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Sun H, Li X, Long Q, Wang X, Zhu W, Chen E, Zhou W, Yang H, Huang C, Deng W, Chen M. TERC promotes non-small cell lung cancer progression by facilitating the nuclear localization of TERT. iScience 2024; 27:109869. [PMID: 38799568 PMCID: PMC11126826 DOI: 10.1016/j.isci.2024.109869] [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: 12/12/2023] [Revised: 03/26/2024] [Accepted: 04/29/2024] [Indexed: 05/29/2024] Open
Abstract
The core of telomerase consists of the protein subunit telomerase reverse transcriptase (TERT) and the telomerase RNA component (TERC). So far, the role of TERC in cancer development has remained elusive. Here, we found TERC expression elevated in non-small cell lung cancer (NSCLC) tissues, which was associated with disease progression and poor prognosis in patients. Using NSCLC cell lines and xenograft models, we showed that knockdown of TERC caused cell cycle arrest, and inhibition of cell proliferation and migration. Mechanistically, TERC was exported to the cytoplasm by nuclear RNA export factor 1 (NXF1), where it mediated the interaction of TERT with other telomerase subunits. Depletion of TERC hindered the assembly and subsequent nuclear localization of the telomerase complex, preventing TERT from functioning in telomere maintenance and transcription regulation. Our findings suggest that TERC is a potential biomarker for NSCLC diagnosis and prognosis and can be a target for NSCLC treatment.
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Affiliation(s)
- Haohui Sun
- State Key Laboratory of Oncology in South China and Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong 510060, China
| | - Xiaodi Li
- State Key Laboratory of Oncology in South China and Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong 510060, China
| | - Qian Long
- State Key Laboratory of Oncology in South China and Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong 510060, China
- Department of General Surgery, The Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, China
| | - Xiaonan Wang
- State Key Laboratory of Oncology in South China and Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong 510060, China
| | - Wancui Zhu
- State Key Laboratory of Oncology in South China and Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong 510060, China
| | - Enni Chen
- State Key Laboratory of Oncology in South China and Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong 510060, China
| | - Wenhao Zhou
- State Key Laboratory of Oncology in South China and Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong 510060, China
| | - Han Yang
- State Key Laboratory of Oncology in South China and Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong 510060, China
| | - Chuyang Huang
- Department of Urology, Shaoyang Central Hospital, University of South China, Shaoyang, Hunan 422000, China
| | - Wuguo Deng
- State Key Laboratory of Oncology in South China and Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong 510060, China
| | - Miao Chen
- State Key Laboratory of Oncology in South China and Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong 510060, China
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2
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Drobyshev A, Modestov A, Suntsova M, Poddubskaya E, Seryakov A, Moisseev A, Sorokin M, Tkachev V, Zakharova G, Simonov A, Zolotovskaia MA, Buzdin A. Pan-cancer experimental characteristic of human transcriptional patterns connected with telomerase reverse transcriptase ( TERT) gene expression status. Front Genet 2024; 15:1401100. [PMID: 38859942 PMCID: PMC11163056 DOI: 10.3389/fgene.2024.1401100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Accepted: 05/08/2024] [Indexed: 06/12/2024] Open
Abstract
The TERT gene encodes the reverse transcriptase subunit of telomerase and is normally transcriptionally suppressed in differentiated human cells but reactivated in cancers where its expression is frequently associated with poor survival prognosis. Here we experimentally assessed the RNA sequencing expression patterns associated with TERT transcription in 1039 human cancer samples of 27 tumor types. We observed a bimodal distribution of TERT expression where ∼27% of cancer samples did not express TERT and the rest showed a bell-shaped distribution. Expression of TERT strongly correlated with 1443 human genes including 103 encoding transcriptional factor proteins. Comparison of TERT- positive and negative cancers showed the differential activation of 496 genes and 1975 molecular pathways. Therein, 32/38 (84%) of DNA repair pathways were hyperactivated in TERT+ cancers which was also connected with accelerated replication, transcription, translation, and cell cycle progression. In contrast, the level of 40 positive cell cycle regulator proteins and a set of epithelial-to-mesenchymal transition pathways was specific for the TERT- group suggesting different proliferation strategies for both groups of cancer. Our pilot study showed that the TERT+ group had ∼13% of cancers with C228T or C250T mutated TERT promoter. However, the presence of promoter mutations was not associated with greater TERT expression compared with other TERT+ cancers, suggesting parallel mechanisms of its transcriptional activation in cancers. In addition, we detected a decreased expression of L1 retrotransposons in the TERT+ group, and further decreased L1 expression in promoter mutated TERT+ cancers. TERT expression was correlated with 17 genes encoding molecular targets of cancer therapeutics and may relate to differential survival patterns of TERT- positive and negative cancers.
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Affiliation(s)
- Aleksey Drobyshev
- Endocrinology Research Center, Moscow, Russia
- Institute of Personalized Oncology, I. M. Sechenov First Moscow State Medical University, Moscow, Russia
| | - Alexander Modestov
- Institute of Personalized Oncology, I. M. Sechenov First Moscow State Medical University, Moscow, Russia
| | - Maria Suntsova
- Endocrinology Research Center, Moscow, Russia
- Institute of Personalized Oncology, I. M. Sechenov First Moscow State Medical University, Moscow, Russia
| | - Elena Poddubskaya
- Institute of Personalized Oncology, I. M. Sechenov First Moscow State Medical University, Moscow, Russia
- Clinical Center Vitamed, Moscow, Russia
| | | | - Aleksey Moisseev
- Institute of Personalized Oncology, I. M. Sechenov First Moscow State Medical University, Moscow, Russia
| | - Maksim Sorokin
- Endocrinology Research Center, Moscow, Russia
- Institute of Personalized Oncology, I. M. Sechenov First Moscow State Medical University, Moscow, Russia
| | | | - Galina Zakharova
- Institute of Personalized Oncology, I. M. Sechenov First Moscow State Medical University, Moscow, Russia
| | - Aleksander Simonov
- Institute of Personalized Oncology, I. M. Sechenov First Moscow State Medical University, Moscow, Russia
| | - Marianna A. Zolotovskaia
- Endocrinology Research Center, Moscow, Russia
- Institute of Personalized Oncology, I. M. Sechenov First Moscow State Medical University, Moscow, Russia
- Moscow Center for Advanced Studies 20, Moscow, Russia
| | - Anton Buzdin
- Endocrinology Research Center, Moscow, Russia
- Institute of Personalized Oncology, I. M. Sechenov First Moscow State Medical University, Moscow, Russia
- Moscow Center for Advanced Studies 20, Moscow, Russia
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Moscow, Russia
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Valeeva LR, Abdulkina LR, Agabekian IA, Shakirov EV. Telomere biology and ribosome biogenesis: structural and functional interconnections. Biochem Cell Biol 2023; 101:394-409. [PMID: 36989538 DOI: 10.1139/bcb-2022-0383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/31/2023] Open
Abstract
Telomeres are nucleoprotein structures that play a pivotal role in the protection and maintenance of eukaryotic chromosomes. Telomeres and the enzyme telomerase, which replenishes telomeric DNA lost during replication, are important factors necessary to ensure continued cell proliferation. Cell proliferation is also dependent on proper and efficient protein synthesis, which is carried out by ribosomes. Mutations in genes involved in either ribosome biogenesis or telomere biology result in cellular abnormalities and can cause human genetic diseases, defined as ribosomopathies and telomeropathies, respectively. Interestingly, recent discoveries indicate that many of the ribosome assembly and rRNA maturation factors have additional noncanonical functions in telomere biology. Similarly, several key proteins and enzymes involved in telomere biology, including telomerase, have unexpected roles in rRNA transcription and maturation. These observations point to an intriguing cross-talk mechanism potentially explaining the multiple pleiotropic symptoms of mutations in many causal genes identified in various telomeropathy and ribosomopathy diseases. In this review, we provide a brief summary of eukaryotic telomere and rDNA loci structures, highlight several universal features of rRNA and telomerase biogenesis, evaluate intriguing interconnections between telomere biology and ribosome assembly, and conclude with an assessment of overlapping features of human diseases of telomeropathies and ribosomopathies.
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Affiliation(s)
- Liia R Valeeva
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan 420008, Republic of Tatarstan, Russia
- Department of Biological Sciences, College of Science, Marshall University, Huntington, WV 25701, USA
| | - Liliia R Abdulkina
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan 420008, Republic of Tatarstan, Russia
| | - Inna A Agabekian
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan 420008, Republic of Tatarstan, Russia
| | - Eugene V Shakirov
- Department of Biological Sciences, College of Science, Marshall University, Huntington, WV 25701, USA
- Department of Biomedical Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, WV 25755, USA
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Yu P, Qu N, Zhu R, Hu J, Han P, Wu J, Tan L, Gan H, He C, Fang C, Lei Y, Li J, He C, Lan F, Shi X, Wei W, Wang Y, Ji Q, Yu FX, Wang YL. TERT accelerates BRAF mutant-induced thyroid cancer dedifferentiation and progression by regulating ribosome biogenesis. SCIENCE ADVANCES 2023; 9:eadg7125. [PMID: 37647391 PMCID: PMC10468137 DOI: 10.1126/sciadv.adg7125] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 07/27/2023] [Indexed: 09/01/2023]
Abstract
TERT reactivation occurs frequently in human malignancies, especially advanced cancers. However, in vivo functions of TERT reactivation in cancer progression and the underlying mechanism are not fully understood. In this study, we expressed TERT and/or active BRAF (BRAF V600E) specifically in mouse thyroid epithelium. While BRAF V600E alone induced papillary thyroid cancer (PTC), coexpression of BRAF V600E and TERT resulted in poorly differentiated thyroid carcinoma (PDTC). Spatial transcriptome analysis revealed that tumors from mice coexpressing BRAF V600E and TERT were highly heterogeneous, and cell dedifferentiation was positively correlated with ribosomal biogenesis. Mechanistically, TERT boosted ribosomal RNA (rRNA) expression and protein synthesis by interacting with multiple proteins involved in ribosomal biogenesis. Furthermore, we found that CX-5461, an rRNA transcription inhibitor, effectively blocked proliferation and induced redifferentiation of thyroid cancer. Thus, TERT promotes thyroid cancer progression by inducing cancer cell dedifferentiation, and ribosome inhibition represents a potential strategy to treat TERT-reactivated cancers.
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Affiliation(s)
- Pengcheng Yu
- Department of Head and Neck Surgery, Fudan University Shanghai Cancer Center, Shanghai, China
- Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
- Institute of Pediatrics, Children's Hospital of Fudan University, Shanghai, China
- Institutes of Biomedical Sciences, Shanghai Medical College, Fudan University, Shanghai, China
| | - Ning Qu
- Department of Head and Neck Surgery, Fudan University Shanghai Cancer Center, Shanghai, China
- Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Rui Zhu
- Institute of Pediatrics, Children's Hospital of Fudan University, Shanghai, China
- Institutes of Biomedical Sciences, Shanghai Medical College, Fudan University, Shanghai, China
| | - Jiaqian Hu
- Department of Head and Neck Surgery, Fudan University Shanghai Cancer Center, Shanghai, China
- Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Peizhen Han
- Department of Head and Neck Surgery, Fudan University Shanghai Cancer Center, Shanghai, China
- Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Jiahao Wu
- Department of Head and Neck Surgery, Fudan University Shanghai Cancer Center, Shanghai, China
- Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Licheng Tan
- Department of Head and Neck Surgery, Fudan University Shanghai Cancer Center, Shanghai, China
- Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Hualei Gan
- Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
- Department of Pathology, Fudan University Shanghai Cancer Center, Shanghai, China
| | - Cong He
- Department of Head and Neck Surgery, Fudan University Shanghai Cancer Center, Shanghai, China
- Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Chuantao Fang
- Institute of Pediatrics, Children's Hospital of Fudan University, Shanghai, China
- Institutes of Biomedical Sciences, Shanghai Medical College, Fudan University, Shanghai, China
| | - Yubin Lei
- Institute of Pediatrics, Children's Hospital of Fudan University, Shanghai, China
- Institutes of Biomedical Sciences, Shanghai Medical College, Fudan University, Shanghai, China
| | - Jian Li
- Institute of Pediatrics, Children's Hospital of Fudan University, Shanghai, China
- Institutes of Biomedical Sciences, Shanghai Medical College, Fudan University, Shanghai, China
| | - Chenxi He
- Institutes of Biomedical Sciences, Shanghai Medical College, Fudan University, Shanghai, China
| | - Fei Lan
- Institutes of Biomedical Sciences, Shanghai Medical College, Fudan University, Shanghai, China
| | - Xiao Shi
- Department of Head and Neck Surgery, Fudan University Shanghai Cancer Center, Shanghai, China
- Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Wenjun Wei
- Department of Head and Neck Surgery, Fudan University Shanghai Cancer Center, Shanghai, China
- Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Yu Wang
- Department of Head and Neck Surgery, Fudan University Shanghai Cancer Center, Shanghai, China
- Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Qinghai Ji
- Department of Head and Neck Surgery, Fudan University Shanghai Cancer Center, Shanghai, China
- Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Fa-Xing Yu
- Institute of Pediatrics, Children's Hospital of Fudan University, Shanghai, China
- Institutes of Biomedical Sciences, Shanghai Medical College, Fudan University, Shanghai, China
| | - Yu-Long Wang
- Department of Head and Neck Surgery, Fudan University Shanghai Cancer Center, Shanghai, China
- Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
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Waksal JA, Bruedigam C, Komrokji RS, Jamieson CHM, Mascarenhas JO. Telomerase-targeted therapies in myeloid malignancies. Blood Adv 2023; 7:4302-4314. [PMID: 37216228 PMCID: PMC10424149 DOI: 10.1182/bloodadvances.2023009903] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 05/08/2023] [Accepted: 05/14/2023] [Indexed: 05/24/2023] Open
Abstract
Human telomeres are tandem arrays that are predominantly composed of 5'-TTAGGG-3' nucleotide sequences at the terminal ends of chromosomes. These sequences serve 2 primary functions: they preserve genomic integrity by protecting the ends of chromosomes, preventing inappropriate degradation by DNA repair mechanisms, and they prevent loss of genetic information during cellular division. When telomeres shorten to reach a critical length, termed the Hayflick limit, cell senescence or death is triggered. Telomerase is a key enzyme involved in synthesizing and maintaining the length of telomeres within rapidly dividing cells and is upregulated across nearly all malignant cells. Accordingly, targeting telomerase to inhibit uncontrolled cell growth has been an area of great interest for decades. In this review, we summarize telomere and telomerase biology because it relates to both physiologic and malignant cells. We discuss the development of telomere- and telomerase-targeted therapeutic candidates within the realm of myeloid malignancies. We overview all mechanisms of targeting telomerase that are currently in development, with a particular focus on imetelstat, an oligonucleotide with direct telomerase inhibitory properties that has advanced the furthest in clinical development and has demonstrated promising data in multiple myeloid malignancies.
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Affiliation(s)
- Julian A. Waksal
- Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Claudia Bruedigam
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
- School of Biomedical Sciences, The University of Queensland, Brisbane, Australia
| | | | | | - John O. Mascarenhas
- Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY
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Udroiu I, Marinaccio J, Sgura A. Many Functions of Telomerase Components: Certainties, Doubts, and Inconsistencies. Int J Mol Sci 2022; 23:ijms232315189. [PMID: 36499514 PMCID: PMC9736166 DOI: 10.3390/ijms232315189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 11/23/2022] [Accepted: 11/29/2022] [Indexed: 12/12/2022] Open
Abstract
A growing number of studies have evidenced non-telomeric functions of "telomerase". Almost all of them, however, investigated the non-canonical effects of the catalytic subunit TERT, and not the telomerase ribonucleoprotein holoenzyme. These functions mainly comprise signal transduction, gene regulation and the increase of anti-oxidative systems. Although less studied, TERC (the RNA component of telomerase) has also been shown to be involved in gene regulation, as well as other functions. All this has led to the publication of many reviews on the subject, which, however, are often disseminating personal interpretations of experimental studies of other researchers as original proofs. Indeed, while some functions such as gene regulation seem ascertained, especially because mechanistic findings have been provided, other ones remain dubious and/or are contradicted by other direct or indirect evidence (e.g., telomerase activity at double-strand break site, RNA polymerase activity of TERT, translation of TERC, mitochondrion-processed TERC). In a critical study of the primary evidence so far obtained, we show those functions for which there is consensus, those showing contradictory results and those needing confirmation. The resulting picture, together with some usually neglected aspects, seems to indicate a link between TERT and TERC functions and cellular stemness and gives possible directions for future research.
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Regulation of RNA Polymerase I Stability and Function. Cancers (Basel) 2022; 14:cancers14235776. [PMID: 36497261 PMCID: PMC9737084 DOI: 10.3390/cancers14235776] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 11/21/2022] [Accepted: 11/21/2022] [Indexed: 11/27/2022] Open
Abstract
RNA polymerase I is a highly processive enzyme with fast initiation and elongation rates. The structure of Pol I, with its in-built RNA cleavage ability and incorporation of subunits homologous to transcription factors, enables it to quickly and efficiently synthesize the enormous amount of rRNA required for ribosome biogenesis. Each step of Pol I transcription is carefully controlled. However, cancers have highjacked these control points to switch the enzyme, and its transcription, on permanently. While this provides an exceptional benefit to cancer cells, it also creates a potential cancer therapeutic vulnerability. We review the current research on the regulation of Pol I transcription, and we discuss chemical biology efforts to develop new targeted agents against this process. Lastly, we highlight challenges that have arisen from the introduction of agents with promiscuous mechanisms of action and provide examples of agents with specificity and selectivity against Pol I.
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González-Moles MÁ, Moya-González E, García-Ferrera A, Nieto-Casado P, Ramos-García P. Prognostic and Clinicopathological Significance of Telomerase Reverse Transcriptase Upregulation in Oral Cancer: A Systematic Review and Meta-Analysis. Cancers (Basel) 2022; 14:cancers14153673. [PMID: 35954336 PMCID: PMC9367569 DOI: 10.3390/cancers14153673] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 07/18/2022] [Accepted: 07/26/2022] [Indexed: 12/07/2022] Open
Abstract
The aim of this systematic review and meta-analysis was to evaluate the current evidence on the prognostic and clinicopathological significance value of telomerase reverse transcriptase (TERT) upregulation in patients with oral squamous cell carcinoma (OSCC). PubMed, Embase, Web of Science, and Scopus were searched for studies published before April 2022, not restricted by date or publication language. The methodological quality of primary-level studies was critically assessed using the Quality in Prognosis Studies (QUIPS) tool. We carried out meta-analyses, explored heterogeneity and its sources, and performed subgroup, meta-regression, sensitivity, and small-study effects analyses. Twenty-one studies (1698 patients) met inclusion criteria. TERT protein overexpression was significantly associated with worse overall survival (hazard ratio [HR] = 3.01, 95% CI = 1.70−5.35, p < 0.001), disease-free survival (HR = 4.03, 95% CI = 1.80−9.05, p = 0.001), and higher histological grade OSCC (odds ratio [OR] = 3.20, 95% CI = 1.83−5.62, p < 0.001). These large effect sizes were consistently obtained by homogeneous subgroups (p > 0.10, I2 = 0.0, respectively), which reflects a high quality of evidence. On the other hand, TERT gene mutations obtained constantly nonsignificant null effect sizes for all outcomes investigated, evidencing no prognostic or clinicopathological value. In conclusion, our findings indicate that TERT upregulation is a prognostic indicator of poor survival in oral cancer. Our findings support the immunohistochemical assessment of TERT overexpression, which could probably be incorporated into the prognostic evaluation of OSCC.
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Affiliation(s)
- Miguel Ángel González-Moles
- School of Dentistry, University of Granada, 18011 Granada, Spain; (E.M.-G.); (A.G.-F.); (P.N.-C.)
- Instituto de Investigación Biosanitaria ibs.GRANADA, 18012 Granada, Spain
- Correspondence: (M.Á.G.-M.); (P.R.-G.)
| | - Eloísa Moya-González
- School of Dentistry, University of Granada, 18011 Granada, Spain; (E.M.-G.); (A.G.-F.); (P.N.-C.)
- Instituto de Investigación Biosanitaria ibs.GRANADA, 18012 Granada, Spain
| | - Alberto García-Ferrera
- School of Dentistry, University of Granada, 18011 Granada, Spain; (E.M.-G.); (A.G.-F.); (P.N.-C.)
- Instituto de Investigación Biosanitaria ibs.GRANADA, 18012 Granada, Spain
| | - Paola Nieto-Casado
- School of Dentistry, University of Granada, 18011 Granada, Spain; (E.M.-G.); (A.G.-F.); (P.N.-C.)
- Instituto de Investigación Biosanitaria ibs.GRANADA, 18012 Granada, Spain
| | - Pablo Ramos-García
- School of Dentistry, University of Granada, 18011 Granada, Spain; (E.M.-G.); (A.G.-F.); (P.N.-C.)
- Instituto de Investigación Biosanitaria ibs.GRANADA, 18012 Granada, Spain
- Correspondence: (M.Á.G.-M.); (P.R.-G.)
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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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10
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Xie X, Li M, Zhou M, Chow SF, Tsang CK. Pharmacological preconditioning by TERT inhibitor BIBR1532 confers neuronal ischemic tolerance through TERT-mediated transcriptional reprogramming. J Neurochem 2021; 159:690-709. [PMID: 34532857 DOI: 10.1111/jnc.15515] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 08/25/2021] [Accepted: 09/13/2021] [Indexed: 11/30/2022]
Abstract
After a sublethal ischemic preconditioning (IPC) stimulus, the brain has a remarkable capability of acquiring tolerance to subsequent ischemic insult by establishing precautionary self-protective mechanism. Understanding this endogenous mechanism would reveal novel and effective neuroprotective targets for ischemic brain injury. Our previous study has implied that telomerase reverse transcriptase (TERT) is associated with IPC-induced tolerance. Here, we investigated the mechanism of TERT-mediated ischemic tolerance. Preconditioning was modeled by oxygen-glucose deprivation (OGD) and by TERT inhibitor BIBR1532 in primary neurons. We found that ischemic tolerance was conferred by BIBR1532 preconditioning. We used the Cleavage-Under-Targets-And-Tagmentation approach, a recently developed method with superior signal-to-noise ratio, to comprehensively map the genomic binding sites of TERT in primary neurons, and showed that more than 50% of TERT-binding sites were located at the promoter regions. Mechanistically, we demonstrated that under normal conditions TERT physically bound to many previously unknown genomic loci in neurons, whereas BIBR1532 preconditioning significantly altered TERT-chromatin-binding profile. Intriguingly, we found that BIBR1532-preconditioned neurons showed significant up-regulation of promoter binding of TERT to the mitochondrial anti-oxidant genes, which were correlated with their elevated expression. Functional analysis further indicated that BIBR1532-preconditioning significantly reduced ROS levels and enhanced tolerance to severe ischemia-induced mitochondrial oxidative stress in neurons in a TERT-dependent manner. Together, these results demonstrate that BIBR1532 confers neuronal ischemic tolerance through TERT-mediated transcriptional reprogramming for up-regulation of mitochondrial anti-oxidation gene expression, suggesting the translational potential of BIBR1532 as a therapeutic agent for the treatment of cerebral ischemic injury and oxidative stress-induced neurological disorders.
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Affiliation(s)
- Xuemin Xie
- Clinical Neuroscience Institute, The First Affiliated Hospital of Jinan University, Guangzhou, China.,Department of Neurology, The First Clinical Medical School of Jinan University, Guangzhou, China
| | - Mingxi Li
- Clinical Neuroscience Institute, The First Affiliated Hospital of Jinan University, Guangzhou, China.,Department of Neurology, The First Clinical Medical School of Jinan University, Guangzhou, China
| | - Mengyao Zhou
- Clinical Neuroscience Institute, The First Affiliated Hospital of Jinan University, Guangzhou, China.,Core Research Center, The First Affiliated Hospital of Jinan University, Guangzhou, China
| | - Shing Fung Chow
- Department of Pharmacology and Pharmacy, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong Special Administrative Region, Hong Kong, China
| | - Chi Kwan Tsang
- Clinical Neuroscience Institute, The First Affiliated Hospital of Jinan University, Guangzhou, China
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11
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Telomerase RNA recruits RNA polymerase II to target gene promoters to enhance myelopoiesis. Proc Natl Acad Sci U S A 2021; 118:2015528118. [PMID: 34353901 DOI: 10.1073/pnas.2015528118] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Dyskeratosis congenita (DC) is a rare inherited bone marrow failure and cancer predisposition syndrome caused by mutations in telomerase or telomeric proteins. Here, we report that zebrafish telomerase RNA (terc) binds to specific DNA sequences of master myeloid genes and controls their expression by recruiting RNA Polymerase II (Pol II). Zebrafish terc harboring the CR4-CR5 domain mutation found in DC patients hardly interacted with Pol II and failed to regulate myeloid gene expression in vivo and to increase their transcription rates in vitro. Similarly, TERC regulated myeloid gene expression and Pol II promoter occupancy in human myeloid progenitor cells. Strikingly, induced pluripotent stem cells derived from DC patients with a TERC mutation in the CR4-CR5 domain showed impaired myelopoiesis, while those with mutated telomerase catalytic subunit differentiated normally. Our findings show that TERC acts as a transcription factor, revealing a target for therapeutic intervention in DC patients.
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12
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Akincilar SC, Chan CHT, Ng QF, Fidan K, Tergaonkar V. Non-canonical roles of canonical telomere binding proteins in cancers. Cell Mol Life Sci 2021; 78:4235-4257. [PMID: 33599797 PMCID: PMC8164586 DOI: 10.1007/s00018-021-03783-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 12/28/2020] [Accepted: 01/29/2021] [Indexed: 02/06/2023]
Abstract
Reactivation of telomerase is a major hallmark observed in 90% of all cancers. Yet paradoxically, enhanced telomerase activity does not correlate with telomere length and cancers often possess short telomeres; suggestive of supplementary non-canonical roles that telomerase might play in the development of cancer. Moreover, studies have shown that aberrant expression of shelterin proteins coupled with their release from shortening telomeres can further promote cancer by mechanisms independent of their telomeric role. While targeting telomerase activity appears to be an attractive therapeutic option, this approach has failed in clinical trials due to undesirable cytotoxic effects on stem cells. To circumvent this concern, an alternative strategy could be to target the molecules involved in the non-canonical functions of telomeric proteins. In this review, we will focus on emerging evidence that has demonstrated the non-canonical roles of telomeric proteins and their impact on tumorigenesis. Furthermore, we aim to address current knowledge gaps in telomeric protein functions and propose future research approaches that can be undertaken to achieve this.
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Affiliation(s)
- Semih Can Akincilar
- Division of Cancer Genetics and Therapeutics, Laboratory of NFκB Signaling, Institute of Molecular and Cell Biology (IMCB), A*STAR (Agency for Science, Technology and Research), Proteos, 61, Biopolis Drive, Singapore, 138673, Singapore
| | - Claire Hian Tzer Chan
- Division of Cancer Genetics and Therapeutics, Laboratory of NFκB Signaling, Institute of Molecular and Cell Biology (IMCB), A*STAR (Agency for Science, Technology and Research), Proteos, 61, Biopolis Drive, Singapore, 138673, Singapore
| | - Qin Feng Ng
- Division of Cancer Genetics and Therapeutics, Laboratory of NFκB Signaling, Institute of Molecular and Cell Biology (IMCB), A*STAR (Agency for Science, Technology and Research), Proteos, 61, Biopolis Drive, Singapore, 138673, Singapore
| | - Kerem Fidan
- Division of Cancer Genetics and Therapeutics, Laboratory of NFκB Signaling, Institute of Molecular and Cell Biology (IMCB), A*STAR (Agency for Science, Technology and Research), Proteos, 61, Biopolis Drive, Singapore, 138673, Singapore
| | - Vinay Tergaonkar
- Division of Cancer Genetics and Therapeutics, Laboratory of NFκB Signaling, Institute of Molecular and Cell Biology (IMCB), A*STAR (Agency for Science, Technology and Research), Proteos, 61, Biopolis Drive, Singapore, 138673, Singapore.
- Department of Pathology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117593, Singapore.
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13
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Fernandes SG, Dsouza R, Pandya G, Kirtonia A, Tergaonkar V, Lee SY, Garg M, Khattar E. Role of Telomeres and Telomeric Proteins in Human Malignancies and Their Therapeutic Potential. Cancers (Basel) 2020; 12:E1901. [PMID: 32674474 PMCID: PMC7409176 DOI: 10.3390/cancers12071901] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 07/10/2020] [Accepted: 07/13/2020] [Indexed: 12/19/2022] Open
Abstract
Telomeres are the ends of linear chromosomes comprised of repetitive nucleotide sequences in humans. Telomeres preserve chromosomal stability and genomic integrity. Telomere length shortens with every cell division in somatic cells, eventually resulting in replicative senescence once telomere length becomes critically short. Telomere shortening can be overcome by telomerase enzyme activity that is undetectable in somatic cells, while being active in germline cells, stem cells, and immune cells. Telomeres are bound by a shelterin complex that regulates telomere lengthening as well as protects them from being identified as DNA damage sites. Telomeres are transcribed by RNA polymerase II, and generate a long noncoding RNA called telomeric repeat-containing RNA (TERRA), which plays a key role in regulating subtelomeric gene expression. Replicative immortality and genome instability are hallmarks of cancer and to attain them cancer cells exploit telomere maintenance and telomere protection mechanisms. Thus, understanding the role of telomeres and their associated proteins in cancer initiation, progression and treatment is very important. The present review highlights the critical role of various telomeric components with recently established functions in cancer. Further, current strategies to target various telomeric components including human telomerase reverse transcriptase (hTERT) as a therapeutic approach in human malignancies are discussed.
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Affiliation(s)
- Stina George Fernandes
- Sunandan Divatia School of Science, SVKM’s NMIMS (Deemed to be University), Vile Parle West, Mumbai 400056, India; (S.G.F.); (R.D.)
| | - Rebecca Dsouza
- Sunandan Divatia School of Science, SVKM’s NMIMS (Deemed to be University), Vile Parle West, Mumbai 400056, India; (S.G.F.); (R.D.)
| | - Gouri Pandya
- Amity Institute of Molecular Medicine and Stem Cell Research (AIMMSCR), Amity University Uttar Pradesh, Noida 201313, India; (G.P.); (A.K.)
| | - Anuradha Kirtonia
- Amity Institute of Molecular Medicine and Stem Cell Research (AIMMSCR), Amity University Uttar Pradesh, Noida 201313, India; (G.P.); (A.K.)
| | - Vinay Tergaonkar
- Laboratory of NF-κB Signaling, Institute of Molecular and Cell Biology (IMCB), 61 Biopolis Drive, Proteos, Singapore 138673, Singapore; (V.T.); (S.Y.L.)
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore (NUS), Singapore 117597, Singapore
- Department of Pathology, Yong Loo Lin School of Medicine, National University of Singapore (NUS), Singapore 117597, Singapore
| | - Sook Y. Lee
- Laboratory of NF-κB Signaling, Institute of Molecular and Cell Biology (IMCB), 61 Biopolis Drive, Proteos, Singapore 138673, Singapore; (V.T.); (S.Y.L.)
| | - Manoj Garg
- Amity Institute of Molecular Medicine and Stem Cell Research (AIMMSCR), Amity University Uttar Pradesh, Noida 201313, India; (G.P.); (A.K.)
| | - Ekta Khattar
- Sunandan Divatia School of Science, SVKM’s NMIMS (Deemed to be University), Vile Parle West, Mumbai 400056, India; (S.G.F.); (R.D.)
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14
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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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15
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Luo Z, Wang W, Li F, Songyang Z, Feng X, Xin C, Dai Z, Xiong Y. Pan-cancer analysis identifies telomerase-associated signatures and cancer subtypes. Mol Cancer 2019; 18:106. [PMID: 31179925 PMCID: PMC6556968 DOI: 10.1186/s12943-019-1035-x] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 05/29/2019] [Indexed: 01/09/2023] Open
Abstract
Background Cancer cells become immortalized through telomere maintenance mechanisms, such as telomerase reverse transcriptase (TERT) activation. In addition to maintaining telomere length, TERT activates manifold cell survival signaling pathways. However, telomerase-associated gene signatures in cancer remain elusive. Methods We performed a systematic analysis of TERT high (TERThigh) and low (TERTlow) cancers using multidimensional data from The Cancer Genome Atlas (TCGA). Multidimensional data were analyzed by propensity score matching weight algorithm. Coexpression networks were constructed by weight gene coexpression network analysis (WGCNA). Random forest classifiers were generated to identify cancer subtypes. Results The TERThigh-specific mRNA expression signature is associated with cell cycle-related coexpression modules across cancer types. Experimental screening of hub genes in the cell cycle module suggested TPX2 and EXO1 as potential regulators of telomerase activity and cell survival. MiRNA analysis revealed that the TERThigh-specific miR-17-92 cluster can target biological processes enriched in TERTlow cancer and that its expression is negatively correlated with the tumor/normal telomere length ratio. Intriguingly, TERThigh cancers tend to have mutations in extracellular matrix organization genes and amplify MAPK signaling. By mining the clinical actionable gene database, we uncovered a number of TERThigh-specific somatic mutations, amplifications and high expression genes containing therapeutic targets. Finally, a random forest classifier integrating telomerase-associated multi-omics signatures identifies two cancer subtypes showed profound differences in telomerase activity and patient survival. Conclusions In summary, our results depict a telomerase-associated molecular landscape in cancers and provide therapeutic opportunities for cancer treatment. Electronic supplementary material The online version of this article (10.1186/s12943-019-1035-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Zhenhua Luo
- Key Laboratory of Gene Engineering of the Ministry of Education and State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510006, China.,Division of Gastroenterology, Hepatology and Nutrition, Cincinnati Children's Hospital Medical Center and the Department of Pediatrics Cincinnati, Ohio, 45229, USA
| | - Weixu Wang
- College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China
| | - Feng Li
- Key Laboratory of Gene Engineering of the Ministry of Education and State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510006, China
| | - Zhou Songyang
- Key Laboratory of Gene Engineering of the Ministry of Education and State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510006, China.,Verna and Marrs Mclean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA
| | - Xuyang Feng
- Department of Cancer Biology, University of Cincinnati, Cincinnati, OH, 45230, USA.,The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510275, China
| | - Changchang Xin
- Key Laboratory of Gene Engineering of the Ministry of Education and State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510006, China
| | - Zhiming Dai
- School of Data and Computer Science, Sun Yat-Sen University, Guangzhou, 510006, China.
| | - Yuanyan Xiong
- Key Laboratory of Gene Engineering of the Ministry of Education and State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510006, China.
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16
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Iarovaia OV, Minina EP, Sheval EV, Onichtchouk D, Dokudovskaya S, Razin SV, Vassetzky YS. Nucleolus: A Central Hub for Nuclear Functions. Trends Cell Biol 2019; 29:647-659. [PMID: 31176528 DOI: 10.1016/j.tcb.2019.04.003] [Citation(s) in RCA: 91] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 04/24/2019] [Accepted: 04/26/2019] [Indexed: 12/19/2022]
Abstract
The nucleolus is the largest and most studied nuclear body, but its role in nuclear function is far from being comprehensively understood. Much work on the nucleolus has focused on its role in regulating RNA polymerase I (RNA Pol I) transcription and ribosome biogenesis; however, emerging evidence points to the nucleolus as an organizing hub for many nuclear functions, accomplished via the shuttling of proteins and nucleic acids between the nucleolus and nucleoplasm. Here, we discuss the cellular mechanisms affected by shuttling of nucleolar components, including the 3D organization of the genome, stress response, DNA repair and recombination, transcription regulation, telomere maintenance, and other essential cellular functions.
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Affiliation(s)
- Olga V Iarovaia
- Institute of Gene Biology of the Russian Academy of Sciences, 119334 Moscow, Russia; LIA 1066 LFR2O French-Russian Joint Cancer Research Laboratory, 94805 Villejuif, France
| | - Elizaveta P Minina
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Eugene V Sheval
- LIA 1066 LFR2O French-Russian Joint Cancer Research Laboratory, 94805 Villejuif, France; Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119991 Moscow, Russia; Faculty of Biology, Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Daria Onichtchouk
- Developmental Biology Unit, Department of Biology I, University of Freiburg, Hauptstrasse 1, D-79104 Freiburg, Germany
| | - Svetlana Dokudovskaya
- LIA 1066 LFR2O French-Russian Joint Cancer Research Laboratory, 94805 Villejuif, France; UMR8126, Université Paris-Sud, CNRS, Institut Gustave Roussy, 94805 Villejuif, France
| | - Sergey V Razin
- Institute of Gene Biology of the Russian Academy of Sciences, 119334 Moscow, Russia; LIA 1066 LFR2O French-Russian Joint Cancer Research Laboratory, 94805 Villejuif, France; Faculty of Biology, Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Yegor S Vassetzky
- LIA 1066 LFR2O French-Russian Joint Cancer Research Laboratory, 94805 Villejuif, France; Koltzov Institute of Developmental Biology of the Russian Academy of Sciences, 119334 Moscow, Russia; UMR8126, Université Paris-Sud, CNRS, Institut Gustave Roussy, 94805 Villejuif, France.
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17
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Abstract
Telomeres are specialised structures at the end of linear chromosomes. They consist of tandem repeats of the hexanucleotide sequence TTAGGG, as well as a protein complex called shelterin. Together, they form a protective loop structure against chromosome fusion and degradation. Shortening or damage to telomeres and opening of the loop induce an uncapped state that triggers a DNA damage response resulting in senescence or apoptosis.Average telomere length, usually measured in human blood lymphocytes, was thought to be a biomarker for ageing, survival and mortality. However, it becomes obvious that regulation of telomere length is very complex and involves multiple processes. For example, the "end replication problem" during DNA replication as well as oxidative stress are responsible for the shortening of telomeres. In contrast, telomerase activity can potentially counteract telomere shortening when it is able to access and interact with telomeres. However, while highly active during development and in cancer cells, the enzyme is down-regulated in most human somatic cells with a few exceptions such as human lymphocytes. In addition, telomeres can be transcribed, and the transcription products called TERRA are involved in telomere length regulation.Thus, telomere length and their integrity are regulated at many different levels, and we only start to understand this process under conditions of increased oxidative stress, inflammation and during diseases as well as the ageing process.This chapter aims to describe our current state of knowledge on telomeres and telomerase and their regulation in order to better understand their role for the ageing process.
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18
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Alibardi L. Ultrastructural immunolocalization of telomerase and hyaluronate in migrating keratinocytes in a case of oro-pharyngeal squamous cancer. Pathol Res Pract 2018; 215:215-221. [PMID: 30409452 DOI: 10.1016/j.prp.2018.10.039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 10/28/2018] [Accepted: 10/31/2018] [Indexed: 10/27/2022]
Abstract
The ultrastructural immunolocalization of telomerase and hyaluronate has been studied in a case of oropharyngeal squamous carcinoma. Immunofluorescence shows that telomerase immunolabeling is present in the cytoplasm and in nuclei of some keratinocytes during their migration into the underlying connective tissue. The electron microscope shows that the nuclear localization of telomerase mainly occurs in the large nucleoli and in likely Cajal bodies, the sites of assembling and maturation of proteins forming the telomerase complex. Aside ribosomes, the nucleolus has a role in the biosynthesis of this reverse transcriptase during cell proliferation in normal tissues and in tumors. The cytoplasmic labeling for telomerase is frequently associated with an irregular network of keratin bundles but the significance of this observation is unclear. Hyaluronate, detected through ultrastructural immunolocalization of a hyaluronate binding protein, is abundant mostly along the cell membrane of the detaching basal keratinocytes during epithelial mesenchymal transition. A coat of hyaluronate surrounds the free keratinocytes of the squamous epithelium and is present around the connective cells present underneath. The study supports the hypothesis that hyaluronate forms a pathway along which epithelial cells can migrate during epidermal mesenchymal transition and may also shield cancer cells from immune cells.
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Affiliation(s)
- Lorenzo Alibardi
- Comparative Histolab Padova and Department of Biology of University of Bologna, Italy
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19
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Abstract
PURPOSE OF REVIEW The activation of telomere maintenance pathways has long been regarded as a key hallmark of cancer and this has propelled the development of novel inhibitors of telomerase. In this review, we detail the background biology on telomere maintenance in health and disease, then concentrate on the recent preclinical and clinical development behind targeting telomerase in blood cancers. RECENT FINDINGS Preclinical and clinical studies have shown that imetelstat, a competitive inhibitor of telomerase, has activity in certain hematologic malignancies, in particular the myeloproliferative neoplasms and acute myeloid leukemia. SUMMARY Telomerase inhibition has shown remarkable efficacy in myeloid malignancies, and current and future preclinical and clinical studies are necessary to comprehensively investigate its underlying mechanism of action. Future work should identify the potential genetic susceptibilities to telomerase inhibition therapy, and evaluate rational combinations of telomerase inhibitors with chemotherapy and other novel agents. Robust preclinical evaluation is essential to best translate these new agents successfully into our clinical treatment algorithm for myeloid and other blood cancers.
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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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Liang H, Chen X, Yin Q, Ruan D, Zhao X, Zhang C, McNutt MA, Yin Y. PTENβ is an alternatively translated isoform of PTEN that regulates rDNA transcription. Nat Commun 2017; 8:14771. [PMID: 28332494 PMCID: PMC5376652 DOI: 10.1038/ncomms14771] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Accepted: 01/27/2017] [Indexed: 12/17/2022] Open
Abstract
PTEN is a critical tumour suppressor that is frequently mutated in human cancer. We have previously identified a CUG initiated PTEN isoform designated PTENα, which functions in mitochondrial bioenergetics. Here we report the identification of another N-terminal extended PTEN isoform, designated PTENβ. PTENβ translation is initiated from an AUU codon upstream of and in-frame with the AUG initiation sequence for canonical PTEN. We show that the Kozak context and a downstream hairpin structure are critical for this alternative initiation. PTENβ localizes predominantly in the nucleolus, and physically associates with and dephosphorylates nucleolin, which is a multifunctional nucleolar phosphoprotein. Disruption of PTENβ alters rDNA transcription and promotes ribosomal biogenesis, and this effect can be reversed by re-introduction of PTENβ. Our data show that PTENβ regulates pre-rRNA synthesis and cellular proliferation. These results demonstrate the complexity of the PTEN protein family and the diversity of its functions.
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Affiliation(s)
- Hui Liang
- Institute of Systems Biomedicine, Department of Pathology, School of Basic Medicine, Beijing Key Laboratory of Tumor Systems Biology, Peking-Tsinghua Center of Life Sciences, Peking University Health Science Center, Beijing 100191, China
| | - Xi Chen
- Institute of Systems Biomedicine, Department of Pathology, School of Basic Medicine, Beijing Key Laboratory of Tumor Systems Biology, Peking-Tsinghua Center of Life Sciences, Peking University Health Science Center, Beijing 100191, China
| | - Qi Yin
- Institute of Systems Biomedicine, Department of Pathology, School of Basic Medicine, Beijing Key Laboratory of Tumor Systems Biology, Peking-Tsinghua Center of Life Sciences, Peking University Health Science Center, Beijing 100191, China
| | - Danhui Ruan
- Institute of Systems Biomedicine, Department of Pathology, School of Basic Medicine, Beijing Key Laboratory of Tumor Systems Biology, Peking-Tsinghua Center of Life Sciences, Peking University Health Science Center, Beijing 100191, China
| | - Xuyang Zhao
- Institute of Systems Biomedicine, Department of Pathology, School of Basic Medicine, Beijing Key Laboratory of Tumor Systems Biology, Peking-Tsinghua Center of Life Sciences, Peking University Health Science Center, Beijing 100191, China
| | - Cong Zhang
- Institute of Systems Biomedicine, Department of Pathology, School of Basic Medicine, Beijing Key Laboratory of Tumor Systems Biology, Peking-Tsinghua Center of Life Sciences, Peking University Health Science Center, Beijing 100191, China
| | - Michael A. McNutt
- Institute of Systems Biomedicine, Department of Pathology, School of Basic Medicine, Beijing Key Laboratory of Tumor Systems Biology, Peking-Tsinghua Center of Life Sciences, Peking University Health Science Center, Beijing 100191, China
| | - Yuxin Yin
- Institute of Systems Biomedicine, Department of Pathology, School of Basic Medicine, Beijing Key Laboratory of Tumor Systems Biology, Peking-Tsinghua Center of Life Sciences, Peking University Health Science Center, Beijing 100191, China
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22
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Kotsantis P, Silva LM, Irmscher S, Jones RM, Folkes L, Gromak N, Petermann E. Increased global transcription activity as a mechanism of replication stress in cancer. Nat Commun 2016; 7:13087. [PMID: 27725641 PMCID: PMC5062618 DOI: 10.1038/ncomms13087] [Citation(s) in RCA: 201] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Accepted: 08/31/2016] [Indexed: 12/28/2022] Open
Abstract
Cancer is a disease associated with genomic instability that often results from oncogene activation. This in turn leads to hyperproliferation and replication stress. However, the molecular mechanisms that underlie oncogene-induced replication stress are still poorly understood. Oncogenes such as HRASV12 promote proliferation by upregulating general transcription factors to stimulate RNA synthesis. Here we investigate whether this increase in transcription underlies oncogene-induced replication stress. We show that in cells overexpressing HRASV12, elevated expression of the general transcription factor TATA-box binding protein (TBP) leads to increased RNA synthesis, which together with R-loop accumulation results in replication fork slowing and DNA damage. Furthermore, overexpression of TBP alone causes the hallmarks of oncogene-induced replication stress, including replication fork slowing, DNA damage and senescence. Consequently, we reveal that increased transcription can be a mechanism of oncogene-induced DNA damage, providing a molecular link between upregulation of the transcription machinery and genomic instability in cancer. Cancer cells proliferate at high rates and incur replication stress. Here, the authors show that this can be the consequence of oncogene-induced higher transcriptional activity, which, through increased RNA synthesis and R-loop accumulation, results in replication fork slowing and DNA damage.
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Affiliation(s)
- Panagiotis Kotsantis
- Institute of Cancer and Genomic Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Lara Marques Silva
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Sarah Irmscher
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Rebecca M Jones
- Institute of Cancer and Genomic Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Lisa Folkes
- Department of Oncology, CRUK/MRC Oxford Institute for Radiation Oncology, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford OX3 7DQ, UK
| | - Natalia Gromak
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Eva Petermann
- Institute of Cancer and Genomic Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
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23
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Trinkle-Mulcahy L, Sleeman JE. The Cajal body and the nucleolus: "In a relationship" or "It's complicated"? RNA Biol 2016; 14:739-751. [PMID: 27661468 DOI: 10.1080/15476286.2016.1236169] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
From their initial identification as 'nucleolar accessory bodies' more than a century ago, the relationship between Cajal bodies and nucleoli has been a subject of interest and controversy. In this review, we seek to place recent developments in the understanding of the physical and functional relationships between the 2 structures in the context of historical observations. Biophysical models of nuclear body formation, the molecular nature of CB/nucleolus interactions and the increasing list of joint roles for CBs and nucleoli, predominantly in assembling ribonucleoprotein (RNP) complexes, are discussed.
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Affiliation(s)
- Laura Trinkle-Mulcahy
- a Department of Cellular and Molecular Medicine , Ottawa Institute of Systems Biology, University of Ottawa , Ottawa , ON , Canada
| | - Judith E Sleeman
- b BSRC Complex, School of Biology, University of St Andrews , UK
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24
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Khattar E, Kumar P, Liu CY, Akıncılar SC, Raju A, Lakshmanan M, Maury JJP, Qiang Y, Li S, Tan EY, Hui KM, Shi M, Loh YH, Tergaonkar V. Telomerase reverse transcriptase promotes cancer cell proliferation by augmenting tRNA expression. J Clin Invest 2016; 126:4045-4060. [PMID: 27643433 DOI: 10.1172/jci86042] [Citation(s) in RCA: 92] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 08/11/2016] [Indexed: 12/13/2022] Open
Abstract
Transcriptional reactivation of telomerase reverse transcriptase (TERT) reconstitutes telomerase activity in the majority of human cancers. Here, we found that ectopic TERT expression increases cell proliferation, while acute reductions in TERT levels lead to a dramatic loss of proliferation without any change in telomere length, suggesting that the effects of TERT could be telomere independent. We observed that TERT determines the growth rate of cancer cells by directly regulating global protein synthesis independently of its catalytic activity. Genome-wide TERT binding across 5 cancer cell lines and 2 embryonic stem cell lines revealed that endogenous TERT, driven by mutant promoters or oncogenes, directly associates with the RNA polymerase III (pol III) subunit RPC32 and enhances its recruitment to chromatin, resulting in increased RNA pol III occupancy and tRNA expression in cancers. TERT-deficient mice displayed marked delays in polyomavirus middle T oncogene-induced (PyMT-induced) mammary tumorigenesis, increased survival, and reductions in tRNA levels. Ectopic expression of either RPC32 or TERT restored tRNA levels and proliferation defects in TERT-depleted cells. Finally, we determined that levels of TERT and tRNA correlated in breast and liver cancer samples. Together, these data suggest the existence of a unifying mechanism by which TERT enhances translation in cells to regulate cancer cell proliferation.
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MESH Headings
- Animals
- Cell Line, Tumor
- Cell Proliferation
- Cell Transformation, Neoplastic/metabolism
- Female
- Gene Expression Regulation, Neoplastic
- HEK293 Cells
- Humans
- Mammary Neoplasms, Experimental/enzymology
- Mammary Neoplasms, Experimental/pathology
- Mice, 129 Strain
- Mice, Inbred C57BL
- Mice, Inbred NOD
- Mice, Knockout
- Mice, SCID
- Neoplasm Transplantation
- Promoter Regions, Genetic
- Protein Binding
- Protein Biosynthesis
- Protein Interaction Domains and Motifs
- RNA Polymerase III/metabolism
- RNA, Transfer/genetics
- RNA, Transfer/metabolism
- Telomerase/physiology
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25
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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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26
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Telomerase: The Devil Inside. Genes (Basel) 2016; 7:genes7080043. [PMID: 27483324 PMCID: PMC4999831 DOI: 10.3390/genes7080043] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 07/23/2016] [Accepted: 07/25/2016] [Indexed: 01/04/2023] Open
Abstract
High telomerase activity is detected in nearly all human cancers but most human cells are devoid of telomerase activity. There is well-documented evidence that reactivation of telomerase occurs during cellular transformation. In humans, tumors can rely in reactivation of telomerase or originate in a telomerase positive stem/progenitor cell, or rely in alternative lengthening of telomeres, a telomerase-independent telomere-length maintenance mechanism. In this review, we will focus on the telomerase positive tumors. In this context, the recent findings that telomerase reverse transcriptase (TERT) promoter mutations represent the most common non-coding mutations in human cancer have flared up the long-standing discussion whether cancer originates from telomerase positive stem cells or telomerase reactivation is a final step in cellular transformation. Here, we will discuss the pros and cons of both concepts in the context of telomere length-dependent and telomere length-independent functions of telomerase. Together, these observations may provoke a re-evaluation of telomere and telomerase based therapies, both in telomerase inhibition for cancer therapy and telomerase activation for tissue regeneration and anti-ageing strategies.
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27
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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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28
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Meena JK, Cerutti A, Beichler C, Morita Y, Bruhn C, Kumar M, Kraus JM, Speicher MR, Wang ZQ, Kestler HA, d'Adda di Fagagna F, Günes C, Rudolph KL. Telomerase abrogates aneuploidy-induced telomere replication stress, senescence and cell depletion. EMBO J 2015; 34:1371-84. [PMID: 25820263 PMCID: PMC4491997 DOI: 10.15252/embj.201490070] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Revised: 03/03/2015] [Accepted: 03/04/2015] [Indexed: 11/09/2022] Open
Abstract
The causal role of aneuploidy in cancer initiation remains under debate since mutations of euploidy-controlling genes reduce cell fitness but aneuploidy strongly associates with human cancers. Telomerase activation allows immortal growth by stabilizing telomere length, but its role in aneuploidy survival has not been characterized. Here, we analyze the response of primary human cells and murine hematopoietic stem cells (HSCs) to aneuploidy induction and the role of telomeres and the telomerase in this process. The study shows that aneuploidy induces replication stress at telomeres leading to telomeric DNA damage and p53 activation. This results in p53/Rb-dependent, premature senescence of human fibroblast, and in the depletion of hematopoietic cells in telomerase-deficient mice. Endogenous telomerase expression in HSCs and enforced expression of telomerase in human fibroblasts are sufficient to abrogate aneuploidy-induced replication stress at telomeres and the consequent induction of premature senescence and hematopoietic cell depletion. Together, these results identify telomerase as an aneuploidy survival factor in mammalian cells based on its capacity to alleviate telomere replication stress in response to aneuploidy induction.
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Affiliation(s)
- Jitendra K Meena
- Leibniz Institute of Age Research, Fritz Lipmann Institute e.V., Jena, Germany
| | - Aurora Cerutti
- IFOM Foundation-FIRC Institute of Molecular Oncology Foundation, Milan, Italy
| | | | - Yohei Morita
- Leibniz Institute of Age Research, Fritz Lipmann Institute e.V., Jena, Germany
| | - Christopher Bruhn
- Leibniz Institute of Age Research, Fritz Lipmann Institute e.V., Jena, Germany
| | - Mukesh Kumar
- Institute of Experimental Cancer Research, University of Ulm, Ulm, Germany
| | - Johann M Kraus
- Medical Systems Biology Unit, Ulm University, Ulm, Germany
| | | | - Zhao-Qi Wang
- Leibniz Institute of Age Research, Fritz Lipmann Institute e.V., Jena, Germany
| | - Hans A Kestler
- Leibniz Institute of Age Research, Fritz Lipmann Institute e.V., Jena, Germany Medical Systems Biology Unit, Ulm University, Ulm, Germany
| | - Fabrizio d'Adda di Fagagna
- IFOM Foundation-FIRC Institute of Molecular Oncology Foundation, Milan, Italy Istituto di Genetica Molecolare, Consiglio Nazionale delle Ricerche, Pavia, Italy
| | - Cagatay Günes
- Leibniz Institute of Age Research, Fritz Lipmann Institute e.V., Jena, Germany
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29
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Koh CM, Khattar E, Leow SC, Liu CY, Muller J, Ang WX, Li Y, Franzoso G, Li S, Guccione E, Tergaonkar V. Telomerase regulates MYC-driven oncogenesis independent of its reverse transcriptase activity. J Clin Invest 2015; 125:2109-22. [PMID: 25893605 PMCID: PMC4463203 DOI: 10.1172/jci79134] [Citation(s) in RCA: 122] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Accepted: 03/12/2015] [Indexed: 12/25/2022] Open
Abstract
Constitutively active MYC and reactivated telomerase often coexist in cancers. While reactivation of telomerase is thought to be essential for replicative immortality, MYC, in conjunction with cofactors, confers several growth advantages to cancer cells. It is known that the reactivation of TERT, the catalytic subunit of telomerase, is limiting for reconstituting telomerase activity in tumors. However, while reactivation of TERT has been functionally linked to the acquisition of several "hallmarks of cancer" in tumors, the molecular mechanisms by which this occurs and whether these mechanisms are distinct from the role of telomerase on telomeres is not clear. Here, we demonstrated that first-generation TERT-null mice, unlike Terc-null mice, show delayed onset of MYC-induced lymphomagenesis. We further determined that TERT is a regulator of MYC stability in cancer. TERT stabilized MYC levels on chromatin, contributing to either activation or repression of its target genes. TERT regulated MYC ubiquitination and proteasomal degradation, and this effect of TERT was independent of its reverse transcriptase activity and role in telomere elongation. Based on these data, we conclude that reactivation of TERT, a direct transcriptional MYC target in tumors, provides a feed-forward mechanism to potentiate MYC-dependent oncogenesis.
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MESH Headings
- Animals
- Cell Line, Tumor
- Cell Transformation, Neoplastic/genetics
- Enzyme Activation
- Feedback, Physiological
- Gene Expression Regulation, Neoplastic/genetics
- Genes, myc
- Glycogen Synthase Kinase 3/physiology
- Glycogen Synthase Kinase 3 beta
- Heterografts
- Humans
- Lymphoma, Non-Hodgkin/pathology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Neoplasm Proteins/genetics
- Neoplasm Proteins/metabolism
- Neoplasm Proteins/physiology
- Neoplasm Transplantation
- Phosphorylation
- Promoter Regions, Genetic
- Protein Processing, Post-Translational
- Protein Stability
- Proto-Oncogene Proteins c-myc/genetics
- Proto-Oncogene Proteins c-myc/metabolism
- Proto-Oncogene Proteins c-myc/physiology
- RNA/genetics
- RNA/physiology
- RNA Interference
- Telomerase/deficiency
- Telomerase/genetics
- Telomerase/physiology
- Telomere Homeostasis/genetics
- Time Factors
- Transcription, Genetic
- Ubiquitination
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Affiliation(s)
- Cheryl M. Koh
- Division of Cancer Genetics and Therapeutics, Laboratory of Methyltransferases in Development and Disease, and
| | - Ekta Khattar
- Division of Cancer Genetics and Therapeutics, Laboratory of NF-κB Signaling, Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore
| | - Shi Chi Leow
- Division of Cancer Genetics and Therapeutics, Laboratory of NF-κB Signaling, Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore
| | - Chia Yi Liu
- Division of Cancer Genetics and Therapeutics, Laboratory of NF-κB Signaling, Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore
| | - Julius Muller
- Division of Cancer Genetics and Therapeutics, Laboratory of Methyltransferases in Development and Disease, and
| | - Wei Xia Ang
- Division of Cancer Genetics and Therapeutics, Laboratory of Methyltransferases in Development and Disease, and
| | - Yinghui Li
- Division of Cancer Genetics and Therapeutics, Laboratory of NF-κB Signaling, Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore
| | - Guido Franzoso
- Department of Medicine, Imperial College London, London, United Kingdom
| | - Shang Li
- Program in Cancer and Stem Cell Biology, Duke-NUS Graduate Medical School, Singapore
- Department of Physiology and
| | - Ernesto Guccione
- Division of Cancer Genetics and Therapeutics, Laboratory of Methyltransferases in Development and Disease, and
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Vinay Tergaonkar
- Division of Cancer Genetics and Therapeutics, Laboratory of NF-κB Signaling, Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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30
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Abstract
Telomeres form protective caps at the ends of linear chromosomes to prevent nucleolytic degradation, end-to-end fusion, irregular recombination, and chromosomal instability. Telomeres are composed of repetitive DNA sequences (TTAGGG)n in humans, that are bound by specialized telomere binding proteins. Telomeres lose capping function in response to telomere shortening, which occurs during each division of cells that lack telomerase activity-the enzyme that can synthesize telomeres de novo. Telomeres have a dual role in cancer: telomere shortening can lead to induction of chromosomal instability and to the initiation of tumors, however, initiated tumors need to reactivate telomerase in order to stabilize chromosomes and to gain immortal growth capacity. In this review, we summarize current knowledge on the role of telomeres in the maintenance of chromosomal stability and carcinogenesis.
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31
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Abstract
Leukemia stem cells (LSCs), featuring unlimited self-renewal capacity and chemoresistance, are critical cellular targets for new treatments to improve outcomes for acute myeloid leukemia (AML). In this issue of Cell Stem Cell, Bruedigam et al. (2014) demonstrate that inhibition of telomerase is damaging to LSCs and may represent a promising therapeutic approach in AML.
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Affiliation(s)
- Ya-Huei Kuo
- Division of Hematopoietic Stem Cell and Leukemia Research, Beckman Research Institute of the City of Hope, Duarte, CA 91010, USA.
| | - Ravi Bhatia
- Division of Hematopoietic Stem Cell and Leukemia Research, Beckman Research Institute of the City of Hope, Duarte, CA 91010, USA.
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32
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Murphy RP, Kelley E, Rogers SA, Sullivan MO, Epps TH. Unlocking Chain Exchange in Highly Amphiphilic Block Polymer Micellar Systems: Influence of Agitation. ACS Macro Lett 2014; 3:1106-1111. [PMID: 25642383 PMCID: PMC4307907 DOI: 10.1021/mz500435d] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Accepted: 10/07/2014] [Indexed: 12/22/2022]
Abstract
Chain exchange between block polymer micelles in highly selective solvents, such as water, is well-known to be arrested under quiescent conditions, yet this work demonstrates that simple agitation methods can induce rapid chain exchange in these solvents. Aqueous solutions containing either pure poly(butadiene-b-ethylene oxide) or pure poly(butadiene-b-ethylene oxide-d4) micelles were combined and then subjected to agitation by vortex mixing, concentric cylinder Couette flow, or nitrogen gas sparging. Subsequently, the extent of chain exchange between micelles was quantified using small angle neutron scattering. Rapid vortex mixing induced chain exchange within minutes, as evidenced by a monotonic decrease in scattered intensity, whereas Couette flow and sparging did not lead to measurable chain exchange over the examined time scale of hours. The linear kinetics with respect to agitation time suggested a surface-limited exchange process at the air-water interface. These findings demonstrate the strong influence of processing conditions on block polymer solution assemblies.
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Affiliation(s)
| | | | - Simon A. Rogers
- Department
of Chemical and
Biomolecular Engineering, University of
Delaware, 150 Academy
Street, Newark, Delaware 19716, United States
| | - Millicent O. Sullivan
- Department
of Chemical and
Biomolecular Engineering, University of
Delaware, 150 Academy
Street, Newark, Delaware 19716, United States
| | - Thomas H. Epps
- Department
of Chemical and
Biomolecular Engineering, University of
Delaware, 150 Academy
Street, Newark, Delaware 19716, United States
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