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Ranches G, Zeidler M, Kessler R, Hoelzl M, Hess MW, Vosper J, Perco P, Schramek H, Kummer KK, Kress M, Krogsdam A, Rudnicki M, Mayer G, Huettenhofer A. Exosomal mitochondrial tRNAs and miRNAs as potential predictors of inflammation in renal proximal tubular epithelial cells. MOLECULAR THERAPY. NUCLEIC ACIDS 2022; 28:794-813. [PMID: 35664695 PMCID: PMC9136061 DOI: 10.1016/j.omtn.2022.04.035] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 04/28/2022] [Indexed: 12/02/2022]
Abstract
Exosomes have emerged as a valuable repository of novel biomarkers for human diseases such as chronic kidney disease (CKD). From a healthy control group, we performed microRNA (miRNA) profiling of urinary exosomes and compared it with a cell culture model of renal proximal tubular epithelial cells (RPTECs). Thereby, a large fraction of abundant urinary exosomal miRNAs could also be detected in exosomes derived from RPTECs, indicating them as a suitable model system for investigation of CKD. We subsequently analyzed exosomes from RPTECs in pro-inflammatory and pro-fibrotic states, mimicking some aspects of CKD. Following cytokine treatment, we observed a significant increase in exosome release and identified 30 dysregulated exosomal miRNAs, predominantly associated with the regulation of pro-inflammatory and pro-fibrotic-related pathways. In addition to miRNAs, we also identified 16 dysregulated exosomal mitochondrial RNAs, highlighting a pivotal role of mitochondria in sensing renal inflammation. Inhibitors of exosome biogenesis and release significantly altered the abundance of selected candidate miRNAs and mitochondrial RNAs, thus suggesting distinct sorting mechanisms of different non-coding RNA (ncRNA) species into exosomes. Hence, these two exosomal ncRNA species might be employed as potential indicators for predicting the pathogenesis of CKD and also might enable effective monitoring of the efficacy of CKD treatment.
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Affiliation(s)
- Glory Ranches
- Division of Genomics and RNomics, Biocenter, Medical University of Innsbruck, Innsbruck 6020, Austria
| | - Maximilian Zeidler
- Institute of Physiology, Medical University of Innsbruck, Innsbruck 6020, Austria
| | - Roman Kessler
- Division of Genomics and RNomics, Biocenter, Medical University of Innsbruck, Innsbruck 6020, Austria
| | - Martina Hoelzl
- Division of Genomics and RNomics, Biocenter, Medical University of Innsbruck, Innsbruck 6020, Austria
| | - Michael W. Hess
- Institute of Histology and Embryology, Medical University of Innsbruck, Innsbruck 6020, Austria
| | - Jonathan Vosper
- Division of Medical Biochemistry, Biocenter, Medical University of Innsbruck, Innsbruck 6020, Austria
| | - Paul Perco
- Department of Internal Medicine IV (Nephrology and Hypertension), Medical University of Innsbruck, Innsbruck 6020, Austria
| | - Herbert Schramek
- Department of Internal Medicine IV (Nephrology and Hypertension), Medical University of Innsbruck, Innsbruck 6020, Austria
| | - Kai K. Kummer
- Institute of Physiology, Medical University of Innsbruck, Innsbruck 6020, Austria
| | - Michaela Kress
- Institute of Physiology, Medical University of Innsbruck, Innsbruck 6020, Austria
| | - Anne Krogsdam
- Division of Bioinformatics, Biocenter, Medical University of Innsbruck, Innsbruck 6020, Austria
| | - Michael Rudnicki
- Department of Internal Medicine IV (Nephrology and Hypertension), Medical University of Innsbruck, Innsbruck 6020, Austria
| | - Gert Mayer
- Department of Internal Medicine IV (Nephrology and Hypertension), Medical University of Innsbruck, Innsbruck 6020, Austria
| | - Alexander Huettenhofer
- Division of Genomics and RNomics, Biocenter, Medical University of Innsbruck, Innsbruck 6020, Austria
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Meessen S, Najjar G, Azoitei A, Iben S, Bolenz C, Günes C. A Comparative Assessment of Replication Stress Markers in the Context of Telomerase. Cancers (Basel) 2022; 14:cancers14092205. [PMID: 35565334 PMCID: PMC9103842 DOI: 10.3390/cancers14092205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Accepted: 04/26/2022] [Indexed: 02/05/2023] Open
Abstract
Simple Summary Genetic alterations such as oncogenic- or aneuploidy-inducing mutations can induce replication stress as a tumor protection mechansim. Previous data indicated that telomerase may ameliorate the cellular responses that induce replication stress. However, the mechanisms how this may occur are still unclear. In order to address this question, the accurate evaluation of replication stress in the presence and absence of telomerase is crucial. Therefore, we used telomerase negative normal human fibroblasts, as well as their telomerase positive counterparts to compare the suitability of three protein markers (pRPA2, γ-H2AX and 53BP1), which were previously reported to accumulate in response to harmful conditions leading to replication stress in cells. In summary, we find that pRPA2 is the most consistent and reliable marker for the detection of replication stress. Further, we demonstrated that the inhibition of the DNA-damage activated ATM and ATR kinases by specific small compounds impaired the accumulation of pRPA2 foci in the absence of telomerase. These data suggest that telomerase rescues the cells from replication stress upon supression of DNA damage induction by modulating the ATM and ATR signaling pathways, and may therefore support tumor formation of genetically unstable cells. Abstract Aberrant replication stress (RS) is a source of genome instability and has serious implications for cell survival and tumourigenesis. Therefore, the detection of RS and the identification of the underlying molecular mechanisms are crucial for the understanding of tumourigenesis. Currently, three protein markers—p33-phosphorylated replication protein A2 (pRPA2), γ-phosphorylated H2AX (γ-H2AX), and Tumor Protein P53 Binding Protein 1 (53BP1)—are frequently used to detect RS. However, to our knowledge, there is no report that compares their suitability for the detection of different sources of RS. Therefore, in this study, we evaluate the suitability of pRPA2, γ-H2AX, and 53BP1 for the detection of RS caused by different sources of RS. In addition, we examine their suitability as markers of the telomerase-mediated alleviation of RS. For these purposes, we use here telomerase-negative human fibroblasts (BJ) and their telomerase-immortalized counterparts (BJ-hTERT). Replication stress was induced by the ectopic expression of the oncogenic RAS mutant RASG12V (OI-RS), by the knockdown of ploidy-control genes ORP3 or MAD2 (AI-RS), and by treatment with hydrogen peroxide (ROS-induced RS). The level of RS was determined by immunofluorescence staining for pRPA2, γ-H2AX, and 53BP1. Evaluation of the staining results revealed that pRPA2- and γ-H2AX provide a significant and reliable assessment of OI-RS and AI-RS compared to 53BP1. On the other hand, 53BP1 and pRPA2 proved to be superior to γ-H2AX for the evaluation of ROS-induced RS. Moreover, the data showed that among the tested markers, pRPA2 is best suited to evaluate the telomerase-mediated suppression of all three types of RS. In summary, the data indicate that the choice of marker is important for the evaluation of RS activated through different conditions.
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Affiliation(s)
- Sabine Meessen
- Department of Urology, Ulm University Hospital, 89081 Ulm, Germany; (S.M.); (G.N.); (A.A.); (C.B.)
| | - Gregoire Najjar
- Department of Urology, Ulm University Hospital, 89081 Ulm, Germany; (S.M.); (G.N.); (A.A.); (C.B.)
| | - Anca Azoitei
- Department of Urology, Ulm University Hospital, 89081 Ulm, Germany; (S.M.); (G.N.); (A.A.); (C.B.)
| | - Sebastian Iben
- Department of Dermatology, Ulm University Hospital, 89081 Ulm, Germany;
| | - Christian Bolenz
- Department of Urology, Ulm University Hospital, 89081 Ulm, Germany; (S.M.); (G.N.); (A.A.); (C.B.)
| | - Cagatay Günes
- Department of Urology, Ulm University Hospital, 89081 Ulm, Germany; (S.M.); (G.N.); (A.A.); (C.B.)
- Correspondence: ; Tel.: +49-(0)731-500-58019; Fax: +49-(0)731-500-58093
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3
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Hosseinzadeh A, Merikhian P, Naseri N, Eisavand MR, Farahmand L. MUC1 is a potential target to overcome trastuzumab resistance in breast cancer therapy. Cancer Cell Int 2022; 22:110. [PMID: 35248049 PMCID: PMC8897942 DOI: 10.1186/s12935-022-02523-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 02/12/2022] [Indexed: 02/07/2023] Open
Abstract
Although resistance is its major obstacle in cancer therapy, trastuzumab is the most successful agent in treating epidermal growth factor receptor 2 positive (HER2 +) breast cancer (BC). Some patients show resistance to trastuzumab, and scientists want to circumvent this problem. This review elaborately discusses possible resistance mechanisms to trastuzumab and introduces mucin 1 (MUC1) as a potential target efficient for overcoming such resistance. MUC1 belongs to the mucin family, playing the oncogenic/mitogenic roles in cancer cells and interacting with several other oncogenic receptors and pathways, such as HER2, β-catenin, NF-κB, and estrogen receptor (ERα). Besides, it has been established that MUC1- Cytoplasmic Domain (MUC1-CD) accelerates the development of resistance to trastuzumab and that silencing MUC1-C proto-oncogene is associated with increased sensitivity of HER2+ cells to trastuzumab-induced growth inhibitors. We mention why targeting MUC1 can be useful in overcoming trastuzumab resistance in cancer therapy.
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Houschyar KS, Borrelli MR, Rein S, Tapking C, Popp D, Puladi B, Ooms M, Schulz T, Maan ZN, Branski LK, Siemers F, Philipp-Dormston WG, Yazdi AS, Duscher D. Wnt ligand expression in malignant melanoma: new insights. EUROPEAN JOURNAL OF PLASTIC SURGERY 2022. [DOI: 10.1007/s00238-022-01941-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Kotiyal S, Evason KJ. Exploring the Interplay of Telomerase Reverse Transcriptase and β-Catenin in Hepatocellular Carcinoma. Cancers (Basel) 2021; 13:cancers13164202. [PMID: 34439356 PMCID: PMC8393605 DOI: 10.3390/cancers13164202] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2021] [Revised: 08/12/2021] [Accepted: 08/15/2021] [Indexed: 02/07/2023] Open
Abstract
Simple Summary Liver cancer is one of the deadliest human cancers. Two of the most common molecular aberrations in liver cancer are: (1) activating mutations in the gene encoding β-catenin (CTNNB1); and (2) promoter mutations in telomerase reverse transcriptase (TERT). Here, we review recent findings regarding the interplay between TERT and β-catenin in order to better understand their role in liver cancer. Abstract Hepatocellular carcinoma (HCC) is one of the deadliest human cancers. Activating mutations in the telomerase reverse transcriptase (TERT) promoter (TERTp) and CTNNB1 gene encoding β-catenin are widespread in HCC (~50% and ~30%, respectively). TERTp mutations are predicted to increase TERT transcription and telomerase activity. This review focuses on exploring the role of TERT and β-catenin in HCC and the current findings regarding their interplay. TERT can have contradictory effects on tumorigenesis via both its canonical and non-canonical functions. As a critical regulator of proliferation and differentiation in progenitor and stem cells, activated β-catenin drives HCC; however, inhibiting endogenous β-catenin can also have pro-tumor effects. Clinical studies revealed a significant concordance between TERTp and CTNNB1 mutations in HCC. In stem cells, TERT acts as a co-factor in β-catenin transcriptional complexes driving the expression of WNT/β-catenin target genes, and β-catenin can bind to the TERTp to drive its transcription. A few studies have examined potential interactions between TERT and β-catenin in HCC in vivo, and their results suggest that the coexpression of these two genes promotes hepatocarcinogenesis. Further studies are required with vertebrate models to better understand how TERT and β-catenin influence hepatocarcinogenesis.
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Xiang Y, Yu Y, Li Q, Jiang Z, Li J, Liang C, Chen J, Li Y, Chen X, Cao W. Mutual regulation between chicken telomerase reverse transcriptase and the Wnt/β-catenin signalling pathway inhibits apoptosis and promotes the replication of ALV-J in LMH cells. Vet Res 2021; 52:110. [PMID: 34412690 PMCID: PMC8375160 DOI: 10.1186/s13567-021-00979-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Accepted: 07/10/2021] [Indexed: 12/14/2022] Open
Abstract
This study aimed to explore the mutual regulation between chicken telomerase reverse transcriptase (chTERT) and the Wnt/β-catenin signalling pathway and its effects on cell growth and avian leukosis virus subgroup J (ALV-J) replication in LMH cells. First, LMH cells stably overexpressing the chTERT gene (LMH-chTERT cells) and corresponding control cells (LMH-NC cells) were successfully constructed with a lentiviral vector expression system. The results showed that chTERT upregulated the expression of β-catenin, Cyclin D1, TCF4 and c-Myc. chTERT expression level and telomerase activity were increased when cells were treated with LiCl. When the cells were treated with ICG001 or IWP-2, the activity of the Wnt/β-catenin signalling pathway was significantly inhibited, and chTERT expression and telomerase activity were also inhibited. However, when the β-catenin gene was knocked down by small interfering RNA (siRNA), the changes in chTERT expression and telomerase activity were consistent with those in cells treated with ICG001 or IWP-2. These results indicated that chTERT and the Wnt/β-catenin signalling pathway can be mutually regulated. Subsequently, we found that chTERT not only shortened the cell cycle to promote proliferation but also inhibited apoptosis by downregulating the expression of Caspase 3, Caspase 9 and BAX; upregulating BCL-2 and BCL-X expression; and promoting autophagy. Moreover, chTERT significantly enhanced the migration ability of LMH cells, upregulated the protein and mRNA expression of ALV-J and increased the virus titre. ALV-J replication promoted chTERT expression and telomerase activity.
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Affiliation(s)
- Yong Xiang
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, 510642, China
| | - Yun Yu
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, 510642, China
| | - Qingbo Li
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, 510642, China
| | - Zeng Jiang
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, 510642, China
| | - Jinqun Li
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, 510642, China
| | - Canxin Liang
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, 510642, China
| | - Jian Chen
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, 510642, China
| | - Yu Li
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, 510642, China
| | - Xiaoyan Chen
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, 510642, China
| | - Weisheng Cao
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, 510642, China. .,Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, South China Agricultural University, Guangzhou, 510642, China. .,Guangdong Laboratory for Lingnan Modern Agriculture, South China Agricultural University, Guangzhou, 510642, China. .,National and Regional Joint Engineering Laboratory for Medicament of Zoonosis Prevention and Control, South China Agricultural University, Guangzhou, 510642, China. .,Key Laboratory of Veterinary Vaccine Innovation of the Ministry of Agriculture, Guangzhou, 510642, China.
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7
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Telomerase Biogenesis and Activities from the Perspective of Its Direct Interacting Partners. Cancers (Basel) 2020; 12:cancers12061679. [PMID: 32599885 PMCID: PMC7352425 DOI: 10.3390/cancers12061679] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 06/20/2020] [Accepted: 06/22/2020] [Indexed: 12/15/2022] Open
Abstract
Telomerase reverse transcriptase (TERT)—the catalytic subunit of telomerase—is reactivated in up to 90% of all human cancers. TERT is observed in heterogenous populations of protein complexes, which are dynamically regulated in a cell type- and cell cycle-specific manner. Over the past two decades, in vitro protein–protein interaction detection methods have discovered a number of endogenous TERT binding partners in human cells that are responsible for the biogenesis and functionalization of the telomerase holoenzyme, including the processes of TERT trafficking between subcellular compartments, assembly into telomerase, and catalytic action at telomeres. Additionally, TERT have been found to interact with protein species with no known telomeric functions, suggesting that these complexes may contribute to non-canonical activities of TERT. Here, we survey TERT direct binding partners and discuss their contributions to TERT biogenesis and functions. The goal is to review the comprehensive spectrum of TERT pro-malignant activities, both telomeric and non-telomeric, which may explain the prevalence of its upregulation in cancer.
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9
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Thompson CA, Wong JM. Non-canonical Functions of Telomerase Reverse Transcriptase: Emerging Roles and Biological Relevance. Curr Top Med Chem 2020; 20:498-507. [DOI: 10.2174/1568026620666200131125110] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 01/10/2020] [Accepted: 01/21/2020] [Indexed: 12/11/2022]
Abstract
Increasing evidence from research on telomerase suggests that in addition to its catalytic telomere
repeat synthesis activity, telomerase may have other biologically important functions. The canonical
roles of telomerase are at the telomere ends where they elongate telomeres and maintain genomic
stability and cellular lifespan. The catalytic protein component Telomerase Reverse Transcriptase
(TERT) is preferentially expressed at high levels in cancer cells despite the existence of an alternative
mechanism for telomere maintenance (alternative lengthening of telomeres or ALT). TERT is also expressed
at higher levels than necessary for maintaining functional telomere length, suggesting other possible
adaptive functions. Emerging non-canonical roles of TERT include regulation of non-telomeric
DNA damage responses, promotion of cell growth and proliferation, acceleration of cell cycle kinetics,
and control of mitochondrial integrity following oxidative stress. Non-canonical activities of TERT primarily
show cellular protective effects, and nuclear TERT has been shown to protect against cell death
following double-stranded DNA damage, independent of its role in telomere length maintenance. TERT
has been suggested to act as a chromatin modulator and participate in the transcriptional regulation of
gene expression. TERT has also been reported to regulate transcript levels through an RNA-dependent
RNA Polymerase (RdRP) activity and produce siRNAs in a Dicer-dependent manner. At the mitochondria,
TERT is suggested to protect against oxidative stress-induced mtDNA damage and promote mitochondrial
integrity. These extra-telomeric functions of TERT may be advantageous in the context of increased
proliferation and metabolic stress often found in rapidly-dividing cancer cells. Understanding
the spectrum of non-canonical functions of telomerase may have important implications for the rational
design of anti-cancer chemotherapeutic drugs.
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Affiliation(s)
- Connor A.H. Thompson
- Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, V6T 1Z3, Canada
| | - Judy M.Y. Wong
- Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, V6T 1Z3, Canada
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10
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Wang S, Yan WW, He M, Wei D, Long ZJ, Tao YM. Aloe emodin inhibits telomerase activity in breast cancer cells: transcriptional and enzymological mechanism. Pharmacol Rep 2020; 72:1383-1396. [PMID: 32207090 DOI: 10.1007/s43440-020-00062-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2019] [Revised: 01/10/2020] [Accepted: 01/30/2020] [Indexed: 12/31/2022]
Abstract
BACKGROUND Telomerase plays an essential role in cancer cell proliferation. In this study, we investigated inhibition mechanism of aloe emodin (AE) on three different types of breast cancer cell lines, MDA-MB-453, MDA-MB-231 and MCF-7. METHODS The cells were treated with different concentrations of AE. Relative length of telomere and human telomerase reverse-transcriptase (hTERT) mRNA level was analyzed by quantitative PCR (qPCR). Protein level was assayed by Western blot. Sodium bisulfite methylation sequencing was performed to assess the methylation status of gene promoter. Enzymology kinetics was applied to reveal the interaction between AE and telomerase. Ultraviolet-visible titration and fluorescence resonance energy transfer (FRET) melting experiment were carried out to study the interaction between AE and telomeric DNA. RESULTS Continuous AE exposure of these cells for 48 h results in shortening of telomeres and inhibition of telomerase. The transcription of hTERT was repressed by activation of E2F1 and inactivation of c-myc proteins. Significant demethylation of CpG islands in hTERT gene promoter was observed in MDA-MB-453 and MCF-7 cells. AE competed with dNTP for occupation of the enzyme active site. AE was a telomeric G-quadruplex structure stabilizer as indicated by titration test and FRET experiments. CONCLUSIONS AE was a competitive inhibitor of telomerase and a G-quadruplex structure stabilizer. AE decreased the transcription of hTERT gene in the three breast cancer cell lines via up-regulation E2F1 and down-regulation c-myc expressions. The suppressed transcription was also related to the demethylation of the gene promoter.
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Affiliation(s)
- Song Wang
- College of Biotechnology, Guilin Medical University, Guilin, 541004, People's Republic of China.,Peking University Shenzhen Hospital, Shenzhen, 518035, People's Republic of China
| | - Wen-Wen Yan
- College of Biotechnology, Guilin Medical University, Guilin, 541004, People's Republic of China
| | - Min He
- College of Biotechnology, Guilin Medical University, Guilin, 541004, People's Republic of China
| | - Dan Wei
- College of Biotechnology, Guilin Medical University, Guilin, 541004, People's Republic of China
| | - Zu-Ji Long
- College of Biotechnology, Guilin Medical University, Guilin, 541004, People's Republic of China
| | - Yi-Ming Tao
- College of Biotechnology, Guilin Medical University, Guilin, 541004, People's Republic of China.
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Ségal-Bendirdjian E, Geli V. Non-canonical Roles of Telomerase: Unraveling the Imbroglio. Front Cell Dev Biol 2019; 7:332. [PMID: 31911897 PMCID: PMC6914764 DOI: 10.3389/fcell.2019.00332] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 11/27/2019] [Indexed: 12/11/2022] Open
Abstract
Telomerase plays a critical role in stem cell function and tissue regeneration that depends on its ability to elongate telomeres. For nearly two decades, it turned out that TERT regulates a broad spectrum of functions including signal transduction, gene expression regulation, and protection against oxidative damage that are independent of its telomere elongation activity. These conclusions that were mainly obtained in cell lines overexpressing telomerase were further strengthened by in vivo models of ectopic expression of telomerase or models of G1 TERT knockout mice without detectable telomere dysfunction. However, the later models were questioned due to the presence of aberrantly shortened telomere in the germline of the parents TERT+/- that were used to create the G1 TERT -/- mice. The physiological relevance of the functions associated with overexpressed telomerase raised also some concerns due to artifactual situations and localizations and complications to quantify the level of TERT. Another concern with non-canonical functions of TERT was the difficulty to separate a direct TERT-related function from secondary effects. Despite these concerns, more and more evidence accumulates for non-canonical roles of telomerase that are non-obligatory extra-telomeric. Here, we review these non-canonical roles of the TERT subunit of telomerase. Also, we emphasize recent results that link TERT to mitochondria and protection to reactive oxygen species suggesting a protective role of TERT in neurons. Throughout this review, we dissect some controversies regarding the non-canonical functions of telomerase and provide some insights to explain these discrepancies. Finally, we discuss the importance of understanding these alternative functions of telomerase for the development of anticancer strategies.
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Affiliation(s)
- Evelyne Ségal-Bendirdjian
- INSERM UMR-S 1124, Team: Cellular Homeostasis, Cancer and Therapies, INSERM US36, CNRS UMS 2009, BioMedTech Facilities, Université de Paris, Paris, France
| | - Vincent Geli
- Marseille Cancer Research Center, U1068 INSERM, UMR 7258 CNRS, Aix Marseille University, Institut Paoli-Calmettes, Equipe labellisée Ligue, Marseille, France
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12
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Günes C, Wezel F, Southgate J, Bolenz C. Implications of TERT promoter mutations and telomerase activity in urothelial carcinogenesis. Nat Rev Urol 2019; 15:386-393. [PMID: 29599449 DOI: 10.1038/s41585-018-0001-5] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Telomerase activity imparts eukaryotic cells with unlimited proliferation capacity, one of the cancer hallmarks. Over 90% of human urothelial carcinoma of the bladder (UCB) tumours are positive for telomerase activity. Telomerase activation can occur through several mechanisms. Mutations in the core promoter region of the human telomerase reverse transcriptase gene (TERT) cause telomerase reactivation in 60-80% of UCBs, whereas the prevalence of these mutations is lower in urothelial cancers of other origins. TERT promoter mutations are the most frequent genetic alteration across all stages of UCB, indicating a strong selection pressure during neoplastic transformation. TERT promoter mutations could arise during regeneration of normal urothelium and, owing to consequential telomerase reactivation, might be the basis of UCB initiation, which represents a new model of urothelial cancer origination. In the future, TERT promoter mutations and telomerase activity might have diagnostic and therapeutic applications in UCB.
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Affiliation(s)
- Cagatay Günes
- Department of Urology, University of Ulm, Ulm, Germany.
| | - Felix Wezel
- Department of Urology, University of Ulm, Ulm, Germany
| | - Jennifer Southgate
- Department of Biology, Jack Birch Unit of Molecular Carcinogenesis, University of York, York, UK
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De Meyer T, Nawrot T, Bekaert S, De Buyzere ML, Rietzschel ER, Andrés V. Telomere Length as Cardiovascular Aging Biomarker: JACC Review Topic of the Week. J Am Coll Cardiol 2019; 72:805-813. [PMID: 30092957 DOI: 10.1016/j.jacc.2018.06.014] [Citation(s) in RCA: 85] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 06/04/2018] [Accepted: 06/10/2018] [Indexed: 12/12/2022]
Abstract
Telomeres shorten with age, the major risk factor for atherosclerotic cardiovascular disease (aCVD). The observation of shorter telomeres in aCVD patients thus suggested that critical telomere shortening may contribute to premature biological aging and aCVD. Therefore, telomere length often is suggested as a causal aCVD risk factor, a proposal supported by recent Mendelian randomization studies; however, epidemiological research has shown disappointingly low effect sizes. It therefore remains uncertain whether telomere shortening is a cause of aCVD or merely a consequence. The authors argue that elucidating the mechanistic foundation of these findings is essential for any possible translation of telomere biology to the clinic. Here, they critically evaluate evidence for causality in animal models and human studies, and review popular hypotheses and discuss their clinical implications. The authors identify 4 key questions that any successful mechanistic theory should address, and they discuss how atherosclerosis-associated local telomere attrition may provide the answers.
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Affiliation(s)
- Tim De Meyer
- Department of Data Analysis and Mathematical Modelling, Ghent University, Belgium.
| | - Tim Nawrot
- Centre for Environmental Sciences, Hasselt University, Hasselt, Belgium
| | - Sofie Bekaert
- Bimetra Clinical Research Center, Ghent University Hospital, Ghent, Belgium
| | - Marc L De Buyzere
- Department of Cardiovascular Diseases, Ghent University, Ghent, Belgium
| | | | - Vicente Andrés
- Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain; CIBER de Enfermedades Cardiovasculares (CIBER-CV), Madrid, Spain
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Fernandez RJ, Johnson FB. A regulatory loop connecting WNT signaling and telomere capping: possible therapeutic implications for dyskeratosis congenita. Ann N Y Acad Sci 2019; 1418:56-68. [PMID: 29722029 DOI: 10.1111/nyas.13692] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 03/02/2018] [Accepted: 03/04/2018] [Indexed: 12/15/2022]
Abstract
The consequences of telomere dysfunction are most apparent in rare inherited syndromes caused by genetic deficiencies in factors that normally maintain telomeres. The principal disease is known as dyskeratosis congenita (DC), but other syndromes with similar underlying genetic defects share some clinical aspects with this disease. Currently, there are no curative therapies for these diseases of telomere dysfunction. Here, we review recent findings demonstrating that dysfunctional (i.e., uncapped) telomeres can downregulate the WNT pathway, and that restoration of WNT signaling helps to recap telomeres by increasing expression of shelterins, proteins that naturally bind and protect telomeres. We discuss how these findings are different from previous observations connecting WNT and telomere biology, and discuss potential links between WNT and clinical manifestations of the DC spectrum of diseases. Finally, we argue for exploring the use of WNT agonists, specifically lithium, as a possible therapeutic approach for patients with DC.
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Affiliation(s)
- Rafael Jesus Fernandez
- Cell and Molecular Biology Program, Biomedical Graduate Studies, Medical Scientist Training Program, Philadelphia, Pennsylvania.,Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - F Brad Johnson
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
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15
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Ravi M, Sneka MK, Joshipura A. The culture conditions and outputs from breast cancer cell line in vitro experiments. Exp Cell Res 2019; 383:111548. [PMID: 31398351 DOI: 10.1016/j.yexcr.2019.111548] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 08/02/2019] [Accepted: 08/03/2019] [Indexed: 10/26/2022]
Abstract
One of the major cancer types that have gained significant importance globally is the breast cancer due to its socio-economic impact. Breast cancer research is an area of considerable importance and several types of material are available for research applications. These include cancer cell lines which can be utilized in several ways. Cell lines are convenient to use and recently about 84 human breast cancer cell lines were classified by molecular sub-typing. These cells lines come under five major molecular subtypes namely the luminal A and B, HER-2+, triple- A and B subtypes. These cell lines have been well characterized and were utilized for understanding various aspects of breast cancers. Also, apart from providing an understanding of the molecular mechanisms associated with breast cancers, these cell lines have contributed significantly to areas such as drug testing. We present in this review the features of these cell lines, the studies conducted using them and the outcome of such studies. Also, the details about the culture conditions and study outcomes of the cell lines grown in 3-dimensional (3D) systems are presented.
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Affiliation(s)
- Maddaly Ravi
- Department of Human Genetics, Faculty of Biomedical Sciences, Technology and Research, Sri Ramachandra Institute of Higher Education and Research, Porur, Chennai, 600116, India.
| | - M Kaviya Sneka
- Department of Human Genetics, Faculty of Biomedical Sciences, Technology and Research, Sri Ramachandra Institute of Higher Education and Research, Porur, Chennai, 600116, India
| | - Aastha Joshipura
- Department of Human Genetics, Faculty of Biomedical Sciences, Technology and Research, Sri Ramachandra Institute of Higher Education and Research, Porur, Chennai, 600116, India
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16
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Yuan X, Xu D. Telomerase Reverse Transcriptase (TERT) in Action: Cross-Talking with Epigenetics. Int J Mol Sci 2019; 20:ijms20133338. [PMID: 31284662 PMCID: PMC6651578 DOI: 10.3390/ijms20133338] [Citation(s) in RCA: 39] [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: 06/18/2019] [Revised: 07/01/2019] [Accepted: 07/04/2019] [Indexed: 02/07/2023] Open
Abstract
Telomerase, an RNA-dependent DNA polymerase with telomerase reverse transcriptase (TERT) as the catalytic component, is silent due to the tight repression of the TERT gene in most normal human somatic cells, whereas activated only in small subsets of cells, including stem cells, activated lymphocytes, and other highly proliferative cells. In contrast, telomerase activation via TERT induction is widespread in human malignant cells, which is a prerequisite for malignant transformation. It is well established that TERT/telomerase extends telomere length, thereby conferring sustained proliferation capacity to both normal and cancerous cells. The recent evidence has also accumulated that TERT/telomerase may participate in the physiological process and oncogenesis independently of its telomere-lengthening function. For instance, TERT is shown to interact with chromatin remodeling factors and to regulate DNA methylation, through which multiple cellular functions are attained. In the present review article, we summarize the non-canonical functions of TERT with a special emphasis on its cross-talk with epigenetics: How TERT contributes to epigenetic alterations in physiological processes and cancer, and how the aberrant epigenetics in turn facilitate TERT expression and function, eventually promoting cancer either initiation or progression or both. Finally, we briefly discuss clinical implications of the TERT-related methylation.
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Affiliation(s)
- Xiaotian Yuan
- School of Medicine, Shandong University, Jinan 250012, China.
- Department of Medicine, Center for Molecular Medicine (CMM) and Bioclinicum, Karolinska Institute and Karolinska University Hospital Solna, 171 64 Solna, Sweden.
| | - Dawei Xu
- Department of Medicine, Center for Molecular Medicine (CMM) and Bioclinicum, Karolinska Institute and Karolinska University Hospital Solna, 171 64 Solna, Sweden.
- Shandong University-Karolinska Institute Collaborative Laboratory for Cancer and Stem Cell Research, Jinan 250033, China.
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17
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de Punder K, Heim C, Wadhwa PD, Entringer S. Stress and immunosenescence: The role of telomerase. Psychoneuroendocrinology 2019; 101:87-100. [PMID: 30445409 PMCID: PMC6458519 DOI: 10.1016/j.psyneuen.2018.10.019] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 09/27/2018] [Accepted: 10/22/2018] [Indexed: 01/04/2023]
Abstract
Chronic stress is associated with the accelerated aging of the immune system and represents a potent risk factor for the development and progression of a wide range of physical and mental disorders. The elucidation of molecular pathways and mechanisms underlying the link between stress and cellular aging is an area of considerable interest and investigation. In this context, telomere biology has emerged as a particularly attractive candidate mechanism. Several studies have linked immune cell telomere length with stress-related conditions and states, and also with several physical and mental disorders. Because the cellular reverse transcriptase enzyme telomerase is the primary regulator of telomere length (by adding telomeric DNA to telomeres and thereby attenuating telomere shortening), the understanding of its regulation and regulatory functions constitutes a prime target for developing strategies to prevent, attenuate or reverse the adverse consequences of immune system aging (immunosenescence). In this review we provide an overview of the mechanistic pathways linking telomerase with stress and cellular aging, with an emphasis on the immune system. We summarize and synthesize the current state of the literature on immune cell telomerase in different stress- and aging-related disease states and provide recommendations for future research directions.
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Affiliation(s)
- Karin de Punder
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health (BIH), Institute of Medical Psychology, Berlin, Germany.
| | - Christine Heim
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health (BIH), Institute of Medical Psychology, Berlin, Germany; Department of Biobehavioral Health, College of Health and Human Development, Pennsylvania State University, USA
| | - Pathik D Wadhwa
- Department of Psychiatry & Human Behavior, University of California, Irvine, School of Medicine, Irvine, CA, USA; Department of Obstetrics & Gynecology, University of California, Irvine, School of Medicine, Irvine, CA, USA; Department of Pediatrics, University of California, Irvine, School of Medicine, Irvine, CA, USA; Department of Epidemiology, University of California, Irvine, School of Medicine, Irvine, CA, USA
| | - Sonja Entringer
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health (BIH), Institute of Medical Psychology, Berlin, Germany; Department of Pediatrics, University of California, Irvine, School of Medicine, Irvine, CA, USA; Development, Health and Disease Research Program, University of California, Irvine, School of Medicine, Irvine, CA, USA
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18
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Romaniuk A, Paszel-Jaworska A, Totoń E, Lisiak N, Hołysz H, Królak A, Grodecka-Gazdecka S, Rubiś B. The non-canonical functions of telomerase: to turn off or not to turn off. Mol Biol Rep 2018; 46:1401-1411. [PMID: 30448892 DOI: 10.1007/s11033-018-4496-x] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Accepted: 11/12/2018] [Indexed: 12/19/2022]
Abstract
Telomerase is perceived as an immortality enzyme that enables passing the Hayflick limit. Its main function is telomere restoration but only in a limited group of cells, including cancer cells. Since it is found in a vast majority of cancer cells, it became a natural target for cancer therapy. However, it has much more functions than just altering the metabolism of telomeres-it also reveals numerous so-called non-canonical functions. Thus, a question arises whether it is always beneficial to turn it off when planning a cancer strategy and considering potential side effects? The purpose of this review is to discuss some of the recent discoveries about telomere-independent functions of telomerase in the context of cancer therapy and potential side effects.
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Affiliation(s)
- Aleksandra Romaniuk
- Department of Clinical Chemistry and Molecular Diagnostics, Poznan University of Medical Sciences, 49 Przybyszewskiego St., 60-355, Poznań, Poland
| | - Anna Paszel-Jaworska
- Department of Clinical Chemistry and Molecular Diagnostics, Poznan University of Medical Sciences, 49 Przybyszewskiego St., 60-355, Poznań, Poland
| | - Ewa Totoń
- Department of Clinical Chemistry and Molecular Diagnostics, Poznan University of Medical Sciences, 49 Przybyszewskiego St., 60-355, Poznań, Poland
| | - Natalia Lisiak
- Department of Clinical Chemistry and Molecular Diagnostics, Poznan University of Medical Sciences, 49 Przybyszewskiego St., 60-355, Poznań, Poland
| | - Hanna Hołysz
- Department of Clinical Chemistry and Molecular Diagnostics, Poznan University of Medical Sciences, 49 Przybyszewskiego St., 60-355, Poznań, Poland
| | - Anna Królak
- Department of Clinical Chemistry and Molecular Diagnostics, Poznan University of Medical Sciences, 49 Przybyszewskiego St., 60-355, Poznań, Poland
| | | | - Błażej Rubiś
- Department of Clinical Chemistry and Molecular Diagnostics, Poznan University of Medical Sciences, 49 Przybyszewskiego St., 60-355, Poznań, Poland.
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19
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Abstract
PURPOSE OF REVIEW High-throughput genomic sequencing has identified alterations in the gene encoding human telomerase reverse transcriptase (TERT) as points of interest for elucidating the oncogenic mechanism of multiple different cancer types, including gliomas. In gliomas, the TERT promoter mutation (TPM) and resultant overexpression of TERT are observed mainly in the most aggressive (primary glioblastoma/grade IV astrocytoma) and the least aggressive (grade II oligodendroglioma) cases. This article reviews recent research on (1) the mechanism of TERT activation in glioma, (2) downstream consequences of TERT overexpression on glioma pathogenesis, and (3) targeting TPMs as a therapeutic strategy. RECENT FINDINGS New molecular classifications for gliomas include using TPMs, where the mutant group demonstrates the worst prognosis. Though a canonical function of TERT is established in regard to telomere maintenance, recent studies on non-canonical functions of TERT explore varied roles of telomerase in tumor progression and maintenance. Somatic alterations of the TERT promoter present a promising target for novel therapeutics development in primary glioma treatment.
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20
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Hapangama DK, Kamal A, Saretzki G. Implications of telomeres and telomerase in endometrial pathology. Hum Reprod Update 2017; 23:166-187. [PMID: 27979878 PMCID: PMC5850744 DOI: 10.1093/humupd/dmw044] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 12/02/2016] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Eukaryotic chromosomal ends are linear and are protected by nucleoprotein complexes known as telomeres. The complex structural anatomy and the diverse functions of telomeres as well as the unique reverse transcriptase enzyme, telomerase that maintains telomeres are under intensive scientific scrutiny. Both are involved in many human diseases including cancer, but also in ageing and chronic disease such as diabetes. Their intricate involvement in many cellular processes and pathways is being dynamically deciphered in many organs including the endometrium. This review summarizes our current knowledge on the topic of telomeres and telomerase and their potential role in providing plausible explanations for endometrial aberrations related to common gynaecological pathologies. OBJECTIVE AND RATIONALE This review outlines the recent major findings in telomere and telomerase functions in the context of endometrial biology. It highlights the contemporary discoveries in hormonal regulation, normal endometrial regeneration, stem cells and common gynaecological diseases such as endometriosis, infertility, recurrent reproductive failure and endometrial cancer (EC). SEARCH METHODS The authors carried out systematic PubMed (Medline) and Ovid searches using the key words: telomerase, telomeres, telomere length, human telomerase reverse transcriptase, telomeric RNA component, with endometrium, hormonal regulation, endometrial stem/progenitor cells, endometrial regeneration, endometriosis, recurrent miscarriage, infertility, endometrial hyperplasia, EC and uterine cancer. Publications used in this review date from 1995 until 31st June 2016. OUTCOMES The human endometrium is a unique somatic organ, which displays dynamic telomerase activity (TA) related to the menstrual cycle. Telomerase is implicated in almost all endometrial pathologies and appears to be crucial to endometrial stem cells. In particular, it is vital for normal endometrial regeneration, providing a distinct route to formulate possible curative, non-hormonal therapies to treat chronic endometrial conditions. Furthermore, our current understanding of telomere maintenance in EC is incomplete. Data derived from other malignancies on the role of telomerase in carcinogenesis cannot be extrapolated to EC because unlike in other cancers, TA is already present in proliferating healthy endometrial cells. WIDER IMPLICATIONS Since telomerase is pivotal to endometrial regeneration, further studies elucidating the role of telomeres, telomerase, their associated proteins and their regulation in normal endometrial regeneration as well as their role in endometrial pathologies are essential. This approach may allow future development of novel treatment strategies that are not only non-hormonal but also potentially curative.
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Affiliation(s)
- D K Hapangama
- Department of Women's and Children's Health, Institute of Translational Medicine, University of Liverpool, Liverpool, L8 7SS, UK.,Liverpool Women's Hospital NHS Foundation Trust, Crown Street, Liverpool L8 7SS, UK
| | - A Kamal
- Department of Women's and Children's Health, Institute of Translational Medicine, University of Liverpool, Liverpool, L8 7SS, UK.,The National Center for Early Detection of Cancer, Oncology Teaching Hospital, Baghdad Medical City, Baghdad, Iraq
| | - G Saretzki
- Institute for Ageing and Institute for Cell and Molecular Biosciences, Campus for Ageing and Vitality, Newcastle University, Newcastle upon Tyne, NE4 5PL, UK
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21
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Mutual reinforcement between telomere capping and canonical Wnt signalling in the intestinal stem cell niche. Nat Commun 2017; 8:14766. [PMID: 28303901 PMCID: PMC5357864 DOI: 10.1038/ncomms14766] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Accepted: 01/27/2017] [Indexed: 12/30/2022] Open
Abstract
Critical telomere shortening (for example, secondary to partial telomerase deficiency in the rare disease dyskeratosis congenita) causes tissue pathology, but underlying mechanisms are not fully understood. Mice lacking telomerase (for example, mTR−/− telomerase RNA template mutants) provide a model for investigating pathogenesis. In such mice, after several generations of telomerase deficiency telomeres shorten to the point of uncapping, causing defects most pronounced in high-turnover tissues including intestinal epithelium. Here we show that late-generation mTR−/− mutants experience marked downregulation of Wnt pathway genes in intestinal crypt epithelia, including crypt base columnar stem cells and Paneth cells, and in underlying stroma. The importance of these changes was revealed by rescue of crypt apoptosis and Wnt pathway gene expression upon treatment with Wnt pathway agonists. Rescue was associated with reduced telomere-dysfunction-induced foci and anaphase bridges, indicating improved telomere capping. Thus a mutually reinforcing feedback loop exists between telomere capping and Wnt signalling, and telomere capping can be impacted by extracellular cues in a fashion independent of telomerase. Mice lacking telomerase provide a model to study pathogenesis caused by critical telomere shortening. Here, the authors provide evidence that telomere shortening causes downregulation of Wnt signalling in intestinal crypts and that defects can be partially rescued by treatment with Wnt agonists.
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22
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Pestana A, Vinagre J, Sobrinho-Simões M, Soares P. TERT biology and function in cancer: beyond immortalisation. J Mol Endocrinol 2017; 58:R129-R146. [PMID: 28057768 DOI: 10.1530/jme-16-0195] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 01/05/2017] [Indexed: 12/23/2022]
Abstract
Evasion of replicative senescence and proliferation without restriction, sometimes designated as immortalisation, is one of the hallmarks of cancer that may be attained through reactivation of telomerase in somatic cells. In contrast to most normal cells in which there is lack of telomerase activity, upregulation of TERT transcription/activity is detected in 80-90% of malignant tumours. In several types of cancer, there is a relationship between the presence of TERT promoter mutations, TERT mRNA expression and clinicopathological features, but the biological bridge between the occurrence of TERT promoter mutations and the aggressive/invasive features displayed by the tumours remains unidentified. We and others have associated the presence of TERT promoter mutations with metastisation/survival in several types of cancer. In follicular cell-derived thyroid cancer, such mutations are associated with worse prognostic features (age of patients, tumour size and tumour stage) as well as with distant metastases, worse response to treatment and poorer survival. In this review, we analyse the data reported in several studies that imply TERT transcription reactivation/activity with cell proliferation, tumour invasion and metastisation. A particular attention is given to the putative connections between TERT transcriptional reactivation and signalling pathways frequently altered in cancer, such as c-MYC, NF-κB and B-Catenin.
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Affiliation(s)
- Ana Pestana
- Institute of Molecular Pathology and ImmunologyUniversity of Porto (IPATIMUP), Porto, Portugal
- Institute for Research and Innovation in Health (I3S)University of Porto, Porto, Portugal
| | - João Vinagre
- Institute of Molecular Pathology and ImmunologyUniversity of Porto (IPATIMUP), Porto, Portugal
- Institute for Research and Innovation in Health (I3S)University of Porto, Porto, Portugal
| | - Manuel Sobrinho-Simões
- Institute of Molecular Pathology and ImmunologyUniversity of Porto (IPATIMUP), Porto, Portugal
- Institute for Research and Innovation in Health (I3S)University of Porto, Porto, Portugal
- Medical FacultyUniversity of Porto, Porto, Portugal
- Department of PathologyCentro Hospitalar S. João, Porto, Portugal
- Department of PathologyMedical Faculty, University of Porto, Porto, Portugal
| | - Paula Soares
- Institute of Molecular Pathology and ImmunologyUniversity of Porto (IPATIMUP), Porto, Portugal
- Institute for Research and Innovation in Health (I3S)University of Porto, Porto, Portugal
- Medical FacultyUniversity of Porto, Porto, Portugal
- Department of PathologyMedical Faculty, University of Porto, Porto, Portugal
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23
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Abstract
Telomerase activity is responsible for the maintenance of chromosome end structures (telomeres) and cancer cell immortality in most human malignancies, making telomerase an attractive therapeutic target. The rationale for targeting components of the telomerase holoenzyme has been strengthened by accumulating evidence indicating that these molecules have extra-telomeric functions in tumour cell survival and proliferation. This Review discusses current knowledge of the biogenesis, structure and multiple functions of telomerase-associated molecules intertwined with recent advances in drug discovery approaches. We also describe the fertile ground available for the pursuit of next-generation small-molecule inhibitors of telomerase.
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Affiliation(s)
- Greg M Arndt
- Australian Cancer Research Foundation (ACRF) Drug Discovery Centre for Childhood Cancer, Children's Cancer Institute Australia, Lowy Cancer Research Centre, University of New South Wales, Randwick, New South Wales 2031, Australia
| | - Karen L MacKenzie
- Personalised Medicine Program, Children's Cancer Institute Australia, Lowy Cancer Research Centre, University of New South Wales, Randwick, New South Wales 2031, Australia
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24
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Liu H, Liu Q, Ge Y, Zhao Q, Zheng X, Zhao Y. hTERT promotes cell adhesion and migration independent of telomerase activity. Sci Rep 2016; 6:22886. [PMID: 26971878 PMCID: PMC4789728 DOI: 10.1038/srep22886] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Accepted: 02/23/2016] [Indexed: 02/07/2023] Open
Abstract
hTERT, a catalytic component of human telomerase, is undetectable in normal somatic cells but up-regulated in cancer and stem cells where telomere length is maintained by telomerase. Accumulated evidence indicates that hTERT may have noncanonical functions beyond telomerase by regulating the expression of particular genes. However, comprehensive identification of the genes regulated by hTERT is unavailable. In this report, we expressed WT hTERT and hTERTmut which displays dysfunctional catalytic activity, in human U2OS cancer cells and VA-13 immortalized fibroblast cells, both of which lack endogenous hTERT and hTR expression. Changes in gene expression induced by hTERT and hTERT-mut expression were determined by genome-wide RNA-seq and verified by qPCR. Our results showed that hTERT affects different genes in two cell lines, implying that the regulation of gene expression by hTERT is indirect and cell type dependent. Moreover, functional analysis identifies cell adhesion-related genes that have been changed by hTERT in both cell lines. Adhesion experiments revealed that hTERT expression significantly increases cell adhesion. Monolayer wound healing and transwell assays demonstrated increased cell migration upon hTERT expression. These results provide new evidence to support a noncanonical function for hTERT in promoting tumorigenesis.
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Affiliation(s)
- Haiying Liu
- Key Laboratory of Gene Engineering of the Ministry of Education, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006 P. R. China.,Collaborative Innovation Center of High Performance Computing, National University of Defense Technology, Changsha 410073, P. R. China
| | - Qianqian Liu
- Key Laboratory of Gene Engineering of the Ministry of Education, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006 P. R. China.,Collaborative Innovation Center of High Performance Computing, National University of Defense Technology, Changsha 410073, P. R. China
| | - Yuanlong Ge
- Key Laboratory of Gene Engineering of the Ministry of Education, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006 P. R. China.,Collaborative Innovation Center of High Performance Computing, National University of Defense Technology, Changsha 410073, P. R. China
| | - Qi Zhao
- Key Laboratory of Gene Engineering of the Ministry of Education, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006 P. R. China
| | - Xiaohui Zheng
- Key Laboratory of Gene Engineering of the Ministry of Education, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006 P. R. China.,Collaborative Innovation Center of High Performance Computing, National University of Defense Technology, Changsha 410073, P. R. China
| | - Yong Zhao
- Key Laboratory of Gene Engineering of the Ministry of Education, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006 P. R. China.,Collaborative Innovation Center of High Performance Computing, National University of Defense Technology, Changsha 410073, P. R. China
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25
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Hong J, Lee JH, Chung IK. Telomerase activates transcription of cyclin D1 gene through an interaction with NOL1. J Cell Sci 2016; 129:1566-79. [PMID: 26906424 DOI: 10.1242/jcs.181040] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Accepted: 02/15/2016] [Indexed: 12/28/2022] Open
Abstract
Telomerase is a ribonucleoprotein enzyme that is required for the maintenance of telomere repeats. Although overexpression of telomerase in normal human somatic cells is sufficient to overcome replicative senescence, the ability of telomerase to promote tumorigenesis requires additional activities that are independent of its role in telomere extension. Here, we identify proliferation-associated nucleolar antigen 120 (NOL1, also known as NOP2) as a telomerase RNA component (TERC)-binding protein that is found in association with catalytically active telomerase. Although NOL1 is highly expressed in the majority of human tumor cells, the molecular mechanism by which NOL1 contributes to tumorigenesis remained unclear. We show that NOL1 binds to the T-cell factor (TCF)-binding element of the cyclin D1 promoter and activates its transcription. Interestingly, telomerase is also recruited to the cyclin D1 promoter in a TERC-dependent manner through the interaction with NOL1, further enhancing transcription of the cyclin D1 gene. Depletion of NOL1 suppresses cyclin D1 promoter activity, thereby leading to induction of growth arrest and altered cell cycle distributions. Collectively, our findings suggest that NOL1 represents a new route by which telomerase activates transcription of cyclin D1 gene, thus maintaining cell proliferation capacity.
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Affiliation(s)
- Juyeong Hong
- Department of Integrated Omics for Biomedical Science, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
| | - Ji Hoon Lee
- Department of Integrated Omics for Biomedical Science, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
| | - In Kwon Chung
- Department of Integrated Omics for Biomedical Science, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
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26
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New surprises from an old favourite: The emergence of telomerase as a key player in the regulation of cancer stemness. Biochimie 2016; 121:170-8. [DOI: 10.1016/j.biochi.2015.12.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 12/09/2015] [Indexed: 12/30/2022]
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27
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Teichroeb JH, Kim J, Betts DH. The role of telomeres and telomerase reverse transcriptase isoforms in pluripotency induction and maintenance. RNA Biol 2016; 13:707-19. [PMID: 26786236 DOI: 10.1080/15476286.2015.1134413] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Telomeres are linear guanine-rich DNA structures at the ends of chromosomes. The length of telomeric DNA is actively regulated by a number of mechanisms in highly proliferative cells such as germ cells, cancer cells, and pluripotent stem cells. Telomeric DNA is synthesized by way of the ribonucleoprotein called telomerase containing a reverse transcriptase (TERT) subunit and RNA component (TERC). TERT is highly conserved across species and ubiquitously present in their respective pluripotent cells. Recent studies have uncovered intricate associations between telomeres and the self-renewal and differentiation properties of pluripotent stem cells. Interestingly, the past decade's work indicates that the TERT subunit also has the capacity to modulate mitochondrial function, to remodel chromatin structure, and to participate in key signaling pathways such as the Wnt/β-catenin pathway. Many of these non-canonical functions do not require TERT's catalytic activity, which hints at possible functions for the extensive number of alternatively spliced TERT isoforms that are highly expressed in pluripotent stem cells. In this review, some of the established and potential routes of pluripotency induction and maintenance are highlighted from the perspectives of telomere maintenance, known TERT isoform functions and their complex regulation.
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Affiliation(s)
- Jonathan H Teichroeb
- a Department of Physiology and Pharmacology, Schulich School of Medicine & Dentistry , The University of Western Ontario , London , Ontario , Canada
| | - Joohwan Kim
- a Department of Physiology and Pharmacology, Schulich School of Medicine & Dentistry , The University of Western Ontario , London , Ontario , Canada
| | - Dean H Betts
- a Department of Physiology and Pharmacology, Schulich School of Medicine & Dentistry , The University of Western Ontario , London , Ontario , Canada.,b Children's Health Research Institute, Lawson Health Research Institute , London , Ontario , Canada
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Feitelson MA, Arzumanyan A, Kulathinal RJ, Blain SW, Holcombe RF, Mahajna J, Marino M, Martinez-Chantar ML, Nawroth R, Sanchez-Garcia I, Sharma D, Saxena NK, Singh N, Vlachostergios PJ, Guo S, Honoki K, Fujii H, Georgakilas AG, Bilsland A, Amedei A, Niccolai E, Amin A, Ashraf SS, Boosani CS, Guha G, Ciriolo MR, Aquilano K, Chen S, Mohammed SI, Azmi AS, Bhakta D, Halicka D, Keith WN, Nowsheen S. Sustained proliferation in cancer: Mechanisms and novel therapeutic targets. Semin Cancer Biol 2015; 35 Suppl:S25-S54. [PMID: 25892662 PMCID: PMC4898971 DOI: 10.1016/j.semcancer.2015.02.006] [Citation(s) in RCA: 432] [Impact Index Per Article: 48.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 02/20/2015] [Accepted: 02/23/2015] [Indexed: 02/08/2023]
Abstract
Proliferation is an important part of cancer development and progression. This is manifest by altered expression and/or activity of cell cycle related proteins. Constitutive activation of many signal transduction pathways also stimulates cell growth. Early steps in tumor development are associated with a fibrogenic response and the development of a hypoxic environment which favors the survival and proliferation of cancer stem cells. Part of the survival strategy of cancer stem cells may manifested by alterations in cell metabolism. Once tumors appear, growth and metastasis may be supported by overproduction of appropriate hormones (in hormonally dependent cancers), by promoting angiogenesis, by undergoing epithelial to mesenchymal transition, by triggering autophagy, and by taking cues from surrounding stromal cells. A number of natural compounds (e.g., curcumin, resveratrol, indole-3-carbinol, brassinin, sulforaphane, epigallocatechin-3-gallate, genistein, ellagitannins, lycopene and quercetin) have been found to inhibit one or more pathways that contribute to proliferation (e.g., hypoxia inducible factor 1, nuclear factor kappa B, phosphoinositide 3 kinase/Akt, insulin-like growth factor receptor 1, Wnt, cell cycle associated proteins, as well as androgen and estrogen receptor signaling). These data, in combination with bioinformatics analyses, will be very important for identifying signaling pathways and molecular targets that may provide early diagnostic markers and/or critical targets for the development of new drugs or drug combinations that block tumor formation and progression.
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Affiliation(s)
- Mark A Feitelson
- Department of Biology, Temple University, Philadelphia, PA, United States.
| | - Alla Arzumanyan
- Department of Biology, Temple University, Philadelphia, PA, United States
| | - Rob J Kulathinal
- Department of Biology, Temple University, Philadelphia, PA, United States
| | - Stacy W Blain
- Department of Pediatrics, State University of New York, Downstate Medical Center, Brooklyn, NY, United States
| | - Randall F Holcombe
- Tisch Cancer Institute, Mount Sinai School of Medicine, New York, NY, United States
| | - Jamal Mahajna
- MIGAL-Galilee Technology Center, Cancer Drug Discovery Program, Kiryat Shmona, Israel
| | - Maria Marino
- Department of Science, University Roma Tre, V.le G. Marconi, 446, 00146 Rome, Italy
| | - Maria L Martinez-Chantar
- Metabolomic Unit, CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas, Technology Park of Bizkaia, Bizkaia, Spain
| | - Roman Nawroth
- Department of Urology, Klinikum rechts der Isar der Technischen Universität München, Munich, Germany
| | - Isidro Sanchez-Garcia
- Experimental Therapeutics and Translational Oncology Program, Instituto de Biología Molecular y Celular del Cáncer, CSIC/Universidad de Salamanca, Salamanca, Spain
| | - Dipali Sharma
- Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Neeraj K Saxena
- Department of Oncology, Johns Hopkins University School of Medicine and the Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD, United States
| | - Neetu Singh
- Tissue and Cell Culture Unit, CSIR-Central Drug Research Institute, Council of Scientific & Industrial Research, Lucknow, India
| | | | - Shanchun Guo
- Department of Microbiology, Biochemistry & Immunology, Morehouse School of Medicine, Atlanta, GA, United States
| | - Kanya Honoki
- Department of Orthopedic Surgery, Nara Medical University, Kashihara 634-8521, Japan
| | - Hiromasa Fujii
- Department of Orthopedic Surgery, Nara Medical University, Kashihara 634-8521, Japan
| | - Alexandros G Georgakilas
- Physics Department, School of Applied Mathematical and Physical Sciences, National Technical University of Athens, Zografou 15780, Athens, Greece
| | - Alan Bilsland
- Institute of Cancer Sciences, University of Glasgow, UK
| | - Amedeo Amedei
- Department of Experimental and Clinical Medicine, University of Florence, 50134 Florence, Italy
| | - Elena Niccolai
- Department of Experimental and Clinical Medicine, University of Florence, 50134 Florence, Italy
| | - Amr Amin
- Department of Biology, College of Science, UAE University, Al-Ain, United Arab Emirates
| | - S Salman Ashraf
- Department of Chemistry, College of Science, UAE University, Al-Ain, United Arab Emirates
| | - Chandra S Boosani
- Department of BioMedical Sciences, Creighton University, Omaha, NE, United States
| | - Gunjan Guha
- School of Chemical and Bio Technology, SASTRA University, Thanjavur, India
| | - Maria Rosa Ciriolo
- Department of Biology, University of Rome "Tor Vergata", 00133 Rome, Italy
| | - Katia Aquilano
- Department of Biology, University of Rome "Tor Vergata", 00133 Rome, Italy
| | - Sophie Chen
- Department of Research and Development, Ovarian and Prostate Cancer Research Trust Laboratory, Guildford, Surrey GU2 7YG, United Kingdom
| | - Sulma I Mohammed
- Department of Comparative Pathobiology, Purdue University Center for Cancer Research, West Lafayette, IN, United States
| | - Asfar S Azmi
- Department of Pathology, Karmonas Cancer Institute, Wayne State University School of Medicine, Detroit, MI, United States
| | - Dipita Bhakta
- School of Chemical and Bio Technology, SASTRA University, Thanjavur, India
| | - Dorota Halicka
- Brander Cancer Research Institute, Department of Pathology, New York Medical College, Valhalla, NY, United States
| | - W Nicol Keith
- Institute of Cancer Sciences, University of Glasgow, UK
| | - Somaira Nowsheen
- Mayo Graduate School, Mayo Medical School, Mayo Clinic Medical Scientist Training Program, Rochester, MN, United States
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Sishc BJ, Nelson CB, McKenna MJ, Battaglia CLR, Herndon A, Idate R, Liber HL, Bailey SM. Telomeres and Telomerase in the Radiation Response: Implications for Instability, Reprograming, and Carcinogenesis. Front Oncol 2015; 5:257. [PMID: 26636039 PMCID: PMC4656829 DOI: 10.3389/fonc.2015.00257] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 11/06/2015] [Indexed: 01/06/2023] Open
Abstract
Telomeres are nucleoprotein complexes comprised of tandem arrays of repetitive DNA sequence that serve to protect chromosomal termini from inappropriate degradation, as well as to prevent these natural DNA ends from being recognized as broken DNA (double-strand breaks) and triggering of inappropriate DNA damage responses. Preservation of telomere length requires telomerase, the specialized reverse transcriptase capable of maintaining telomere length via template-mediated addition of telomeric repeats onto the ends of newly synthesized chromosomes. Loss of either end-capping function or telomere length maintenance has been associated with genomic instability or senescence in a variety of settings; therefore, telomeres and telomerase have well-established connections to cancer and aging. It has long been recognized that oxidative stress promotes shortening of telomeres, and that telomerase activity is a radiation-inducible function. However, the effects of ionizing radiation (IR) exposure on telomeres per se are much less well understood and appreciated. To gain a deeper understanding of the roles, telomeres and telomerase play in the response of human cells to IRs of different qualities, we tracked changes in telomeric end-capping function, telomere length, and telomerase activity in panels of mammary epithelial and hematopoietic cell lines exposed to low linear energy transfer (LET) gamma(γ)-rays or high LET, high charge, high energy (HZE) particles, delivered either acutely or at low dose rates. In addition to demonstrating that dysfunctional telomeres contribute to IR-induced mutation frequencies and genome instability, we reveal non-canonical roles for telomerase, in that telomerase activity was required for IR-induced enrichment of mammary epithelial putative stem/progenitor cell populations, a finding also suggestive of cellular reprograming. Taken together, the results reported here establish the critical importance of telomeres and telomerase in the radiation response and, as such, have compelling implications not only for accelerated tumor repopulation following radiation therapy but also for carcinogenic potential following low dose exposures as well, including those of relevance to spaceflight-associated galactic cosmic radiations.
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Affiliation(s)
- Brock J Sishc
- Division of Molecular Radiation Oncology, Department of Radiation Oncology, University of Texas Southwestern Medical Center Dallas , Dallas, TX , USA ; Department of Environmental and Radiological Health Sciences, Colorado State University , Fort Collins, CO , USA
| | - Christopher B Nelson
- Department of Environmental and Radiological Health Sciences, Colorado State University , Fort Collins, CO , USA
| | - Miles J McKenna
- Department of Environmental and Radiological Health Sciences, Colorado State University , Fort Collins, CO , USA
| | - Christine L R Battaglia
- Department of Environmental and Radiological Health Sciences, Colorado State University , Fort Collins, CO , USA
| | - Andrea Herndon
- Department of Environmental and Radiological Health Sciences, Colorado State University , Fort Collins, CO , USA
| | - Rupa Idate
- Department of Environmental and Radiological Health Sciences, Colorado State University , Fort Collins, CO , USA
| | - Howard L Liber
- Department of Environmental and Radiological Health Sciences, Colorado State University , Fort Collins, CO , USA
| | - Susan M Bailey
- Department of Environmental and Radiological Health Sciences, Colorado State University , Fort Collins, CO , USA
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Maida Y, Masutomi K. Telomerase reverse transcriptase moonlights: Therapeutic targets beyond telomerase. Cancer Sci 2015; 106:1486-92. [PMID: 26331588 PMCID: PMC4714691 DOI: 10.1111/cas.12806] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Revised: 08/25/2015] [Accepted: 08/26/2015] [Indexed: 12/26/2022] Open
Abstract
Telomeres, the repetitive sequences at chromosomal ends, protect intact chromosomes. Telomeres progressively shorten through successive rounds of cell divisions, and critically shortened telomeres trigger senescence and apoptosis. The enzyme that elongates telomeres and maintains their structure is known as telomerase. The catalytic subunit of this enzyme (telomerase reverse transcriptase [TERT]) is expressed at a high level in malignant cells, but at a very low level in normal cells. Although telomerase activity was long believed to be the only function of TERT, emerging evidence indicates that TERT plays roles beyond telomeres. For example, TERT contributes to stem cell maintenance and cell reprogramming processes in a manner independent of its canonical function. Even some types of splice variants that lack the telomerase catalytic domains exhibit the functions in a manner that does not depend on telomerase activity. We recently demonstrated that the RNA-dependent RNA polymerase (RdRP) activity of TERT is involved in regulation of gene silencing and heterochromatic transcription. Moreover, TERT RdRP activity is mediated by a newly identified complex, distinct from the authentic telomerase complex, that plays a role in cancer stem cells in a telomere maintenance independent manner. TERT has attracted interest as a molecular target for anticancer treatment, but previous efforts aimed at developing novel therapeutic strategies focused only on the canonical function of TERT. However, accumulating evidence about the non-canonical functions of TERT led us to speculate that the functions other than telomerase might be therapeutic targets as well. In this review, we discuss the non-canonical functions of TERT and their potential applications for anticancer treatment.
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Affiliation(s)
- Yoshiko Maida
- Division of Cancer Stem Cell, National Cancer Center Research Institute, Tokyo, Japan
| | - Kenkichi Masutomi
- Division of Cancer Stem Cell, National Cancer Center Research Institute, Tokyo, Japan
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Wu X, Chen J, Cao Y, Xie B, Li H, Zhou P, Qiu Y, Pang J. Antitumor effect of COOH-terminal polypeptide of human TERT is associated with the declined expression of hTERT and NF-κB p65 in HeLa cells. Oncol Rep 2015; 34:2909-16. [PMID: 26398300 DOI: 10.3892/or.2015.4298] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 07/03/2015] [Indexed: 11/06/2022] Open
Abstract
Human telomerase reverse transcriptase (hTERT) plays an important role in the development of tumors and has been investigated as a potent target for anticancer therapy. In the present study, we constructed a recombinant adenovirus, Ad-EGFP-C197 which was capable of expressing COOH‑terminal polypeptide of hTERT (amino acid 936-1,132, termed as C197 for the reason that it contains 197 amino acids). Infection of HeLa cells with Ad-EGFP-C197 suppressed the activity of telomerase, decreased the expression of hTERT and NF-κB p65, and induced rapid growth delay and apoptosis of HeLa cells in vitro. In nude mice xenografted with HeLa tumors, injection of Ad-EGFP-C197 into the tumor nodule significantly slowed tumor growth and promoted tumor cell apoptosis, as well as reduced the expression of NF-κB p65 in tumor tissues. In the present study, we suggest that the antitumor effect of C197 is associated with the declined expression of hTERT and NF-κB p65. Our results highlight the potential of C197 in tumor therapy.
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Affiliation(s)
- Xian Wu
- Center for Drug Evaluation and Research, School of Pharmaceutical Sciences, Southern Medical University, Baiyun, Guangzhou, Guangdong 510515, P.R. China
| | - Jiasheng Chen
- Center for Drug Evaluation and Research, School of Pharmaceutical Sciences, Southern Medical University, Baiyun, Guangzhou, Guangdong 510515, P.R. China
| | - Ying Cao
- Center for Drug Evaluation and Research, School of Pharmaceutical Sciences, Southern Medical University, Baiyun, Guangzhou, Guangdong 510515, P.R. China
| | - Baoping Xie
- Center for Drug Evaluation and Research, School of Pharmaceutical Sciences, Southern Medical University, Baiyun, Guangzhou, Guangdong 510515, P.R. China
| | - Hongwei Li
- School of Biotechnology, Southern Medical University, Baiyun, Guangzhou, Guangdong 510515, P.R. China
| | - Pingzheng Zhou
- Center for Drug Evaluation and Research, School of Pharmaceutical Sciences, Southern Medical University, Baiyun, Guangzhou, Guangdong 510515, P.R. China
| | - Yuchang Qiu
- Center for Drug Evaluation and Research, School of Pharmaceutical Sciences, Southern Medical University, Baiyun, Guangzhou, Guangdong 510515, P.R. China
| | - Jianxin Pang
- Center for Drug Evaluation and Research, School of Pharmaceutical Sciences, Southern Medical University, Baiyun, Guangzhou, Guangdong 510515, P.R. China
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32
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Reddel RR. Telomere maintenance mechanisms in cancer: clinical implications. Curr Pharm Des 2015; 20:6361-74. [PMID: 24975603 PMCID: PMC4262939 DOI: 10.2174/1381612820666140630101047] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Accepted: 06/26/2014] [Indexed: 01/20/2023]
Abstract
The presence of immortal cell populations with an up-regulated telomere maintenance mechanism (TMM) is an almost universal characteristic of cancers, whereas normal somatic cells are unable to prevent proliferation-associated telomere shortening and have a limited proliferative potential. TMMs and related aspects of telomere structure and function therefore appear to be ideal targets for the development of anticancer therapeutics. Such treatments would be targeted to a specific cancer-related molecular abnormality, and also be broad-spectrum in that they would be expected to be potentially applicable to most cancers. However, the telomere biology of normal and malignant human cells is a relatively young research field with large numbers of unanswered questions, so the optimal design of TMM-targeted therapeutic approaches remains unclear. This review outlines the opportunities and challenges presented by telomeres and TMMs for clinical management of cancer.
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Affiliation(s)
- Roger R Reddel
- Children's Medical Research Institute, 214 Hawkesbury Road, Westmead, New South Wales 2145, Australia.
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33
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Killedar A, Stutz MD, Sobinoff AP, Tomlinson CG, Bryan TM, Beesley J, Chenevix-Trench G, Reddel RR, Pickett HA. A Common Cancer Risk-Associated Allele in the hTERT Locus Encodes a Dominant Negative Inhibitor of Telomerase. PLoS Genet 2015; 11:e1005286. [PMID: 26053551 PMCID: PMC4459975 DOI: 10.1371/journal.pgen.1005286] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 05/14/2015] [Indexed: 12/21/2022] Open
Abstract
The TERT-CLPTM1L region of chromosome 5p15.33 is a multi-cancer susceptibility locus that encodes the reverse transcriptase subunit, hTERT, of the telomerase enzyme. Numerous cancer-associated single-nucleotide polymorphisms (SNPs), including rs10069690, have been identified within the hTERT gene. The minor allele (A) at rs10069690 creates an additional splice donor site in intron 4 of hTERT, and is associated with an elevated risk of multiple cancers including breast and ovarian carcinomas. We previously demonstrated that the presence of this allele resulted in co-production of full length (FL)-hTERT and an alternatively spliced, INS1b, transcript. INS1b does not encode the reverse transcriptase domain required for telomerase enzyme activity, but we show here that INS1b protein retains its ability to bind to the telomerase RNA subunit, hTR. We also show that INS1b expression results in decreased telomerase activity, telomere shortening, and an increased telomere-specific DNA damage response (DDR). We employed antisense oligonucleotides to manipulate endogenous transcript expression in favor of INS1b, which resulted in a decrease in telomerase activity. These data provide the first detailed mechanistic insights into a cancer risk-associated SNP in the hTERT locus, which causes cell type-specific expression of INS1b transcript from the presence of an additional alternative splice site created in intron 4 by the risk allele. We predict that INS1b expression levels cause subtle inadequacies in telomerase-mediated telomere maintenance, resulting in an increased risk of genetic instability and therefore of tumorigenesis. Multiple cancer-associated single nucleotide polymorphisms (SNPs) associated with risk of a wide variety of cancers have been identified in the TERT-CLPTM1L region of 5p15.33, identifying this as a multi-cancer susceptibility locus. hTERT encodes the catalytic subunit of the enzyme telomerase, which is responsible for telomere length maintenance in the germline and in most immortalised cancer cells. To date, very little is known regarding the mechanisms by which specific hTERT SNPs predispose to cancer. In this study, we carried out detailed functional analyses on the intron 4 SNP rs10069690, which is associated with a small, but highly significant risk for many types of cancer. We show that the risk-associated minor allele of this SNP results in an hTERT mRNA splice variant, encoding a catalytically inactive protein which acts as a dominant negative inhibitor of telomerase activity and therefore decreases total telomerase activity. We propose that individuals who carry the rs10069690 minor allele have less telomerase activity in some cell types due to cell type-specific alternative splicing, which may result in slightly shorter telomeres, and hence an increased risk of genetic instability and tumorigenesis.
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Affiliation(s)
- Anagha Killedar
- Telomere Length Regulation Group, Children’s Medical Research Institute, University of Sydney, Westmead, New South Wales, Australia
| | - Michael D. Stutz
- Telomere Length Regulation Group, Children’s Medical Research Institute, University of Sydney, Westmead, New South Wales, Australia
| | - Alexander P. Sobinoff
- Telomere Length Regulation Group, Children’s Medical Research Institute, University of Sydney, Westmead, New South Wales, Australia
| | - Christopher G. Tomlinson
- Cell Biology Unit, Children’s Medical Research Institute, University of Sydney, Westmead, New South Wales, Australia
| | - Tracy M. Bryan
- Cell Biology Unit, Children’s Medical Research Institute, University of Sydney, Westmead, New South Wales, Australia
| | - Jonathan Beesley
- Department of Genetics, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - Georgia Chenevix-Trench
- Department of Genetics, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - Roger R. Reddel
- Cancer Research Unit, Children’s Medical Research Institute, University of Sydney, Westmead, New South Wales, Australia
| | - Hilda A. Pickett
- Telomere Length Regulation Group, Children’s Medical Research Institute, University of Sydney, Westmead, New South Wales, Australia
- * E-mail:
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Affiliation(s)
- James W. Larrick
- Panorama Research Institute and Regenerative Sciences Institute, Sunnyvale, California
| | - Andrew R. Mendelsohn
- Panorama Research Institute and Regenerative Sciences Institute, Sunnyvale, California
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35
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Borah S, Xi L, Zaug AJ, Powell NM, Dancik GM, Cohen SB, Costello JC, Theodorescu D, Cech TR. Cancer. TERT promoter mutations and telomerase reactivation in urothelial cancer. Science 2015; 347:1006-10. [PMID: 25722414 DOI: 10.1126/science.1260200] [Citation(s) in RCA: 226] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Reactivation of telomerase, the chromosome end-replicating enzyme, drives human cell immortality and cancer. Point mutations in the telomerase reverse transcriptase (TERT) gene promoter occur at high frequency in multiple cancers, including urothelial cancer (UC), but their effect on telomerase function has been unclear. In a study of 23 human UC cell lines, we show that these promoter mutations correlate with higher levels of TERT messenger RNA (mRNA), TERT protein, telomerase enzymatic activity, and telomere length. Although previous studies found no relation between TERT promoter mutations and UC patient outcome, we find that elevated TERT mRNA expression strongly correlates with reduced disease-specific survival in two independent UC patient cohorts (n = 35; n = 87). These results suggest that high telomerase activity may be a better marker of aggressive UC tumors than TERT promoter mutations alone.
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Affiliation(s)
- Sumit Borah
- Howard Hughes Medical Institute, University of Colorado BioFrontiers Institute, Boulder, CO 80309, USA. Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309, USA
| | - Linghe Xi
- Howard Hughes Medical Institute, University of Colorado BioFrontiers Institute, Boulder, CO 80309, USA. Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Arthur J Zaug
- Howard Hughes Medical Institute, University of Colorado BioFrontiers Institute, Boulder, CO 80309, USA. Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309, USA
| | - Natasha M Powell
- Howard Hughes Medical Institute, University of Colorado BioFrontiers Institute, Boulder, CO 80309, USA. Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Garrett M Dancik
- Department of Mathematics and Computer Science, Eastern Connecticut State University, Willimantic, CT 06226, USA
| | - Scott B Cohen
- Children's Medical Research Institute and University of Sydney, Westmead, NSW 2145, Australia
| | - James C Costello
- University of Colorado Comprehensive Cancer Center, Aurora, CO 80045, USA. Department of Pharmacology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Dan Theodorescu
- University of Colorado Comprehensive Cancer Center, Aurora, CO 80045, USA. Department of Pharmacology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA. Department of Surgery, University of Colorado, Aurora, CO 80045, USA
| | - Thomas R Cech
- Howard Hughes Medical Institute, University of Colorado BioFrontiers Institute, Boulder, CO 80309, USA. Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309, USA. Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA. University of Colorado Comprehensive Cancer Center, Aurora, CO 80045, USA.
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Fong YW, Ho JJ, Inouye C, Tjian R. The dyskerin ribonucleoprotein complex as an OCT4/SOX2 coactivator in embryonic stem cells. eLife 2014; 3. [PMID: 25407680 PMCID: PMC4270071 DOI: 10.7554/elife.03573] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 11/19/2014] [Indexed: 01/06/2023] Open
Abstract
Acquisition of pluripotency is driven largely at the transcriptional level by activators OCT4, SOX2, and NANOG that must in turn cooperate with diverse coactivators to execute stem cell-specific gene expression programs. Using a biochemically defined in vitro transcription system that mediates OCT4/SOX2 and coactivator-dependent transcription of the Nanog gene, we report the purification and identification of the dyskerin (DKC1) ribonucleoprotein complex as an OCT4/SOX2 coactivator whose activity appears to be modulated by a subset of associated small nucleolar RNAs (snoRNAs). The DKC1 complex occupies enhancers and regulates the expression of key pluripotency genes critical for self-renewal in embryonic stem (ES) cells. Depletion of DKC1 in fibroblasts significantly decreased the efficiency of induced pluripotent stem (iPS) cell generation. This study thus reveals an unanticipated transcriptional role of the DKC1 complex in stem cell maintenance and somatic cell reprogramming. DOI:http://dx.doi.org/10.7554/eLife.03573.001 The stem cells found in an embryo are able to develop into any of the cell types found in the body of the animal: an ability called pluripotency. When a cell becomes a specialized cell type, such as a nerve cell or a muscle cell, it loses this ability. However, mature cells can be reprogrammed back to a pluripotent state by artificially introducing certain proteins (known as ‘reprogramming factors’) into the mature cells. A core group of reprogramming factors are known to activate networks of genes that are normally only expressed in stem cells, and by doing so trigger and maintain a pluripotent state. Other proteins help these core factors to regulate these networks of genes. In 2011, researchers discovered that a protein complex called XPC—which is normally involved in DNA repair—also helps two core reprogramming factors to activate an important gene related to pluripotency. Now, Fong et al., including several of the researchers involved in the 2011 work, have identified another unexpected partner for the same two core reprogramming factors. The protein complex, called DKC1, has a number of known functions related to the processing of RNA molecules. This complex has also been linked to a fatal, rare human disorder called dyskeratosis congenita—a condition that affects many parts of the body, including the skin and bone marrow. Fong et al. found that when embryonic stems cells from mice are depleted of the DKC1 complex, the activation of important pluripotency-related genes by two of the core reprogramming factors is markedly reduced. The XPC and DKC1 protein complexes were found to interact in pluripotent cells, and together they can activate a pluripotency-related gene to a greater extent than either can individually. Fong et al. propose that DKC1 binds to XPC, which in turn binds to two of the core reprogramming factors. The DKC1 complex also binds to RNA molecules, and Fong et al. found that when the DKC1 complex binds to certain RNAs it is more able to help reprogramming factors activate pluripotency-related genes. On the other hand, other RNA molecules seem to inhibit the complex's ability to activate these genes. Mutations identified in people with dyskeratosis congenita can prevent the DKC1 complex from binding to a subset of human RNA molecules. Moreover, the activity of stem cells is impaired in people with this developmental condition. As such, one of the next challenges will be to investigate if these mutations and RNA binding could be linked to problems with the activation of genes related to pluripotency in stem cells. DOI:http://dx.doi.org/10.7554/eLife.03573.002
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Affiliation(s)
- Yick W Fong
- Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, United States
| | - Jaclyn J Ho
- Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, United States
| | - Carla Inouye
- Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, United States
| | - Robert Tjian
- Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, United States
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Zhou J, Ding D, Wang M, Cong YS. Telomerase reverse transcriptase in the regulation of gene expression. BMB Rep 2014; 47:8-14. [PMID: 24388106 PMCID: PMC4163847 DOI: 10.5483/bmbrep.2014.47.1.284] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Indexed: 12/11/2022] Open
Abstract
Telomerase plays a pivotal role in the pathology of aging and cancer by maintaining genome integrity, controlling cell proliferation, and regulating tissue homeostasis. Telomerase is essentially composed of an RNA component, Telomerase RNA or TERC, which serves as a template for telomeric DNA synthesis, and a catalytic subunit, telomerase reverse transcriptase (TERT). The canonical function of TERT is the synthesis of telomeric DNA repeats, and the maintenance of telomere length. However, accumulating evidence indicates that TERT may also have some fundamental functions that are independent of its enzymatic activity. Among these telomere-independent activities of hTERT, the role of hTERT in gene transcription has been investigated in detail. Transcriptional regulation is a fundamental process in biological systems. Several studies have shown a direct involvement of hTERT in gene transcription. This mini-review will focus on the role of hTERT in gene transcription regulation, and discuss its possible mechanisms. [BMB Reports 2014; 47(1): 8-14]
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Affiliation(s)
| | | | | | - Yu-Sheng Cong
- Institute of Aging Research, Hangzhou Normal University School of Medicine, Hangzhou 310036, China
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Abstract
Telomeres protect chromosome ends from degradation and inappropriate DNA damage response activation through their association with specific factors. Interestingly, these telomeric factors are able to localize outside telomeric regions, where they can regulate the transcription of genes involved in metabolism, immunity and differentiation. These findings delineate a signalling pathway by which telomeric changes control the ability of their associated factors to regulate transcription. This mechanism is expected to enable a greater diversity of cellular responses that are adapted to specific cell types and telomeric changes, and may therefore represent a pivotal aspect of development, ageing and telomere-mediated diseases.
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Li Y, Tergaonkar V. Noncanonical functions of telomerase: implications in telomerase-targeted cancer therapies. Cancer Res 2014; 74:1639-44. [PMID: 24599132 DOI: 10.1158/0008-5472.can-13-3568] [Citation(s) in RCA: 124] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Telomerase plays a pivotal role in bypassing cellular senescence and maintaining telomere homeostasis, essential properties required for the sustenance and progression of cancer. However, recent investigations have uncovered extratelomeric properties of telomerase that are independent of its role in telomere extension. This review summarizes recent insights to the noncanonical functions of telomerase reverse transcriptase (TERT) catalytic subunit, in particular in cancer progression, and highlights two major signaling mechanisms involved in the cross-talk with TERT-the NF-κB and Wnt/β-catenin pathways. We propose a feed-forward regulatory loop mechanism underlying TERT activation in cancers in which TERT acts as a transcriptional modulator of oncogenic signaling pathways that sustain its own levels and control the induction of target genes critical for tumor cell survival and proliferation. Finally, we provide a new perspective on telomerase-targeted cancer therapies and suggest possible interventions targeting the nontelomeric roles of TERT. This therapeutic strategy can be used in the future targeting of other telomerase components that exhibit novel nontelomeric functions in cancer and other ailments.
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Affiliation(s)
- Yinghui Li
- Authors' Affiliations: Division of Cancer Genetics and Therapeutics, Laboratory of NF-κB Signaling, Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A*STAR); and Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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Involvement of telomerase reverse transcriptase in heterochromatin maintenance. Mol Cell Biol 2014; 34:1576-93. [PMID: 24550003 DOI: 10.1128/mcb.00093-14] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
In the fission yeast Schizosaccharomyces pombe, centromeric heterochromatin is maintained by an RNA-directed RNA polymerase complex (RDRC) and the RNA-induced transcriptional silencing (RITS) complex in a manner that depends on the generation of short interfering RNA. In association with the telomerase RNA component (TERC), the telomerase reverse transcriptase (TERT) forms telomerase and counteracts telomere attrition, and without TERC, TERT has been implicated in the regulation of heterochromatin at locations distinct from telomeres. Here, we describe a complex composed of human TERT (hTERT), Brahma-related gene 1 (BRG1), and nucleostemin (NS) that contributes to heterochromatin maintenance at centromeres and transposons. This complex produced double-stranded RNAs homologous to centromeric alpha-satellite (alphoid) repeat elements and transposons that were processed into small interfering RNAs targeted to these heterochromatic regions. These small interfering RNAs promoted heterochromatin assembly and mitotic progression in a manner dependent on the RNA interference machinery. These observations implicate the hTERT/BRG1/NS (TBN) complex in heterochromatin assembly at particular sites in the mammalian genome.
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Batista LFZ. Telomere biology in stem cells and reprogramming. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2014; 125:67-88. [PMID: 24993698 DOI: 10.1016/b978-0-12-397898-1.00003-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Telomerase expression in humans is restricted to different populations of stem and progenitor cells, being silenced in most somatic tissues. Efficient telomere homeostasis is essential for embryonic and adult stem cell function and therefore essential for tissue homeostasis throughout organismal life. Accordingly, the mutations in telomerase culminate in reduced stem cell function both in vivo and in vitro and have been associated with tissue dysfunction in human patients. Despite the importance of telomerase for stem cell biology, the mechanisms behind telomerase regulation during development are still poorly understood, mostly due to difficulties in acquiring and maintaining pluripotent stem cell populations in culture. In this chapter, we will analyze recent developments in this field, including the importance of efficient telomere homeostasis in different stem cell types and the role of telomerase in different techniques used for cellular reprogramming.
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Affiliation(s)
- Luis F Z Batista
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA; Department of Developmental Biology, Washington University School of Medicine, St. Louis, Missouri, USA
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