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Razgonova MP, Zakharenko AM, Golokhvast KS, Thanasoula M, Sarandi E, Nikolouzakis K, Fragkiadaki P, Tsoukalas D, Spandidos DA, Tsatsakis A. Telomerase and telomeres in aging theory and chronographic aging theory (Review). Mol Med Rep 2020; 22:1679-1694. [PMID: 32705188 PMCID: PMC7411297 DOI: 10.3892/mmr.2020.11274] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 06/24/2020] [Indexed: 01/03/2023] Open
Abstract
The current review focuses on the connection of telomerase and telomeres with aging. In this review, we describe the changes in telomerase and telomere length (TEL) during development, their role in carcinogenesis processes, and the consequences of reduced telomerase activity. More specifically, the connection of TEL in peripheral blood cells with the development of aging‑associated diseases is discussed. The review provides systematic data on the role of telomerase in mitochondria, the biology of telomeres in stem cells, as well as the consequences of the forced expression of telomerase (telomerization) in human cells. Additionally, it presents the effects of chronic stress exposure on telomerase activity, the effect of TEL on fertility, and the effect of nutraceutical supplements on TEL. Finally, a comparative review of the chronographic theory of aging, presented by Olovnikov is provided based on currently available scientific research on telomere, telomerase activity, and the nature of aging by multicellular organisms.
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Affiliation(s)
- Mayya P. Razgonova
- N.I. Vavilov All-Russian Institute of Plant Genetic Resources, 190000 Saint-Petersburg, Russia
- Far Eastern Federal University, 690950 Vladivostok, Russia
| | - Alexander M. Zakharenko
- N.I. Vavilov All-Russian Institute of Plant Genetic Resources, 190000 Saint-Petersburg, Russia
- Far Eastern Federal University, 690950 Vladivostok, Russia
| | - Kirill S. Golokhvast
- N.I. Vavilov All-Russian Institute of Plant Genetic Resources, 190000 Saint-Petersburg, Russia
- Far Eastern Federal University, 690950 Vladivostok, Russia
- Pacific Geographical Institute, Far Eastern Branch of The Russian Academy of Sciences, 690041 Vladivostok, Russia
| | - Maria Thanasoula
- Metabolomic Μedicine, Health Clinics for Autoimmune and Chronic Diseases, 10674 Athens, Greece
| | - Evangelia Sarandi
- Metabolomic Μedicine, Health Clinics for Autoimmune and Chronic Diseases, 10674 Athens, Greece
| | | | - Persefoni Fragkiadaki
- Laboratory of Toxicology, Medical School, University of Crete, 71003 Heraklion, Greece
- Spin-Off Toxplus S.A., 71601 Heraklion, Greece
| | - Dimitris Tsoukalas
- Metabolomic Μedicine, Health Clinics for Autoimmune and Chronic Diseases, 10674 Athens, Greece
| | - Demetrios A. Spandidos
- Laboratory of Clinical Virology, School of Medicine, University of Crete, Heraklion 71003, Greece
| | - Aristidis Tsatsakis
- Laboratory of Toxicology, Medical School, University of Crete, 71003 Heraklion, Greece
- Spin-Off Toxplus S.A., 71601 Heraklion, Greece
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Serakinci N, Mega Tiber P, Orun O. Chromatin modifications of hTERT gene in hTERT-immortalized human mesenchymal stem cells upon exposure to radiation. Eur J Med Genet 2018; 61:288-293. [DOI: 10.1016/j.ejmg.2017.12.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 12/14/2017] [Accepted: 12/23/2017] [Indexed: 01/24/2023]
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Pompili L, Leonetti C, Biroccio A, Salvati E. Diagnosis and treatment of ALT tumors: is Trabectedin a new therapeutic option? JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2017; 36:189. [PMID: 29273061 PMCID: PMC5741932 DOI: 10.1186/s13046-017-0657-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Accepted: 12/01/2017] [Indexed: 12/22/2022]
Abstract
Telomeres are specialized nucleoprotein structures responsible for protecting chromosome ends in order to prevent the loss of genomic information. Telomere maintenance is required for achieving immortality by neoplastic cells. While most cancer cells rely on telomerase re-activation for linear chromosome maintenance and sustained proliferation, a significant population of cancers (10-15%) employs telomerase-independent strategies, collectively referred to as Alternative Lengthening of Telomeres (ALT). ALT mechanisms involve different types of homology-directed telomere recombination and synthesis. These processes are facilitated by loss of the ATRX or DAXX chromatin-remodeling factors and by abnormalities of the telomere nucleoprotein architecture. Although the functional consequences of telomerase and ALT up-regulation are similar in that they both prevent overall telomere shortening in tumors, these telomere maintenance mechanisms (TMMs) differ in several aspects which may account for their differential prognostic significance and response to therapy in various tumor types. Therefore, reliable methods for detecting telomerase activity and ALT are likely to become an important pre-requisite for the use of treatments targeting one or other of these mechanisms. However, the question whether ALT presence can confer sensitivity to rationally designed anti-cancer therapies is still open. Here we review the latest discoveries in terms of mechanisms of ALT activation and maintenance in human tumors, methods for ALT identification in cell lines and human tissues and biomarkers validation. Then, original results on sensitivity to rational based pre-clinical and clinical anti-tumor drugs in ALT vs hTERT positive cells will be presented.
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Affiliation(s)
- Luca Pompili
- UOSD SAFU, Regina Elena National Cancer Institute, Rome, Italy.,University of Tuscia, Viterbo, Italy
| | - Carlo Leonetti
- UOSD SAFU, Regina Elena National Cancer Institute, Rome, Italy
| | - Annamaria Biroccio
- Oncogenomic and Epigenetic Unit, Regina Elena National Cancer Institute, Via Elio Chianesi, 53 -, 00144, Rome, Italy
| | - Erica Salvati
- Oncogenomic and Epigenetic Unit, Regina Elena National Cancer Institute, Via Elio Chianesi, 53 -, 00144, Rome, Italy.
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Zhang Y, Dakic A, Chen R, Dai Y, Schlegel R, Liu X. Direct HPV E6/Myc interactions induce histone modifications, Pol II phosphorylation, and hTERT promoter activation. Oncotarget 2017; 8:96323-96339. [PMID: 29221209 PMCID: PMC5707103 DOI: 10.18632/oncotarget.22036] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2017] [Accepted: 09/15/2017] [Indexed: 11/25/2022] Open
Abstract
Human Papillomavirus Viruses (HPVs) are associated with the majority of human cervical and anal cancers and 10-30% of head and neck squamous carcinomas. E6 oncoprotein from high risk HPVs interacts with the p53 tumor suppressor protein to facilitate its degradation and increases telomerase activity for extending the life span of host cells. We published previously that the Myc cellular transcription factor associates with the high-risk HPV E6 protein in vivo and participates in the transactivation of the hTERT promoter. In the present study, we further analyzed the role of E6 and the Myc-Max-Mad network in regulating the hTERT promoter. We confirmed that E6 and Myc interact independently and that Max can also form a complex with E6. However, the E6/Max complex is observed only in the presence of Myc, suggesting that E6 associates with Myc/Max dimers. Consistent with the hypothesis that Myc is required for E6 induction of the hTERT promoter, Myc antagonists (Mad or Mnt) significantly blocked E6-mediated transactivation of the hTERT promoter. Analysis of Myc mutants demonstrated that both the transactivation domain and HLH domain of Myc protein were required for binding E6 and for the consequent transactivation of the hTERT promoter, by either Myc or E6. We also showed that E6 increased phosphorylation of Pol II on the hTERT promoter and induced epigenetic histone modifications of the hTERT promoter. More important, knockdown of Myc expression dramatically decreased engagement of acetyl-histones and Pol II at the hTERT promoter in E6-expressing cells. Thus, E6/Myc interaction triggers the transactivation of the hTERT promoter by modulating both histone modifications, Pol II phosphorylation and promoter engagement, suggesting a novel mechanism for telomerase activation and a new target for HPV- associated human cancer.
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Affiliation(s)
- Yiyu Zhang
- Department of Pathology, Center for Cell Reprogramming, Georgetown University Medical Center, Washington, DC 20057, USA
| | - Aleksandra Dakic
- Department of Pathology, Center for Cell Reprogramming, Georgetown University Medical Center, Washington, DC 20057, USA
| | - Renxiang Chen
- Department of Pathology, Center for Cell Reprogramming, Georgetown University Medical Center, Washington, DC 20057, USA
| | - Yuhai Dai
- Department of Pathology, Center for Cell Reprogramming, Georgetown University Medical Center, Washington, DC 20057, USA
| | - Richard Schlegel
- Department of Pathology, Center for Cell Reprogramming, Georgetown University Medical Center, Washington, DC 20057, USA
| | - Xuefeng Liu
- Department of Pathology, Center for Cell Reprogramming, Georgetown University Medical Center, Washington, DC 20057, USA
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Amorim JP, Santos G, Vinagre J, Soares P. The Role of ATRX in the Alternative Lengthening of Telomeres (ALT) Phenotype. Genes (Basel) 2016; 7:E66. [PMID: 27657132 PMCID: PMC5042396 DOI: 10.3390/genes7090066] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 09/07/2016] [Accepted: 09/12/2016] [Indexed: 12/15/2022] Open
Abstract
Telomeres are responsible for protecting chromosome ends in order to prevent the loss of coding DNA. Their maintenance is required for achieving immortality by neoplastic cells and can occur by upregulation of the telomerase enzyme or through a homologous recombination-associated process, the alternative lengthening of telomeres (ALT). The precise mechanisms that govern the activation of ALT or telomerase in tumor cells are not fully understood, although cellular origin may favor one of the other mechanisms that have been found thus far in mutual exclusivity. Specific mutational events influence ALT activation and maintenance: a unifying frequent feature of tumors that acquire this phenotype are the recurrent mutations of the Alpha Thalassemia/Mental Retardation Syndrome X-Linked (ATRX) or Death-Domain Associated Protein (DAXX) genes. This review summarizes the established criteria about this phenotype: its prevalence, theoretical molecular mechanisms and relation with ATRX, DAXX and other proteins (directly or indirectly interacting and resulting in the ALT phenotype).
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Affiliation(s)
- João P Amorim
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto 4200-135, Portugal.
- Instituto de Patologia e Imunologia Molecular da Universidade do Porto (Ipatimup), Porto 4200-135, Portugal.
- Instituto de Ciências Biomédicas Abel Salazar da Universidade do Porto, Porto 4050-313, Portugal.
| | - Gustavo Santos
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto 4200-135, Portugal.
- Instituto de Patologia e Imunologia Molecular da Universidade do Porto (Ipatimup), Porto 4200-135, Portugal.
- Instituto de Ciências Biomédicas Abel Salazar da Universidade do Porto, Porto 4050-313, Portugal.
| | - João Vinagre
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto 4200-135, Portugal.
- Instituto de Patologia e Imunologia Molecular da Universidade do Porto (Ipatimup), Porto 4200-135, Portugal.
- Instituto de Ciências Biomédicas Abel Salazar da Universidade do Porto, Porto 4050-313, Portugal.
| | - Paula Soares
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto 4200-135, Portugal.
- Instituto de Patologia e Imunologia Molecular da Universidade do Porto (Ipatimup), Porto 4200-135, Portugal.
- Instituto de Ciências Biomédicas Abel Salazar da Universidade do Porto, Porto 4050-313, Portugal.
- Departamento de Patologia e Oncologia, Faculdade de Medicina da Universidade do Porto, Porto 4200-139, Portugal.
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Jäger K, Walter M. Therapeutic Targeting of Telomerase. Genes (Basel) 2016; 7:genes7070039. [PMID: 27455328 PMCID: PMC4962009 DOI: 10.3390/genes7070039] [Citation(s) in RCA: 86] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2016] [Revised: 06/16/2016] [Accepted: 06/24/2016] [Indexed: 12/20/2022] Open
Abstract
Telomere length and cell function can be preserved by the human reverse transcriptase telomerase (hTERT), which synthesizes the new telomeric DNA from a RNA template, but is normally restricted to cells needing a high proliferative capacity, such as stem cells. Consequently, telomerase-based therapies to elongate short telomeres are developed, some of which have successfully reached the stage I in clinical trials. Telomerase is also permissive for tumorigenesis and 90% of all malignant tumors use telomerase to obtain immortality. Thus, reversal of telomerase upregulation in tumor cells is a potential strategy to treat cancer. Natural and small-molecule telomerase inhibitors, immunotherapeutic approaches, oligonucleotide inhibitors, and telomerase-directed gene therapy are useful treatment strategies. Telomerase is more widely expressed than any other tumor marker. The low expression in normal tissues, together with the longer telomeres in normal stem cells versus cancer cells, provides some degree of specificity with low risk of toxicity. However, long term telomerase inhibition may elicit negative effects in highly-proliferative cells which need telomerase for survival, and it may interfere with telomere-independent physiological functions. Moreover, only a few hTERT molecules are required to overcome senescence in cancer cells, and telomerase inhibition requires proliferating cells over a sufficient number of population doublings to induce tumor suppressive senescence. These limitations may explain the moderate success rates in many clinical studies. Despite extensive studies, only one vaccine and one telomerase antagonist are routinely used in clinical work. For complete eradication of all subpopulations of cancer cells a simultaneous targeting of several mechanisms will likely be needed. Possible technical improvements have been proposed including the development of more specific inhibitors, methods to increase the efficacy of vaccination methods, and personalized approaches. Telomerase activation and cell rejuvenation is successfully used in regenerative medicine for tissue engineering and reconstructive surgery. However, there are also a number of pitfalls in the treatment with telomerase activating procedures for the whole organism and for longer periods of time. Extended cell lifespan may accumulate rare genetic and epigenetic aberrations that can contribute to malignant transformation. Therefore, novel vector systems have been developed for a 'mild' integration of telomerase into the host genome and loss of the vector in rapidly-proliferating cells. It is currently unclear if this technique can also be used in human beings to treat chronic diseases, such as atherosclerosis.
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Affiliation(s)
- Kathrin Jäger
- Institute of Laboratory Medicine, Clinical Chemistry and Pathobiochemistry, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, Berlin 13353, Germany.
| | - Michael Walter
- Institute of Laboratory Medicine, Clinical Chemistry and Pathobiochemistry, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, Berlin 13353, Germany.
- Labor Berlin-Charité Vivantes Services GmbH, Sylter Str. 2, Berlin 13353, Germany.
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Lye KL, Nordin N, Vidyadaran S, Thilakavathy K. Mesenchymal stem cells: From stem cells to sarcomas. Cell Biol Int 2016; 40:610-8. [PMID: 26992453 DOI: 10.1002/cbin.10603] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 03/14/2016] [Indexed: 12/15/2022]
Abstract
Mesenchymal stem cells (MSCs) have garnered vast interests in clinical settings, especially in regenerative medicine due to their unique properties-they are reliably isolated and expanded from various tissue sources; they are able to differentiate into mesodermal tissues such as bones, cartilages, adipose tissues, and muscles; and they have unique immunosuppressive properties. However, there are some concerns pertaining to the role of MSCs in the human body. On one hand, they are crucial component in the regeneration and repair of the human body. On the contrary, they are shown to transform into sarcomas. Although the exact mechanisms are still unknown, many new leads have pointed to the belief that MSCs do play a role in sarcomagenesis. This review focuses on the current updates and findings of the role of MSCs in their transformation process into sarcomas.
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Affiliation(s)
- Kwan Liang Lye
- Medical Genetics Unit, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia
| | - Norshariza Nordin
- Medical Genetics Unit, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.,Genetics and Regenerative Medicine Research Centre, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia
| | - Sharmili Vidyadaran
- Genetics and Regenerative Medicine Research Centre, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.,Department of Pathology, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia
| | - Karuppiah Thilakavathy
- Medical Genetics Unit, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.,Genetics and Regenerative Medicine Research Centre, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia
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Candini O, Spano C, Murgia A, Grisendi G, Veronesi E, Piccinno MS, Ferracin M, Negrini M, Giacobbi F, Bambi F, Horwitz EM, Conte P, Paolucci P, Dominici M. Mesenchymal progenitors aging highlights a miR-196 switch targeting HOXB7 as master regulator of proliferation and osteogenesis. Stem Cells 2015; 33:939-50. [PMID: 25428821 DOI: 10.1002/stem.1897] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Revised: 10/23/2014] [Accepted: 11/01/2014] [Indexed: 12/12/2022]
Abstract
Human aging is associated with a decrease in tissue functions combined with a decline in stem cells frequency and activity followed by a loss of regenerative capacity. The molecular mechanisms behind this senescence remain largely obscure, precluding targeted approaches to counteract aging. Focusing on mesenchymal stromal/stem cells (MSC) as known adult progenitors, we identified a specific switch in miRNA expression during aging, revealing a miR-196a upregulation which was inversely correlated with MSC proliferation through HOXB7 targeting. A forced HOXB7 expression was associated with an improved cell growth, a reduction of senescence, and an improved osteogenesis linked to a dramatic increase of autocrine basic fibroblast growth factor secretion. These findings, along with the progressive decrease of HOXB7 levels observed during skeletal aging in mice, indicate HOXB7 as a master factor driving progenitors behavior lifetime, providing a better understanding of bone senescence and leading to an optimization of MSC performance.
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Affiliation(s)
- Olivia Candini
- Department of Medical and Surgical Sciences for Children & Adults, University-Hospital of Modena and Reggio Emilia, Modena, Italy
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Wang Y, Chen T, Yan H, Qi H, Deng C, Ye T, Zhou S, Li FR. Role of histone deacetylase inhibitors in the aging of human umbilical cord mesenchymal stem cells. J Cell Biochem 2013; 114:2231-9. [PMID: 23564418 DOI: 10.1002/jcb.24569] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Accepted: 04/02/2013] [Indexed: 01/13/2023]
Affiliation(s)
| | - Tao Chen
- Laboratory of Stem Cell and Cellular Therapy; The Second Clinical Medical College (Shenzhen People's Hospital), Jinan University; Shenzhen; China
| | - Hongjie Yan
- Laboratory of Stem Cell and Cellular Therapy; The Second Clinical Medical College (Shenzhen People's Hospital), Jinan University; Shenzhen; China
| | - Hui Qi
- Laboratory of Stem Cell and Cellular Therapy; The Second Clinical Medical College (Shenzhen People's Hospital), Jinan University; Shenzhen; China
| | - Chunyan Deng
- Laboratory of Stem Cell and Cellular Therapy; The Second Clinical Medical College (Shenzhen People's Hospital), Jinan University; Shenzhen; China
| | - Tao Ye
- Department of Applied Biology and Chemical Technology; The Hong Kong Polytechnic University; Hong Kong SAR; China
| | - Shuyan Zhou
- Laboratory of Stem Cell and Cellular Therapy; The Second Clinical Medical College (Shenzhen People's Hospital), Jinan University; Shenzhen; China
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Gocha ARS, Harris J, Groden J. Alternative mechanisms of telomere lengthening: permissive mutations, DNA repair proteins and tumorigenic progression. Mutat Res 2012; 743-744:142-150. [PMID: 23219603 DOI: 10.1016/j.mrfmmm.2012.11.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Revised: 11/22/2012] [Accepted: 11/24/2012] [Indexed: 01/05/2023]
Abstract
Telomeres protect chromosome termini to maintain genomic stability and regulate cellular lifespan. Maintenance of telomere length is required for neoplastic cells after the acquisition of mutations that deregulate cell cycle control and increase cellular proliferation, and can occur through expression of the enzyme telomerase or in a telomerase-independent manner termed alternative lengthening of telomeres (ALT). The precise mechanisms that govern the activation of ALT or telomerase in tumor cells are unknown, although cellular origin may favor one or the other mechanisms. ALT pathways are incompletely understood to date; however, recent publications have increasingly broadened our understanding of how ALT is activated, how it proceeds, and how it influences tumor growth. Specific mutational events influence ALT activation, as mutations in genes that suppress recombination and/or alterations in the regulation of telomerase expression are associated with ALT. Once engaged, ALT uses DNA repair proteins to maintain telomeres in the absence of telomerase; experiments that manipulate the expression of specific proteins in cells using ALT are illuminating some of its mechanisms. Furthermore, ALT may influence tumor growth, as experimental and clinical data suggest that telomerase expression may favor tumor progression. This review summarizes recent findings in mammalian cells and models, as well as clinical data, that identify the genetic mutations permissive to ALT, the DNA repair proteins involved in ALT mechanisms and the importance of telomere maintenance mechanisms for tumor progression. A comprehensive understanding of the mechanisms that permit tumor cell immortalization will be important for identifying novel therapeutic targets in cancer.
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Affiliation(s)
- April Renee Sandy Gocha
- Department of Molecular Virology, Immunology and Medical Genetics, The Ohio State University College of Medicine, Columbus, OH 43210, United States
| | - Julia Harris
- Department of Molecular Virology, Immunology and Medical Genetics, The Ohio State University College of Medicine, Columbus, OH 43210, United States
| | - Joanna Groden
- Department of Molecular Virology, Immunology and Medical Genetics, The Ohio State University College of Medicine, Columbus, OH 43210, United States.
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Tátrai P, Szepesi Á, Matula Z, Szigeti A, Buchan G, Mádi A, Uher F, Német K. Combined introduction of Bmi-1 and hTERT immortalizes human adipose tissue-derived stromal cells with low risk of transformation. Biochem Biophys Res Commun 2012; 422:28-35. [PMID: 22554522 DOI: 10.1016/j.bbrc.2012.04.088] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Accepted: 04/17/2012] [Indexed: 12/20/2022]
Abstract
Adipose tissue-derived stromal cells (ASCs) are increasingly being studied for their usefulness in regenerative medicine. However, limited life span and donor-dependent variation of primary cells such as ASCs present major hurdles to controlled and reproducible experiments. We therefore aimed to establish immortalized ASC cell lines that provide steady supply of homogeneous cells for in vitro work while retain essential features of primary cells. To this end, combinations of human telomerase reverse transcriptase (hTERT), murine Bmi-1, and SV40 large T antigen (SV40T) were introduced by lentiviral transduction into ASCs. The resulting cell lines ASC(hTERT), ASC(Bmi-1), ASC(Bmi-1+hTERT) and ASC(SV40T+hTERT) were tested for transgene expression, telomerase activity, surface immunomarkers, proliferation, osteogenic and adipogenic differentiation, karyotype, tumorigenicity, and cellular senescence. All cell lines have maintained expression of characteristic surface immunomarkers, and none was tumorigenic. However, ASC(Bmi-1) had limited replicative potential, while the rapidly proliferating ASC(SV40T+hTERT) acquired chromosomal aberrations, departed from MSC phenotype, and lost differentiation capacity. ASC(hTERT) and ASC(hTERT+Bmi-1), on the other hand, preserved all essential MSC features and did not senesce after 100 population doublings. Notably, a subpopulation of ASC(hTERT) also acquired aberrant karyotype and showed signs of transformation after long-term culture. In conclusion, hTERT alone was sufficient to extend the life span of human ASC, but ASC(hTERT) are prone to transformation during extensive subculturing. The combination of Bmi-1 and hTERT successfully immortalized human ASCs without significantly perturbing their phenotype or biological behavior.
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Affiliation(s)
- Péter Tátrai
- Institute of Enzymology, Research Center for Natural Sciences, Hungarian Academy of Sciences, Karolina út 29, H-1113 Budapest, Hungary.
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Lee YK, Park NH, Lee H. Prognostic Value of Alternative Lengthening of Telomeres–Associated Biomarkers in Uterine Sarcoma and Uterine Carcinosarcoma. Int J Gynecol Cancer 2012; 22:434-41. [DOI: 10.1097/igc.0b013e31823ca017] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
ObjectiveA subset of cancer cells maintains telomere lengths in a telomerase-independent manner known as the alternative lengthening of telomeres (ALT). The goal of this study was to evaluate the frequency of ALT in uterine sarcoma and carcinosarcoma and to assess its association with clinical parameters.MethodsRetrospectively collected paraffin blocks from 41 patients with uterine sarcomas and carcinosarcomas were analyzed for ALT-associated promyelocytic leukemia bodies (APBs), which are a significant feature of ALT cells, using combined immunofluorescence and telomere fluorescence in situ hybridization. In addition, a C-circle assay and human telomerase reverse transcriptase immunohistochemistry were performed to support these results.ResultsThe APB assay and C-circle assay indicated that 46.3% (19/41 cases) and 36.4% (8/22 cases) of sarcomas of the uterus, respectively, were positive for ALT. Alternative lengthening of telomerase positivity was correlated with high-grade uterine sarcoma and parameters indicative of an aggressive tumor, such as tumor size (P= 0.033) and mitotic index (P= 0.001); ALT positivity was negatively correlated with human telomerase reverse transcriptase reactivity (P= 0.036). In a survival analysis, the presence of APBs was found to be a poor prognostic factor for disease-free survival (P= 0.018) and overall survival (P= 0.021).ConclusionsAlternative lengthening of telomeres is a prevalent mechanism in uterine sarcomas and carcinosarcomas and is associated with the aggressiveness of the tumor and tumor progression. Importantly, ALT positivity is an indicator of poor prognosis for patients with uterine sarcoma and carcinosarcoma.
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Yang G, Tian J, Feng C, Zhao LL, Liu Z, Zhu J. Trichostatin a promotes cardiomyocyte differentiation of rat mesenchymal stem cells after 5-azacytidine induction or during coculture with neonatal cardiomyocytes via a mechanism independent of histone deacetylase inhibition. Cell Transplant 2011; 21:985-96. [PMID: 21944777 DOI: 10.3727/096368911x593145] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
This study was to investigate the effect of trichostatin A (TSA), a histone deacetylase (HDAC) inhibitor, on cardiac differentiation of bone marrow mesenchymal stem cells (MSCs) in vitro. Rat MSCs were isolated and divided into six groups: 1) control; 2) 5-azacytidine treatment (5-aza, 10 μM); 3) treatment with TSA (100, 300, and 500 nM); 4) treatment with 5-aza followed by incubation with TSA; 5) coculture with neonatal cardiomyocytes (CMs); and 6) treatment with TSA then coculture with CMs. HDAC activity was significantly inhibited in TSA-treated cells with the maximal inhibition after 24 h of exposure to TSA at 300 nM. No changes in HDAC activity were observed in control, 5-aza-treated, or coculture groups. Following 7 days of differentiation, the expression of early cardiac transcription factors GATA-4, NKx2.5, MEF2c, and cardiac troponin T (cTnT) was increased by 6-8 times in the cells in 5-aza-treated, coculture, or TSA-treated groups over control as determined using real-time PCR, immunofluorescence staining, and Western blotting. However, the percent cTnT-positive cells were dramatically different with 0.7% for control, 10% for 5-aza-treated, 25% for coculture, and 4% for TSA-treated group (500 nM). TSA treatment of the cells pretreated with 5-aza or cocultured with CMs dramatically increased the expression of GATA-4, NKx2.5, and MEF2c by 35-50 times over control. The cTnT protein expression was also significantly increased by over threefold by TSA treatment (500 nM) in both 5-aza-treated and coculture group over control. The percent cTnT-positive cells in both 5-aza-pre-treated and coculture groups were significantly increased by TSA treatment after 1 week of differentiation by up to 92.6% (from 10.3% to 19.8%) and 23.9% (from 24.5% to 30.2%), respectively. These data suggested that TSA enhanced the cardiac differentiation of MSCs after 5-aza induction or during coculture with CMs through a mechanism beyond the inhibition of HDAC activity.
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Affiliation(s)
- Ge Yang
- Department of Cell and Molecular Biology, Pediatric Institute of Chongqing Medical University, Chongqing, China
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14
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Poloni A, Maurizi G, Babini L, Serrani F, Berardinelli E, Mancini S, Costantini B, Discepoli G, Leoni P. Human Mesenchymal Stem Cells from Chorionic Villi and Amniotic Fluid are not Susceptible to Transformation after Extensive in Vitro Expansion. Cell Transplant 2011; 20:643-54. [DOI: 10.3727/096368910x536518] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Mesenchymal stem cells (MSCs) are promising candidates for cell therapy and tissue engineering. Increasing evidence suggests that MSCs isolated from fetal tissues are more plastic and grow faster than adult MSCs. In this study, we characterized human mesenchymal progenitor cells from chorionic villi (CV) and amniotic fluid (AF) isolated during the first and second trimesters, respectively, and compared them with adult bone marrow-derived MSCs (BM). We evaluated 10 CV, 10 AF, and 6 BM samples expanded until the MSCs reached senescence. We used discarded cells from prenatal analyses for all the experiments. To evaluate the replicative stability of these cells, we studied the telomerase activity, hTERT gene transcription, and telomere length in these cells. Spontaneous chromosomal alterations were excluded by cytogenetic analysis. We studied the expression of c-myc and p53, tumor-associated genes, at different passage in culture and the capacity of these cells to grow in an anchorage-independent manner by using soft agar assay. We isolated homogeneous populations of spindle-shaped CV, AF, and BM cells expressing mesenchymal immunophenotypic markers throughout the period of expansion. CV cells achieved 14 ± 0.9 logs of expansion in 118 days and AF cells achieved 21 ± 0.9 logs in 118 days, while BM cells achieved 11 × 0.4 logs in 84 days. Despite their high proliferation capacity, fetal MSCs showed no telomerase activity, no hTERT and c-myc transcriptions, and maintained long, stable telomeres. A constant expression level of p53 and a normal karyotype were preserved throughout long-term expansion, suggesting the safety of fetal MSCs. In conclusion, our results indicate that fetal MSCs could be an alternative, more accessible resource for cell therapy and regenerative medicine.
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Affiliation(s)
- Antonella Poloni
- Clinica di Ematologia, Dipartimento Scienze Mediche e Chirurgiche, Università Politecnica delle Marche, Ancona, Italy
| | - Giulia Maurizi
- Clinica di Ematologia, Dipartimento Scienze Mediche e Chirurgiche, Università Politecnica delle Marche, Ancona, Italy
| | - Lucia Babini
- Clinica di Ematologia, Dipartimento Scienze Mediche e Chirurgiche, Università Politecnica delle Marche, Ancona, Italy
| | - Federica Serrani
- Clinica di Ematologia, Dipartimento Scienze Mediche e Chirurgiche, Università Politecnica delle Marche, Ancona, Italy
| | - Eleonora Berardinelli
- Clinica di Ematologia, Dipartimento Scienze Mediche e Chirurgiche, Università Politecnica delle Marche, Ancona, Italy
| | - Stefania Mancini
- Clinica di Ematologia, Dipartimento Scienze Mediche e Chirurgiche, Università Politecnica delle Marche, Ancona, Italy
| | - Benedetta Costantini
- Clinica di Ematologia, Dipartimento Scienze Mediche e Chirurgiche, Università Politecnica delle Marche, Ancona, Italy
| | - Giancarlo Discepoli
- Laboratorio di Citogenetica e Genetica Molecolare, Clinica di Pediatria, Ospedali Riuniti, Ancona, Italy
| | - Pietro Leoni
- Clinica di Ematologia, Dipartimento Scienze Mediche e Chirurgiche, Università Politecnica delle Marche, Ancona, Italy
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15
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Abstract
Human aging is associated with bone loss leading to bone fragility and increased risk of fractures. The cellular and molecular causes of age-related bone loss are current intensive topic of investigation with the aim of identifying new approaches to abolish its negative effects on the skeleton. Age-related osteoblast dysfunction is the main cause of age-related bone loss in both men and women beyond the fifth decade and results from two groups of pathogenic mechanisms: extrinsic mechanisms that are mediated by age-related changes in bone microenvironment including changes in levels of hormones and growth factors, and intrinsic mechanisms caused by the osteoblast cellular senescence. The aim of this review is to provide a summary of the intrinsic senescence mechanisms affecting osteoblastic functions and how they can be targeted to abolish age-related osteoblastic dysfunction and bone loss associated with aging.
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Affiliation(s)
- Moustapha Kassem
- Department of Endocrinology and Metabolism, University Hospital of Odense, Odense, Denmark
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16
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Biomolecular strategies of bone augmentation in spinal surgery. Trends Mol Med 2010; 17:215-22. [PMID: 21195666 DOI: 10.1016/j.molmed.2010.12.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2010] [Revised: 11/27/2010] [Accepted: 12/01/2010] [Indexed: 11/22/2022]
Abstract
Autologous bone grafts and allografts are the most accepted procedures for achieving spinal fusion. Recently, breakthroughs in understanding bone biology have led to the development of novel approaches to address the clinical problem of bone regeneration in an unfavorable environment, while bypassing the drawbacks of traditional treatments, including limited availability, donor site morbidity, risk of disease transmission and reduced osteogenicity. These approaches have also been studied for their effectiveness in reaching successful spinal fusion. This review focuses on the cellular and molecular mechanisms explaining the rationale behind these methods, including bone marrow aspirate and mesenchymal stem cells, platelet-rich plasma, bone morphogenetic proteins and gene therapy, which have opened a promising perspective in the field of bone formation in spinal surgery.
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17
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Wojtyla A, Gladych M, Rubis B. Human telomerase activity regulation. Mol Biol Rep 2010; 38:3339-49. [PMID: 21086176 PMCID: PMC3085100 DOI: 10.1007/s11033-010-0439-x] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2010] [Accepted: 11/08/2010] [Indexed: 01/27/2023]
Abstract
Telomerase has been recognized as a relevant factor distinguishing cancer cells from normal cells. Thus, it has become a very promising target for anticancer therapy. The cell proliferative potential can be limited by replication end problem, due to telomeres shortening, which is overcome in cancer cells by telomerase activity or by alternative telomeres lengthening (ALT) mechanism. However, this multisubunit enzymatic complex can be regulated at various levels, including expression control but also other factors contributing to the enzyme phosphorylation status, assembling or complex subunits transport. Thus, we show that the telomerase expression targeting cannot be the only possibility to shorten telomeres and induce cell apoptosis. It is important especially since the transcription expression is not always correlated with the enzyme activity which might result in transcription modulation failure or a possibility for the gene therapy to be overcome. This review summarizes the current state of knowledge of numerous telomerase regulation mechanisms that take place after telomerase subunits coding genes transcription. Thus we show the possible mechanisms of telomerase activity regulation which might become attractive anticancer therapy targets.
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Affiliation(s)
- Aneta Wojtyla
- Department of Clinical Chemistry and Molecular Diagnostics, Poznan University of Medical Sciences, Przybyszewskiego 49 St, 60-355 Poznan, Poland
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18
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The alternative lengthening of telomeres phenotype in breast carcinoma is associated with HER-2 overexpression. Mod Pathol 2009; 22:1423-31. [PMID: 19734843 DOI: 10.1038/modpathol.2009.125] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Approximately 10-15% of human cancers do not show evidence of telomerase activity, and a subset of these maintain telomere lengths by a recombination-based mechanism termed alternative lengthening of telomeres (ALT). The ALT phenotype, relatively common in certain sarcomas and germ cell tumors, is very rare in carcinomas. In this study we describe evidence for the ALT phenotype in molecular subclasses of breast carcinoma, specifically a subset of cancers with HER-2 overexpression. Tissue microarrays were created from 71 invasive ductal carcinomas of the breast categorized into subclasses, and telomere lengths were directly assessed using fluorescence in situ hybridization with combined promyelocytic leukemia (PML) protein immunofluorescence. The ALT phenotype was identified in 3 of 21 HER-2-positive cases, but in none of the other 50 cases (P=0.023). This is the first direct observation of this mechanism of telomere maintenance in breast carcinoma unrelated to Li-Fraumeni syndrome. The correlation of the ALT phenotype with HER-2 positivity, both of which involve abnormal DNA amplification, suggests a possible common underlying mechanism. This telomere phenotype confers a poor prognosis in some cancers; two of the three cases in our study showed rapid tumor progression, possibly suggesting that it may adversely affect outcome in breast carcinoma as well. As cancers using the ALT pathway are predicted to be resistant to therapies based on telomerase inhibition, these results may have therapeutic consequences.
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19
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A gene expression signature classifying telomerase and ALT immortalization reveals an hTERT regulatory network and suggests a mesenchymal stem cell origin for ALT. Oncogene 2009; 28:3765-74. [PMID: 19684619 PMCID: PMC2875172 DOI: 10.1038/onc.2009.238] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Telomere length is maintained by two known mechanisms, the activation of telomerase or alternative lengthening of telomeres (ALT). The molecular mechanisms regulating the ALT phenotype are poorly understood and it is unknown how the decision of which pathway to activate is made at the cellular level. We have shown earlier that active repression of telomerase gene expression by chromatin remodelling of the promoters is one mechanism of regulation; however, other genes and signalling networks are likely to be required to regulate telomerase and maintain the ALT phenotype. Using gene expression profiling, we have uncovered a signature of 1305 genes to distinguish telomerase-positive and ALT cell lines. By combining this with the gene expression profiles of liposarcoma tissue samples, we refined this signature to 297 genes. A network analysis of known interactions between genes within this signature revealed a regulatory signalling network consistent with a model of human telomerase reverse transcriptase (hTERT) repression in ALT cell lines and liposarcomas. This network expands on our existing knowledge of hTERT regulation and provides a platform to understand differential regulation of hTERT in different tumour types and normal tissues. We also show evidence to suggest a novel mesenchymal stem cell origin for ALT immortalization in cell lines and mesenchymal tissues.
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20
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Placzek MR, Chung IM, Macedo HM, Ismail S, Mortera Blanco T, Lim M, Cha JM, Fauzi I, Kang Y, Yeo DCL, Ma CYJ, Polak JM, Panoskaltsis N, Mantalaris A. Stem cell bioprocessing: fundamentals and principles. J R Soc Interface 2009; 6:209-32. [PMID: 19033137 PMCID: PMC2659585 DOI: 10.1098/rsif.2008.0442] [Citation(s) in RCA: 147] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
In recent years, the potential of stem cell research for tissue engineering-based therapies and regenerative medicine clinical applications has become well established. In 2006, Chung pioneered the first entire organ transplant using adult stem cells and a scaffold for clinical evaluation. With this a new milestone was achieved, with seven patients with myelomeningocele receiving stem cell-derived bladder transplants resulting in substantial improvements in their quality of life. While a bladder is a relatively simple organ, the breakthrough highlights the incredible benefits that can be gained from the cross-disciplinary nature of tissue engineering and regenerative medicine (TERM) that encompasses stem cell research and stem cell bioprocessing. Unquestionably, the development of bioprocess technologies for the transfer of the current laboratory-based practice of stem cell tissue culture to the clinic as therapeutics necessitates the application of engineering principles and practices to achieve control, reproducibility, automation, validation and safety of the process and the product. The successful translation will require contributions from fundamental research (from developmental biology to the 'omics' technologies and advances in immunology) and from existing industrial practice (biologics), especially on automation, quality assurance and regulation. The timely development, integration and execution of various components will be critical-failures of the past (such as in the commercialization of skin equivalents) on marketing, pricing, production and advertising should not be repeated. This review aims to address the principles required for successful stem cell bioprocessing so that they can be applied deftly to clinical applications.
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Affiliation(s)
- Mark R Placzek
- Biological Systems Engineering Laboratory, Centre for Process Systems Engineering, Department of Chemical Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
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21
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Krunic D, Moshir S, Greulich-Bode KM, Figueroa R, Cerezo A, Stammer H, Stark HJ, Gray SG, Nielsen KV, Hartschuh W, Boukamp P. Tissue context-activated telomerase in human epidermis correlates with little age-dependent telomere loss. Biochim Biophys Acta Mol Basis Dis 2009; 1792:297-308. [PMID: 19419690 DOI: 10.1016/j.bbadis.2009.02.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2008] [Revised: 02/06/2009] [Accepted: 02/06/2009] [Indexed: 10/21/2022]
Abstract
Telomerase- and telomere length regulation in normal human tissues is still poorly understood. We show here that telomerase is expressed in the epidermis in situ independent of age but was repressed upon the passaging of keratinocytes in monolayer culture. However, when keratinocytes were grown in organotypic cultures (OTCs), telomerase was re-established, indicating that telomerase activity is not merely proliferation-associated but is regulated in a tissue context-dependent manner in human keratinocytes. While not inducible by growth factors, treatment with the histone deacetylation inhibitor FK228 restored telomerase activity in keratinocytes grown in monolayer cultures. Accordingly, CHIP analyses demonstrated an acetylated, active hTERT promoter in the epidermis in situ and in the epidermis of OTCs but a deacetylated, silenced hTERT promoter with subsequent propagation in monolayer culture suggesting that histone acetylation is part of the regulatory program to guarantee hTERT expression/telomerase activity in the epidermis. In agreement with the loss of telomerase activity, telomeres shortened during continuous propagation in monolayer culture by an average of approximately 70 base pairs (bp) per population doubling (pd). However, telomere erosion varied strongly between different keratinocyte strains and even between individual cells within the same culture, thereby arguing against a defined rate of telomere loss per replication cycle. In the epidermis in situ, as determined from early-passage keratinocytes and tissue sections from different age donors, we calculated a telomere loss of only approximately 25 bp per year. Since we determined the same rate for the non-regenerating melanocytes and dermal fibroblasts, our data suggest that in human epidermis telomerase is a protective mechanism against excessive telomere loss during the life-long regeneration.
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Affiliation(s)
- Damir Krunic
- Division of Genetics of Skin Carcinogenesis, German Cancer Research Center, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 280, D-69120 Heidelberg, Germany
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22
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Bellantuono I, Aldahmash A, Kassem M. Aging of marrow stromal (skeletal) stem cells and their contribution to age-related bone loss. Biochim Biophys Acta Mol Basis Dis 2009; 1792:364-70. [PMID: 19419706 DOI: 10.1016/j.bbadis.2009.01.008] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2008] [Revised: 01/19/2009] [Accepted: 01/21/2009] [Indexed: 01/01/2023]
Abstract
Marrow stromal cells (MSC) are thought to be stem cells with osteogenic potential and therefore responsible for the repair and maintenance of the skeleton. Age related bone loss is one of the most prevalent diseases in the elder population. It is controversial whether MSC undergo a process of aging in vivo, leading to decreased ability to form and maintain bone homeostasis with age. In this review we summarize evidence of MSC involvement in age related bone loss and suggest new emerging targets for intervention.
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23
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Final checkup of neoplastic DNA replication: Evidence for failure in decision-making at the mitotic cell cycle checkpoint G1/S. Exp Hematol 2008; 36:1403-16. [DOI: 10.1016/j.exphem.2008.07.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2008] [Revised: 07/29/2008] [Accepted: 07/29/2008] [Indexed: 11/24/2022]
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24
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Controversial issue: is it safe to employ mesenchymal stem cells in cell-based therapies? Exp Gerontol 2008; 43:1018-23. [PMID: 18694815 DOI: 10.1016/j.exger.2008.07.004] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2008] [Revised: 07/11/2008] [Accepted: 07/15/2008] [Indexed: 12/18/2022]
Abstract
The prospective clinical use of multipotent mesenchymal stromal stem cells (MSC) holds enormous promise for the treatment of a large number of degenerative and age-related diseases. However, the challenges and risks for cell-based therapies are multifaceted. The risks for patients receiving stem cells, which have been expanded in vitro in the presence of xenogenic compounds, can hardly be anticipated and methods for the culture and manipulation of "safe" MSC ex vivo are being investigated. During in vitro expansion, stem cells experience a long replicative history and are thus subject to damage from intracellular and extracellular influences. While murine MSC are prone to cellular transformation in culture, human MSC do not transform. One reason for this striking difference is that during long-term culture, human MSC finally become replicatively senescent. In consequence, this greatly restricts their proliferation and differentiation efficiency. It however also limits the yield of sufficient numbers of cells needed for therapy. Another issue is to eliminate contamination of expanding cells with serum-bound pathogenic agents in order to reduce the risks for infection. A recent technical advancement, which applies human serum platelet lysates as an alternative source for growth factors and essential supplements, allows the unimpaired proliferation of MSC in the absence of animal sera. Here, we present an update regarding cellular senescence of MSC and recent insights concerning potential risks associated with their clinical use.
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25
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Cairney CJ, Hoare SF, Daidone MG, Zaffaroni N, Keith WN. High level of telomerase RNA gene expression is associated with chromatin modification, the ALT phenotype and poor prognosis in liposarcoma. Br J Cancer 2008; 98:1467-74. [PMID: 18414473 PMCID: PMC2361713 DOI: 10.1038/sj.bjc.6604328] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Telomere length is maintained by two known mechanisms, activation of telomerase or alternative lengthening of telomeres (ALT). The ALT pathway is more commonly activated in tumours of mesenchymal origin, although the mechanisms involved in the decision of a cell to activate either telomerase or ALT are unknown at present and no molecular markers exist to define the ALT phenotype. We have previously shown an association between chromatin remodelling, telomerase gene expression and ALT in cell line models. Here, we evaluate these findings and investigate their prognostic significance in a panel of liposarcoma tissue samples to understand the biology underlying the ALT phenotype. Liposarcoma samples were split into three groups: telomerase positive (Tel+); ALT positive; ALT−/Tel−. Differences in telomerase gene expression were evident between the groups with increased expression of hTR in ALT and Tel+ compared to ALT−/Tel− samples and increased hTERT in Tel+ samples only. Investigation of a small panel of chromatin modifications revealed significantly increased binding of acetyl H3 in association with hTR expression. We confirm that the presence of the ALT phenotype is associated with poor prognosis and in addition, for the first time, we show a direct association between hTR expression and poor prognosis in liposarcoma patients.
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Affiliation(s)
- C J Cairney
- Centre for Oncology and Applied Pharmacology, University of Glasgow, Cancer Research UK Beatson Laboratories, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
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26
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Abstract
This review focuses on the interaction between multipotent stromal cells (MSCs) and carcinoma and the possible use of MSCs in cell-based anticancer therapies. MSCs are present in multiple tissues and are defined as cells displaying the ability to differentiate in multiple lineages, including chondrocytes, osteoblasts, and adipocytes. Recent evidence also suggests that they could play a role in the progression of carcinogenesis and that MSCs could migrate toward primary tumors and metastatic sites. It is possible that MSCs could also be involved in the early stages of carcinogenesis through spontaneous transformation. In addition, it is thought that MSCs can modulate tumor growth and metastasis, although this issue remains controversial and not well understood. The immunosuppressive properties and proangiogenic properties of MSCs account, at least in part, for their effects on cancer development. On the other hand, cancer cells also have the ability to enhance MSC migration. This complex dialog between MSCs and cancer cells is certainly critical for the outcome of tumor development. Interestingly, several studies have shown that MSCs engineered to express antitumor factors could be an innovative choice as a cell-mediated gene therapy to counteract tumor growth. More evidence will be needed to understand how MSCs positively or negatively modulate carcinogenesis and to evaluate the safety of MSC use in cell-mediated gene strategies. Disclosure of potential conflicts of interest is found at the end of this article.
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Affiliation(s)
- Gwendal Lazennec
- Institut National de la Santé et de la Recherche Médicale, Montpellier, France.
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27
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Abstract
One of the hallmarks of advanced malignancies is continuous cell growth and this almost universally correlates with the reactivation of telomerase. Although there is still much we do not understand about the regulation of telomerase, it remains a very attractive and novel target for cancer therapeutics. Several clinical trials have been initiated, and in this review we highlight some of the most promising approaches and conclude by speculating on the role of telomerase in cancer stem cells.
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Affiliation(s)
- J W Shay
- Department of Cell Biology, University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Boulevard, Dallas, TX 75390-9030, USA.
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28
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Rubio D, Garcia S, Paz MF, De la Cueva T, Lopez-Fernandez LA, Lloyd AC, Garcia-Castro J, Bernad A. Molecular characterization of spontaneous mesenchymal stem cell transformation. PLoS One 2008; 3:e1398. [PMID: 18167557 PMCID: PMC2151133 DOI: 10.1371/journal.pone.0001398] [Citation(s) in RCA: 125] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2006] [Accepted: 12/07/2007] [Indexed: 01/04/2023] Open
Abstract
Background We previously reported the in vitro spontaneous transformation of human mesenchymal stem cells (MSC) generating a population with tumorigenic potential, that we termed transformed mesenchymal cells (TMC). Methodology/Principal Findings Here we have characterized the molecular changes associated with TMC generation. Using microarrays techniques we identified a set of altered pathways and a greater number of downregulated than upregulated genes during MSC transformation, in part due to the expression of many untranslated RNAs in MSC. Microarray results were validated by qRT-PCR and protein detection. Conclusions/Significance In our model, the transformation process takes place through two sequential steps; first MSC bypass senescence by upregulating c-myc and repressing p16 levels. The cells then bypass cell crisis with acquisition of telomerase activity, Ink4a/Arf locus deletion and Rb hyperphosphorylation. Other transformation-associated changes include modulation of mitochondrial metabolism, DNA damage-repair proteins and cell cycle regulators. In this work we have characterized the molecular mechanisms implicated in TMC generation and we propose a two-stage model by which a human MSC becomes a tumor cell.
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Affiliation(s)
- Daniel Rubio
- Department of Immunology and Oncology, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CSIC), Universidad Autónoma de Madrid, Madrid, Spain
| | - Silvia Garcia
- Department of Immunology and Oncology, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CSIC), Universidad Autónoma de Madrid, Madrid, Spain
| | - Maria F. Paz
- Department of Immunology and Oncology, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CSIC), Universidad Autónoma de Madrid, Madrid, Spain
| | - Teresa De la Cueva
- Department of Immunology and Oncology, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CSIC), Universidad Autónoma de Madrid, Madrid, Spain
| | | | - Alison C. Lloyd
- Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
| | - Javier Garcia-Castro
- Department of Immunology and Oncology, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CSIC), Universidad Autónoma de Madrid, Madrid, Spain
- Andalusian Stem Cell Bank, Granada, Spain
| | - Antonio Bernad
- Department of Immunology and Oncology, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CSIC), Universidad Autónoma de Madrid, Madrid, Spain
- * To whom correspondence should be addressed. E-mail:
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29
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Telomere stability and telomerase in mesenchymal stem cells. Biochimie 2008; 90:33-40. [DOI: 10.1016/j.biochi.2007.09.005] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2007] [Accepted: 09/10/2007] [Indexed: 01/25/2023]
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30
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Cairney CJ, Keith WN. Telomerase redefined: Integrated regulation of hTR and hTERT for telomere maintenance and telomerase activity. Biochimie 2008; 90:13-23. [PMID: 17854971 DOI: 10.1016/j.biochi.2007.07.025] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2007] [Accepted: 07/23/2007] [Indexed: 10/23/2022]
Abstract
Telomerase activity is dependent on the expression of 2 main core component genes, hTERT, which encodes the catalytic component and hTR (also called TERC), which encodes the RNA component. The correlation between telomerase activity and carcinogenesis has made this molecule of great interest in cancer research, however in order to fully understand the regulation of telomerase the mechanisms controlling both telomerase genes need to be studied. Some of these mechanisms of regulation have begun to emerge, however many more remain to be deciphered. For many years hTERT has been regarded as the limiting component of telomerase and much of the research in this field has focussed on its regulation, however it was clear from an early stage that hTR expression was also tightly regulated in normal cells and disease. More recently evidence from biochemistry, promoter studies and mouse models has been steadily increasing for a role for hTR as a limiting and essential component for telomerase activity and telomere maintenance. Perhaps the time has come to redefine our view of telomerase regulation. Knowledge of the mechanisms controlling both telomerase genes in normal systems and cancer may aid our understanding of the role of telomerase in carcinogenesis or highlight potential areas for therapeutic intervention. Here we review the essential requirement of hTR for telomere maintenance and telomerase activity in normal tissues and disease and focus on recent advances in our understanding of hTR regulation in relation to hTERT.
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Affiliation(s)
- C J Cairney
- Centre for Oncology and Applied Pharmacology, University of Glasgow, Cancer Research UK Beatson Laboratories, Bearsden, Glasgow G61 1BD, UK
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Saretzki G, Walter T, Atkinson S, Passos JF, Bareth B, Keith WN, Stewart R, Hoare S, Stojkovic M, Armstrong L, von Zglinicki T, Lako M. Downregulation of multiple stress defense mechanisms during differentiation of human embryonic stem cells. Stem Cells 2007; 26:455-64. [PMID: 18055443 DOI: 10.1634/stemcells.2007-0628] [Citation(s) in RCA: 190] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Evolutionary theory predicts that cellular maintenance, stress defense, and DNA repair mechanisms should be most active in germ line cells, including embryonic stem cells that can differentiate into germ line cells, whereas it would be energetically unfavorable to keep these up in mortal somatic cells. We tested this hypothesis by examining telomere maintenance, oxidative stress generation, and genes involved in antioxidant defense and DNA repair during spontaneous differentiation of two human embryonic stem cell lines. Telomerase activity was quickly downregulated during differentiation, probably due to deacetylation of histones H3 and H4 at the hTERT promoter and deacetylation of histone H3 at hTR promoter. Telomere length decreased accordingly. Mitochondrial superoxide production and cellular levels of reactive oxygen species increased as result of increased mitochondrial biogenesis. The expression of major antioxidant genes was downregulated despite this increased oxidative stress. DNA damage levels increased during differentiation, whereas expression of genes involved in different types of DNA repair decreased. These results confirm earlier data obtained during mouse embryonic stem cell differentiation and are in accordance with evolutionary predictions.
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Affiliation(s)
- Gabriele Saretzki
- Crucible Lab, Institute of Human Genetics, Central Parkway, Newcastle upon Tyne NE1 3BZ, United Kingdom.
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Costa A, Daidone MG, Daprai L, Villa R, Cantù S, Pilotti S, Mariani L, Gronchi A, Henson JD, Reddel RR, Zaffaroni N. Telomere maintenance mechanisms in liposarcomas: association with histologic subtypes and disease progression. Cancer Res 2007; 66:8918-24. [PMID: 16951210 DOI: 10.1158/0008-5472.can-06-0273] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Human cancer cells maintain telomeres by telomerase activity (TA) or by alternative lengthening of telomeres (ALT). We proposed to define the prevalence of the two telomere maintenance mechanisms (TMM), to assess their association with histology, and to compare their prognostic relevance in a series of 93 patients with liposarcoma. ALT was detected by assaying ALT-associated promyelocytic leukemia nuclear bodies and TA was assayed using the telomeric repeat amplification protocol. ALT or TA was found in 25.9% or 26.6% of 139 tested liposarcoma lesions, respectively. Three lesions were ALT+/TA+ whereas approximately 50% of lesions did not show any known TMM. TMM phenotype was consistent during disease progression. ALT was prevalent in dedifferentiated and in grade 3 liposarcomas whereas TA prevailed in most round-cell myxoid and in grade 2 liposarcomas. ALT and TA incidence was similar in primary and recurrent lesions whereas metastases were more frequently TA+ than ALT+ (59% versus 18%; P = 0.04). TMM presence negatively affected patient prognosis (P = 0.001): increased mortality was associated with positivity for TA (P = 0.038) or ALT (P < 0.0001) compared with TMM absence. ALT proved to be a stronger prognostic discriminant of increased mortality than TA even when adjusted for tumor location, grade, and histology (hazard ratio for cause-specific death, 3.58 versus 1.15). Our results indicate that ALT can support fully malignant liposarcomas and is associated with unfavorable disease outcome.
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Affiliation(s)
- Aurora Costa
- Department of Experimental Oncology and Laboratories, Istituto Nazionale per lo Studio e la Cura dei Tumori, Milano, Italy
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Abstract
Mesenchymal stem cells (MSC) are a group of clonogenic cells present among the bone marrow stroma and capable of multilineage differentiation into mesoderm-type cells such as osteoblasts, adipocytes and chondrocytes. Due to their ease of isolation and their differentiation potential, MSC are being introduced into clinical medicine in variety of applications and through different ways of administration. Here, we discuss approaches for isolation, characterization and directing differentiation of human mesenchymal stem cells (hMSC). An update of the current clinical use of the cells is also provided.
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Kassem M, Abdallah BM. Human bone-marrow-derived mesenchymal stem cells: biological characteristics and potential role in therapy of degenerative diseases. Cell Tissue Res 2007; 331:157-63. [PMID: 17896115 DOI: 10.1007/s00441-007-0509-0] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2007] [Accepted: 09/03/2007] [Indexed: 10/22/2022]
Abstract
Mesenchymal stem cells (MSC) are a group of cells present in bone-marrow stroma and the stroma of various organs with the capacity for mesoderm-like cell differentiation into, for example, osteoblasts, adipocytes, and chondrocytes. MSC are being introduced in the clinic for the treatment of a variety of clinical conditions. The aim of this review is to provide an update regarding the biology of MSC, their identification and culture, and mechanisms controlling their proliferation and differentiation. We also review the current status of their clinical use. Areas in which research is needed to enhance the clinical use of MSC are emphasized.
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Affiliation(s)
- Moustapha Kassem
- Department of Endocrinology and Metabolism, University Hospital of Odense, 5000, Odense C, Denmark.
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Tárkányi I, Aradi J. Pharmacological intervention strategies for affecting telomerase activity: future prospects to treat cancer and degenerative disease. Biochimie 2007; 90:156-72. [PMID: 17945408 DOI: 10.1016/j.biochi.2007.09.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2007] [Accepted: 09/04/2007] [Indexed: 12/20/2022]
Abstract
Telomerase enzyme is a ribonucleoprotein maintaining the length of the telomeres by adding G-rich repeats to the end of the eukaryotic chromosomes. Normal human somatic cells, cultured in vitro, have a strictly limited proliferative potential undergoing senescence after about 50-70 population doublings. In contrast, most of the tumor cells have unlimited replicative potential. Although the mechanisms of immortalization are not understood completely at a genetic level, the key role of the telomere/telomerase system in the process is clear. The DNA replication machinery is not able to replicate fully the DNA at the very end of the chromosomes; therefore, about 50-200 nucleotides are lost during each of the replication cycles resulting in a gradual decrease of telomere length. Critically short telomere induces senescence, subsequent crisis and cell death. In tumor cells, however, the telomerase enzyme prevents the formation of critically short telomeres, adding GGTTAG repeats to the 3' end of the chromosomes immortalizing the cells. Immortality is one of the hallmarks of cancer. Besides the catalytic activity dependent telomere maintenance, catalytic activity-independent effects of telomerase may also be involved in the regulation of cell cycle. The telomere/telomerase system offers two possibilities to intervene the proliferative activity of the cell: (1) inhibition the telomere maintenance by inhibiting the telomerase activity; (2) activating the residual telomerase enzyme or inducing telomerase expression. Whilst the former approach could abolish the limitless replicative potential of malignant cells, the activation of telomerase might be utilized for treating degenerative diseases. Here, we review the current status of telomerase therapeutics, summarizing the activities of those pharmacological agents which either inhibit or activate the enzyme. We also discuss the future opportunities and challenges of research on pharmacological intervention of telomerase activity.
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Affiliation(s)
- I Tárkányi
- 3rd Department of Internal Medicine, University of Debrecen, 22 Moricz Zsigmond Krt., Debrecen 4004, Hungary
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Atkinson SP, Keith WN. Epigenetic control of cellular senescence in disease: opportunities for therapeutic intervention. Expert Rev Mol Med 2007; 9:1-26. [PMID: 17352843 DOI: 10.1017/s1462399407000269] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Understanding how senescence is established and maintained is an important area of study both for normal cell physiology and in tumourigenesis. Modifications to N-terminal tails of histone proteins, which can lead to chromatin remodelling, appear to be key to the regulation of the senescence phenotype. Epigenetic mechanisms such as modification of histone proteins have been shown to be sufficient to regulate gene expression levels and specific gene promoters can become epigenetically altered at senescence. This suggests that epigenetic mechanisms are important in senescence and further suggests epigenetic deregulation could play an important role in the bypass of senescence and the acquisition of a tumourigenic phenotype. Tumour suppressor proteins and cellular senescence are intimately linked and such proteins are now known to regulate gene expression through chromatin remodelling, again suggesting a link between chromatin modification and cellular senescence. Telomere dynamics and the expression of the telomerase genes are also both implicitly linked to senescence and tumourigenesis, and epigenetic deregulation of the telomerase gene promoters has been identified as a possible mechanism for the activation of telomere maintenance mechanisms in cancer. Recent studies have also suggested that epigenetic deregulation in stem cells could play an important role in carcinogenesis, and new models have been suggested for the attainment of tumourigenesis and bypass of senescence. Overall, proper regulation of the chromatin environment is suggested to have an important role in the senescence pathway, such that its deregulation could lead to tumourigenesis.
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Affiliation(s)
- Stuart P Atkinson
- Centre for Oncology and Applied Pharmacology, University of Glasgow, Cancer Research UK Beatson Laboratories, Bearsden, Glasgow, G61 1BD, UK
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