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Iskandar M, Xiao Barbero M, Jaber M, Chen R, Gomez-Guevara R, Cruz E, Westerheide S. A Review of Telomere Attrition in Cancer and Aging: Current Molecular Insights and Future Therapeutic Approaches. Cancers (Basel) 2025; 17:257. [PMID: 39858038 PMCID: PMC11764024 DOI: 10.3390/cancers17020257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2024] [Revised: 01/09/2025] [Accepted: 01/11/2025] [Indexed: 01/27/2025] Open
Abstract
BACKGROUND/OBJECTIVES As cells divide, telomeres shorten through a phenomenon known as telomere attrition, which leads to unavoidable senescence of cells. Unprotected DNA exponentially increases the odds of mutations, which can evolve into premature aging disorders and tumorigenesis. There has been growing academic and clinical interest in exploring this duality and developing optimal therapeutic strategies to combat telomere attrition in aging and cellular immortality in cancer. The purpose of this review is to provide an updated overview of telomere biology and therapeutic tactics to address aging and cancer. METHODS We used the Rayyan platform to review the PubMed database and examined the ClinicalTrial.gov registry to gain insight into clinical trials and their results. RESULTS Cancer cells activate telomerase or utilize alternative lengthening of telomeres to escape telomere shortening, leading to near immortality. Contrarily, normal cells experience telomeric erosion, contributing to premature aging disorders, such as Werner syndrome and Hutchinson-Gilford Progeria, and (2) aging-related diseases, such as neurodegenerative and cardiovascular diseases. CONCLUSIONS The literature presents several promising therapeutic approaches to potentially balance telomere maintenance in aging and shortening in cancer. This review highlights gaps in knowledge and points to the potential of these optimal interventions in preclinical and clinical studies to inform future research in cancer and aging.
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Affiliation(s)
| | | | | | | | | | | | - Sandy Westerheide
- Department of Molecular Biosciences, University of South Florida, 4202 East Fowler Avenue, ISA2015, Tampa, FL 33620, USA; (M.I.); (M.X.B.); (M.J.); (R.C.); (R.G.-G.); (E.C.)
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2
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El-Desoky AM, Ali YBM, Talaat RM. Cytotoxic effect of combining two antisense oligonucleotides against telomerase rna component (hTR and mRNA of centromere protein B (CENP-B) in hepatocellular carcinoma cells. AN ACAD BRAS CIENC 2022; 94:e20200573. [PMID: 35894385 DOI: 10.1590/0001-3765202120200573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 07/03/2020] [Indexed: 11/22/2022] Open
Abstract
Telomerase is a ribonucleoprotein enzyme that plays a crucial role in maintaining the malignancy and is responsible for cellular immortality and tumorigenesis. On another hand, Centromere protein B (CENP-B) plays an important role in cell cycle regulation and helping in the high rate proliferation of cancer cells. Our study is designed to evaluate the effect of using combined antisense oligonucleotides (ASOs) targeting (hTR) and mRNA of CENP-B on liver cancer cells. Compared with a single treatment, combination treatment with Locked Nucleic Acid (LNA) ASO (hTR) and (CENP-B) (6.25 nM from each) exhibit the maximum synergistic cytotoxic effect. hTR and CENP-B mRNA was abrogated while hTERT expression was disappeared. Caspase-3, Bax, and Bcl-2 were not detected, indicating caspase-independent cell death. A significant reduction in [Tumor necrosis factor (TNF-α) and Transforming growth factor (TGF-β)] coincides with elevation in Nitric oxide (NO) secretions was observed. Taken together; our data suggest that combination treatment with LNA ASO (hTR) and (CENP-B) could provide a promising strategy for cancer treatment by controlling many pathways concurrently. This might open a new prospective application of antisense in cancer therapy.
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Affiliation(s)
- Ahmed M El-Desoky
- University of Sadat City (USC), Genetic Engineering and Biotechnology Research Institute (GEBRI), Department of Molecular Biology, PO Box 79 / 22857 Sadat City, Egypt
| | - Yasser B M Ali
- University of Sadat City (USC), Genetic Engineering and Biotechnology Research Institute (GEBRI), Department of Molecular Biology, PO Box 79 / 22857 Sadat City, Egypt
| | - Roba M Talaat
- University of Sadat City (USC), Genetic Engineering and Biotechnology Research Institute (GEBRI), Department of Molecular Biology, PO Box 79 / 22857 Sadat City, Egypt
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3
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Lášek T, Petrová M, Košiová I, Šimák O, Buděšínský M, Kozák J, Snášel J, Vavřina Z, Birkuš G, Rosenberg I, Páv O. 5′-Phosphonate modified oligoadenylates as potent activators of human RNase L. Bioorg Med Chem 2022; 56:116632. [DOI: 10.1016/j.bmc.2022.116632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 01/14/2022] [Accepted: 01/14/2022] [Indexed: 11/30/2022]
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4
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Gala K, Khattar E. Long non-coding RNAs at work on telomeres: Functions and implications in cancer therapy. Cancer Lett 2021; 502:120-132. [PMID: 33450357 DOI: 10.1016/j.canlet.2020.12.036] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2020] [Revised: 12/13/2020] [Accepted: 12/29/2020] [Indexed: 12/27/2022]
Abstract
Long non-coding RNAs (lncRNAs) are known to regulate various biological processes including cancer. Cancer cells possess limitless replicative potential which is attained by telomere length maintenance while normal somatic cells have a limited lifespan because their telomeres shorten with every cell division ultimately triggering replicative senescence. Two lncRNAs have been observed to play a key role in telomere length maintenance. First is the lncRNA TERC (telomerase RNA component) which functions as a template for telomeric DNA synthesis in association with telomerase reverse transcriptase (TERT) which serves as the catalytic component. Together they constitute the telomerase complex which functions as a reverse transcriptase to elongate telomeres. Second lncRNA that helps in regulating telomere length is the telomeric repeat-containing RNA (TERRA) which is transcribed from the subtelomeric region and extends to the telomeric region. TERC and TERRA exhibit important functions in cancer with implications in precision oncology. In this review, we discuss various aspects of these important lncRNAs in humans and their role in cancer along with recent advancements in their anticancer therapeutic application.
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Affiliation(s)
- Kavita Gala
- Sunandan Divatia School of Science, SVKM's NMIMS (Deemed to be) University, Mumbai, 400056, Maharashtra, India
| | - Ekta Khattar
- Sunandan Divatia School of Science, SVKM's NMIMS (Deemed to be) University, Mumbai, 400056, Maharashtra, India.
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5
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Rosen J, Jakobs P, Ale-Agha N, Altschmied J, Haendeler J. Non-canonical functions of Telomerase Reverse Transcriptase - Impact on redox homeostasis. Redox Biol 2020; 34:101543. [PMID: 32502898 PMCID: PMC7267725 DOI: 10.1016/j.redox.2020.101543] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 04/11/2020] [Accepted: 04/13/2020] [Indexed: 02/08/2023] Open
Abstract
Telomerase consists of the catalytic subunit Telomerase Reverse Transcriptase (TERT) and the Telomerase RNA Component. Its canonical function is the prevention of telomere erosion. Over the last years it became evident that TERT is also present in tissues with low replicative potential. Important non-canonical functions of TERT are protection against apoptosis and maintenance of the cellular redox homeostasis in cancer as well as in somatic tissues. Intriguingly, TERT and reactive oxygen species (ROS) are interdependent on each other, with TERT being regulated by changes in the redox balance and itself controlling ROS levels in the cytosol and in the mitochondria. The latter is achieved because TERT is present in the mitochondria, where it protects mitochondrial DNA and maintains levels of anti-oxidative enzymes. Since numerous diseases are associated with oxidative stress, increasing the mitochondrial TERT level could be of therapeutic value.
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Affiliation(s)
- Julia Rosen
- Environmentally-induced Cardiovascular Degeneration, Institute of Clinical Chemistry and Laboratory Diagnostics, Medical Faculty, Heinrich-Heine University Düsseldorf, Germany; IUF-Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany
| | - Philipp Jakobs
- Environmentally-induced Cardiovascular Degeneration, Institute of Clinical Chemistry and Laboratory Diagnostics, Medical Faculty, Heinrich-Heine University Düsseldorf, Germany; IUF-Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany
| | - Niloofar Ale-Agha
- Environmentally-induced Cardiovascular Degeneration, Institute of Clinical Chemistry and Laboratory Diagnostics, Medical Faculty, Heinrich-Heine University Düsseldorf, Germany; IUF-Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany
| | - Joachim Altschmied
- IUF-Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany.
| | - Judith Haendeler
- Environmentally-induced Cardiovascular Degeneration, Institute of Clinical Chemistry and Laboratory Diagnostics, Medical Faculty, Heinrich-Heine University Düsseldorf, Germany; IUF-Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany.
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6
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Telomere Gene Therapy: Polarizing Therapeutic Goals for Treatment of Various Diseases. Cells 2019; 8:cells8050392. [PMID: 31035374 PMCID: PMC6563133 DOI: 10.3390/cells8050392] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 04/22/2019] [Accepted: 04/24/2019] [Indexed: 02/07/2023] Open
Abstract
Modulation of telomerase maintenance by gene therapy must meet two polarizing requirements to achieve different therapeutic outcomes: Anti-aging/regenerative applications require upregulation, while anticancer applications necessitate suppression of various genes integral to telomere maintenance (e.g., telomerase, telomerase RNA components, and shelterin complex). Patients suffering from aging-associated illnesses often exhibit telomere attrition, which promotes chromosomal instability and cellular senescence, thus requiring the transfer of telomere maintenance-related genes to improve patient outcomes. However, reactivation and overexpression of telomerase are observed in 85% of cancer patients; this process is integral to cancer immortality. Thus, telomere-associated genes in the scope of cancer gene therapy must be inactivated or inhibited to induce anticancer effects. These contradicting requirements for achieving different therapeutic outcomes mean that any vector-mediated upregulation of telomere-associated genes must be accompanied by rigorous evaluation of potential oncogenesis. Thus, this review aims to discuss how telomere-associated genes are being targeted or utilized in various gene therapy applications and provides some insight into currently available safety hazard assessments.
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7
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Baena-Del Valle JA, Zheng Q, Esopi DM, Rubenstein M, Hubbard GK, Moncaliano MC, Hruszkewycz A, Vaghasia A, Yegnasubramanian S, Wheelan SJ, Meeker AK, Heaphy CM, Graham MK, De Marzo AM. MYC drives overexpression of telomerase RNA (hTR/TERC) in prostate cancer. J Pathol 2017; 244:11-24. [PMID: 28888037 DOI: 10.1002/path.4980] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2016] [Revised: 08/07/2017] [Accepted: 08/24/2017] [Indexed: 01/21/2023]
Abstract
Telomerase consists of at least two essential elements, an RNA component hTR or TERC that contains the template for telomere DNA addition and a catalytic reverse transcriptase (TERT). While expression of TERT has been considered the key rate-limiting component for telomerase activity, increasing evidence suggests an important role for the regulation of TERC in telomere maintenance and perhaps other functions in human cancer. By using three orthogonal methods including RNAseq, RT-qPCR, and an analytically validated chromogenic RNA in situ hybridization assay, we report consistent overexpression of TERC in prostate cancer. This overexpression occurs at the precursor stage (e.g. high-grade prostatic intraepithelial neoplasia or PIN) and persists throughout all stages of disease progression. Levels of TERC correlate with levels of MYC (a known driver of prostate cancer) in clinical samples and we also show the following: forced reductions of MYC result in decreased TERC levels in eight cancer cell lines (prostate, lung, breast, and colorectal); forced overexpression of MYC in PCa cell lines, and in the mouse prostate, results in increased TERC levels; human TERC promoter activity is decreased after MYC silencing; and MYC occupies the TERC locus as assessed by chromatin immunoprecipitation (ChIP). Finally, we show that knockdown of TERC by siRNA results in reduced proliferation of prostate cancer cell lines. These studies indicate that TERC is consistently overexpressed in all stages of prostatic adenocarcinoma and that its expression is regulated by MYC. These findings nominate TERC as a novel prostate cancer biomarker and therapeutic target. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
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Affiliation(s)
- Javier A Baena-Del Valle
- Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,Department of Pathology and Laboratory Medicine, Fundacion Santa Fe De Bogota University Hospital, Bogota, DC, Colombia
| | - Qizhi Zheng
- Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - David M Esopi
- Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Michael Rubenstein
- Department of Biological Sciences, University of Maryland, Baltimore County, Baltimore, Maryland, USA
| | - Gretchen K Hubbard
- Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Maria C Moncaliano
- Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Andrew Hruszkewycz
- Division of Cancer Treatment and Diagnosis, National Cancer Institute, Bethesda, Maryland, USA
| | - Ajay Vaghasia
- Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Srinivasan Yegnasubramanian
- Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,Departments of Urology and Oncology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,The Brady Urological Research Institute, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Sarah J Wheelan
- Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,Departments of Urology and Oncology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,The Brady Urological Research Institute, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Alan K Meeker
- Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,The Brady Urological Research Institute, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Christopher M Heaphy
- Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,The Brady Urological Research Institute, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Mindy K Graham
- Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,The Brady Urological Research Institute, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Angelo M De Marzo
- Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,Departments of Urology and Oncology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,The Brady Urological Research Institute, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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8
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Mondal A, Chatterji U. Artemisinin Represses Telomerase Subunits and Induces Apoptosis in HPV-39 Infected Human Cervical Cancer Cells. J Cell Biochem 2016; 116:1968-81. [PMID: 25755006 DOI: 10.1002/jcb.25152] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Accepted: 03/02/2015] [Indexed: 12/18/2022]
Abstract
Artemisinin, a plant-derived antimalarial drug with relatively low toxicity on normal cells in humans, has selective anticancer activities in various types of cancers, both in vitro and in vivo. In the present study, we have investigated the anticancer effects of artemisinin in human cervical cancer cells, with special emphasis on its role in inducing apoptosis and repressing cell proliferation by inhibiting the telomerase subunits, ERα which is essential for maintenance of the cervix, and downstream components like VEGF, which is known to activate angiogenesis. Effects of artemisinin on apoptosis of ME-180 cells were measured by flow cytometry, DAPI, and annexin V staining. Expression of genes and proteins related to cell proliferation and apoptosis was quantified both at the transcriptional and translational levels by semi-quantitative RT-PCR and western blot analysis, respectively. Our findings demonstrated that artemisinin significantly downregulated the expression of ERα and its downstream component, VEGF. Antiproliferative activity was also supported by decreased telomerase activity and reduced expression of hTR and hTERT subunits. Additionally, artemisinin reduced the expression of the HPV-39 viral E6 and E7 components. Artemisinin-induced apoptosis was confirmed by FACS, nuclear chromatin condensation, annexin V staining. Increased expression of p53 with concomitant decrease in expression of the p53 inhibitor Mdm2 further supported that artemisinin-induced apoptosis was p53-dependent. The results clearly indicate that artemisinin induces antiproliferative and proapoptotic effects in HPV-39-infected ME-180 cells, and warrants further trial as an effective anticancer drug.
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Affiliation(s)
- Anushree Mondal
- Cancer Research Laboratory, Department of Zoology, University of Calcutta, Kolkata, India
| | - Urmi Chatterji
- Cancer Research Laboratory, Department of Zoology, University of Calcutta, Kolkata, India.,Centre for Research in Nanoscience and Nanotechnology, University of Calcutta, Kolkata, India
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Gurung RL, Lim SN, Low GKM, Hande MP. MST-312 Alters Telomere Dynamics, Gene Expression Profiles and Growth in Human Breast Cancer Cells. JOURNAL OF NUTRIGENETICS AND NUTRIGENOMICS 2015; 7:283-98. [PMID: 26022559 DOI: 10.1159/000381346] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND Targeting telomerase is a potential cancer management strategy given that it allows unlimited cellular replication in the majority of cancers. Dysfunctional telomeres are recognized as double-strand breaks. However, the status of DNA repair response pathways following telomerase inhibition is not well understood in human breast cancer cells. Here, we evaluated the effects of MST-312, a chemically modified derivative from tea catechin, epigallocatechin gallate, on telomere dynamics and DNA damage gene expression in breast cancer cells. METHODOLOGY Breast cancer cells MCF-7 and MDA-MB-231 were treated with MST-312, and telomere-telomerase homeostasis, induced DNA damage and gene expression profiling were analyzed. RESULTS MST-312 decreased telomerase activity and induced telomere dysfunction and growth arrest in breast cancer cells with more profound effects in MDA-MB-231 than in MCF-7 cells. Consistent with these data, the telomere-protective protein TRF2 was downregulated in MDA-MB-231 cells. MST-312 induced DNA damage at telomeres accompanied by reduced expression of DNA damage-related genes ATM and RAD50. Co-treatment with MST-312 and the poly(ADP-ribose) polymerase 1 (PARP-1) inhibitor PJ-34 further enhanced growth reduction as compared to single treatment with MST-312 or PJ-34. CONCLUSIONS Our work demonstrates potential importance for the establishment of antitelomerase cancer therapy using MST-312 along with PARP-1 inhibition in breast cancer therapy.
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Affiliation(s)
- Resham Lal Gurung
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
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10
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Ramakrishnan SK, Varshney A, Sharma A, Das BC, Yadava PK. Expression of targeted ribozyme against telomerase RNA causes altered expression of several other genes in tumor cells. Tumour Biol 2014; 35:5539-50. [PMID: 24664581 DOI: 10.1007/s13277-014-1729-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Accepted: 02/04/2014] [Indexed: 01/11/2023] Open
Abstract
Telomeres are tandem repeat sequences present at chromosome end that are synthesized by RNA-protein enzyme called telomerase. The RNA component (TR) serves as template for telomerase reverse transcriptase (TERT) for generating telomere repeats. TERT is overexpressed in actively dividing cells including cancerous cells, absent in differentiated somatic cells whereas human telomerase RNA (hTR) is present in normal as well as in cancer cells. Telomerase overexpression in cancer cells ensures telomere length maintenance that actually provides proliferative advantage to cells. Stable expression of ribozyme against hTR in HeLa cells results in reduction of hTR levels, telomerase activity, and telomere length which is accompanied by altered cell morphology and expression of several specific cellular genes. The altered genes deduced from differentially display PCR and 2D gel electrophoresis upon hTR knockdown have function in ribosome biogenesis, chromatin modulation, cell cycle control, and p63-dependant pathways. Our observations shows hTR participates in diverse cellular functions other than telomere maintenance, validates as a possible drug targets in p53- and pRB-negative status, and indicated possible cross-talks between telomerase and other cellular pathways.
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Affiliation(s)
- Suresh Kumar Ramakrishnan
- Applied Molecular Biology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India
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11
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Sekaran V, Soares J, Jarstfer MB. Telomere Maintenance as a Target for Drug Discovery. J Med Chem 2013; 57:521-38. [DOI: 10.1021/jm400528t] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Vijay Sekaran
- Division of Chemical Biology
and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Joana Soares
- Division of Chemical Biology
and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Michael B. Jarstfer
- Division of Chemical Biology
and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
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12
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Guittat L, Alberti P, Gomez D, De Cian A, Pennarun G, Lemarteleur T, Belmokhtar C, Paterski R, Morjani H, Trentesaux C, Mandine E, Boussin F, Mailliet P, Lacroix L, Riou JF, Mergny JL. Targeting human telomerase for cancer therapeutics. Cytotechnology 2011; 45:75-90. [PMID: 19003245 DOI: 10.1007/s10616-004-5127-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2004] [Accepted: 09/21/2004] [Indexed: 01/28/2023] Open
Abstract
The enzyme telomerase is involved in the replication of telomeres, specialized structures that cap and protect the ends of chromosomes. Its activity is required for maintenance of telomeres and for unlimited lifespan, a hallmark of cancer cells. Telomerase is overexpressed in the vast majority of human cancer cells and therefore represents an attractive target for therapy. Several approaches have been developed to inhibit this enzyme through the targeting of its RNA or catalytic components as well as its DNA substrate, the single-stranded 3'-telomeric overhang. Telomerase inhibitors are chemically diverse and include modified oligonucleotides as well as small diffusable molecules, both natural and synthetic. This review presents an update of recent investigations pertaining to these agents and discusses their biological properties in the context of the initial paradigm that the exposure of cancer cells to these agents should lead to progressive telomere shortening followed by a delayed growth arrest response.
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Affiliation(s)
- Lionel Guittat
- Laboratoire de Biophysique, Muséum National d'Histoire Naturelle USM503, INSERM U 565, CNRS UMR 5153, 43, rue Cuvier, 75231, Paris cedex 05, France
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13
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Büchner N, Altschmied J, Jakob S, Saretzki G, Haendeler J. Well-known signaling proteins exert new functions in the nucleus and mitochondria. Antioxid Redox Signal 2010; 13:551-8. [PMID: 19958149 DOI: 10.1089/ars.2009.2994] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
One distinguishing feature of eukaryotic cells is their compartmentalization into organelles, which all have a unique structural and functional identity. Some proteins are exclusively localized in a single organelle, whereas others are found in more than one. A few proteins, whose function was thought to be completely understood, were only recently found to be present in the mitochondria. Although these proteins come from diverse functional classes, their common new denominator is the regulation of respiratory chain activity. Therefore, this review focuses on new functions of the Signal Transducer and Activator of Transcription 3, originally described as a transcription factor, the most prominent Src kinase family members, Src, Fyn, and Yes, which were so far known as plasma membrane-associated molecular effectors of a variety of extracellular stimuli, the tyrosine phosphatase Shp-2 previously characterized as a modulator of cytosolic signal transduction involved in cell growth, development, inflammation, and chemotaxis, and Telomerase Reverse Transcriptase, the key enzyme preventing telomere erosion in the nucleus. Their unexpected localization in other organelles and regulation of mitochondrial and/or nuclear functions by them adds a new layer of regulatory complexity. This extends the flexibility to cope with changing environmental demands using a limited number of genes and proteins.
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Affiliation(s)
- Nicole Büchner
- Leibniz-Institute for Molecular Preventive Medicine, University of Duesseldorf , Duesseldorf, Germany
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14
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Abstract
Telomeres and telomerase play essential roles in the regulation of the lifespan of human cells. While normal human somatic cells do not or only transiently express telomerase and therefore shorten their telomeres with each cell division, most human cancer cells typically express high levels of telomerase and show unlimited cell proliferation. High telomerase expression allows cells to proliferate and expand long-term and therefore supports tumor growth. Owing to the high expression and its role, telomerase has become an attractive diagnostic and therapeutic cancer target. Imetelstat (GRN163L) is a potent and specific telomerase inhibitor and so far the only drug of its class in clinical trials. Here, we report on the structure and the mechanism of action of imetelstat as well as about the preclinical and clinical data and future prospects using imetelstat in cancer therapy.
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15
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Noreen F, Heinrich J, Moelling K. Antitumor activity of small double-stranded oligodeoxynucleotides targeting telomerase RNA in malignant melanoma cells. Oligonucleotides 2009; 19:169-78. [PMID: 19441892 DOI: 10.1089/oli.2008.0170] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Human telomerase RNA (hTR) is an intrinsic component of telomerase enzyme. Small interfering RNAs (siRNAs) and single-stranded antisense oligonucleotides have been used previously for silencing of the hTR. The objective of this study was to investigate the effect of partially double-stranded oligodeoxynucleotides (ODNs), in vitro and in vivo in comparison to single-stranded antisense ODNs and siRNAs. ODNs were designed on the basis of structural properties of an ODN from previous studies on HIV, to target the hTR in the human cervical carcinoma HeLa cell line and mouse telomerase RNA (mTR) in the murine metastatic melanoma B16-F10 cell line, respectively. Our results indicate that ODNs were able to inhibit the hTR by 68% and the mTR by 81% in the respective cell lines. This correlated with ODN-mediated rapid inhibition of cell proliferation and induction of apoptosis excluding slow effects on telomerase function. The inhibition of the hTR was decreased by knock-down of the cellular RNases H suggesting their contribution. Furthermore, we showed a reduction in numbers of metastases by 70% after intravenous administration of ODN-transfected B16-F10 cells in C57BL/6 mice. Our study demonstrates the potential utility of these hairpin-loop-structured ODNs as a different group of nucleic acids for telomerase-based antiproliferative strategies.
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Affiliation(s)
- Faiza Noreen
- Institute of Medical Virology, University of Zurich, Zurich, Switzerland
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16
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Shammas MA, Qazi A, Batchu RB, Bertheau RC, Wong JYY, Rao MY, Prasad M, Chanda D, Ponnazhagan S, Anderson KC, Steffes CP, Munshi NC, De Vivo I, Beer DG, Gryaznov S, Weaver DW, Goyal RK. Telomere maintenance in laser capture microdissection-purified Barrett's adenocarcinoma cells and effect of telomerase inhibition in vivo. Clin Cancer Res 2008; 14:4971-80. [PMID: 18676772 DOI: 10.1158/1078-0432.ccr-08-0473] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
PURPOSE The aims of this study were to investigate telomere function in normal and Barrett's esophageal adenocarcinoma (BEAC) cells purified by laser capture microdissection and to evaluate the effect of telomerase inhibition in cancer cells in vitro and in vivo. EXPERIMENTAL DESIGN Epithelial cells were purified from surgically resected esophagi. Telomerase activity was measured by modified telomeric repeat amplification protocol and telomere length was determined by real-time PCR assay. To evaluate the effect of telomerase inhibition, adenocarcinoma cell lines were continuously treated with a specific telomerase inhibitor (GRN163L) and live cell number was determined weekly. Apoptosis was evaluated by Annexin labeling and senescence by beta-galactosidase staining. For in vivo studies, severe combined immunodeficient mice were s.c. inoculated with adenocarcinoma cells and following appearance of palpable tumors, injected i.p. with saline or GRN163L. RESULTS Telomerase activity was significantly elevated whereas telomeres were shorter in BEAC cells relative to normal esophageal epithelial cells. The treatment of adenocarcinoma cells with telomerase inhibitor, GRN163L, led to loss of telomerase activity, reduction in telomere length, and growth arrest through induction of both the senescence and apoptosis. GRN163L-induced cell death could also be expedited by addition of the chemotherapeutic agents doxorubicin and ritonavir. Finally, the treatment with GRN163L led to a significant reduction in tumor volume in a subcutaneous tumor model. CONCLUSIONS We show that telomerase activity is significantly elevated whereas telomeres are shorter in BEAC and suppression of telomerase inhibits proliferation of adenocarcinoma cells both in vitro and in vivo.
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Affiliation(s)
- Masood A Shammas
- Department of Surgery, Wayne State University and Karmanos Cancer Institute, Detroit, Michigan 48201, USA
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Abstract
Human telomerase, the reverse transcriptase which extends the life span of a cell by adding telomeric repeats to chromosome ends, is expressed in most cancer cells but not in the majority of normal somatic cells. Inhibition of telomerase therefore holds great promise as anticancer therapy. We have synthesized a novel telomerase inhibitor GRN163L, a lipid-attached phosphoramidate oligonucleotide complementary to template region of the RNA subunit of telomerase. Here, we report that GRN163L is efficiently taken up by human myeloma cells without any need of transfection and is resistant to nucleolytic degradation. The exposure of myeloma cells to GRN163L led to an effective inhibition of telomerase activity, reduction of telomere length and apoptotic cell death after a lag period of 2-3 weeks. Mismatch control oligonucleotides had no effect on growth of myeloma cells. The in vivo efficacy of GRN163L was confirmed in two murine models of human multiple myeloma. In three independent experiments, significant reduction in tumor cell growth and better survival than control mice was observed. Furthermore, GRN163L-induced myeloma cell death could be significantly enhanced by Hsp90 inhibitor 17AAG. These data provide the preclinical rationale for clinical evaluation of GRN163L in myeloma and in combination with 17AAG.
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18
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Phatak P, Burger AM. Telomerase and its potential for therapeutic intervention. Br J Pharmacol 2007; 152:1003-11. [PMID: 17603541 PMCID: PMC2095101 DOI: 10.1038/sj.bjp.0707374] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2007] [Revised: 06/08/2007] [Accepted: 06/08/2007] [Indexed: 01/12/2023] Open
Abstract
Telomerase and telomeres are attractive targets for anticancer therapy. This is supported by the fact that the majority of human cancers express the enzyme telomerase which is essential to maintain their telomere length and thus, to ensure indefinite cell proliferation--a hallmark of cancer. Tumours have relatively shorter telomeres compared to normal cell types, opening the possibility that human cancers may be considerably more susceptible to killing by agents that inhibit telomere replication than normal cells. Advances in the understanding of the regulation of telomerase activity and the telomere structure, as well as the identification of telomerase and telomere associated binding proteins have opened new avenues for therapeutic intervention. Here, we review telomere and telomerase biology and the various approaches which have been developed to inhibit the telomere/telomerase complex over the past decade. They include inhibitors of the enzyme catalytic subunit and RNA component, agents that target telomeres, telomerase vaccines and drugs targeting binding proteins. The emerging role of telomerase in cancer stem cells and the implications for cancer therapy are also discussed.
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Affiliation(s)
- P Phatak
- Department of Pharmacology and Experimental Therapeutics; and Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine Baltimore, MD, USA
| | - A M Burger
- Department of Pharmacology and Experimental Therapeutics; and Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine Baltimore, MD, USA
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Kondo Y, Kondo S. Telomerase RNA inhibition using antisense oligonucleotide against human telomerase RNA linked to a 2',5'-oligoadenylate. Methods Mol Biol 2007; 405:97-112. [PMID: 18369820 DOI: 10.1007/978-1-60327-070-0_9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Telomerase, a ribonucleoprotein enzyme, is detected in the vast majority of cancers, including malignant gliomas, but not in most normal somatic cells. To inhibit telomerase function effectively, we have adopted the 2',5'-oligoadenylate (2-5A) antisense system. 2-5A is a mediator of one pathway of interferon actions by activating RNase L, resulting in single-stranded RNA cleavage. By linking 2-5A to an antisense oligonucleotide, RNase L degrades the targeted RNA specifically and effectively. Therefore, we have synthesized the antisense oligonucleotide against human telomerase RNA component (hTR) linked to 2-5A (2-5A-anti-hTR) and have demonstrated its antitumor effect on telomerase-positive cancer cells in vitro and in vivo.
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Affiliation(s)
- Yasuko Kondo
- Department of Neurosurgery, Anderson Cancer Center, Houston, TX, USA
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20
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Hosseini-Asl S, Atri M, Modarressi MH, Salhab M, Mokbel K, Mehdipour P. The expression of hTR and hTERT in human breast cancer: correlation with clinico-pathological parameters. INTERNATIONAL SEMINARS IN SURGICAL ONCOLOGY : ISSO 2006; 3:20. [PMID: 16925810 PMCID: PMC1564405 DOI: 10.1186/1477-7800-3-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/17/2006] [Accepted: 08/22/2006] [Indexed: 02/08/2023]
Abstract
BACKGROUND Telomerase is a ribonucleoprotein enzyme that synthesizes telomeres after cell division and maintains chromosomal stability leading to cellular immortalization. Telomerase has been associated with negative prognostic indicators in some studies. The present study aims to detect any association between telomerase sub-units: hTERT and hTR and the prognostic indicators including tumour's size and grade, nodal status and patient's age. METHODS Tumour samples from 46 patients with primary invasive breast cancer and 3 patients with benign tumours were collected. RT-PCR analysis was used for the detection of hTR, hTERT, and PGM1 (as a housekeeping) genes expression. RESULTS The expression of hTR and hTERT was found in 31(67.4%) and 38 (82.6%) samples respectively. We observed a significant association between hTR gene expression and younger age at diagnosis (p = 0.019) when comparing patients < or = 40 years with those who are older than 40 years. None of the benign tumours expressed hTR gene. However, the expression of hTERT gene was revealed in 2 samples. No significant association between hTR and hTERT expression and tumour's grade, stage and nodal status was seen. CONCLUSION The expression of hTR and hTERT seems to be independent of tumour's stage. hTR expression probably plays a greater role in mammary tumourogenesis in younger women (< or = 40 years) and this may have therapeutic implications in the context of hTR targeting strategies.
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Affiliation(s)
- Saied Hosseini-Asl
- Department of Medical Genetics, School of Medicine, Tehran University of Medical Sciences, Tehran, IR, Iran
| | - Morteza Atri
- Cancer Institute, Tehran University of Medical Sciences/Day General Hospital, Tehran, IR, Iran
| | - Mohammad H Modarressi
- Department of Medical Genetics, School of Medicine, Tehran University of Medical Sciences, Tehran, IR, Iran
| | | | | | - Parvin Mehdipour
- Department of Medical Genetics, School of Medicine, Tehran University of Medical Sciences, Tehran, IR, Iran
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21
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Effect of an epoxy derivative of 2′5′-trioligoadenylate on human neuroblastoma cells. NEUROPHYSIOLOGY+ 2006. [DOI: 10.1007/s11062-006-0029-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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22
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Liu T, Hu B, Chung MJ, Ullenbruch M, Jin H, Phan SH. Telomerase regulation of myofibroblast differentiation. Am J Respir Cell Mol Biol 2006; 34:625-33. [PMID: 16424384 PMCID: PMC2644224 DOI: 10.1165/rcmb.2005-0252oc] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Telomerase activity, which has wide expression in cancerous cells, is induced in lung proliferating fibroblasts. It is preferentially expressed in fibroblasts versus myofibroblasts. It is unknown whether regulation of telomerase expression is related to the process of fibroblast differentiation into myofibroblasts. The objective of this study was to clarify such a potential link between telomerase expression and myofibroblast differentiation. Telomerase inhibitor, 3'-azido-2',3'-dideoxythymidine, or antisense oligonucleotide to the telomerase RNA component was used to inhibit the induced fibroblast telomerase activity. The results showed that inhibition of induced telomerase increased alpha-smooth muscle actin expression, an indicator of myofibroblast differentiation. In contrast, induction of telomerase by basic fibroblast growth factor inhibited alpha-smooth muscle actin expression. These findings suggest that the loss of telomerase activity is closely associated with myofibroblast differentiation and possibly functions as a trigger for myofibroblast differentiation. Conversely, expression of telomerase suppresses myofibroblast differentiation.
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Affiliation(s)
- Tianju Liu
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
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23
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Abstract
Telomeres are complex structures which serve to protect chromosome ends. Telomere shortening occurs in normal somatic cells reaching a point in which cells senesce. Senescence can be counteracted by activating telomerase. Telomerase activity is present in a majority of cancer cells and requires the upregulation of the reverse transcriptase component called hTERT. Because telomerase activity is essential for proliferation of most cancer cells, therapeutic strategies have been developed to inhibit its activity. These strategies centre on targeting the active site, hTERT and hTERC expression, core enzyme stability and telomeric DNA. Successful approaches involve a combination of traditional drugs with telomerase inhibitors. Disrupting the functional expression of hTERT is particularly effective in agreement with evidence that hTERT is an antiapoptotic factor in some cancer cells. In addition, approaches that stabilise DNA secondary structures may disrupt telomere maintenance through a variety of routes making them, potentially, very potent in attack-ing cancer cells.
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Affiliation(s)
- Terace M Fletcher
- Department of Biochemistry and Molecular Biology, University of Miami School of Medicine, 1011 NW 15 Street, Miami, FL 33136, USA.
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24
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Ye J, Wu YL, Zhang S, Chen Z, Guo LX, Zhou RY, Xie H. Inhibitory effect of human telomerase antisense oligodeoxyribonucleotides on the growth of gastric cancer cell lines in variant tumor pathological subtype. World J Gastroenterol 2005; 11:2230-7. [PMID: 15818731 PMCID: PMC4305804 DOI: 10.3748/wjg.v11.i15.2230] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To investigate the inhibitory effect of specialized human telomerase antisense oligodeoxyribonucleotides on the growth of well (MKN-28), moderately (SGC-7901) and poorly (MKN-45) differentiated gastric cancer cell lines under specific conditions and its inhibition mechanism, and to observe the correlation between the growth inhibition ratio and the tumor pathologic subtype of gastric cancer cells.
METHODS: Telomerase activity in three gastric cancer cell lines of variant tumor pathologic subtype was determined by modified TRAP assay before and after the specialized human telomerase antisense oligodeoxyribonucleotides were dealt with under specific conditions. Effect of antisense oligomer under specific conditions of the growth and viability of gastric cancer cell lines was explored by using trypan blue dye exclusion assay, and cell apoptosis was detected by cell morphology observation, flow cytometry and TUNEL assay.
RESULTS: Telomerase activity was detected in well, moderately and poorly differentiated gastric cancer cell lines (the quantification expression of telomerase activity was 43.7TPG, 56.5TPG, 76.7TPG, respectively).Telomerase activity was controlled to 30.2TPG, 36.3TPG and 35.2TPG for MKN-28, SGC-7901 and MKN-45 cell lines respectively after treatment with human telomerase antisense oligomers at the concentration of 5 μmol/L, and was entirely inhibited at 10 μmol/L, against the template region of telomerase RNA component, whereas no inhibition effect was detected in missense oligomers (P<0.05). After treatment with antisense oligomers at different concentrations under specific conditions for 96 h, significant growth inhibition effects were found in MKN-45 and SGC-7901 gastric cancer cell lines (the inhibition ratio was 40.89% and 71.28%), but not in MKN-28 cell lines (15.86%). The ratio of inactive SGC-7901 cells increased according to the prolongation of treatment from 48 to 96 h. Missense oligomers could not lead to the same effect (P<0.05). Apoptosis of SGC-7901 and MKN-45 cells was detected not only by morphology and TUNEL assay but also by flow cytometry. The apoptotic rate reached 33.56% for SGC-7901 cells and 44.75% for MKN-45 cells.
CONCLUSION: The viability and proliferation of gastric cancer cells can be inhibited by antisense telomerase oligomers. The growth inhibition of gastric cancer cells is correlated with concentration, time and sequence specialty of antisense oligomers. The inhibition mechanism of antisense human telomerase oligomers depends not only on the sequence specialty but also on the biological characteristics of gastric cancer cell lines.
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Affiliation(s)
- Jing Ye
- Department of Gastroenterology, Ruijin Hospital, Shanghai Second Medical University, Shanghai 200025, China
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25
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Abstract
Telomeres are specialized high-order chromatin structures that cap the ends of eukaryotic chromosomes. In vertebrates, telomeric DNA is composed of repetitions of the TTAGGG hexanucleotide, is bound to a set of specific proteins, and is elongated by the reverse transcriptase enzyme telomerase. Telomerase activity is promptly detected in cells with an indefinite replicative potential, such as cancer cells, while is almost undetectable in normal cells, which are characterized by a limited life span. Mounting evidence indicates that the maintenance of telomere integrity and telomerase protect cells from apoptosis. Disruption of the telomere capping function and (or) telomerase inhibition elicit an apoptotic response in cancer cells, while restoration of telomerase activity in somatic cells confers resistance to apoptosis. The possible mechanisms linking telomeres, telomerase and apoptosis are discussed in this review, together with the impact of this field in anticancer research.
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26
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Abstract
Telomeres, located at the ends of eukaryotic chromosomes, are synthesized by the enzyme telomerase and are responsible for maintaining chromosome length. The absence of telomerase in most somatic cells has been associated with telomere shortening and aging of these cells. In contrast, high levels of telomerase activity are observed in over 90% of human cancer cells. The absence of telomerase in normal and aging cells is considered a natural defense against development of cancer. However, we do not know what triggers the reappearance of telomerase in cancer cells. Telomerase activity is directly correlated with the expression of its active catalytic component, the human telomerase reverse transcriptase (hTERT), which is believed to be controlled primarily at the level of transcription. Elucidation of the control of telomerase in aging and in cancer as an age-related disease has considerable potential in leading to novel approaches in anti-aging medicine.
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Affiliation(s)
- Ali Ahmed
- University of Alabama at Birmingham, Birmingham, Alabama 35294, USA.
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27
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Shammas MA, Koley H, Beer DG, Li C, Goyal RK, Munshi NC. Growth arrest, apoptosis, and telomere shortening of Barrett's-associated adenocarcinoma cells by a telomerase inhibitor. Gastroenterology 2004; 126:1337-46. [PMID: 15131795 DOI: 10.1053/j.gastro.2004.01.026] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
BACKGROUND & AIMS Barrett's esophageal adenocarcinoma (BEAC) is a complication of gastroesophageal reflux disease, with no effective chemotherapy and poor prognosis. BEAC cells, like many other types of cancers, may reactivate telomerase to achieve unlimited proliferative potential, making telomerase a unique therapeutic target. The purpose of this study was to evaluate effects of telomerase inhibition on BEAC. METHODS We examined the effect of a selective G-quadruplex intercalating telomerase inhibitor, 2,6-bis[3-(N-Piperidino)propionamido]anthracene-9,10-dione (PPA), on telomerase activity, telomere length, colony size distribution, and proliferative potential in 2 BEAC cell lines, BIC-1 and SEG-1. RESULTS Telomerase activity was >10-fold and >600-fold elevated in the adenocarcinoma cells as compared with normal gastric/intestinal cells and normal diploid fibroblasts, respectively. Telomeres were short, being less than 4 kilobase pair in both tumor cell lines. Exposure to PPA effectively inhibited telomerase activity and shortened telomeres. PPA also arrested cell proliferation and reduced colony number and size after a lag period of about 10 cell generations, consistent with the attrition of telomeres. The growth arrest was not due to senescence but was due to apoptosis. Expression analysis of the cells following PPA treatment did not show significant change in the expression of genes involved in cell-cycle proliferation and apoptosis. Exposure to PPA had no effect on proliferative potential of normal intestinal cells. CONCLUSIONS We conclude that telomerase inhibition by PPA induces cell growth arrest in BEAC cells and demonstrate the potential of telomerase inhibitors in chemoprevention and treatment of Barrett's-associated esophageal adenocarcinoma.
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Das S, El-Deiry WS, Somasundaram K. Efficient growth inhibition of HPV 16 E6-expressing cells by an adenovirus-expressing p53 homologue p73β. Oncogene 2003; 22:8394-402. [PMID: 14627980 DOI: 10.1038/sj.onc.1206908] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Tumor suppressor p53 functions are downregulated in most cervical cancers, because the product of human papilloma virus (HPV) oncogene E6 binds to and inactivates p53 by promoting its degradation. p73, a p53 homologue, is similar to p53 in structure and function but yet not degraded by HPV E6 gene product. In this study, we have developed a replication-deficient recombinant adenovirus, which expresses p73beta (Ad-p73). Infection of human cancer cells with Ad-p73 results in several fold increase of p73beta levels as well as its known target genes like p21(WAF1/CIP1). Ad-p73-infected cells showed reduced cellular DNA synthesis, arrest in G1 phase of cell cycle and induction of apoptosis. Ad-p73 inhibited the growth of cancer cells of different types. More importantly, Ad-p73 inhibited the growth of cell lines carrying HPV E6 gene, which was introduced by stable integration, more efficiently in comparison to an Ad-p53. Furthermore, Ad-p73 also inhibited the growth of HeLa cells, a cell line derived from cervical cancer, very efficiently. The ability of Ad-p73 to inhibit the growth of HPV E6-expressing cells and HeLa cells correlated with the stable expression of functional p73 in the presence of E6. These results suggest that Ad-p73 could be used as a potential gene therapy agent against cervical cancer.
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Affiliation(s)
- Sanjeev Das
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560 012, India
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29
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Abstract
A number of different approaches have been developed to inhibit telomerase activity in human cancer cells. Different components and types of inhibitors targeting various regulatory levels have been regarded as useful for telomerase inhibition. Most methods, however, rely on successive telomere shortening. This process is very slow and causes a long time lag between the onset of inhibition and the occurrence of senescence or apoptosis as a reversal of the immortal phenotype. Many telomerase inhibitors seem to be most efficient when combined with conventional chemotherapeutics. There are some promising approaches that seem to circumvent the slow way of telomere shortening and induce fast apoptosis in treated tumor cells. It has been demonstrated that telomerase may be involved in triggering apoptosis, but the underlying molecular mechanism remains unclear.
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30
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Abstract
The unique biology of telomeres and telomerase plays important roles in many aspects of mammalian cell physiology. Over the past decade, several lines of evidence have confirmed that the maintenance of telomeres and telomerase participate actively in the pathogenesis of human cancer. Specifically, activation of telomerase is strongly associated with cancer, and recent observations confirm that telomeres and telomerase perform important roles in both suppressing and facilitating malignant transformation by regulating genomic stability and cell lifespan. In addition, recent evidence suggests that telomerase activation contributes to tumorigenesis independently of its role in maintaining telomere length. Here we review recent developments in our understanding of the relationships among telomeres, telomerase, and cancer.
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Affiliation(s)
- Kenkichi Masutomi
- Department of Medical Oncology, Dana-Farber Cancer Institute, 44 Binney Street, Dana 710C, Boston, MA 02115, USA
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Ma CH, Sun WS, Tian PK, Gao LF, Liu SX, Wang XY, Zhang LN, Cao YL, Han LH, Liang XH. A novel HBV antisense RNA gene delivery system targeting hepatocellular carcinoma. World J Gastroenterol 2003; 9:463-7. [PMID: 12632498 PMCID: PMC4621562 DOI: 10.3748/wjg.v9.i3.463] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2002] [Revised: 08/23/2002] [Accepted: 09/04/2002] [Indexed: 02/06/2023] Open
Abstract
AIM To construct a novel HBV antisense RNA delivery system targeting hapatocellular carcinoma and study its inhibitory effect in vitro and in vivo. METHODS GE7,a 16-peptide specific to EGFR, and HA20,a homologue of N-terminus of haemagglutinin of influenza viral envelope protein, were synthesized and conjugated with polylysin. The above conjugates were organized into the pEBAF-as-preS2, a hepatocarcinoma specific HBV antisense expression vector, to construct a novel HBV antisense RNA delivery system, named AFP-enhancing 4-element complex. Hepatocelluar carcinoma HepG2.2.15 cells was used to assay the in vitro inhibition of the complex on HBV. Expression of HBV antigen was assayed by ELISA. BALB/c nude mice bearing HepG2.2.15 cells were injected with AFP-enhancing 4-element complex. The expression of HBV antisense RNA was examined by RT-PCR and the size of tumor in nude mice were measured. RESULTS The AFP-enhancing 4-element complex was constructed and DNA was completely trapped at the slot with no DNA migration when the ratio of polypeptide to plasmid was 1:1. The expression of HBsAg and HBeAg of HepG2.2.15 cells was greatly decreased after being transfected by AFP-enhancing 4-element complex. The inhibitory rates were 33.4 % and 58.5 % respectively. RT-PCR showed HBV antisense RNA expressed specifically in liver tumor cells of tumor-bearing nude mice. After 4 injections of AFP-enhancing 4-element complex containing 0.2 micro g DNA, the diameter of the tumor was 0.995 cm+/-0.35, which was significantly smaller than that of the control groups(2.215 cm+/-0.25, P<0.05). CONCLUSION AFP-enhancing 4-element complex could deliver HBV antisense RNA targeting on hepatocarcinoma and inhibit both HBV and liver tumor cells in vitro and in vivo.
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Affiliation(s)
- Chun-Hong Ma
- Institute of Immunology,Medical College of Shandong University, Jinan 250012, Shandong Province, China
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