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Loe TK, Lazzerini Denchi E, Tricola GM, Azeroglu B. ALTercations at telomeres: stress, recombination and extrachromosomal affairs. Biochem Soc Trans 2023; 51:1935-1946. [PMID: 37767563 DOI: 10.1042/bst20230265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 09/21/2023] [Accepted: 09/22/2023] [Indexed: 09/29/2023]
Abstract
Approximately 15% of human cancers depend on the alternative lengthening of telomeres (ALT) pathway to maintain telomeres and proliferate. Telomeres that are elongated using ALT display unique features raising the exciting prospect of tailored cancer therapies. ALT-mediated telomere elongation shares several features with recombination-based DNA repair. Strikingly, cells that use the ALT pathway display abnormal levels of replication stress at telomeres and accumulate abundant extrachromosomal telomeric DNA. In this review, we examine recent findings that shed light on the ALT mechanisms and the strategies currently available to suppress this telomere elongation mechanism.
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Affiliation(s)
- Taylor K Loe
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, U.S.A
| | - Eros Lazzerini Denchi
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD 20892, U.S.A
| | - Gianna M Tricola
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD 20892, U.S.A
| | - Benura Azeroglu
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD 20892, U.S.A
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2
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Sohn EJ, Goralsky JA, Shay JW, Min J. The Molecular Mechanisms and Therapeutic Prospects of Alternative Lengthening of Telomeres (ALT). Cancers (Basel) 2023; 15:cancers15071945. [PMID: 37046606 PMCID: PMC10093677 DOI: 10.3390/cancers15071945] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 03/14/2023] [Accepted: 03/15/2023] [Indexed: 04/14/2023] Open
Abstract
As detailed by the end replication problem, the linear ends of a cell's chromosomes, known as telomeres, shorten with each successive round of replication until a cell enters into a state of growth arrest referred to as senescence. To maintain their immortal proliferation capacity, cancer cells must employ a telomere maintenance mechanism, such as telomerase activation or the Alternative Lengthening of Telomeres pathway (ALT). With only 10-15% of cancers utilizing the ALT mechanism, progress towards understanding its molecular components and associated hallmarks has only recently been made. This review analyzes the advances towards understanding the ALT pathway by: (1) detailing the mechanisms associated with engaging the ALT pathway as well as (2) identifying potential therapeutic targets of ALT that may lead to novel cancer therapeutic treatments. Collectively, these studies indicate that the ALT molecular mechanisms involve at least two distinct pathways induced by replication stress and damage at telomeres. We suggest exploiting tumor dependency on ALT is a promising field of study because it suggests new approaches to ALT-specific therapies for cancers with poorer prognosis. While substantial progress has been made in the ALT research field, additional progress will be required to realize these advances into clinical practices to treat ALT cancers and improve patient prognoses.
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Affiliation(s)
- Eric J Sohn
- Institute for Cancer Genetics, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Julia A Goralsky
- Institute for Cancer Genetics, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Jerry W Shay
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9039, USA
| | - Jaewon Min
- Institute for Cancer Genetics, Columbia University Irving Medical Center, New York, NY 10032, USA
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY 10032, USA
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3
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Heaphy CM, Singhi AD. Reprint of: The Diagnostic and Prognostic Utility of Incorporating DAXX, ATRX, and Alternative Lengthening of Telomeres (ALT) to the Evaluation of Pancreatic Neuroendocrine Tumors (PanNETs). Hum Pathol 2023; 132:1-11. [PMID: 36702689 DOI: 10.1016/j.humpath.2023.01.004] [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: 07/14/2022] [Accepted: 07/15/2022] [Indexed: 01/26/2023]
Abstract
Pancreatic neuroendocrine tumors (PanNETs) are a heterogeneous group of neoplasms with increasing incidence and an ill-defined pathobiology. Although many PanNETs are indolent and remain stable for years, a subset may behave aggressively and metastasize widely. Thus, the increasing and frequent detection of PanNETs presents a treatment dilemma. Current prognostic systems are susceptible to interpretation errors, sampling issues, and do not accurately reflect the clinical behavior of these neoplasms. Hence, additional biomarkers are needed to improve the prognostic stratification of patients diagnosed with a PanNET. Recent studies have identified alterations in death domain-associated protein 6 (DAXX) and alpha-thalassemia/mental retardation X-linked (ATRX), as well as alternative lengthening of telomeres (ALT), as promising prognostic biomarkers. This review summarizes the identification, clinical utility, and specific nuances in testing for DAXX/ATRX by immunohistochemistry and ALT by telomere-specific fluorescence in situ hybridization in PanNETs. Furthermore, a discussion on diagnostic indications for DAXX, ATRX, and ALT status is provided to include the distinction between PanNETs and pancreatic neuroendocrine carcinomas (PanNECs), and determining pancreatic origin for metastatic neuroendocrine tumors in the setting of an unknown primary.
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Affiliation(s)
- Christopher M Heaphy
- Department of Medicine, Boston University, School of Medicine, Boston, MA, 02118, USA
| | - Aatur D Singhi
- Department of Pathology, University of Pittsburgh Medical Center, Pittsburgh, PA, 15213, USA.
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4
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Yasir S, Thompson S, Chen ZE, Knudson R, Knutson D, Kloft-Nelson S, Graham RP, Jain D, Simon SM, Wu TT, Torbenson M. Alternative lengthening of telomeres in primary hepatic neoplasms. Hum Pathol 2023; 131:79-86. [PMID: 36370823 PMCID: PMC10756352 DOI: 10.1016/j.humpath.2022.11.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 10/31/2022] [Accepted: 11/04/2022] [Indexed: 11/11/2022]
Abstract
The alternative lengthening of telomeres (ALT) phenotype is characterized by ultra-bright telomeres on fluorescence in situ hybridization (FISH) and is a marker of a unique mechanism of telomere maintenance in tumors. ALT does not occur in normal tissues. ALT has been described in hepatocellular carcinoma (5-10%) and in primary hepatic angiosarcomas (75%). To study the frequency of ALT in other primary hepatic tumors, a wide range of primary hepatic neoplasms were retrieved. The tumors included the following: intrahepatic and hilar cholangiocarcinomas (N = 110), hepatic adenomas (N = 35), hepatocellular carcinomas (N = 30), fibrolamellar carcinomas (n = 11), combined cholangiocarcinoma-hepatocellular carcinomas (N = 8), carcinosarcoma (N = 10), hepatoblastomas (N = 5), hemangiomas (N = 4), angiosarcomas (N = 8), epithelioid hemangioendotheliomas (N = 10), calcified nested stromal epithelial tumor (N = 2), embryonal sarcoma (N = 2), rhabdoid tumor (N = 1), bile duct adenoma (N = 1), and angiomyolipoma (N = 1). For epithelial tumors, ALT-FISH was positive in one carcinosarcoma (10% of cases), one cholangiocarcinoma (1% of cases), and one combined hepatocellular carcinoma-cholangiocarcinoma (13% of cases). In the hepatocellular carcinoma component of both the carcinosarcoma and the combined hepatocellular carcinoma-cholangiocarcinoma, the tumor cells showed patchy marked nuclear pleomorphism akin to that described previously for chromophobe hepatocellular carcinoma, which are typically ALT FISH positive. The ALT-positive cholangiocarcinoma also showed patchy, striking nuclear pleomorphism. For soft tissue tumors, ALT was positive in two angiosarcomas (N = 2; 25% of cases). In summary, this study shows that ALT-FISH is positive in rare carcinosarcomas, cholangiocarcinomas, and combined cholangiocarcinoma-hepatocellular carcinoma. ALT is not a significant mechanism of telomere maintenance in hepatocellular adenomas or fibrolamellar carcinomas and was negative in all other tested primary hepatic neoplasms. ALT-FISH is also positive in a subset of primary hepatic angiosarcomas.
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Affiliation(s)
- Saba Yasir
- Department of Laboratory Medicine and Pathology, Mayo Clinic Rochester, MN, 55905, USA
| | - Scott Thompson
- Department of Radiology, Mayo Clinic Rochester, MN, 55905, USA
| | - Zongming Eric Chen
- Department of Laboratory Medicine and Pathology, Mayo Clinic Rochester, MN, 55905, USA
| | - Ryan Knudson
- Medical Genome Facility, Cytogenetics Core Laboratory, Mayo Clinic Rochester, MN, 55905, USA
| | - Darlene Knutson
- Medical Genome Facility, Cytogenetics Core Laboratory, Mayo Clinic Rochester, MN, 55905, USA
| | - Sara Kloft-Nelson
- Medical Genome Facility, Cytogenetics Core Laboratory, Mayo Clinic Rochester, MN, 55905, USA
| | - Rondell P Graham
- Department of Laboratory Medicine and Pathology, Mayo Clinic Rochester, MN, 55905, USA
| | | | - Sanford M Simon
- Laboratory of Cellular Biophysics, The Rockefeller University, 1230 York Avenue, NY, NY, 10065, USA
| | - Tsung-Teh Wu
- Department of Laboratory Medicine and Pathology, Mayo Clinic Rochester, MN, 55905, USA
| | - Michael Torbenson
- Department of Laboratory Medicine and Pathology, Mayo Clinic Rochester, MN, 55905, USA.
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5
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Apolónio JD, Dias JS, Fernandes MT, Komosa M, Lipman T, Zhang CH, Leão R, Lee D, Nunes NM, Maia AT, Morera JL, Vicioso L, Tabori U, Castelo-Branco P. THOR is a targetable epigenetic biomarker with clinical implications in breast cancer. Clin Epigenetics 2022; 14:178. [PMID: 36529814 PMCID: PMC9759897 DOI: 10.1186/s13148-022-01396-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2022] [Accepted: 12/02/2022] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Breast cancer (BC) is the most frequently diagnosed cancer and a leading cause of death among women worldwide. Early BC is potentially curable, but the mortality rates still observed among BC patients demonstrate the urgent need of novel and more effective diagnostic and therapeutic options. Limitless self-renewal is a hallmark of cancer, governed by telomere maintenance. In around 95% of BC cases, this process is achieved by telomerase reactivation through upregulation of the human telomerase reverse transcriptase (hTERT). The hypermethylation of a specific region within the hTERT promoter, termed TERT hypermethylated oncological region (THOR) has been associated with increased hTERT expression in cancer. However, its biological role and clinical potential in BC have never been studied to the best of our knowledge. Therefore, we aimed to investigate the role of THOR as a biomarker and explore the functional impact of THOR methylation status in hTERT upregulation in BC. RESULTS THOR methylation status in BC was assessed by pyrosequencing on discovery and validation cohorts. We found that THOR is significantly hypermethylated in malignant breast tissue when compared to benign tissue (40.23% vs. 12.81%, P < 0.0001), differentiating malignant tumor from normal tissue from the earliest stage of disease. Using a reporter assay, the addition of unmethylated THOR significantly reduced luciferase activity by an average 1.8-fold when compared to the hTERT core promoter alone (P < 0.01). To further investigate its biological impact on hTERT transcription, targeted THOR demethylation was performed using novel technology based on CRISPR-dCas9 system and significant THOR demethylation was achieved. Cells previously demethylated on THOR region did not develop a histologic cancer phenotype in in vivo assays. Additional studies are required to validate these observations and to unravel the causality between THOR hypermethylation and hTERT upregulation in BC. CONCLUSIONS THOR hypermethylation is an important epigenetic mark in breast tumorigenesis, representing a promising biomarker and therapeutic target in BC. We revealed that THOR acts as a repressive regulatory element of hTERT and that its hypermethylation is a relevant mechanism for hTERT upregulation in BC.
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Affiliation(s)
- Joana Dias Apolónio
- grid.7157.40000 0000 9693 350XFaculty of Medicine and Biomedical Sciences (FMCB), University of Algarve, Gambelas Campus, Bld. 2, 8005-139 Faro, Portugal ,grid.7157.40000 0000 9693 350XAlgarve Biomedical Center Research Institute (ABC-RI), University of Algarve, Gambelas Campus, 8005-139 Faro, Portugal ,grid.7157.40000 0000 9693 350XAlgarve Biomedical Center (ABC), University of Algarve, Gambelas Campus, 8005-139 Faro, Portugal ,grid.42327.300000 0004 0473 9646Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON Canada
| | - João S. Dias
- University Hospital Center of Algarve, Faro, Portugal
| | - Mónica Teotónio Fernandes
- grid.7157.40000 0000 9693 350XAlgarve Biomedical Center Research Institute (ABC-RI), University of Algarve, Gambelas Campus, 8005-139 Faro, Portugal ,grid.7157.40000 0000 9693 350XAlgarve Biomedical Center (ABC), University of Algarve, Gambelas Campus, 8005-139 Faro, Portugal ,grid.7157.40000 0000 9693 350XEscola Superior de Saúde (ESSUAlg), Universidade Do Algarve, Faro, Portugal
| | - Martin Komosa
- grid.42327.300000 0004 0473 9646Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON Canada ,grid.17063.330000 0001 2157 2938Arthur and Sonia Labatt Brain Tumor Research Center, The Hospital for Sick Children, University of Toronto, Toronto, ON Canada
| | - Tatiana Lipman
- grid.42327.300000 0004 0473 9646Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON Canada ,grid.17063.330000 0001 2157 2938Arthur and Sonia Labatt Brain Tumor Research Center, The Hospital for Sick Children, University of Toronto, Toronto, ON Canada
| | - Cindy H. Zhang
- grid.42327.300000 0004 0473 9646Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON Canada ,grid.17063.330000 0001 2157 2938Arthur and Sonia Labatt Brain Tumor Research Center, The Hospital for Sick Children, University of Toronto, Toronto, ON Canada
| | - Ricardo Leão
- grid.8051.c0000 0000 9511 4342Faculty of Medicine, University of Coimbra, Coimbra, Portugal
| | - Donghyun Lee
- grid.42327.300000 0004 0473 9646Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON Canada ,grid.17063.330000 0001 2157 2938Arthur and Sonia Labatt Brain Tumor Research Center, The Hospital for Sick Children, University of Toronto, Toronto, ON Canada
| | - Nuno Miguel Nunes
- grid.42327.300000 0004 0473 9646Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON Canada ,grid.17063.330000 0001 2157 2938Arthur and Sonia Labatt Brain Tumor Research Center, The Hospital for Sick Children, University of Toronto, Toronto, ON Canada
| | - Ana-Teresa Maia
- grid.7157.40000 0000 9693 350XFaculty of Medicine and Biomedical Sciences (FMCB), University of Algarve, Gambelas Campus, Bld. 2, 8005-139 Faro, Portugal ,grid.7157.40000 0000 9693 350XAlgarve Biomedical Center (ABC), University of Algarve, Gambelas Campus, 8005-139 Faro, Portugal ,grid.7157.40000 0000 9693 350XCenter for Research in Health Technologies and Information Systems (CINTESIS@RISE), University of Algarve, Gambelas Campus, 8005-139 Faro, Portugal
| | | | - Luis Vicioso
- grid.10215.370000 0001 2298 7828Faculty of Medicine, Department of Histology and Pathological Anatomy, University of Malaga, Malaga, Spain
| | - Uri Tabori
- grid.42327.300000 0004 0473 9646Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON Canada ,grid.17063.330000 0001 2157 2938Arthur and Sonia Labatt Brain Tumor Research Center, The Hospital for Sick Children, University of Toronto, Toronto, ON Canada ,grid.42327.300000 0004 0473 9646Division of Hematology/Oncology, The Hospital for Sick Children, Toronto, ON Canada
| | - Pedro Castelo-Branco
- grid.7157.40000 0000 9693 350XFaculty of Medicine and Biomedical Sciences (FMCB), University of Algarve, Gambelas Campus, Bld. 2, 8005-139 Faro, Portugal ,grid.7157.40000 0000 9693 350XAlgarve Biomedical Center Research Institute (ABC-RI), University of Algarve, Gambelas Campus, 8005-139 Faro, Portugal ,grid.7157.40000 0000 9693 350XAlgarve Biomedical Center (ABC), University of Algarve, Gambelas Campus, 8005-139 Faro, Portugal ,grid.421010.60000 0004 0453 9636Champalimaud Research Program, Champalimaud Centre for the Unknown, Lisbon, Portugal
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6
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Heaphy CM, Singhi AD. The diagnostic and prognostic utility of incorporating DAXX, ATRX, and alternative lengthening of telomeres to the evaluation of pancreatic neuroendocrine tumors. Hum Pathol 2022; 129:11-20. [PMID: 35872157 DOI: 10.1016/j.humpath.2022.07.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 07/15/2022] [Indexed: 12/14/2022]
Abstract
Pancreatic neuroendocrine tumors (PanNETs) are a heterogeneous group of neoplasms with increasing incidence and an ill-defined pathobiology. Although many PanNETs are indolent and remain stable for years, a subset may behave aggressively and metastasize widely. Thus, the increasing and frequent detection of PanNETs presents a treatment dilemma. Current prognostic systems are susceptible to interpretation errors, sampling issues, and do not accurately reflect the clinical behavior of these neoplasms. Hence, additional biomarkers are needed to improve the prognostic stratification of patients diagnosed with a PanNET. Recent studies have identified alterations in death domain-associated protein 6 (DAXX) and alpha-thalassemia/mental retardation X-linked (ATRX), as well as alternative lengthening of telomeres (ALT), as promising prognostic biomarkers. This review summarizes the identification, clinical utility, and specific nuances in testing for DAXX/ATRX by immunohistochemistry and ALT by telomere-specific fluorescence in situ hybridization in PanNETs. Furthermore, a discussion on diagnostic indications for DAXX, ATRX, and ALT status is provided to include the distinction between PanNETs and pancreatic neuroendocrine carcinomas (PanNECs), and determining pancreatic origin for metastatic neuroendocrine tumors in the setting of an unknown primary.
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Affiliation(s)
- Christopher M Heaphy
- Department of Medicine, Boston University, School of Medicine, Boston, MA, 02118, USA
| | - Aatur D Singhi
- Department of Pathology, University of Pittsburgh Medical Center, Pittsburgh, PA, 15213, USA.
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7
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Telomerase in Cancer: Function, Regulation, and Clinical Translation. Cancers (Basel) 2022; 14:cancers14030808. [PMID: 35159075 PMCID: PMC8834434 DOI: 10.3390/cancers14030808] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 01/29/2022] [Accepted: 02/02/2022] [Indexed: 02/04/2023] Open
Abstract
Simple Summary Cells undergoing malignant transformation must circumvent replicative senescence and eventual cell death associated with progressive telomere shortening that occurs through successive cell division. To do so, malignant cells reactivate telomerase to extend their telomeres and achieve cellular immortality, which is a “Hallmark of Cancer”. Here we review the telomere-dependent and -independent functions of telomerase in cancer, as well as its potential as a biomarker and therapeutic target to diagnose and treat cancer patients. Abstract During the process of malignant transformation, cells undergo a series of genetic, epigenetic, and phenotypic alterations, including the acquisition and propagation of genomic aberrations that impart survival and proliferative advantages. These changes are mediated in part by the induction of replicative immortality that is accompanied by active telomere elongation. Indeed, telomeres undergo dynamic changes to their lengths and higher-order structures throughout tumor formation and progression, processes overseen in most cancers by telomerase. Telomerase is a multimeric enzyme whose function is exquisitely regulated through diverse transcriptional, post-transcriptional, and post-translational mechanisms to facilitate telomere extension. In turn, telomerase function depends not only on its core components, but also on a suite of binding partners, transcription factors, and intra- and extracellular signaling effectors. Additionally, telomerase exhibits telomere-independent regulation of cancer cell growth by participating directly in cellular metabolism, signal transduction, and the regulation of gene expression in ways that are critical for tumorigenesis. In this review, we summarize the complex mechanisms underlying telomere maintenance, with a particular focus on both the telomeric and extratelomeric functions of telomerase. We also explore the clinical utility of telomeres and telomerase in the diagnosis, prognosis, and development of targeted therapies for primary, metastatic, and recurrent cancers.
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8
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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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9
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MacKenzie D, Watters AK, To JT, Young MW, Muratori J, Wilkoff MH, Abraham RG, Plummer MM, Zhang D. ALT Positivity in Human Cancers: Prevalence and Clinical Insights. Cancers (Basel) 2021; 13:2384. [PMID: 34069193 PMCID: PMC8156225 DOI: 10.3390/cancers13102384] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 05/07/2021] [Accepted: 05/11/2021] [Indexed: 02/08/2023] Open
Abstract
Many exciting advances in cancer-related telomere biology have been made in the past decade. Of these recent advances, great progress has also been made with respect to the Alternative Lengthening of Telomeres (ALT) pathway. Along with a better understanding of the molecular mechanism of this unique telomere maintenance pathway, many studies have also evaluated ALT activity in various cancer subtypes. We first briefly review and assess a variety of commonly used ALT biomarkers. Then, we provide both an update on ALT-positive (ALT+) tumor prevalence as well as a systematic clinical assessment of the presently studied ALT+ malignancies. Additionally, we discuss the pathogenetic alterations in ALT+ cancers, for example, the mutation status of ATRX and DAXX, and their correlations with the activation of the ALT pathway. Finally, we highlight important ALT+ clinical associations within each cancer subtype and subdivisions within, as well as their prognoses. We hope this alternative perspective will allow scientists, clinicians, and drug developers to have greater insight into the ALT cancers so that together, we may develop more efficacious treatments and improved management strategies to meet the urgent needs of cancer patients.
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Affiliation(s)
| | | | | | | | | | | | | | - Maria M. Plummer
- Department of Biomedical Sciences, College of Osteopathic Medicine, New York Institute of Technology, Old Westbury, NY 11568, USA; (D.M.J.); (A.K.W.); (J.T.T.); (M.W.Y.); (J.M.); (M.H.W.); (R.G.A.)
| | - Dong Zhang
- Department of Biomedical Sciences, College of Osteopathic Medicine, New York Institute of Technology, Old Westbury, NY 11568, USA; (D.M.J.); (A.K.W.); (J.T.T.); (M.W.Y.); (J.M.); (M.H.W.); (R.G.A.)
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10
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da Silva GG, Morais KS, Arcanjo DS, de Oliveira DM. Clinical Relevance of Alternative Lengthening of Telomeres in Cancer. Curr Top Med Chem 2020; 20:485-497. [PMID: 31924155 DOI: 10.2174/1568026620666200110112854] [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: 09/29/2019] [Revised: 12/11/2019] [Accepted: 12/16/2019] [Indexed: 11/22/2022]
Abstract
The alternative lengthening of telomere (ALT) is a pathway responsible for cell immortalization in some kinds of tumors. Since the first description of ALT is relatively recent in the oncology field, its mechanism remains elusive, but recent works address ALT-related proteins or cellular structures as potential druggable targets for more specific and efficient antitumor therapies. Moreover, some new generation compounds for antitelomerase therapy in cancer were able to provoke acquisition of ALT phenotype in treated tumors, enhancing the importance of studies on this alternative lengthening of the telomere. However, ALT has been implicated in different - sometimes opposite - outcomes, according to the tumor type studied. Then, in order to design and develop new drugs for ALT+ cancer in an effective way, it is crucial to understand its clinical implications. In this review, we gathered works published in the last two decades to highlight the clinical relevance of ALT on oncology.
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Affiliation(s)
- Guilherme G da Silva
- Department of Biological Basis of Health Sciences, University of Brasilia, Ceilandia Campus, Federal District, Brazil
| | - Karollyne S Morais
- Laboratory of Molecular Pathology of Cancer, University of Brasilia, Federal District, Brazil
| | - Daniel S Arcanjo
- Department of Biological Basis of Health Sciences, University of Brasilia, Ceilandia Campus, Federal District, Brazil
| | - Diêgo M de Oliveira
- Department of Biological Basis of Health Sciences, University of Brasilia, Ceilandia Campus, Federal District, Brazil.,Laboratory of Molecular Pathology of Cancer, University of Brasilia, Federal District, Brazil
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11
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Robinson NJ, Morrison-Smith CD, Gooding AJ, Schiemann BJ, Jackson MW, Taylor DJ, Schiemann WP. SLX4IP and telomere dynamics dictate breast cancer metastasis and therapeutic responsiveness. Life Sci Alliance 2020; 3:3/4/e201900427. [PMID: 32071280 PMCID: PMC7032570 DOI: 10.26508/lsa.201900427] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 02/10/2020] [Accepted: 02/11/2020] [Indexed: 02/06/2023] Open
Abstract
An unbiased genetic screen established SLX4IP as an essential driver of telomere maintenance mechanism identity, metastatic progression, and therapeutic response of breast cancers. Metastasis is the leading cause of breast cancer-related death and poses a substantial clinical burden owing to a paucity of targeted treatment options. The clinical manifestations of metastasis occur years-to-decades after initial diagnosis and treatment because disseminated tumor cells readily evade detection and resist therapy, ultimately giving rise to recurrent disease. Using an unbiased genetic screen, we identified SLX4-interacting protein (SLX4IP) as a regulator of metastatic recurrence and established its relationship in governing telomere maintenance mechanisms (TMMs). Inactivation of SLX4IP suppressed alternative lengthening of telomeres (ALT), coinciding with activation of telomerase. Importantly, TMM selection dramatically influenced metastatic progression and survival of patients with genetically distinct breast cancer subtypes. Notably, pharmacologic and genetic modulation of TMMs elicited telomere-dependent cell death and prevented disease recurrence by disseminated tumor cells. This study illuminates SLX4IP as a potential predictive biomarker for breast cancer progression and metastatic relapse. SLX4IP expression correlates with TMM identity, which also carries prognostic value and informs treatment selection, thereby revealing new inroads into combating metastatic breast cancers.
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Affiliation(s)
- Nathaniel J Robinson
- Department of Pathology, Case Western Reserve University School of Medicine, Cleveland, OH, USA
| | | | - Alex J Gooding
- Department of Pathology, Case Western Reserve University School of Medicine, Cleveland, OH, USA
| | - Barbara J Schiemann
- Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH, USA
| | - Mark W Jackson
- Department of Pathology, Case Western Reserve University School of Medicine, Cleveland, OH, USA
| | - Derek J Taylor
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, OH, USA
| | - William P Schiemann
- Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH, USA
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12
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Fresques T, Zirbes A, Shalabi S, Samson S, Preto S, Stampfer MR, LaBarge MA. Breast Tissue Biology Expands the Possibilities for Prevention of Age-Related Breast Cancers. Front Cell Dev Biol 2019; 7:174. [PMID: 31555644 PMCID: PMC6722426 DOI: 10.3389/fcell.2019.00174] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Accepted: 08/12/2019] [Indexed: 12/24/2022] Open
Abstract
Preventing breast cancer before it is able to form is an ideal way to stop breast cancer. However, there are limited existing options for prevention of breast cancer. Changes in the breast tissue resulting from the aging process contribute to breast cancer susceptibility and progression and may therefore provide promising targets for prevention. Here, we describe new potential targets, immortalization and inflammaging, that may be useful for prevention of age-related breast cancers. We also summarize existing studies of warfarin and metformin, current drugs used for non-cancerous diseases, that also may be repurposed for breast cancer prevention.
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Affiliation(s)
- Tara Fresques
- Department of Biological Systems and Engineering, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
| | - Arrianna Zirbes
- Department of Population Sciences, Beckman Research Institute at City of Hope, Duarte, CA, United States.,Center for Cancer and Aging Research, Beckman Research Institute at City of Hope, Duarte, CA, United States
| | - Sundus Shalabi
- Department of Population Sciences, Beckman Research Institute at City of Hope, Duarte, CA, United States.,Center for Cancer and Aging Research, Beckman Research Institute at City of Hope, Duarte, CA, United States.,Medical Research Center, Al-Quds University, Jerusalem, Palestine
| | - Susan Samson
- Breast Science Advocacy Core, Breast Oncology Program, University of California, San Francisco, San Francisco, CA, United States
| | | | - Martha R Stampfer
- Department of Biological Systems and Engineering, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
| | - Mark A LaBarge
- Department of Biological Systems and Engineering, Lawrence Berkeley National Laboratory, Berkeley, CA, United States.,Department of Population Sciences, Beckman Research Institute at City of Hope, Duarte, CA, United States.,Center for Cancer and Aging Research, Beckman Research Institute at City of Hope, Duarte, CA, United States
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13
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Lan L, Xu B, Chen Q, Jiang J, Shen Y. Weighted correlation network analysis of triple-negative breast cancer progression: Identifying specific modules and hub genes based on the GEO and TCGA database. Oncol Lett 2019; 18:1207-1217. [PMID: 31423181 PMCID: PMC6607224 DOI: 10.3892/ol.2019.10407] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 01/16/2019] [Indexed: 01/24/2023] Open
Abstract
Triple-negative breast cancer (TNBC) represents an aggressive malignancy of frequent high histologic grade with no effective specific targeted therapies. The present study aimed to identify specific modules and hub genes that may influence the progression of TNBC. The key words ‘breast cancer’ were used to search microarray datasets in the Gene Expression Omnibus and The Cancer Genome Atlas databases that included 5 datasets. A total of 11 co-expression modules were constructed based on the expression levels of 5,782 genes obtained from 456 patients with TNBC using the weighted correlation network analysis (WGCNA). The results demonstrated that the red module was significantly associated with relapse-free survival (RFS) in patients with TNBC [hazard ratio (HR)=0.381, 95% confidence interval (CI), 0.183–0.793; P=0.010]. The functional enrichment analysis revealed that the biological processes corresponding to the red module were ‘mRNA processing’, ‘histone lysine methylation’ and ‘regulation of TOR signaling’. In addition, Hedgehog signaling pathways were considered to serve a critical role in the development of this disease (P<0.001). A total of 12 hub genes were identified, of which α-thalassemia/mental retardation syndrome X-linked (ATRX) was significantly associated with RFS in patients with TNBC (HR=0.601; 95%CI, 0.376–0.960; P=0.033). The receiver operating characteristic curve indicated that ATRX could distinguish relapse from non-relapse in patients with TNBC (area under the curve=0.570; P=0.023). In conclusion, the present study demonstrated that ATRX was associated with TNBC progression, which suggested that ATRX may be involved in a recombination-mediated telomere maintenance mechanism.
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Affiliation(s)
- Lei Lan
- Jiangsu Key Laboratory of Preventive and Translational Medicine for Geriatric Diseases, Department of Epidemiology and Biostatistics, School of Public Health, Soochow University, Suzhou, Jiangsu 215123, P.R. China
| | - Bin Xu
- Department of Tumor Biological Treatment, The Third Affiliated Hospital of Soochow University, Changzhou, Jiangsu 213000, P.R. China.,Jiangsu Engineering Research Center for Tumor Immunotherapy, The Third Affiliated Hospital of Soochow University, Changzhou, Jiangsu 213000, P.R. China
| | - Qu Chen
- Jiangsu Key Laboratory of Preventive and Translational Medicine for Geriatric Diseases, Department of Epidemiology and Biostatistics, School of Public Health, Soochow University, Suzhou, Jiangsu 215123, P.R. China
| | - Jingting Jiang
- Department of Tumor Biological Treatment, The Third Affiliated Hospital of Soochow University, Changzhou, Jiangsu 213000, P.R. China.,Jiangsu Engineering Research Center for Tumor Immunotherapy, The Third Affiliated Hospital of Soochow University, Changzhou, Jiangsu 213000, P.R. China
| | - Yueping Shen
- Jiangsu Key Laboratory of Preventive and Translational Medicine for Geriatric Diseases, Department of Epidemiology and Biostatistics, School of Public Health, Soochow University, Suzhou, Jiangsu 215123, P.R. China
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14
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Robinson NJ, Taylor DJ, Schiemann WP. Stem cells, immortality, and the evolution of metastatic properties in breast cancer: telomere maintenance mechanisms and metastatic evolution. JOURNAL OF CANCER METASTASIS AND TREATMENT 2019; 5:39. [PMID: 31440584 PMCID: PMC6706062 DOI: 10.20517/2394-4722.2019.15] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Breast cancer is the most significant cause of cancer-related death in women around the world. The vast majority of breast cancer-associated mortality stems from metastasis, which remains an incurable disease state. Metastasis results from evolution of clones that possess the insidious properties required for dissemination and colonization of distant organs. These clonal populations are descended from breast cancer stem cells (CSCs), which are also responsible for their prolonged maintenance and continued evolution. Telomeres impose a lifespan on cells that can be extended when they are actively elongated, as occurs in CSCs. Thus, changes in telomere structure serve to promote the survival of CSCs and subsequent metastatic evolution. The selection of telomere maintenance mechanism (TMM) has important consequences not only for CSC survival and evolution, but also for their coordination of various signaling pathways that choreograph the metastatic cascade. Targeting the telomere maintenance machinery may therefore provide a boon to the treatment of metastatic breast cancer. Here we review the two major TMMs and the roles they play in the development of stem and metastatic breast cancer cells. We also highlight current and future approaches to targeting these mechanisms in clinical settings to alleviate metastatic breast cancers.
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Affiliation(s)
- Nathaniel J. Robinson
- Department of Pathology, Case Western Reserve University
School of Medicine, Cleveland, OH 44106, USA
| | - Derek J. Taylor
- Department of Pharmacology, Case Western Reserve University
School of Medicine, Cleveland, OH 44106, USA
| | - William P. Schiemann
- Case Comprehensive Cancer Center, Case Western Reserve
University, Cleveland, OH 44106 USA
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15
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Wu J, Crowe DL. Molecular and cellular basis of mammary gland fibrosis and cancer risk. Int J Cancer 2018; 144:2239-2253. [PMID: 30450584 DOI: 10.1002/ijc.32000] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Revised: 10/16/2018] [Accepted: 11/07/2018] [Indexed: 11/06/2022]
Abstract
Mammary gland luminal cells are maintained by the proliferation of ER- luminal progenitor (LP) cells. Human breast LP cells exhibit telomere DNA damage, which is associated with mammographic density and increased cancer risk. Telomeric repeat factor 2 (TRF2) protects telomeres from DNA damage response. TRF2 expression is reduced in human breast cancers. We deleted TRF2 expression in mammary gland epithelium. Mammary glands lacking TRF2 expression exhibited increased telomere DNA damage response, histopathological and functional degeneration, and prominent ductal fibrosis. TRF2-deficient mammary tumors exhibited rapid onset and increased proliferation. Tumor derived LP cells failed to form tumors after transplantation. The MSC population was highly tumorigenic and maintained telomeres via the ALT mechanism. Telomere DNA damage response in mammary tumors resulted in p53 dependent ER+ cellular differentiation and sensitivity to anti-estrogen therapy. Our results provide a new in vivo model of mammographic density, stem cell differentiation, cancer risk, and therapeutic sensitivity.
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Affiliation(s)
- Jianchun Wu
- Cancer Biology Program, University of Illinois Cancer Center, Chicago, IL
| | - David L Crowe
- Cancer Biology Program, University of Illinois Cancer Center, Chicago, IL
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16
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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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17
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Eastley N, Ottolini B, Garrido C, Shaw JA, McCulloch TA, Ashford RU, Royle NJ. Telomere maintenance in soft tissue sarcomas. J Clin Pathol 2017; 70:371-377. [PMID: 28183782 PMCID: PMC5484030 DOI: 10.1136/jclinpath-2016-204151] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2016] [Accepted: 12/15/2016] [Indexed: 01/27/2023]
Abstract
Soft tissue sarcomas (STS) are a diverse group of heterogeneous malignant tumours derived from mesenchymal tissues. Over 50 different STS subtypes are recognised by WHO, which show a wide range of different biological behaviours and prognoses. At present, clinicians managing this complex group of tumours face several challenges. This is reflected by the relatively poor outcome of patients with STSs compared with many other solid malignant tumours. These include difficulties securing accurate diagnoses, a lack of effective systemic treatments and absence of any sensitive circulating biomarkers to monitor patients throughout their treatment and follow-up. In order to progress STS's cells must evade the usual cellular proliferative checkpoints, and then activate a telomere maintenance mechanism in order to achieve replicative immortality. The purpose of this review is to provide an overview of STS genetics focusing particularly on these mechanisms. We will also highlight some of the key barriers to improving outcome for patients with STS, and hypothesise how a better understanding of these genetic characteristics may impact on future STS management.
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Affiliation(s)
| | - Barbara Ottolini
- Department of Cancer Studies, University of Leicester, Leicester, UK
| | - Carmen Garrido
- Department of Genetics, University of Leicester, Leicester, UK
| | - Jacqueline A Shaw
- Department of Cancer Studies, University of Leicester, Leicester, UK
| | | | | | - Nicola J Royle
- Department of Genetics, University of Leicester, Leicester, UK
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18
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Robinson NJ, Schiemann WP. Means to the ends: The role of telomeres and telomere processing machinery in metastasis. BIOCHIMICA ET BIOPHYSICA ACTA 2016; 1866:320-329. [PMID: 27768860 PMCID: PMC5138103 DOI: 10.1016/j.bbcan.2016.10.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Revised: 10/12/2016] [Accepted: 10/15/2016] [Indexed: 12/29/2022]
Abstract
Despite significant clinical advancements, cancer remains a leading cause of mortality throughout the world due largely to the process of metastasis and the dissemination of cancer cells from their primary tumor of origin to distant secondary sites. The clinical burden imposed by metastasis is further compounded by a paucity of information regarding the factors that mediate metastatic progression. Linear chromosomes are capped by structures known as telomeres, which dictate cellular lifespan in humans by shortening progressively during successive cell divisions. Although telomere shortening occurs in nearly all somatic cells, telomeres may be elongated via two seemingly disjoint pathways: (i) telomerase-mediated extension, and (ii) homologous recombination-based alternative lengthening of telomeres (ALT). Both telomerase and ALT are activated in various human cancers, with more recent evidence implicating both pathways as potential mediators of metastasis. Here we review the known roles of telomere homeostasis in metastasis and posit a mechanism whereby metastatic activity is determined by a dynamic fluctuation between ALT and telomerase, as opposed to the mere activation of a generic telomere elongation program. Additionally, the pleiotropic nature of the telomere processing machinery makes it an attractive therapeutic target for metastasis, and as such, we also explore the therapeutic implications of our proposed mechanism.
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Affiliation(s)
- Nathaniel J Robinson
- Department of Pathology, Case Western Reserve University, Cleveland, OH 44106, USA
| | - William P Schiemann
- Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH 44106, USA.
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19
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Apte MS, Cooper JP. Life and cancer without telomerase: ALT and other strategies for making sure ends (don't) meet. Crit Rev Biochem Mol Biol 2016; 52:57-73. [PMID: 27892716 DOI: 10.1080/10409238.2016.1260090] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
While most cancer cells rely on telomerase expression/re-activation for linear chromosome maintenance and sustained proliferation, a significant population of cancers (10-15%) employs telomerase-independent strategies, collectively dubbed Alternative Lengthening of Telomeres (ALT). Most ALT cells relax the usual role of telomeres as inhibitors of local homologous recombination while maintaining the ability of telomeres to prohibit local non-homologous end joining reactions. Here we review current concepts surrounding how ALT telomeres achieve this new balance via alterations in chromatin landscape, DNA damage repair processes and handling of telomeric transcription. We also discuss telomerase independent end maintenance strategies utilized by other organisms, including fruitflies and yeasts, to draw parallels and contrasts and highlight additional modes, beyond ALT, that may be available to telomerase-minus cancers. We conclude by commenting on promises and challenges in the development of effective anti-ALT cancer therapies.
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Affiliation(s)
- Manasi S Apte
- a Laboratory of Biochemistry and Molecular Biology , Center for Cancer Research, National Cancer Institute, NIH , Bethesda , MD , USA
| | - Julia Promisel Cooper
- a Laboratory of Biochemistry and Molecular Biology , Center for Cancer Research, National Cancer Institute, NIH , Bethesda , MD , USA
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20
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Kaya Z, Akkiprik M, Karabulut S, Peker I, Gullu Amuran G, Ozmen T, Gulluoglu BM, Kaya H, Ozer A. Comparison of telomere length and insulin-like growth factor-binding protein 7 promoter methylation between breast cancer tissues and adjacent normal tissues in Turkish women. J Clin Lab Anal 2016; 31. [PMID: 27775181 DOI: 10.1002/jcla.22083] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 09/18/2016] [Indexed: 02/03/2023] Open
Abstract
BACKGROUND Both insulin-like growth factor-binding protein 7 (IGFBP7) and telomere length (TL) are associated with proliferation and senescence of human breast cancer. This study assessed the clinical significance of both TL and IGFBP7 methylation status in breast cancer tissues compared with adjacent normal tissues. We also investigated whether IGFBP7 methylation status could be affecting TL. METHODS Telomere length was measured by quantitative PCR to compare tumors with their adjacent normal tissues. The IGFBP7 promoter methylation status was evaluated by methylation-specific PCR and its expression levels were determined by western blotting. RESULTS Telomeres were shorter in tumor tissues compared to controls (P<.0001). The mean TL was higher in breast cancer with invasive ductal carcinoma (IDC; n=72; P=.014) compared with other histological type (n=29), and TL in IDC with HER2 negative (n=53; P=.017) was higher than TL in IDC with HER2 positive (n=19). However, telomeres were shortened in advanced stages and growing tumors. IGFBP7 methylation was observed in 90% of tumor tissues and 59% of controls (P=.0002). Its frequency was significantly higher in IDC compared with invasive mixed carcinoma (IMC; P=.002) and it was not correlated either with protein expression or the other clinicopathological parameters. CONCLUSION These results suggest that IGFBP7 promoter methylation and shorter TL in tumor compared with adjacent tissues may be predictive biomarkers for breast cancer. Telomere maintenance may be indicative of IDC and IDC with HER2 (-) of breast cancer. Further studies with larger number of cases are necessary to verify this association.
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Affiliation(s)
- Zehra Kaya
- Medical Biology Department, School of Medicine, Marmara University, Istanbul, Turkey.,Medical Biology Department, School of Medicine, Yüzüncü Yıl University, Van, Turkey
| | - Mustafa Akkiprik
- Medical Biology Department, School of Medicine, Marmara University, Istanbul, Turkey
| | - Sevgi Karabulut
- Medical Biology Department, School of Medicine, Marmara University, Istanbul, Turkey.,Health Services Vocational School, Bayburt University, Bayburt, Turkey
| | - Irem Peker
- Medical Biology Department, School of Medicine, Marmara University, Istanbul, Turkey
| | - Gokce Gullu Amuran
- Medical Biology Department, School of Medicine, Marmara University, Istanbul, Turkey
| | - Tolga Ozmen
- General Surgery, School of Medicine, Marmara University, Istanbul, Turkey
| | | | - Handan Kaya
- Pathology Department, School of Medicine, Marmara University, Istanbul, Turkey
| | - Ayse Ozer
- Medical Biology Department, School of Medicine, Marmara University, Istanbul, Turkey
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21
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Ennour-Idrissi K, Maunsell E, Diorio C. Telomere Length and Breast Cancer Prognosis: A Systematic Review. Cancer Epidemiol Biomarkers Prev 2016; 26:3-10. [PMID: 27677729 DOI: 10.1158/1055-9965.epi-16-0343] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 08/26/2016] [Accepted: 09/16/2016] [Indexed: 01/12/2023] Open
Abstract
Telomeres ensure genome integrity during replication. Loss of telomeric function leads to cell immortalization and accumulation of genetic alterations. The association of telomere length (TL) with breast cancer prognosis is examined through a systematic review. Electronic databases (MEDLINE, EMBASE, CENTRAL), from inception to December 2015, and relevant reviews were searched. Studies that evaluated TL (blood and/or tumor) in association with breast cancer survival or prognostic factor were included. Thirty-six studies met inclusion criteria. Overall risk of bias was critical. Eight studies reported survival outcomes. Overall, there was a trend toward an association of longer telomeres with better outcomes (tumor, not blood). Of the 33 studies reporting associations with prognostic factors, nine adjusted for potential confounders. Among the latter, shorter telomeres were associated with older age (blood, not tumor), higher local recurrence rates (normal tissue), higher tumor grade (tumor), and lower physical activity (blood), which were reported in one study each. TL was not associated with molecular subtype (blood, one study), family history (tumor, one study), chemotherapy (blood, three of four studies), and stress reduction interventions (blood, two of two studies). Although major methodologic differences preclude from drawing conclusive results, TL could be a valuable breast cancer prognostic marker. Cancer Epidemiol Biomarkers Prev; 26(1); 3-10. ©2016 AACR.
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Affiliation(s)
- Kaoutar Ennour-Idrissi
- Axe Oncologie, Centre de Recherche du CHU de Québec-Université Laval, Québec, Canada.,Centre de Recherche sur le Cancer, Université Laval, Québec, Canada.,Département de Médecine Sociale et Préventive, Faculté de Médecine, Université Laval, Québec, Canada
| | - Elizabeth Maunsell
- Axe Oncologie, Centre de Recherche du CHU de Québec-Université Laval, Québec, Canada.,Centre de Recherche sur le Cancer, Université Laval, Québec, Canada.,Département de Médecine Sociale et Préventive, Faculté de Médecine, Université Laval, Québec, Canada.,Centre des Maladies du Sein Deschênes-Fabia, Hôpital du Saint-Sacrement, Québec, Canada
| | - Caroline Diorio
- Axe Oncologie, Centre de Recherche du CHU de Québec-Université Laval, Québec, Canada. .,Centre de Recherche sur le Cancer, Université Laval, Québec, Canada.,Département de Médecine Sociale et Préventive, Faculté de Médecine, Université Laval, Québec, Canada.,Centre des Maladies du Sein Deschênes-Fabia, Hôpital du Saint-Sacrement, Québec, Canada
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22
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Amorim JP, Santos G, Vinagre J, Soares P. The Role of ATRX in the Alternative Lengthening of Telomeres (ALT) Phenotype. Genes (Basel) 2016; 7:E66. [PMID: 27657132 PMCID: PMC5042396 DOI: 10.3390/genes7090066] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 09/07/2016] [Accepted: 09/12/2016] [Indexed: 12/15/2022] Open
Abstract
Telomeres are responsible for protecting chromosome ends in order to prevent the loss of coding DNA. Their maintenance is required for achieving immortality by neoplastic cells and can occur by upregulation of the telomerase enzyme or through a homologous recombination-associated process, the alternative lengthening of telomeres (ALT). The precise mechanisms that govern the activation of ALT or telomerase in tumor cells are not fully understood, although cellular origin may favor one of the other mechanisms that have been found thus far in mutual exclusivity. Specific mutational events influence ALT activation and maintenance: a unifying frequent feature of tumors that acquire this phenotype are the recurrent mutations of the Alpha Thalassemia/Mental Retardation Syndrome X-Linked (ATRX) or Death-Domain Associated Protein (DAXX) genes. This review summarizes the established criteria about this phenotype: its prevalence, theoretical molecular mechanisms and relation with ATRX, DAXX and other proteins (directly or indirectly interacting and resulting in the ALT phenotype).
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Affiliation(s)
- João P Amorim
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto 4200-135, Portugal.
- Instituto de Patologia e Imunologia Molecular da Universidade do Porto (Ipatimup), Porto 4200-135, Portugal.
- Instituto de Ciências Biomédicas Abel Salazar da Universidade do Porto, Porto 4050-313, Portugal.
| | - Gustavo Santos
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto 4200-135, Portugal.
- Instituto de Patologia e Imunologia Molecular da Universidade do Porto (Ipatimup), Porto 4200-135, Portugal.
- Instituto de Ciências Biomédicas Abel Salazar da Universidade do Porto, Porto 4050-313, Portugal.
| | - João Vinagre
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto 4200-135, Portugal.
- Instituto de Patologia e Imunologia Molecular da Universidade do Porto (Ipatimup), Porto 4200-135, Portugal.
- Instituto de Ciências Biomédicas Abel Salazar da Universidade do Porto, Porto 4050-313, Portugal.
| | - Paula Soares
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto 4200-135, Portugal.
- Instituto de Patologia e Imunologia Molecular da Universidade do Porto (Ipatimup), Porto 4200-135, Portugal.
- Instituto de Ciências Biomédicas Abel Salazar da Universidade do Porto, Porto 4050-313, Portugal.
- Departamento de Patologia e Oncologia, Faculdade de Medicina da Universidade do Porto, Porto 4200-139, Portugal.
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23
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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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24
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Telomere length alterations unique to invasive lobular carcinoma. Hum Pathol 2015; 46:1197-203. [DOI: 10.1016/j.humpath.2015.05.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Revised: 04/30/2015] [Accepted: 05/07/2015] [Indexed: 12/17/2022]
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25
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Garbe JC, Vrba L, Sputova K, Fuchs L, Novak P, Brothman AR, Jackson M, Chin K, LaBarge MA, Watts G, Futscher BW, Stampfer MR. Immortalization of normal human mammary epithelial cells in two steps by direct targeting of senescence barriers does not require gross genomic alterations. Cell Cycle 2015; 13:3423-35. [PMID: 25485586 PMCID: PMC4613853 DOI: 10.4161/15384101.2014.954456] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Telomerase reactivation and immortalization are critical for human carcinoma progression. However, little is known about the mechanisms controlling this crucial step, due in part to the paucity of experimentally tractable model systems that can examine human epithelial cell immortalization as it might occur in vivo. We achieved efficient non-clonal immortalization of normal human mammary epithelial cells (HMEC) by directly targeting the 2 main senescence barriers encountered by cultured HMEC. The stress-associated stasis barrier was bypassed using shRNA to p16INK4; replicative senescence due to critically shortened telomeres was bypassed in post-stasis HMEC by c-MYC transduction. Thus, 2 pathologically relevant oncogenic agents are sufficient to immortally transform normal HMEC. The resultant non-clonal immortalized lines exhibited normal karyotypes. Most human carcinomas contain genomically unstable cells, with widespread instability first observed in vivo in pre-malignant stages; in vitro, instability is seen as finite cells with critically shortened telomeres approach replicative senescence. Our results support our hypotheses that: (1) telomere-dysfunction induced genomic instability in pre-malignant finite cells may generate the errors required for telomerase reactivation and immortalization, as well as many additional “passenger” errors carried forward into resulting carcinomas; (2) genomic instability during cancer progression is needed to generate errors that overcome tumor suppressive barriers, but not required per se; bypassing the senescence barriers by direct targeting eliminated a need for genomic errors to generate immortalization. Achieving efficient HMEC immortalization, in the absence of “passenger” genomic errors, should facilitate examination of telomerase regulation during human carcinoma progression, and exploration of agents that could prevent immortalization.
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Key Words
- BaP, benzo(a)pyrene
- CT, cholera toxin
- DDR, DNA damage response
- DMR, differentially methylated regions
- HMEC, human mammary epithelial cells
- OIS, oncogene-induced senescence
- PD, population doublings
- RB, retinoblastoma protein
- TTS, transcription start site
- X, oxytocin
- c-Myc
- carcinogenesis
- genomic instability
- human mammary epithelial cells
- immortalization
- p, passage
- p16INK4a
- p16sh, shRNA to p16INK4A
- senescence
- telomerase
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Affiliation(s)
- James C Garbe
- a Life Sciences Division ; Lawrence Berkeley National Laboratory ; Berkeley , CA USA
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26
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Reddel RR. Telomere maintenance mechanisms in cancer: clinical implications. Curr Pharm Des 2015; 20:6361-74. [PMID: 24975603 PMCID: PMC4262939 DOI: 10.2174/1381612820666140630101047] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Accepted: 06/26/2014] [Indexed: 01/20/2023]
Abstract
The presence of immortal cell populations with an up-regulated telomere maintenance mechanism (TMM) is an almost universal characteristic of cancers, whereas normal somatic cells are unable to prevent proliferation-associated telomere shortening and have a limited proliferative potential. TMMs and related aspects of telomere structure and function therefore appear to be ideal targets for the development of anticancer therapeutics. Such treatments would be targeted to a specific cancer-related molecular abnormality, and also be broad-spectrum in that they would be expected to be potentially applicable to most cancers. However, the telomere biology of normal and malignant human cells is a relatively young research field with large numbers of unanswered questions, so the optimal design of TMM-targeted therapeutic approaches remains unclear. This review outlines the opportunities and challenges presented by telomeres and TMMs for clinical management of cancer.
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Affiliation(s)
- Roger R Reddel
- Children's Medical Research Institute, 214 Hawkesbury Road, Westmead, New South Wales 2145, Australia.
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27
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Assembly of telomeric chromatin to create ALTernative endings. Trends Cell Biol 2014; 24:675-85. [PMID: 25172551 DOI: 10.1016/j.tcb.2014.07.007] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 07/25/2014] [Accepted: 07/29/2014] [Indexed: 01/09/2023]
Abstract
Circumvention of the telomere length-dependent mechanisms that control the upper boundaries of cellular proliferation is necessary for the unlimited growth of cancer. Most cancer cells achieve cellular immortality by up-regulating the expression of telomerase to extend and maintain their telomere length. However, a small but significant number of cancers do so via the exchange of telomeric DNA between chromosomes in a pathway termed alternative lengthening of telomeres, or ALT. Although it remains to be clarified why a cell chooses the ALT pathway and how ALT is initiated, recently identified mutations in factors that shape the chromatin and epigenetic landscape of ALT telomeres are shedding light on these mechanisms. In this review, we examine these recent findings and integrate them into the current models of the ALT mechanism.
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28
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Xu B, Peng M, Song Q. The co-expression of telomerase and ALT pathway in human breast cancer tissues. Tumour Biol 2013; 35:4087-93. [PMID: 24375252 DOI: 10.1007/s13277-013-1534-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Accepted: 12/11/2013] [Indexed: 12/24/2022] Open
Abstract
Recently, telomerase-targeted therapy was studied intensively; however, many studies have verified the existence of alternative lengthening mechanisms of telomeres in vitro. In the present work, we explored the expression characteristic of the two kinds of telomere-prolonging mechanisms in the breast cancer tissues per se. Furthermore, we studied the relationship between Her-2 expression and ALT pathway. Ninety samples of breast cancer tissues were examined in this research. RT-PCR was used for the detection of the expression of human telomerase reverse transcriptase (hTERT); IHC was used for the detection of the expression of promyelocytic leukemia body (PML) bodies; the co-expression of PML bodies and hTERT was detected using the QDs-based immunofluorescence. The co-expression of PML body and hTERT was found in the same cell in breast cancer tissues, and ten samples expressed neither PML bodies nor hTERT. Additionally, the expression of PML bodies and Her-2 was statistically co-related (P = 0.047). The two kinds of mechanisms of telomere extension can co-exist in the same cell in beast cancer tissues, and there may be other mechanisms of telomere extension functioning in human breast carcinoma.
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Affiliation(s)
- Bin Xu
- Oncology Center, Renmin Hospital of Wuhan University, Wuhan, Hubei, 430060, People's Republic of China
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29
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Durant ST. Telomerase-independent paths to immortality in predictable cancer subtypes. J Cancer 2012; 3:67-82. [PMID: 22315652 PMCID: PMC3273709 DOI: 10.7150/jca.3965] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2011] [Accepted: 01/28/2012] [Indexed: 01/17/2023] Open
Abstract
The vast majority of cancers commandeer the activity of telomerase - the remarkable enzyme responsible for prolonging cellular lifespan by maintaining the length of telomeres at the ends of chromosomes. Telomerase is only normally active in embryonic and highly proliferative somatic cells. Thus, targeting telomerase is an attractive anti-cancer therapeutic rationale currently under investigation in various phases of clinical development. However, previous reports suggest that an average of 10-15% of all cancers lose the functional activity of telomerase and most of these turn to an Alternative Lengthening of Telomeres pathway (ALT). ALT-positive tumours will therefore not respond to anti-telomerase therapies and there is a real possibility that such drugs would be toxic to normal telomerase-utilising cells and ultimately select for resistant cells that activate an ALT mechanism. ALT exploits certain DNA damage response (DDR) components to counteract telomere shortening and rapid trimming. ALT has been reported in many cancer subtypes including sarcoma, gastric carcinoma, central nervous system malignancies, subtypes of kidney (Wilm's Tumour) and bladder carcinoma, mesothelioma, malignant melanoma and germ cell testicular cancers to name but a few. A recent heroic study that analysed ALT in over six thousand tumour samples supports this historical spread, although only reporting an approximate 4% prevalence. This review highlights the various methods of ALT detection, unravels several molecular ALT models thought to promote telomere maintenance and elongation, spotlights the DDR components known to facilitate these and explores why certain tissues are more likely to subvert DDR away from its usually protective functions, resulting in a predictive pattern of prevalence in specific cancer subsets.
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Affiliation(s)
- Stephen T Durant
- AstraZeneca - DNA Damage Response, Bioscience, Oncology iMed, Alderley Park, Cheshire, SK10 4TG, England, UK
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30
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Zhou X, Meeker AK, Makambi KH, Kosti O, Kallakury BVS, Sidawy MK, Loffredo CA, Zheng YL. Telomere length variation in normal epithelial cells adjacent to tumor: potential biomarker for breast cancer local recurrence. Carcinogenesis 2011; 33:113-8. [PMID: 22072619 DOI: 10.1093/carcin/bgr248] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
A better understanding of the risk of local recurrence (LR) will facilitate therapeutic decision making in the management of early breast cancers. In the present study, we investigated whether telomere length in the normal breast epithelial cells surrounding the tumor is predictive of breast cancer LR; 152 women who were diagnosed with breast cancer at the Lombardi Comprehensive Cancer Center were included in this nested case-control study. Cases (patients had LR) and controls (patients had no LR) were matched on year of surgery, age at diagnosis and type of surgery. Telomere fluorescent in situ hybridization was used to determine the telomere length using formalin fixed paraffin-embedded breast tissues. Small telomere length variation (TLV), defined as the coefficient variation of telomere lengths among examined cells, in normal epithelial cells adjacent to the tumor was significantly associated with a 5-fold (95% confidence interval = 1.2-22.2) increased risk of breast cancer LR. When the subjects were categorized into quartiles, a significant inverse dose-response relationship was observed with lowest versus highest quartile odds ratio of 15.3 (P(trend) = 0.012). Patients who had large TLV had significantly better 10 year recurrence free survival rate compared with patients who had small TLV (80 versus 33%). The present study revealed that TLV in normal epithelial cells adjacent to tumor is a strong predictor of breast cancer LR. If confirmed by future studies, TLV in normal epithelial cells adjacent to tumor has the potential to become a promising biomarker for predicting breast cancer LR after breast conserving surgery.
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Affiliation(s)
- Xin Zhou
- Carcinogenesis, Biomarkers and Epidemiology Program, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20057, USA
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31
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Abstract
The role telomeres and telomerase play in the initiation and progression of human cancers has been extensively evaluated. Telomeres are nucleoprotein complexes comprising the hexanucleotide DNA repeat sequence, TTAGGG and numerous telomere-associated proteins, including the six member Shelterin complex. The main function of the telomere is to stabilize the ends of the chromosomes. However, through multiple mechanisms, telomeres can become dysfunctional, which may drive genomic instability leading to the development of cancer. The majority of human cancers maintain, or actively lengthen, telomeres through up-regulation of the reverse transcriptase telomerase. Because there are significant differences in telomere length and telomerase activity between malignant and non-malignant tissues, many investigations have assessed the potential to utilize these molecular markers for cancer diagnosis. Here, we critically evaluate whether measurements of telomere lengths and telomerase levels may be clinically utilized as diagnostic markers in solid tumours, with emphasis on breast and prostate cancer as representative examples. Future directions focusing on the direct detection of dysfunctional telomeres are explored. New markers for telomere dysfunction may eventually prove clinically useful.
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Affiliation(s)
- Christopher M Heaphy
- Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA.
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Prevalence of the alternative lengthening of telomeres telomere maintenance mechanism in human cancer subtypes. THE AMERICAN JOURNAL OF PATHOLOGY 2011; 179:1608-15. [PMID: 21888887 DOI: 10.1016/j.ajpath.2011.06.018] [Citation(s) in RCA: 371] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2011] [Revised: 05/31/2011] [Accepted: 06/14/2011] [Indexed: 12/15/2022]
Abstract
Approximately 10% to 15% of human cancers lack detectable telomerase activity, and a subset of these maintain telomere lengths by the telomerase-independent telomere maintenance mechanism termed alternative lengthening of telomeres (ALT). The ALT phenotype, relatively common in subtypes of sarcomas and astrocytomas, has rarely been reported in epithelial malignancies. However, the prevalence of ALT has not been thoroughly assessed across all cancer types. We therefore comprehensively surveyed the ALT phenotype in a broad range of human cancers. In total, two independent sets comprising 6110 primary tumors from 94 different cancer subtypes, 541 benign neoplasms, and 264 normal tissue samples were assessed by combined telomere-specific fluorescence in situ hybridization and immunofluorescence labeling for PML protein. Overall, ALT was observed in 3.73% (228/6110) of all tumor specimens, but was not observed in benign neoplasms or normal tissues. This is the first report of ALT in carcinomas arising from the bladder, cervix, endometrium, esophagus, gallbladder, kidney, liver, and lung. Additionally, this is the first report of ALT in medulloblastomas, oligodendrogliomas, meningiomas, schwannomas, and pediatric glioblastoma multiformes. Previous studies have shown associations between ALT status and prognosis in some tumor types; thus, further studies are warranted to assess the potential prognostic significance and unique biology of ALT-positive tumors. These findings may have therapeutic consequences, because ALT-positive cancers are predicted to be resistant to anti-telomerase therapies.
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33
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Wang Y, Meeker AK, Kowalski J, Tsai HL, Somervell H, Heaphy C, Sangenario LE, Prasad N, Westra WH, Zeiger MA, Umbricht CB. Telomere length is related to alternative splice patterns of telomerase in thyroid tumors. THE AMERICAN JOURNAL OF PATHOLOGY 2011; 179:1415-24. [PMID: 21763260 DOI: 10.1016/j.ajpath.2011.05.056] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2011] [Revised: 04/19/2011] [Accepted: 05/11/2011] [Indexed: 01/02/2023]
Abstract
Telomere dysfunction and aberrant telomerase expression play important roles in tumorigenesis. In thyroid tumors, three possibly inhibitory splice variants of the active full-length isoform of human telomerase reverse transcriptase (hTERT) may be expressed. These variants might regulate telomerase activity and telomere length because it is the fraction of the full-length isoform, rather than the total transcript level, that correlates with enzymatic activity. Telomerase reactivation may be critical in the early stages of tumorigenesis, when progressive telomere shortening may be limiting cell viability. The aim of this study was to investigate the relationship between telomere length and hTERT splice variant expression patterns in benign and well-differentiated malignant thyroid tumors. Telomere lengths of 61 thyroid tumors were examined by fluorescence in situ hybridization, comparing tumors with adjacent normal thyroid tissue on the same slide. Expression patterns of hTERT splice variants were evaluated by quantitative and nested RT-PCR. Telomere length was inversely correlated with percentage of full-length hTERT expression rather than with total hTERT expression levels. Short telomeres and high fractions of full-length hTERT transcripts were associated with follicular and papillary thyroid carcinomas, whereas long telomeres and low levels of full-length hTERT were associated with benign thyroid nodules. Intermediate levels of full-length hTERT and telomere length were found in follicular variant of papillary thyroid carcinomas and follicular adenomas.
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Affiliation(s)
- Yongchun Wang
- Department of Surgery, The Johns Hopkins Medical Institutions, Baltimore, Maryland, USA
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34
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Heaphy CM, Subhawong AP, Gross AL, Konishi Y, Kouprina N, Argani P, Visvanathan K, Meeker AK. Shorter telomeres in luminal B, HER-2 and triple-negative breast cancer subtypes. Mod Pathol 2011; 24:194-200. [PMID: 21057458 PMCID: PMC4416483 DOI: 10.1038/modpathol.2010.198] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Telomeres are nucleoprotein structures that protect chromosome ends from degradation and recombination. Cancers often have critically shortened telomeres, contributing to genomic instability. Many of these tumors activate telomerase to stabilize telomeric ends and achieve a capacity for unlimited replication. Telomere shortening has been reported in in situ and invasive carcinomas, including breast, and has been associated with disease recurrence after surgical resection. However, previous studies have not evaluated breast cancer subtypes. The objective of this study was to evaluate telomere lengths in different subtypes of breast cancer. Breast carcinomas (n=103) identified between 2001 and 2010 from patients seen at the Johns Hopkins Hospital were categorized into luminal A (n=18), luminal B (n=28), HER-2-positive (n=20) and triple-negative carcinomas (n=37) based on tumor characteristics. Telomere lengths were assessed directly at the single cell level by fluorescence in situ hybridization, and patient groups were compared using Fisher's exact tests. ER-negative status (P=0.022), PR-negative status (P=0.008), HER-2-positive status (P=0.023) and p53-positive status (P=0.022) were associated with shorter telomere length. A larger proportion of luminal A cancers had normal or long telomere lengths as compared with luminal B cases (P=0.002), HER-2-positive cases (P=0.011) or triple-negative cases (P=0.0003). Luminal B, HER-2-positive and triple-negative cases did not differ significantly. Telomere length was shorter in more aggressive subtypes, such as luminal B, HER-2-positive and triple-negative tumors, suggesting that tumor telomere length may have utility as a prognostic and/or risk marker for breast cancer.
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Affiliation(s)
| | | | - Amy L Gross
- Department of Epidemiology, The Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Yuko Konishi
- Department of Pathology, The Johns Hopkins Hospital, Baltimore, MD, USA
| | - Nina Kouprina
- Department of Pathology, The Johns Hopkins Hospital, Baltimore, MD, USA
| | - Pedram Argani
- Department of Pathology, The Johns Hopkins Hospital, Baltimore, MD, USA,Department of Oncology, The Johns Hopkins Hospital, Baltimore, MD, USA
| | - Kala Visvanathan
- Department of Epidemiology, The Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA,Department of Oncology, The Johns Hopkins Hospital, Baltimore, MD, USA
| | - Alan K Meeker
- Department of Pathology, The Johns Hopkins Hospital, Baltimore, MD, USA,Department of Oncology, The Johns Hopkins Hospital, Baltimore, MD, USA,Department of Urology, The Johns Hopkins Hospital, Baltimore, MD, USA
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35
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Zheng YL, Zhou X, Loffredo CA, Shields PG, Sun B. Telomere deficiencies on chromosomes 9p, 15p, 15q and Xp: potential biomarkers for breast cancer risk. Hum Mol Genet 2010; 20:378-86. [PMID: 20956286 DOI: 10.1093/hmg/ddq461] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Although telomere dysfunction is a characteristic of breast cancer cells, the relationship between deficiency on individual chromosomal telomeres in normal somatic cells and breast cancer risk has not been characterized. A case-control study was conducted to examine the associations between individual lengths of 92 telomeres in the human genome and the risk of breast cancer in 204 newly diagnosed breast cancer patients and 236 healthy controls. Chromosome arm-specific telomere lengths were measured by telomere quantitative fluorescent in situ hybridization. Unconditional logistic regression was used to estimate the risk associations. This genome-wide screen identified that shorter telomere lengths on chromosomes Xp and 15p were associated with breast cancer risk in pre-menopausal women, with adjusted odds ratios (aORs) of 2.5 (95% CI = 1.3, 4.8) and 2.6 (1.3, 5.0), respectively. The study also revealed that greater length differences between homologous telomeres on chromosomes 9p, 15p and 15q were associated with breast cancer risk in pre-menopausal women, with aORs of 4.6 (2.3, 9.2), 3.1 (1.6, 6.0) and 2.8 (1.4, 5.4), respectively. When the subjects were categorized into quartiles, a dose-response relationship was observed for all of the above telomeres (P-for-trend ≤ 0.005). This study revealed that telomere deficiencies on chromosomes 9p, 15p, 15q and Xp were associated with breast cancer risk in pre-menopausal women. If confirmed in future studies, chromosomal arm-specific telomeres are likely to be a useful panel of blood-based biomarkers for breast cancer risk assessment, given their strong associations with breast cancer risk.
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Affiliation(s)
- Yun-Ling Zheng
- Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20057, USA.
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36
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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: 176] [Impact Index Per Article: 12.6] [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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37
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Abstract
Unlimited cellular proliferation depends on counteracting the telomere attrition that accompanies DNA replication. In human cancers this usually occurs through upregulation of telomerase activity, but in 10-15% of cancers - including some with particularly poor outcome - it is achieved through a mechanism known as alternative lengthening of telomeres (ALT). ALT, which is dependent on homologous recombination, is therefore an important target for cancer therapy. Although dissection of the mechanism or mechanisms of ALT has been challenging, recent advances have led to the identification of several genes that are required for ALT and the elucidation of the biological significance of some phenotypic markers of ALT. This has enabled development of a rapid assay of ALT activity levels and the construction of molecular models of ALT.
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38
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Abstract
Normal mammalian somatic cells proliferate a finite number of times in vitro before permanently withdrawing from the cell cycle into a cellular state referred to as senescence. Senescence may be triggered by excessive mitogenic stimulation or by various forms of cellular damage including excessive telomere shortening. Over the past decade, there has been continuing accumulation of evidence that senescence occurs in vivo, that it is relevant to aging and that it has a tumor suppressor function. However, the phenotype of senescence has also been found to include a number of puzzling features, including the secretion of proinflammatory factors that may foster tumorigenesis as well as the senescence of neighboring cells. On the basis of these antagonistic pro- and antitumorigenic effects, and of the observation that many viruses have developed proteins that prevent senescence of the cells they infect, it is argued that the primary function of senescence may have been as an antiviral defense mechanism. Recent progress in understanding how tumor cells evade senescence is also reviewed here.
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Affiliation(s)
- Roger R Reddel
- Cancer Research Unit, Children's Medical Research Institute, 214 Hawkesbury Road, Westmead, New South Wales 2145, Australia.
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