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Hakobyan M, Binder H, Arakelyan A. Pan-cancer analysis of telomere maintenance mechanisms. J Biol Chem 2024; 300:107392. [PMID: 38763334 DOI: 10.1016/j.jbc.2024.107392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Revised: 04/28/2024] [Accepted: 05/13/2024] [Indexed: 05/21/2024] Open
Abstract
Telomeres, protective caps at chromosome ends, maintain genomic stability and control cell lifespan. Dysregulated telomere maintenance mechanisms (TMMs) are cancer hallmarks, enabling unchecked cell proliferation. We conducted a pan-cancer evaluation of TMM using RNA sequencing data from The Cancer Genome Atlas for 33 different cancer types and analyzed the activities of telomerase-dependent (TEL) and alternative lengthening of telomeres (ALT) TMM pathways in detail. To further characterize the TMM profiles, we categorized the tumors based on their ALT and TEL TMM pathway activities into five major phenotypes: ALT high TEL low, ALT low TEL low, ALT middle TEL middle, ALT high TEL high, and ALT low TEL high. These phenotypes refer to variations in telomere maintenance strategies, shedding light on the heterogeneous nature of telomere regulation in cancer. Moreover, we investigated the clinical implications of TMM phenotypes by examining their associations with clinical characteristics and patient outcomes. Specific TMM profiles were linked to specific survival patterns, emphasizing the potential of TMM profiling as a prognostic indicator and aiding in personalized cancer treatment strategies. Gene ontology analysis of the TMM phenotypes unveiled enriched biological processes associated with cell cycle regulation (both TEL and ALT), DNA replication (TEL), and chromosome dynamics (ALT) showing that telomere maintenance is tightly intertwined with cellular processes governing proliferation and genomic stability. Overall, our study provides an overview of the complexity of transcriptional regulation of telomere maintenance mechanisms in cancer.
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Affiliation(s)
- Meline Hakobyan
- Bioinformatics Group, Institute of Molecular Biology NAS RA, Yerevan, Armenia.
| | - Hans Binder
- Interdisciplinary Centre for Bioinformatics, University of Leipzig, Leipzig, Germany; Armenian Bioinformatics Institute, Yerevan, Armenia
| | - Arsen Arakelyan
- Bioinformatics Group, Institute of Molecular Biology NAS RA, Yerevan, Armenia
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Sung JY, Cheong JH. Pan-Cancer Analysis of Clinical Relevance via Telomere Maintenance Mechanism. Int J Mol Sci 2021; 22:ijms222011101. [PMID: 34681758 PMCID: PMC8538844 DOI: 10.3390/ijms222011101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 10/04/2021] [Accepted: 10/13/2021] [Indexed: 12/24/2022] Open
Abstract
Understanding the telomere maintenance mechanism (TMM) in immortal cancer cells is vital for TMM-targeted therapies in clinical settings. In this study, we classified four telomere maintenance mechanisms into telomerase, ALT, telomerase + ALT, and non-defined telomere maintenance mechanism (NDTMM) across 31 cancer types using 10,704 transcriptomic datasets from The Cancer Genome Atlas. Our results demonstrated that approximately 50% of the total cohort displayed ALT activity with high telomerase activity in most cancer types. We confirmed significant patient prognoses according to distinct TMMs in six cancer types: adrenocortical carcinoma (ACC), PAAD, HNSC, SARC, GBM, and metastatic cancer. Patients with metastasis had a poor prognosis in the ALT group (p < 0.006) subjected to RAS protein signal transduction. Glioblastoma patients had poor prognosis in NDTMM (p < 0.0043) and showed high levels of myeloid leukocyte activation. Pancreatic adenocarcinoma (p < 0.04) and head and neck squamous cell carcinoma (p < 0.046) patients had a good prognosis in the ALT group with high immune cell activation. Furthermore, we showed that master transcriptional regulators might affect the selection of the TMM pathway and explained why different telomere maintenance mechanisms exist. Furthermore, they can be used to segregate patients and predict responders to different TMM-targeted therapeutics.
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Affiliation(s)
- Ji-Yong Sung
- Department of Biomedical Systems Informatics, Yonsei University College of Medicine, Seoul 03722, Korea;
- Department of Laboratory Medicine, Yonsei University College of Medicine, Seoul 03722, Korea
| | - Jae-Ho Cheong
- Department of Biomedical Systems Informatics, Yonsei University College of Medicine, Seoul 03722, Korea;
- Department of Surgery, Yonsei University College of Medicine, Seoul 03722, Korea
- Yonsei Biomedical Research Institute, Yonsei University College of Medicine, Seoul 03722, Korea
- Department of Biochemistry & Molecular Biology, Yonsei University College of Medicine, Seoul 03722, Korea
- Department of Research & Development, VeraVerse Inc., Seoul 03722, Korea
- Correspondence:
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Long Leukocyte Telomere Length Is Associated with Increased Risks of Soft Tissue Sarcoma: A Mendelian Randomization Study. Cancers (Basel) 2020; 12:cancers12030594. [PMID: 32150919 PMCID: PMC7139681 DOI: 10.3390/cancers12030594] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 02/24/2020] [Accepted: 03/03/2020] [Indexed: 12/12/2022] Open
Abstract
Background: Leukocyte telomere length (LTL) has been associated with the risks of several cancers in observational studies. Mendelian randomization (MR) studies, using genetic variants as instrumental variables, have also shown associations of genetically predicted LTL with cancer risks. In this study, we performed the first MR analysis on soft tissue sarcoma (STS) to investigate the causal relationship between LTL and the risk of STS. Methods: Genotypes from eleven LTL-associated single nucleotide polymorphisms (SNPs) in 821 STS cases and 851 cancer-free controls were aggregated into a weighted genetic risk score (GRS) to predict LTL. Multivariate logistic regression was used to assess the association of STS risk with individual SNPs and aggregated GRS. Results: Four SNPs displayed evidence for an individual association between long LTL-conferring allele and increased STS risk: rs7675998 (odds ratio (OR) = 1.21, 95% confidence interval (CI) = 1.02–1.43), rs9420907 (OR = 1.31, 95% CI = 1.08–1.59), rs8105767 (OR = 1.18, 95% CI = 1.02–1.37), and rs412658 (OR = 1.18, 95% CI = 1.02–1.36). Moreover, longer genetically predicted LTL, calculated as GRS, was strongly associated with an increased risk of STS (OR = 1.44, 95% CI = 1.18–1.75, p < 0.001), and there was a significant dose-response association (p for trend <0.001 in tertile and quartile analyses). The association of longer LTL with higher STS risk was more evident in women than in men. In stratified analyses by major STS subtypes, longer LTL was significantly associated with higher risks of leiomyosarcoma and gastrointestinal stromal tumors. Conclusions: Longer LTL is associated with increased risks of STS.
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M'kacher R, Cuceu C, Al Jawhari M, Morat L, Frenzel M, Shim G, Lenain A, Hempel WM, Junker S, Girinsky T, Colicchio B, Dieterlen A, Heidingsfelder L, Borie C, Oudrhiri N, Bennaceur-Griscelli A, Moralès O, Renaud S, Van de Wyngaert Z, Jeandidier E, Delhem N, Carde P. The Transition between Telomerase and ALT Mechanisms in Hodgkin Lymphoma and Its Predictive Value in Clinical Outcomes. Cancers (Basel) 2018; 10:E169. [PMID: 29848986 PMCID: PMC6025489 DOI: 10.3390/cancers10060169] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Revised: 05/18/2018] [Accepted: 05/25/2018] [Indexed: 11/16/2022] Open
Abstract
Background: We analyzed telomere maintenance mechanisms (TMMs) in lymph node samples from HL patients treated with standard therapy. The TMMs correlated with clinical outcomes of patients. Materials and Methods: Lymph node biopsies obtained from 38 HL patients and 24 patients with lymphadenitis were included in this study. Seven HL cell lines were used as in vitro models. Telomerase activity (TA) was assessed by TRAP assay and verified through hTERT immunofluorescence expression; alternative telomere lengthening (ALT) was also assessed, along with EBV status. Results: Both TA and ALT mechanisms were present in HL lymph nodes. Our findings were reproduced in HL cell lines. The highest levels of TA were expressed in CD30-/CD15- cells. Small cells were identified with ALT and TA. Hodgkin and Reed Sternberg cells contained high levels of PML bodies, but had very low hTERT expression. There was a significant correlation between overall survival (p < 10-3), event-free survival (p < 10-4), and freedom from progression (p < 10-3) and the presence of an ALT profile in lymph nodes of EBV+ patients. Conclusion: The presence of both types of TMMs in HL lymph nodes and in HL cell lines has not previously been reported. TMMs correlate with the treatment outcome of EBV+ HL patients.
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Affiliation(s)
- Radhia M'kacher
- Laboratoire de Radiobiologie et d'Oncologie, IRCM/DSV/CEA, 92265 Fontenay aux Roses, France.
- Cell Environment, DNA Damages R&D, Oncology Section, 75020 Paris, France.
| | - Corina Cuceu
- Laboratoire de Radiobiologie et d'Oncologie, IRCM/DSV/CEA, 92265 Fontenay aux Roses, France.
| | - Mustafa Al Jawhari
- Laboratoire de Radiobiologie et d'Oncologie, IRCM/DSV/CEA, 92265 Fontenay aux Roses, France.
| | - Luc Morat
- Laboratoire de Radiobiologie et d'Oncologie, IRCM/DSV/CEA, 92265 Fontenay aux Roses, France.
| | - Monika Frenzel
- Laboratoire de Radiobiologie et d'Oncologie, IRCM/DSV/CEA, 92265 Fontenay aux Roses, France.
| | - Grace Shim
- Laboratoire de Radiobiologie et d'Oncologie, IRCM/DSV/CEA, 92265 Fontenay aux Roses, France.
| | - Aude Lenain
- Laboratoire de Radiobiologie et d'Oncologie, IRCM/DSV/CEA, 92265 Fontenay aux Roses, France.
| | - William M Hempel
- Laboratoire de Radiobiologie et d'Oncologie, IRCM/DSV/CEA, 92265 Fontenay aux Roses, France.
| | - Steffen Junker
- Institute of Biomedicine, University of Aarhus, DK-8000 Aarhus C, Denmark.
| | - Theodore Girinsky
- Department of Radiation Therapy, Gustave Roussy Cancer Campus, 94808 Villejuif, France.
| | - Bruno Colicchio
- IRIMAS, Institut de Recherche en Informatique, Mathématiques, Automatique et Signal, Université de Haute-Alsace, 68093 Mulhouse, France.
| | - Alain Dieterlen
- IRIMAS, Institut de Recherche en Informatique, Mathématiques, Automatique et Signal, Université de Haute-Alsace, 68093 Mulhouse, France.
| | | | - Claire Borie
- Université Paris Sud, Service d'hématologie moléculaire et cytogénétique Paul brousse CHU paris Sud, Inserm UMRS935, 94800 Villejuif, France.
| | - Noufissa Oudrhiri
- Université Paris Sud, Service d'hématologie moléculaire et cytogénétique Paul brousse CHU paris Sud, Inserm UMRS935, 94800 Villejuif, France.
| | - Annelise Bennaceur-Griscelli
- Université Paris Sud, Service d'hématologie moléculaire et cytogénétique Paul brousse CHU paris Sud, Inserm UMRS935, 94800 Villejuif, France.
| | - Olivier Moralès
- CNRS, Institut Pasteur de Lille, UMR 8161-Immunoregulation of Virus-induced Cancers Team, F-59000 Lille, France.
| | - Sarah Renaud
- CNRS, Institut Pasteur de Lille, UMR 8161-Immunoregulation of Virus-induced Cancers Team, F-59000 Lille, France.
| | - Zoé Van de Wyngaert
- CHRU Lille Service des Maladies du Sang, Hopital Huriez, 59000 Lille, France.
| | - Eric Jeandidier
- Service de génétique, Groupe hospitalier de la région de Mulhouse Sud-Alsace, 68093 Mulhouse, France.
| | - Nadira Delhem
- CNRS, Institut Pasteur de Lille, UMR 8161-Immunoregulation of Virus-induced Cancers Team, F-59000 Lille, France.
| | - Patrice Carde
- Department of Medicine, Gustave Roussy Cancer Campus, 94808 Villejuif, France.
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De Vitis M, Berardinelli F, Sgura A. Telomere Length Maintenance in Cancer: At the Crossroad between Telomerase and Alternative Lengthening of Telomeres (ALT). Int J Mol Sci 2018; 19:ijms19020606. [PMID: 29463031 PMCID: PMC5855828 DOI: 10.3390/ijms19020606] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2017] [Revised: 02/12/2018] [Accepted: 02/14/2018] [Indexed: 02/07/2023] Open
Abstract
Eukaryotic cells undergo continuous telomere shortening as a consequence of multiple rounds of replications. During tumorigenesis, cells have to acquire telomere DNA maintenance mechanisms (TMMs) in order to counteract telomere shortening, to preserve telomeres from DNA damage repair systems and to avoid telomere-mediated senescence and/or apoptosis. For this reason, telomere maintenance is an essential step in cancer progression. Most human tumors maintain their telomeres expressing telomerase, whereas a lower but significant proportion activates the alternative lengthening of telomeres (ALT) pathway. However, evidence about the coexistence of ALT and telomerase has been found both in vivo in the same cancer populations and in vitro in engineered cellular models, making the distinction between telomerase- and ALT-positive tumors elusive. Indeed, after the development of drugs able to target telomerase, the capability for some cancer cells to escape death, switching from telomerase to ALT, was highlighted. Unfortunately, to date, the mechanism underlying the possible switching or the coexistence of telomerase and ALT within the same cell or populations is not completely understood and different factors could be involved. In recent years, different studies have tried to shed light on the complex regulation network that controls the transition between the two TMMs, suggesting a role for embryonic cancer origin, epigenetic modifications, and specific genes activation—both in vivo and in vitro. In this review, we examine recent findings about the cancer-associated differential activation of the two known TMMs and the possible factors implicated in this process. Furthermore, some studies on cancers are also described that did not display any TMM.
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Affiliation(s)
- Marco De Vitis
- Department of Science, Roma Tre University, 00146 Rome, Italy.
| | | | - Antonella Sgura
- Department of Science, Roma Tre University, 00146 Rome, Italy.
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6
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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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7
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Abstract
Activation of a telomere maintenance mechanism (TMM) is permissive for replicative immortality and a hallmark of human cancer. While most cancers rely on reactivation of telomerase, a significant fraction utilizes the recombination dependent alternative lengthening of telomeres (ALT) pathway. ALT is enriched in tumors of mesenchymal origin, including those arising from bone, soft tissue, and the nervous system, and usually portends a poor prognosis. Recent insights into the mechanisms of ALT are uncovering novel avenues to exploit vulnerabilities and may facilitate clinical development of ALT detection assays and personalized treatment decisions based on TMM status. Treatments targeting ALT may hold promise for a broadly applicable therapeutic modality specific to mesenchymal lineage tumors, something that has thus far remained elusive.
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Affiliation(s)
- Robert L Dilley
- Departments of Cancer Biology and Pathology, Abramson Family Cancer Research Institute, Basser Research Center for BRCA, Perelman School of Medicine, University of Pennsylvania, 421 Curie Boulevard, Philadelphia, PA 19104, USA
| | - Roger A Greenberg
- Departments of Cancer Biology and Pathology, Abramson Family Cancer Research Institute, Basser Research Center for BRCA, Perelman School of Medicine, University of Pennsylvania, 421 Curie Boulevard, Philadelphia, PA 19104, USA
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Doloff JC, Waxman DJ. Adenoviral vectors for prodrug activation-based gene therapy for cancer. Anticancer Agents Med Chem 2014; 14:115-26. [PMID: 23869779 DOI: 10.2174/18715206113139990309] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Revised: 01/09/2013] [Accepted: 04/10/2013] [Indexed: 11/22/2022]
Abstract
Cancer cell heterogeneity is a common feature - both between patients diagnosed with the same cancer and within an individual patient's tumor - and leads to widely different response rates to cancer therapies and the potential for the emergence of drug resistance. Diverse therapeutic approaches have been developed to combat the complexity of cancer, including individual treatment modalities designed to target tumor heterogeneity. This review discusses adenoviral vectors and how they can be modified to replicate in a cancer-specific manner and deliver therapeutic genes under multi-tiered regulation to target tumor heterogeneity, including heterogeneity associated with cancer stem cell-like subpopulations. Strategies that allow for combination of prodrug-activation gene therapy with a novel replication-conditional, heterogeneous tumor-targeting adenovirus are discussed, as are the benefits of using adenoviral vectors as tumor-targeting oncolytic vectors. While the anticancer activity of many adenoviral vectors has been well established in preclinical studies, only limited successes have been achieved in the clinic, indicating a need for further improvements in activity, specificity, tumor cell delivery and avoidance of immunogenicity.
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Affiliation(s)
| | - David J Waxman
- Department of Cell and Molecular, Biology, Boston University, 5 Cummington Mall, Boston, MA 02215, USA.
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9
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Chilton WL, Marques FZ, West J, Kannourakis G, Berzins SP, O’Brien BJ, Charchar FJ. Acute exercise leads to regulation of telomere-associated genes and microRNA expression in immune cells. PLoS One 2014; 9:e92088. [PMID: 24752326 PMCID: PMC3994003 DOI: 10.1371/journal.pone.0092088] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Accepted: 02/17/2014] [Indexed: 01/05/2023] Open
Abstract
Telomeres are specialized nucleoprotein structures that protect chromosomal ends from degradation. These structures progressively shorten during cellular division and can signal replicative senescence below a critical length. Telomere length is predominantly maintained by the enzyme telomerase. Significant decreases in telomere length and telomerase activity are associated with a host of chronic diseases; conversely their maintenance underpins the optimal function of the adaptive immune system. Habitual physical activity is associated with longer leukocyte telomere length; however, the precise mechanisms are unclear. Potential hypotheses include regulation of telomeric gene transcription and/or microRNAs (miRNAs). We investigated the acute exercise-induced response of telomeric genes and miRNAs in twenty-two healthy males (mean age = 24.1±1.55 years). Participants undertook 30 minutes of treadmill running at 80% of peak oxygen uptake. Blood samples were taken before exercise, immediately post-exercise and 60 minutes post-exercise. Total RNA from white blood cells was submitted to miRNA arrays and telomere extension mRNA array. Results were individually validated in white blood cells and sorted T cell lymphocyte subsets using quantitative real-time PCR (qPCR). Telomerase reverse transcriptase (TERT) mRNA (P = 0.001) and sirtuin-6 (SIRT6) (P<0.05) mRNA expression were upregulated in white blood cells after exercise. Fifty-six miRNAs were also differentially regulated post-exercise (FDR <0.05). In silico analysis identified four miRNAs (miR-186, miR-181, miR-15a and miR-96) that potentially targeted telomeric gene mRNA. The four miRNAs exhibited significant upregulation 60 minutes post-exercise (P<0.001). Telomeric repeat binding factor 2, interacting protein (TERF2IP) was identified as a potential binding target for miR-186 and miR-96 and demonstrated concomitant downregulation (P<0.01) at the corresponding time point. Intense cardiorespiratory exercise was sufficient to differentially regulate key telomeric genes and miRNAs in white blood cells. These results may provide a mechanistic insight into telomere homeostasis and improved immune function and physical health.
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Affiliation(s)
- Warrick L. Chilton
- School of Health Sciences, Federation University Australia, Victoria, Australia
| | - Francine Z. Marques
- School of Health Sciences, Federation University Australia, Victoria, Australia
| | - Jenny West
- Fiona Elsey Cancer Research Institute, Ballarat, Victoria, Australia
| | | | - Stuart P. Berzins
- Fiona Elsey Cancer Research Institute, Ballarat, Victoria, Australia
| | - Brendan J. O’Brien
- School of Health Sciences, Federation University Australia, Victoria, Australia
| | - Fadi J. Charchar
- School of Health Sciences, Federation University Australia, Victoria, Australia
- * E-mail:
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10
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TERT promoter hotspot mutations are recurrent in myxoid liposarcomas but rare in other soft tissue sarcoma entities. JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2014; 33:33. [PMID: 24726063 PMCID: PMC4022359 DOI: 10.1186/1756-9966-33-33] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Accepted: 04/08/2014] [Indexed: 01/21/2023]
Abstract
Background Recently, recurrent point mutations in the telomerase reverse transcriptase (TERT) promoter region have been found in many human cancers, leading to a new transcription factor binding site, increased induction of TERT and subsequently to telomere maintenance. We determined the prevalence of TERT promoter mutations in soft tissue sarcomas of 341 patients comprising 16 entities and in 16 sarcoma cell lines covering 7 different soft tissue sarcoma types. Methods The sarcoma tissue samples were collected from the archives of the Institute of Pathology, University of Heidelberg and were composed of 39 myxoid liposarcomas (MLS), 61 dedifferentiated liposarcomas, 15 pleomorphic liposarcomas, 27 leiomyosarcomas, 25 synovial sarcomas (SS), 35 malignant peripheral nerve sheath tumors (MPNST), 40 undifferentiated pleomorphic sarcomas, 17 myxofibrosarcomas, 9 low grade fibromyxoid sarcomas, 10 cases of dermatofibrosarcoma protuberans, 31 solitary fibrous tumors (SFT), 8 extraskeletal myxoid chondrosarcomas, 9 angiosarcomas, 6 alveolar soft part sarcomas, 5 clear cell sarcomas and 4 epithelioid sarcomas. Sarcoma cell lines were obtained from the raising laboratories. A 193 bp fragment of the TERT promoter region covering the hot-spot mutations C228T and C250T was amplified, and direct sequencing of the PCR products was performed. Results TERT promoter mutations were detected in 36/341 sarcomas. They were highly recurrent in MLS (29/39; 74%) and were in the present MLS series not associated with the phenotype (myxoid vs. round cell variant), tumor grade, tumor site and patients’ median age or gender. In the remaining cases, TERT promoter mutations were found only in 7/302 sarcoma samples and confined to SFTs (4/31; 13%), MPNSTs (2/35; 6%), and SSs (1/25; 4%). Within the collection of sarcoma cell lines examined, TERT promoter mutations were detected in two MLS and in one of three MPNST cell lines. Conclusions TERT promoter mutations are frequent in MLSs including their round cell variants, representing the most prevalent mutation identified in this sarcoma entity to date, and in a minor fraction of SFTs, MPNSTs and SSs. The majority of sarcomas are devoid of TERT promoter hotspot mutations. These data suggest that telomere maintenance through increased expression of telomerase plays an important role in the pathogenesis especially of MLS.
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11
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Telomere length, c-myc and mad-1 expression could represent prognosis markers of myelodysplastic syndrome. Leuk Res 2013; 37:1538-44. [DOI: 10.1016/j.leukres.2013.07.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Accepted: 07/17/2013] [Indexed: 11/18/2022]
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12
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Shalaby T, Fiaschetti G, Nagasawa K, Shin-ya K, Baumgartner M, Grotzer M. G-quadruplexes as potential therapeutic targets for embryonal tumors. Molecules 2013; 18:12500-37. [PMID: 24152672 PMCID: PMC6269990 DOI: 10.3390/molecules181012500] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 09/18/2013] [Accepted: 09/25/2013] [Indexed: 12/27/2022] Open
Abstract
Embryonal tumors include a heterogeneous group of highly malignant neoplasms that primarily affect infants and children and are characterized by a high rate of mortality and treatment-related morbidity, hence improved therapies are clearly needed. G-quadruplexes are special secondary structures adopted in guanine (G)-rich DNA sequences that are often present in biologically important regions, e.g. at the end of telomeres and in the regulatory regions of oncogenes such as MYC. Owing to the significant roles that both telomeres and MYC play in cancer cell biology, G-quadruplexes have been viewed as emerging therapeutic targets in oncology and as tools for novel anticancer drug design. Several compounds that target these structures have shown promising anticancer activity in tumor xenograft models and some of them have entered Phase II clinical trials. In this review we examine approaches to DNA targeted cancer therapy, summarize the recent developments of G-quadruplex ligands as anticancer drugs and speculate on the future direction of such structures as a potential novel therapeutic strategy for embryonal tumors of the nervous system.
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Affiliation(s)
- Tarek Shalaby
- Division of Oncology, University Children's Hospital of Zurich, Zurich 8032, Switzerland.
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13
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Gocha ARS, Nuovo G, Iwenofu OH, Groden J. Human sarcomas are mosaic for telomerase-dependent and telomerase-independent telomere maintenance mechanisms: implications for telomere-based therapies. THE AMERICAN JOURNAL OF PATHOLOGY 2013; 182:41-8. [PMID: 23260199 DOI: 10.1016/j.ajpath.2012.10.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Revised: 09/11/2012] [Accepted: 10/02/2012] [Indexed: 11/17/2022]
Abstract
Telomere shortening necessitates that tumor cells activate a telomere maintenance mechanism (TMM) to support immortalization. Although most tumor cells activate expression of the enzyme telomerase, some cells elongate telomeres in a telomerase-independent manner, termed alternative lengthening of telomeres (ALT). Previous studies have evaluated the presence of telomerase or ALT mechanisms or both in a variety of tumor types. Our studies also show that TMMs are not mutually exclusive in some tumors. In contrast, our IHC analyses of human sarcomas identified a subset of tumors with some cells containing ALT-associated PML bodies, a hallmark of ALT, and separate cells expressing telomerase in the same tumor. By using a second set of human osteosarcomas, we merged IHC and biochemical analyses to characterize more fully the tumor TMM. The IHC data reveal the presence of both telomerase- and ALT-positive tumor cells in samples that demonstrate characteristics of both telomerase and ALT in biochemical assays. These assays, which measure telomere length and telomerase activity of tumor extracts, are conventionally used to classify tumor TMM. Our results suggest that TMM is not a single or perhaps static characteristic of some tumors and that TMM heterogeneity should be considered in tumor stratification. Furthermore, clinical interest in telomere-based therapies may necessitate accurate characterization of tumor TMM before treatment to maximize therapeutic efficacy.
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Affiliation(s)
- April R S Gocha
- Department of Molecular Virology, Immunology, and Medical Genetics, Ohio State University College of Medicine, Columbus, Ohio, USA
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Xie H, Wu X, Wang S, Chang D, Pollock RE, Lev D, Gu J. Long telomeres in peripheral blood leukocytes are associated with an increased risk of soft tissue sarcoma. Cancer 2013; 119:1885-91. [PMID: 23408253 DOI: 10.1002/cncr.27984] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Revised: 01/07/2013] [Accepted: 01/08/2013] [Indexed: 12/11/2022]
Abstract
BACKGROUND Human telomeres consisting of long, tandem repeats of the nucleotide sequence TTAGGG at the chromosome ends are essential for maintaining chromosomal stability. Previous epidemiologic studies have indicated that shorter telomere length in peripheral blood leukocytes (PBLs) is associated with the development of many cancers. However, the relation between PBL telomere length and the risk of soft tissue sarcoma (STS) has not been investigated. METHODS The relative telomere length (RTL) was determined in PBLs using real-time polymerase chain reaction in this case-control study. The study participants included 137 patients with histologically confirmed STS (cases) who had received no prior chemotherapy or radiotherapy and 137 healthy controls who were frequency-matched to cases on age, sex, and ethnicity. RESULTS Patients in the case group had significantly longer RTL than controls (1.46 ± 0.42 for cases vs 1.15 ± 0.39 for controls; P < .001). By using median RTL in the controls as a cutoff level, individuals who had long telomere length were associated with a significantly increased risk of STS compared with those who had short telomere length (adjusted odds ratio, 4.71; 95% confidence interval, 2.63-8.44). When participants were categorized further into 3 or 4 groups according to the tertile or quartile RTL values of healthy controls, a significant dose-response relation was observed between longer RTL and increased risks of STS. CONCLUSIONS The current results provided the first epidemiologic evidence that longer telomere length in PBLs is associated significantly with an increased risk of STS, potentially suggesting an important role for telomere maintenance in STS development.
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Affiliation(s)
- Hui Xie
- Department of Epidemiology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
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15
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Caenorhabditis elegans POT-2 telomere protein represses a mode of alternative lengthening of telomeres with normal telomere lengths. Proc Natl Acad Sci U S A 2012; 109:7805-10. [PMID: 22547822 DOI: 10.1073/pnas.1119191109] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Canonical telomere repeats at chromosome termini can be maintained by a telomerase-independent pathway termed alternative lengthening of telomeres (ALT). Human cancers that survive via ALT can exhibit long and heterogeneous telomeres, although many telomerase-negative tumors possess telomeres of normal length. Here, we report that Caenorhabditis elegans telomerase mutants that survived via ALT possessed either long or normal telomere lengths. Most ALT strains displayed end-to-end chromosome fusions, suggesting that critical telomere shortening occurred before or concomitant with ALT. ALT required the 9-1-1 DNA damage response complex and its clamp loader, HPR-17. Deficiency for the POT-2 telomere binding protein promoted ALT in telomerase mutants, overcame the requirement for the 9-1-1 complex in ALT, and promoted ALT with normal telomere lengths. We propose that telomerase-deficient human tumors with normal telomere lengths could represent a mode of ALT that is facilitated by telomere capping protein dysfunction.
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Matsuo T, Shimose S, Kubo T, Fujimori J, Yasunaga Y, Sugita T, Ochi M. Correlation between p38 mitogen-activated protein kinase and human telomerase reverse transcriptase in sarcomas. J Exp Clin Cancer Res 2012; 31:5. [PMID: 22243975 PMCID: PMC3296589 DOI: 10.1186/1756-9966-31-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Accepted: 01/16/2012] [Indexed: 11/27/2022] Open
Abstract
Background One of the major components of telomerase is the human telomerase reverse transcriptase (hTERT) as the catalytic protein. hTERT mRNA expression are reported to be associated with prognosis and tumor progression in several sarcomas. However, there is no clear understanding of the mechanisms of hTERT in human sarcomas. Recent studies have suggested that signals transmitted through p38 mitogen-activated protein kinase (MAPK) can increase or decrease hTERT transcription in human cells. The purpose of this study was to analyse the correlation between p38 MAPK and hTERT in sarcoma samples. Methods We investigated 36 soft tissue malignant fibrous histiocytomas (MFH), 24 liposarcomas (LS) and 9 bone MFH samples for hTERT and p38 MAPK expression. Quantitative detection of hTERT and p38 MAPK was performed by RT-PCR. Results There was a significant positive correlation between the values of hTERT and p38 MAPK in all samples (r = 0.445, p = 0.0001), soft tissue MFH (r = 0.352, p = 0.0352), LS (r = 0.704, p = 0.0001) and bone MFH samples (r = 0.802, p = 0.0093). Patients who had a higher than average expression of p38 MAPK had a significantly worse prognosis than other patients (p = 0.0036). Conclusions p38 MAPK may play a role in up-regulation of hTERT, and therefore, p38 MAPK may be a useful marker in the assessment of hTERT and patients' prognosis in sarcomas.
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Affiliation(s)
- Toshihiro Matsuo
- Department of Orthopaedic Surgery, National Hospital Organization Kure Medical Center and Chugoku Cancer Center: 3-1, Aoyamacho, Kure, Hiroshima, 7370023 Japan.
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Heaphy CM, de Wilde RF, Jiao Y, Klein AP, Edil BH, Shi C, Bettegowda C, Rodriguez FJ, Eberhart CG, Hebbar S, Offerhaus GJ, McLendon R, Rasheed BA, He Y, Yan H, Bigner DD, Oba-Shinjo SM, Marie SKN, Riggins GJ, Kinzler KW, Vogelstein B, Hruban RH, Maitra A, Papadopoulos N, Meeker AK. Altered telomeres in tumors with ATRX and DAXX mutations. Science 2011; 333:425. [PMID: 21719641 PMCID: PMC3174141 DOI: 10.1126/science.1207313] [Citation(s) in RCA: 789] [Impact Index Per Article: 60.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The proteins encoded by ATRX and DAXX participate in chromatin remodeling at telomeres and other genomic sites. Because inactivating mutations of these genes are common in human pancreatic neuroendocrine tumors (PanNETs), we examined the telomere status of these tumors. We found that 61% of PanNETs displayed abnormal telomeres that are characteristic of a telomerase-independent telomere maintenance mechanism termed ALT (alternative lengthening of telomeres). All of the PanNETs exhibiting these abnormal telomeres had ATRX or DAXX mutations or loss of nuclear ATRX or DAXX protein. ATRX mutations also correlate with abnormal telomeres in tumors of the central nervous system. These data suggest that an alternative telomere maintenance function may operate in human tumors with alterations in the ATRX or DAXX genes.
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Affiliation(s)
- Christopher M. Heaphy
- Department of Pathology, The Sol Goldman Pancreatic Cancer Research Center, the Johns Hopkins Medical Institutions, Baltimore, Maryland, USA
| | - Roeland F. de Wilde
- Department of Pathology, The Sol Goldman Pancreatic Cancer Research Center, the Johns Hopkins Medical Institutions, Baltimore, Maryland, USA
| | - Yuchen Jiao
- Ludwig Center for Cancer Genetics and Howard Hughes Medical Institutions, Johns Hopkins Kimmel Cancer Center, Baltimore, Maryland, USA
| | - Alison P. Klein
- Department of Pathology, The Sol Goldman Pancreatic Cancer Research Center, the Johns Hopkins Medical Institutions, Baltimore, Maryland, USA
- Department of Oncology, the Johns Hopkins Medical Institutions, Baltimore, Maryland, USA
- Department of Epidemiology, Bloomberg School of Public Health, The Johns Hopkins University, Baltimore, Maryland, USA
| | - Barish H. Edil
- Department of Oncology, the Johns Hopkins Medical Institutions, Baltimore, Maryland, USA
| | - Chanjuan Shi
- Department of Pathology, Vanderbilt University, Nashville, Tennessee, USA
| | - Chetan Bettegowda
- Ludwig Center for Cancer Genetics and Howard Hughes Medical Institutions, Johns Hopkins Kimmel Cancer Center, Baltimore, Maryland, USA
- Department of Neurosurgery, the Johns Hopkins Medical Institutions, Baltimore, Maryland, USA
| | - Fausto J. Rodriguez
- Department of Pathology, The Sol Goldman Pancreatic Cancer Research Center, the Johns Hopkins Medical Institutions, Baltimore, Maryland, USA
| | - Charles G. Eberhart
- Department of Pathology, The Sol Goldman Pancreatic Cancer Research Center, the Johns Hopkins Medical Institutions, Baltimore, Maryland, USA
| | - Sachidanand Hebbar
- Department of Pathology, The Sol Goldman Pancreatic Cancer Research Center, the Johns Hopkins Medical Institutions, Baltimore, Maryland, USA
| | - G. Johan Offerhaus
- Department of Pathology, University Medical Center Utrecht, the Netherlands
| | - Roger McLendon
- The Preston Rober Tisch Brain Tumor Center at Duke, The Pediatric Brain Tumor Foundation Institute and the Department of Pathology, Duke University Medical Center, Durham, North Carolina, USA
| | - B. Ahmed Rasheed
- The Preston Rober Tisch Brain Tumor Center at Duke, The Pediatric Brain Tumor Foundation Institute and the Department of Pathology, Duke University Medical Center, Durham, North Carolina, USA
| | - Yiping He
- The Preston Rober Tisch Brain Tumor Center at Duke, The Pediatric Brain Tumor Foundation Institute and the Department of Pathology, Duke University Medical Center, Durham, North Carolina, USA
| | - Hai Yan
- The Preston Rober Tisch Brain Tumor Center at Duke, The Pediatric Brain Tumor Foundation Institute and the Department of Pathology, Duke University Medical Center, Durham, North Carolina, USA
| | - Darell D. Bigner
- The Preston Rober Tisch Brain Tumor Center at Duke, The Pediatric Brain Tumor Foundation Institute and the Department of Pathology, Duke University Medical Center, Durham, North Carolina, USA
| | | | | | - Gregory J. Riggins
- Department of Neurosurgery, the Johns Hopkins Medical Institutions, Baltimore, Maryland, USA
| | - Kenneth W. Kinzler
- Ludwig Center for Cancer Genetics and Howard Hughes Medical Institutions, Johns Hopkins Kimmel Cancer Center, Baltimore, Maryland, USA
| | - Bert Vogelstein
- Ludwig Center for Cancer Genetics and Howard Hughes Medical Institutions, Johns Hopkins Kimmel Cancer Center, Baltimore, Maryland, USA
| | - Ralph H. Hruban
- Department of Pathology, The Sol Goldman Pancreatic Cancer Research Center, the Johns Hopkins Medical Institutions, Baltimore, Maryland, USA
- Department of Oncology, the Johns Hopkins Medical Institutions, Baltimore, Maryland, USA
| | - Anirban Maitra
- Department of Pathology, The Sol Goldman Pancreatic Cancer Research Center, the Johns Hopkins Medical Institutions, Baltimore, Maryland, USA
- Department of Oncology, the Johns Hopkins Medical Institutions, Baltimore, Maryland, USA
| | - Nickolas Papadopoulos
- Ludwig Center for Cancer Genetics and Howard Hughes Medical Institutions, Johns Hopkins Kimmel Cancer Center, Baltimore, Maryland, USA
| | - Alan K. Meeker
- Department of Pathology, The Sol Goldman Pancreatic Cancer Research Center, the Johns Hopkins Medical Institutions, Baltimore, Maryland, USA
- Department of Oncology, the Johns Hopkins Medical Institutions, Baltimore, Maryland, USA
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Henson JD, Reddel RR. Assaying and investigating Alternative Lengthening of Telomeres activity in human cells and cancers. FEBS Lett 2010; 584:3800-11. [PMID: 20542034 DOI: 10.1016/j.febslet.2010.06.009] [Citation(s) in RCA: 180] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2010] [Accepted: 06/08/2010] [Indexed: 12/14/2022]
Abstract
Alternative Lengthening of Telomeres (ALT) activity can be deduced from the presence of telomere length maintenance in the absence of telomerase activity. More convenient assays for ALT utilize phenotypic markers of ALT activity, but only a few of these assays are potentially definitive. Here we assess each of the current ALT assays and their implications for understanding the ALT mechanism. We also review the clinical situations where availability of an ALT activity assay would be advantageous. The prevalence of ALT ranges from 25% to 60% in sarcomas and 5% to 15% in carcinomas. Patients with many of these types of ALT[+] tumors have a poor prognosis.
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Affiliation(s)
- Jeremy D Henson
- Children's Medical Research Institute, Sydney, NSW, Australia
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19
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Telomere and telomerase as targets for cancer therapy. Appl Biochem Biotechnol 2009; 160:1460-72. [PMID: 19412578 DOI: 10.1007/s12010-009-8633-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2009] [Accepted: 03/31/2009] [Indexed: 02/08/2023]
Abstract
Telomere maintenance and telomerase reactivation is essential for the transformation of most human cancer cells. Telomere shortening to the threshold length, mutations of the telomere-associated proteins, and/or telomerase RNA lead to telomeric dysfunction and therefore genomic instability. Telomerase up-regulation in 85% of human cancer cells has become a hallmark of cancers, hence a promising target for anticancer therapy. In this review, we discuss the mechanism of cancer due to telomere dysfunction and the resulting biological effects, the control of telomerase activity, and the new developments in cancer therapies targeting telomere and telomerase.
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20
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Matsuo T, Shay JW, Wright WE, Hiyama E, Shimose S, Kubo T, Sugita T, Yasunaga Y, Ochi M. Telomere-maintenance mechanisms in soft-tissue malignant fibrous histiocytomas. J Bone Joint Surg Am 2009; 91:928-37. [PMID: 19339578 DOI: 10.2106/jbjs.g.01390] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
BACKGROUND Sarcomas are distinct from carcinomas in that a substantial portion of them use the alternative lengthening of telomeres (ALT) mechanism to maintain their telomeres. The present study clarifies the prevalence of the ALT mechanism and examines the prognostic importance of telomere factors in soft-tissue malignant fibrous histiocytomas. METHODS We investigated a series of forty-three soft-tissue malignant fibrous histiocytoma samples from forty-three patients with regard to telomere length, telomerase activity, and human telomerase reverse transcriptase (hTERT) mRNA expression. Tumor samples were obtained from surgical specimens and were stored at -80 degrees C until use. Univariate analysis of the tumor samples from patients for whom data were available on age, sex, histological grade, tumor size, surgical margin, recurrence, and telomere factors was performed with use of the log-rank test. Multivariate analysis with only significant variables was then performed. RESULTS Telomerase activity was detectable in 79.1% of the tumor samples, hTERT expression was demonstrated in 90.7% of the tumor samples, and evidence of engagement of the ALT mechanism of telomere length maintenance was observed in 32.6% of the tumor samples. Among the variables tested, ALT-positive status emerged as the only independent prognostic factor for death of the patient (hazard ratio, 0.275; 95% confidence interval, 0.104 to 0.724; p=0.0089). There were no significant differences in survival rates between patients with ALT-positive, telomerase-positive tumors and those with ALT-positive, telomerase-negative tumors (p=0.301) or between patients with ALT-positive tumors that showed above-average telomerase activity and those with ALT-positive tumors that showed below-average telomerase activity (p=0.900). Therefore, telomerase activity does not affect the prognosis in patients with ALT-positive malignant fibrous histiocytoma. High telomerase expression is associated with a poor prognosis in patients with ALT-negative malignant fibrous histiocytoma (p=0.0027). CONCLUSIONS More detailed analysis will be needed to identify the most valuable prognostic factor in patients with malignant fibrous histiocytoma, and a more thorough understanding of telomere biology may give an indication of telomere-targeting therapy in the future.
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Affiliation(s)
- Toshihiro Matsuo
- Department of Artificial Joints and Biomaterials, Graduate School of Biomedical Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8551, Japan.
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Proctor A, Brownhill SC, Burchill SA. The promise of telomere length, telomerase activity and its regulation in the translocation-dependent cancer ESFT; clinical challenges and utility. Biochim Biophys Acta Mol Basis Dis 2009; 1792:260-74. [PMID: 19264125 DOI: 10.1016/j.bbadis.2009.02.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2009] [Revised: 02/19/2009] [Accepted: 02/20/2009] [Indexed: 01/12/2023]
Abstract
The Ewing's sarcoma family of tumours (ESFT) are diagnosed by EWS-ETS gene translocations. The resulting fusion proteins play a role in both the initiation and maintenance of these solid aggressive malignant tumours, suppressing cellular senescence and increasing cell proliferation and survival. EWS-ETS fusion proteins have altered transcriptional activity, inducing expression of a number of different target genes including telomerase. Up-regulation of hTERT is most likely responsible for the high levels of telomerase activity in primary ESFT, although telomerase activity and expression of hTERT are not predictive of outcome. However levels of telomerase activity in peripheral blood may be useful to monitor response to some therapeutics. Despite high levels of telomerase activity, telomeres in ESFT are frequently shorter than those of matched normal cells. Uncertainty about the role that telomerase and regulators of its activity play in the maintenance of telomere length in normal and cancer cells, and lack of studies examining the relationship between telomerase activity, regulators of its activity and their clinical significance in patient samples have limited their introduction into clinical practice. Studies in clinical samples using standardised assays are critical to establish how telomerase and regulators of its activity might best be exploited for patient benefit.
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Affiliation(s)
- Andrew Proctor
- Cancer Research UK Clinical Centre, Leeds Institute of Molecular Medicine, St James's University Hospital, Beckett Street, Leeds LS9 7TF, UK
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22
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Ohali A, Avigad S, Naumov I, Goshen Y, Ash S, Yaniv I. Different telomere maintenance mechanisms in alveolar and embryonal rhabdomyosarcoma. Genes Chromosomes Cancer 2008; 47:965-70. [DOI: 10.1002/gcc.20600] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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23
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Mantripragada KK, Caley M, Stephens P, Jones CJ, Kluwe L, Guha A, Mautner V, Upadhyaya M. Telomerase activity is a biomarker for high grade malignant peripheral nerve sheath tumors in neurofibromatosis type 1 individuals. Genes Chromosomes Cancer 2008; 47:238-46. [PMID: 18069666 DOI: 10.1002/gcc.20525] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Telomerase activity (TA) and the expression of its enzymatic subunits, which have been demonstrated in many tumors, remain poorly investigated in tumors associated with neurofibromatosis type 1 (NF1). In this study, we analysed the association of TA and the expression of telomerase RNA (TR) and telomerase reverse transcriptase (TERT) in 23 malignant peripheral nerve sheath tumors (MPNST) (17 high grade and 6 low grade tumors), 11 plexiform neurofibromas (PNF) and 6 dermal neurofibromas (DNF). TA was studied using telomerase repeat amplification protocol (TRAP) assay and expression of TR and TERT was investigated using reverse transcription PCR (RT-PCR) and real-time PCR. TA was detected in 14 out of 17 (82%) high grade MPNST, whereas all 6 low grade MPNST and 17 benign tumors were telomerase negative. The TERT transcripts were detected in all high grade MPNST, 50% of the low grade MPNST, and 4 benign tumors. However, the expression level of the TERT strikingly correlated with TA and high grade MPNST. Thus, while TERT expression was similar in both low grade MPNST and PNF (P = 0.115), it was significantly higher in high grade MPNST when compared to either low grade MPNST (P = 0.042), PNF (P = 0.001) or DNF tumors (P = 0.010). These findings indicate that TA and expression level of TERT are potential markers for high grade malignancy in NF1 patients.
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Avigad S, Naumov I, Ohali A, Jeison M, Berco GH, Mardoukh J, Stark B, Ash S, Cohen IJ, Meller I, Kollender Y, Issakov J, Yaniv I. Short telomeres: a novel potential predictor of relapse in Ewing sarcoma. Clin Cancer Res 2007; 13:5777-83. [PMID: 17908968 DOI: 10.1158/1078-0432.ccr-07-0308] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE Despite advances in therapy, >50% of patients with Ewing sarcoma will relapse. The current prognostic factors are not optimal for risk prediction. Studies have shown that telomere length could predict outcome in different malignancies. Our aim was to evaluate whether telomere length could be a better prognostic factor in Ewing sarcoma and correlate the results with clinical variables, outcome, and chromosomal instability. EXPERIMENTAL DESIGN Telomere length was determined in the primary tumor and peripheral blood of 32 patients with Ewing sarcoma. Chromosomal instability was evaluated by combining classical cytogenetics, comparative genomic hybridization and random aneuploidy. Telomere length was correlated to clinical variables, chromosomal instability, and outcome. RESULTS In 75% of the tumors, changes in telomere length, when compared with the corresponding peripheral blood lymphocytes, were noted. The majority of changes consisted of a reduction in telomere length. Patients harboring shorter telomeres had a significantly adverse outcome (P = 0.015). Chromosomal instability was identified in 65% of tumors, significantly correlating with short telomeres (P = 0.0094). Using multivariate analysis, telomere length remained the only significant prognostic variable (P = 0.034). Patients with short telomeres had a 5.3-fold risk of relapse as compared to those with unchanged or longer telomeres. CONCLUSION We have shown that tumors with telomere length reduction result in genomic instability. In addition, telomere length reduction was the only significant predictor of outcome. We suggest that reduction of telomere length in tumor cells at diagnosis could serve as a prognostic marker in Ewing sarcoma.
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Affiliation(s)
- Smadar Avigad
- Molecular Oncology, Felsenstein Medical Research Center, Petach Tikva, Israel.
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Abstract
PURPOSE OF REVIEW To examine the activation of telomere maintenance in a variety of sarcoma subtypes, and to review the consequences of telomere maintenance with respect to genome stability and tumor progression. RECENT FINDINGS A hallmark of tumor cells is replicative immortality, which can be achieved, in part, by the activation of a telomere maintenance mechanism. A significant proportion of tumors show activation of telomerase, a specialized enzyme that adds telomeric repeats to pre-existing telomeres. Recent work has demonstrated, however, that a telomerase-independent mechanism called ALT (alternative lengthening of telomeres) is activated as frequently as telomerase in a variety of tumor types, particularly those of mesenchymal origin. Accordingly, panels of mesenchymal tumors have been interrogated for telomere maintenance mechanism, as well as characteristics such as tumor grade and patient survival. SUMMARY These studies indicate a strong positive correlation between the activation of a telomere maintenance mechanism and tumor progression in sarcomas. In addition, the activation of either ALT or telomerase is correlated with poorer patient prognosis as compared with a lack of telomere maintenance. Ongoing studies aimed at elucidating the roles of ALT and telomerase in tumorigenesis should ultimately allow for the development of strategies to improve treatment of these malignancies.
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Affiliation(s)
- Jay E Johnson
- Department of Laboratory Oncology Research, Curtis and Elizabeth Anderson Cancer Institute, Memorial Health University Medical Center, Savannah, Georgia 31404, USA
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Abstract
One of the hallmarks of cancer is limitless proliferative capacity, which is tightly associated with the ability to maintain telomeres. Over the last decade, the telomere biology of pediatric cancers has begun to be elucidated. Most pediatric leukemias and embryonal solid tumors activate the enzyme telomerase, a specialized reverse transcriptase that adds nucleotide repeats to telomeres. In general, high levels of tumor telomerase expression are associated with unfavorable outcome, although results vary according to tumor type. Some pediatric tumors, including osteosarcoma and glioblastoma multiforme, lack telomerase activity and maintain telomeres via a recombination-based mechanism called ALT (alternative lengthening of telomeres). Telomerase is a highly attractive therapeutic target for pediatric cancer because the enzyme plays a key role in conferring cellular immortality, is present in most tumors, and is relatively specific for cancer cells. Telomerase inhibitors have been evaluated in preclinical models of adult cancers, but few studies have been conducted on pediatric cancers. Further research is required to define how telomere biology can be used to clinical advantage in malignancies of childhood.
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Affiliation(s)
- Uri Tabori
- Department of Hematology/Oncology, Hospital for Sick Children, Toronto, Canada
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Abstract
The structure and integrity of telomeres are essential for genome stability. Telomere dysregulation can lead to cell death, cell senescence, or abnormal cell proliferation. The maintenance of telomere repeats in most eukaryotic organisms requires telomerase, which consists of a reverse transcriptase (RT) and an RNA template that dictates the synthesis of the G-rich strand of telomere terminal repeats. Structurally, telomerase reverse transcriptase (TERT) contains unique and variable N- and C-terminal extensions that flank a central RT-like domain. The enzymology of telomerase includes features that are both similar to and distinct from those characteristic of other RTs. Two distinguishing features of TERT are its stable association with the telomerase RNA and its ability to repetitively reverse transcribe the template segment of RNA. Here we discuss TERT structure and function; its regulation by RNA-DNA, TERT-DNA, TERT-RNA, TERT-TERT interactions, and TERT-associated proteins; and the relationship between telomerase enzymology and telomere maintenance.
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Affiliation(s)
- Chantal Autexier
- Bloomfield Center for Research in Aging, Lady Davis Institute for Medical Research, Sir Mortimer B. Davis Jewish General Hospital, Quebec, Canada.
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Edqvist A, Rebetz J, Järås M, Rydelius A, Skagerberg G, Salford LG, Widegren B, Fan X. Detection of cell cycle- and differentiation stage-dependent human telomerase reverse transcriptase expression in single living cancer cells. Mol Ther 2006; 14:139-48. [PMID: 16584924 DOI: 10.1016/j.ymthe.2005.12.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2005] [Revised: 12/15/2005] [Accepted: 12/27/2005] [Indexed: 11/18/2022] Open
Abstract
Elevated telomerase activity is an important molecular signature of cancer cells and primitive cells in regenerative tissues. However, isolation of single living cells with endogenous telomerase activity has not yet been possible. Here, we developed adenovirus serotype 35 tropism-based vectors encoding destabilized enhanced green fluorescence protein with a half-life of 2 h (d2EGFP) driven by the human telomerase reverse transcriptase (hTERT) promoter. As assessed in telomerase-positive or -negative cell lines, the d2EGFP expression positively correlated with hTERT transcript content and telomerase activity. In retinoic acid-induced differentiating HL-60 cells, the d2EGFP expression is diminished in the same manner as the hTERT expression. Individual cells from HeLa and HL-60 cell lines exhibited heterogeneous d2EGFP expression, which was cell cycle dependent, as the sorted d2EGFP+ HL-60 cells contained twice as many cells in S/G2/M phase of the cell cycle compared with the d2EGFP- HL-60 cells. However, both cell populations exhibited the same proliferation and regeneration capacities. Heterogeneous d2EGFP expression was also detected in xenograft glioblastoma multiforme cells with tumor formation capacity. Thus, d2EGFP expression reported cell cycle- and differentiation stage-dependent hTERT expression. Our study facilitates isolation and characterization of single living cells with telomerase activity.
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Affiliation(s)
- Anna Edqvist
- Section of Immunology, Lund Strategic Research Center for Stem Cell Biology and Cell Therapy, Lund University, Lund, Sweden
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Swiggers SJJ, Kuijpers MA, de Cort MJM, Beverloo HB, Zijlmans JMJM. Critically short telomeres in acute myeloid leukemia with loss or gain of parts of chromosomes. Genes Chromosomes Cancer 2006; 45:247-56. [PMID: 16281260 DOI: 10.1002/gcc.20286] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Telomeres, nucleoprotein complexes at chromosome ends, protect chromosomes against end-to-end fusion. Previous in vitro studies in human fibroblast models indicated that telomere dysfunction results in chromosome instability. Loss of telomere function can result either from critical shortening of telomeric DNA or from loss of distinct telomere-capping proteins. It is less clear whether telomere dysfunction has an important role in human cancer development in vivo. Acute myeloid leukemia (AML) is a good model to study mechanisms that generate chromosome instability in human cancer development because distinct groups of AML are characterized either by aberrations that theoretically could result from telomere dysfunction (terminal deletions, gains/losses of chromosome parts, nonreciprocal translocations), or aberrations that are unlikely to result from telomere dysfunction (e.g., reciprocal translocations or inversions). Here we demonstrate that AML with multiple chromosome aberrations that theoretically could result from telomere dysfunction is invariably characterized by critically short telomeres. Short telomeres in this group are not associated with low telomerase activity or decreased expression of essential telomeric capping proteins TRF2 and POT1. In contrast, telomerase activity levels are significantly higher in AML with short telomeres. Notably, short telomeres in the presence of high telomerase may relate to significantly higher expression of TRF1, a negative regulator of telomere length. Our observations suggest that, consistent with previous in vitro fibroblast models, age-related critical telomere shortening may have a role in generating chromosome instability in human AML development.
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Henson JD, Hannay JA, McCarthy SW, Royds JA, Yeager TR, Robinson RA, Wharton SB, Jellinek DA, Arbuckle SM, Yoo J, Robinson BG, Learoyd DL, Stalley PD, Bonar SF, Yu D, Pollock RE, Reddel RR. A Robust Assay for Alternative Lengthening of Telomeres in Tumors Shows the Significance of Alternative Lengthening of Telomeres in Sarcomas and Astrocytomas. Clin Cancer Res 2005. [DOI: 10.1158/1078-0432.217.11.1] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Abstract
Purpose and Experimental Design: Telomeres of tumor cells may be maintained by telomerase or by alternative lengthening of telomeres (ALT). The standard ALT assay requires Southern analysis of high molecular weight genomic DNA. We aimed to establish and validate an ALT assay suitable for archived paraffin-embedded tumors and to use it to examine the prevalence and clinical significance of ALT in various types of tumors that are often telomerase negative.
Results: To assay for ALT, we detected ALT-associated promyelocytic leukemia (PML) bodies (APBs) by combined PML immunofluorescence and telomere fluorescence in situ hybridization. APBs are PML nuclear domains containing telomeric DNA and are a known hallmark of ALT in cell lines. The APB assay concurred with the standard ALT assay in 62 of 62 tumors and showed that 35% of 101 soft tissue sarcomas (STS), 47% of 58 osteosarcomas (especially younger patients), 34% of 50 astrocytomas, and 0% of 17 papillary thyroid carcinomas were ALT positive (ALT+). The prevalence of ALT varied greatly among different STS subtypes: malignant fibrous histiocytomas, 77%; leiomyosarcomas, 62%; liposarcomas, 33%; synovial sarcomas, 9%; and rhabdomyosarcomas, 6%. ALT correlated with survival in glioblastoma multiforme and occurred more often in lower-grade astrocytomas, but ALT+ and ALT− sarcomas were equally aggressive in terms of grade and clinical outcome.
Conclusion: The APB assay for ALT is suitable for paraffin-embedded tumors. It showed that a substantial proportion of STS, osteosarcomas, and astrocytomas, but not papillary thyroid carcinomas use ALT. APB positivity correlated strongly with survival of patients with astrocytomas.
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Affiliation(s)
| | | | | | - Janice A. Royds
- 7University of Otago, Dunedin, New Zealand
- 8Royal Hallamshire Hospital, Sheffield, United Kingdom
| | | | | | | | | | | | - Jinyoung Yoo
- 10Department of Pathology, St Vincent's Hospital, Catholic University, Suwon, Kyungkido, South Korea
| | | | | | | | - S. Fiona Bonar
- 5Douglass Hanly Moir Pathology, Sydney, New South Wales, Australia
| | - Dihua Yu
- 6MD Anderson Cancer Center, Houston, Texas
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Sandberg AA. Updates on the cytogenetics and molecular genetics of bone and soft tissue tumors: liposarcoma. ACTA ACUST UNITED AC 2004; 155:1-24. [PMID: 15527898 DOI: 10.1016/j.cancergencyto.2004.08.005] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2004] [Revised: 07/09/2004] [Accepted: 07/12/2004] [Indexed: 11/21/2022]
Affiliation(s)
- Avery A Sandberg
- Department of DNA Diagnostics, St. Joseph's Hospital and Medical Center, 350 West Thomas Road, Phoenix, AZ 85013, USA.
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Ulaner GA, Hoffman AR, Otero J, Huang HY, Zhao Z, Mazumdar M, Gorlick R, Meyers P, Healey JH, Ladanyi M. Divergent patterns of telomere maintenance mechanisms among human sarcomas: sharply contrasting prevalence of the alternative lengthening of telomeres mechanism in Ewing's sarcomas and osteosarcomas. Genes Chromosomes Cancer 2004; 41:155-62. [PMID: 15287028 DOI: 10.1002/gcc.20074] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Two types of telomere maintenance mechanisms (TMMs) have been described in human tumors: telomerase activation and alternative lengthening of telomeres (ALT). Although the vast majority of epithelial tumors rely on telomerase activation, many mesenchymal tumors rely on ALT for telomere maintenance, but within this tumor group, the TMMs used by translocation-associated sarcomas have not been systematically studied. We studied telomere lengths and telomerase expression and activity in 30 uncultured tumor samples and in 10 cell lines of Ewing's sarcoma, a prototypical translocation-associated sarcoma, and compared the data to an identical analysis of 60 osteosarcomas, the most common type of sarcoma lacking a specific translocation. Telomerase activity was demonstrated in 21 Ewing's sarcoma tumor samples (70%) and in 9 of 10 Ewing's sarcoma cell lines. Evidence of ALT, indicated by the presence of long and heterogeneous telomeres, was observed only in the cell line without telomerase activity and in none of the 30 Ewing's sarcoma tumor samples. The 9 Ewing's sarcoma patients whose tumors lacked detectable telomerase activity did not differ significantly from the remaining patients in age, stage, EWSR1-FLI1 fusion type, prevalence of TP53 point mutations, or overall survival. The low prevalence of ALT in Ewing's sarcoma contrasted sharply with our data on TMMs in 60 osteosarcomas, which showed ALT in 38 of 60 cases (P<0.0001). The present study, together with emerging published data on other sarcoma types, suggests that a predominance of telomerase activation in the absence of ALT may characterize sarcomas with specific chromosomal translocations (such as Ewing's sarcoma), whereas a high prevalence of ALT appears typical of sarcomas with nonspecific complex karyotypes (such as osteosarcoma).
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Affiliation(s)
- Gary A Ulaner
- Medical Service, VA Palo Alto Health Care System, and Department of Medicine, Stanford University, Palo Alto, California 94304, USA.
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Swiggers SJJ, Nibbeling HAJ, Zeilemaker A, Kuijpers MA, Mattern KA, Zijlmans JMJM. Telomerase activity level, but not hTERT mRNA and hTR level, regulates telomere length in telomerase-reconstituted primary fibroblasts. Exp Cell Res 2004; 297:434-43. [PMID: 15212946 DOI: 10.1016/j.yexcr.2004.03.028] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2003] [Revised: 02/19/2004] [Indexed: 12/31/2022]
Abstract
The critical factors in the regulation of telomere length are not yet clearly defined. Telomerase is a key player in telomere elongation, although previous studies have shown that telomeres are differentially elongated after telomerase reconstitution. Moreover, a clear relation between the level of telomerase activity and telomere length was not observed. To investigate which factors are critical in telomere length regulation, we generated 24 telomerase-reconstituted primary human fibroblast clones. In these clones, in vitro telomerase activity level is clearly related to telomere length. High levels of telomerase activity are associated with longer telomeres and better telomere maintenance over time. The correlation coefficient, however, indicates that the level of telomerase activity is not the only factor in the regulation of telomere length. Clearly, factors that are not measured in an in vitro telomerase activity assay are involved in telomere length regulation in vivo. To investigate which telomerase components are critical in regulating telomerase activity levels, we studied expression levels of hTERT mRNA and hTR. Expression is highly variable between individual clones, but not related to the level of telomerase activity or telomere length. Our results indicate that expression levels of hTERT mRNA and hTR do not regulate the activity level of the telomerase complex, suggesting posttranscriptional modification of hTERT or the presence of additional proteins that modulate telomerase enzyme activity.
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Affiliation(s)
- Susan J J Swiggers
- Department of Hematology, Erasmus University Medical Center, Rotterdam, The Netherlands
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Montgomery E, Argani P, Hicks JL, DeMarzo AM, Meeker AK. Telomere lengths of translocation-associated and nontranslocation-associated sarcomas differ dramatically. THE AMERICAN JOURNAL OF PATHOLOGY 2004; 164:1523-9. [PMID: 15111298 PMCID: PMC1615673 DOI: 10.1016/s0002-9440(10)63710-8] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Sarcomas can be divided into those with specific translocations displaying monotonous cytomorphology, and those with complex karyotypes and marked cellular pleomorphism. Telomeres contain terminal DNA sequence repeats that maintain chromosomal stability. Telomeres shorten with cell division and may become dysfunctional leading to chromosomal instability. Using a fluorescence in situ hybridization/immunofluorescence method to assess telomere lengths in archival tissues we analyzed these two types of sarcomas using paraffin-embedded primary tumor specimens. Tissues from nine sarcomas with characteristic translocations (two synovial sarcomas, two alveolar rhabdomyosarcomas, two desmoplastic round cell tumors, and one each of infantile fibrosarcoma, myxoid liposarcoma, cellular congenital mesoblastic nephroma) and nine without (four malignant fibrous histiocytomas, two leiomyosarcomas, one pleomorphic rhabdomyosarcoma, one dedifferentiated chondrosarcoma, and one malignant peripheral nerve sheath tumor) were analyzed. In all (nine of nine) cases with specific translocations, which generally have few karyotypic abnormalities, telomere lengths were similar to or reduced compared to surrounding nonneoplastic tissues. In contrast, telomeres in cases lacking specific translocations, which generally contain complex karyotypes, were often found to be dramatically lengthened and heterogeneous. In addition to markedly elongated telomeres, seven of nine (78%) complex cases exhibited large brightly stained regions corresponding to a specific type of promyelocytic leukemia nuclear body found in immortalized cells that maintain telomeres in a telomerase-independent manner [alternative lengthening of telomeres (ALT) pathway]. This phenotype is unlike that of epithelial neoplasms that typically display complex karyotypes with abnormally short telomeres maintained by the enzyme telomerase. The discovery of heterogeneous telomere lengths and evidence of the ALT pathway in the majority of sarcomas with complex karyotypes supports the existence of a telomere maintenance pathway incapable of full karyotypic stabilization in pleomorphic sarcomas. These findings provide additional molecular-genetic evidence supporting the dichotomous grouping of sarcomas into those with characteristic signature translocations without extensive additional karyotypic abnormalities, and those without such signature translocations that typically display very complex karyotypes, and point to telomere dysfunction as a plausible contributor to the chromosomal aberrations found in complex sarcomas.
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Affiliation(s)
- Elizabeth Montgomery
- Department of Pathology, Johns Hopkins Medical Institutions, Baltimore, Maryland 21231-1000, USA
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Grimm J, Perez JM, Josephson L, Weissleder R. Novel nanosensors for rapid analysis of telomerase activity. Cancer Res 2004; 64:639-43. [PMID: 14744779 DOI: 10.1158/0008-5472.can-03-2798] [Citation(s) in RCA: 136] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Elevated telomerase levels are found in many malignancies, offering an attractive target for therapeutic intervention and diagnostic or prognostic purposes. Here we describe the use of a novel nanosensor developed for rapid screens of telomerase activity in biological samples. The technique utilizes magnetic nanoparticles that, on annealing with telomerase synthesized TTAGGG repeats, switch their magnet state, a phenomenon readily detectable by magnetic readers. We tested the efficacy of different telomerase inhibitors in crude human and murine samples and show that phosphorylation of telomerase regulates its activity. High-throughput adaptation of the technique by magnetic resonance imaging allowed processing of hundreds of samples within tens of minutes at ultrahigh sensitivities. Together, these studies establish and validate a novel and powerful tool for rapidly sensing telomerase activity and provide the rationale for developing analogous magnetic nanoparticles for in vivo sensing.
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Affiliation(s)
- Jan Grimm
- Center for Molecular Imaging Research, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
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36
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Guilleret I, Benhattar J. Demethylation of the human telomerase catalytic subunit (hTERT) gene promoter reduced hTERT expression and telomerase activity and shortened telomeres. Exp Cell Res 2003; 289:326-34. [PMID: 14499633 DOI: 10.1016/s0014-4827(03)00281-7] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Telomerase is the ribonucleoproteic complex involved in maintaining telomere size. It is expressed in germ and stem cells but not in normal somatic cells. In most tumors, telomerase is reactivated. In humans, telomerase activity is tightly regulated by expression of the hTERT gene. In a previous study, we found a direct correlation between methylation of the hTERT promoter and hTERT gene expression. In order to demonstrate this correlation, demethylation experiments were performed with the demethylating agent 5aza-2'-deoxycytidine (5azadC). Three telomerase-positive tumor cell lines (Lan-1, HeLa, and Co115), presenting a hypermethylated hTERT promoter, were treated with different doses and types of treatment for a long period. Analysis of methylation revealed a final hTERT promoter demethylation up to 95%. Quantification of hTERT mRNA showed that transcription was strongly repressed during drug exposure. In contrast, expression of c-Myc, an activator of hTERT promoter, was barely down-regulated or increased by the treatment. Using a TRAP assay, telomerase activity was semiquantified in all experiments. It strongly decreased or was suppressed after two to four passages. Finally, telomere length was measured by Southern blot. Their averages were not modified, but ranges concentrated around the mean. Thus, it is likely that hTERT promoter hypermethylation would be necessary for its expression.
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MESH Headings
- Antimetabolites, Antineoplastic/pharmacology
- Azacitidine/analogs & derivatives
- Azacitidine/pharmacology
- Cell Division/drug effects
- Cell Division/genetics
- Cellular Senescence/drug effects
- Cellular Senescence/genetics
- DNA Methylation/drug effects
- DNA-Binding Proteins
- Decitabine
- Down-Regulation/drug effects
- Down-Regulation/genetics
- Gene Expression Regulation, Neoplastic/drug effects
- Gene Expression Regulation, Neoplastic/genetics
- Humans
- Neoplasms/enzymology
- Neoplasms/genetics
- Promoter Regions, Genetic/drug effects
- Promoter Regions, Genetic/genetics
- Proto-Oncogene Proteins c-myc/drug effects
- Proto-Oncogene Proteins c-myc/genetics
- Proto-Oncogene Proteins c-myc/metabolism
- RNA, Messenger/drug effects
- RNA, Messenger/metabolism
- Telomerase/drug effects
- Telomerase/genetics
- Telomerase/metabolism
- Telomere/drug effects
- Telomere/genetics
- Telomere/metabolism
- Transcription, Genetic/drug effects
- Transcription, Genetic/genetics
- Tumor Cells, Cultured
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Affiliation(s)
- Isabelle Guilleret
- Institut de Pathologie, Centre Hospitalier Universitaire Vaudois, CH-1011 Lausanne, Switzerland
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Kleideiter E, Schwab M, Friedrich U, Koscielniak E, Schafer BW, Klotz U. Telomerase activity in cell lines of pediatric soft tissue sarcomas. Pediatr Res 2003; 54:718-23. [PMID: 12904596 DOI: 10.1203/01.pdr.0000086901.29111.2a] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Telomeres and their maintenance by telomerase have been implicated to play an important role in carcinogenesis. As almost all malignant tumors express telomerase (in contrast to normal somatic cells), assessment of its activity has been proposed as a diagnostic and prognostic tool. To test the prognostic value of telomerase in pediatric soft tissue sarcoma (STS), we analyzed telomere length (by telomere restriction fragment analysis), telomerase activity (by modified telomerase repeat amplification protocol assay), and expression of human telomerase reverse transcriptase (hTERT) mRNA (by TaqMan technique) in cell lines of different types of STS from 12 children and adolescents. Telomere length (3.7-9.0 kb) showed a very heterogeneous pattern, independent of subtype of STS or the age of the patients, and it was not associated with expression of hTERT mRNA. In contrast, there was a trend of an association between hTERT and telomerase activity. The three tested cell lines of embryonal rhabdomyosarcomas demonstrated no or low (n = 2) telomerase activity, which was confirmed in two cases by a very low expression of hTERT mRNA. Thus, we suggest that the significant difference (p < 0.01) in the less aggressive clinical behavior of embryonal rhabdomyosarcomas in comparison to other subtypes may be due to differences in telomerase expression. Taken together, our cell line experiments imply that telomerase activity might be a biologic marker for stratification between STS with different clinical prognosis.
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Affiliation(s)
- Elke Kleideiter
- Dr Margarete Fischer-Bosch Institute of Clinical Pharmacology, Stuttgart, Germany
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