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DNA methylation of the TERT promoter and its impact on human cancer. Curr Opin Genet Dev 2020; 60:17-24. [PMID: 32114294 DOI: 10.1016/j.gde.2020.02.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 01/29/2020] [Accepted: 02/02/2020] [Indexed: 02/07/2023]
Abstract
Telomere maintenance is a hallmark of human cancer that enables replicative immortality. Most cancer cells acquire telomere maintenance by telomerase activation through expression of telomerase reverse transcriptase (TERT), a rate-limiting component of the telomerase holoenzyme. Although multiple cancer-specific genetic alterations such as gain of TERT copy number and recurrent TERT promoter mutations (TPM) have been identified, the majority of cancers still express TERT via unknown mechanisms. In the last decade, DNA methylation of the TERT promoter emerged as a putative epigenetic regulatory mechanism of telomerase activation in cancer. Here, we comparatively discuss studies that investigated the DNA methylation landscape of the TERT promoter. We further review the biological and clinical impacts of TERT promoter hypermethylation in cancer and provide insight into future applications of this phenomenon.
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Leão R, Apolónio JD, Lee D, Figueiredo A, Tabori U, Castelo-Branco P. Mechanisms of human telomerase reverse transcriptase (hTERT) regulation: clinical impacts in cancer. J Biomed Sci 2018. [PMID: 29526163 PMCID: PMC5846307 DOI: 10.1186/s12929-018-0422-8] [Citation(s) in RCA: 150] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Background Limitless self-renewal is one of the hallmarks of cancer and is attained by telomere maintenance, essentially through telomerase (hTERT) activation. Transcriptional regulation of hTERT is believed to play a major role in telomerase activation in human cancers. Main body The dominant interest in telomerase results from its role in cancer. The role of telomeres and telomere maintenance mechanisms is well established as a major driving force in generating chromosomal and genomic instability. Cancer cells have acquired the ability to overcome their fate of senescence via telomere length maintenance mechanisms, mainly by telomerase activation. hTERT expression is up-regulated in tumors via multiple genetic and epigenetic mechanisms including hTERT amplifications, hTERT structural variants, hTERT promoter mutations and epigenetic modifications through hTERT promoter methylation. Genetic (hTERT promoter mutations) and epigenetic (hTERT promoter methylation and miRNAs) events were shown to have clinical implications in cancers that depend on hTERT activation. Knowing that telomeres are crucial for cellular self-renewal, the mechanisms responsible for telomere maintenance have a crucial role in cancer diseases and might be important oncological biomarkers. Thus, rather than quantifying TERT expression and its correlation with telomerase activation, the discovery and the assessment of the mechanisms responsible for TERT upregulation offers important information that may be used for diagnosis, prognosis, and treatment monitoring in oncology. Furthermore, a better understanding of these mechanisms may promote their translation into effective targeted cancer therapies. Conclusion Herein, we reviewed the underlying mechanisms of hTERT regulation, their role in oncogenesis, and the potential clinical applications in telomerase-dependent cancers.
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Affiliation(s)
- Ricardo Leão
- Division of Urology, Department of Surgery Princess Margaret Cancer Centre, University Health Network, 610 University Ave 3-130, Toronto, ON, M5G 2M9, Canada. .,Arthur and Sonia Labatt Brain Tumor Research Center, The Hospital for Sick Children, University of Toronto, 555 University Avenue, Toronto, ON, M5G 1X8, Canada. .,Faculty of Medicine, University of Coimbra, R. Larga, 3004-504, Coimbra, Coimbra, Portugal. .,Department of Urology, Coimbra University Hospital, Coimbra, Portugal.
| | - Joana Dias Apolónio
- Regenerative Medicine Program, Department of Biomedical Sciences and Medicine, University of Algarve, Edifício 2 - Ala Norte, 8005-139, Faro, Portugal.,Centre for Biomedical Research (CBMR), University of Algarve, Faro, Portugal.,Algarve Biomedical Center, Campus Gambelas, Faro, Portugal
| | - Donghyun Lee
- Arthur and Sonia Labatt Brain Tumor Research Center, The Hospital for Sick Children, University of Toronto, 555 University Avenue, Toronto, ON, M5G 1X8, Canada
| | - Arnaldo Figueiredo
- Faculty of Medicine, University of Coimbra, R. Larga, 3004-504, Coimbra, Coimbra, Portugal.,Department of Urology, Coimbra University Hospital, Coimbra, Portugal
| | - Uri Tabori
- Arthur and Sonia Labatt Brain Tumor Research Center, The Hospital for Sick Children, University of Toronto, 555 University Avenue, Toronto, ON, M5G 1X8, Canada.,Division of Haematology/Oncology, The Hospital for Sick Children, 555 University Avenue, Toronto, M5G 1X8ON, Canada
| | - Pedro Castelo-Branco
- Regenerative Medicine Program, Department of Biomedical Sciences and Medicine, University of Algarve, Edifício 2 - Ala Norte, 8005-139, Faro, Portugal.,Centre for Biomedical Research (CBMR), University of Algarve, Faro, Portugal.,Algarve Biomedical Center, Campus Gambelas, Faro, Portugal
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Kumar A, Nilednu P, Kumar A, Sharma NK. Epigenetic perturbation driving asleep telomerase reverse transcriptase: Possible therapeutic avenues in carcinoma. Tumour Biol 2017; 39:1010428317695951. [DOI: 10.1177/1010428317695951] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
In the last decade, implications of human telomerase reverse transcriptase (hTERT), a component of ribonucleoprotein telomerase in aging, senescence, and stem cell are highly evident. Besides, the activation of hTERT is also being documented several cancer types including carcinoma. The awakening of telomerase during carcinoma initiation and development is being seen with different perspectives including genetic and epigenetic tools and events. In view of several tumor progenitors genes (also referred as epigenetic mediators), telomerase is placed as key enzyme to achieve the carcinoma phenotype and sustain during the progression. It is true that swaying of telomerase in carcinoma could be facilitated with dedicated set of epigenetic modulators and modifiers players. These epigenetic alterations are heritable, potentially reversible, and seen as the epigenetic signature of carcinoma. Several papers converge to suggest that DNA methylation, histone modification, and small non-coding RNAs are the widely appreciated epigenetic changes towards hTERT modulation. In this review, we summarize the contribution of epigenetic factors in the telomerase activation and discuss potential avenues to achieve therapeutic intervention in carcinoma.
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Affiliation(s)
- Ajay Kumar
- Cancer and Translational Research Lab, Department of Biotechnology, Dr. D. Y. Patil Biotechnology & Bioinformatics Institute, Dr. D. Y. Patil Vidyapeeth, Pune, Pune, India
| | - Pritish Nilednu
- Cancer and Translational Research Lab, Department of Biotechnology, Dr. D. Y. Patil Biotechnology & Bioinformatics Institute, Dr. D. Y. Patil Vidyapeeth, Pune, Pune, India
| | - Azad Kumar
- Cancer and Translational Research Lab, Department of Biotechnology, Dr. D. Y. Patil Biotechnology & Bioinformatics Institute, Dr. D. Y. Patil Vidyapeeth, Pune, Pune, India
| | - Nilesh Kumar Sharma
- Cancer and Translational Research Lab, Department of Biotechnology, Dr. D. Y. Patil Biotechnology & Bioinformatics Institute, Dr. D. Y. Patil Vidyapeeth, Pune, Pune, India
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Lee S, Borah S, Bahrami A. Detection of Aberrant TERT Promoter Methylation by Combined Bisulfite Restriction Enzyme Analysis for Cancer Diagnosis. J Mol Diagn 2017; 19:378-386. [PMID: 28284778 DOI: 10.1016/j.jmoldx.2017.01.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Revised: 12/13/2016] [Accepted: 01/05/2017] [Indexed: 12/12/2022] Open
Abstract
Aberrant CpG dinucleotide methylation in a specific region of the telomerase reverse transcriptase (TERT) promoter is associated with increased TERT mRNA levels and malignancy in several cancer types. However, routine screening of this region to aid cancer diagnosis can be challenging because i) several established methylation assays may inaccurately report on hypermethylation of this particular region, ii) interpreting the results of methylation assays can sometimes be difficult for clinical laboratories, and iii) use of high-throughput methylation assays for a few patient samples can be cost prohibitive. Herein, we describe the use of combined bisulfite restriction enzyme analysis (COBRA) as a diagnostic tool for detecting the hypermethylated TERT promoter using in vitro methylated and unmethylated genomic DNA as well as genomic DNA from four melanomas and two benign melanocytic lesions. We compare COBRA with MassARRAY, a more commonly used high-throughput approach, in screening for promoter hypermethylation in 28 formalin-fixed, paraffin-embedded neuroblastoma samples. COBRA sensitively and specifically detected samples with hypermethylated TERT promoter and was as effective as MassARRAY at differentiating high-risk from benign or low-risk tumors. This study demonstrates the utility of this low-cost, technically straightforward, and easily interpretable assay for cancer diagnosis in tumors of an ambiguous nature.
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Affiliation(s)
- Seungjae Lee
- Department of Pathology, St. Jude Children's Research Hospital, Memphis, Tennessee
| | - Sumit Borah
- Department of Pathology, St. Jude Children's Research Hospital, Memphis, Tennessee
| | - Armita Bahrami
- Department of Pathology, St. Jude Children's Research Hospital, Memphis, Tennessee.
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Zhang F, Cheng D, Wang S, Zhu J. Human Specific Regulation of the Telomerase Reverse Transcriptase Gene. Genes (Basel) 2016; 7:genes7070030. [PMID: 27367732 PMCID: PMC4962000 DOI: 10.3390/genes7070030] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Revised: 06/15/2016] [Accepted: 06/17/2016] [Indexed: 12/19/2022] Open
Abstract
Telomerase, regulated primarily by the transcription of its catalytic subunit telomerase reverse transcriptase (TERT), is critical for controlling cell proliferation and tissue homeostasis by maintaining telomere length. Although there is a high conservation between human and mouse TERT genes, the regulation of their transcription is significantly different in these two species. Whereas mTERT expression is widely detected in adult mice, hTERT is expressed at extremely low levels in most adult human tissues and cells. As a result, mice do not exhibit telomere-mediated replicative aging, but telomere shortening is a critical factor of human aging and its stabilization is essential for cancer development in humans. The chromatin environment and epigenetic modifications of the hTERT locus, the binding of transcriptional factors to its promoter, and recruitment of nucleosome modifying complexes all play essential roles in restricting its transcription in different cell types. In this review, we will discuss recent progress in understanding the molecular mechanisms of TERT regulation in human and mouse tissues and cells, and during cancer development.
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Affiliation(s)
- Fan Zhang
- Department of Pharmaceutical Sciences, Washington State University College of Pharmacy, PO Box 1495, Spokane, WA 99210, USA.
| | - De Cheng
- Department of Pharmaceutical Sciences, Washington State University College of Pharmacy, PO Box 1495, Spokane, WA 99210, USA.
| | - Shuwen Wang
- Department of Pharmaceutical Sciences, Washington State University College of Pharmacy, PO Box 1495, Spokane, WA 99210, USA.
| | - Jiyue Zhu
- Department of Pharmaceutical Sciences, Washington State University College of Pharmacy, PO Box 1495, Spokane, WA 99210, USA.
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