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Zhou X, Zhu H, Lu J. PTEN and hTERT gene expression and the correlation with human hepatocellular carcinoma. Pathol Res Pract 2015; 211:316-9. [DOI: 10.1016/j.prp.2014.11.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Accepted: 11/11/2014] [Indexed: 11/29/2022]
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202
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Hernández L, Terradas M, Camps J, Martín M, Tusell L, Genescà A. Aging and radiation: bad companions. Aging Cell 2015; 14:153-61. [PMID: 25645467 PMCID: PMC4364827 DOI: 10.1111/acel.12306] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/02/2014] [Indexed: 01/11/2023] Open
Abstract
Aging involves a deterioration of cell functions and changes that may predispose the cell to undergo an oncogenic transformation. The carcinogenic risks following radiation exposure rise with age among adults. Increasing inflammatory response, loss of oxidant/antioxidant equilibrium, ongoing telomere attrition, decline in the DNA damage response efficiency, and deleterious nuclear organization are age-related cellular changes that trigger a serious threat to genomic integrity. In this review, we discuss the mechanistic interplay between all these factors, providing an integrated view of how they contribute to the observed age-related increase in radiation sensitivity. As life expectancy increases and so it does the medical intervention, it is important to highlight the benefits of radiation protection in the elderly. Thus, a deep understanding of the mechanistic processes confining the threat of aging-related radiosensitivity is currently of foremost relevance.
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Affiliation(s)
- Laia Hernández
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona08193, Bellaterra, Spain
| | - Mariona Terradas
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona08193, Bellaterra, Spain
| | - Jordi Camps
- Gastrointestinal and Pancreatic Oncology Group, Hospital Clínic, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Institut D'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS)08036, Barcelona, Spain
| | - Marta Martín
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona08193, Bellaterra, Spain
| | - Laura Tusell
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona08193, Bellaterra, Spain
| | - Anna Genescà
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona08193, Bellaterra, Spain
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203
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Hermsen R, Toonen P, Kuijk E, Youssef SA, Kuiper R, van Heesch S, de Bruin A, Cuppen E, Simonis M. Lack of major genome instability in tumors of p53 null rats. PLoS One 2015; 10:e0122066. [PMID: 25811670 PMCID: PMC4374866 DOI: 10.1371/journal.pone.0122066] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Accepted: 02/11/2015] [Indexed: 01/20/2023] Open
Abstract
Tumorigenesis is often associated with loss of tumor suppressor genes (such as TP53), genomic instability and telomere lengthening. Previously, we generated and characterized a rat p53 knockout model in which the homozygous rats predominantly develop hemangiosarcomas whereas the heterozygous rats mainly develop osteosarcomas. Using genome-wide analyses, we find that the tumors that arise in the heterozygous and homozygous Tp53C273X mutant animals are also different in their genomic instability profiles. While p53 was fully inactivated in both heterozygous and homozygous knockout rats, tumors from homozygous animals show very limited aneuploidy and low degrees of somatic copy number variation as compared to the tumors from heterozygous animals. In addition, complex structural rearrangements such as chromothripsis and breakage-fusion-bridge cycles were never found in tumors from homozygous animals, while these were readily detectable in tumors from heterozygous animals. Finally, we measured telomere length and telomere lengthening pathway activity and found that tumors of homozygous animals have longer telomeres but do not show clear telomerase or alternative lengthening of telomeres (ALT) activity differences as compared to the tumors from heterozygous animals. Taken together, our results demonstrate that host p53 status in this rat p53 knockout model has a large effect on both tumor type and genomic instability characteristics, where full loss of functional p53 is not the main driver of large-scale structural variations. Our results also suggest that chromothripsis primarily occurs under p53 heterozygous rather than p53 null conditions.
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Affiliation(s)
- Roel Hermsen
- Hubrecht Institute, KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | - Pim Toonen
- Hubrecht Institute, KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | - Ewart Kuijk
- Hubrecht Institute, KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | - Sameh A. Youssef
- Dutch Molecular Pathology Center. Department of Pathobiology, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 1, 3584 CL Utrecht, The Netherlands
| | - Raoul Kuiper
- Dutch Molecular Pathology Center. Department of Pathobiology, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 1, 3584 CL Utrecht, The Netherlands
| | - Sebastiaan van Heesch
- Hubrecht Institute, KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | - Alain de Bruin
- Dutch Molecular Pathology Center. Department of Pathobiology, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 1, 3584 CL Utrecht, The Netherlands
| | - Edwin Cuppen
- Hubrecht Institute, KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
- * E-mail:
| | - Marieke Simonis
- Hubrecht Institute, KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
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204
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Sun B, Wang Y, Kota K, Shi Y, Motlak S, Makambi K, Loffredo CA, Shields PG, Yang Q, Harris CC, Zheng YL. Telomere length variation: A potential new telomere biomarker for lung cancer risk. Lung Cancer 2015; 88:297-303. [PMID: 25840848 DOI: 10.1016/j.lungcan.2015.03.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Revised: 03/08/2015] [Accepted: 03/12/2015] [Indexed: 12/28/2022]
Abstract
OBJECTIVES In this report the associations between telomere length variation (TLV), mean telomere length in blood lymphocytes and lung cancer risk were examined. MATERIALS AND METHODS The study design is case-control. Cases (N=191) were patients newly diagnosed with histologically confirmed non-small cell lung cancer. Controls (N=207) were healthy individuals recruited from the same counties as cases and matched to cases on age and gender. Telomere fluorescent in situ hybridization was used to measure telomere features using short-term cultured blood lymphocytes. Logistic regression was used to estimate the strength of association between telomere features and lung cancer risk. RESULTS Telomere length variation across all chromosomal ends was significantly associated with lung cancer risk; adjusted odds ratios 4.67 [95% confidence interval (CI): 1.46-14.9] and 0.46 (95% CI: 0.25-0.84) for younger (age≤60) and older (age>60) individuals, respectively. TLV and mean telomere length jointly affected lung cancer risk: when comparing individuals with short telomere length and high TLV to those with long telomere length and low TLV, adjusted odd ratios were 8.21 (95% CI: 1.71-39.5) and 0.33 (95% CI: 0.15-0.72) for younger and older individuals, respectively. CONCLUSIONS TLV in blood lymphocytes is significantly associated with lung cancer risk and the associations were modulated by age. TLV in combination with mean telomere length might be useful in identifying high risk population for lung cancer computerized tomography screening.
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Affiliation(s)
- Bing Sun
- Cancer Prevention and Control Program, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC, United States
| | - Ying Wang
- Cancer Prevention and Control Program, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC, United States
| | - Krishna Kota
- Cancer Prevention and Control Program, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC, United States
| | - Yaru Shi
- Cancer Prevention and Control Program, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC, United States
| | - Salaam Motlak
- Cancer Prevention and Control Program, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC, United States
| | - Kepher Makambi
- Cancer Prevention and Control Program, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC, United States; Department of Biostatistics, Bioinformatics, and Biomathematics, Georgetown University Medical Center, Washington, DC, United States
| | - Christopher A Loffredo
- Cancer Prevention and Control Program, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC, United States; Department of Biostatistics, Bioinformatics, and Biomathematics, Georgetown University Medical Center, Washington, DC, United States
| | - Peter G Shields
- James Cancer Hospital, The Ohio State University Wexner Medical Center, Columbus, OH 43220, United States
| | - Qin Yang
- Cancer Biology Division, Department of Radiation Oncology, Washington University School of Medicine, Saint Louis, MO, United States
| | - Curtis C Harris
- Laboratory of Human Carcinogenesis, Center for Cancer Research, National Cancer Institute, Bethesda, MD, United States
| | - Yun-Ling Zheng
- Cancer Prevention and Control Program, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC, United States.
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205
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Jovanovic K, Chetty CJ, Khumalo T, Da Costa Dias B, Ferreira E, Malindisa ST, Caveney R, Letsolo BT, Weiss SFT. Novel patented therapeutic approaches targeting the 37/67 kDa laminin receptor for treatment of cancer and Alzheimer's disease. Expert Opin Ther Pat 2015; 25:567-82. [PMID: 25747044 DOI: 10.1517/13543776.2015.1014802] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
INTRODUCTION The 37/67 kDa high-affinity laminin receptor (laminin receptor precursor/laminin receptor, LRP/LR) is a multi-faceted cellular receptor. It plays a vital role in the malignancy of various cancer types where it is seen to contribute to invasion, adhesion, apoptosis evasion and angiogenesis. Furthermore, it has been found to play an important role in facilitating the processes leading to neurotoxicity in Alzheimer's disease (AD). Various therapeutic options targeting this receptor have been patented with the outlook on application for the treatment/prevention of these diseases. AREAS COVERED The various roles that LRP/LR plays in cancer, AD and infectious diseases caused by viruses and bacteria have been examined in detail and an overview of the current patented therapeutic strategies targeting this receptor is given. EXPERT OPINION Molecular tools directed against LRP/LR, such as antibodies and small interfering RNA, could prove to be effective in the prevention of metastasis and angiogenesis while inducing apoptosis in cancers. Moreover, these strategies could also be applied to AD where LRP/LR is seen to facilitate the production and internalization of the neurotoxic Aβ peptide. This review provides a comprehensive overview of the mechanisms by which LRP/LR is involved in eliciting pathogenic events, while showing how the use of patented approaches targeting this receptor could be used to treat them.
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Affiliation(s)
- Katarina Jovanovic
- University of the Witwatersrand, School of Molecular and Cell Biology , Private Bag 3, Wits 2050, Johannesburg , Republic of South Africa
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206
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Rana C, Piplani H, Vaish V, Nehru B, Sanyal SN. Downregulation of telomerase activity by diclofenac and curcumin is associated with cell cycle arrest and induction of apoptosis in colon cancer. Tumour Biol 2015; 36:5999-6010. [PMID: 25744732 DOI: 10.1007/s13277-015-3276-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Accepted: 02/18/2015] [Indexed: 12/31/2022] Open
Abstract
Uncontrolled cell proliferation is the hallmark of cancer, and cancer cells have typically acquired damage to genes that directly regulate their cell cycles. The synthesis of DNA onto the end of chromosome during the replicative phase of cell cycle by telomerase may be necessary for unlimited proliferation of cells. Telomerase, a ribonucleoprotein enzyme is considered as a universal therapeutic target of cancer because of its preferential expression in cancer cells and its presence in 90 % of tumors. We studied the regulation of telomerase and telomerase reverse transcriptase catalytic subunit (TERT) by diclofenac and curcumin, alone and also in combination, in 1, 2-dimethylhydrazine dihydrochloride-induced colorectal cancer in rats. The relationship of telomerase activity with tumors suppressor proteins (p51, Rb, p21), cell cycle machinery, and apoptosis was also studied. Telomerase is highly expressed in DMH group and its high activity is associated with increased TERT expression. However, telomerase is absent or is present at lower levels in normal tissue. CDK4, CDK2, cyclin D1, and cyclin E are highly expressed in DMH as assessed by RT-PCR, qRT-PCR, Western blot, and immunofluorescence analysis. Diclofenac and curcumin overcome these carcinogenic effects by downregulating telomerase activity, diminishing the expression of TERT, CDK4, CDK2, cyclin D1, and cyclin E. The anticarcinogenic effects shown after the inhibition of telomerase activity by diclofenac and curcumin may be associated with upregulation of tumor suppressor proteins p51, Rb, and p21, whose activation induces the cells cycle arrest and apoptosis.
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Affiliation(s)
- Chandan Rana
- Department of Biophysics, Panjab University, Chandigarh, 160014, India
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207
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Chen Y, Wu Y, Huang X, Qu P, Li G, Jin T, Xing J, He S. Leukocyte telomere length: a novel biomarker to predict the prognosis of glioma patients. J Cancer Res Clin Oncol 2015; 141:1739-47. [PMID: 25702101 DOI: 10.1007/s00432-015-1938-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2015] [Accepted: 02/12/2015] [Indexed: 10/24/2022]
Abstract
PURPOSE Epidemiological studies have demonstrated that leukocyte telomere length is associated with the developing risk of various malignancies, including glioma. However, its prognostic value in glioma patients has never been investigated. METHODS Relative telomere length (RTL) of peripheral blood leukocytes from 301 glioma patients were examined using a real-time PCR-based method. Kaplan-Meier curves and Cox proportional hazards regression model were used to assess the association of RTL with clinical outcomes of patients. To explore the potential mechanism, the immune phenotype of peripheral blood mononuclear cells (PBMCs) and concentrations of several cytokines from another 20 glioma patients were detected by flow cytometry and enzyme-linked immunosorbent assay (ELISA), respectively. The relationship between RTL and immunological characteristics of PBMCs were further analyzed. RESULTS Patients with short RTL showed both poorer overall survival (OS) and progression-free survival (PFS) than those with long RTL. Multivariate Cox regression analysis demonstrated that RTL was an independent prognostic factor for both OS and PFS in glioma patients. Moreover, the effects of RTL on the prognosis of patients exhibited a dose-dependent manner. Stratified analysis showed that the prognostic value of RTL was not affected by host characteristics except for age. In addition, flow cytometry and ELISA analyses indicated that there was no significant association between RTL and frequency of different immune cell subsets or plasma cytokine concentrations. CONCLUSIONS Our study for the first time demonstrates that leukocyte RTL is an independent prognostic marker for glioma patients. The potential mechanism needs further investigation.
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Affiliation(s)
- Yibing Chen
- State Key Laboratory of Cancer Biology and Experimental Teaching Center of Basic Medicine, Fourth Military Medical University, 169 Changle West Road, Xi'an, 710032, Shaanxi, China
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208
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Putative mechanisms responsible for the decline in cancer prevalence during organism senescence. Biogerontology 2015; 16:559-65. [PMID: 25702285 DOI: 10.1007/s10522-015-9559-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2014] [Accepted: 02/13/2015] [Indexed: 12/21/2022]
Abstract
Most scientific literature reports that aging favors the development of cancers. Each type of cancer, however, initiates and evolves differently, and their natural history can start much earlier in life before their clinical manifestations. The incidence of cancers is spread throughout human life span, and is the result of pre- and post-natal aggressions, individual susceptibility, developmental changes that evolve continuously throughout an individual's life, and time of exposure to carcinogens. Finally, during human senescence, the incidence declines for all cancers. Frequently, the progression of cancers is also slower in aged individuals. There are several possible explanations for this decline at the tissue, cell, and molecular levels, which are described here in. It is time to ask why some tumors are characteristic of either the young, the aged, or during the time of a decline in the reproductive period, and finally, why the incidence of cancers declines late during senescence of human beings. These questions need to be addressed before the origin of cancers can be understood.
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209
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Abstract
Ageing is the main risk factor for major non-communicable chronic lung diseases, including chronic obstructive pulmonary disease, most forms of lung cancer and idiopathic pulmonary fibrosis. While the prevalence of these diseases continually increases with age, their respective incidence peaks at different times during the lifespan, suggesting specific effects of ageing on the onset and/or pathogenesis of chronic obstructive pulmonary disease, lung cancer and idiopathic pulmonary fibrosis. Recently, the nine hallmarks of ageing have been defined as cell-autonomous and non-autonomous pathways involved in ageing. Here, we review the available evidence for the involvement of each of these hallmarks in the pathogenesis of chronic obstructive pulmonary disease, lung cancer, or idiopathic pulmonary fibrosis. Importantly, we propose an additional hallmark, “dysregulation of the extracellular matrix”, which we argue acts as a crucial modifier of cell-autonomous changes and functions, and as a key feature of the above-mentioned lung diseases.
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210
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Telomere length in non-neoplastic gastric mucosa and its relationship to H. pylori infection, degree of gastritis, and NSAID use. Clin Exp Med 2015; 16:65-71. [DOI: 10.1007/s10238-014-0335-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Accepted: 12/23/2014] [Indexed: 01/01/2023]
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211
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Pefani DE, O'Neill E. Safeguarding genome stability: RASSF1A tumor suppressor regulates BRCA2 at stalled forks. Cell Cycle 2015; 14:1624-30. [PMID: 25927241 PMCID: PMC4613848 DOI: 10.1080/15384101.2015.1035845] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Accepted: 03/23/2015] [Indexed: 12/27/2022] Open
Abstract
While it has been widely established that defective fork restart after exposure to stress results in increased genomic instability, the importance of fork protection during stalling for safeguarding genomic integrity has recently been fully appreciated. BRCA2, Breast tumor suppressor, has dual functionality promoting not only DNA repair but also preventing DNA lesions at stalled forks. In response to replication stress, BRCA2 recruits RAD51 onto nascent DNA at stalled forks, protecting nascent DNA from nucleolitic cleavage. Phosphorylation of the BRCA2 C-terminal RAD51 binding site by CDK2 promotes RAD51 filament disassembly, leading to nucleolitic cleavage of newly synthesized DNA and compromised fork integrity. Recently we uncovered how the core Hippo pathway components RASSF1A, MST2 and LATS1 regulate CDK2 activity towards BRCA2, in response to fork stalling. In complex with LATS1, CDK2 exhibits reduced kinase activity which results in low levels of pBRCA2-S3291 and stable RAD51 filaments protecting nascent DNA from MRE11 cleavage. In the absence of the RASSF1A/MST2/LATS1/CDK2 pathway increased resection of newly synthesized DNA leads to chromosomal instability and malignant transformation. This function of RASSF1A in stalled replication fork protection adds to the role of RASSF1A as a tumor suppressor and builds up evidence for RASSF1A status and its prognostic and predictive value in cancer.
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Affiliation(s)
| | - Eric O'Neill
- CRUK/MRC Oxford Institute; Department of Oncology; University of Oxford; Oxford, UK
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212
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Abstract
Telomeres form protective caps at the ends of linear chromosomes to prevent nucleolytic degradation, end-to-end fusion, irregular recombination, and chromosomal instability. Telomeres are composed of repetitive DNA sequences (TTAGGG)n in humans, that are bound by specialized telomere binding proteins. Telomeres lose capping function in response to telomere shortening, which occurs during each division of cells that lack telomerase activity-the enzyme that can synthesize telomeres de novo. Telomeres have a dual role in cancer: telomere shortening can lead to induction of chromosomal instability and to the initiation of tumors, however, initiated tumors need to reactivate telomerase in order to stabilize chromosomes and to gain immortal growth capacity. In this review, we summarize current knowledge on the role of telomeres in the maintenance of chromosomal stability and carcinogenesis.
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213
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Kar A, Chowdhury S. Inhibition of telomerase activity by NME2: impact on metastasis suppression? Naunyn Schmiedebergs Arch Pharmacol 2014; 388:235-41. [PMID: 25547372 PMCID: PMC4469096 DOI: 10.1007/s00210-014-1077-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Accepted: 11/25/2014] [Indexed: 12/25/2022]
Abstract
Though anti-metastatic function of non-metastatic 2 (NME2) has been implicated in multiple cancers, mechanisms of metastases control by NME2 are not clearly understood. Recent observations indicating the involvement of telomerase, the ribonucleoprotein required for telomere synthesis, in metastatic outcome are interesting. Notably, though the role of telomerase dysfunction in tumorigenesis is relatively well studied, involvement in metastasis progression is poorly understood. Recent findings demonstrate NME2 presence at telomere ends, association with telomerase, and NME2’s role in inhibition of telomerase activity in cancer cells. These present a novel opportunity to investigate mechanisms underlying NME2-mediated metastasis suppression.
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Affiliation(s)
- Anirban Kar
- Proteomics and Structural Biology Unit, CSIR-Institute of Genomics and Integrative Biology, Mathura Road, New Delhi, 110025, DELHI, India
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214
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Iarovaia OV, Rubtsov M, Ioudinkova E, Tsfasman T, Razin SV, Vassetzky YS. Dynamics of double strand breaks and chromosomal translocations. Mol Cancer 2014; 13:249. [PMID: 25404525 PMCID: PMC4289179 DOI: 10.1186/1476-4598-13-249] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Accepted: 10/30/2014] [Indexed: 12/27/2022] Open
Abstract
Chromosomal translocations are a major cause of cancer. At the same time, the mechanisms that lead to specific chromosomal translocations that associate different gene regions remain largely unknown. Translocations are induced by double strand breaks (DSBs) in DNA. Here we review recent data on the mechanisms of generation, mobility and repair of DSBs and stress the importance of the nuclear organization in this process.
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Affiliation(s)
| | | | | | | | | | - Yegor S Vassetzky
- UMR8126, Université Paris-Sud, CNRS, Institut de cancérologie Gustave Roussy, Villejuif 94805, France.
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215
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Heng HH, Bremer SW, Stevens JB, Horne SD, Liu G, Abdallah BY, Ye KJ, Ye CJ. Chromosomal instability (CIN): what it is and why it is crucial to cancer evolution. Cancer Metastasis Rev 2014; 32:325-40. [PMID: 23605440 DOI: 10.1007/s10555-013-9427-7] [Citation(s) in RCA: 123] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Results of various cancer genome sequencing projects have "unexpectedly" challenged the framework of the current somatic gene mutation theory of cancer. The prevalence of diverse genetic heterogeneity observed in cancer questions the strategy of focusing on contributions of individual gene mutations. Much of the genetic heterogeneity in tumors is due to chromosomal instability (CIN), a predominant hallmark of cancer. Multiple molecular mechanisms have been attributed to CIN but unifying these often conflicting mechanisms into one general mechanism has been challenging. In this review, we discuss multiple aspects of CIN including its definitions, methods of measuring, and some common misconceptions. We then apply the genome-based evolutionary theory to propose a general mechanism for CIN to unify the diverse molecular causes. In this new evolutionary framework, CIN represents a system behavior of a stress response with adaptive advantages but also serves as a new potential cause of further destabilization of the genome. Following a brief review about the newly realized functions of chromosomes that defines system inheritance and creates new genomes, we discuss the ultimate importance of CIN in cancer evolution. Finally, a number of confusing issues regarding CIN are explained in light of the evolutionary function of CIN.
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Affiliation(s)
- Henry H Heng
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, USA,
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216
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Terasawa M, Shinohara A, Shinohara M. Double-strand break repair-adox: Restoration of suppressed double-strand break repair during mitosis induces genomic instability. Cancer Sci 2014; 105:1519-25. [PMID: 25287622 PMCID: PMC4317954 DOI: 10.1111/cas.12551] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Revised: 09/29/2014] [Accepted: 10/01/2014] [Indexed: 12/18/2022] Open
Abstract
Double-strand breaks (DSBs) are one of the severest types of DNA damage. Unrepaired DSBs easily induce cell death and chromosome aberrations. To maintain genomic stability, cells have checkpoint and DSB repair systems to respond to DNA damage throughout most of the cell cycle. The failure of this process often results in apoptosis or genomic instability, such as aneuploidy, deletion, or translocation. Therefore, DSB repair is essential for maintenance of genomic stability. During mitosis, however, cells seem to suppress the DNA damage response and proceed to the next G1 phase, even if there are unrepaired DSBs. The biological significance of this suppression is not known. In this review, we summarize recent studies of mitotic DSB repair and discuss the mechanisms of suppression of DSB repair during mitosis. DSB repair, which maintains genomic integrity in other phases of the cell cycle, is rather toxic to cells during mitosis, often resulting in chromosome missegregation and aberration. Cells have multiple safeguards to prevent genomic instability during mitosis: inhibition of 53BP1 or BRCA1 localization to DSB sites, which is important to promote non-homologous end joining or homologous recombination, respectively, and also modulation of the non-homologous end joining core complex to inhibit DSB repair. We discuss how DSBs during mitosis are toxic and the multiple safeguard systems that suppress genomic instability.
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217
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Kaufer BB, Flamand L. Chromosomally integrated HHV-6: impact on virus, cell and organismal biology. Curr Opin Virol 2014; 9:111-8. [PMID: 25462442 DOI: 10.1016/j.coviro.2014.09.010] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Revised: 09/24/2014] [Accepted: 09/25/2014] [Indexed: 11/16/2022]
Abstract
HHV-6 integrates its genome into telomeres of human chromosomes. Integration can occur in somatic cells or gametes, the latter leading to individuals harboring the HHV-6 genome in every cell. This condition is transmitted to descendants and referred to as inherited chromosomally integrated human herpesvirus 6 (iciHHV-6). Although integration can occur in different chromosomes, it invariably takes place in the telomere region. This integration mechanism represents a way to maintain the virus genome during latency, which is so far unique amongst human herpesviruses. Recent work provides evidence that the integrated HHV-6 genome can be mobilized from the host chromosome, resulting in the onset of disease. Details on required structural determinants, putative integration mechanisms and biological and medical consequences of iciHHV-6 are discussed.
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Affiliation(s)
| | - Louis Flamand
- Division of Infectious and Immune Diseases, CHU de Quebec, Research Center and Department of Microbiology-Infectious Diseases and Immunology, Université Laval, Quebec, Canada.
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218
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A retrospective examination of mean relative telomere length in the Tasmanian Familial Hematological Malignancies Study. Oncol Rep 2014; 33:25-32. [PMID: 25351806 PMCID: PMC4254675 DOI: 10.3892/or.2014.3568] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 10/02/2014] [Indexed: 12/27/2022] Open
Abstract
Telomere length has a biological link to cancer, with excessive telomere shortening leading to genetic instability and resultant malignant transformation. Telomere length is heritable and genetic variants determining telomere length have been identified. Telomere biology has been implicated in the development of hematological malignancies (HMs), therefore, closer examination of telomere length in HMs may provide further insight into genetic etiology of disease development and support for telomere length as a prognostic factor in HMs. We retrospectively examined mean relative telomere length in the Tasmanian Familial Hematological Malignancies Study using a quantitative PCR method on genomic DNA from peripheral blood samples. Fifty-five familial HM cases, 191 unaffected relatives of familial HM cases and 75 non-familial HM cases were compared with 758 population controls. Variance components modeling was employed to identify factors influencing variation in telomere length. Overall, HM cases had shorter mean relative telomere length (P=2.9×10−6) and this was observed across both familial and non-familial HM cases (P=2.2×10−4 and 2.2×10−5, respectively) as well as additional subgroupings of HM cases according to broad subtypes. Mean relative telomere length was also significantly heritable (62.6%; P=4.7×10−5) in the HM families in the present study. We present new evidence of significantly shorter mean relative telomere length in both familial and non-familial HM cases from the same population adding further support to the potential use of telomere length as a prognostic factor in HMs. Whether telomere shortening is the cause of or the result of HMs is yet to be determined, but as telomere length was found to be highly heritable in our HM families this suggests that genetics driving the variation in telomere length is related to HM disease risk.
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219
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Tanaka H, Beam MJ, Caruana K. The presence of telomere fusion in sporadic colon cancer independently of disease stage, TP53/KRAS mutation status, mean telomere length, and telomerase activity. Neoplasia 2014; 16:814-23. [PMID: 25379018 PMCID: PMC4212252 DOI: 10.1016/j.neo.2014.08.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Revised: 08/19/2014] [Accepted: 08/20/2014] [Indexed: 11/25/2022] Open
Abstract
Defects in telomere maintenance can result in telomere fusions that likely play a causative role in carcinogenesis by promoting genomic instability. However, this proposition remains to be fully understood in human colon carcinogenesis. In the present study, the temporal sequence of telomere dysfunction dynamics was delineated by analyzing telomere fusion, telomere length, telomerase activity, hotspot mutations in KRAS or BRAF, and TP53 of tissue samples obtained from 18 colon cancer patients. Our results revealed that both the deficiency of p53 and the shortening of mean telomere length were not necessary for producing telomere fusions in colon tissue. In five cases, telomere fusion was observed even in tissue adjacent to cancerous lesions, suggesting that genomic instability is initiated in pathologically non-cancerous lesions. The extent of mean telomere attrition increased with lymph node invasiveness of tumors, implying that mean telomere shortening correlates with colon cancer progression. Telomerase activity was relatively higher in most cancer tissues containing mutation(s) in KRAS or BRAF and/or TP53 compared to those without these hotspot mutations, suggesting that telomerase could become fully active at the late stage of colon cancer development. Interestingly, the majority of telomere fusion junctions in colon cancer appeared to be a chromatid-type containing chromosome 7q or 12q. In sum, this meticulous correlative study not only highlights the concept that telomere fusion is present in the early stages of cancer regardless of TP53/KRAS mutation status, mean telomere length, and telomerase activity, but also provides additional insights targeting key telomere fusion junctions which may have significant implications for colon cancer diagnoses.
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Affiliation(s)
- Hiromi Tanaka
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, IN, USA
| | - Matthew J Beam
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, IN, USA
| | - Kevin Caruana
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, IN, USA
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220
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García‐Beccaria M, Martínez P, Flores JM, Blasco MA. In vivo role of checkpoint kinase 2 in signaling telomere dysfunction. Aging Cell 2014; 13:810-6. [PMID: 24920220 PMCID: PMC4331747 DOI: 10.1111/acel.12237] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/11/2014] [Indexed: 01/01/2023] Open
Abstract
Checkpoint kinase 2 (CHK2) is a downstream effector of the DNA damage response (DDR). Dysfunctional telomeres, either owing to critical shortening or disruption of the shelterin complex, activate a DDR, which eventually results in cell cycle arrest, senescence and/or apoptosis. Successive generations of telomerase-deficient (Terc) mice show accelerated aging and shorter lifespan due to tissue atrophy and impaired organ regeneration associated to progressive telomere shortening. In contrast, mice deficient for the shelterin component TRF1 in stratified epithelia show a rapid and massive induction of DDR, leading to perinatal lethality and severe skin defects. In both mouse models, p53 deficiency can rescue survival. Here, we set to address the role of CHK2 in signaling telomere dysfunction in both mouse models. To this end, we generated mice doubly deficient for Chk2 and either Terc (Chk2−/−Terc−/−) or Trf1 (Trf1Δ/ΔK5Cre Chk2−/−). We show that Chk2 deletion improves Terc-associated phenotypes, including lifespan and age-associated pathologies. Similarly, Chk2 deficiency partially rescues perinatal mortality and attenuates degenerative pathologies of Trf1Δ/ΔK5Cre mice. In both cases, we show that the effects are mediated by a significant attenuation of p53/p21 signaling pathway. Our results represent the first demonstration of a role for CHK2 in the in vivo signaling of dysfunctional telomeres.
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Affiliation(s)
- María García‐Beccaria
- Molecular Oncology Program Telomeres and Telomerase Group Spanish National Cancer Research Centre (CNIO) Madrid E‐28029Spain
| | - Paula Martínez
- Molecular Oncology Program Telomeres and Telomerase Group Spanish National Cancer Research Centre (CNIO) Madrid E‐28029Spain
| | - Juana M. Flores
- Animal Surgery and Medicine Department Faculty of Veterinary Science Complutense University of Madrid Madrid E‐28040Spain
| | - Maria A. Blasco
- Molecular Oncology Program Telomeres and Telomerase Group Spanish National Cancer Research Centre (CNIO) Madrid E‐28029Spain
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221
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Rybanska-Spaeder I, Ghosh R, Franco S. 53BP1 mediates the fusion of mammalian telomeres rendered dysfunctional by DNA-PKcs loss or inhibition. PLoS One 2014; 9:e108731. [PMID: 25264618 PMCID: PMC4181871 DOI: 10.1371/journal.pone.0108731] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Accepted: 09/04/2014] [Indexed: 12/21/2022] Open
Abstract
Telomere dysfunction promotes genomic instability and carcinogenesis via inappropriate end-to-end chromosomal rearrangements, or telomere fusions. Previous work indicates that the DNA Damage Response (DDR) factor 53BP1 promotes the fusion of telomeres rendered dysfunctional by loss of TRF2, but is dispensable for the fusion of telomeres lacking Pot1 or critically shortened (in telomerase-deficient mice). Here, we examine a role for 53BP1 at telomeres rendered dysfunctional by loss or catalytic inhibition of DNA-PKcs. Using mouse embryonic fibroblasts lacking 53BP1 and/or DNA-PKcs, we show that 53BP1 deficiency suppresses G1-generated telomere fusions that normally accumulate in DNA-PKcs-deficient fibroblasts with passage. Likewise, we find that 53BP1 promotes telomere fusions during the replicative phases of the cell cycle in cells treated with the specific DNA-PKcs inhibitor NU7026. However, telomere fusions are not fully abrogated in DNA-PKcs-inhibited 53BP1-deficient cells, but occur with a frequency approximately 10-fold lower than in control 53BP1-proficient cells. Treatment with PARP inhibitors or PARP1 depletion abrogates residual fusions, while Ligase IV depletion has no measurable effect, suggesting that PARP1-dependent alternative end-joining operates at low efficiency at 53BP1-deficient, DNA-PKcs-inhibited telomeres. Finally, we have also examined the requirement for DDR factors ATM, MDC1 or H2AX in this context. We find that ATM loss or inhibition has no measurable effect on the frequency of NU7026-induced fusions in wild-type MEFs. Moreover, analysis of MEFs lacking both ATM and 53BP1 indicates that ATM is also dispensable for telomere fusions via PARP-dependent end-joining. In contrast, loss of either MDC1 or H2AX abrogates telomere fusions in response to DNA-PKcs inhibition, suggesting that these factors operate upstream of both 53BP1-dependent and -independent telomere rejoining. Together, these experiments define a novel requirement for 53BP1 in the fusions of DNA-PKcs-deficient telomeres throughout the cell cycle and uncover a Ligase IV-independent, PARP1-dependent pathway that fuses telomeres at reduced efficiency in the absence of 53BP1.
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Affiliation(s)
- Ivana Rybanska-Spaeder
- Department of Radiation Oncology and Molecular Radiation Sciences; and Department of Oncology; and the Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Rajib Ghosh
- Department of Radiation Oncology and Molecular Radiation Sciences; and Department of Oncology; and the Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Sonia Franco
- Department of Radiation Oncology and Molecular Radiation Sciences; and Department of Oncology; and the Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
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Abstract
Our understanding of the pathophysiology of aplastic anemia is undergoing significant revision, with implications for diagnosis and treatment. Constitutional and acquired disease is poorly delineated, as lesions in some genetic pathways cause stereotypical childhood syndromes and also act as risk factors for clinical manifestations in adult life. Telomere diseases are a prominent example of this relationship. Accelerated telomere attrition is the result of mutations in telomere repair genes and genes encoding components of the shelterin complex and related proteins. Genotype-phenotype correlations show genes responsible for X-linked (DKC1) and severe recessive childhood dyskeratosis congenita, typically with associated mucocutaneous features, and others (TERC and TERT) for more subtle presentation as telomeropathy in adults, in which multiorgan failure may be prominent. Telomerase mutations also are etiologic in familial pulmonary fibrosis and cryptic liver disease. Detection of a telomere disease requires awareness in the clinic, appropriate laboratory testing of telomere content, and genetic sequencing. In treatment decisions, genetic screening of related donors for hematopoietic stem cell transplantation is critical, and androgen therapy may be helpful. Telomeres shorten normally with aging, as well as under environmental circumstances, with regenerative stress and oxidative damage. Telomere biology is complexly related to oncogenesis: telomere attrition is protective by enforcing senescence or apoptosis in cells with a long mitotic history, but telomere loss also can destabilize the genome by chromosome rearrangement and aneuploidy.
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223
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Lee JH, Anver M, Kost-Alimova M, Protopopov A, DePinho RA, Rane SG. Telomere dysfunction suppresses multiple endocrine neoplasia in mice. Genes Cancer 2014; 5:306-19. [PMID: 25352948 PMCID: PMC4209601 DOI: 10.18632/genesandcancer.31] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Accepted: 09/05/2014] [Indexed: 11/30/2022] Open
Abstract
Multiple endocrine neoplasia (MEN) syndrome is typified by the occurrence of tumors in two or more hormonal tissues. Whereas the genetics of MEN syndrome is relatively well understood, the tumorigenic mechanisms for these cancers remain relatively obscure. The Cdk4 (R24C) mouse model develops highly penetrant pituitary tumors and endocrine pancreas adenomas, and, as such, this model is appropriate to gain insight into mechanisms underlying MEN. Using this model, here we provide evidence supporting an important role for telomerase in the pathogenesis of MEN. We observed increased aneuploidy in Cdk4 (R/R) fibroblasts along with significantly elevated telomerase activity and telomere length in Cdk4 (R/R) islets and embryonic fibroblasts. To better understand the role of telomerase, we generated Cdk4 (R24C) mice with inactivation of the mTERC locus, which codes for the essential RNA component of the enzyme telomerase (mTERC (-/-) Cdk4 (R/R) mice). Embryonic fibroblasts and islets derived from mTERC (-/-) Cdk4 (R/R) mice exhibit reduced telomere length and proliferative capacity. Further, mTERC (-/-) Cdk4 (R/R) fibroblasts display reduced transformation potential. Importantly, mTERC (-/-) Cdk4 (R/R) mice display significantly reduced spontaneous tumorigenesis. Strikingly, we observed dramatic suppression of pituitary tumors and endocrine pancreas adenomas in mTERC (-/-) Cdk4 (R/R) mice. Telomere dysfunction suppressed tumor initiation and increased latency of tumor development while not affecting the progression of established tumors. In summary, these results are suggestive of an important role for telomerase in tumor development in the Cdk4 (R24C) mouse model, specifically in the genesis of tumors in the pituitary and the endocrine pancreas.
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Affiliation(s)
- Ji-Hyeon Lee
- Diabetes, Endocrinology & Obesity Branch, National Institute of Diabetes & Digestive & Kidney Diseases, Bethesda, MD
| | - Miriam Anver
- Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD
| | - Maria Kost-Alimova
- Dana-Farber Cancer Institute, Boston, MA
- Department of Genomic Medicine, University of Texas MD Anderson Cancer Center, Houston, TX
| | - Alexei Protopopov
- Dana-Farber Cancer Institute, Boston, MA
- Department of Genomic Medicine, University of Texas MD Anderson Cancer Center, Houston, TX
| | - Ronald A. DePinho
- Dana-Farber Cancer Institute, Boston, MA
- Department of Cell Biology, University of Texas MD Anderson Cancer Center, Houston, TX
| | - Sushil G. Rane
- Diabetes, Endocrinology & Obesity Branch, National Institute of Diabetes & Digestive & Kidney Diseases, Bethesda, MD
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Canonical non-homologous end joining in mitosis induces genome instability and is suppressed by M-phase-specific phosphorylation of XRCC4. PLoS Genet 2014; 10:e1004563. [PMID: 25166505 PMCID: PMC4148217 DOI: 10.1371/journal.pgen.1004563] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Accepted: 06/27/2014] [Indexed: 12/22/2022] Open
Abstract
DNA double-strand breaks (DSBs) can be repaired by one of two major pathways-non-homologous end-joining (NHEJ) and homologous recombination (HR)-depending on whether cells are in G1 or S/G2 phase, respectively. However, the mechanisms of DSB repair during M phase remain largely unclear. In this study, we demonstrate that transient treatment of M-phase cells with the chemotherapeutic topoisomerase inhibitor etoposide induced DSBs that were often associated with anaphase bridge formation and genome instability such as dicentric chromosomes. Although most of the DSBs were carried over into the next G1 phase, some were repaired during M phase. Both NHEJ and HR, in particular NHEJ, promoted anaphase-bridge formation, suggesting that these repair pathways can induce genome instability during M phase. On the other hand, C-terminal-binding protein interacting protein (CtIP) suppressed anaphase bridge formation, implying that CtIP function prevents genome instability during mitosis. We also observed M-phase-specific phosphorylation of XRCC4, a regulatory subunit of the ligase IV complex specialized for NHEJ. This phosphorylation required cyclin-dependent kinase (CDK) activity as well as polo-like kinase 1 (Plk1). A phosphorylation-defective XRCC4 mutant showed more efficient M-phase DSB repair accompanied with an increase in anaphase bridge formation. These results suggest that phosphorylation of XRCC4 suppresses DSB repair by modulating ligase IV function to prevent genome instability during M phase. Taken together, our results indicate that XRCC4 is required not only for the promotion of NHEJ during interphase but also for its M-phase-specific suppression of DSB repair.
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225
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Abstract
BACKGROUND The exciting discovery that telomere shortening is associated with many health conditions and that telomere lengths can be altered in response to social and environmental exposures has underscored the need for methods to accurately and consistently quantify telomere length. OBJECTIVES The purpose of this article is to provide a comprehensive summary that compares and contrasts the current technologies used to assess telomere length. DISCUSSION Multiple methods have been developed for the study of telomeres. These techniques include quantification of telomere length by terminal restriction fragmentation-which was one of the earliest tools used for length assessment-making it the gold standard in telomere biology. Quantitative polymerase chain reaction provides the advantage of being able to use smaller amounts of DNA, thereby making it amenable to epidemiology studies involving large numbers of people. An alternative method uses fluorescent probes to quantify not only mean telomere lengths but also chromosome-specific telomere lengths; however, the downside of this approach is that it can only be used on mitotically active cells. Additional methods that permit assessment of the length of a subset of chromosome-specific telomeres or the subset of telomeres that demonstrate shortening are also reviewed. CONCLUSION Given the increased utility for telomere assessments as a biomarker in physiological, psychological, and biobehavioral research, it is important that investigators become familiar with the methodological nuances of the various procedures used for measuring telomere length. This will ensure that they are empowered to select an optimal assessment approach to meet the needs of their study designs. Gaining a better understanding of the benefits and drawbacks of various measurement techniques is important not only in individual studies, but also to further establish the science of telomere associations with biobehavioral phenomena.
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226
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Aref S, El-Ghonemy MS, Abouzeid TE, El-Sabbagh AM, El-Baiomy MA. Telomerase reverse transcriptase (TERT) A1062T mutation as a prognostic factor in Egyptian patients with acute myeloid leukemia (AML). Med Oncol 2014; 31:158. [PMID: 25108601 DOI: 10.1007/s12032-014-0158-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Accepted: 07/30/2014] [Indexed: 01/16/2023]
Abstract
This study aimed to evaluate the incidence and clinical and prognostic impact of TERT A1062T mutation in AML patients treated at Mansoura Oncology Center. Screening for TERT A1062T mutation in exon 15 of the TERT gene was performed on diagnostic DNA samples from 153 AML patients and 197 healthy subjects as a control group by using sequence-specific primers. TERT A1062T mutation was detected in 18 cases out of 153 patients (11.8 %) and in one out of 197 control group subjects (0.51 %). The achievement of complete remission was significantly higher in AML group with wild type as compared to that in the mutant one (53.3 vs 16.7 %, respectively). In addition, the relapse rate was significantly higher in the mutant patients as compared to those with wild type (62.5 vs 28.2 %, respectively). The AML patients with TERT (A1062T) mutation had shorter overall survival than patients with wild type (P = 0.001). In a multivariable analysis, TERT (A1062T) mutational status is independently worse predictor factor (P = 0.007) when controlling for cytogenetic status (P = <0.001), performance status (P = <0.001) and bone marrow blast cells (P = 0.001). In conclusion, TERT A1062T mutation is an independent negative prognostic factor in AML patients. Therefore, molecular testing for TERT A1062T mutation in patients with AML is recommended in order to delineate their prognostic status.
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Affiliation(s)
- Salah Aref
- Hematology Unit, Clinical Pathology Department, Mansoura Faculty of Medicine, Mansoura, Egypt,
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227
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Jones RE, Oh S, Grimstead JW, Zimbric J, Roger L, Heppel NH, Ashelford KE, Liddiard K, Hendrickson EA, Baird DM. Escape from telomere-driven crisis is DNA ligase III dependent. Cell Rep 2014; 8:1063-76. [PMID: 25127141 DOI: 10.1016/j.celrep.2014.07.007] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Revised: 05/28/2014] [Accepted: 07/10/2014] [Indexed: 12/27/2022] Open
Abstract
Short dysfunctional telomeres are capable of fusion, generating dicentric chromosomes and initiating breakage-fusion-bridge cycles. Cells that escape the ensuing cellular crisis exhibit large-scale genomic rearrangements that drive clonal evolution and malignant progression. We demonstrate that there is an absolute requirement for fully functional DNA ligase III (LIG3), but not ligase IV (LIG4), to facilitate the escape from a telomere-driven crisis. LIG3- and LIG4-dependent alternative (A) and classical (C) nonhomologous end-joining (NHEJ) pathways were capable of mediating the fusion of short dysfunctional telomeres, both displaying characteristic patterns of microhomology and deletion. Cells that failed to escape crisis exhibited increased proportions of C-NHEJ-mediated interchromosomal fusions, whereas those that escaped displayed increased proportions of intrachromosomal fusions. We propose that the balance between inter- and intrachromosomal telomere fusions dictates the ability of human cells to escape crisis and is influenced by the relative activities of A- and C-NHEJ at short dysfunctional telomeres.
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Affiliation(s)
- Rhiannon E Jones
- Institute of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | - Sehyun Oh
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, MN 55455, USA
| | - Julia W Grimstead
- Institute of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | - Jacob Zimbric
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, MN 55455, USA
| | - Laureline Roger
- Institute of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | - Nicole H Heppel
- Institute of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | - Kevin E Ashelford
- Institute of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | - Kate Liddiard
- Institute of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | - Eric A Hendrickson
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, MN 55455, USA
| | - Duncan M Baird
- Institute of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK.
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228
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Paini M, Crippa S, Partelli S, Scopelliti F, Tamburrino D, Baldoni A, Falconi M. Molecular pathology of intraductal papillary mucinous neoplasms of the pancreas. World J Gastroenterol 2014; 20:10008-10023. [PMID: 25110429 PMCID: PMC4123331 DOI: 10.3748/wjg.v20.i29.10008] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Accepted: 04/09/2014] [Indexed: 02/06/2023] Open
Abstract
Since the first description of intraductal papillary mucinous neoplasms (IPMNs) of the pancreas in the eighties, their identification has dramatically increased in the last decades, hand to hand with the improvements in diagnostic imaging and sampling techniques for the study of pancreatic diseases. However, the heterogeneity of IPMNs and their malignant potential make difficult the management of these lesions. The objective of this review is to identify the molecular characteristics of IPMNs in order to recognize potential markers for the discrimination of more aggressive IPMNs requiring surgical resection from benign IPMNs that could be observed. We briefly summarize recent research findings on the genetics and epigenetics of intraductal papillary mucinous neoplasms, identifying some genes, molecular mechanisms and cellular signaling pathways correlated to the pathogenesis of IPMNs and their progression to malignancy. The knowledge of molecular biology of IPMNs has impressively developed over the last few years. A great amount of genes functioning as oncogenes or tumor suppressor genes have been identified, in pancreatic juice or in blood or in the samples from the pancreatic resections, but further researches are required to use these informations for clinical intent, in order to better define the natural history of these diseases and to improve their management.
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MESH Headings
- Biomarkers, Tumor/genetics
- Biomarkers, Tumor/metabolism
- Carcinoma, Pancreatic Ductal/classification
- Carcinoma, Pancreatic Ductal/genetics
- Carcinoma, Pancreatic Ductal/metabolism
- Carcinoma, Pancreatic Ductal/pathology
- Carcinoma, Papillary/classification
- Carcinoma, Papillary/genetics
- Carcinoma, Papillary/metabolism
- Carcinoma, Papillary/pathology
- DNA Methylation
- Epigenesis, Genetic
- Gene Expression Regulation, Neoplastic
- Genetic Predisposition to Disease
- Genetic Testing
- Humans
- Neoplasms, Cystic, Mucinous, and Serous/classification
- Neoplasms, Cystic, Mucinous, and Serous/genetics
- Neoplasms, Cystic, Mucinous, and Serous/metabolism
- Neoplasms, Cystic, Mucinous, and Serous/pathology
- Pancreatic Neoplasms/classification
- Pancreatic Neoplasms/genetics
- Pancreatic Neoplasms/metabolism
- Pancreatic Neoplasms/pathology
- Phenotype
- Predictive Value of Tests
- Signal Transduction
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229
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Gobbini E, Trovesi C, Cassani C, Longhese MP. Telomere uncapping at the crossroad between cell cycle arrest and carcinogenesis. Mol Cell Oncol 2014; 1:e29901. [PMID: 27308311 PMCID: PMC4905175 DOI: 10.4161/mco.29901] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Revised: 06/24/2014] [Accepted: 06/30/2014] [Indexed: 01/24/2023]
Abstract
Telomeres are nucleoprotein complexes that protect the natural ends of chromosomes from fusion and degradation and prevent them eliciting a checkpoint response. This protective function, which is called telomere capping, is largely mediated by telomere-binding proteins that suppress checkpoint activation and DNA repair activities. Telomere dysfunction through progressive shortening or removal of capping proteins leads to a checkpoint-mediated block of cell proliferation, which acts as a cancer-suppressor mechanism. However, genetic alterations that inactivate the checkpoint can lead to further telomere erosion and increased genomic instability that, coupled with the activation of mechanisms to restabilize telomeres, can drive the oncogenic process.
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Affiliation(s)
- Elisa Gobbini
- Dipartimento di Biotecnologie e Bioscienze; Università degli Studi di Milano-Bicocca; Milano, Italia
| | - Camilla Trovesi
- Dipartimento di Biotecnologie e Bioscienze; Università degli Studi di Milano-Bicocca; Milano, Italia
| | - Corinne Cassani
- Dipartimento di Biotecnologie e Bioscienze; Università degli Studi di Milano-Bicocca; Milano, Italia
| | - Maria Pia Longhese
- Dipartimento di Biotecnologie e Bioscienze; Università degli Studi di Milano-Bicocca; Milano, Italia
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230
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Samassekou O, Bastien N, Lichtensztejn D, Yan J, Mai S, Drouin R. DifferentTP53mutations are associated with specific chromosomal rearrangements, telomere length changes, and remodeling of the nuclear architecture of telomeres. Genes Chromosomes Cancer 2014; 53:934-50. [DOI: 10.1002/gcc.22205] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Accepted: 07/02/2014] [Indexed: 02/06/2023] Open
Affiliation(s)
- Oumar Samassekou
- Division of Genetics; Department of Pediatrics; Faculty of Medicine and Health Sciences; Université de Sherbrooke; Sherbrooke QC Canada
- Manitoba Institute of Cell Biology; CancerCare Manitoba; Department of Physiology; Faculty of Medicine, University of Manitoba; Winnipeg MB Canada
| | - Nathalie Bastien
- Division of Genetics; Department of Pediatrics; Faculty of Medicine and Health Sciences; Université de Sherbrooke; Sherbrooke QC Canada
| | - Daniel Lichtensztejn
- Manitoba Institute of Cell Biology; CancerCare Manitoba; Department of Physiology; Faculty of Medicine, University of Manitoba; Winnipeg MB Canada
| | - Ju Yan
- Division of Genetics; Department of Pediatrics; Faculty of Medicine and Health Sciences; Université de Sherbrooke; Sherbrooke QC Canada
| | - Sabine Mai
- Manitoba Institute of Cell Biology; CancerCare Manitoba; Department of Physiology; Faculty of Medicine, University of Manitoba; Winnipeg MB Canada
| | - Régen Drouin
- Division of Genetics; Department of Pediatrics; Faculty of Medicine and Health Sciences; Université de Sherbrooke; Sherbrooke QC Canada
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231
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Lin TT, Norris K, Heppel NH, Pratt G, Allan JM, Allsup DJ, Bailey J, Cawkwell L, Hills R, Grimstead JW, Jones RE, Britt-Compton B, Fegan C, Baird DM, Pepper C. Telomere dysfunction accurately predicts clinical outcome in chronic lymphocytic leukaemia, even in patients with early stage disease. Br J Haematol 2014; 167:214-23. [PMID: 24990087 DOI: 10.1111/bjh.13023] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Accepted: 06/03/2014] [Indexed: 12/18/2022]
Abstract
Defining the prognosis of individual cancer sufferers remains a significant clinical challenge. Here we assessed the ability of high-resolution single telomere length analysis (STELA), combined with an experimentally derived definition of telomere dysfunction, to predict the clinical outcome of patients with chronic lymphocytic leukaemia (CLL). We defined the upper telomere length threshold at which telomere fusions occur and then used the mean of the telomere 'fusogenic' range as a prognostic tool. Patients with telomeres within the fusogenic range had a significantly shorter overall survival (P < 0·0001; Hazard ratio [HR] = 13·2, 95% confidence interval [CI] = 11·6-106·4) and this was preserved in early-stage disease patients (P < 0·0001, HR=19·3, 95% CI = 17·8-802·5). Indeed, our assay allowed the accurate stratification of Binet stage A patients into those with indolent disease (91% survival at 10 years) and those with poor prognosis (13% survival at 10 years). Furthermore, patients with telomeres above the fusogenic mean showed superior prognosis regardless of their IGHV mutation status or cytogenetic risk group. In keeping with this finding, telomere dysfunction was the dominant variable in multivariate analysis. Taken together, this study provides compelling evidence for the use of high-resolution telomere length analysis coupled with a definition of telomere dysfunction in the prognostic assessment of CLL.
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Affiliation(s)
- Thet Thet Lin
- Cardiff CLL Research Group, Institute of Cancer & Genetics, School of Medicine, Cardiff University, Cardiff, UK
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232
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Abstract
Chromosome translocations are catastrophic genomic events and often play key roles in tumorigenesis. Yet the biogenesis of chromosome translocations is remarkably poorly understood. Recent work has delineated several distinct mechanistic steps in the formation of translocations, and it has become apparent that non-random spatial genome organization, DNA repair pathways and chromatin features, including histone marks and the dynamic motion of broken chromatin, are critical for determining translocation frequency and partner selection.
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Affiliation(s)
| | - Tom Misteli
- National Cancer Institute, Bethesda, Maryland 20892, USA
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233
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Bartocci C, Diedrich JK, Ouzounov I, Li J, Piunti A, Pasini D, Yates JR, Lazzerini Denchi E. Isolation of chromatin from dysfunctional telomeres reveals an important role for Ring1b in NHEJ-mediated chromosome fusions. Cell Rep 2014; 7:1320-32. [PMID: 24813883 DOI: 10.1016/j.celrep.2014.04.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Revised: 03/04/2014] [Accepted: 04/02/2014] [Indexed: 12/30/2022] Open
Abstract
When telomeres become critically short, DNA damage response factors are recruited at chromosome ends, initiating a cellular response to DNA damage. We performed proteomic isolation of chromatin fragments (PICh) in order to define changes in chromatin composition that occur upon onset of acute telomere dysfunction triggered by depletion of the telomere-associated factor TRF2. This unbiased purification of telomere-associated proteins in functional or dysfunctional conditions revealed the dynamic changes in chromatin composition that take place at telomeres upon DNA damage induction. On the basis of our results, we describe a critical role for the polycomb group protein Ring1b in nonhomologous end-joining (NHEJ)-mediated end-to-end chromosome fusions. We show that cells with reduced levels of Ring1b have a reduced ability to repair uncapped telomeric chromatin. Our data represent an unbiased isolation of chromatin undergoing DNA damage and are a valuable resource to map the changes in chromatin composition in response to DNA damage activation.
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Affiliation(s)
- Cristina Bartocci
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Jolene K Diedrich
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Iliana Ouzounov
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Julia Li
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Andrea Piunti
- Department of Experimental Oncology, European Institute of Oncology, 20146 Milan, Italy
| | - Diego Pasini
- Department of Experimental Oncology, European Institute of Oncology, 20146 Milan, Italy
| | - John R Yates
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Eros Lazzerini Denchi
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA.
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234
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Abstract
Telomeres are ribonucleoprotein structures capping the end of every linear chromosome. In all vertebrates, they are composed of TTAGGG repeats coated with specific protecting proteins. Telomeres shorten with each mitotic cell division, but telomerase, a reverse transcriptase, elongate telomeres in very specific cells, such as embryonic and adult stem cells. Although telomere sequence is identical in mice and humans and telomeres serve the same role of protecting chromosomes and genetic information from damage and erosion in both species, abnormalities in telomere maintenance and in telomerase function do not coincide in phenotype in humans and mice. The telomeres of most laboratory mice are 5 to 10 times longer than in humans, but their lifespan is 30 times shorter. Complete absence of telomerase has little expression in phenotype over several generations in mice, whereas heterozygosity for telomerase mutations in humans is sufficient to result in organ regeneration defect and cancer development. Patients with telomerase deficiency and very short telomeres may develop aplastic anemia, pulmonary fibrosis, or cirrhosis, whereas telomerase-null murine models display only modest hematopoietic deficiency and develop emphysema when exposed to cigarette smoke. In summary, telomerase deficiency in both humans and mice accelerate telomere shortening, but its consequences in the different organs and in the organism diverge, mainly due to telomere length differences.
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235
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Saeed H, Iqtedar M. Stem cell function and maintenance - ends that matter: role of telomeres and telomerase. J Biosci 2014; 38:641-9. [PMID: 23938394 DOI: 10.1007/s12038-013-9346-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Stem cell research holds a promise to treat and prevent age-related degenerative changes in humans. Literature is replete with studies showing that stem cell function declines with aging, especially in highly proliferative tissues/ organs. Among others, telomerase and telomere damage is one of the intrinsic physical instigators that drive agerelated degenerative changes. In this review we provide brief overview of telomerase-deficient aging affects in diverse stem cells populations. Furthermore, potential disease phenotypes associated with telomerase dysregulation in a specific stem cell population is also discussed in this review. Additionally, the role of telomerase in stem cell driven cancer is also briefly touched upon.
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Affiliation(s)
- Hamid Saeed
- Department of Endocrinology, School of Medicine, Stanford University, Stanford, CA, USA.
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236
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Sherr CJ. Ink4-Arf locus in cancer and aging. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2014; 1:731-41. [PMID: 22960768 PMCID: PMC3434949 DOI: 10.1002/wdev.40] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Three tumor suppressor genes at the small (<50 kb) INK4-ARF (CDKN2A/B) locus on human chromosome 9p21 coordinate a signaling network that depends on the activities of the retinoblastoma (RB) protein and the p53 transcription factor. Disruption of this circuitry, frequently by codeletion of INK4-ARF, is a hallmark of cancer, begging the question of why the intimate genetic linkage of these tumor suppressor genes has been maintained in mammals despite the risk of their coinactivation. The INK4-ARF locus is not highly expressed under normal physiologic conditions in young mammals, but its induction becomes more pronounced as animals age. Notably, INK4-ARF is actively silenced en bloc in embryonic, fetal, and adult stem cells but becomes poised to respond to oncogenic stress signals as stem cells lose their self-renewal capacity and differentiate, thereby providing a potent barrier to tumor formation. Epigenetic remodeling of the locus as a whole provides a mechanism for coordinating the activities of RB and p53. A hypothesis is that the INK4-ARF locus may have evolved to physiologically restrict the self-renewal capacities and numbers of stem and progenitor cells with the attendant consequence of limiting tissue regenerative capacity, particularly as animals age. Deletion of INK4-ARF contributes to the aberrant self-renewal capacity of tumor cells and occurs frequently in many forms of human cancer.
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Affiliation(s)
- Charles J Sherr
- Howard Hughes Medical Institute, Department of Tumor Cell Biology, St. Jude Children's Research Hospital, Memphis, TN, USA.
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237
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Telomere length in peripheral blood leukocytes is associated with risk of colorectal cancer in Chinese population. PLoS One 2014; 9:e88135. [PMID: 24498432 PMCID: PMC3912164 DOI: 10.1371/journal.pone.0088135] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Accepted: 01/05/2014] [Indexed: 02/07/2023] Open
Abstract
Background Human telomeres, tandem repeats of TTAGGG nucleotides at the ends of chromosomes, are essential for maintaining genomic integrity and stability. Results of previous epidemiologic studies about the association of telomere length with risk of colorectal cancer (CRC) have been conflicting. Methods A case-control study was conducted in a Han population in Wuhan, central China. The relative telomere length (RTL) was measured in peripheral blood leukocytes (PBLs) using quantitative real-time polymerase chain reaction (PCR) in 628 CRC cases and 1,256 age and sex frequency matched cancer-free controls. Odds ratios (OR) and 95% confidence intervals (95% CI) were calculated using unconditional logistic regression models to evaluate the association between RTL and CRC risk. Results Using median RTL in the controls as the cutoff, individuals with shorter RTL were associated with a significantly increased risk of CRC (adjusted OR = 1.27, 95%CI: 1.05–1.55). When participants were further categorized into 3 and 4 groups according to the tertile and quartile RTL values of controls, significant relationships were still observed between shorter RTL and increased CRC risk (OR per tertile = 1.13, 95%CI: 1.00–1.28, Ptrend = 0.045; OR per quartile = 1.12, 95%CI: 1.03–1.23, Ptrend = 0.012). In stratified analyses, significant association between shorter RTL and increased CRC risk was found in females, individuals younger than 60 years old, never smokers and never drinkers. Conclusions This study suggested that short telomere length in PBLs was significantly associated with an increased risk of CRC in Chinese Han population. Further validation in large prospective studies and investigation of the biologic mechanisms are warranted.
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238
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Marrone A, Dokal I. Dyskeratosis congenita: a disorder of telomerase deficiency and its relationship to other diseases. ACTA ACUST UNITED AC 2014. [DOI: 10.1586/17469872.1.3.463] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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239
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Ning B, Su Z, Mei N, Hong H, Deng H, Shi L, Fuscoe JC, Tolleson WH. Toxicogenomics and cancer susceptibility: advances with next-generation sequencing. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART C, ENVIRONMENTAL CARCINOGENESIS & ECOTOXICOLOGY REVIEWS 2014; 32:121-58. [PMID: 24875441 PMCID: PMC5712441 DOI: 10.1080/10590501.2014.907460] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The aim of this review is to comprehensively summarize the recent achievements in the field of toxicogenomics and cancer research regarding genetic-environmental interactions in carcinogenesis and detection of genetic aberrations in cancer genomes by next-generation sequencing technology. Cancer is primarily a genetic disease in which genetic factors and environmental stimuli interact to cause genetic and epigenetic aberrations in human cells. Mutations in the germline act as either high-penetrance alleles that strongly increase the risk of cancer development, or as low-penetrance alleles that mildly change an individual's susceptibility to cancer. Somatic mutations, resulting from either DNA damage induced by exposure to environmental mutagens or from spontaneous errors in DNA replication or repair are involved in the development or progression of the cancer. Induced or spontaneous changes in the epigenome may also drive carcinogenesis. Advances in next-generation sequencing technology provide us opportunities to accurately, economically, and rapidly identify genetic variants, somatic mutations, gene expression profiles, and epigenetic alterations with single-base resolution. Whole genome sequencing, whole exome sequencing, and RNA sequencing of paired cancer and adjacent normal tissue present a comprehensive picture of the cancer genome. These new findings should benefit public health by providing insights in understanding cancer biology, and in improving cancer diagnosis and therapy.
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Affiliation(s)
- Baitang Ning
- National Center for Toxicological Research, Food and Drug Administration, Jefferson, Arkansas, USA
| | - Zhenqiang Su
- National Center for Toxicological Research, Food and Drug Administration, Jefferson, Arkansas, USA
| | - Nan Mei
- National Center for Toxicological Research, Food and Drug Administration, Jefferson, Arkansas, USA
| | - Huixiao Hong
- National Center for Toxicological Research, Food and Drug Administration, Jefferson, Arkansas, USA
| | - Helen Deng
- Arkansas Department of Health and Human Service, Little Rock, Arkansas, USA
| | - Leming Shi
- National Center for Toxicological Research, Food and Drug Administration, Jefferson, Arkansas, USA
- Center for Pharmacogenomics, School of Pharmacy, Fudan University, Pudong District, Shanghai, China
| | - James C. Fuscoe
- National Center for Toxicological Research, Food and Drug Administration, Jefferson, Arkansas, USA
| | - William H. Tolleson
- National Center for Toxicological Research, Food and Drug Administration, Jefferson, Arkansas, USA
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240
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Abstract
Telomerase reverse transcriptase (TERT) is the protein component of telomerase and combined with an RNA molecule, telomerase RNA component, forms the telomerase enzyme responsible for telomere elongation. Telomerase is essential for maintaining telomere length from replicative attrition and thus contributes to the preservation of genome integrity. Although diverse mouse models have been developed and studied to prove the physiological roles of telomerase as a telomere- elongating enzyme, recent studies have revealed non-canonical TERT activities beyond telomeres. To gain insights into the physiological impact of extra-telomeric roles, this review revisits the strategies and phenotypes of telomerase mouse models in terms of the extra-telomeric functions of telomerase.
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Affiliation(s)
- Young Hoon Sung
- Department of Biochemistry, College of Life Science and Biotechnology, Laboratory Animal Research Center, Yonsei University, Seoul, Korea
| | - Muhammad Ali
- Department of Biochemistry, College of Life Science and Biotechnology, Laboratory Animal Research Center, Yonsei University, Seoul, Korea
| | - Han-Woong Lee
- Department of Biochemistry, College of Life Science and Biotechnology, Laboratory Animal Research Center, Yonsei University, Seoul, Korea
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241
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Wang S, Chen Y, Qu F, He S, Huang X, Jiang H, Jin T, Wan S, Xing J. Association between leukocyte telomere length and glioma risk: a case-control study. Neuro Oncol 2013; 16:505-12. [PMID: 24366909 DOI: 10.1093/neuonc/not240] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Compelling epidemiological evidence indicates that alterations of telomere length are associated with risks of many malignancies in a tumor-specific manner, such as lung cancer, breast cancer, and non-Hodgkin's lymphoma. However, the association between leukocyte telomere length and glioma risk has not been investigated. METHODS Relative telomere length (RTL) of peripheral blood leukocytes from 467 glioma patients and 467 healthy controls, matched by age and sex, was measured using the real-time PCR-based method in a case-control study. An unconditional multivariate logistic regression model was applied to estimate the association between RTL and glioma risk. RESULTS Glioma patients showed notably longer RTL than controls (median, 0.555 vs 0.444; P > .04). RTL was negatively correlated with age in both cases (ρ = -0.430; P < .001) and controls (ρ = -0.388; P < .001). After adjusting for age, sex, smoking status and family history of cancer, multivariate logistic regression analysis showed that there was a U-shaped association between RTL and glioma risk (P for nonlinearity <.001). Compared with individuals in the second tertile of RTL, the odds ratios (95% CI) for participants in the first and third tertiles were 2.16 (range, 1.52-3.09) and 3.51 (range, 2.45-5.00), respectively. Stratified analysis showed that the association between RTL and glioma risk was not modulated by major host characteristics. CONCLUSIONS Our study demonstrates for the first time that either shorter or longer RTL in peripheral blood leukocytes is associated with increased glioma risk, which warrants further investigation in the future.
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Affiliation(s)
- Shaolong Wang
- Department of Oncology, First Affiliated Hospital of Chengdu Medical College, Chengdu, China (S.W., H.J.); State Key Laboratory of Cancer Biology and Experimental Teaching Center of Basic Medicine, Xi'an, China (Y.C., F.Q., X.H., J.X.); Department of Neurosurgery, Tangdu Hospital, Fourth Military Medical University, Xi'an, China (S.H.); National Engineering Research Center for Miniaturized Detection Systems, School of Life Sciences, Northwest University, Xi'an, China (T.J.); Division of Population Science, Department of Medical Oncology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania (S.W.)
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242
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Pancreatic cancer. Mol Oncol 2013. [DOI: 10.1017/cbo9781139046947.049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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243
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Mason PJ, Perdigones N. Telomere biology and translational research. Transl Res 2013; 162:333-42. [PMID: 24070997 PMCID: PMC4021592 DOI: 10.1016/j.trsl.2013.08.009] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Accepted: 08/30/2013] [Indexed: 12/27/2022]
Affiliation(s)
- Philip J Mason
- Division of Hematology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA.
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244
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Zack TI, Schumacher SE, Carter SL, Cherniack AD, Saksena G, Tabak B, Lawrence MS, Zhsng CZ, Wala J, Mermel CH, Sougnez C, Gabriel SB, Hernandez B, Shen H, Laird PW, Getz G, Meyerson M, Beroukhim R. Pan-cancer patterns of somatic copy number alteration. Nat Genet 2013; 45:1134-40. [PMID: 24071852 PMCID: PMC3966983 DOI: 10.1038/ng.2760] [Citation(s) in RCA: 1307] [Impact Index Per Article: 118.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Determining how somatic copy number alterations (SCNAs) promote cancer is an important goal. We characterized SCNA patterns in 4,934 cancers from The Cancer Genome Atlas Pan-Cancer data set. Whole-genome doubling, observed in 37% of cancers, was associated with higher rates of every other type of SCNA, TP53 mutations, CCNE1 amplifications and alterations of the PPP2R complex. SCNAs that were internal to chromosomes tended to be shorter than telomere-bounded SCNAs, suggesting different mechanisms underlying their generation. Significantly recurrent focal SCNAs were observed in 140 regions, including 102 without known oncogene or tumor suppressor gene targets and 50 with significantly mutated genes. Amplified regions without known oncogenes were enriched for genes involved in epigenetic regulation. When levels of genomic disruption were accounted for, 7% of region pairs were anticorrelated, and these regions tended to encompass genes whose proteins physically interact, suggesting related functions. These results provide insights into mechanisms of generation and functional consequences of cancer-related SCNAs.
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Affiliation(s)
- Travis I Zack
- Broad Institute, Cambridge, Massachusetts, USA; Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA; Biophysics Program, Harvard University, Boston, Massachusetts, USA
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245
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Replication stress and mitotic dysfunction in cells expressing simian virus 40 large T antigen. J Virol 2013; 87:13179-92. [PMID: 24067972 DOI: 10.1128/jvi.02224-13] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We previously demonstrated that simian virus 40 (SV40) large T antigen (LT) binds to the Bub1 kinase, a key regulator of the spindle checkpoint and chromosome segregation. Bub1 mutations or altered expression patterns are linked to chromosome missegregation and are considered to be a driving force in some human cancers. Here we report that LT, dependent on Bub1 binding, causes micronuclei, lagging chromatin, and anaphase bridges, which are hallmarks of chromosomal instability (CIN) and Bub1 insufficiency. Using time-lapse microscopy, we demonstrate that LT imposes a Bub1 binding-dependent delay in the metaphase-to-anaphase transition. Kinetochore fibers reveal that LT, via Bub1 binding, causes aberrant kinetochore (KT)-microtubule (MT) attachments and a shortened interkinetochore distance, consistent with a lack of tension. Previously, we showed that LT also induces the DNA damage response (DDR) via Bub1 binding. Using inducible LT cell lines, we show that an activated DDR was observed before the appearance of anaphase bridges and micronuclei. Furthermore, LT induction in serum-starved cells demonstrated γ-H2AX accumulation in cells that had not yet entered mitosis. Thus, DDR activation can occur independently of chromosome segregation defects. Replication stress pathways may be responsible, because signatures of replication stress were observed, which were attenuated by exogenous supplementation with nucleosides. Our observations allow us to propose a model that explains and integrates the diverse manifestations of genomic instability induced by LT.
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246
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Wang Y, Sharpless N, Chang S. p16(INK4a) protects against dysfunctional telomere-induced ATR-dependent DNA damage responses. J Clin Invest 2013; 123:4489-501. [PMID: 24091330 DOI: 10.1172/jci69574] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Accepted: 07/24/2013] [Indexed: 11/17/2022] Open
Abstract
Dysfunctional telomeres limit cellular proliferative capacity by activating the p53-p21- and p16(INK4a)-Rb-dependent DNA damage responses (DDRs). The p16(INK4a) tumor suppressor accumulates in aging tissues, is a biomarker for cellular senescence, and limits stem cell function in vivo. While the activation of a p53-dependent DDR by dysfunctional telomeres has been well documented in human cells and mouse models, the role for p16(INK4a) in response to telomere dysfunction remains unclear. Here, we generated protection of telomeres 1b p16-/- mice (Pot1bΔ/Δ;p16-/-) to address the function of p16(INK4a) in the setting of telomere dysfunction in vivo. We found that deletion of p16(INK4a) accelerated organ impairment and observed functional defects in highly proliferative organs, including the hematopoietic system, small intestine, and testes. Pot1bΔ/Δ;p16-/- hematopoietic cells exhibited increased telomere loss, increased chromosomal fusions, and telomere replication defects. p16(INK4a) deletion enhanced the activation of the ATR-dependent DDR in Pot1bΔ/Δ hematopoietic cells, leading to p53 stabilization, increased p21-dependent cell cycle arrest, and elevated p53-dependent apoptosis. In contrast to p16(INK4a), deletion of p21 did not activate ATR, rescued proliferative defects in Pot1bΔ/Δ hematopoietic cells, and significantly increased organismal lifespan. Our results provide experimental evidence that p16(INK4a) exerts protective functions in proliferative cells bearing dysfunctional telomeres.
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247
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El Idrissi M, Hervieu V, Merle P, Mortreux F, Wattel E. Cause-specific telomere factors deregulation in hepatocellular carcinoma. JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2013; 32:64. [PMID: 24020493 PMCID: PMC3850108 DOI: 10.1186/1756-9966-32-64] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Accepted: 08/22/2013] [Indexed: 12/25/2022]
Abstract
Background Among the numerous genetic defects associated with hepatocarcinogenesis, telomere abnormalities appear to play a role both in tumor promotion and maintenance. Telomeres, the chromosome extremities, are protected by specific proteins, the shelterin complex and by additional factors. Besides telomerase dysregulation, expression changes of these telomere factors have been observed in cancers. Methods Here, we tested the hypothesis that such dysregulation might occur in hepatocellular carcinoma (HCC) with specific patterns depending on the cause of HCC. We compared telomere length, telomerase activity (TA), hTERT and telomere genes expression using PCR and Western-blot analyses between non-cirrhotic liver, peritumoral cirrhotic tissue (40 samples) and cancerous tissue (40 samples) derived from 40 patients with HBV-, HCV-, or alcohol-related HCC. Results Alterations in TA, hTERT expression and telomere length between non-cirrhotic, cirrhotic, and tumor samples were not significantly influenced by the cause of HCC. In contrast, the expression pattern of hTR, shelterin, and non-shelterin telomere protective factors clearly distinguished the 3 causes of cirrhosis and HCC. For patients with HBV diseased liver, when compared with non-cirrhotic liver, the cirrhotic tissue underexpressed all shelterin and all but HMRE11A and RAD50 non-shelterin telomere factors. For HCV the expression level of POT1, RAP1, Ku80, and RAD50 was higher in cirrhotic than in non-cirrhotic liver samples without evidence for significant transcriptional change for the remaining genes. For alcohol-related liver diseases, the expression level of POT1, RAP1, TIN2, hMRE11A, hMRE11B, Ku70, Ku80, RAD50, TANK1, and PINX1 was higher in cirrhotic than in non-cirrhotic liver samples. For the 3 causes of HCC, there was no significant change in shelterin and non-shelterin gene expression between cirrhosis and HCC samples. Conclusions These results validate our hypotheses and demonstrate that cirrhosis and HCC add-up numerous telomere dysfunctions including numerous cause-specific changes that appear to occur early during the course of the disease.
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Affiliation(s)
- Manale El Idrissi
- UMR5239 Oncovirologie et Biothérapies, Faculté de Médecine Lyon Sud, ENS - HCL, Université Lyon 1, CNRS, Pierre Bénite, France.
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248
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Herter-Sprie GS, Kung AL, Wong KK. New cast for a new era: preclinical cancer drug development revisited. J Clin Invest 2013; 123:3639-45. [PMID: 23999436 DOI: 10.1172/jci68340] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Molecularly targeted agents promise to revolutionize therapeutics by reducing morbidity and mortality in patients with cancer. However, despite an urgent need for more effective anticancer compounds, current preclinical drug evaluations largely fail to satisfy the demand. New preclinical strategies, including the improvement of sophisticated mouse models and co-clinical study designs, are being used to augment the predictive value of animal-based translational cancer research. Here, we review the development of successful preclinical antineoplastic agents, their associated limitations, and alternative methods to predict clinical outcomes.
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249
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Zhou J, Richardson M, Reddy V, Menon M, Barrack ER, Reddy GPV, Kim SH. Structural and functional association of androgen receptor with telomeres in prostate cancer cells. Aging (Albany NY) 2013; 5:3-17. [PMID: 23363843 PMCID: PMC3616228 DOI: 10.18632/aging.100524] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Telomeres protect the ends of linear chromosomes from being recognized as damaged DNA, and telomere stability is required for genome stability. Here we demonstrate that telomere stability in androgen receptor (AR)-positive LNCaP human prostate cancer cells is dependent on AR and androgen, as AR inactivation by AR antagonist bicalutamide (Casodex), AR-knockdown, or androgen-depletion caused telomere dysfunction, and the effect of androgen-depletion or Casodex was blocked by the addition of androgen. Notably, neither actinomycin D nor cycloheximide blocked the DNA damage response to Casodex, indicating that the role of AR in telomere stability is independent of its role in transcription. We also demonstrate that AR is a component of telomeres, as AR-bound chromatin contains telomeric DNA, and telomeric chromatin contains AR. Importantly, AR inactivation by Casodex caused telomere aberrations, including multiple abnormal telomere signals, remindful of a fragile telomere phenotype that has been described previously to result from defective telomere DNA replication. We suggest that AR plays an important role in telomere stability and replication of telomere DNA in prostate cancer cells, and that AR inactivation-mediated telomere dysfunction may contribute to genomic instability and progression of prostate cancer cells.
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Affiliation(s)
- Junying Zhou
- Vattikuti Urology Institute, Henry Ford Hospital, Detroit, MI 48202, USA
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Roger L, Jones RE, Heppel NH, Williams GT, Sampson JR, Baird DM. Extensive telomere erosion in the initiation of colorectal adenomas and its association with chromosomal instability. J Natl Cancer Inst 2013; 105:1202-11. [PMID: 23918447 DOI: 10.1093/jnci/djt191] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Telomere shortening, dysfunction, and fusion may facilitate the acquisition of large-scale genomic rearrangements, driving clonal evolution and tumor progression. The relative contribution that telomere dysfunction and/or APC mutation play in the chromosome instability that occurs during colorectal tumorigenesis is not clear. METHODS We used high-resolution telomere length and fusion analysis to analyze 85 adenomatous colorectal polyps obtained from 10 patients with familial adenomatous polyposis and a panel of 50 colorectal carcinomas with patient-matched normal colonic mucosa. Telomerase activity was determined using the telomeric repeat amplification protocol. Array-CGH was used to detect large-scale genomic rearrangements. Pearson correlation and Student t test were used, and all statistical tests were two-sided. RESULTS Despite the presence of telomerase activity, we observed apparent telomere shortening in colorectal polyps that correlated with large-scale genomic rearrangements (P < .0001) but was independent of polyp size and indistinguishable from that observed in colorectal carcinomas (P = .82). We also observed apparent lengthening of telomeres in both polyps and carcinomas. The extensive differences in mean telomere length of up to 4.6kb between patient-matched normal mucosa and polyps were too large to be accounted for by replicative telomere erosion alone. Telomere fusion events were detected in both polyps and carcinomas; the mutational spectrum accompanying fusion was consistent with alternative nonhomologous end joining. CONCLUSIONS Telomere length distributions observed in colorectal polyps reflect the telomere length composition of the normal originating cells from which clonal growth was initiated. Originating cells containing both short telomeres and APC mutations may give rise to polyps that exhibit short telomeres and are prone to telomere dysfunction, driving genomic instability and progression to malignancy. J Natl Cancer Inst;2013;105:1202-1211.
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Affiliation(s)
- Laureline Roger
- Institute of Cancer and Genetics, School of Medicine, Cardiff University, Cardiff, UK
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