or secretion, and act on neighboring cells. This review focuses on modes of PTEN protein regulation and ways in which perturbations in this regulation may lead to disease.
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Affiliation(s)
- Benjamin D Hopkins
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, 1470 Madison Avenue, New York, NY 10029, USA
| | - Cindy Hodakoski
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, 1470 Madison Avenue, New York, NY 10029, USA
| | - Douglas Barrows
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, 1470 Madison Avenue, New York, NY 10029, USA
| | - Sarah M Mense
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, 1470 Madison Avenue, New York, NY 10029, USA
| | - Ramon E Parsons
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, 1470 Madison Avenue, New York, NY 10029, USA.
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22
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Ali A, Saluja SS, Hajela K, Mishra PK, Rizvi MA. Mutational and expressional analyses of PTEN
gene in colorectal cancer from Northern India. Mol Carcinog 2013; 53 Suppl 1:E45-52. [DOI: 10.1002/mc.22001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2012] [Revised: 11/24/2012] [Accepted: 12/17/2012] [Indexed: 12/12/2022]
Affiliation(s)
- Asgar Ali
- Genome Biology Laboratory; Department of Biosciences; Jamia Millia Islamia New Delhi India
| | - Sundeep S. Saluja
- Department of Gastrointestinal Surgery; G. B. Pant Hospital; New Delhi India
| | - Krishnan Hajela
- School of Life Sciences; Devi Ahilya Vishwavidyalaya; Indore India
| | - Pramod K. Mishra
- Department of Gastrointestinal Surgery; G. B. Pant Hospital; New Delhi India
| | - Moshahid A. Rizvi
- Genome Biology Laboratory; Department of Biosciences; Jamia Millia Islamia New Delhi India
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23
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Moon SH, Kim DK, Cha Y, Jeon I, Song J, Park KS. PI3K/Akt and Stat3 signaling regulated by PTEN control of the cancer stem cell population, proliferation and senescence in a glioblastoma cell line. Int J Oncol 2013; 42:921-8. [PMID: 23314408 DOI: 10.3892/ijo.2013.1765] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Accepted: 07/04/2012] [Indexed: 11/06/2022] Open
Abstract
Malignant gliomas are the most common primary brain tumor in adults. A number of genes have been implicated in glioblastoma including mutation and deletion of PTEN. PTEN is a regulator of PI3K-mediated Akt signaling pathways and has been recognized as a therapeutic target in glioblastoma. To achieve potent therapeutic inhibition of the PI3K-Akt pathway in glioblastoma, it is essential to understand the interplay between the regulators of its activation. Here, ectopic expression of PTEN in the U-87MG human glioblastoma-astrocytoma cell line is shown to result in the depletion of glioblastoma stem cells (GSCs) and to cause growth retardation and senescence. These effects are likely to be associated with PTEN-mediated cooperative perturbation of Akt and Stat3 signals. Using an in vivo rat model of glioblastoma, we showed that PTEN-overexpressing U-87MG cells failed to induce tumor formation, while untreated U-87MG cells did so. Furthermore, cells expressing the phosphorylated form of Stat3 were completely absent from the brain of rats implanted with PTEN-overexpressing U-87MG cells. Based on these results, PTEN appears to function as a crucial inhibitor of GSCs and as an inducer of senescence, suggesting that functional enhancement of the PTEN pathway will be useful to provide a therapeutic strategy for targeting glioblastoma.
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Affiliation(s)
- Seok-Ho Moon
- Department of Biomedical Science, College of Life Science, CHA University, Seoul, Republic of Korea
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24
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A New Insight into Structural and Functional Impact of Single-Nucleotide Polymorphisms in PTEN Gene. Cell Biochem Biophys 2012; 66:249-63. [DOI: 10.1007/s12013-012-9472-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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25
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Resistance to EGF receptor inhibitors in glioblastoma mediated by phosphorylation of the PTEN tumor suppressor at tyrosine 240. Proc Natl Acad Sci U S A 2012; 109:14164-9. [PMID: 22891331 DOI: 10.1073/pnas.1211962109] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Glioblastoma multiforme (GBM) is the most aggressive of the astrocytic malignancies and the most common intracranial tumor in adults. Although the epidermal growth factor receptor (EGFR) is overexpressed and/or mutated in at least 50% of GBM cases and is required for tumor maintenance in animal models, EGFR inhibitors have thus far failed to deliver significant responses in GBM patients. One inherent resistance mechanism in GBM is the coactivation of multiple receptor tyrosine kinases, which generates redundancy in activation of phosphoinositide-3'-kinase (PI3K) signaling. Here we demonstrate that the phosphatase and tensin homolog deleted on chromosome 10 (PTEN) tumor suppressor is frequently phosphorylated at a conserved tyrosine residue, Y240, in GBM clinical samples. Phosphorylation of Y240 is associated with shortened overall survival and resistance to EGFR inhibitor therapy in GBM patients and plays an active role in mediating resistance to EGFR inhibition in vitro. Y240 phosphorylation can be mediated by both fibroblast growth factor receptors and SRC family kinases (SFKs) but does not affect the ability of PTEN to antagonize PI3K signaling. These findings show that, in addition to genetic loss and mutation of PTEN, its modulation by tyrosine phosphorylation has important implications for the development and treatment of GBM.
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26
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Nongenomic Mechanisms of PTEN Regulation. Int J Cell Biol 2012; 2012:379685. [PMID: 22536248 PMCID: PMC3320059 DOI: 10.1155/2012/379685] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Revised: 01/16/2012] [Accepted: 01/17/2012] [Indexed: 11/21/2022] Open
Abstract
A large amount of data supports the view that PTEN is a bona fide tumor suppressor gene. However, recent evidence suggests that derailment of cellular localization and expression levels of functional nonmutated PTEN is a determining force in inducing abnormal cellular and tissue outcomes. As the cellular mechanisms that regulate normal PTEN enzymatic activity resolve, it is evident that deregulation of these mechanisms can alter cellular processes and tissue architecture and ultimately lead to oncogenic transformation. Here we discuss PTEN ubiquitination, PTEN complex formation with components of the adherens junction, PTEN nuclear localization, and microRNA regulation of PTEN as essential regulatory mechanisms that determine PTEN function independent of gene mutations and epigenetic events.
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27
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Tzenaki N, Andreou M, Stratigi K, Vergetaki A, Makrigiannakis A, Vanhaesebroeck B, Papakonstanti EA. High levels of p110δ PI3K expression in solid tumor cells suppress PTEN activity, generating cellular sensitivity to p110δ inhibitors through PTEN activation. FASEB J 2012; 26:2498-508. [PMID: 22391131 DOI: 10.1096/fj.11-198192] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Class IA PI3K isoforms have divergent, nonredundant cell biological roles. In untransformed cells and tissues, p110α and p110β are ubiquitously expressed, whereas p110δ expression is highly enriched in leukocytes. High levels of p110δ expression have been documented in some solid tumor cell lines, but the functional role is unknown. This study aimed to elucidate the link between elevated expression of p110δ PI3K and cancer. We report that in breast and prostate cancer cells that contain leukocyte levels of p110δ, p110δ activity dampens the activity of the PTEN tumor suppressor. Indeed, inactivation of p110δ in these cells led to PTEN activation, suppression of Akt phosphorylation, and inhibition of cell proliferation, with inhibition of PTEN activity being able to counterbalance p110δ inactivation. Likewise, forced overexpression of p110δ in cells with low p110δ expression reduced PTEN activity, resulting in increased Akt phosphorylation. Our data indicate that the oncogenic potential of p110δ PI3K overexpression might at least partially act through PTEN inactivation, and that p110δ-selective PI3K inhibitors can have a dual antitumor mechanism, namely by directly inhibiting p110δ signaling and by a broader inhibition of class I PI3K activity through PTEN activation. These data may have important implications in the intervention of breast cancer.
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Affiliation(s)
- Niki Tzenaki
- Department of Biochemistry, School of Medicine, University of Crete, Vassilika Vouton, GR-71110 Heraklion, Greece
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28
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Penas C, Ramachandran V, Ayad NG. The APC/C Ubiquitin Ligase: From Cell Biology to Tumorigenesis. Front Oncol 2012; 1:60. [PMID: 22655255 PMCID: PMC3356048 DOI: 10.3389/fonc.2011.00060] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Accepted: 12/22/2011] [Indexed: 01/15/2023] Open
Abstract
The ubiquitin proteasome system (UPS) is required for normal cell proliferation, vertebrate development, and cancer cell transformation. The UPS consists of multiple proteins that work in concert to target a protein for degradation via the 26S proteasome. Chains of an 8.5-kDa protein called ubiquitin are attached to substrates, thus allowing recognition by the 26S proteasome. Enzymes called ubiquitin ligases or E3s mediate specific attachment to substrates. Although there are over 600 different ubiquitin ligases, the Skp1-Cullin-F-box (SCF) complexes and the anaphase promoting complex/cyclosome (APC/C) are the most studied. SCF involvement in cancer has been known for some time while APC/C's cancer role has recently emerged. In this review we will discuss the importance of APC/C to normal cell proliferation and development, underscoring its possible contribution to transformation. We will also examine the hypothesis that modulating a specific interaction of the APC/C may be therapeutically attractive in specific cancer subtypes. Finally, given that the APC/C pathway is relatively new as a cancer target, therapeutic interventions affecting APC/C activity may be beneficial in cancers that are resistant to classical chemotherapy.
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Affiliation(s)
- Clara Penas
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine Miami, FL, USA
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29
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Hasegawa Y, Suzuki H, Altay O, Chen H, Zhang JH. Treatment with sodium orthovanadate reduces blood-brain barrier disruption via phosphatase and tensin homolog deleted on chromosome 10 (PTEN) phosphorylation in experimental subarachnoid hemorrhage. J Neurosci Res 2011; 90:691-7. [PMID: 22183833 DOI: 10.1002/jnr.22801] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Revised: 08/24/2011] [Accepted: 08/30/2011] [Indexed: 12/15/2022]
Abstract
Attenuation of blood-brain barrier (BBB) disruption is one of the therapeutic candidates for treatment of subarachnoid hemorrhage (SAH). In this study, the protective effect of sodium orthovanadate (SOV) on BBB disruption was investigated in SAH using the endovascular perforation model. Fifty-five rats were randomly assigned to sham-operated, SAH treated with saline (as a vehicle), or 10 mg/kg SOV groups and were evaluated for neurofunction and Evans blue dye extravasation. The phosphorylation of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) and mitogen-activated protein kinase (MAPK) and the expression of matrix metalloproteinase-9 (MMP-9), occludin, and collagen-IV were examined by Western blot analyses. Cell death among endothelial cells was revealed by immunofluorescence and terminal deoxynucleotidyl transferase-mediated uridine 5'-triphosphate-biotin nick end-labeling staining. SOV significantly improved neurofunction and reduced Evans blue dye extravasation in brains after SAH. SOV phosphorylated PTEN, decreased phospho-JNK and MMP-9, and preserved occludin expression. SOV also attenuated SAH-induced capillary endothelial cell death. The current study showed that SOV was protective against BBB disruption after SAH, possibly via PTEN phosphorylation.
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Affiliation(s)
- Yu Hasegawa
- Department of Physiology, Loma Linda University School of Medicine, Loma Linda, CA 92354, USA
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30
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Koul D, Fu J, Shen R, LaFortune TA, Wang S, Tiao N, Kim YW, Liu JL, Ramnarian D, Yuan Y, Garcia-Echevrria C, Maira SM, Yung WKA. Antitumor activity of NVP-BKM120--a selective pan class I PI3 kinase inhibitor showed differential forms of cell death based on p53 status of glioma cells. Clin Cancer Res 2011; 18:184-95. [PMID: 22065080 DOI: 10.1158/1078-0432.ccr-11-1558] [Citation(s) in RCA: 134] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
PURPOSE The aim of this study was to show preclinical efficacy and clinical development potential of NVP-BKM120, a selective pan class I phosphatidylinositol-3 kinase (PI3K) inhibitor in human glioblastoma (GBM) cells in vitro and in vivo. EXPERIMENTAL DESIGN The effect of NVP-BKM120 on cellular growth was assessed by CellTiter-Blue assay. Flow cytometric analyses were carried out to measure the cell-cycle, apoptosis, and mitotic index. Mitotic catastrophe was detected by immunofluorescence. The efficacy of NVP-BKM120 was tested using intracranial U87 glioma model. RESULTS We tested the biologic effects of a selective PI3K inhibitor NVP-BKM120 in a set of glioma cell lines. NVP-BKM120 treatment for 72 hours resulted in a dose-dependent growth inhibition and effectively blocked the PI3K/Akt signaling cascade. Although we found no obvious relationship between the cell line's sensitivity to NVP-BKM120 and the phosphatase and tensin homolog (PTEN) and epidermal growth factor receptor (EGFR) statuses, we did observe a differential sensitivity pattern with respect to p53 status, with glioma cells containing wild-type p53 more sensitive than cells with mutated or deleted p53. NVP-BKM120 showed differential forms of cell death on the basis of p53 status of the cells with p53 wild-type cells undergoing apoptotic cell death and p53 mutant/deleted cells having a mitotic catastrophe cell death. NVP-BKM120 mediates mitotic catastrophe mainly through Aurora B kinase. Knockdown of p53 in p53 wild-type U87 glioma cells displayed microtubule misalignment, multiple centrosomes, and mitotic catastrophe cell death. Parallel to the assessment of the compound in in vitro settings, in vivo efficacy studies using an intracranial U87 tumor model showed an increased median survival from 26 days (control cohort) to 38 and 48 days (treated cohorts). CONCLUSION Our present findings establish that NVP-BKM120 inhibits the PI3K signaling pathways, leading to different forms of cell death on the basis of p53 statuses. Further studies are warranted to determine if NVP-BKM120 has potential as a glioma treatment.
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Affiliation(s)
- Dimpy Koul
- Department of Neuro-Oncology, Brain Tumor Center, The University of Texas M D Anderson Cancer Center, Houston, Texas 77030, USA
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31
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Guan S, Shen R, Lafortune T, Tiao N, Houghton P, Yung WKA, Koul D. Establishment and characterization of clinically relevant models of ependymoma: a true challenge for targeted therapy. Neuro Oncol 2011; 13:748-58. [PMID: 21653596 DOI: 10.1093/neuonc/nor037] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The development of new therapies for ependymoma is dramatically limited by the absence of optimal in vivo and in vitro models. Successful ependymoma treatment requires a profound understanding of the disease's biological characteristics. This study focuses on the establishment and characterization of in vivo and in vitro models of ependymoma to study the molecular pathways necessary for growth and progression in ependymoma. In addition, this study also emphasizes the use of these models for therapeutic intervention of ependymomas. We established optimal conditions for the long-term growth of 2 tumor xenografts and cultures of 2 human ependymoma cell lines. This study also describes the establishment of in vivo models. Histopathologic features of tumors from both intracranial and subcutaneous sites in mice revealed perivascular pseudorosettes and ependymal rosettes, which are typical morphologic features of ependymoma similar to those observed in human specimens. The in vitro models revealed glial fibrillary acidic protein and vimentin expression, and ultrastructural studies demonstrated numerous microvilli, caveolae, and microfilaments commonly seen in human ependymoma. To study signaling pathway alterations in ependymoma, we profiled established ependymoma models with Western blot analysis that demonstrated aberrant activation mainly of the phosphoinositide 3-kinase and epidermal growth factor receptor signaling pathways. Targeting phosphoinositide 3-kinase and epidermal growth factor receptor signaling pathways with small molecule inhibitors showed growth inhibitory effects. These models can also be used to study the standard therapies used for ependymomas, as shown by some of the drugs used in this study. Therefore, the models developed will assist in the biological studies and preclinical drug screening for ependymomas.
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Affiliation(s)
- Su Guan
- Brain Tumor Center, Department of Neuro-Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
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Burgos-Ramos E, Chowen JA, Arilla-Ferreiro E, Canelles S, Argente J, Barrios V. Chronic central leptin infusion modifies the response to acute central insulin injection by reducing the interaction of the insulin receptor with IRS2 and increasing its association with SOCS3. J Neurochem 2011; 117:175-85. [PMID: 21255014 DOI: 10.1111/j.1471-4159.2011.07191.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Leptin and insulin have overlapping intracellular signaling mechanisms and exert anorexigenic actions in the hypothalamus. We aimed to determine how chronic exposure to increased leptin affects the hypothalamic response to a rise in insulin. We analyzed the activation and interactions of components of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway in the hypothalamus of rats treated icv for 14 days with leptin followed by a central injection of insulin and killed 15 min later. Insulin increased glycemia and chronic leptin reduced this insulin induced rise in glucose. Leptin decreased the association between the insulin receptor beta chain (IRβ) and insulin receptor substrate 2 (IRS2), augmented the association between Janus kinase 2 and IRS2, increased levels of the catalytic subunit of PI3K and pAkt-Ser473 and decreased forkhead box O number 1 levels. Insulin reduced the association between suppressor of the cytokine signaling 3 and IRβ, increased IRβ-IRS2 association and pAkt-Thr308 levels, with chronic leptin exposure blunting these effects. In conclusion, chronic exposure to leptin decreases the central response to insulin by increasing suppressor of the cytokine signaling 3 association to IR, which inhibits insulin signaling at the level of interaction of its receptor with IRS2 and activates PI3K by promoting Janus kinase 2-IRS2 association. Thus, these results suggest that this mechanism could be a target for the treatment of insulin resistance.
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Affiliation(s)
- Emma Burgos-Ramos
- Department of Endocrinology, Hospital Infantil Universitario Niño Jesús, Instituto Investigación Sanitaria Princesa, Madrid, Spain
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Song MS, Carracedo A, Salmena L, Song SJ, Egia A, Malumbres M, Pandolfi PP. Nuclear PTEN regulates the APC-CDH1 tumor-suppressive complex in a phosphatase-independent manner. Cell 2011; 144:187-99. [PMID: 21241890 PMCID: PMC3249980 DOI: 10.1016/j.cell.2010.12.020] [Citation(s) in RCA: 315] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2010] [Revised: 09/20/2010] [Accepted: 12/15/2010] [Indexed: 10/18/2022]
Abstract
PTEN is a frequently mutated tumor suppressor gene that opposes the PI3K/AKT pathway through dephosphorylation of phosphoinositide-3,4,5-triphosphate. Recently, nuclear compartmentalization of PTEN was found as a key component of its tumor-suppressive activity; however its nuclear function remains poorly defined. Here we show that nuclear PTEN interacts with APC/C, promotes APC/C association with CDH1, and thereby enhances the tumor-suppressive activity of the APC-CDH1 complex. We find that nuclear exclusion but not phosphatase inactivation of PTEN impairs APC-CDH1. This nuclear function of PTEN provides a straightforward mechanistic explanation for the fail-safe cellular senescence response elicited by acute PTEN loss and the tumor-suppressive activity of catalytically inactive PTEN. Importantly, we demonstrate that PTEN mutant and PTEN null states are not synonymous as they are differentially sensitive to pharmacological inhibition of APC-CDH1 targets such as PLK1 and Aurora kinases. This finding identifies a strategy for cancer patient stratification and, thus, optimization of targeted therapies. PAPERCLIP:
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Affiliation(s)
- Min Sup Song
- Cancer Genetics Program, Beth Israel Deaconess Cancer Center, Department of Medicine and Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston MA 02215, USA
| | - Arkaitz Carracedo
- Cancer Genetics Program, Beth Israel Deaconess Cancer Center, Department of Medicine and Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston MA 02215, USA
| | - Leonardo Salmena
- Cancer Genetics Program, Beth Israel Deaconess Cancer Center, Department of Medicine and Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston MA 02215, USA
| | - Su Jung Song
- Cancer Genetics Program, Beth Israel Deaconess Cancer Center, Department of Medicine and Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston MA 02215, USA
| | - Ainara Egia
- Cancer Genetics Program, Beth Israel Deaconess Cancer Center, Department of Medicine and Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston MA 02215, USA
| | - Marcos Malumbres
- Cell Division and Cancer Group, Molecular Oncology Programme, Centro Nacional de Investigaciones Oncológicas (CNIO), 28029 Madrid, Spain
| | - Pier Paolo Pandolfi
- Cancer Genetics Program, Beth Israel Deaconess Cancer Center, Department of Medicine and Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston MA 02215, USA
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Koul D, Shen R, Kim YW, Kondo Y, Lu Y, Bankson J, Ronen SM, Kirkpatrick DL, Powis G, Yung WKA. Cellular and in vivo activity of a novel PI3K inhibitor, PX-866, against human glioblastoma. Neuro Oncol 2010; 12:559-69. [PMID: 20156803 PMCID: PMC2940638 DOI: 10.1093/neuonc/nop058] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2009] [Accepted: 09/28/2009] [Indexed: 01/28/2023] Open
Abstract
The phosphatidylinositol-3-kinase (PI3K)/Akt oncogenic pathway is critical in glioblastomas. Loss of PTEN, a negative regulator of the PI3K pathway or activated PI3K/Akt pathway that drive increased proliferation, survival, neovascularization, glycolysis, and invasion is found in 70%-80% of malignant gliomas. Thus, PI3K is an attractive therapeutic target for malignant glioma. We report that a new irreversible PI3K inhibitor, PX-866, shows potent inhibitory effects on the PI3K/Akt signaling pathway in glioblastoma. PX-866 did not induce any apoptosis in glioma cells; however, an increase in autophagy was observed. PX-866 inhibited the invasive and angiogenic capabilities of cultured glioblastoma cells. In vivo, PX-866 inhibited subcutaneous tumor growth and increased the median survival time of animals with intracranial tumors. We also assessed the potential of proton magnetic resonance spectroscopy (MRS) as a noninvasive method to monitor response to PX-866. Our findings show that PX-866 treatment causes a drop in the MRS-detectable choline-to-NAA, ratio and identify this partial normalization of the tumor metabolic profile as a biomarker of molecular drug action. Our studies affirm that the PI3K pathway is a highly specific molecular target for therapies for glioblastoma and other cancers with aberrant PI3K/PTEN expression.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - W. K. Alfred Yung
- Brain Tumor Center, Department of Neuro-Oncology (D.K., R.S., Y.-W.K., Y.K., W.K.A.Y.), Department of Systems Biology (Y.L.), Department of Imaging Physics (J.B.), Department of Experimental Diagnostic Imaging (S.M.R), and Department of Experimental Therapeutics (G.P.), The University of Texas M. D. Anderson Cancer Center, Houston, Texas; Oncothyreon Inc., Seattle, Washington (D.L.K.)
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Abstract
Peroxiredoxins (Prdxs) are a family of small (22-27 kDa) nonseleno peroxidases currently known to possess six mammalian isoforms. Although their individual roles in cellular redox regulation and antioxidant protection are quite distinct, they all catalyze peroxide reduction of H(2)O(2), organic hydroperoxides and peroxynitrite. They are found to be expressed ubiquitously and in high levels, suggesting that they are both an ancient and important enzyme family. Prdxs can be divided into three major subclasses: typical 2-cysteine (2-Cys) Prdxs (Prdx1-4), atypical 2-Cys Prdx (Prdx 5) and 1-Cys Prdx (Prdx 6). Recent evidence suggests that 2-Cys peroxiredoxins are more than "just simple peroxidases". This hypothesis has been discussed elegantly in recent review articles, considering "over"-oxidation of the protonated thiolate peroxidatic cysteine and post-translational modification of Prdxs as processes initiating a mechanistic switch from peroxidase to chaperon function. The process of over-oxidation of the peroxidatic cysteine (C(P)) occurs during catalysis in the presence of thioredoxin (Trx), thus rendering the sulfenic moiety to sulfinic acid, which can be reduced by sulfiredoxin (Srx). However, further oxidation to sulfonic acid is believed to promote Prdx degradation or, as recently shown, the formation of oligomeric peroxidase-inactive chaperones with questionable H(2)O(2)-scavenging capacity. In the light of this and given that Prdx1 has recently been shown by us and by others to interact directly with signaling molecules, we will explore the possibility that H(2)O(2) regulates signaling in the cell in a temporal and spatial fashion via oxidizing Prdx1. Therefore, this review will focus on H(2)O(2) modulating cell signaling via Prdxs by discussing: (1) the activity of Prdxs towards H(2)O(2); (2) sub cellular localization and availability of other peroxidases, such as catalase or glutathione peroxidases; (3) the availability of Prdxs reducing systems, such as thioredoxin and sulfiredoxin and lastly, (4) Prdx1 interacting signaling molecules.
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Affiliation(s)
- Carola A Neumann
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, Charleston, SC, USA.
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Cao J, Schulte J, Knight A, Leslie NR, Zagozdzon A, Bronson R, Manevich Y, Beeson C, Neumann CA. Prdx1 inhibits tumorigenesis via regulating PTEN/AKT activity. EMBO J 2009; 28:1505-17. [PMID: 19369943 PMCID: PMC2688529 DOI: 10.1038/emboj.2009.101] [Citation(s) in RCA: 282] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2008] [Accepted: 03/20/2009] [Indexed: 01/12/2023] Open
Abstract
It is widely accepted that reactive oxygen species (ROS) promote tumorigenesis. However, the exact mechanisms are still unclear. As mice lacking the peroxidase peroxiredoxin1 (Prdx1) produce more cellular ROS and die prematurely of cancer, they offer an ideal model system to study ROS-induced tumorigenesis. Prdx1 ablation increased the susceptibility to Ras-induced breast cancer. We, therefore, investigated the role of Prdx1 in regulating oncogenic Ras effector pathways. We found Akt hyperactive in fibroblasts and mammary epithelial cells lacking Prdx1. Investigating the nature of such elevated Akt activation established a novel role for Prdx1 as a safeguard for the lipid phosphatase activity of PTEN, which is essential for its tumour suppressive function. We found binding of the peroxidase Prdx1 to PTEN essential for protecting PTEN from oxidation-induced inactivation. Along those lines, Prdx1 tumour suppression of Ras- or ErbB-2-induced transformation was mediated mainly via PTEN.
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Affiliation(s)
- Juxiang Cao
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics Medical Medical University of South Carolina, Charleston, SC, USA
| | - Jennifer Schulte
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics Medical Medical University of South Carolina, Charleston, SC, USA
| | | | - Nicholas R Leslie
- Division of Molecular Physiology, College of Life Sciences, University of Dundee, Wellcome Trust Biocentre, Dundee, UK
| | - Agnieszka Zagozdzon
- Department of Pathology, Dana Farber Cancer Institute, Harvard Medical School, Boston, MA, USA
| | - Roderick Bronson
- Department of Pathology, Harvard Medical School, Boston, MA, USA
| | - Yefim Manevich
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics Medical Medical University of South Carolina, Charleston, SC, USA
| | - Craig Beeson
- Department of Pharmaceutical and Biomedical Sciences, Medical University of South Carolina, Charleston, SC, USA
| | - Carola A Neumann
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics Medical Medical University of South Carolina, Charleston, SC, USA
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Abstract
PI3-kinase and PTEN are major positive and negative regulators, respectively, of the PI3-kinase pathway, which regulates growth, survival, and proliferation. These key signaling components are two of the most frequently mutated proteins in human cancers, resulting in unregulated activation of PI3K signaling and providing irrefutable genetic evidence of the central role of this pathway in tumorigenesis. PTEN regulates PI3K signaling by dephosphorylating the lipid signaling intermediate PIP(3), but PTEN may have additional phosphatase-independent activities, as well as other functions in the nucleus. In this review, we highlight current work showing cancer-relevant complexities in the regulation of PTEN and PI3K activity, potential novel functions for PTEN, and feedback regulation within the pathway. The significance and complexity of PI3K signaling make it an important but challenging therapeutic target for cancer.
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Affiliation(s)
- Nader Chalhoub
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN 38105-2794, USA.
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Leslie NR, Batty IH, Maccario H, Davidson L, Downes CP. Understanding PTEN regulation: PIP2, polarity and protein stability. Oncogene 2008; 27:5464-76. [PMID: 18794881 DOI: 10.1038/onc.2008.243] [Citation(s) in RCA: 187] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The PTEN tumour suppressor is a lipid and protein phosphatase that inhibits phosphoinositide 3-kinase (PI3K)-dependent signalling by dephosphorylating phosphatidylinositol 3,4,5-trisphosphate (PtdInsP(3)). Here, we discuss the concept of PTEN as an 'interfacial enzyme', which exists in a high activity state when bound transiently at membrane surfaces containing its substrate and other acidic lipids, such as PtdIns(4,5)P(2) and phosphatidylserine (PtdSer). This mechanism ensures that PTEN functions in a spatially restricted manner, and may explain its involvement in forming the gradients of PtdInsP(3), which are necessary for generating and/or sustaining cell polarity during motility, in developing neurons and in epithelial tissues. Coordinating PTEN activity with alternative mechanisms of PtdInsP(3) metabolism, by the tightly regulated SHIP 5-phoshatases, synthesizing the independent second messenger PtdIns(3,4)P(2), may also be important for cellular polarization in some cell types. Superimposed on this interfacial mechanism are additional post-translational regulatory processes, which generally act to reduce PTEN activity. Oxidation of the active site cysteine residue by reactive oxygen species and phosphorylation of serine/threonine residues at sites in the C-terminus of the protein inhibit PTEN. These phosphorylation sites also appear to play a role in regulating both stability and localization of PTEN, as does ubiquitination of PTEN. Because genetic studies in mice show that the level of expression of PTEN in an organism profoundly influences tumour susceptibility, factors that regulate PTEN, localization, activity and turnover should be important in understanding its biological functions as a tumour suppressor.
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Affiliation(s)
- N R Leslie
- Division of Molecular Physiology, College of Life Sciences, University of Dundee, James Black Centre, Dundee, Scotland, UK.
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Abstract
The tumor suppressor phosphatase and tensin homolog (PTEN) functions as a phosphoinositide 3-phosphatase, that antagonizes phosphatidylinositol 3-kinase action, and negatively regulates cell proliferation and survival signals. Inactivation of PTEN by loss-of-function mutations gives rise to deregulated hyperproliferation of cells, leading to oncogenic transformation. Recent studies have identified a number of upstream regulatory factors for PTEN and unveiled that the impairment in the PTEN regulatory system potentially becomes a causal factor for oncogenic transformation of cells. This article will review the PTEN inactivation mechanism which is linked to human tumorigenesis, particularly focusing on recent research progress in PTEN regulators.
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Affiliation(s)
- Tomohiko Maehama
- Department of Biochemistry and Cell Biology, National Institute of Infectious Diseases, Shinjuku-ku, Tokyo 162-8640, Japan.
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Papakonstanti EA, Ridley AJ, Vanhaesebroeck B. The p110delta isoform of PI 3-kinase negatively controls RhoA and PTEN. EMBO J 2007; 26:3050-61. [PMID: 17581634 PMCID: PMC1914109 DOI: 10.1038/sj.emboj.7601763] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2007] [Accepted: 05/23/2007] [Indexed: 01/22/2023] Open
Abstract
Inactivation of PI 3-kinase (PI3K) signalling is critical for tumour suppression by PTEN. This is thought to be a unidirectional relationship in which PTEN degrades the lipids produced by PI3K, thus controlling cell proliferation, survival and migration. We now show that this relationship is in fact bidirectional, whereby PI3K reciprocally controls PTEN. We report that the p110delta PI3K negatively regulates PTEN, through a pathway involving inhibition of RhoA. Inactivation of p110delta in macrophages led to reduced Akt and Rac1 activation, but paradoxically to increased RhoA and PTEN activity. Partial inactivation of p190RhoGAP and a reduced binding of cytoplasmic RhoA to the cyclin-dependent kinase inhibitor p27 both contributed to the increased RhoA-GTP levels upon p110delta inactivation. Pharmacological inhibition of ROCK, a downstream effector kinase of RhoA, restored all signalling and functional defects of p110delta inactivation, including Akt phosphorylation, chemotaxis and proliferation. This work identifies the RhoA/ROCK pathway as a major target of p110delta-mediated PI3K signalling, and establishes for the first time that PI3K controls itself, via a feedback loop involving PTEN.
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Affiliation(s)
| | - Anne J Ridley
- Ludwig Institute for Cancer Research, London, UK
- Department of Biochemistry and Molecular Biology, University College London, London, UK
| | - Bart Vanhaesebroeck
- Ludwig Institute for Cancer Research, London, UK
- Department of Biochemistry and Molecular Biology, University College London, London, UK
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41
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Gajewski JE, Bird MJ, Crowhurst MO, Sio-Seng Lio D, Liu J, Wettenhall REH, Zhu HJ, Cheng HC. Expression, generation, and purification of unphosphorylated and phospho-Ser-380/Thr-382/Thr-383 form of recombinant PTEN phosphatase. Protein Expr Purif 2007; 55:334-42. [PMID: 17562371 DOI: 10.1016/j.pep.2007.04.024] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2007] [Revised: 04/27/2007] [Accepted: 04/27/2007] [Indexed: 11/19/2022]
Abstract
The dual specificity phosphatase PTEN exerts its tumour suppressor and cell-migration regulatory functions by dephosphorylating the phospholipid substrate, phosphatidylinositol-3,4,5-trisphosphate (PI(3,4,5)P(3)), and phosphotyrosine protein substrates. PTEN functions are regulated by phospholipid binding, interactions with other cellular proteins and phosphorylation at multiple sites. Precisely, how the phosphorylation and binding events modulate PTEN activity and structure remains mostly unclear. Detailed studies of this issue require the availability of significant quantity of both the unphosphorylated and phosphorylated forms of purified recombinant PTEN. Here, we describe the successful expression and purification of recombinant rat PTEN using a baculovirus-infected Spodoptera frugiperda (Sf9) cell expression system. The recombinant PTEN was purified to near homogeneity using four sequential column chromatographic steps. The specific enzymatic activity of the purified preparation in dephosphorylating PI(3,4,5,)P(3) and the artificial phosphotyrosine substrate poly(Glu/Tyr) are 6.7 nmol/min/microg and 0.006 pmol/min/microg, respectively. Intriguingly, similar to PTEN expressed in mammalian cells, the recombinant PTEN was phosphorylated in the infected insect cells at Ser-380, Thr-382, and Thr-383 at the C-terminal tail. Treatment with alkaline phosphatase fully dephosphorylated these sites. After the treatment, the unphosphorylated PTEN and alkaline phosphatase could be separated by ion exchange column chromatography. The availability of the phosphorylated and unphosphorylated forms of recombinant PTEN permits future investigations into the three-dimensional structures of the phosphorylated and unphosphorylated forms of PTEN, and the role of phosphorylation in regulating PTEN activity, phospholipid- and protein-binding affinities.
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Affiliation(s)
- Joanna E Gajewski
- Department of Biochemistry & Molecular Biology, The University of Melbourne, Parkville, Vic. 3010, Australia
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Koul D, Shen R, Shishodia S, Takada Y, Bhat KP, Reddy SAG, Aggarwal BB, Yung WKA. PTEN down regulates AP-1 and targets c-fos in human glioma cells via PI3-kinase/Akt pathway. Mol Cell Biochem 2007; 300:77-87. [PMID: 17235455 DOI: 10.1007/s11010-006-9371-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2006] [Accepted: 10/26/2006] [Indexed: 01/05/2023]
Abstract
The continual activation of signaling cascades results in dramatic consequences that include loss of cellular growth control and neoplastic transformation. We show here that phosphoinositide 3-kinase and its mediator Akt was constitutively activated in glioma and that this might be due to the aberrant expression of their natural antagonist PTEN. The PTEN (phosphatase and tensin homologue deleted on chromosome ten) tumor suppressor gene modulates cell growth and survival through mechanisms that are incompletely understood. In this study, we investigated the possibility that PTEN mediates its effects through modulation of transcription factor AP-1, which is in part due to decrease in c-fos expression which was dependent on PI3kinase activity. Consistent with a reduction in the c-fos levels, an AP-1 dependent reporter gene was poorly induced in the PTEN expressing cell lines. In contrast to its effect on c-fos, PTEN did not affect the expression of c-Jun and other fos family members. We also show that the effect of PTEN on c-fos expression was due to its ability to antagonize PI3-kinase and could be mimicked by the expression of dominant negative Akt mutant. Taken together, these data indicate that the aberrant expression of PTEN contributes to the activation of the PI3kinase/Akt pathway and its transcription factor mediators in glioma. We conclude that the ectopic expression of PTEN down regulates the proliferation of glioma cells through the suppression of AP-1 and that this target might be essential for its central role in the growth and survival of glioma cancer cells.
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Affiliation(s)
- Dimpy Koul
- Department of Neuro-Oncology, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA.
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Zhang QG, Wu DN, Han D, Zhang GY. Critical role of PTEN in the coupling between PI3K/Akt and JNK1/2 signaling in ischemic brain injury. FEBS Lett 2007; 581:495-505. [PMID: 17239858 DOI: 10.1016/j.febslet.2006.12.055] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2006] [Accepted: 12/28/2006] [Indexed: 10/23/2022]
Abstract
JNK pathway is an important pro-apoptotic kinase cascade mediating cell death in response to a variety of extracellular stimuli including excitotoxicity, which results in selective and delayed neuronal death in the hippocampal CA1. On the contrary, activation of the protein kinase Akt, which is controlled by the opposing actions of PI3K and PTEN, contributes to enhanced resistance to apoptosis through multiple mechanisms. We here demonstrate that the temporal pattern of Akt activation reversely correlates with JNK1/2 activation following various time points of ischemic reperfusion. However, the activation of JNK1/2 could be decreased by the elevation of Akt activation via increasing the tyrosine phosphorylation of PTEN by bpv(pic), a potent PTPases inhibitor for PTEN, or by intracerebroventricular infusion of PTEN antisense oligodeoxynucleotides (AS-ODNs). In contrast, JNK1/2 activation was significantly increased by preventing PTEN degradation after pretreatment with proteasome inhibitor. The neuroprotective effects of bpv(pic) and PTEN AS-ODNs were significant in the CA1 subfield after transient global ischemia. In conclusion, the present results clearly show that PTEN plays a key regulatory role in the cross-talk between cell survival PI3K/Akt pathway and pro-death JNK pathway, and raise a new possibility that agents targeting phosphatase PTEN may offer a great promise to expand the therapeutic options in protecting neurons form ischemic brain damage.
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Affiliation(s)
- Quan-Guang Zhang
- Research Center for Biochemistry and Molecular Biology, Xuzhou Medical College, 84 West Huai-hai Road, Xuzhou 221002, China
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Downes CP, Ross S, Maccario H, Perera N, Davidson L, Leslie NR. Stimulation of PI 3-kinase signaling via inhibition of the tumor suppressor phosphatase, PTEN. ACTA ACUST UNITED AC 2006; 47:184-94. [PMID: 17343901 DOI: 10.1016/j.advenzreg.2006.12.018] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- C Peter Downes
- Division of Molecular Physiology, Faculty of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK.
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45
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Koul D, Takada Y, Shen R, Aggarwal BB, Yung WKA. PTEN enhances TNF-induced apoptosis through modulation of nuclear factor-kappaB signaling pathway in human glioma cells. Biochem Biophys Res Commun 2006; 350:463-71. [PMID: 17011514 PMCID: PMC2703012 DOI: 10.1016/j.bbrc.2006.09.077] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2006] [Accepted: 09/15/2006] [Indexed: 11/20/2022]
Abstract
The PTEN tumor suppressor gene modulates cell growth and survival known to be regulated by the activation of the transcription factor NFkappaB, suggesting PTEN might affect the NFkappaB activation pathway. We found that PTEN inhibited NFkappaB activation induced by TNF. The suppression of NFkappaB activation correlated with sequential inhibition of the tumor necrosis factor-induced expression of NFkappaB-regulated anti-apoptotic (IAP1, IAP2, Bcl-2, Bcl-xL, cFLIP, Bfl-1/A1, and survivin) gene products. Downregulation of the antiapoptotic genes by PTEN increased TNF-induced apoptosis, as indicated by caspase activation, TUNEL, annexin staining, and esterase assay. We conclude that the ectopic expression of PTEN enhances TNF-induced apoptosis and downregulates the proliferation of glioma cells through the suppression of various molecules including NFkappaB, and various mediators of cellular survival and proliferation, and that this targets might be essential for its central role in the growth and survival of glioma cancer cells.
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Affiliation(s)
- Dimpy Koul
- Brain Tumor Center, Department of Neuro-Oncology, The University of Texas M.D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA.
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Abstract
Phosphatase and tensin homologue deleted on chromosome 10 (PTEN) is a phosphatidylinositol phosphate phosphatase and is frequently inactivated in human cancers. The balance between phosphoinositide 3-kinase (PI3K) and PTEN determines PI(3,4,5)P3 levels. PI3K is regulated by a variety of intracellular and extracellular signals, but little is known about the regulation of PTEN. In this article, we review control of PTEN function by phosphorylation as well as by binding of lipid and protein partners.
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Affiliation(s)
- Arne Gericke
- Chemistry Department, Kent State University, Kent, OH 44242, USA
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Yang Y, Shao N, Luo G, Li L, Nilsson-Ehle P, Xu N. Relationship between PTEN gene expression and differentiation of human glioma. Scand J Clin Lab Invest 2006; 66:469-475. [PMID: 17000554 DOI: 10.1080/00365510600763285] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
OBJECTIVE To investigate the relationship between PTEN gene expression and differentiation of glioma. MATERIAL AND METHODS The quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR) method was applied to detect PTEN mRNA levels in glioma tissues. Tumor-adjacent normal tissues and benign brain tumors were used as controls. Relative PTEN mRNA levels were determined as the ratio of PTEN and GAPDH, which were correlated with the clinical-pathological results. RESULTS PTEN mRNA levels were significantly lower in the glioma tissues than in the benign brain tumors and tumor-adjacent normal tissues, whereas there were no statistical differences between benign brain tumor and the tumor-adjacent normal tissues. According to the pathological examinations, PTEN mRNA levels were higher in the high differential glioma than the low differential glioma. CONCLUSIONS PTEN gene expression was suppressed in the glioma, which is related to the clinical-pathological results. It is suggested that determination of PTEN mRNA levels by RT-PCR could be a novel marker of disease classification.
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Affiliation(s)
- Y Yang
- Department of Neurosurgery, Third Affiliated Hospital of Suzhou University, Changzhou, China
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Liu JL, Sheng X, Hortobagyi ZK, Mao Z, Gallick GE, Yung WKA. Nuclear PTEN-mediated growth suppression is independent of Akt down-regulation. Mol Cell Biol 2005; 25:6211-24. [PMID: 15988030 PMCID: PMC1168816 DOI: 10.1128/mcb.25.14.6211-6224.2005] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The tumor suppressor gene PTEN is a phosphoinositide phosphatase that is inactivated by deletion and/or mutation in diverse human tumors. Wild-type PTEN is expressed both in the cytoplasm and nucleus in normal cells, with a preferential nuclear localization in differentiated or resting cells. To elucidate the relationship between PTEN's subcellular localization and its biologic activities, we constructed different PTEN mutants that targeted PTEN protein into different subcellular compartments. Our data show that the subcellular localization patterns of a PTEN (deltaPDZB) mutant versus a G129R phosphatase mutant were indistinguishable from those of wild-type PTEN. In contrast, the Myr-PTEN mutant demonstrated an enhanced association with the cell membrane. We found that nuclear PTEN alone is capable of suppressing anchorage-independent growth and facilitating G1 arrest in U251MG cells without inhibiting Akt activity. Nuclear compartment-specific PTEN-induced growth suppression is dependent on possessing a functional lipid phosphatase domain. In addition, the down-regulation of p70S6K could be mediated, at least in part, through activation of AMP-activated protein kinase in an Akt-independent fashion. Introduction of a constitutively active mutant of Akt, Akt-DD, only partially rescues nuclear PTEN-mediated growth suppression. Our collective results provide the first direct evidence that PTEN can contribute to G1 growth arrest through an Akt-independent signaling pathway.
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Affiliation(s)
- Juinn-Lin Liu
- Brain Tumor Center, Department of Neuro-Oncology, UT M. D. Anderson Cancer Center, 1515 Holcombe Blvd., Box 431, Houston, Texas 77030, USA.
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Sanchez T, Thangada S, Wu MT, Kontos CD, Wu D, Wu H, Hla T. PTEN as an effector in the signaling of antimigratory G protein-coupled receptor. Proc Natl Acad Sci U S A 2005; 102:4312-7. [PMID: 15764699 PMCID: PMC555509 DOI: 10.1073/pnas.0409784102] [Citation(s) in RCA: 132] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
PTEN, a tumor suppressor phosphatase, is important in the regulation of cell migration and invasion. Physiological regulation of PTEN (phosphatase and tensin homolog deleted on chromosome 10) by cell surface receptors has not been described. Here, we show that the bioactive lipid sphingosine 1-phosphate (S1P), which acts through the S1P2 receptor (S1P2R) G protein-coupled receptor (GPCR) to inhibit cell migration, utilizes PTEN as a signaling intermediate. S1P2R inhibition of cell migration is abrogated by dominant-negative PTEN expression. S1P was unable to efficiently inhibit the migration of Pten(DeltaloxP/DeltaloxP) mouse embryonic fibroblasts; however, the antimigratory effect was restored upon the expression of PTEN. S1P2R activation of Rho GTPase is not affected in Pten(DeltaloxP/DeltaloxP) cells, and dominant-negative Rho GTPase reversed S1P inhibition of cell migration in WT cells but not in Pten(DeltaloxP/DeltaloxP) cells, suggesting that PTEN acts downstream of the Rho GTPase. Ligand activation of the S1P2R receptor stimulated the coimmunoprecipitation of S1P2R and PTEN. Interestingly, S1P2R signaling increased PTEN phosphatase activity in membrane fractions. Furthermore, tyrosine phosphorylation of PTEN was stimulated by S1P2R signaling. These data suggest that the S1P2R receptor actively regulates the PTEN phosphatase by a Rho GTPase-dependent pathway to inhibit cell migration. GPCR regulation of PTEN maybe a general mechanism in signaling events of cell migration and invasion.
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Affiliation(s)
- Teresa Sanchez
- Center for Vascular Biology, Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06030, USA
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Leslie N, Downes C. PTEN function: how normal cells control it and tumour cells lose it. Biochem J 2005; 382:1-11. [PMID: 15193142 PMCID: PMC1133909 DOI: 10.1042/bj20040825] [Citation(s) in RCA: 330] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2004] [Revised: 06/10/2004] [Accepted: 06/11/2004] [Indexed: 01/26/2023]
Abstract
The PTEN (phosphatase and tensin homologue deleted on chromosome 10) tumour suppressor is a PI (phosphoinositide) 3-phosphatase that can inhibit cellular proliferation, survival and growth by inactivating PI 3-kinase-dependent signalling. It also suppresses cellular motility through mechanisms that may be partially independent of phosphatase activity. PTEN is one of the most commonly lost tumour suppressors in human cancer, and its deregulation is also implicated in several other diseases. Here we discuss recent developments in our understanding of how the cellular activity of PTEN is regulated, and the closely related question of how this activity is lost in tumours. Cellular PTEN function appears to be regulated by controlling both the expression of the enzyme and also its activity through mechanisms including oxidation and phosphorylation-based control of non-substrate membrane binding. Therefore mutation of PTEN in tumours disrupts not only the catalytic function of PTEN, but also its regulatory aspects. However, although mutation of PTEN is uncommon in many human tumour types, loss of PTEN expression seems to be more frequent. It is currently unclear how these tumours lose PTEN expression in the absence of mutation, and while some data implicate other potential tumour suppressors and oncogenes in this process, this area seems likely to be a key focus of future research.
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Affiliation(s)
- Nick R. Leslie
- Division of Cell Signalling, School of Life Sciences, University of Dundee, Dundee DD1 5EH, U.K
- email
| | - C. Peter Downes
- Division of Cell Signalling, School of Life Sciences, University of Dundee, Dundee DD1 5EH, U.K
- email
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