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Bailey SM, Kunkel SR, Bedford JS, Cornforth MN. The Central Role of Cytogenetics in Radiation Biology. Radiat Res 2024; 202:227-259. [PMID: 38981612 DOI: 10.1667/rade-24-00038.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Accepted: 04/23/2024] [Indexed: 07/11/2024]
Abstract
Radiation cytogenetics has a rich history seldom appreciated by those outside the field. Early radiobiology was dominated by physics and biophysical concepts that borrowed heavily from the study of radiation-induced chromosome aberrations. From such studies, quantitative relationships between biological effect and changes in absorbed dose, dose rate and ionization density were codified into key concepts of radiobiological theory that have persisted for nearly a century. This review aims to provide a historical perspective of some of these concepts, including evidence supporting the contention that chromosome aberrations underlie development of many, if not most, of the biological effects of concern for humans exposed to ionizing radiations including cancer induction, on the one hand, and tumor eradication on the other. The significance of discoveries originating from these studies has widened and extended far beyond their original scope. Chromosome structural rearrangements viewed in mitotic cells were first attributed to the production of breaks by the radiations during interphase, followed by the rejoining or mis-rejoining among ends of other nearby breaks. These relatively modest beginnings eventually led to the discovery and characterization of DNA repair of double-strand breaks by non-homologous end joining, whose importance to various biological processes is now widely appreciated. Two examples, among many, are V(D)J recombination and speciation. Rapid technological advancements in cytogenetics, the burgeoning fields of molecular radiobiology and third-generation sequencing served as a point of confluence between the old and new. As a result, the emergent field of "cytogenomics" now becomes uniquely positioned for the purpose of more fully understanding mechanisms underlying the biological effects of ionizing radiation exposure.
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Affiliation(s)
- Susan M Bailey
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado
| | - Stephen R Kunkel
- Department of Radiation Oncology, University of Texas Medical Branch, Galveston, Texas
| | - Joel S Bedford
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado
| | - Michael N Cornforth
- Department of Radiation Oncology, University of Texas Medical Branch, Galveston, Texas
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2
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Bolzán AD. Considerations on the scoring of telomere aberrations in vertebrate cells detected by telomere or telomere plus centromere PNA-FISH. MUTATION RESEARCH. REVIEWS IN MUTATION RESEARCH 2024; 794:108507. [PMID: 38802042 DOI: 10.1016/j.mrrev.2024.108507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 05/20/2024] [Accepted: 05/21/2024] [Indexed: 05/29/2024]
Abstract
Given that telomeres play a fundamental role in maintaining genomic stability, the study of the chromosomal aberrations involving telomeric sequences is a topic of considerable research interest. In recent years, the scoring of these types of aberrations has been used in vertebrate cells, particularly human cells, to evaluate the effects of genotoxic agents on telomeres and the involvement of telomeric sequences on chromosomal aberrations. Currently, chromosomal aberrations involving telomeric sequences are evaluated in peripheral blood lymphocytes or immortalized cell lines, using telomere or telomere plus centromere fluorescence in situ hybridization (FISH) with Peptide Nucleic Acid (PNA) probes (PNA-FISH). The telomere PNA probe is more efficient in the detection of telomeric sequences than conventional FISH with a telomere DNA probe. In addition, the intensity of the telomeric PNA-FISH probe signal is directly correlated with the number of telomeric repeats. Therefore, use of this type of probe can identify chromosomal aberrations involving telomeres as well as determine the telomere length of the sample. There are several mistakes and inconsistencies in the literature regarding the identification of telomere aberrations, which prevent accurate scoring and data comparison between different publications concerning these types of aberrations. The aim of this review is to clarify these issues, and provide proper terminology and criteria for the identification, scoring, and analysis of telomere aberrations.
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Affiliation(s)
- Alejandro D Bolzán
- Laboratorio de Citogenética y Mutagénesis, Instituto Multidisciplinario de Biología Celular (IMBICE, CONICET-UNLP-CICPBA), calle 526 y Camino General Belgrano, La Plata, Buenos Aires B1906APO, Argentina; Universidad Nacional de La Plata, Facultad de Ciencias Naturales y Museo, calle 60 y 122, La Plata, Buenos Aires, Argentina.
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3
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Castellanos G, Valbuena DS, Pérez E, Villegas VE, Rondón-Lagos M. Chromosomal Instability as Enabling Feature and Central Hallmark of Breast Cancer. BREAST CANCER (DOVE MEDICAL PRESS) 2023; 15:189-211. [PMID: 36923397 PMCID: PMC10010144 DOI: 10.2147/bctt.s383759] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Accepted: 10/11/2022] [Indexed: 03/11/2023]
Abstract
Chromosomal instability (CIN) has become a topic of great interest in recent years, not only for its implications in cancer diagnosis and prognosis but also for its role as an enabling feature and central hallmark of cancer. CIN describes cell-to-cell variation in the number or structure of chromosomes in a tumor population. Although extensive research in recent decades has identified some associations between CIN with response to therapy, specific associations with other hallmarks of cancer have not been fully evidenced. Such associations place CIN as an enabling feature of the other hallmarks of cancer and highlight the importance of deepening its knowledge to improve the outcome in cancer. In addition, studies conducted to date have shown paradoxical findings about the implications of CIN for therapeutic response, with some studies showing associations between high CIN and better therapeutic response, and others showing the opposite: associations between high CIN and therapeutic resistance. This evidences the complex relationships between CIN with the prognosis and response to treatment in cancer. Considering the above, this review focuses on recent studies on the role of CIN in cancer, the cellular mechanisms leading to CIN, its relationship with other hallmarks of cancer, and the emerging therapeutic approaches that are being developed to target such instability, with a primary focus on breast cancer. Further understanding of the complexity of CIN and its association with other hallmarks of cancer could provide a better understanding of the cellular and molecular mechanisms involved in prognosis and response to treatment in cancer and potentially lead to new drug targets.
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Affiliation(s)
- Giovanny Castellanos
- Maestría en Ciencias Biológicas, Universidad Pedagógica y Tecnológica de Colombia, Tunja, Colombia.,School of Biological Sciences, Universidad Pedagógica y Tecnológica de Colombia, Tunja, Colombia
| | - Duván Sebastián Valbuena
- School of Biological Sciences, Universidad Pedagógica y Tecnológica de Colombia, Tunja, Colombia
| | - Erika Pérez
- School of Biological Sciences, Universidad Pedagógica y Tecnológica de Colombia, Tunja, Colombia
| | - Victoria E Villegas
- Centro de Investigaciones en Microbiología y Biotecnología-UR (CIMBIUR), Facultad de Ciencias Naturales, Universidad del Rosario, Bogotá, Colombia
| | - Milena Rondón-Lagos
- School of Biological Sciences, Universidad Pedagógica y Tecnológica de Colombia, Tunja, Colombia
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4
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Gozaly-Chianea Y, Roberts T, Slijepcevic P. The role of BRCA2 in the fragility of interstitial telomeric sites. MUTATION RESEARCH. GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2022; 878:503476. [PMID: 35649669 DOI: 10.1016/j.mrgentox.2022.503476] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 02/18/2022] [Accepted: 02/22/2022] [Indexed: 06/15/2023]
Abstract
We examined frequencies of radiation-induced chromosomal aberrations, using classical cytological methods, and DNA damage in interphase and metaphase cells, using a combination of FISH, CO-FISH, TIF (telomere dysfunction induced assay) and simultaneous detection of DNA damage and telomeric sequences in metaphase chromosomes, in Chinese hamster cells defective in BRCA2 and control cells. Given that the Chinese hamster genome contains large blocks of interstitial telomeric sites, our results allow us to examine the role of BRCA2 in the potential fragility of these sites, but also whether BRCA2 affects DNA repair within terminal telomeric sequences. BRCA2 defective cells exhibited greater frequencies of DNA damage within interstitial telomeric sites, as well as within terminal telomeric sites, relative to control cells. Therefore, BRCA2 deficiency contributes to the telomere dysfunction phenotype in Chinese hamster cells.
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Affiliation(s)
- Yaghoub Gozaly-Chianea
- Department of Life Sciences, College of Health, Medicine and Life Sciences, Brunel University London, Kingston Lane, Uxbridge UB8 3PH, UK
| | - Terry Roberts
- Department of Life Sciences, College of Health, Medicine and Life Sciences, Brunel University London, Kingston Lane, Uxbridge UB8 3PH, UK
| | - Predrag Slijepcevic
- Department of Life Sciences, College of Health, Medicine and Life Sciences, Brunel University London, Kingston Lane, Uxbridge UB8 3PH, UK.
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5
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Cornforth MN, Bedford JS, Bailey SM. Destabilizing Effects of Ionizing Radiation on Chromosomes: Sizing up the Damage. Cytogenet Genome Res 2021; 161:328-351. [PMID: 34488218 DOI: 10.1159/000516523] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 02/16/2021] [Indexed: 11/19/2022] Open
Abstract
For long-term survival and evolution, all organisms have depended on a delicate balance between processes involved in maintaining stability of their genomes and opposing processes that lead toward destabilization. At the level of mammalian somatic cells in renewal tissues, events or conditions that can tip this balance toward instability have attracted special interest in connection with carcinogenesis. Mutations affecting DNA (and its subsequent repair) would, of course, be a major consideration here. These may occur spontaneously through endogenous cellular processes or as a result of exposure to mutagenic environmental agents. It is in this context that we discuss the rather unique destabilizing effects of ionizing radiation (IR) in terms of its ability to cause large-scale structural rearrangements to the genome. We present arguments supporting the conclusion that these and other important effects of IR originate largely from microscopically visible chromosome aberrations.
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Affiliation(s)
- Michael N Cornforth
- Department of Radiation Oncology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Joel S Bedford
- Department of Environmental & Radiological Health Sciences, Colorado State University, Fort Collins, Colorado, USA
| | - Susan M Bailey
- Department of Environmental & Radiological Health Sciences, Colorado State University, Fort Collins, Colorado, USA
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6
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Bolzán AD. Mutagen-induced telomere instability in human cells. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2021; 868-869:503387. [PMID: 34454696 DOI: 10.1016/j.mrgentox.2021.503387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 07/13/2021] [Accepted: 07/18/2021] [Indexed: 11/27/2022]
Abstract
Telomere instability is one of the main sources of genome instability and may result from chromosome end loss (due to chromosome breakage at one or both ends) or, more frequently, telomere dysfunction. Dysfunctional telomeres arise when they lose their end-capping function or become critically short, which causes chromosomal termini to behave like a DNA double-strand break. Telomere instability may occur at the chromosomal or at the molecular level, giving rise, respectively, to telomere-related chromosomal aberrations or the loss or modification of any of the components of the telomere (telomere DNA, telomere-associated proteins, or telomere RNA). Since telomeres play a fundamental role in maintaining genome stability, the study of telomere instability in cells exposed to mutagens is of great importance to understand the telomere-driven genomic instability present in those cells. In the present review, we will focus on the current knowledge about telomere instability induced by physical, chemical, and biological mutagens in human cells.
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Affiliation(s)
- Alejandro D Bolzán
- Laboratorio de Citogenética y Mutagénesis, Instituto Multidisciplinario de Biología Celular (IMBICE, CONICET-CICPBA-UNLP), calle 526 y Camino General Belgrano, B1906APO La Plata, Buenos Aires, Argentina; Universidad Nacional de La Plata, Facultad de Ciencias Naturales y Museo, calle 60 y 122, La Plata, Buenos Aires, Argentina.
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7
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Using telomeric chromosomal aberrations to evaluate clastogen-induced genomic instability in mammalian cells. Chromosome Res 2020; 28:259-276. [DOI: 10.1007/s10577-020-09641-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 09/06/2020] [Accepted: 09/06/2020] [Indexed: 12/13/2022]
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8
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Blackford AN, Stucki M. How Cells Respond to DNA Breaks in Mitosis. Trends Biochem Sci 2020; 45:321-331. [PMID: 32001093 DOI: 10.1016/j.tibs.2019.12.010] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 12/05/2019] [Accepted: 12/31/2019] [Indexed: 12/16/2022]
Abstract
DNA double-strand breaks (DSBs) are highly toxic lesions that can lead to chromosomal instability if they are not repaired correctly. DSBs are especially dangerous in mitosis when cells go through the complex process of equal chromosome segregation into daughter cells. When cells encounter DSBs in interphase, they are able to arrest the cell cycle until the breaks are repaired before entering mitosis. However, when DSBs occur during mitosis, cells no longer arrest but prioritize completion of cell division over repair of DNA damage. This review focuses on recent progress in our understanding of the mechanisms that allow mitotic cells to postpone DSB repair without accumulating massive chromosomal instability. Additionally, we review possible physiological consequences of failed DSB responses in mitosis.
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Affiliation(s)
- Andrew N Blackford
- Department of Oncology, MRC Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK; Cancer Research UK/MRC Oxford Institute for Radiation Oncology, University of Oxford, Oxford OX3 7DQ, UK.
| | - Manuel Stucki
- Department of Gynecology, University of Zurich, Wagistrasse 14, CH-8952 Schlieren, Switzerland.
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9
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Zhang M, Guo X, Gao Y, Lu D, Li W. Tumor Cell-Accelerated Senescence Is Associated With DNA-PKcs Status and Telomere Dysfunction Induced by Radiation. Dose Response 2018; 16:1559325818771527. [PMID: 29760601 PMCID: PMC5944147 DOI: 10.1177/1559325818771527] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 03/08/2018] [Accepted: 03/20/2018] [Indexed: 12/31/2022] Open
Abstract
Whether telomere structure integrity is related to radiosensitivity is not well investigated thus far. In this study, we investigated the relation between telomere instability and radiation-induced accelerated senescence. Partial knockdown of DNA-dependent catalytic subunit of protein kinase (DNA-PKcs) in human breast cancer cell line MCF-7 was established by small interfering RNA. Radiosensitivity of control and DNA-PKcs knockdown MCF-7 cells was analyzed by clonogenetic assay. Cell growth was measured by real-time cell electronic sensing. Senescence and apoptosis were evaluated by β-galactosidase histochemical staining and fluorescence-activated cell sorting, respectively. DNA damage was determined by long polymerase chain reaction (PCR). Telomere length and integrity were analyzed by real-time PCR and cytogenetic assay, respectively. DNA-PKcs knockdown MCF-7 cells were more sensitive to X-irradiation than control cells. Further investigation revealed that accelerated senescence is more pronounced than apoptosis in cells after radiation, particularly in DNA-PKcs knockdown cells. The cytogenetic assay and kinetics of DNA damage repair revealed that the role of telomere end-capping in DNA-PKcs, rather than DNA damage repair, was more relevant to radiosensitivity. To our knowledge, this is the first study to show that DNA-PKcs plays an important role in radiation-induced accelerated senescence via maintenance of telomere integrity in MCF-7 cells. These results could be useful for future understanding of the radiation-induced genome instability and its consequences.
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Affiliation(s)
- Miaomiao Zhang
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China.,College of Life Science, University of Chinese Academy of Sciences, Beijing, China
| | - Xiaopeng Guo
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China.,College of Life Science, University of Chinese Academy of Sciences, Beijing, China
| | - Yue Gao
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China.,College of Life Science, University of Chinese Academy of Sciences, Beijing, China
| | - Dong Lu
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China
| | - Wenjian Li
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China
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10
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Al-Mayah AHJ, Bright SJ, Bowler DA, Slijepcevic P, Goodwin E, Kadhim MA. Exosome-Mediated Telomere Instability in Human Breast Epithelial Cancer Cells after X Irradiation. Radiat Res 2016; 187:98-106. [PMID: 27959588 DOI: 10.1667/rr14201.1] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
In directly irradiating cells, telomere metabolism is altered and similar effects have been observed in nontargeted cells. Exosomes and their cargo play dominant roles in communicating radiation-induced bystander effects with end points related to DNA damage. Here we report novel evidence that exosomes are also responsible for inducing telomere-related bystander effects. Breast epithelial cancer cells were exposed to either 2 Gy X rays, or exposed to irradiated cell conditioned media (ICCM), or exosomes purified from ICCM. Compared to control cells, telomerase activity decreased in the 2 Gy irradiated cells and both bystander samples after one population doubling. At the first population doubling, telomere length was shorter in the 2 Gy irradiated sample but not in the bystander samples. By 24 population doublings telomerase activity recovered to control levels in all samples; however, the 2 Gy irradiated sample continued to demonstrate short telomeres and both bystander samples acquired shorter telomeres. RNase treatment of exosomes prevented the bystander effects on telomerase and telomere length that were observed at 1 population doubling and 24 population doublings, respectively. Thermal denaturation by boiling eliminated the reduction of telomere length in bystander samples, suggesting that the protein fraction of exosomes also contributes to the telomeric effect. RNase treatment plus boiling abrogated all telomere-related effects in directly irradiated and bystander cell populations. These findings suggest that both proteins and RNAs of exosomes can induce alterations in telomeric metabolism, which can instigate genomic instability in epithelial cancer cells after X-ray irradiation.
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Affiliation(s)
- Ammar H J Al-Mayah
- a Genomic Instability Group, Oxford Brookes University, Gipsy Lane Campus, Headington, Oxford OX3 0BP, United Kingdom
| | - Scott J Bright
- a Genomic Instability Group, Oxford Brookes University, Gipsy Lane Campus, Headington, Oxford OX3 0BP, United Kingdom
| | - Debbie A Bowler
- a Genomic Instability Group, Oxford Brookes University, Gipsy Lane Campus, Headington, Oxford OX3 0BP, United Kingdom
| | - Predrag Slijepcevic
- b Department of Life Sciences, College of Health and Life Sciences, Brunel University, London UB8 3PH, United Kingdom
| | - Edwin Goodwin
- c The New Mexico Consortium, Los Alamos, New Mexico 87544
| | - Munira A Kadhim
- a Genomic Instability Group, Oxford Brookes University, Gipsy Lane Campus, Headington, Oxford OX3 0BP, United Kingdom
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11
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Pascale RM, Joseph C, Latte G, Evert M, Feo F, Calvisi DF. DNA-PKcs: A promising therapeutic target in human hepatocellular carcinoma? DNA Repair (Amst) 2016; 47:12-20. [PMID: 27789167 DOI: 10.1016/j.dnarep.2016.10.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 10/11/2016] [Indexed: 12/27/2022]
Abstract
Hepatocellular carcinoma (HCC) is a frequent and deadly disease worldwide. The absence of effective therapies when the tumor is surgically unresectable leads to an extremely poor outcome of HCC patients. Thus, it is mandatory to elucidate the molecular pathogenesis of HCC in order to develop novel therapeutic strategies against this pernicious tumor. Mounting evidence indicates that suppression of the DNA damage response machinery might be deleterious for the survival and growth of the tumor cells. In particular, DNA dependent protein kinase catalytic subunit (DNA-PKcs), a major player in the non-homologous end-joining (NHEJ) repair process, seems to represent a valuable target for innovative anti-neoplastic therapies in cancer. DNA-PKcs levels are strongly upregulated and associated with a poor clinical outcome in various tumor types, including HCC. Importantly, DNA-PKcs not only protects tumor cells from harmful DNA insults coming either from the microenvironment or chemotherapeutic drug treatments, but also possesses additional properties, independent from its DNA repair activity, that provide growth advantages to cancer cells. These properties (metabolic and gene reprogramming, invasiveness and metastasis, resistance to apoptosis, etc.) have started to be elucidated. In the present review, we summarize the physiologic and oncogenic roles of DNA-PKcs, with a special emphasis on liver cancer. In particular, this work focuses on the molecular mechanism whereby DNA-PKcs exerts its pro-tumorigenic activity in cancer cells. In addition, the upstream regulator of DNA-PKcs activation as well as its downstream effectors thus far identified are illustrated. Furthermore, the potential therapeutic strategies aimed at inhibiting DNA-PKcs activity in HCC are discussed.
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Affiliation(s)
- Rosa M Pascale
- Department of Clinical and Experimental Medicine, University of Sassari, 07100 Sassari, Italy
| | - Christy Joseph
- Institute of Pathology, Universitätsmedizin Greifswald, 17489 Greifswald, Germany
| | - Gavinella Latte
- Department of Clinical and Experimental Medicine, University of Sassari, 07100 Sassari, Italy
| | - Matthias Evert
- Institute of Pathology, University of Regensburg, 93053 Regensburg, Germany
| | - Francesco Feo
- Department of Clinical and Experimental Medicine, University of Sassari, 07100 Sassari, Italy
| | - Diego F Calvisi
- Department of Clinical and Experimental Medicine, University of Sassari, 07100 Sassari, Italy; Institute of Pathology, Universitätsmedizin Greifswald, 17489 Greifswald, Germany.
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12
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DNA repair kinetics in SCID mice Sertoli cells and DNA-PKcs-deficient mouse embryonic fibroblasts. Chromosoma 2016; 126:287-298. [PMID: 27136939 PMCID: PMC5371645 DOI: 10.1007/s00412-016-0590-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Revised: 03/31/2016] [Accepted: 04/04/2016] [Indexed: 10/29/2022]
Abstract
Noncycling and terminally differentiated (TD) cells display differences in radiosensitivity and DNA damage response. Unlike other TD cells, Sertoli cells express a mixture of proliferation inducers and inhibitors in vivo and can reenter the cell cycle. Being in a G1-like cell cycle stage, TD Sertoli cells are expected to repair DSBs by the error-prone nonhomologous end-joining pathway (NHEJ). Recently, we have provided evidence for the involvement of Ku-dependent NHEJ in protecting testis cells from DNA damage as indicated by persistent foci of the DNA double-strand break (DSB) repair proteins phospho-H2AX, 53BP1, and phospho-ATM in TD Sertoli cells of Ku70-deficient mice. Here, we analyzed the kinetics of 53BP1 foci induction and decay up to 12 h after 0.5 Gy gamma irradiation in DNA-PKcs-deficient (Prkdc scid ) and wild-type Sertoli cells. In nonirradiated mice and Prkdc scid Sertoli cells displayed persistent DSBs foci in around 12 % of cells and a fivefold increase in numbers of these DSB DNA damage-related foci relative to the wild type. In irradiated mice, Prkdc scid Sertoli cells showed elevated levels of DSB-indicating foci in 82 % of cells 12 h after ionizing radiation (IR) exposure, relative to 52 % of irradiated wild-type Sertoli cells. These data indicate that Sertoli cells respond to and repair IR-induced DSBs in vivo, with repair kinetics being slow in the wild type and inefficient in Prkdc scid . Applying the same dose of IR to Prdkc -/- and Ku -/- mouse embryonic fibroblast (MEF) cells revealed a delayed induction of 53BP1 DSB-indicating foci 5 min post-IR in Prdkc -/- cells. Inefficient DSB repair was evident 7 h post-IR in DNA-PKcs-deficient cells, but not in Ku -/- MEFs. Our data show that quiescent Sertoli cells repair genotoxic DSBs by DNA-PKcs-dependent NEHJ in vivo with a slower kinetics relative to somatic DNA-PKcs-deficient cells in vitro, while DNA-PKcs deficiency caused inefficient DSB repair at later time points post-IR in both conditions. These observations suggest that DNA-PKcs contributes to the fast and slow repair of DSBs by NHEJ.
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13
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Vecoli C, Borghini A, Foffa I, Ait-Ali L, Picano E, Andreassi MG. Leukocyte telomere shortening in grown-up patients with congenital heart disease. Int J Cardiol 2016; 204:17-22. [DOI: 10.1016/j.ijcard.2015.11.133] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Revised: 11/19/2015] [Accepted: 11/22/2015] [Indexed: 01/31/2023]
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14
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Sishc BJ, Nelson CB, McKenna MJ, Battaglia CLR, Herndon A, Idate R, Liber HL, Bailey SM. Telomeres and Telomerase in the Radiation Response: Implications for Instability, Reprograming, and Carcinogenesis. Front Oncol 2015; 5:257. [PMID: 26636039 PMCID: PMC4656829 DOI: 10.3389/fonc.2015.00257] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 11/06/2015] [Indexed: 01/06/2023] Open
Abstract
Telomeres are nucleoprotein complexes comprised of tandem arrays of repetitive DNA sequence that serve to protect chromosomal termini from inappropriate degradation, as well as to prevent these natural DNA ends from being recognized as broken DNA (double-strand breaks) and triggering of inappropriate DNA damage responses. Preservation of telomere length requires telomerase, the specialized reverse transcriptase capable of maintaining telomere length via template-mediated addition of telomeric repeats onto the ends of newly synthesized chromosomes. Loss of either end-capping function or telomere length maintenance has been associated with genomic instability or senescence in a variety of settings; therefore, telomeres and telomerase have well-established connections to cancer and aging. It has long been recognized that oxidative stress promotes shortening of telomeres, and that telomerase activity is a radiation-inducible function. However, the effects of ionizing radiation (IR) exposure on telomeres per se are much less well understood and appreciated. To gain a deeper understanding of the roles, telomeres and telomerase play in the response of human cells to IRs of different qualities, we tracked changes in telomeric end-capping function, telomere length, and telomerase activity in panels of mammary epithelial and hematopoietic cell lines exposed to low linear energy transfer (LET) gamma(γ)-rays or high LET, high charge, high energy (HZE) particles, delivered either acutely or at low dose rates. In addition to demonstrating that dysfunctional telomeres contribute to IR-induced mutation frequencies and genome instability, we reveal non-canonical roles for telomerase, in that telomerase activity was required for IR-induced enrichment of mammary epithelial putative stem/progenitor cell populations, a finding also suggestive of cellular reprograming. Taken together, the results reported here establish the critical importance of telomeres and telomerase in the radiation response and, as such, have compelling implications not only for accelerated tumor repopulation following radiation therapy but also for carcinogenic potential following low dose exposures as well, including those of relevance to spaceflight-associated galactic cosmic radiations.
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Affiliation(s)
- Brock J Sishc
- Division of Molecular Radiation Oncology, Department of Radiation Oncology, University of Texas Southwestern Medical Center Dallas , Dallas, TX , USA ; Department of Environmental and Radiological Health Sciences, Colorado State University , Fort Collins, CO , USA
| | - Christopher B Nelson
- Department of Environmental and Radiological Health Sciences, Colorado State University , Fort Collins, CO , USA
| | - Miles J McKenna
- Department of Environmental and Radiological Health Sciences, Colorado State University , Fort Collins, CO , USA
| | - Christine L R Battaglia
- Department of Environmental and Radiological Health Sciences, Colorado State University , Fort Collins, CO , USA
| | - Andrea Herndon
- Department of Environmental and Radiological Health Sciences, Colorado State University , Fort Collins, CO , USA
| | - Rupa Idate
- Department of Environmental and Radiological Health Sciences, Colorado State University , Fort Collins, CO , USA
| | - Howard L Liber
- Department of Environmental and Radiological Health Sciences, Colorado State University , Fort Collins, CO , USA
| | - Susan M Bailey
- Department of Environmental and Radiological Health Sciences, Colorado State University , Fort Collins, CO , USA
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15
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Anjomani Virmouni S, Al-Mahdawi S, Sandi C, Yasaei H, Giunti P, Slijepcevic P, Pook MA. Identification of telomere dysfunction in Friedreich ataxia. Mol Neurodegener 2015; 10:22. [PMID: 26059974 PMCID: PMC4462004 DOI: 10.1186/s13024-015-0019-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 05/26/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Friedreich ataxia (FRDA) is a progressive inherited neurodegenerative disorder caused by mutation of the FXN gene, resulting in decreased frataxin expression, mitochondrial dysfunction and oxidative stress. A recent study has identified shorter telomeres in FRDA patient leukocytes as a possible disease biomarker. RESULTS Here we aimed to investigate both telomere structure and function in FRDA cells. Our results confirmed telomere shortening in FRDA patient leukocytes and identified similar telomere shortening in FRDA patient autopsy cerebellar tissues. However, FRDA fibroblasts showed significantly longer telomeres at early passage, occurring in the absence of telomerase activity, but with activation of an alternative lengthening of telomeres (ALT)-like mechanism. These cells also showed accelerated telomere shortening as population doubling increases. Furthermore, telomere dysfunction-induced foci (TIF) analysis revealed that FRDA fibroblasts have dysfunctional telomeres. CONCLUSIONS Our finding of dysfunctional telomeres in FRDA cells provides further insight into FRDA molecular disease mechanisms, which may have implications for future FRDA therapy.
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Affiliation(s)
- Sara Anjomani Virmouni
- Division of Biosciences, Department of Life Sciences, College of Health & Life Sciences, Brunel University London, Uxbridge, UB8 3PH, UK. .,Synthetic Biology Theme, Institute of Environment, Health & Societies, Brunel University London, Uxbridge, UK.
| | - Sahar Al-Mahdawi
- Division of Biosciences, Department of Life Sciences, College of Health & Life Sciences, Brunel University London, Uxbridge, UB8 3PH, UK. .,Synthetic Biology Theme, Institute of Environment, Health & Societies, Brunel University London, Uxbridge, UK.
| | - Chiranjeevi Sandi
- Division of Biosciences, Department of Life Sciences, College of Health & Life Sciences, Brunel University London, Uxbridge, UB8 3PH, UK. .,Current address: Uro-Oncology Research Group, Cancer Research UK-Cambridge Institute, University of Cambridge, Cambridge, UK.
| | - Hemad Yasaei
- Division of Biosciences, Department of Life Sciences, College of Health & Life Sciences, Brunel University London, Uxbridge, UB8 3PH, UK.
| | - Paola Giunti
- Department of Molecular Neuroscience, Institute of Neurology, University College London, Queen Square, London, UK.
| | - Predrag Slijepcevic
- Division of Biosciences, Department of Life Sciences, College of Health & Life Sciences, Brunel University London, Uxbridge, UB8 3PH, UK.
| | - Mark A Pook
- Division of Biosciences, Department of Life Sciences, College of Health & Life Sciences, Brunel University London, Uxbridge, UB8 3PH, UK. .,Synthetic Biology Theme, Institute of Environment, Health & Societies, Brunel University London, Uxbridge, UK.
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16
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Szumiel I. From radioresistance to radiosensitivity: In vitro evolution of L5178Y lymphoma. Int J Radiat Biol 2015; 91:465-71. [PMID: 25651039 DOI: 10.3109/09553002.2014.996263] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
PURPOSE To discuss the possible reasons for the loss of tumourigenicity and the acquisition of new phenotypic features (among them, sensitivity to X and UVC radiations) as a result of in vitro cultivation of L5178Y lymphoma cells. RESULTS Ten years ago the phenotypic differences between LY-R (original L5178Y maintained in vivo and examined in vitro) and LY-S lines were reviewed in detail by the author. The loss of tumourigenicity of LY-R cells upon in vitro cultivation accompanying the acquirement of the LY-S phenotype had been described earlier by Beer et al. (1983). In spite of their common origin, the sublines were shown to differ in their relative sensitivity to a number of DNA damaging agents and in numerous other features. Here, selected differences between LY-R and LY-S lines are briefly reviewed. It is proposed that Wallace's concept (2010a) that mitochondria are the interface between environmental conditions and the genome may explain the LY-R-LY-S conversion under prolonged in vitro cultivation. CONCLUSION The differences between the LY lines were probably of epigenetic rather than genetic character. The properties of LY-R cells changed as a result of exposure to an oxic in vitro milieu. The changes could be preconditioned by heteroplasmy and the selection of cells endowed with mitochondria best fitted to a high oxygen-low carbon dioxide environment.
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Affiliation(s)
- Irena Szumiel
- Centre for Radiobiology and Biological Dosimetry, Institute of Nuclear Chemistry and Technology , Warsaw , Poland
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17
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Sridharan DM, Asaithamby A, Bailey SM, Costes SV, Doetsch PW, Dynan WS, Kronenberg A, Rithidech KN, Saha J, Snijders AM, Werner E, Wiese C, Cucinotta FA, Pluth JM. Understanding cancer development processes after HZE-particle exposure: roles of ROS, DNA damage repair and inflammation. Radiat Res 2015; 183:1-26. [PMID: 25564719 DOI: 10.1667/rr13804.1] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
During space travel astronauts are exposed to a variety of radiations, including galactic cosmic rays composed of high-energy protons and high-energy charged (HZE) nuclei, and solar particle events containing low- to medium-energy protons. Risks from these exposures include carcinogenesis, central nervous system damage and degenerative tissue effects. Currently, career radiation limits are based on estimates of fatal cancer risks calculated using a model that incorporates human epidemiological data from exposed populations, estimates of relative biological effectiveness and dose-response data from relevant mammalian experimental models. A major goal of space radiation risk assessment is to link mechanistic data from biological studies at NASA Space Radiation Laboratory and other particle accelerators with risk models. Early phenotypes of HZE exposure, such as the induction of reactive oxygen species, DNA damage signaling and inflammation, are sensitive to HZE damage complexity. This review summarizes our current understanding of critical areas within the DNA damage and oxidative stress arena and provides insight into their mechanistic interdependence and their usefulness in accurately modeling cancer and other risks in astronauts exposed to space radiation. Our ultimate goals are to examine potential links and crosstalk between early response modules activated by charged particle exposure, to identify critical areas that require further research and to use these data to reduced uncertainties in modeling cancer risk for astronauts. A clearer understanding of the links between early mechanistic aspects of high-LET response and later surrogate cancer end points could reveal key nodes that can be therapeutically targeted to mitigate the health effects from charged particle exposures.
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Affiliation(s)
- D M Sridharan
- a Lawrence Berkeley National Laboratory, Berkeley, California
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18
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The DNA-dependent protein kinase: A multifunctional protein kinase with roles in DNA double strand break repair and mitosis. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2014; 117:194-205. [PMID: 25550082 DOI: 10.1016/j.pbiomolbio.2014.12.003] [Citation(s) in RCA: 198] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Revised: 12/16/2014] [Accepted: 12/19/2014] [Indexed: 11/21/2022]
Abstract
The DNA-dependent protein kinase (DNA-PK) is a serine/threonine protein kinase composed of a large catalytic subunit (DNA-PKcs) and the Ku70/80 heterodimer. Over the past two decades, significant progress has been made in elucidating the role of DNA-PK in non-homologous end joining (NHEJ), the major pathway for repair of ionizing radiation-induced DNA double strand breaks in human cells and recently, additional roles for DNA-PK have been reported. In this review, we will describe the biochemistry, structure and function of DNA-PK, its roles in DNA double strand break repair and its newly described roles in mitosis and other cellular processes.
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19
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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: 7] [Impact Index Per Article: 0.7] [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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20
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Urushibara A, Kodama S, Yokoya A. Induction of genetic instability by transfer of a UV-A-irradiated chromosome. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2014; 766:29-34. [DOI: 10.1016/j.mrgentox.2014.02.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Revised: 01/20/2014] [Accepted: 02/07/2014] [Indexed: 01/03/2023]
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21
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Krutikov K, Zheng Y, Chesney A, Huang X, Vaags AK, Evdokimova V, Hough MR, Chen E. Ectopic TLX1 expression accelerates malignancies in mice deficient in DNA-PK. PLoS One 2014; 9:e89649. [PMID: 24586935 PMCID: PMC3935916 DOI: 10.1371/journal.pone.0089649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Accepted: 01/26/2014] [Indexed: 11/22/2022] Open
Abstract
The noncluster homeobox gene HOX11/TLX1 (TLX1) is detected at the breakpoint of the t(10;14)(q24;q11) chromosome translocation in patients with T cell acute lymphoblastic leukemia (T-ALL). This translocation results in the inappropriate expression of TLX1 in T cells. The oncogenic potential of TLX1 was demonstrated in IgHμ-TLX1Tg mice which develop mature B cell lymphoma after a long latency period, suggesting the requirement of additional mutations to initiate malignancy. To determine whether dysregulation of genes involved in the DNA damage response contributed to tumor progression, we crossed IgHμ-TLX1Tg mice with mice deficient in the DNA repair enzyme DNA-PK (PrkdcScid/Scid mice). IgHµ-TLX1TgPrkdcScid/Scid mice developed T-ALL and acute myeloid leukemia (AML) with reduced latency relative to control PrkdcScid/Scid mice. Further analysis of thymi from premalignant mice revealed greater thymic cellularity concomitant with increased thymocyte proliferation and decreased apoptotic index. Moreover, premalignant and malignant thymocytes exhibited impaired spindle checkpoint function, in association with aneuploid karyotypes. Gene expression profiling of premalignant IgHµ-TLX1TgPrkdcScid/Scid thymocytes revealed dysregulated expression of cell cycle, apoptotic and mitotic spindle checkpoint genes in double negative 2 (DN2) and DN3 stage thymocytes. Collectively, these findings reveal a novel synergy between TLX1 and impaired DNA repair pathway in leukemogenesis.
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Affiliation(s)
- Konstantin Krutikov
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
- Department of Molecular and Cellular Biology, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Yanzhen Zheng
- Department of Molecular and Cellular Biology, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Alden Chesney
- Department of Clinical Pathology, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - Xiaoyong Huang
- Department of Molecular and Cellular Biology, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Andrea K. Vaags
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
- Department of Molecular and Cellular Biology, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Valentina Evdokimova
- Department of Molecular and Cellular Biology, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Margaret R. Hough
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
- * E-mail: (EC); (MRH)
| | - Edwin Chen
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
- Department of Molecular and Cellular Biology, Sunnybrook Research Institute, Toronto, Ontario, Canada
- * E-mail: (EC); (MRH)
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22
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Targeting human telomeric G-quadruplex DNA and inhibition of telomerase activity with [(dmb)2Ru(obip)Ru(dmb)2](4+). PLoS One 2013; 8:e84419. [PMID: 24386376 PMCID: PMC3874006 DOI: 10.1371/journal.pone.0084419] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Accepted: 11/14/2013] [Indexed: 11/19/2022] Open
Abstract
Inhibition of telomerase by inducing/stabilizing G-quadruplex formation is a promising strategy to design new anticancer drugs. We synthesized and characterized a new dinuclear complex [(dmb)2Ru(obip)Ru(dmb)2]4+ (dmb = 4,4’-dimethyl-2,2’-bipyridine, obip = (2-(2-pyridyl)imidazo[4,5-f][1,10]phenanthroline) with high affinity for both antiparallel and mixed parallel / antiparallel G-quadruplex DNA. This complex can promote the formation and stabilize G-quadruplex DNA. Dialysis and TRAP experiments indicated that [(dmb)2Ru(obip)Ru(dmb)2]4+ acted as an excellent telomerase inhibitor due to its obvious selectivity for G-quadruplex DNA rather than double stranded DNA. In vitro co-culture experiments implied that [(dmb)2Ru(obip)Ru(dmb)2]4+ inhibited telomerase activity and hindered cancer cell proliferation without side effects to normal fibroblast cells. TUNEL assay indicated that inhibition of telomerase activity induced DNA cleavage further apoptosis in cancer cells. Therefore, RuII complex represents an exciting opportunity for anticancer drug design by specifically targeting cancer cell G-quadruplexes DNA.
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23
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Kjeldsen E, Kallenbach M. Duplication of isodicentric chromosome 13, idic(13)(p11.2), leading to pentasomy 13q in acute myeloid leukemia without maturation. Cytogenet Genome Res 2013; 140:21-8. [PMID: 23615042 DOI: 10.1159/000350694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Isodicentric chromosome 13, idic(13)(p11.2), is a very rare chromosomal aberration in acute myeloid leukemia (AML). We describe here a novel case of AML without maturation, where the leukemic cells harbored double idic(13)(p11.2) and a normal chromosome 13 resulting in pentasomy 13q. Analyses were done on aspirated bone marrow cells from diagnosis. We utilized G-banding analysis, 24-color karyotyping and additional FISH analyses with various locus-specific probes to characterize the chromosomal complement. Oligonucleotide-based 180K aCGH analysis was done to search for submicroscopic imbalances. The karyotype was 47,XY,idic(13)(p11.2)x2[23]/46,XY[2]. Pantelomeric FISH analysis indicated critically short telomeres. Oligo-based aCGH analysis confirmed high copy gain of chromosome 13q and did not disclose other genomic imbalances. Reviewing the literature, this may be the second case of pentasomy 13q, since idic(13)(p11.2), when analyzed by conventional cytogenetics, is indistinguishable from i(13)(q10). Both cases were associated with immature AML and a poor outcome. We propose that idic(13)(p11.2) is a new recurrent abnormality in AML without maturation and suggest that pentasomy 13q is an early event in pathogenesis of AML through amplification of genes located on 13q.
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Affiliation(s)
- E Kjeldsen
- Cancer Cytogenetics Laboratory, Department of Hematology, Aarhus University Hospital, DK-8000 Aarhus, Denmark.
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24
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Ray FA, Zimmerman E, Robinson B, Cornforth MN, Bedford JS, Goodwin EH, Bailey SM. Directional genomic hybridization for chromosomal inversion discovery and detection. Chromosome Res 2013; 21:165-74. [PMID: 23572395 PMCID: PMC3627024 DOI: 10.1007/s10577-013-9345-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Revised: 02/28/2013] [Accepted: 03/12/2013] [Indexed: 12/18/2022]
Abstract
Chromosomal rearrangements are a source of structural variation within the genome that figure prominently in human disease, where the importance of translocations and deletions is well recognized. In principle, inversions—reversals in the orientation of DNA sequences within a chromosome—should have similar detrimental potential. However, the study of inversions has been hampered by traditional approaches used for their detection, which are not particularly robust. Even with significant advances in whole genome approaches, changes in the absolute orientation of DNA remain difficult to detect routinely. Consequently, our understanding of inversions is still surprisingly limited, as is our appreciation for their frequency and involvement in human disease. Here, we introduce the directional genomic hybridization methodology of chromatid painting—a whole new way of looking at structural features of the genome—that can be employed with high resolution on a cell-by-cell basis, and demonstrate its basic capabilities for genome-wide discovery and targeted detection of inversions. Bioinformatics enabled development of sequence- and strand-specific directional probe sets, which when coupled with single-stranded hybridization, greatly improved the resolution and ease of inversion detection. We highlight examples of the far-ranging applicability of this cytogenomics-based approach, which include confirmation of the alignment of the human genome database and evidence that individuals themselves share similar sequence directionality, as well as use in comparative and evolutionary studies for any species whose genome has been sequenced. In addition to applications related to basic mechanistic studies, the information obtainable with strand-specific hybridization strategies may ultimately enable novel gene discovery, thereby benefitting the diagnosis and treatment of a variety of human disease states and disorders including cancer, autism, and idiopathic infertility.
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Affiliation(s)
- F Andrew Ray
- Department of Environmental & Radiological Health Sciences, Colorado State University, Fort Collins, CO 80523-1618, USA
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25
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PARP1 and DNA-PKcs synergize to suppress p53 mutation and telomere fusions during T-lineage lymphomagenesis. Oncogene 2012; 32:1761-71. [PMID: 22614020 DOI: 10.1038/onc.2012.199] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Poly(ADP-ribose) polymerase 1 (PARP1) interacts genetically with the DNA-dependent protein kinase catalytic subunit (DNA-PKcs) to suppress early-onset T-lineage lymphomas in the mouse, but the underlying mechanisms have remained unknown. To address this question, we analyzed a series of lymphomas arising in PARP1(-/-)/DNA-PKcs(-/-) (P1(-/-)/D(-/-)) mice. We found that, despite defective V(D)J recombination, P1(-/-)/D(-/-) lymphomas lacked clonal reciprocal translocations involving antigen-receptor loci. Instead, tumor cells were characterized by aneuploidy driven by two main mechanisms: p53 inactivation and abnormal chromosome disjunction due to telomere fusions (TFs). Aberrant accumulation of p53 was observed in 13/19 (68.4%) lymphomas. Sequence analysis revealed five p53 mutations: three missense point mutations (one transition in exon 8 and two transversions in exons 5 and 8, respectively), one in-frame 5-11 microindel in exon 7 and a 410-bp deletion encompassing exons 5-8, resulting in a truncated protein. Analysis of tumor metaphases using sequential telomere fluorescent in-situ hybridization and spectral karyotyping revealed that nine out of nine lymphomas contained TFs. Mutant but not wild-type p53 status was associated with frequent clonal and nonclonal TFs, suggesting that p53 normally limits the extent of telomere dysfunction during transformation. Chromosomes involved in TFs were more likely to be aneuploid than chromosomes not involved in TFs in the same metaphases, regardless of the p53 status, indicating that TFs promote aneuploidy via a mechanism that is distinct from p53 loss. Finally, analysis of radiation responses in P1(-/-)/D(-/-), and control primary cells and tissues indicates that loss of PARP1 increases in vivo radiosensitivity and genomic instability in DNA-PKcs-deficient mice without impairing p53 stabilization and effector functions, suggesting a more severe defect in double-strand break (DSB) repair in double mutants. Together, our findings uncover defective DSB repair leading to tumor suppressor inactivation and abnormal segregation of fused chromosomes as two novel mechanisms promoting tumorigenesis in thymocytes lacking PARP1 and DNA-PKcs.
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Jia G, Su L, Singhal S, Liu X. Emerging roles of SIRT6 on telomere maintenance, DNA repair, metabolism and mammalian aging. Mol Cell Biochem 2012; 364:345-50. [DOI: 10.1007/s11010-012-1236-8] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Accepted: 01/13/2012] [Indexed: 01/23/2023]
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27
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Sapir E, Gozaly-Chianea Y, Al-Wahiby S, Ravindran S, Yasaei H, Slijepcevic P. Effects of BRCA2 deficiency on telomere recombination in non-ALT and ALT cells. Genome Integr 2011; 2:9. [PMID: 22152194 PMCID: PMC3264516 DOI: 10.1186/2041-9414-2-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Accepted: 12/09/2011] [Indexed: 12/29/2022] Open
Abstract
Background Recent studies suggest that BRCA2 affects telomere maintenance. Interestingly, anti cancer treatments that involve BRCA2 and telomerase individually are currently being explored. In the light of the above recent studies their combinatorial targeting may be justified in the development of future treatments. In order to investigate effects of BRCA2 that can be explored for this combinatorial targeting we focused on the analysis of recombination rates at telomeres by monitoring T-SCEs (Telomere Sister Chromatid Exchanges). Results We observed a significant increase in T-SCE frequencies in four BRCA2 defective human cell lines thus suggesting that BRCA2 suppresses recombination at telomeres. To test this hypothesis further we analyzed T-SCE frequencies in a set of Chinese hamster cell lines with or without functional BRCA2. Our results indicate that introduction of functional BRCA2 normalizes frequencies of T-SCEs thus supporting the notion that BRCA2 suppresses recombination at telomeres. Given that ALT (Alternative Lengthening of Telomeres) positive cells maintain telomeres by recombination we investigated the effect of BRCA2 depletion in these cells. Our results show that this depletion causes a dramatic reduction in T-SCE frequencies in ALT positive cells, but not in non-ALT cells. Conclusion BRCA2 suppresses recombination at telomeres in cells that maintain them by conventional mechanisms. Furthermore, BRCA2 depletion in ALT positive cells reduces high levels of T-SCEs normally found in these cells. Our results could be potentially important for refining telomerase-based anti-cancer therapies.
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Affiliation(s)
- Ester Sapir
- Brunel Institute of Cancer Genetics and Pharmacogenomics, Division of Biosciences, School of Health Sciences & Social Care, Brunel University, Uxbridge, Middlesex, UB8 3PH, UK.
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Kasparek TR, Humphrey TC. DNA double-strand break repair pathways, chromosomal rearrangements and cancer. Semin Cell Dev Biol 2011; 22:886-97. [PMID: 22027614 DOI: 10.1016/j.semcdb.2011.10.007] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Revised: 10/07/2011] [Accepted: 10/12/2011] [Indexed: 01/12/2023]
Abstract
Chromosomal rearrangements, which can lead to oncogene activation and tumour suppressor loss, are a hallmark of cancer cells. Such outcomes can result from both the repair and misrepair of DNA ends, which arise from a variety of lesions including DNA double strand breaks (DSBs), collapsed replication forks and dysfunctional telomeres. Here we review the mechanisms by which non-homologous end joining (NHEJ) and homologous recombination (HR) repair pathways can both promote chromosomal rearrangements and also suppress them in response to such lesions, in accordance with their increasingly recognised tumour suppressor function. Further, we consider how chromosomal rearrangements, together with a modular approach towards understanding their etiology, may be exploited for cancer therapy.
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Affiliation(s)
- Torben R Kasparek
- CRUK/MRC Gray Institute for Radiation Oncology and Biology, Department of Oncology, University of Oxford, Oxford, UK
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Bodvarsdottir SK, Steinarsdottir M, Bjarnason H, Eyfjord JE. Dysfunctional telomeres in human BRCA2 mutated breast tumors and cell lines. Mutat Res 2011; 729:90-9. [PMID: 22019625 DOI: 10.1016/j.mrfmmm.2011.10.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Revised: 08/16/2011] [Accepted: 10/06/2011] [Indexed: 10/16/2022]
Abstract
In the present study the possible involvement of telomeres in chromosomal instability of breast tumors and cell lines from BRCA2 mutation carriers was examined. Breast tumors from BRCA2 mutation carriers showed significantly higher frequency of chromosome end-to-end fusions (CEFs) than tumors from non-carriers despite normal telomere DNA content. Frequent CEFs were also found in four different BRCA2 heterozygous breast epithelial cell lines, occasionally with telomere signal at the fusion point, indicating telomere capping defects. Extrachromosomal telomeric repeat (ECTR) DNA was frequently found scattered around metaphase chromosomes and interstitial telomere sequences (ITSs) were also common. Telomere sister chromatid exchanges (T-SCEs), characteristic of cells using alternative lengthening of telomeres (ALT), were frequently detected in all heterozygous BRCA2 cell lines as well as the two ALT positive cell lines tested. Even though T-SCE frequency was similar in BRCA2 heterozygous and ALT positive cell lines they differed in single telomere signal loss and ITSs. Chromatid type alterations were more prominent in the BRCA2 heterozygous cell lines that may have propensity for telomere based chromosome healing. Telomere dysfunction-induced foci (TIFs) formation, identified by co-localization of telomeres and γ-H2AX, supported telomere associated DNA damage response in BRCA2 heterozygous cell lines. TIFs were found in interphase nuclei, at chromosome ends, ITSs and ECTR DNA. In conclusion, our results suggest that BRCA2 has an important role in telomere stabilization by repressing CEFs through telomere capping and the prevention of telomere loss by replication stabilization.
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30
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Bolzán AD. Chromosomal aberrations involving telomeres and interstitial telomeric sequences. Mutagenesis 2011; 27:1-15. [PMID: 21857006 DOI: 10.1093/mutage/ger052] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Telomeres are specialised nucleoproteic complexes localised at the physical ends of linear eukaryotic chromosomes that maintain their stability and integrity. In vertebrate chromosomes, the DNA component of telomeres is constituted by (TTAGGG)n repeats, which can be localised at the terminal regions of chromosomes (true telomeres) or at intrachromosomal sites (interstitial telomeric sequences or ITSs, located at the centromeric region or between the centromere and the telomere). In the past two decades, the use of molecular cytogenetic techniques has led to a new spectrum of spontaneous and clastogen-induced chromosomal aberrations being identified, involving telomeres and ITSs. Some aberrations involve the chromosome ends and, indirectly, the telomeric repeats located at the terminal regions of chromosomes (true telomeres). A second type of aberrations directly involves the telomeric sequences located at the chromosome ends. Finally, there is a third class of aberrations that specifically involves the ITSs. The aims of this review are to provide a detailed description of these aberrations and to summarise the available data regarding their induction by physical and chemical mutagens.
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Affiliation(s)
- Alejandro D Bolzán
- La Carrera del Investigador Científico y Tecnológico del CONICET, Argentina, Laboratorio de Citogenética y Mutagénesis, Instituto Multidisciplinario de Biología Celular (CCT-CONICET La Plata-CICPBA), C.C. 403, 1900 La Plata, Argentina.
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Dregalla RC, Zhou J, Idate RR, Battaglia CLR, Liber HL, Bailey SM. Regulatory roles of tankyrase 1 at telomeres and in DNA repair: suppression of T-SCE and stabilization of DNA-PKcs. Aging (Albany NY) 2011; 2:691-708. [PMID: 21037379 PMCID: PMC2993799 DOI: 10.18632/aging.100210] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Intrigued by the dynamics of the seemingly contradictory yet integrated cellular responses to the requisites of preserving telomere integrity while also efficiently repairing damaged DNA, we investigated roles of the telomere associated poly(adenosine diphosphate [ADP]-ribose) polymerase (PARP) tankyrase 1 in both telomere function and the DNA damage response following exposure to ionizing radiation. Tankyrase 1 siRNA knockdown in human cells significantly elevated recombination specifically within telomeres, a phenotype with the potential of accelerating cellular senescence. Additionally, depletion of tankyrase 1 resulted in concomitant and rapid reduction of the nonhomologous end-joining protein DNA-PKcs, while Ku86 and ATM protein levels remained unchanged; DNA-PKcs mRNA levels were also unaffected. We found that the requirement of tankyrase 1 for DNA-PKcs protein stability reflects the necessity of its PARP enzymatic activity. We also demonstrated that depletion of tankyrase 1 resulted in proteasome-mediated DNA-PKcs degradation, explaining the associated defective damage response observed; i.e., increased sensitivity to ionizing radiation-induced cell killing, mutagenesis, chromosome aberration and telomere fusion. We provide the first evidence for regulation of DNA-PKcs by tankyrase 1 PARP activity and taken together, identify roles of tankyrase 1 with implications not only for DNA repair and telomere biology, but also for cancer and aging.
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Affiliation(s)
- Ryan C Dregalla
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, 80523-1618, USA
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Martínez-A C, van Wely KHM. Centromere fission, not telomere erosion, triggers chromosomal instability in human carcinomas. Carcinogenesis 2011; 32:796-803. [PMID: 21478459 PMCID: PMC3106440 DOI: 10.1093/carcin/bgr069] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The majority of sporadic carcinomas suffer from a kind of genetic instability in which chromosome number changes occur together with segmental defects. This means that changes involving intact chromosomes accompany breakage-induced alterations. Whereas the causes of aneuploidy are described in detail, the origins of chromosome breakage in sporadic carcinomas remain disputed. The three main pathways of chromosomal instability (CIN) proposed until now (random breakage, telomere fusion and centromere fission) are largely based on animal models and in vitro experiments, and recent studies revealed several discrepancies between animal models and human cancer. Here, we discuss how the experimental systems translate to human carcinomas and compare the theoretical breakage products to data from patient material and cancer cell lines. The majority of chromosomal defects in human carcinomas comprises pericentromeric breaks that are captured by healthy telomeres, and only a minor proportion of chromosome fusions can be attributed to telomere erosion or random breakage. Centromere fission, not telomere erosion, is therefore the most probably trigger of CIN and early carcinogenesis. Similar centromere–telomere fusions might drive a subset of congenital defects and evolutionary chromosome changes.
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Affiliation(s)
- Carlos Martínez-A
- Department of Immunology and Oncology, Centro Nacional de Biotecnología (CNB-CSIC), Darwin 3, UAM Campus Cantoblanco, 28049 Madrid, Spain
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Fabre KM, Ramaiah L, Dregalla RC, Desaintes C, Weil MM, Bailey SM, Ullrich RL. Murine Prkdc polymorphisms impact DNA-PKcs function. Radiat Res 2011; 175:493-500. [PMID: 21265624 DOI: 10.1667/rr2431.1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Polymorphic variants of DNA repair genes can increase the carcinogenic potential of exposure to ionizing radiation. Two single nucleotide polymorphisms (SNPs) in Prkdc, the gene encoding the DNA-dependent protein kinase catalytic subunit (DNA-PKcs), have been identified in BALB/c mice and linked to reduced DNA-PKcs activity and mammary cancer susceptibility. We examined three additional mouse strains to better define the roles of the BALB/c Prkdc SNPs (R2140C and M3844V). One is a congenic strain (C.B6) that has the C57BL/6 Prkdc allele on a BALB/c background, and the other is a congenic strain (B6.C) that has the BALB/c variant Prkdc allele on a C57BL/6 background. We also examined the LEWES mouse strain, which possesses only one of the BALB/c Prkdc SNPs (M3844V). Our results demonstrate that both Prkdc SNPs are responsible for deficient DNA-PKcs protein expression, DNA repair and telomere function, while the LEWES SNP affects only DNA-PKcs expression and repair capacity. These studies provide insight into the separation of function between the two BALB/c SNPs as well as direct evidence that SNPs positioned within Prkdc can significantly influence DNA-PKcs function involving DNA repair capacity, telomere end-capping, and potentially cancer susceptibility.
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Affiliation(s)
- Kristin M Fabre
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado 80523, USA
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Abstract
Fluorescence in situ hybridization (FISH) has become a powerful tool for exploring genomes at the level of chromosomes. The procedure can be used to identify individual chromosomes, rearrangements between chromosomes, and the location within a chromosome of specific DNA sequences such as centromeres, telomeres, and even individual genes. Chromosome orientation FISH (CO-FISH) extends the information obtainable from standard FISH to include the relative orientation of two or more DNA sequences within a chromosome (Goodwin and Meyne, Cytogenet Cell Genet 63:126-127, 1993). In combination with a suitable reference probe, CO-FISH can also determine the absolute 5'-3' direction of a DNA sequence relative to the short arm (pter) to long arm (qter) axis of the chromosome. This variation of CO-FISH was originally termed "COD-FISH" (Chromosome orientation and direction FISH) to reflect this fact (Meyne and Goodwin, Chromosome Research 3:375-378, 1995). Telomeric DNA serves as a convenient and absolute reference probe for this purpose, since all G-rich 5'-(TTAGGG)( n )-3' telomeric sequences are terminally located and oriented away from the centromere.In the beginning, CO-FISH was used to detect obligate chromosomal inversions associated with isochromosome formation (Bailey et al., Mutagenesis 11:139-144, 1996), various pericentric inversions (Bailey et al., Cytogenetics and Cell Genetics 75:248-253, 1996), and to confirm the origin of centromeric lateral asymmetry (Goodwin et al., Chromosoma 104:345-347, 1996). More recent and sophisticated applications of CO-FISH include distinction between telomeres produced via leading- vs. lagging-strand DNA synthesis (Bailey et al., Science 293:2462-2465, 2001), identification of interstitial blocks of telomere sequence that result from inappropriate fusion to double-strand breaks (telomere-DSB fusion) (Bailey et al., DNA Repair (Amst) 3:349-357, 2004), discovery of elevated rates of mitotic recombination at chromosomal termini (Cornforth and Eberle, Mutagenesis, 16:85-89, 2001) and sister chromatid exchange within telomeric DNA (T-SCE) (Bailey et al., Nucleic Acids Res 32:3743-3751, 2004), establishing replication timing of mammalian telomeres throughout S-phase (ReD-FISH) (Cornforth et al., In: Cold Spring Harbor Symposium: Telomeres and Telomerase, Cold Spring Harbor, NY, 2003; Zou et al., Proc Natl Acad Sci USA 101:12928-12933, 2004) and in combination with -spectral karyotyping (SKY-CO-FISH) (Williams et al., Cancer Res 69:2100-2107, 2009). For more information, the reader is referred to several reviews (Bailey et al., Cytogenet Genome Res 107, 14-17, 2004; Bailey and Cornforth, Cell Mol Life Sci 64:2956-2964, 2007; Bailey, Telomeres and Double-Strand Breaks - All's Well that "Ends" Well, Radiat Res 169:1-7, 2008).
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Affiliation(s)
- Eli S Williams
- Department of Environmental & Radiological Health Sciences, Colorado State University, Fort Collins, CO, USA
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Zhou FX, Xiong J, Luo ZG, Dai J, Yu HJ, Liao ZK, Lei H, Xie CH, Zhou YF. cDNA Expression Analysis of a Human Radiosensitive-Radioresistant Cell Line Model Identifies Telomere Function as a Hallmark of Radioresistance. Radiat Res 2010; 174:550-7. [DOI: 10.1667/rr1657.1] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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36
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Williams ES, Bailey SM. Chromosome orientation fluorescence in situ hybridization (CO-FISH). Cold Spring Harb Protoc 2010; 2009:pdb.prot5269. [PMID: 20147245 DOI: 10.1101/pdb.prot5269] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- Eli S Williams
- Drug Discovery Department, Moffitt Cancer Center, Tampa, FL 33612, USA.
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Chapman KL, Kelly JW, Lee R, Goodwin EH, Kadhim MA. Tracking genomic instability within irradiated and bystander populations. J Pharm Pharmacol 2010; 60:959-68. [DOI: 10.1211/jpp.60.8.0003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Abstract
Over the past two decades, our understanding of radiation biology has undergone a fundamental shift in paradigms away from deterministic ‘hit-effect’ relationships and towards complex ongoing ‘cellular responses’. These responses include now familiar, but still poorly understood, phenomena associated with radiation exposure such as genomic instability and bystander effects. Although these responses share some common features (e.g. they occur at high frequency following very low doses, are heterogeneous in their induction and are observed at time points far removed from the initial radiation exposure), the precise relationship between genomic instability and bystander effects remains to be elucidated. This review will provide a synthesis of the known, and proposed, interrelationships among irradiated and bystander cellular responses to radiation. It also discusses our current experimental approach for gaining a clearer understanding of the relationship between damage induction and long-term effects in both irradiated and bystander cells.
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Affiliation(s)
- Kim L Chapman
- School of Life Sciences, Oxford Brookes University, Oxford, OX3 0BP, UK
| | - James W Kelly
- School of Life Sciences, Oxford Brookes University, Oxford, OX3 0BP, UK
| | - Ryonfa Lee
- Gesellschaft für Schwerionenforschung mbH (GSI), Planckstr. 1, 64291 Darmstadt, Germany
| | - Edwin H Goodwin
- Bioscience Division, Los Alamos National Laboratory, MS M-888, Los Alamos, NM 87545, USA
| | - Munira A Kadhim
- School of Life Sciences, Oxford Brookes University, Oxford, OX3 0BP, UK
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Bailey SM, Williams ES, Cornforth MN, Goodwin EH. Chromosome Orientation fluorescence in situ hybridization or strand-specific FISH. Methods Mol Biol 2010; 659:173-83. [PMID: 20809311 DOI: 10.1007/978-1-60761-789-1_12] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Chromosome Orientation FISH (CO-FISH) is a technique that can be used to extend the information obtainable from standard FISH to include the relative orientation of two or more DNA sequences within a chromosome. CO-FISH can determine the absolute 5'-to-3' direction of a DNA sequence relative to the short arm-to-long arm axis of the chromosome, and so was originally termed "COD-FISH" (Chromosome Orientation and Direction FISH). CO-FISH has been employed to detect chromosomal inversions associated with isochromosome formation, various pericentric inversions, and to confirm the origin of lateral asymmetry. More recent and sophisticated applications of CO-FISH include distinction between telomeres produced via leading- vs. lagging-strand DNA synthesis, identification of interstitial blocks of telomere sequence that result from inappropriate fusion to double-strand breaks (telomere-DSB fusion), discovery of elevated rates of mitotic recombination at chromosomal termini and sister chromatid exchange within telomeric DNA (T-SCE), establishing replication timing of mammalian telomeres throughout S-phase (ReD-FISH) and to identify chromosomes, in combination with spectral karyotyping (SKY-CO-FISH).
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Affiliation(s)
- Susan M Bailey
- Department of Environmental & Radiological Health Sciences, Colorado State University, Fort Collins, CO, USA.
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Williams ES, Klingler R, Ponnaiya B, Hardt T, Schrock E, Lees-Miller SP, Meek K, Ullrich RL, Bailey SM. Telomere dysfunction and DNA-PKcs deficiency: characterization and consequence. Cancer Res 2009; 69:2100-7. [PMID: 19244120 DOI: 10.1158/0008-5472.can-08-2854] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The mechanisms by which cells accurately distinguish between DNA double-strand break (DSB) ends and telomeric DNA ends remain poorly defined. Recent investigations have revealed intriguing interactions between DNA repair and telomeres. We were the first to report a requirement for the nonhomologous end-joining (NHEJ) protein DNA-dependent protein kinase (DNA-PK) in the effective end-capping of mammalian telomeres. Here, we report our continued characterization of uncapped (as opposed to shortened) dysfunctional telomeres in cells deficient for the catalytic subunit of DNA-PK (DNA-PKcs) and shed light on their consequence. We present evidence in support of our model that uncapped telomeres in this repair-deficient background are inappropriately detected and processed as DSBs and thus participate not only in spontaneous telomere-telomere fusion but, importantly, also in ionizing radiation-induced telomere-DSB fusion events. We show that phosphorylation of DNA-PKcs itself (Thr-2609 cluster) is a critical event for proper telomere end-processing and that ligase IV (NHEJ) is required for uncapped telomere fusion. We also find uncapped telomeres in cells from the BALB/c mouse, which harbors two single-nucleotide polymorphisms that result in reduced DNA-PKcs abundance and activity, most markedly in mammary tissue, and are both radiosensitive and susceptible to radiogenic mammary cancer. Our results suggest mechanistic links between uncapped/dysfunctional telomeres in DNA-PKcs-deficient backgrounds, radiation-induced instability, and breast cancer. These studies provide the first direct evidence of genetic susceptibility and environmental insult interactions leading to a unique and ongoing form of genomic instability capable of driving carcinogenesis.
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Affiliation(s)
- Eli S Williams
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado 80523-1618, USA
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40
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Jeggo PA. Genomic instability in cancer development. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2008; 570:175-97. [PMID: 18727501 DOI: 10.1007/1-4020-3764-3_6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Penny A Jeggo
- Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton, UK
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41
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Bailey SM. Telomeres and Double-Strand Breaks – All's Well that “Ends” Well. …. Radiat Res 2008; 169:1-7. [DOI: 10.1667/rr1197.1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2007] [Accepted: 09/24/2007] [Indexed: 11/03/2022]
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42
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Karenko L, Hahtola S, Ranki A. Molecular cytogenetics in the study of cutaneous T-cell lymphomas (CTCL). Cytogenet Genome Res 2007; 118:353-61. [DOI: 10.1159/000108320] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2006] [Accepted: 11/30/2006] [Indexed: 01/06/2023] Open
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Riha K, Heacock ML, Shippen DE. The role of the nonhomologous end-joining DNA double-strand break repair pathway in telomere biology. Annu Rev Genet 2007; 40:237-77. [PMID: 16822175 DOI: 10.1146/annurev.genet.39.110304.095755] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Double-strand breaks are a cataclysmic threat to genome integrity. In higher eukaryotes the predominant recourse is the nonhomologous end-joining (NHEJ) double-strand break repair pathway. NHEJ is a versatile mechanism employing the Ku heterodimer, ligase IV/XRCC4 and a host of other proteins that juxtapose two free DNA ends for ligation. A critical function of telomeres is their ability to distinguish the ends of linear chromosomes from double-strand breaks, and avoid NHEJ. Telomeres accomplish this feat by forming a unique higher order nucleoprotein structure. Paradoxically, key components of NHEJ associate with normal telomeres and are required for proper length regulation and end protection. Here we review the biochemical mechanism of NHEJ in double-strand break repair, and in the response to dysfunctional telomeres. We discuss the ways in which NHEJ proteins contribute to telomere biology, and highlight how the NHEJ machinery and the telomere complex are evolving to maintain genome stability.
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Affiliation(s)
- Karel Riha
- Gregor Mendel Institute of Plant Molecular Biology, Austrian Academy of Sciences, A-1030 Vienna, Austria.
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Schwartz JL. Variability: the common factor linking low dose-induced genomic instability, adaptation and bystander effects. Mutat Res 2006; 616:196-200. [PMID: 17145066 DOI: 10.1016/j.mrfmmm.2006.11.016] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The characteristics of low dose radiation-induced genomic instability, adaptive responses, and bystander effects were compared in order to probe possible underlying mechanisms, and develop models for predicting response to in vivo low dose radiation exposures. While there are some features that are common to all three (e.g., absence of a true dose-response, the multiple endpoints affected by each), other characteristics appear to distinguish one from the other (e.g., TP53 involvement, LET response, influence of DNA repair). Each of the responses is also highly variable; not all cell and tissue models show the same response and there is much interindividual variation in response. Most of these studies have employed in vitro cell culture or tissue explant models, and understanding underlying mechanisms and the biological significance of these low dose-responses will require study of tissue-specific in vivo endpoints. The in vitro studies strongly suggest that modeling low dose radiation effects will be a complex process, and will likely require separate study of each of these low dose phenomena. Knowledge of instability responses, for example, may not aid in predicting other low dose effects in the same tissue.
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Affiliation(s)
- Jeffrey L Schwartz
- Department of Radiation Oncology, University of Washington Medical Center, 1959 NE Pacific, Box 356069, Seattle, WA 98195-6069, USA.
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Zhang Y, Zhou J, Cao X, Zhang Q, Lim CUK, Ullrich RL, Bailey SM, Liber HL. Partial deficiency of DNA-PKcs increases ionizing radiation-induced mutagenesis and telomere instability in human cells. Cancer Lett 2006; 250:63-73. [PMID: 17095151 DOI: 10.1016/j.canlet.2006.09.021] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2006] [Revised: 09/14/2006] [Accepted: 09/22/2006] [Indexed: 12/21/2022]
Abstract
The correct repair of DNA double-strand breaks (DSBs) is essential to maintaining the integrity of the genome. Misrepair of DSBs is detrimental to cells and organisms, leading to gene mutation, chromosomal aberration, and cancer development. Nonhomologous end-joining (NHEJ) is one of the principal rejoining processes in most higher eukaryotic cells. NHEJ is facilitated by DNA-dependent protein kinase (DNA-PK), which is composed of a catalytic subunit, DNA-PKcs, and the heterodimeric DNA binding regulatory complex Ku70/86. Null mutation of DNA-PKcs leads to immunodeficiency, chromosomal aberration, gene mutation, telomeric end-capping failure, and cancer predisposition in animals and cells. However, it is unknown whether partial deficiency of DNA-PKcs as might occur in a fraction of the population (e.g., heterozygotes), influences cellular function. Using small interfering RNA (siRNA) transfection, we established partial deficiency of DNA-PKcs in human cells, ranging from 4 to 85% of control levels. Our results reveal for the first time, that partial deficiency of DNA-PKcs leads to increased ionizing radiation (IR)-induced mutagenesis, cell killing, and telomere dysfunction. Radiation mutagenesis was increased inversely with DNA-PKcs protein level, with the most pronounced effect being observed in cells with protein levels below 50% of controls. A small but statistically significant increase in IR-induced cell killing was observed as DNA-PKcs levels decreased, over the entire range of protein levels. Frequencies of IR-induced telomere-DSB fusion was increased at levels of DNA-PKcs as low as approximately 50%, similar to what would be expected in heterozygous individuals. Taken together, our results suggest that even partial deficiency of DNA repair proteins may represent a considerable risk to genomic stability.
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Affiliation(s)
- Ying Zhang
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO 80521, USA.
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46
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Machella N, Battino M, Pisanelli B, Regoli F. Influence of the SCGE protocol on the amount of basal DNA damage detected in the Mediterranean mussel, Mytilus galloprovincialis. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2006; 47:579-86. [PMID: 16795087 DOI: 10.1002/em.20231] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Genotoxicity studies using the single cell gel electrophoresis (SCGE) assay indicate that basal levels of DNA strand breaks (SBs) in marine invertebrates are higher and more variable than those in marine vertebrates. This elevated level of DNA damage was attributed to a large number of alkali-labile sites, which are characteristic of the tightly-packaged DNA in invertebrate cells. To investigate if altering the SCGE protocol can artificially modulate high levels of SBs, SCGE experiments were performed on haemocytes from the Mediterranean mussel (Mytilus galloprovincialis) using proteinase K (PK) digestion in combination with assay buffers containing various concentrations of EDTA. In addition, the effects of Trolox (soluble antioxidant) and aurintricarboxylic acid (ATA; inhibitor of Ca(2+)/Mg(2+)-dependent nucleases) also were tested. The levels of SBs in M. galloprovincialis cells were compared with SBs in cells from a terrestrial mollusk (the snail Helix aspersa), and a teleost fish (the seabass Dicentrarchus labrax). The integrity of M. galloprovincialis DNA isolated with phenol extractions using EDTA, Trolox, and ATA was further assayed by gel electrophoresis. High SBs in mussel cells were reduced by combining EDTA with PK digestion, or using Trolox or ATA during cell processing for the SCGE assay. Snails and seabass had lower levels of SBs in the SCGE assay, and the levels were not affected by the protocol modifications. Adding EDTA, Trolox, or ATA to phenol extractions of M. galloprovincialis genomic DNA also reduced the extent of DNA fragmentation. These results suggest that the internal fluids of M. galloprovincialis may increase the basal levels of DNA SBs through oxidative and/or enzyme-mediated pathways. M. galloprovincialis is used extensively as a sentinel species for assessing the genotoxic hazard of marine pollutants. Our data suggest that the SCGE protocol should be carefully considered when assessing DNA damage in these species.
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Affiliation(s)
- Nicola Machella
- Istituto di Biologia e Genetica, Università Politecnica delle Marche, Ancona, Italy.
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47
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Bailey SM, Bedford JS. Studies on chromosome aberration induction: What can they tell us about DNA repair? DNA Repair (Amst) 2006; 5:1171-81. [PMID: 16814619 DOI: 10.1016/j.dnarep.2006.05.033] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Many, if not the majority of spontaneous or induced mutations in somatic mammalian cells associated with cancer are large chromosome level changes. For exposure to carcinogenic agents, certain specific chromosomal aberrations are likely to lie early along the pathway leading from initial molecular damage to cancer. The kinds of aberrations that occur, and the positions of breakpoints involved in their formation, can reveal not only genes and controlling elements whose expression or suppression underlie the molecular nature of the initiation of malignant transformation, but also how structural and functional features of chromatin can affect processes involved in repair or mis-repair of initial DNA damage. Thus, cytogenetics can provide information in ways that are not readily appreciated in studies requiring disruption of chromatin organization as it exists in the cell and its tissue context, and where DNA repair assays measure effects averaged over the entire genome. Examples include the fact that in contrast to a more efficient repair of single strand or base damage in transcriptionally active chromatin, after ionizing radiation exposure, the preponderance of translocation breakpoints indicating mis-repair occur in transcriptionally active or potentially active chromatin. Cytogenetic studies have led to the recognition that processing of DNA ends - both ends resulting from breaks along chromosomes and natural chromosomal termini, or telomeres - share very interesting similarities and differences. Further, direct observation of chromatin in cells during interphase can speak directly to early stages of aberration formation where processes occur within the context of intact cells, and to the role (or lack thereof) of cell cycle checkpoint responses that often accompany DNA damage. The superior resolution of many of the current molecular cytogenetics approaches, combined with immunocytochemical detection of proteins involved in DNA damage processing, and the availability of repair deficient mutants or knockdown strategies such as RNA interference, suggest that cytogenetics may still provide useful information and set certain restrictions important for rational interpretation of studies of DNA repair and associated protein interactions that can only be carried out in vitro. The intent of this paper is to focus on contributions of studies on the production of chromosomal aberrations following ionizing radiation exposure regarding important insights on associated DNA repair processes involved, and further, on guidelines or constraints they provide for the interpretation of in vitro DNA repair studies that would have been difficult to appreciate without the cytogenetics. We will first briefly summarize some early studies that serve as a reminder of the background on which current studies are based, and then carry forward to the present day certain interesting facets of these studies.
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Abstract
Controversy surrounding the proposed mechanism of radiation-induced translocation has existed virtually since the inception of radiation genetics/cytogenetics, some 75 years ago. Chief among these controversies is how close chromosomes have to be to one another at the time of exposure for an exchange to occur. An historically related issue, and one that continues to generate lively debate, is whether both chromosomes participating in an exchange must sustain radiation damage, or whether instead a single damaged site on one chromosome is sufficient. The intent of this paper is to present one person's perspective as we revisit these two long-standing issues, armed with more recent knowledge in three key areas. These include a new-found appreciation for the complexity of chromosome rearrangements; molecular processes of recombination that are likely to be involved; and the architecture of the nucleus regarding the relationship among chromosomes during interphase.
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Affiliation(s)
- Michael N Cornforth
- Department of Radiation Oncology, University of Texas Medical Branch, Galveston, TX 77555-0884, USA.
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Krishnaja AP, Sharma NK. Differential radiation effects in smokers--culture time dependence of the yield of gamma ray-induced chromosome damage in first division metaphases. Int J Radiat Biol 2006; 82:363-77. [PMID: 16782654 DOI: 10.1080/09553000600774097] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
PURPOSE Telomeric associations (TA) and unstable chromosomal aberration (CA) transmission through M1-M4 metphases (first to fourth division) in gamma-ray irradiated G0 lymphocytes in 2 smokers were examined, since TA in conventionally stained chromosomes were reported earlier as a sensitive cytogenetic marker in mutagen-exposed populations. The purpose of the present study is an extension of our earlier studies on unstable CA transmission through successive mitotic divisions. MATERIALS AND METHODS The bromodeoxyuridine (BrdU) incorporation and fluorescence plus giemsa (FPG) method for M1-M5 metaphase analysis was carried out at 50, 72, 96 h to analyse TA and CA in conventionally and FPG stained chromosomes after irradiation of human blood samples with 3 Gy of gamma-rays. In situ hybridization (ISH) with enzymatic/fluorescence detection was used to analyse radiation-induced aneuploidy and TA. Analysis was carried out on sister chromatid exchanges (SCE) in M2 cells at 72 h and micronuclei (MN) at 24, 50, 72, 96 h. RESULTS TA, corroborated by the absence of acentric fragments, were not detected in conventional/FPG stained/ISH chromosomes. Chromosome 21 aneuploidy was observed. Significant differences in mean frequencies of dicentrics/micronuclei (MN)/SCE with high frequency cells (HFC) were found in smokers after irradiation compared to non-smokers. Higher radiation induced CA in M1 cells were found with extended culture time. Induction of giant cells with mirror dicentrics, tricentrics and rings were found. CONCLUSION TA in conventional or FPG stained metaphase chromosomes is not a sensitive cytogenetic marker for mutagen exposed population screening. Higher radiation induced CA frequencies in M1 cells with extended culture time were indicative of a delay in cell cycle progression of aberrant cells or different lymphocyte subset populations. Bridge-breakage-fusion (BBF) events due to dicentrics may be instrumental in the perpetuation of chromosomal instability. Differential effects were noted in radiation-induced dicentric, SCE and MN frequencies in smokers compared to non-smokers. Heavy smoking could be a confounding variable in chromosome-based biodosimetry and biomonitoring studies. Giant cells may denote a switch to amitotic modes of cell survival, providing additional mechanisms of genotoxic resistance.
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Affiliation(s)
- Ayyathan P Krishnaja
- Genetic Toxicology and Chromosome Studies Section, Radiation Biology and Health Sciences Division, Bhabha Atomic Research Centre, Mumbai, India.
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Zhang Y, Zhou J, Lim CU. The role of NBS1 in DNA double strand break repair, telomere stability, and cell cycle checkpoint control. Cell Res 2006; 16:45-54. [PMID: 16467875 DOI: 10.1038/sj.cr.7310007] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The genomes of eukaryotic cells are under continuous assault by environmental agents and endogenous metabolic byproducts. Damage induced in DNA usually leads to a cascade of cellular events, the DNA damage response. Failure of the DNA damage response can lead to development of malignancy by reducing the efficiency and fidelity of DNA repair. The NBS1 protein is a component of the MRE11/RAD50/NBS1 complex (MRN) that plays a critical role in the cellular response to DNA damage and the maintenance of chromosomal integrity. Mutations in the NBS1 gene are responsible for Nijmegen breakage syndrome (NBS), a hereditary disorder that imparts an increased predisposition to development of malignancy. The phenotypic characteristics of cells isolated from NBS patients point to a deficiency in the repair of DNA double strand breaks. Here, we review the current knowledge of the role of NBS1 in the DNA damage response. Emphasis is placed on the role of NBS1 in the DNA double strand repair, modulation of the DNA damage sensing and signaling, cell cycle checkpoint control and maintenance of telomere stability.
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Affiliation(s)
- Ying Zhang
- Department of Environmental and Radiological Health Science, Colorado State University, Fort Collins, 80523, USA.
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