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Archer M, Dogra N, Dovey Z, Ganta T, Jang HS, Khusid JA, Lantz A, Mihalopoulos M, Stockert JA, Zahalka A, Björnebo L, Gaglani S, Noh MR, Kaplan SA, Mehrazin R, Badani KK, Wiklund P, Tsao K, Lundon DJ, Mohamed N, Lucien F, Padanilam B, Gupta M, Tewari AK, Kyprianou N. Role of α- and β-adrenergic signaling in phenotypic targeting: significance in benign and malignant urologic disease. Cell Commun Signal 2021; 19:78. [PMID: 34284799 PMCID: PMC8290582 DOI: 10.1186/s12964-021-00755-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 05/28/2021] [Indexed: 01/17/2023] Open
Abstract
The urinary tract is highly innervated by autonomic nerves which are essential in urinary tract development, the production of growth factors, and the control of homeostasis. These neural signals may become dysregulated in several genitourinary (GU) disease states, both benign and malignant. Accordingly, the autonomic nervous system is a therapeutic target for several genitourinary pathologies including cancer, voiding dysfunction, and obstructing nephrolithiasis. Adrenergic receptors (adrenoceptors) are G-Protein coupled-receptors that are distributed throughout the body. The major function of α1-adrenoceptors is signaling smooth muscle contractions through GPCR and intracellular calcium influx. Pharmacologic intervention of α-and β-adrenoceptors is routinely and successfully implemented in the treatment of benign urologic illnesses, through the use of α-adrenoceptor antagonists. Furthermore, cell-based evidence recently established the antitumor effect of α1-adrenoceptor antagonists in prostate, bladder and renal tumors by reducing neovascularity and impairing growth within the tumor microenvironment via regulation of the phenotypic epithelial-mesenchymal transition (EMT). There has been a significant focus on repurposing the routinely used, Food and Drug Administration-approved α1-adrenoceptor antagonists to inhibit GU tumor growth and angiogenesis in patients with advanced prostate, bladder, and renal cancer. In this review we discuss the current evidence on (a) the signaling events of the autonomic nervous system mediated by its cognate α- and β-adrenoceptors in regulating the phenotypic landscape (EMT) of genitourinary organs; and (b) the therapeutic significance of targeting this signaling pathway in benign and malignant urologic disease. Video abstract.
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Affiliation(s)
- M. Archer
- Department of Urology, Icahn School of Medicine at Mount Sinai, 6th Floor, 1425 Madison Avenue, New York, NY 10029 USA
| | - N. Dogra
- Department of Pathology and Molecular and Cell Based Medicine, Icahn School of Medicine at Mount Sinai, New York, NY USA
- Department of Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY USA
| | - Z. Dovey
- Department of Urology, Icahn School of Medicine at Mount Sinai, 6th Floor, 1425 Madison Avenue, New York, NY 10029 USA
| | - T. Ganta
- Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY USA
- Division of Hematology and Medical Oncology, Mount Sinai Hospital, New York, NY USA
| | - H.-S. Jang
- Department of Urology, Icahn School of Medicine at Mount Sinai, 6th Floor, 1425 Madison Avenue, New York, NY 10029 USA
| | - J. A. Khusid
- Department of Urology, Icahn School of Medicine at Mount Sinai, 6th Floor, 1425 Madison Avenue, New York, NY 10029 USA
| | - A. Lantz
- Department of Molecular Medicine and Surgery, Section of Urology, Karolinska Institute, Stockholm, Sweden
- Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden
| | - M. Mihalopoulos
- Department of Urology, Icahn School of Medicine at Mount Sinai, 6th Floor, 1425 Madison Avenue, New York, NY 10029 USA
- Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY USA
| | - J. A. Stockert
- Department of Urology, Icahn School of Medicine at Mount Sinai, 6th Floor, 1425 Madison Avenue, New York, NY 10029 USA
| | - A. Zahalka
- Department of Urology, Icahn School of Medicine at Mount Sinai, 6th Floor, 1425 Madison Avenue, New York, NY 10029 USA
| | - L. Björnebo
- Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden
| | - S. Gaglani
- Department of Urology, Icahn School of Medicine at Mount Sinai, 6th Floor, 1425 Madison Avenue, New York, NY 10029 USA
| | - M. R. Noh
- Department of Urology, Icahn School of Medicine at Mount Sinai, 6th Floor, 1425 Madison Avenue, New York, NY 10029 USA
| | - S. A. Kaplan
- Department of Urology, Icahn School of Medicine at Mount Sinai, 6th Floor, 1425 Madison Avenue, New York, NY 10029 USA
| | - R. Mehrazin
- Department of Urology, Icahn School of Medicine at Mount Sinai, 6th Floor, 1425 Madison Avenue, New York, NY 10029 USA
- Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY USA
| | - K. K. Badani
- Department of Urology, Icahn School of Medicine at Mount Sinai, 6th Floor, 1425 Madison Avenue, New York, NY 10029 USA
- Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY USA
| | - P. Wiklund
- Department of Urology, Icahn School of Medicine at Mount Sinai, 6th Floor, 1425 Madison Avenue, New York, NY 10029 USA
- Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY USA
| | - K. Tsao
- Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY USA
- Division of Hematology and Medical Oncology, Mount Sinai Hospital, New York, NY USA
| | - D. J. Lundon
- Department of Urology, Icahn School of Medicine at Mount Sinai, 6th Floor, 1425 Madison Avenue, New York, NY 10029 USA
- Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY USA
| | - N. Mohamed
- Department of Urology, Icahn School of Medicine at Mount Sinai, 6th Floor, 1425 Madison Avenue, New York, NY 10029 USA
- Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY USA
| | - F. Lucien
- Department of Urology, Mayo Clinic, Rochester, MN USA
| | - B. Padanilam
- Department of Urology, Icahn School of Medicine at Mount Sinai, 6th Floor, 1425 Madison Avenue, New York, NY 10029 USA
| | - M. Gupta
- Department of Urology, Icahn School of Medicine at Mount Sinai, 6th Floor, 1425 Madison Avenue, New York, NY 10029 USA
| | - A. K. Tewari
- Department of Urology, Icahn School of Medicine at Mount Sinai, 6th Floor, 1425 Madison Avenue, New York, NY 10029 USA
- Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY USA
| | - N. Kyprianou
- Department of Urology, Icahn School of Medicine at Mount Sinai, 6th Floor, 1425 Madison Avenue, New York, NY 10029 USA
- Department of Pathology and Molecular and Cell Based Medicine, Icahn School of Medicine at Mount Sinai, New York, NY USA
- Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY USA
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY USA
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Repurposing of α1-Adrenoceptor Antagonists: Impact in Renal Cancer. Cancers (Basel) 2020; 12:cancers12092442. [PMID: 32872127 PMCID: PMC7564811 DOI: 10.3390/cancers12092442] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 08/20/2020] [Accepted: 08/24/2020] [Indexed: 11/17/2022] Open
Abstract
Renal cancer ranks twelfth in incidence among cancers worldwide. Despite improving outcomes due to better therapeutic options and strategies, prognosis for those with metastatic disease remains poor. Current systemic therapeutic approaches include inhibiting pathways of angiogenesis, immune checkpoint blockade, and mTOR inhibition, but inevitably resistance develops for those with metastatic disease, and novel treatment strategies are urgently needed. Emerging molecular and epidemiological evidence suggests that quinazoline-based α1-adrenoceptor-antagonists may have both chemopreventive and direct therapeutic actions in the treatment of urological cancers, including renal cancer. In human renal cancer cell models, quinazoline-based α1-adrenoceptor antagonists were shown to significantly reduce the invasion and metastatic potential of renal tumors by targeting focal adhesion survival signaling to induce anoikis. Mechanistically these drugs overcome anoikis resistance in tumor cells by targeting cell survival regulators AKT and FAK, disrupting integrin adhesion (α5β1 and α2β1) and engaging extracellular matrix (ECM)-associated tumor suppressors. In this review, we discuss the current evidence for the use of quinazoline-based α1-adrenoceptor antagonists as novel therapies for renal cell carcinoma (RCC) and highlight their potential therapeutic action through overcoming anoikis resistance of tumor epithelial and endothelial cells in metastatic RCC. These findings provide a platform for future studies that will retrospectively and prospectively test repurposing of quinazoline-based α1-adrenoceptor-antagonists for the treatment of advanced RCC and the prevention of metastasis in neoadjuvant, adjuvant, salvage and metastatic settings.
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Gonzalez-Nieves R, Desantis AI, Cutler ML. Rsu1 contributes to regulation of cell adhesion and spreading by PINCH1-dependent and - independent mechanisms. J Cell Commun Signal 2013; 7:279-93. [PMID: 23765260 PMCID: PMC3889256 DOI: 10.1007/s12079-013-0207-5] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2013] [Accepted: 05/28/2013] [Indexed: 01/29/2023] Open
Abstract
Cell adhesion and migration are complex processes that require integrin activation, the formation and dissolution of focal adhesion (FAs), and linkage of actin cytoskeleton to the FAs. The IPP (ILK, PINCH, Parvin) complex regulates FA formation via binding of the adaptor protein ILK to β1 integrin, PINCH and parvin. The signaling protein Rsu1 is linked to the complex via binding PINCH1. The role of Rsu1 and PINCH1 in adhesion and migration was examined in non-transformed mammary epithelial cells. Confocal microscopy revealed that the depletion of either Rsu1 or PINCH1 by siRNA in MCF10A cells decreased the number of focal adhesions and altered the distribution and localization of β1 integrin, vinculin, talin and paxillin without affecting the levels of FA protein expression. This correlated with reduced adhesion, failure to spread or migrate in response to EGF and a loss of actin stress fibers and caveolae. In addition, constitutive phosphorylation of actin regulatory proteins occurred in the absence of PINCH1. The depletion of Rsu1 caused significant reduction in PINCH1 implying that Rsu1 may function by regulating levels of PINCH1. However, while both Rsu1- or PINCH1-depleted cells retained the ability to activate adhesion signaling in response to EGF stimulation, only Rsu1 was required for EGF-induced p38 Map Kinase phosphorylation and ATF2 activation, suggesting an Rsu1 function independent from the IPP complex. Reconstitution of Rsu1-depleted cells with an Rsu1 mutant that does not bind to PINCH1 failed to restore FAs or migration but did promote spreading and constitutive p38 activation. These data show that Rsu1-PINCH1 association with ILK and the IPP complex is required for regulation of adhesion and migration but that Rsu1 has a critical role in linking integrin-induced adhesion to activation of p38 Map kinase signaling and cell spreading. Moreover, it suggests that Rsu1 may regulate p38 signaling from the IPP complex affecting other functions including survival.
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Affiliation(s)
- Reyda Gonzalez-Nieves
- Department of Pathology, F. Edward Hebert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD, 20814, USA
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Zhao G, Guo LL, Xu JY, Yang H, Huang MX, Xiao G. Integrin-linked kinase in gastric cancer cell attachment, invasion and tumor growth. World J Gastroenterol 2011; 17:3487-96. [PMID: 21941415 PMCID: PMC3163246 DOI: 10.3748/wjg.v17.i30.3487] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2010] [Revised: 02/15/2011] [Accepted: 02/22/2011] [Indexed: 02/06/2023] Open
Abstract
AIM: To investigate the effects of integrin-linked kinase (ILK) on gastric cancer cells both in vitro and in vivo.
METHODS: ILK small interfering RNA (siRNA) was transfected into human gastric cancer BGC-823 cells and ILK expression was monitored by real-time quantitative polymerase chain reaction, Western blotting analysis and immunocytochemistry. Cell attachment, proliferation, invasion, microfilament dynamics and the secretion of vascular endothelial growth factor (VEGF) were also measured. Gastric cancer cells treated with ILK siRNA were subcutaneously transplanted into nude mice and tumor growth was assessed.
RESULTS: Both ILK mRNA and protein levels were significantly down-regulated by ILK siRNA in human gastric cancer cells. This significantly inhibited cell attachment, proliferation and invasion. The knockdown of ILK also disturbed F-actin assembly and reduced VEGF secretion in conditioned medium by 40% (P < 0.05). Four weeks after injection of ILK siRNA-transfected gastric cancer cells into nude mice, tumor volume and weight were significantly reduced compared with that of tumors induced by cells treated with non-silencing siRNA or by untreated cells (P < 0.05).
CONCLUSION: Targeting ILK with siRNA suppresses the growth of gastric cancer cells both in vitro and in vivo. ILK plays an important role in gastric cancer progression.
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Sakamoto S, Schwarze S, Kyprianou N. Anoikis disruption of focal adhesion-Akt signaling impairs renal cell carcinoma. Eur Urol 2011; 59:734-44. [PMID: 21269758 DOI: 10.1016/j.eururo.2010.12.038] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2010] [Accepted: 12/30/2010] [Indexed: 10/18/2022]
Abstract
BACKGROUND Quinazoline-based α1-adrenoceptor antagonists suppress tumor growth by inducing apoptosis via an α1-adrenoceptor-independent action. Anoikis is a unique mode of apoptosis consequential to insufficient cell-matrix interactions. OBJECTIVE This study investigated the apoptotic effect of novel quinazoline-based compounds on human renal cancer cells. DESIGN, SETTING, AND PARTICIPANTS Two cell lines were used: renal cell carcinoma (RCC) 786-0, harboring a von Hippel-Lindau (VHL) tumor-suppressor gene mutation with a highly angiogenic phenotype, and Caki cells (no VHL mutation). MEASUREMENTS The lead compound DZ-50 (10 μM) led to significant inhibition of tumor-cell adhesion, migration, and invasion at a lower dose than doxazosin (25 μM) in both RCC lines. RESULTS AND LIMITATIONS Doxazosin induced death-receptor-mediated apoptosis, while DZ-50 led to anoikis via targeting of the focal adhesion complex and AKT signaling that subsequently increased RCC susceptibility to caspase-8-mediated apoptosis. Both quinazoline compounds, doxazosin and DZ-50, significantly reduced RCC metastatic potential in vivo. CONCLUSIONS Quinazoline-based drugs trigger anoikis in RCC by targeting the focal adhesion survival signaling. This potent antitumor action against human RCC suggests a novel quinazoline-based therapy targeting renal cancer.
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Affiliation(s)
- Shinichi Sakamoto
- Department of Surgery, University of Kentucky College of Medicine, Lexington, KY, USA
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Sakamoto S, Kyprianou N. Targeting anoikis resistance in prostate cancer metastasis. Mol Aspects Med 2010; 31:205-14. [PMID: 20153362 PMCID: PMC2988681 DOI: 10.1016/j.mam.2010.02.001] [Citation(s) in RCA: 139] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2009] [Accepted: 02/06/2010] [Indexed: 01/20/2023]
Abstract
Anoikis is a mode of apoptotic cell death, consequential to insufficient cell-matrix interactions and a critical player in tumor angiogenesis and metastasis. The events involved in tumor cell progression toward metastasis potential are mediated by integrins, which upon engagement with components of the extracellular matrix (ECM), reorganize to form adhesion complexes. Targeting apoptotic players is of immense therapeutic significance since resistance to apoptosis is not only critical in conferring therapeutic failure to standard treatment strategies, but anoikis (apoptosis upon loss of anchorage and detachment from ECM) also plays an important role in angiogenesis and metastasis. The ability to survive in the absence of adhesion to the ECM, enables tumor cells to disseminate from the primary tumor site, invade a distant site and establish a metastatic lesion. Tumor cells can escape from detachment-induced apoptosis by controlling anoikis pathways, including the extrinsic death receptor pathway and the ECM-integrin mediated cell survival pathway. Considering the functional promiscuity of individual signaling effectors, it is critical to dissect the molecular networks mechanistically driving tumor cells to evade anoikis and embark on a metastatic spread. Resistance to die via anoikis dictates tumor cell survival and provides a molecular basis for therapeutic targeting of metastatic prostate cancer. Further dissection of critical anoikis signaling events will enable the therapeutic optimization of anoikis targeting to impair prostate cancer metastasis prior to its initiation. This review will discuss the molecular understanding of anoikis regulation in the tumor microenvironment and the in vivo pharmacological implementation of a novel class of antitumor-drugs to optimize apoptotic-based therapeutic targeting, bypassing anoikis-resistance to impair prostate cancer progression to metastasis. Potential combination strategies targeting tumor vascularity (via anoikis) and impairing tumor initiation (via "classic" apoptosis), provide strong therapeutic promise for metastatic prostate cancer by preventing the onset of metastasis.
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Affiliation(s)
- Shinichi Sakamoto
- Department of Surgery/Urology, University of Kentucky College of Medicine, Lexington, KY, USA
| | - Natasha Kyprianou
- Department of Surgery/Urology, University of Kentucky College of Medicine, Lexington, KY, USA
- Department of Molecular & Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY, USA
- Department of Markey Cancer Center, University of Kentucky College of Medicine, Lexington, KY, USA
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Sakamoto S, McCann RO, Dhir R, Kyprianou N. Talin1 promotes tumor invasion and metastasis via focal adhesion signaling and anoikis resistance. Cancer Res 2010; 70:1885-95. [PMID: 20160039 PMCID: PMC2836205 DOI: 10.1158/0008-5472.can-09-2833] [Citation(s) in RCA: 173] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Talin1 is a focal adhesion complex protein that regulates integrin interactions with ECM. This study investigated the significance of talin1 in prostate cancer progression to metastasis in vitro and in vivo. Talin1 overexpression enhanced prostate cancer cell adhesion, migration, and invasion by activating survival signals and conferring resistance to anoikis. ShRNA-mediated talin1 loss led to a significant suppression of prostate cancer cell migration and transendothelial invasion in vitro and a significant inhibition of prostate cancer metastasis in vivo. Talin1-regulated cell survival signals via phosphorylation of focal adhesion complex proteins, such as focal adhesion kinase and Src, and downstream activation of AKT. Targeting AKT activation led to a significant reduction of talin1-mediated prostate cancer cell invasion. Furthermore, talin1 immunoreactivity directly correlated with prostate tumor progression to metastasis in the transgenic adenocarcinoma mouse prostate mouse model. Talin1 profiling in human prostate specimens revealed a significantly higher expression of cytoplasmic talin1 in metastatic tissue compared with primary prostate tumors (P < 0.0001). These findings suggest (a) a therapeutic significance of disrupting talin1 signaling/focal adhesion interactions in targeting metastatic prostate cancer and (b) a potential value for talin1 as a marker of tumor progression to metastasis.
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Affiliation(s)
- Shinichi Sakamoto
- Department of Surgery/Urology, University of Kentucky College of Medicine
| | - Richard O. McCann
- Department of Mercer University School of Medicine, Division of Basic Medical Sciences, Macon, GA
| | - Rajiv Dhir
- Department of Pathology, University of Pittsburgh Medical Center, Pittsburgh, PA
| | - Natasha Kyprianou
- Department of Surgery/Urology, University of Kentucky College of Medicine
- Department of Molecular & Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY
- Markey Cancer Center, University of Kentucky College of Medicine, Lexington, KY
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White DE, Coutu P, Shi YF, Tardif JC, Nattel S, St Arnaud R, Dedhar S, Muller WJ. Targeted ablation of ILK from the murine heart results in dilated cardiomyopathy and spontaneous heart failure. Genes Dev 2006; 20:2355-60. [PMID: 16951252 PMCID: PMC1560410 DOI: 10.1101/gad.1458906] [Citation(s) in RCA: 136] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
A requirement for integrin-mediated adhesion in cardiac physiology is revealed through targeted deletion of integrin-associated genes in the murine heart. Here we show that targeted ablation of the integrin-linked kinase (ILK) expression results in spontaneous cardiomyopathy and heart failure by 6 wk of age. Deletion of ILK results in disaggregation of cardiomyocytes, associated with disruption of adhesion signaling through the beta1-integrin/FAK (focal adhesion kinase) complex. Importantly, the loss of ILK is accompanied by a reduction in cardiac Akt phosphorylation, which normally provides a protective response against stress. Together, these results suggest that ILK plays a central role in protecting the mammalian heart against cardiomyopathy and failure.
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Affiliation(s)
- Donald E White
- Department of Biochemistry and Department of Medicine, McGill University, Montreal, Canada H3A 1A1
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Hannigan G, Troussard AA, Dedhar S. Integrin-linked kinase: a cancer therapeutic target unique among its ILK. Nat Rev Cancer 2005; 5:51-63. [PMID: 15630415 DOI: 10.1038/nrc1524] [Citation(s) in RCA: 492] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Cancer development requires the acquisition of several capabilities that include increased replicative potential, anchorage and growth-factor independence, evasion of apoptosis, angiogenesis, invasion of surrounding tissues and metastasis. One protein that has emerged as promoting many of these phenotypes when dysregulated is integrin-linked kinase (ILK), a unique intracellular adaptor and kinase that links the cell-adhesion receptors, integrins and growth factors to the actin cytoskeleton and to a range of signalling pathways. The recent findings of increased levels of ILK in various cancers, and that inhibition of ILK expression and activity is antitumorigenic, makes ILK an attractive target for cancer therapeutics.
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Affiliation(s)
- Gregory Hannigan
- Cancer Research Program, Hospital for Sick Children, and Department of Laboratory Medicine and Pathobiology, University of Toronto, Ontario, Canada
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Wu C. The PINCH-ILK-parvin complexes: assembly, functions and regulation. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2004; 1692:55-62. [PMID: 15246679 DOI: 10.1016/j.bbamcr.2004.01.006] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Received: 11/03/2003] [Accepted: 01/23/2004] [Indexed: 01/18/2023]
Abstract
Cell-extracellular matrix (ECM) adhesion is mediated by transmembrane cell adhesion receptors (e.g., integrins) and receptor proximal cytoplasmic proteins. Over the past several years, studies using biochemical, structural, cell biological and genetic approaches have provided important evidence suggesting crucial roles of integrin-linked kinase (ILK), PINCH and CH-ILKBP/actopaxin/affixin/parvin (abbreviated as parvin herein) in ECM control of cell behavior. One general theme emerging from these studies is that the formation of ternary protein complexes consisting of ILK, PINCH and parvin is pivotal to the functions of PINCH, ILK and parvin proteins. In addition, recent studies have begun to uncover the molecular mechanisms underlying the assembly, functions and regulation of the PINCH-ILK-parvin (PIP) complexes. The PIP complexes provide crucial physical linkages between integrins and the actin cytoskeleton and transduce diverse signals from ECM to intracellular effectors. Among the challenges of future studies are to define the functions of different PIP complexes in various cellular processes, identify additional partners of the PIP complexes that regulate and/or mediate the functions of the PIP complexes, and determine the roles of the PIP complexes in the pathogenesis of human diseases involving abnormal cell-ECM adhesion and signaling.
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Affiliation(s)
- Chuanyue Wu
- Department of Pathology, University of Pittsburgh, 707B Scaife Hall, 3550 Terrace Street, PA 15261, USA.
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Oloumi A, McPhee T, Dedhar S. Regulation of E-cadherin expression and beta-catenin/Tcf transcriptional activity by the integrin-linked kinase. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2004; 1691:1-15. [PMID: 15053919 DOI: 10.1016/j.bbamcr.2003.12.002] [Citation(s) in RCA: 136] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2003] [Revised: 11/28/2003] [Accepted: 12/04/2003] [Indexed: 01/03/2023]
Abstract
Integrin-linked kinase (ILK) is a serine/threonine protein kinase which interacts with the cytoplasmic domains of beta1 and beta3 integrins. ILK structure and its localization at the focal adhesion allows it not only to interact with different structural proteins, but also to mediate many different signalling pathways. Extracellular matrices (ECM) and growth factors each stimulate ILK signalling. Constitutive activation of ILK in epithelial cells results in oncogenic phenotypes such as disruption of cell extracellular matrix and cell to cell interactions, suppression of suspension-induced apoptosis, and induction of anchorage independent cell growth and cell cycle progression. More specifically, pathological overexpression of ILK results in down-regulation of E-cadherin expression, and nuclear accumulation of beta-catenin, leading to the subsequent activation of the beta-catenin/Tcf transcription complex, the downstream components of the Wnt signalling pathway. Here we review the data implicating ILK in the regulation of these two signalling pathways, and discuss recent novel insights into the molecular basis and requirement of ILK in the process of epithelial to mesenchymal transformation (EMT).
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Affiliation(s)
- Arusha Oloumi
- British Columbia Cancer Agency and Jack Bell Research Centre, University of British Columbia, Vancouver Hospital, 2660 Oak St. Vancouver, BC, Canada V6H 3Z6
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Zhang Y, Chen K, Guo L, Wu C. Characterization of PINCH-2, a new focal adhesion protein that regulates the PINCH-1-ILK interaction, cell spreading, and migration. J Biol Chem 2002; 277:38328-38. [PMID: 12167643 DOI: 10.1074/jbc.m205576200] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Integrin-linked kinase (ILK) is a multidomain protein that plays important roles at cell-extracellular matrix (ECM) adhesion sites. We describe here a new LIM-domain containing protein (termed as PINCH-2) that forms a complex with ILK. PINCH-2 is co-expressed with PINCH-1 (previously known as PINCH), another member of the PINCH protein family, in a variety of human cells. Immunofluorescent staining of cells with PINCH-2-specific antibodies show that PINCH-2 localizes to both cell-ECM contact sites and the nucleus. Deletion of the first LIM (LIM1) domain of PINCH-2 abolished the ability of PINCH-2 to form a complex with ILK. The ILK-binding defective LIM1-deletion mutant, unlike the wild type PINCH-2 or the ILK-binding competent LIM5-deletion mutant, was incapable of localizing to cell-ECM contact sites, suggesting that ILK binding is required for this process. Importantly, the PINCH-2-ILK and PINCH-1-ILK interactions are mutually exclusive. Overexpression of PINCH-2 significantly inhibited the PINCH-1-ILK interaction and reduced cell spreading and migration. These results identify a novel nuclear and focal adhesion protein that associates with ILK and reveals an important role of PINCH-2 in the regulation of the PINCH-1-ILK interaction, cell shape change, and migration.
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Affiliation(s)
- Yongjun Zhang
- Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA
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Melchior C, Kreis S, Janji B, Kieffer N. Promoter characterization and genomic organization of the gene encoding integrin-linked kinase 1. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1575:117-22. [PMID: 12020826 DOI: 10.1016/s0167-4781(02)00247-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Integrin-linked kinase (ILK)-1 is a 59-kDa serine-threonine protein kinase, which associates with the cytoplasmic domain of beta 1, beta 2 and beta 3 integrins and acts as a receptor proximal kinase regulating integrin-mediated signal transduction. We have recently identified an isoform of ILK (ILK-2), which is expressed, in a TGF-beta 1-dependent manner, in a highly invasive tumor cell line but not in normal adult tissues. In contrast, ILK-1 is ubiquitously expressed in normal tissues and is up-regulated in various tumors independent of TGF-beta 1. Here, we report the structural organization and the promoter activity of the human ILK-1 gene, contained within a 8.8-kb genomic fragment cloned from a human BAC library. The mature protein is encoded by 13 exons. The last coding exon contains the entire 3' UTR of the ILK-1 gene, which overlaps with the complementary 3' UTR sequence of the TAF2H gene, a TATA box binding protein-associated factor. A major transcriptional initiation start site was found 138 bp upstream of exon 1 in close proximity to a consensus initiator element (Inr). The ILK gene is transcribed by a TATA-less and CAAT-less promoter with typical features of housekeeping genes. The promoter activity was characterized by a luciferase reporter assay and the minimal sequence conferring promoter activity was 349 bp in size and located immediately upstream of exon 1.
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Affiliation(s)
- Chantal Melchior
- Laboratoire Franco-Luxembourgeois de Recherche Biomédicale, CNRS/CRP-Santé, University Center, 162A, avenue de la Faiencerie L-1511, Luxembourg, Luxembourg
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Nikolopoulos SN, Turner CE. Integrin-linked kinase (ILK) binding to paxillin LD1 motif regulates ILK localization to focal adhesions. J Biol Chem 2001; 276:23499-505. [PMID: 11304546 DOI: 10.1074/jbc.m102163200] [Citation(s) in RCA: 169] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Paxillin is a focal adhesion adapter protein involved in integrin signaling. Paxillin LD motifs bind several focal adhesion proteins including the focal adhesion kinase, vinculin, the Arf-GTPase-activating protein paxillin-kinase linker, and the newly identified actin-binding protein actopaxin. Microsequencing of peptides derived from a 50-kDa paxillin LD1 motif-binding protein revealed 100% identity with integrin-linked kinase (ILK)-1, a serine/threonine kinase that has been implicated in integrin, growth factor, and Wnt signaling pathways. Cloning of ILK from rat smooth muscle cells generated a cDNA that exhibited 99.6% identity at the amino acid level with human ILK-1. A monoclonal antibody raised against a region of the carboxyl terminus of ILK, which is identical in rat and human ILK-1 protein, recognized a 50-kDa protein in all cultured cells and tissues examined. Binding experiments showed that ILK binds directly to the paxillin LD1 motif in vitro. Co-immunoprecipitation from fibroblasts confirmed that the association between paxillin and ILK occurs in vivo in both adherent cells and cells in suspension. Immunofluorescence microscopy of fibroblasts demonstrated that endogenous ILK as well as transfected green fluorescent protein-ILK co-localizes with paxillin in focal adhesions. Analysis of the deduced amino acid sequence of ILK identified a paxillin-binding subdomain in the carboxyl terminus of ILK. In contrast to wild-type ILK, paxillin-binding subdomain mutants of ILK were unable to bind to the paxillin LD1 motif in vitro and failed to localize to focal adhesions. Thus, paxillin binding is necessary for efficient focal adhesion targeting of ILK and may therefore impact the role of ILK in integrin-mediated signal transduction events.
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Affiliation(s)
- S N Nikolopoulos
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York 13210, USA
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Huang Y, Li J, Zhang Y, Wu C. The roles of integrin-linked kinase in the regulation of myogenic differentiation. J Cell Biol 2000; 150:861-72. [PMID: 10953009 PMCID: PMC2175275 DOI: 10.1083/jcb.150.4.861] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2000] [Accepted: 07/07/2000] [Indexed: 01/14/2023] Open
Abstract
Myogenic differentiation is a highly orchestrated, multistep process that is coordinately regulated by growth factors and cell adhesion. We show here that integrin-linked kinase (ILK), an intracellular integrin- and PINCH-binding serine/threonine protein kinase, is an important regulator of myogenic differentiation. ILK is abundantly expressed in C2C12 myoblasts, both before and after induction of terminal myogenic differentiation. However, a noticeable amount of ILK in the Triton X-100-soluble cellular fractions is significantly reduced during terminal myogenic differentiation, suggesting that ILK is involved in cellular control of myogenic differentiation. To further investigate this, we have overexpressed the wild-type and mutant forms of ILK in C2C12 myoblasts. Overexpression of ILK in the myoblasts inhibited the expression of myogenic proteins (myogenin, MyoD, and myosin heavy chain) and the subsequent formation of multinucleated myotubes. Furthermore, mutations that eliminate either the PINCH-binding or the kinase activity of ILK abolished its ability to inhibit myogenic protein expression and allowed myotube formation. Although overexpression of the ILK mutants is permissive for the initiation of terminal myogenic differentiation, the myotubes derived from myoblasts overexpressing the ILK mutants frequently exhibited an abnormal morphology (giant myotubes containing clustered nuclei), suggesting that ILK functions not only in the initial decision making process, but also in later stages (fusion or maintaining myotube integrity) of myogenic differentiation. Additionally, we show that overexpression of ILK, but not that of the PINCH-binding defective or the kinase-deficient ILK mutants, prevents inactivation of MAP kinase, which is obligatory for the initiation of myogenic differentiation. Finally, inhibition of MAP kinase activation reversed the ILK-induced suppression of myogenic protein expression. Thus, ILK likely influences the initial decision making process of myogenic differentiation by regulation of MAP kinase activation.
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Affiliation(s)
- Yao Huang
- Department of Cell Biology, University of Alabama at Birmingham, Birmingham, Alabama 35294-0019
- The Cell Adhesion and Matrix Research Center, University of Alabama at Birmingham, Birmingham, Alabama 35294-0019
| | - Ji Li
- Department of Cell Biology, University of Alabama at Birmingham, Birmingham, Alabama 35294-0019
- The Cell Adhesion and Matrix Research Center, University of Alabama at Birmingham, Birmingham, Alabama 35294-0019
| | - Yongjun Zhang
- Department of Cell Biology, University of Alabama at Birmingham, Birmingham, Alabama 35294-0019
- The Cell Adhesion and Matrix Research Center, University of Alabama at Birmingham, Birmingham, Alabama 35294-0019
| | - Chuanyue Wu
- Department of Cell Biology, University of Alabama at Birmingham, Birmingham, Alabama 35294-0019
- The Cell Adhesion and Matrix Research Center, University of Alabama at Birmingham, Birmingham, Alabama 35294-0019
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16
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Janji B, Melchior C, Vallar L, Kieffer N. Cloning of an isoform of integrin-linked kinase (ILK) that is upregulated in HT-144 melanoma cells following TGF-beta1 stimulation. Oncogene 2000; 19:3069-77. [PMID: 10871859 DOI: 10.1038/sj.onc.1203640] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We have shown previously that integrin-linked kinase (ILK) is upregulated in human HT-144 melanoma cells following TGF-beta1 stimulation. Using mRNA from TGF-beta1 stimulated HT-144 cells and reverse transcriptase polymerase chain reaction, we have isolated a cDNA encoding a protein highly homologous to ILK. Sequencing of the full-length 1359 base pair cDNA and polypeptide translation revealed that this protein, designated ILK-2, differs from the known ILK (hereafter called ILK-1) by only four amino acids, while the cDNA sequence diverges by 102 nucleotides, thus excluding that ILK-2 is an allelic variant of ILK-1. Expression of ILK-2 mRNA was observed in metastatic human HT-144 melanoma and HT-1080 fibrosarcoma cell lines, but not in normal human tissues. Moreover, stimulation of HT-144 cells with TGF-beta1, but not with EGF, PDGF-AB or insulin, induced a selective overexpression of ILK-2 mRNA as compared to ILK-1 mRNA. Bacterially-expressed GST/ILK-2 autophosphorylated and labeled myelin basic protein as well as a recombinant GST/beta3 integrin cytoplasmic tail peptide. Transfection of either ILK-2 or ILK-1 cDNA into the non-metastatic melanoma cell line SK-Mel-2, expressing exclusively ILK-1, induced anchorage independent cell growth and cell proliferation, as demonstrated by growth in soft agar. Our data provide evidence that ILK-2 is a new isoform of ILK-1 that is expressed in some highly invasive tumor cell lines but not in normal adult human tissues and whose expression is regulated by TGF-beta1.
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Affiliation(s)
- B Janji
- Laboratoire Franco-Luxembourgeois de Recherche Biomedicale (CRP-Sante/CNRS), University Center, L-1511 Luxembourg, Grand-Duchy of Luxembourg
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17
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Wu C. Integrin-linked kinase and PINCH: partners in regulation of cell-extracellular matrix interaction and signal transduction. J Cell Sci 1999; 112 ( Pt 24):4485-9. [PMID: 10574698 DOI: 10.1242/jcs.112.24.4485] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Integrin-linked kinase (ILK) is a focal adhesion serine/threonine protein kinase that is emerging as a key signaling protein functioning at one of the early convergence points of integrin- and growth factor-signaling pathways. ILK binds to PINCH through the N-terminal ankyrin (ANK) repeat domain and the PINCH binding is crucial for focal adhesion localization of ILK. The ILK-PINCH interaction also connects ILK to Nck-2, an SH2-SH3-containing adaptor protein that interacts with components of growth factor and small GTPase signaling pathways. The kinase activity of ILK is regulated by both cell adhesion and growth factors in a phosphoinositide 3-kinase (PI3K)-dependent manner. ILK phosphorylates downstream targets such as protein kinase B (PKB, also known as Akt) and glycogen synthase kinase 3 (GSK-3) and regulates their activities. Overexpression of ILK in epithelial cells leads to striking morphological changes mimicking epithelial-mesenchymal transition, including upregulation of integrin-mediated fibronectin matrix assembly and downregulation of cell-cell adhesions. Furthermore, ILK regulates nuclear translocation of (beta)-catenin and gene expression, and promotes cell cycle progression and tumor formation. Recent genetic studies in Drosophila melanogaster and Caenorhabditis elegans have shown that lack of expression of ILK or PINCH results in phenotypes resembling those of integrin-null mutants, which demonstrates that ILK and PINCH are indispensable for integrin function during embryonic development.
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Affiliation(s)
- C Wu
- Department of Cell Biology and The Cell Adhesion and Matrix Research Center, University of Alabama at Birmingham, Birmingham, AL 35294-0019, USA.
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Li F, Zhang Y, Wu C. Integrin-linked kinase is localized to cell-matrix focal adhesions but not cell-cell adhesion sites and the focal adhesion localization of integrin-linked kinase is regulated by the PINCH-binding ANK repeats. J Cell Sci 1999; 112 ( Pt 24):4589-99. [PMID: 10574708 DOI: 10.1242/jcs.112.24.4589] [Citation(s) in RCA: 136] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Integrin-linked kinase (ILK) is a ubiquitously expressed protein serine/threonine kinase that has been implicated in integrin-, growth factor- and Wnt-signaling pathways. In this study, we show that ILK is a constituent of cell-matrix focal adhesions. ILK was recruited to focal adhesions in all types of cells examined upon adhesion to a variety of extracellular matrix proteins. By contrast, ILK was absent in E-cadherin-mediated cell-cell adherens junctions. In previous studies, we have identified PINCH, a protein consisting of five LIM domains, as an ILK binding protein. We demonstrate in this study that the ILK-PINCH interaction requires the N-terminal-most ANK repeat (ANK1) of ILK and one (the C-terminal) of the two zinc-binding modules within the LIM1 domain of PINCH. The ILK ANK repeats domain, which is capable of interacting with PINCH in vitro, could also form a complex with PINCH in vivo. However, the efficiency of the complex formation or the stability of the complex was markedly reduced in the absence of the C-terminal domain of ILK. The PINCH binding defective ANK1 deletion ILK mutant, unlike the wild-type ILK, was unable to localize and cluster in focal adhesions, suggesting that the interaction with PINCH is necessary for focal adhesion localization and clustering of ILK. The N-terminal ANK repeats domain, however, is not sufficient for mediating focal adhesion localization of ILK, as an ILK mutant containing the ANK repeats domain but lacking the C-terminal integrin binding site failed to localize in focal adhesions. These results suggest that focal adhesions are a major subcellular compartment where ILK functions in intracellular signal transduction, and provide important evidence for a critical role of PINCH and integrins in regulating ILK cellular function.
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Affiliation(s)
- F Li
- Department of Cell Biology and The Cell Adhesion and Matrix Research Center, University of Alabama at Birmingham, Birmingham, AL 35294-0019, USA
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19
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Dedhar S, Williams B, Hannigan G. Integrin-linked kinase (ILK): a regulator of integrin and growth-factor signalling. Trends Cell Biol 1999; 9:319-23. [PMID: 10407411 DOI: 10.1016/s0962-8924(99)01612-8] [Citation(s) in RCA: 200] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Interaction of cells with the extracellular matrix (ECM) results in the regulation of cell growth, differentiation and migration by coordinated signal transduction through integrins and growth-factor receptors. Integrins achieve signalling by interacting with intracellular effectors that couple integrins and growth-factor receptors to downstream components. One well-studied effector is focal-adhesion kinase (FAK), but recently another protein kinase, integrin-linked kinase (ILK), has been identified as a receptor-proximal effector of integrin and growth-factor signalling. ILK appears to interact with and be influenced by a number of different signalling pathways, and this provides new routes for integrin-mediated signalling. This article discusses ILK structure and function and recent genetic and biochemical evidence about the role of ILK in signal transduction.
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Affiliation(s)
- S Dedhar
- BC Cancer Agency and Dept of Biochemistry and Molecular Biology, University of BC, Jack Bell Research Centre, 2660 Oak Street, Vancouver, B.C., Canada V6H 3ZH.
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Tu Y, Li F, Goicoechea S, Wu C. The LIM-only protein PINCH directly interacts with integrin-linked kinase and is recruited to integrin-rich sites in spreading cells. Mol Cell Biol 1999; 19:2425-34. [PMID: 10022929 PMCID: PMC84035 DOI: 10.1128/mcb.19.3.2425] [Citation(s) in RCA: 233] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
PINCH is a widely expressed and evolutionarily conserved protein comprising primarily five LIM domains, which are cysteine-rich consensus sequences implicated in mediating protein-protein interactions. We report here that PINCH is a binding protein for integrin-linked kinase (ILK), an intracellular serine/threonine protein kinase that plays important roles in the cell adhesion, growth factor, and Wnt signaling pathways. The interaction between ILK and PINCH has been consistently observed under a variety of experimental conditions. They have interacted in yeast two-hybrid assays, in solution, and in solid-phase-based binding assays. Furthermore, ILK, but not vinculin or focal adhesion kinase, has been coisolated with PINCH from mammalian cells by immunoaffinity chromatography, indicating that PINCH and ILK associate with each other in vivo. The PINCH-ILK interaction is mediated by the N-terminal-most LIM domain (LIM1, residues 1 to 70) of PINCH and multiple ankyrin (ANK) repeats located within the N-terminal domain (residues 1 to 163) of ILK. Additionally, biochemical studies indicate that ILK, through the interaction with PINCH, is capable of forming a ternary complex with Nck-2, an SH2/SH3-containing adapter protein implicated in growth factor receptor kinase and small GTPase signaling pathways. Finally, we have found that PINCH is concentrated in peripheral ruffles of cells spreading on fibronectin and have detected clusters of PINCH that are colocalized with the alpha5beta1 integrins. These results demonstrate a specific protein recognition mechanism utilizing a specific LIM domain and multiple ANK repeats and suggest that PINCH functions as an adapter protein connecting ILK and the integrins with components of growth factor receptor kinase and small GTPase signaling pathways.
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Affiliation(s)
- Y Tu
- Department of Cell Biology and The Cell Adhesion and Matrix Research Center, University of Alabama at Birmingham, Birmingham, Alabama 35294-0019, USA
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Xie W, Li F, Kudlow JE, Wu C. Expression of the integrin-linked kinase (ILK) in mouse skin: loss of expression in suprabasal layers of the epidermis and up-regulation by erbB-2. THE AMERICAN JOURNAL OF PATHOLOGY 1998; 153:367-72. [PMID: 9708797 PMCID: PMC1852995 DOI: 10.1016/s0002-9440(10)65580-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 05/05/1998] [Indexed: 11/21/2022]
Abstract
Integrin-linked kinase (ILK) is a newly identified serine/threonine protein kinase implicated in integrin signaling. To investigate the functions of ILK in vivo, we have analyzed the expression and regulation of ILK in the skin, in which proper control of cell-extracellular matrix interactions and cell proliferation is essential for its normal development and homeostasis. We report here that ILK is abundantly expressed throughout the extracellular matrix-rich dermis. ILK mRNA was also detected in the hair follicles and the basal cells of the interfollicular epidermis. However, ILK expression is lost in the suprabasal layers of keratinocytes that are undergoing terminal differentiation. PINCH, an ILK-binding protein, exhibited a similar expression pattern in the skin. Recent studies have indicated that erbB-2, a member of the epidermal growth factor receptor family, plays a pivotal role in epidermal growth, differentiation, and hair follicle morphogenesis. Using a transgenic mouse system in which an activated erbB-2 is overexpressed in the epidermis, we show that ILK expression is regulated by erbB-2. The in vivo expression and regulation patterns of ILK, together with its biochemical activities, suggest an important role of ILK in coordinating the integrin signaling pathways and the growth factor signaling pathways in the development of the skin and the pathogenesis of skin diseases.
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Affiliation(s)
- W Xie
- Department of Cell Biology, University of Alabama at Birmingham, 35294-0019, USA
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