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Bailey SM, Cross EM, Kinner-Bibeau L, Sebesta HC, Bedford JS, Tompkins CJ. Monitoring Genomic Structural Rearrangements Resulting from Gene Editing. J Pers Med 2024; 14:110. [PMID: 38276232 PMCID: PMC10817574 DOI: 10.3390/jpm14010110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 01/04/2024] [Accepted: 01/13/2024] [Indexed: 01/27/2024] Open
Abstract
The cytogenomics-based methodology of directional genomic hybridization (dGH) enables the detection and quantification of a more comprehensive spectrum of genomic structural variants than any other approach currently available, and importantly, does so on a single-cell basis. Thus, dGH is well-suited for testing and/or validating new advancements in CRISPR-Cas9 gene editing systems. In addition to aberrations detected by traditional cytogenetic approaches, the strand specificity of dGH facilitates detection of otherwise cryptic intra-chromosomal rearrangements, specifically small inversions. As such, dGH represents a powerful, high-resolution approach for the quantitative monitoring of potentially detrimental genomic structural rearrangements resulting from exposure to agents that induce DNA double-strand breaks (DSBs), including restriction endonucleases and ionizing radiations. For intentional genome editing strategies, it is critical that any undesired effects of DSBs induced either by the editing system itself or by mis-repair with other endogenous DSBs are recognized and minimized. In this paper, we discuss the application of dGH for assessing gene editing-associated structural variants and the potential heterogeneity of such rearrangements among cells within an edited population, highlighting its relevance to personalized medicine strategies.
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Affiliation(s)
- Susan M. Bailey
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO 80523, USA;
- KromaTiD, Inc., Longmont, CO 80501, USA; (E.M.C.); (L.K.-B.); (H.C.S.)
| | - Erin M. Cross
- KromaTiD, Inc., Longmont, CO 80501, USA; (E.M.C.); (L.K.-B.); (H.C.S.)
| | | | - Henry C. Sebesta
- KromaTiD, Inc., Longmont, CO 80501, USA; (E.M.C.); (L.K.-B.); (H.C.S.)
| | - Joel S. Bedford
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO 80523, USA;
- KromaTiD, Inc., Longmont, CO 80501, USA; (E.M.C.); (L.K.-B.); (H.C.S.)
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Dicentric chromosome assay using a deep learning-based automated system. Sci Rep 2022; 12:22097. [PMID: 36543843 PMCID: PMC9772420 DOI: 10.1038/s41598-022-25856-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 12/06/2022] [Indexed: 12/24/2022] Open
Abstract
The dicentric chromosome assay is the "gold standard" in biodosimetry for estimating radiation exposure. However, its large-scale deployment is limited owing to its time-consuming nature and requirement for expert reviewers. Therefore, a recently developed automated system was evaluated for the dicentric chromosome assay. A previously constructed deep learning-based automatic dose-estimation system (DLADES) was used to construct dose curves and calculate estimated doses. Blood samples from two donors were exposed to cobalt-60 gamma rays (0-4 Gy, 0.8 Gy/min). The DLADES efficiently identified monocentric and dicentric chromosomes but showed impaired recognition of complete cells with 46 chromosomes. We estimated the chromosome number of each "Accepted" sample in the DLADES and sorted similar-quality images by removing outliers using the 1.5IQR method. Eleven of the 12 data points followed Poisson distribution. Blind samples were prepared for each dose to verify the accuracy of the estimated dose generated by the curve. The estimated dose was calculated using Merkle's method. The actual dose for each sample was within the 95% confidence limits of the estimated dose. Sorting similar-quality images using chromosome numbers is crucial for the automated dicentric chromosome assay. We successfully constructed a dose-response curve and determined the estimated dose using the DLADES.
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Differential Radiosensitizing Effect of 50 nm Gold Nanoparticles in Two Cancer Cell Lines. BIOLOGY 2022; 11:biology11081193. [PMID: 36009820 PMCID: PMC9404963 DOI: 10.3390/biology11081193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 07/19/2022] [Accepted: 08/08/2022] [Indexed: 11/17/2022]
Abstract
Simple Summary Nanoparticle treatment on tumor cells is proposed for its potential radiosensitizing properties, increasing the radiation effect on tumor cells and reducing the adverse effects on healthy tissues. The present study evaluates, on two cell lines derived from colon and breast adenocarcinomas, the impact of irradiation in the presence of specifically targeted gold nanoparticles. Cells were irradiated in the absence and in the presence of non-functionalized or specifically functionalized gold nanoparticles. The results pointed out that actively targeting gold nanoparticles has a clear radiosensitizing effect in both cell lines. Abstract Radiation therapy is widely used as an anti-neoplastic treatment despite the adverse effects it can cause in non-tumoral tissues. Radiosensitizing agents, which can increase the effect of radiation in tumor cells, such as gold nanoparticles (GNPs), have been described. To evaluate the radiosensitizing effect of 50 nm GNPs, we carried out a series of studies in two neoplastic cell lines, Caco2 (colon adenocarcinoma) and SKBR3 (breast adenocarcinoma), qualitatively evaluating the internalization of the particles, determining with immunofluorescence the number of γ-H2AX foci after irradiation with ionizing radiation (3 Gy) and evaluating the viability rate of both cell lines after treatment by means of an MTT assay. Nanoparticle internalization varied between cell lines, though they both showed higher internalization degrees for functionalized GNPs. The γ-H2AX foci counts for the different times analyzed showed remarkable differences between cell lines, although they were always significantly higher for functionalized GNPs in both lines. Regarding cell viability, in most cases a statistically significant decreasing tendency was observed when treated with GNPs, especially those that were functionalized. Our results led us to conclude that, while 50 nm GNPs induce a clear radiosensitizing effect, it is highly difficult to describe the magnitude of this effect as universal because of the heterogeneity found between cell lines.
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Pakniyat F, Nedaie HA, Mozdarani H, Mahmoudzadeh A, Gholami S. Evaluation of Capability and Relationship of Different Radiobiological Endpoints for Radiosensitivity Prediction in Human Tumor Cell Lines Compared with Clonogenic Survival. J Biomed Phys Eng 2022; 12:127-136. [PMID: 35433526 PMCID: PMC8995752 DOI: 10.31661/jbpe.v0i0.1263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 11/03/2019] [Indexed: 06/14/2023]
Abstract
BACKGROUND Establishing a predictive assay of radiosensitivity (as an appropriate, practical and cost-effective method) has been challenging. OBJECTIVE The purpose of this study is to evaluate the capability and relationship of various endpoints, including GammaH2AX, micronuclei; and apoptosis in determining the human tumor cell lines radiosensitivities compared with clonogenic survival. MATERIAL AND METHODS In an experimental in-vitro study, the response of carcinoma cell lines of HN5 and HeLa to 2 Gy of 6 MV photon beam was investigated via various assays. RESULTS Survival fraction at 2 Gy (SF2) of HeLa and HN5 was indicated as 0.42 ± 0.06 and 0.5 ± 0.03 respectively, proposing more radioresistance of HN5. This finding was confirmed with "2 Gy apoptosis enhancement ratio" which was 1.77 and 1.42 in HeLa and HN5. The increased levels of DNA DSBs were observed after irradiation; significant in HeLa with enhancement rate of 19.24. The micronuclei formation followed an ascending trend post irradiation; but with the least difference between two cells. Although the relationship between micronuclei and clonogenic survival was moderate (R2 = 0.35), a good correlation was observed between apoptosis and clonogenic survival (R2 = 0.71). CONCLUSION The results of studied endpoints agreed with the SF2, highlighting their capabilities in radiosensitivity prediction. In terms of the enhancement ratio, gammaH2AX foci scoring could be a valid indicator of radiosensitivity but not the exact surrogate marker of survival because no correlation was observed. Moreover, considering the chief determents comprising lack of time and money, the apoptotic induction might be an appropriate indicator with the best correlation coefficient.
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Affiliation(s)
- Fatemeh Pakniyat
- PhD, Department of Medical Physics and Biomedical Engineering, Tehran University of Medical Sciences, Tehran, Iran
| | - Hassan Ali Nedaie
- PhD, Department of Medical Physics and Biomedical Engineering, Tehran University of Medical Sciences, Tehran, Iran
- PhD, Radiation Oncology Research Center, Cancer institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Hossein Mozdarani
- PhD, Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Aziz Mahmoudzadeh
- PhD, Department of Bioscience and Biotechnology, Malek-Ashtar University of Technology, Tehran, Iran
| | - Somayeh Gholami
- PhD, Radiation Oncology Research Center, Cancer institute, Tehran University of Medical Sciences, Tehran, Iran
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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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Soni A, Murmann-Konda T, Magin S, Iliakis G. A method for the cell-cycle-specific analysis of radiation-induced chromosome aberrations and breaks. Mutat Res 2019; 815:10-19. [PMID: 30999232 DOI: 10.1016/j.mrfmmm.2019.04.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 03/30/2019] [Accepted: 04/01/2019] [Indexed: 06/09/2023]
Abstract
The classical G2-assay is widely used to assess cell-radiosensitivity and cancer phenotype: Cells are exposed to low doses of ionizing-radiation (IR) and collected for cytogenetic- analysis ˜1.5 h later. In this way, chromosome-damage is measured in cells irradiated in G2-phase, without retrieving information regarding kinetics of chromosome-break-repair. Modification of the assay to include analysis at multiple time-points after IR, has enabled kinetic-analysis of chromatid-break-repair and assessment of damage in a larger proportion of G2-phase cells. This modification, however, increases the probability that at later time points not only cells irradiated in G2-phase, but also cells irradiated in S-phase will reach metaphase. However, the response of cells irradiated in G2-phase can be mechanistically different from that of cells irradiated in S-phase. Therefore, indiscriminate analysis may confound the interpretation of experiments designed to elucidate mechanisms of chromosome-break-repair and the contributions of the different DSB-repair-pathways in this response. Here we report an EdU based modification of the assay that enables S- and G2-phase specific analysis of chromatid break repair. Our results show that the majority of metaphases captured during the first 2 h after IR originate from cells irradiated in G2-phase (EdU- metaphases) in both rodent and human cells. Metaphases originating from cells irradiated in S-phase (EdU+ metaphases) start appearing at 2 h and 4 h after IR in rodent and human cells, respectively. The kinetics of chromatid-break-repair are similar in cells irradiated in G2- and S-phase of the cell-cycle, both in rodent and human cells. The protocol is applicable to classical-cytogenetic experiments and allows the cell-cycle specific analysis of chromosomal-aberrations. Finally, the protocol can be applied to the kinetic analysis of chromosome-breaks in prematurely-condensed-chromosomes of G2-phase cells. In summary, the developed protocol provides means to enhance the analysis of IR-induced-cytogenetic-damage by providing information on the cell-cycle phase where DNA damage is inflicted.
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Affiliation(s)
- Aashish Soni
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, Essen, Germany
| | - Tamara Murmann-Konda
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, Essen, Germany
| | - Simon Magin
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, Essen, Germany
| | - George Iliakis
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, Essen, Germany.
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Shibata A, Jeggo P. A historical reflection on our understanding of radiation-induced DNA double strand break repair in somatic mammalian cells; interfacing the past with the present. Int J Radiat Biol 2019; 95:945-956. [PMID: 30608893 DOI: 10.1080/09553002.2018.1564083] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Purpose: The International Journal of Radiation Biology (IJRB) is celebrating 60 years of publishing in 2019. IJRB has made an enormous contribution to publishing papers that have enhanced our understanding of the DNA damage response (DDR) activated following exposure to ionizing radiation (IR). The IR-induced DDR field has a rich history but many outstanding papers pass unread by young scientists overwhelmed by the current literature. We provide a historical reflection on key advances in the DDR field and interface them with current knowledge. Conclusions: DNA double strand breaks (DSBs) were identified as the major biological lesion induced by IR. But early studies on cells from IR-sensitive ataxia telangiectasia patients showed that DSB repair was not sufficient to prevent IR hypersensitivity. Subsequently, the ATM-dependent signal transduction process was revealed, with the breadth of the response being slowly unearthed. Early studies demonstrated at least two processes of DSB repair and revealed that mis-repair causes translocation formation. Recent studies, however, are unraveling more complexity in the repair process, including the specific processing of DSBs within transcriptionally active regions, and the significance of the chromatin environment. Despite the quality of these early and current studies, many questions remain to be addressed.
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Affiliation(s)
- Atsushi Shibata
- a Education and Research Support Center , Gunma University Graduate School of Medicine , Gunma , Maebashi , Japan
| | - Penny Jeggo
- b Genome Damage and Stability Centre, School of Life Sciences , University of Sussex , Brighton , UK
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Burdak-Rothkamm S, Rothkamm K. Radiation-induced bystander and systemic effects serve as a unifying model system for genotoxic stress responses. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2018; 778:13-22. [DOI: 10.1016/j.mrrev.2018.08.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 08/13/2018] [Accepted: 08/15/2018] [Indexed: 12/19/2022]
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Tassano M, Oddone N, Fernández M, Porcal W, García MF, Martínez-López W, Benech JC, Cabral P. Evaluation of chromosomal aberrations induced by 188Re-dendrimer nanosystem on B16f1 melanoma cells. Int J Radiat Biol 2018; 94:664-670. [PMID: 29775404 DOI: 10.1080/09553002.2018.1478161] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
PURPOSE To study the rhenium-188 labeling of polyamidoamine (PAMAM) generation 4 (G4) dendrimer and its evaluation on biodistribution and chromosomal aberrations in melanoma cells induced by ionizing radiation as potential treatment agent. MATERIALS AND METHODS Dendrimers were first conjugated with Suc-HYNIC (succinimidyl 6-hydrazinopyridine-3-carboxylic acid hydrochloride). Dendrimer-HYNIC was then incubated with 188ReO4-. Biodistribution was performed administrating 188Re-dendrimer to normal (NM) or melanoma-bearing mice (MBM). Chromosome aberration test was conducted in order to measure treatment capacity of 188Re-dendrimer in melanoma cells. RESULTS Radiolabeling yield of dendrimer was approx. 70%. Biodistribution studies in NM showed blood clearance with hepatic and renal depuration. MBM showed a similar pattern of biodistribution with tumor uptake of 6% of injected dose. Aberrant metaphases quantified in control cells were 7%, increasing to 29.5% in cells treated with 15μCi (0.555 MBq) of 188Re-dendrimer for 24 h. CONCLUSIONS 188Re-dendrimer can produce double-stranded breaks in DNA induced by ionizing radiation in melanoma cells in vitro.
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Affiliation(s)
- Marcos Tassano
- a Area de Radiofarmacia, Facultad de Ciencias , Centro de Investigaciones Nucleares, Universidad de la República , Montevideo , Uruguay
| | - Natalia Oddone
- b Laboratorio de Señalización Celular y Nanobiología , Instituto de Investigaciones Biológicas Clemente Estable, Ministerio de Educación y Cultura , Montevideo , Uruguay
| | - Marcelo Fernández
- a Area de Radiofarmacia, Facultad de Ciencias , Centro de Investigaciones Nucleares, Universidad de la República , Montevideo , Uruguay
| | - Williams Porcal
- d Departamento de Química Orgánica, Facultad de Química , Universidad de la República , Montevideo , Uruguay
| | - María Fernanda García
- a Area de Radiofarmacia, Facultad de Ciencias , Centro de Investigaciones Nucleares, Universidad de la República , Montevideo , Uruguay
| | - Wilner Martínez-López
- c Laboratorio de Epigenética e Inestabilidad Genómica , Instituto de Investigaciones Biológicas Clemente Estable, Ministerio de Educación y Cultura , Montevideo , Uruguay
| | - Juan Claudio Benech
- b Laboratorio de Señalización Celular y Nanobiología , Instituto de Investigaciones Biológicas Clemente Estable, Ministerio de Educación y Cultura , Montevideo , Uruguay
| | - Pablo Cabral
- a Area de Radiofarmacia, Facultad de Ciencias , Centro de Investigaciones Nucleares, Universidad de la República , Montevideo , Uruguay
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Habash M, Bohorquez LC, Kyriakou E, Kron T, Martin OA, Blyth BJ. Clinical and Functional Assays of Radiosensitivity and Radiation-Induced Second Cancer. Cancers (Basel) 2017; 9:cancers9110147. [PMID: 29077012 PMCID: PMC5704165 DOI: 10.3390/cancers9110147] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 10/24/2017] [Accepted: 10/24/2017] [Indexed: 01/10/2023] Open
Abstract
Whilst the near instantaneous physical interaction of radiation energy with living cells leaves little opportunity for inter-individual variation in the initial yield of DNA damage, all the downstream processes in how damage is recognized, repaired or resolved and therefore the ultimate fate of cells can vary across the population. In the clinic, this variability is observed most readily as rare extreme sensitivity to radiotherapy with acute and late tissue toxic reactions. Though some radiosensitivity can be anticipated in individuals with known genetic predispositions manifest through recognizable phenotypes and clinical presentations, others exhibit unexpected radiosensitivity which nevertheless has an underlying genetic cause. Currently, functional assays for cellular radiosensitivity represent a strategy to identify patients with potential radiosensitivity before radiotherapy begins, without needing to discover or evaluate the impact of the precise genetic determinants. Yet, some of the genes responsible for extreme radiosensitivity would also be expected to confer susceptibility to radiation-induced cancer, which can be considered another late adverse event associated with radiotherapy. Here, the utility of functional assays of radiosensitivity for identifying individuals susceptible to radiotherapy-induced second cancer is discussed, considering both the common mechanisms and important differences between stochastic radiation carcinogenesis and the range of deterministic acute and late toxic effects of radiotherapy.
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Affiliation(s)
- Mohammad Habash
- Cancer Research Division, Peter MacCallum Cancer Centre, 305 Grattan Street, Parkville, VIC 3000, Australia.
- Faculty of Medicine, Dentistry & Health Sciences, The University of Melbourne, Parkville, VIC 3010, Australia.
| | - Luis C Bohorquez
- Physical Sciences, Peter MacCallum Cancer Centre, 305 Grattan Street, Parkville, VIC 3000, Australia.
| | - Elizabeth Kyriakou
- Physical Sciences, Peter MacCallum Cancer Centre, 305 Grattan Street, Parkville, VIC 3000, Australia.
| | - Tomas Kron
- Physical Sciences, Peter MacCallum Cancer Centre, 305 Grattan Street, Parkville, VIC 3000, Australia.
| | - Olga A Martin
- Cancer Research Division, Peter MacCallum Cancer Centre, 305 Grattan Street, Parkville, VIC 3000, Australia.
- Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, 305 Grattan Street, Parkville, VIC 3000, Australia.
- The Sir Peter MacCallum Department of Oncology, The University of Melbourne, Parkville, VIC 3010, Australia.
| | - Benjamin J Blyth
- Cancer Research Division, Peter MacCallum Cancer Centre, 305 Grattan Street, Parkville, VIC 3000, Australia.
- Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, 305 Grattan Street, Parkville, VIC 3000, Australia.
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Somaiah N, Rothkamm K, Yarnold J. Where Do We Look for Markers of Radiotherapy Fraction Size Sensitivity? Clin Oncol (R Coll Radiol) 2015; 27:570-8. [PMID: 26108884 DOI: 10.1016/j.clon.2015.06.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Revised: 03/31/2015] [Accepted: 06/06/2015] [Indexed: 02/06/2023]
Abstract
The response of human normal tissues to radiotherapy fraction size is often described in terms of cellular recovery, but the causal links between cellular and tissue responses to ionising radiation are not necessarily straightforward. This article reviews the evidence for a cellular basis to clinical fractionation sensitivity in normal tissues and discusses the significance of a long-established inverse association between fractionation sensitivity and proliferative indices. Molecular mechanisms of fractionation sensitivity involving DNA damage repair and cell cycle control are proposed that will probably require modification before being applicable to human cancer. The article concludes by discussing the kind of correlative research needed to test for and validate predictive biomarkers of tumour fractionation sensitivity.
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Affiliation(s)
- N Somaiah
- The Institute of Cancer Research & The Royal Marsden NHS Foundation Trust, London, UK.
| | - K Rothkamm
- University Medical Center, Hamburg-Eppendorf, Germany
| | - J Yarnold
- The Institute of Cancer Research & The Royal Marsden NHS Foundation Trust, London, UK
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12
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Rint1 inactivation triggers genomic instability, ER stress and autophagy inhibition in the brain. Cell Death Differ 2015; 23:454-68. [PMID: 26383973 DOI: 10.1038/cdd.2015.113] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Revised: 06/30/2015] [Accepted: 07/08/2015] [Indexed: 11/08/2022] Open
Abstract
Endoplasmic reticulum (ER) stress, defective autophagy and genomic instability in the central nervous system are often associated with severe developmental defects and neurodegeneration. Here, we reveal the role played by Rint1 in these different biological pathways to ensure normal development of the central nervous system and to prevent neurodegeneration. We found that inactivation of Rint1 in neuroprogenitors led to death at birth. Depletion of Rint1 caused genomic instability due to chromosome fusion in dividing cells. Furthermore, Rint1 deletion in developing brain promotes the disruption of ER and Cis/Trans Golgi homeostasis in neurons, followed by ER-stress increase. Interestingly, Rint1 deficiency was also associated with the inhibition of the autophagosome clearance. Altogether, our findings highlight the crucial roles of Rint1 in vivo in genomic stability maintenance, as well as in prevention of ER stress and autophagy.
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Soni A, Siemann M, Pantelias GE, Iliakis G. Marked contribution of alternative end-joining to chromosome-translocation-formation by stochastically induced DNA double-strand-breaks in G2-phase human cells. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2015; 793:2-8. [PMID: 26520366 DOI: 10.1016/j.mrgentox.2015.07.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 07/01/2015] [Indexed: 01/15/2023]
Abstract
Ionizing radiation (IR) induces double strand breaks (DSBs) in cellular DNA, which if not repaired correctly can cause chromosome translocations leading to cell death or cancer. Incorrect joining of DNA ends generating chromosome translocations can be catalyzed either by the dominant DNA-PKcs-dependent, classical non-homologous end-joining (c-NHEJ), or by an alternative end-joining (alt-EJ) process, functioning as backup to abrogated c-NHEJ, or homologous recombination repair. Alt-EJ operates with slower kinetics as compared to c-NHEJ and generates larger alterations at the junctions; it is also considered crucial to chromosome translocation-formation. A recent report posits that this view only holds for rodent cells and that in human cells c-NHEJ is the main mechanism of chromosome translocation formation. Since this report uses designer nucleases that induce DSBs with unique characteristics in specific genomic locations and PCR to detect translocations, we revisit the issue using stochastically distributed DSBs induced in the human genome by IR during the G2-phase of the cell cycle. For visualization and analysis of chromosome translocations, which manifest as chromatid translocations in cells irradiated in G2, we employ classical cytogenetics. In wild-type cells, we observe a significant contribution of alt-EJ to translocation formation, as demonstrated by a yield-reduction after treatment with inhibitors of Parp, or of DNA ligases 1 and 3 (Lig1, Lig3). Notably, a nearly fourfold increase in translocation formation is seen in c-NHEJ mutants with defects in DNA ligase 4 (Lig4) that remain largely sensitive to inhibitors of Parp, and of Lig1/Lig3. We conclude that similar to rodent cells, chromosome translocation formation from randomly induced DSBs in human cells largely relies on alt-EJ. We discuss DSB localization in the genome, characteristics of the DSB and the cell cycle as potential causes of the divergent results generated with IR and designer nucleases.
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Affiliation(s)
- Aashish Soni
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, Essen, Germany
| | - Maria Siemann
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, Essen, Germany
| | - Gabriel E Pantelias
- Institute of Nuclear Technology and Radiation Protection, National Centre for Scientific Research "Demokritos,"Aghia Paraskevi Attikis, Athens, Greece
| | - George Iliakis
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, Essen, Germany.
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Cannan WJ, Tsang BP, Wallace SS, Pederson DS. Nucleosomes suppress the formation of double-strand DNA breaks during attempted base excision repair of clustered oxidative damages. J Biol Chem 2014; 289:19881-93. [PMID: 24891506 DOI: 10.1074/jbc.m114.571588] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Exposure to ionizing radiation can produce multiple, clustered oxidative lesions in DNA. The near simultaneous excision of nearby lesions in opposing DNA strands by the base excision repair (BER) enzymes can produce double-strand DNA breaks (DSBs). This attempted BER accounts for many of the potentially lethal or mutagenic DSBs that occur in vivo. To assess the impact of nucleosomes on the frequency and pattern of BER-dependent DSB formation, we incubated nucleosomes containing oxidative damages in opposing DNA strands with selected DNA glycosylases and human apurinic/apyrimidinic endonuclease 1. Overall, nucleosomes substantially suppressed DSB formation. However, the degree of suppression varied as a function of (i) the lesion type and DNA glycosylase tested, (ii) local sequence context and the stagger between opposing strand lesions, (iii) the helical orientation of oxidative lesions relative to the underlying histone octamer, and (iv) the distance between the lesion cluster and the nucleosome edge. In some instances the binding of a BER factor to one nucleosomal lesion appeared to facilitate binding to the opposing strand lesion. DSB formation did not invariably lead to nucleosome dissolution, and in some cases, free DNA ends resulting from DSB formation remained associated with the histone octamer. These observations explain how specific structural and dynamic properties of nucleosomes contribute to the suppression of BER-generated DSBs. These studies also suggest that most BER-generated DSBs will occur in linker DNA and in genomic regions associated with elevated rates of nucleosome turnover or remodeling.
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Affiliation(s)
- Wendy J Cannan
- From the Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont 05405
| | - Betty P Tsang
- From the Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont 05405
| | - Susan S Wallace
- From the Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont 05405
| | - David S Pederson
- From the Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont 05405
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15
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Grygoryev D, Dan C, Gauny S, Eckelmann B, Ohlrich AP, Connolly M, Lasarev M, Grossi G, Kronenberg A, Turker MS. Autosomal mutants of proton-exposed kidney cells display frequent loss of heterozygosity on nonselected chromosomes. Radiat Res 2014; 181:452-63. [PMID: 24758577 DOI: 10.1667/rr13654.1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
High-energy protons found in the space environment can induce mutations and cancer, which are inextricably linked. We hypothesized that some mutants isolated from proton-exposed kidneys arose through a genome-wide incident that causes loss of heterozygosity (LOH)-generating mutations on multiple chromosomes (termed here genomic LOH). To test this hypothesis, we examined 11 pairs of nonselected chromosomes for LOH events in mutant cells isolated from the kidneys of mice exposed to 4 or 5 Gy of 1 GeV protons. The mutant kidney cells were selected for loss of expression of the chromosome 8-encoded Aprt gene. Genomic LOH events were also assessed in Aprt mutants isolated from isogenic cultured kidney epithelial cells exposed to 5 Gy of protons in vitro. Control groups were spontaneous Aprt mutants and clones isolated without selection from the proton-exposed kidneys or cultures. The in vivo results showed significant increases in genomic LOH events in the Aprt mutants from proton-exposed kidneys when compared with spontaneous Aprt mutants and when compared with nonmutant (i.e., nonselected) clones from the proton-exposed kidneys. A bias for LOH events affecting chromosome 14 was observed in the proton-induced Aprt mutants, though LOH for this chromosome did not confer increased radiation resistance. Genomic LOH events were observed in Aprt mutants isolated from proton-exposed cultured kidney cells; however the incidence was fivefold lower than in Aprt mutants isolated from exposed intact kidneys, suggesting a more permissive environment in the intact organ and/or the evolution of kidney clones prior to their isolation from the tissue. We conclude that proton exposure creates a subset of viable cells with LOH events on multiple chromosomes, that these cells form and persist in vivo, and that they can be isolated from an intact tissue by selection for a mutation on a single chromosome.
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Affiliation(s)
- Dmytro Grygoryev
- a Center for Research on Occupational and Environmental Toxicology (CROET), Oregon Health & Science University, Portland, Oregon 97239
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16
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Cartwright IM, Genet MD, Fujimori A, Kato TA. Role of LET and chromatin structure on chromosomal inversion in CHO10B2 cells. Genome Integr 2014; 5:1. [PMID: 24467838 PMCID: PMC3917374 DOI: 10.1186/2041-9414-5-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Accepted: 01/21/2014] [Indexed: 11/25/2022] Open
Abstract
Background In this study we evaluated the effect of linear energy transfer (LET) and chromatin structure on the induction of chromosomal inversion. High LET radiation causes more complex DNA damage than low LET radiation; this “dirty” damage is more difficult to repair and may result in an increase in inversion formation. CHO10B2 cells synchronized in either G1 or M phase were exposed 0, 1, or 2 Gy of 5 mm Al and Cu filters at 200 kVp and 20 mA X-rays or 500 MeV/nucleon of initial energy and 200 keV/μ m Fe ion radiation. In order to increase the sensitivity of prior techniques used to study inversions, we modified the more traditional Giemsa plus fluorescence technique so that cells were only allowed to incorporate BrdU for a single cycle verses 2 cycles. The BrdU incorporated DNA strand was labeled using a BrdU antibody and an Alexa Fluor 488 probe. This modified technique allowed us to observe inversions smaller than 0.6 megabases (Mb). Results In this study we have shown that high LET radiation induces significantly more inversions in G1 cells than in M phase cells. Additionally, we have shown that the sizes of the induced inversions not only differ between Fe ion and X-rays, but also between G1 and M phase cells exposed to Fe ions. Conclusion We have effectively shown that both radiation quality and chromosome structure interact to alter not only the number of inversions induced, but also the size of the inversions.
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Affiliation(s)
| | | | | | - Takamitsu A Kato
- Department of Environmental and Radiological Health Sciences, Colorado State University, 1618 Campus Delivery, Fort Collins 80523, USA.
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Meenakshi C, Mohankumar MN. Synergistic effect of radon in blood cells of smokers – An in vitro study. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2013; 757:79-82. [DOI: 10.1016/j.mrgentox.2013.06.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2012] [Revised: 06/13/2013] [Accepted: 06/21/2013] [Indexed: 10/26/2022]
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18
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Sankaranarayanan K, Taleei R, Rahmanian S, Nikjoo H. Ionizing radiation and genetic risks. XVII. Formation mechanisms underlying naturally occurring DNA deletions in the human genome and their potential relevance for bridging the gap between induced DNA double-strand breaks and deletions in irradiated germ cells. Mutat Res 2013; 753:114-130. [PMID: 23948232 DOI: 10.1016/j.mrrev.2013.07.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Revised: 06/27/2013] [Accepted: 07/22/2013] [Indexed: 12/21/2022]
Abstract
While much is known about radiation-induced DNA double-strand breaks (DSBs) and their repair, the question of how deletions of different sizes arise as a result of the processing of DSBs by the cell's repair systems has not been fully answered. In order to bridge this gap between DSBs and deletions, we critically reviewed published data on mechanisms pertaining to: (a) repair of DNA DSBs (from basic studies in this area); (b) formation of naturally occurring structural variation (SV) - especially of deletions - in the human genome (from genomic studies) and (c) radiation-induced mutations and structural chromosomal aberrations in mammalian somatic cells (from radiation mutagenesis and radiation cytogenetic studies). The specific aim was to assess the relative importance of the postulated mechanisms in generating deletions in the human genome and examine whether empirical data on radiation-induced deletions in mouse germ cells are consistent with predictions of these mechanisms. The mechanisms include (a) NHEJ, a DSB repair process that does not require any homology and which functions in all stages of the cell cycle (and is of particular relevance in G0/G1); (b) MMEJ, also a DSB repair process but which requires microhomology and which presumably functions in all cell cycle stages; (c) NAHR, a recombination-based DSB repair mechanism which operates in prophase I of meiosis in germ cells; (d) MMBIR, a microhomology-mediated, replication-based mechanism which operates in the S phase of the cell cycle, and (e) strand slippage during replication (involved in the origin of small insertions and deletions (INDELs). Our analysis permits the inference that, between them, these five mechanisms can explain nearly all naturally occurring deletions of different sizes identified in the human genome, NAHR and MMBIR being potentially more versatile in this regard. With respect to radiation-induced deletions, the basic studies suggest that those arising as a result of the operation of NHEJ/MMEJ processes, as currently formulated, are expected to be relatively small. However, data on induced mutations in mouse spermatogonial stem cells (irradiation in G0/G1 phase of the cell cycle and DSB repair presumed to be via NHEJ predominantly) show that most are associated with deletions of different sizes, some in the megabase range. There is thus a 'discrepancy' between what the basic studies suggest and the empirical observations in mutagenesis studies. This discrepancy, however, is only an apparent but not a real one. It can be resolved by considering the issue of deletions in the broader context of and in conjunction with the organization of chromatin in chromosomes and nuclear architecture, the conceptual framework for which already exists in studies carried out during the past fifteen years or so. In this paper, we specifically hypothesize that repair of DSBs induced in chromatin loops may offer a basis to explain the induction of deletions of different sizes and suggest an approach to test the hypothesis. We emphasize that the bridging of the gap between induced DSB and resulting deletions of different sizes is critical for current efforts in computational modeling of genetic risks.
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Affiliation(s)
- Krishnaswami Sankaranarayanan
- Radiation Biophysics Group, Department of Oncology-Pathology, Karolinska Instituet, Box 260, Stockholm SE 17176, Sweden
| | - Reza Taleei
- Radiation Biophysics Group, Department of Oncology-Pathology, Karolinska Instituet, Box 260, Stockholm SE 17176, Sweden
| | - Shirin Rahmanian
- Radiation Biophysics Group, Department of Oncology-Pathology, Karolinska Instituet, Box 260, Stockholm SE 17176, Sweden
| | - Hooshang Nikjoo
- Radiation Biophysics Group, Department of Oncology-Pathology, Karolinska Instituet, Box 260, Stockholm SE 17176, Sweden.
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19
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Rübben A, Nordhoff O. A systems approach defining constraints of the genome architecture on lineage selection and evolvability during somatic cancer evolution. Biol Open 2012; 2:49-62. [PMID: 23336076 PMCID: PMC3545268 DOI: 10.1242/bio.20122543] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Accepted: 10/15/2012] [Indexed: 12/22/2022] Open
Abstract
Most clinically distinguishable malignant tumors are characterized by specific mutations, specific patterns of chromosomal rearrangements and a predominant mechanism of genetic instability but it remains unsolved whether modifications of cancer genomes can be explained solely by mutations and selection through the cancer microenvironment. It has been suggested that internal dynamics of genomic modifications as opposed to the external evolutionary forces have a significant and complex impact on Darwinian species evolution. A similar situation can be expected for somatic cancer evolution as molecular key mechanisms encountered in species evolution also constitute prevalent mutation mechanisms in human cancers. This assumption is developed into a systems approach of carcinogenesis which focuses on possible inner constraints of the genome architecture on lineage selection during somatic cancer evolution. The proposed systems approach can be considered an analogy to the concept of evolvability in species evolution. The principal hypothesis is that permissive or restrictive effects of the genome architecture on lineage selection during somatic cancer evolution exist and have a measurable impact. The systems approach postulates three classes of lineage selection effects of the genome architecture on somatic cancer evolution: i) effects mediated by changes of fitness of cells of cancer lineage, ii) effects mediated by changes of mutation probabilities and iii) effects mediated by changes of gene designation and physical and functional genome redundancy. Physical genome redundancy is the copy number of identical genetic sequences. Functional genome redundancy of a gene or a regulatory element is defined as the number of different genetic elements, regardless of copy number, coding for the same specific biological function within a cancer cell. Complex interactions of the genome architecture on lineage selection may be expected when modifications of the genome architecture have multiple and possibly opposed effects which manifest themselves at disparate times and progression stages. Dissection of putative mechanisms mediating constraints exerted by the genome architecture on somatic cancer evolution may provide an algorithm for understanding and predicting as well as modifying somatic cancer evolution in individual patients.
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Affiliation(s)
- Albert Rübben
- Independent Institute of Systems Sciences Aachen , 52064 Aachen , Germany ; Department of Dermatology, RWTH Aachen University , 52074 Aachen , Germany
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20
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Terzoudi GI, Hatzi VI, Donta-Bakoyianni C, Pantelias GE. Chromatin dynamics during cell cycle mediate conversion of DNA damage into chromatid breaks and affect formation of chromosomal aberrations: biological and clinical significance. Mutat Res 2011; 711:174-186. [PMID: 21185845 DOI: 10.1016/j.mrfmmm.2010.12.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2010] [Revised: 11/30/2010] [Accepted: 12/17/2010] [Indexed: 05/30/2023]
Abstract
The formation of diverse chromosomal aberrations following irradiation and the variability in radiosensitivity at different cell-cycle stages remain a long standing controversy, probably because most of the studies have focused on elucidating the enzymatic mechanisms involved using simple DNA substrates. Yet, recognition, processing and repair of DNA damage occur within the nucleoprotein complex of chromatin which is dynamic in nature, capable of rapid unfolding, disassembling, assembling and refolding. The present work reviews experimental work designed to investigate the impact of chromatin dynamics and chromosome conformation changes during cell-cycle in the formation of chromosomal aberrations. Using conventional cytogenetics and premature chromosome condensation to visualize interphase chromatin, the data presented support the hypothesis that chromatin dynamic changes during cell-cycle are important determinants in the conversion of sub-microscopic DNA lesions into chromatid breaks. Consequently, the type and yield of radiation-induced chromosomal aberrations at a given cell-cycle-stage depends on the combined effect of DNA repair processes and chromatin dynamics, which is cell-cycle-regulated and subject to up- or down-regulation following radiation exposure or genetic alterations. This new hypothesis is used to explain the variability in radiosensitivity observed at various cell-cycle-stages, among mutant cells and cells of different origin, or among different individuals, and to revisit unresolved issues and unanswered questions. In addition, it is used to better understand hypersensitivity of AT cells and to provide an improved predictive G2-assay for evaluating radiosensitivity at individual level. Finally, experimental data at single cell level obtained using hybrid cells suggest that the proposed hypothesis applies only to the irradiated component of the hybrid.
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Affiliation(s)
- Georgia I Terzoudi
- Institute of Radioisotopes and Radiodiagnostic Products, National Centre for Scientific Research "Demokritos", 15310 Ag. Paraskevi Attikis, Athens, Greece
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21
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Hada M, Wu H, Cucinotta FA. mBAND analysis for high- and low-LET radiation-induced chromosome aberrations: a review. Mutat Res 2011; 711:187-192. [PMID: 21232544 DOI: 10.1016/j.mrfmmm.2010.12.018] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2010] [Revised: 12/17/2010] [Accepted: 12/17/2010] [Indexed: 05/30/2023]
Abstract
During long-term space travel or cancer therapy, humans are exposed to high linear energy transfer (LET) energetic heavy ions. High-LET radiation is much more effective than low-LET radiation in causing various biological effects, including cell inactivation, genetic mutations, cataracts and cancer induction. Most of these biological endpoints are closely related to chromosomal damage, and cytogenetic damage can be utilized as a biomarker for radiation insults. Epidemiological data, mainly from survivors of the atomic bomb detonations in Japan, have enabled risk estimation from low-LET radiation exposures. The identification of a cytogenetic signature that distinguishes high- from low-LET exposure remains a long-term goal in radiobiology. Recently developed fluorescence in situ hybridization (FISH)-painting methodologies have revealed unique endpoints related to radiation quality. Heavy-ions induce a high fraction of complex-type exchanges, and possibly unique chromosome rearrangements. This review will concentrate on recent data obtained with multicolor banding in situ hybridization (mBAND) methods in mammalian cells exposed to low- and high-LET radiations. Chromosome analysis with mBAND technique allows detection of both inter- and intrachromosomal exchanges, and also distribution of the breakpoints of aberrations.
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Affiliation(s)
- Megumi Hada
- NASA Johnson Space Center, Houston, TX 77058, USA; Universities Space Research Association, Houston, TX 77058, USA.
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22
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Wang Q, Xu Y, Xie MJ, Yu ZY, Qin YY, Wang W, Zhu Z. X-irradiation reduces the proliferation of astrocytes by cell cycle arrest. Neurosci Lett 2011; 498:78-83. [PMID: 21557987 DOI: 10.1016/j.neulet.2011.04.067] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2011] [Revised: 04/25/2011] [Accepted: 04/27/2011] [Indexed: 11/18/2022]
Abstract
Reactive astrogliosis is one of the key components of the cellular response to CNS injury and is considered a major impediment to axonal regeneration. Our previous study demonstrated that cell cycle inhibition treatment can reduce astrocyte activation and proliferation in vivo. In this study, we examined whether reactive astrogliosis can be suppressed by X-irradiation in vitro by modulating cell cycle progression. X-irradiation with low dose (4 Gy) suppressed astrocyte proliferation as demonstrated by immunofluorescence staining with BrdU and Ki67 in monolayer astrocyte cultures and those in scratch-wound model. The proportions of BrdU (+) and Ki67 (+) cells at 12, 24, and 48 h after 4 Gy irradiation were significantly lower than those in control group. FACS analysis of monolayer astrocyte cultures showed that X-irradiation decreased the proportion of astrocytes in S phase at 12 and 24h after irradiation with a dose-dependent manner. Furthermore, after X-irradiation, higher levels of p53 were observed by western blot as compared to control astrocyte cultures. Taken together, these data support that X-irradiation can decrease astrogliosis via arresting the cell cycle progression, which might constitute an effective therapeutic intervention in diseases characterized by excessive proliferation of glial cells.
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Affiliation(s)
- Qi Wang
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, No. 1095 Jiefang Avenue, Wuhan 430030, China
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23
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Nagasawa H, Brogan JR, Peng Y, Little JB, Bedford JS. Some unsolved problems and unresolved issues in radiation cytogenetics: A review and new data on roles of homologous recombination and non-homologous end joining. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2010; 701:12-22. [DOI: 10.1016/j.mrgentox.2010.03.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2010] [Accepted: 03/09/2010] [Indexed: 12/14/2022]
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24
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Pantelias GE, Terzoudi GI. Functional cell-cycle chromatin conformation changes in the presence of DNA damage result into chromatid breaks: A new insight in the formation of radiation-induced chromosomal aberrations based on the direct observation of interphase chromatin. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2010; 701:27-37. [DOI: 10.1016/j.mrgentox.2010.04.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Accepted: 04/06/2010] [Indexed: 11/15/2022]
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25
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Sigounas G, Hairr JW, Cooke CD, Owen JR, Asch AS, Weidner DA, Wiley JE. Role of benzo[alpha]pyrene in generation of clustered DNA damage in human breast tissue. Free Radic Biol Med 2010; 49:77-87. [PMID: 20347033 DOI: 10.1016/j.freeradbiomed.2010.03.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2009] [Revised: 03/06/2010] [Accepted: 03/18/2010] [Indexed: 12/23/2022]
Abstract
Complex DNA damage may manifest in double-strand breaks (DSBs) and non-DSB, bistranded, oxidatively induced clustered DNA lesions (OCDLs). Although the carcinogen benzo[alpha]pyrene (B[alpha]P) has been shown to induce chromosomal aberrations and transformation of mammary cells, it is not known whether this compound engenders clustered DNA damage. Normal primary breast tissue-derived cells were treated with B[alpha]P, and the levels of DNA lesions, chromosomal aberrations, total antioxidant capacity (TAC), and reactive oxygen species (ROS) were determined. DNA from cells treated with 2 and 8 microM B[alpha]P exhibited increases of 3- and 4-fold in APE1 (p<0.001), 11- and 19-fold in Endo III (p<0.001), and 8- and 15-fold in hOGG1 (p<0.001) OCDLs, respectively, compared to the 0 microM B[alpha]P-treated (control) group. Mammary cells treated with 8 microM B[alpha]P produced 0.12 aberrations per cell (p<0.05) and there was a strong positive correlation (r=0.91) between the levels of OCDLs and those of chromosomal aberrations. Finally, TAC was decreased by 25% (p<0.02), whereas ROS production increased by 2-fold (p<0.02) in cells treated with 8 microM B[alpha]P compared to the control group. In conclusion, oxidatively induced clustered DNA damage mediated through differential expression of APE1, reduced TAC, and increased ROS may play a significant role in the chemically induced transformation of normal primary mammary cells.
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Affiliation(s)
- George Sigounas
- Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA.
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26
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Brehwens K, Staaf E, Haghdoost S, González AJ, Wojcik A. Cytogenetic damage in cells exposed to ionizing radiation under conditions of a changing dose rate. Radiat Res 2010; 173:283-9. [PMID: 20199213 DOI: 10.1667/rr2012.1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The current international paradigm on the biological effects of radiation is based mainly on the effects of dose with some consideration for the dose rate. No allowance has been made for the potential influence of a changing dose rate (second derivative of dose), and the biological effects of exposing cells to changing dose rates have never been analyzed. This paper provides evidence that radiation effects in cells may depend on temporal changes in the dose rate. In these experiments, cells were moved toward or away from an X-ray source. The speed of movement, the time of irradiation, and the temperature during exposure were controlled. Here we report the results of the first experiments with TK6 cells that were exposed at a constant dose rate, at an increasing dose rate, or at a decreasing dose rate. The average dose rate and the total dose were same for all samples. Micronuclei were scored as the end point. The results show that the level of cytogenetic damage was higher in cells exposed to a decreasing dose rate compared to both an increasing and a constant dose rate. This finding may suggest that the second derivative of dose may influence radiation risk estimates, and the results should trigger further studies on this issue.
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Affiliation(s)
- Karl Brehwens
- Centre for Radiation Protection Research, GMT Department, Stockholm University, Stockholm, Sweden
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27
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Abstract
PURPOSE Ionising radiation exposure gives rise to a variety of lesions in DNA that result in genetic instability and potentially tumourigenesis or cell death. Radiation extends its effects on DNA by direct interaction or by radiolysis of H(2)O that generates free radicals or aqueous electrons capable of interacting with and causing indirect damage to DNA. While the various lesions arising in DNA after radiation exposure can contribute to the mutagenising effects of this agent, the potentially most damaging lesion is the DNA double strand break (DSB) that contributes to genome instability and/or cell death. Thus in many cases failure to recognise and/or repair this lesion determines the radiosensitivity status of the cell. DNA repair mechanisms including homologous recombination (HR) and non-homologous end-joining (NHEJ) have evolved to protect cells against DNA DSB. Mutations in proteins that constitute these repair pathways are characterised by radiosensitivity and genome instability. Defects in a number of these proteins also give rise to genetic disorders that feature not only genetic instability but also immunodeficiency, cancer predisposition, neurodegeneration and other pathologies. CONCLUSIONS In the past 50 years our understanding of the cellular response to radiation damage has advanced enormously with insight being gained from a wide range of approaches extending from more basic early studies to the sophisticated approaches used today. In this review we discuss our current understanding of the impact of radiation on the cell and the organism gained from the array of past and present studies and attempt to provide an explanation for what it is that determines the response to radiation.
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Affiliation(s)
- Penny Jeggo
- Genome Damage and Stability Centre, Science Park Road, University of Sussex, Falmer, Brighton, East Sussex BN1 9RQ, UK.
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28
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Costes SV, Chiolo I, Pluth JM, Barcellos-Hoff MH, Jakob B. Spatiotemporal characterization of ionizing radiation induced DNA damage foci and their relation to chromatin organization. Mutat Res 2010; 704:78-87. [PMID: 20060491 DOI: 10.1016/j.mrrev.2009.12.006] [Citation(s) in RCA: 165] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2009] [Revised: 12/17/2009] [Accepted: 12/22/2009] [Indexed: 11/28/2022]
Abstract
DNA damage sensing proteins have been shown to localize to the sites of DNA double strand breaks (DSB) within seconds to minutes following ionizing radiation (IR) exposure, resulting in the formation of microscopically visible nuclear domains referred to as radiation-induced foci (RIF). This review characterizes the spatiotemporal properties of RIF at physiological doses, minutes to hours following exposure to ionizing radiation, and it proposes a model describing RIF formation and resolution as a function of radiation quality and chromatin territories. Discussion is limited to RIF formed by three interrelated proteins ATM (Ataxia telangiectasia mutated), 53BP1 (p53 binding protein 1) and gammaH2AX (phosphorylated variant histone H2AX), with an emphasis on the later. This review discusses the importance of not equating RIF with DSB in all situations and shows how dose and time dependence of RIF frequency is inconsistent with a one to one equivalence. Instead, we propose that RIF mark regions of the chromatin that would serve as scaffolds rigid enough to keep broken DNA from diffusing away, but open enough to allow the repair machinery to access the damage site. We review data indicating clear kinetic and physical differences between RIF emerging from dense and uncondensed regions of the nucleus. We suggest that persistent RIF observed days following exposure to ionizing radiation are nuclear marks of permanent rearrangement of the chromatin architecture. Such chromatin alterations may not always lead to growth arrest as cells have been shown to replicate these in progeny. Thus, heritable persistent RIF spanning over tens of Mbp may reflect persistent changes in the transcriptome of a large progeny of cells. Such model opens the door to a "non-DNA-centric view" of radiation-induced phenotypes.
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Affiliation(s)
- S V Costes
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
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Hamasaki K, Kusunoki Y, Nakashima E, Takahashi N, Nakachi K, Nakamura N, Kodama Y. Clonally expanded T lymphocytes from atomic bomb survivors in vitro show no evidence of cytogenetic instability. Radiat Res 2009; 172:234-43. [PMID: 19630528 DOI: 10.1667/rr1705.1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Abstract Genomic instability has been suggested as a mechanism by which exposure to ionizing radiation can lead to cancer in exposed humans. However, the data from human cells needed to support or refute this idea are limited. In our previous study on clonal lymphocyte populations carrying stable-type aberrations derived from A-bomb survivors, we found no increase in the frequency of sporadic additional aberrations among the clonal cell populations compared with the spontaneous frequency in vivo. That work has been extended by using multicolor FISH (mFISH) to quantify the various kinds of chromosome aberrations known to be indicative of genomic instability in cloned T lymphocytes after they were expanded in culture for 25 population doublings. The blood T cells used were obtained from each of two high-dose-exposed survivors (>1 Gy) and two control subjects, and a total of 66 clonal populations (36 from exposed and 30 from control individuals) were established. For each clone, 100 metaphases were examined. In the case of exposed lymphocytes, a total of 39 additional de novo stable, exchange-type aberrations [translocation (t) + derivative chromosome (der)] were found among 3600 cells (1.1%); the corresponding value in the control group was 0.6% (17/3000). Although the ratio (39/3600) obtained from the exposed cases was greater than that of the controls (17/3000), the difference was not statistically significant (P = 0.101). A similar lack of statistical difference was found for the total of all structural chromosome alterations including t, der, dicentrics, duplications, deletions and fragments (P = 0.142). Thus there was no clear evidence suggesting the presence of chromosome instabilities among the clonally expanded lymphocytes in vitro from A-bomb survivors.
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Affiliation(s)
- K Hamasaki
- Departments of Radiobiology and Molecular Epidemiology, Radiation Effects Research Foundation, Minami-ku, Hiroshima, 732-0815, Japan
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30
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Morciano P, Carrisi C, Capobianco L, Mannini L, Burgio G, Cestra G, De Benedetto GE, Corona DFV, Musio A, Cenci G. A conserved role for the mitochondrial citrate transporter Sea/SLC25A1 in the maintenance of chromosome integrity. Hum Mol Genet 2009; 18:4180-8. [PMID: 19654186 DOI: 10.1093/hmg/ddp370] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Histone acetylation plays essential roles in cell cycle progression, DNA repair, gene expression and silencing. Although the knowledge regarding the roles of acetylation of histone lysine residues is rapidly growing, very little is known about the biochemical pathways providing the nucleus with metabolites necessary for physiological chromatin acetylation. Here, we show that mutations in the scheggia (sea)-encoded Sea protein, the Drosophila ortholog of the human mitochondrial citrate carrier Solute carrier 25 A1 (SLC25A1), impair citrate transport from mitochondria to the cytosol. Interestingly, inhibition of sea expression results in extensive chromosome breakage in mitotic cells and induces an ATR-dependent cell cycle arrest associated with a dramatic reduction of global histone acetylation. Notably, loss of SLC25A1 in short interfering RNA (siRNA)-treated human primary fibroblasts also leads to chromosome breaks and histone acetylation defects, suggesting an evolutionary conserved role for Sea/SLC25A1 in the regulation of chromosome integrity. This study therefore provides an intriguing and unexpected link between intermediary metabolism and epigenetic control of genome stability.
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Affiliation(s)
- Patrizia Morciano
- Dipartimento di Biologia di Base ed Applicata, Università dell'Aquila, 67010 L'Aquila, Italy
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Kato TA, Okayasu R, Bedford JS. Signatures of DNA double strand breaks produced in irradiated G1 and G2 cells persist into mitosis. J Cell Physiol 2009; 219:760-5. [DOI: 10.1002/jcp.21726] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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Cytogenetic study of Ascaris trypsin inhibitor in cultured human lymphocytes with metabolic activation. J Genet 2009; 88:69-75. [PMID: 19417546 DOI: 10.1007/s12041-009-0009-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The trypsin inhibitor (ATI) isolated from gastrointestinal nematode Ascaris suum was tested in vitro for induction of chromosome aberrations and sister chromatid exchanges (SCE). Genotoxicity assessment of purified ATI was carried out on metaphase plates received from peripheral blood lymphocyte macroculture (48 h test of structural chromosome aberrations and 72 h test of SCE) with exogenous metabolic activation. ATI was tested in dose of 25, 50 and 100 microg per ml of culture. Kinetics of cell divisions were determined by the replication index (RI). The mitotic index (MI) was expressed as a number of metaphases per 1000 nuclei analysed. Analysis of chromosome aberrations showed that higher doses of ATI (50 and 100 microg/ml) significantly increased the frequency of chromosome aberrations (mainly of chromatid gaps and breaks) compared to the negative control. All concentrations of ATI caused a statistically significant reduction in the MI and RI. In comparison with the negative control, a significant increase in the SCE frequency was observed in all applied doses of ATI. Thus, in the presence of S9 activation, the Ascaris trypsin inhibitor showed potential clastogenic activity and inhibition of the dynamics of lymphocyte divisions.
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Sasaki MS. Advances in the biophysical and molecular bases of radiation cytogenetics. Int J Radiat Biol 2009; 85:26-47. [PMID: 19205983 DOI: 10.1080/09553000802641185] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
PURPOSE For more than 70 years radiation cytogenetics has continued to be a topic of major concern in relation to the action of radiation on living cells. To date, diverse cytogenetic findings have developed into orderly, quantitative interpretations and have stimulated numerous biophysical models. However, it is generally agreed that any one of the models used alone is still unable to explain all aspects of the observed chromosomal effects. In this review, a large number of radiation-induced chromosome aberration findings from the literature are reassessed with special attention given to the reaction kinetics and the relevant molecular processes. CONCLUSION It is now clear that DNA double-strand breaks (DSB) are an integral component of radiation-induced chromosome aberration. At the nexus of the maintenance of genome integrity, cells are equipped with excellent systems to repair DSB, notably non-homologous end-joining (NHEJ) and homologous recombination repair (HRR). These repair mechanisms are strictly regulated along with the DNA turnover cycle. NHEJ functions in all phases of the cell cycle, whereas HRR has a supplementary role specifically in S/G2 phase, where homologous DNA sequences are available in close proximity. The repair pathways are further regulated by a complex nuclear dynamism, where DSB are sensed and large numbers of repair proteins are recruited and assembled to form a repair complex involving multiple DSB. Considering such DSB repair dynamism, radiation-induced chromosome aberrations could be well understood as DSB-DSB pairwise interactions associated with the NHEJ pathway in all phases of the cell cycle and misrepair of a single DSB associated with the complementary HRR pathway in late S/G2 phase.
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Affiliation(s)
- M S Sasaki
- Radiation Biology Center, Kyoto University, Yoshida-konoecho, Sakyo-ku, Kyoto, Japan.
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Bignold L. Mechanisms of clastogen-induced chromosomal aberrations: A critical review and description of a model based on failures of tethering of DNA strand ends to strand-breaking enzymes. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2009; 681:271-298. [DOI: 10.1016/j.mrrev.2008.11.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2008] [Revised: 11/26/2008] [Accepted: 11/26/2008] [Indexed: 01/15/2023]
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Chaudhry MA. Real-Time PCR Analysis of Micro-RNA Expression in Ionizing Radiation-Treated Cells. Cancer Biother Radiopharm 2009; 24:49-56. [DOI: 10.1089/cbr.2008.0513] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Affiliation(s)
- M. Ahmad Chaudhry
- Department of Medical Laboratory and Radiation Sciences, University of Vermont, Burlington, VT
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Chaudhry MA. Biomarkers for human radiation exposure. J Biomed Sci 2008; 15:557-63. [DOI: 10.1007/s11373-008-9253-z] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2008] [Accepted: 03/12/2008] [Indexed: 02/01/2023] Open
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Wilson DM. Processing of nonconventional DNA strand break ends. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2007; 48:772-782. [PMID: 17948279 DOI: 10.1002/em.20346] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Single-strand breaks (SSBs) are one of the most common forms of genetic damage, arising from attack of DNA by reactive oxygen species or as intended or inadvertent products of normal cellular DNA metabolic events. Recent evidence linking defects in the enzymatic processing of nonconventional DNA SSBs, i.e., lesions incompatible with polymerase or ligase reactions, with inherited neurodegenerative disorders, reveals the importance of SSB repair in disease manifestation. I review herein the major eukaryotic enzymes (with an emphasis on the human proteins) responsible for the "clean-up" of DNA breaks harboring 3'- or 5'-blocking termini, and the cellular and disease ramifications of unrepaired SSB damage.
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Affiliation(s)
- David M Wilson
- Laboratory of Molecular Gerontology, National Institute on Aging, NIH, Baltimore, MD 21224, USA.
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Distinctive differences in DNA double-strand break repair between normal urothelial and urothelial carcinoma cells. Mutat Res 2007; 638:56-65. [PMID: 17928011 DOI: 10.1016/j.mrfmmm.2007.08.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2007] [Revised: 08/24/2007] [Accepted: 08/29/2007] [Indexed: 01/10/2023]
Abstract
Several lines of evidence suggest that defective repair of DNA double-strand breaks (DSB) contributes to genomic instability in human cancers, including urothelial carcinoma. In particular, extracts from urothelial cancers have been reported to repair DSBs preferentially by microhomology-mediated end-joining (MMEJ), considered as more error-prone than canonical non-homologous end-joining (NHEJ) predominating in normal urothelial cell extracts. However, it is not clear whether such differences are relevant to intact cells. We therefore transfected plasmids digested with different restriction enzymes to yield incompatible ends (blunt, 5'-protruding or 3'-protruding) into urothelial carcinoma cell lines or normal urothelial cells and characterized the recovered circular plasmids. All cells competently repaired DSBs in a standard cloning vector plasmid, processing 5'- as well as 3'-protruding ends. No significant differences in the extent of processing were detected and the junctions presented short microhomologies indicative of canonical NHEJ. However, dramatic and distinctive differences between normal and cancerous urothelial cells were seen in two different experiments. First, cancer cell lines processed a significantly higher fraction of plasmids cut with a single restriction enzyme that could have been repaired by direct ligation than normal cells. Secondly, for the repair of a large plasmid with incompatible ends containing a large fragment of human genomic DNA, normal cells used almost exclusively MMEJ exploiting a microhomology with the 3'-end of the break, whereas cancer cell lines often processed DNA despite suitable microhomologies. DNA repair of the small or large plasmid was almost abolished by siRNA knockdown of Ku70. These findings strongly suggest that urothelial carcinoma cells lack control mechanisms preventing overprocessing during NHEJ repair. This may account for previous findings that urothelial cancers contain unusually large chromosomal deletions. Moreover, in contrast to prevailing interpretations, our observations suggest that MMEJ, despite its error-proneness, in some instances may act as a failsafe mechanism against overprocessing during NHEJ.
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Kato TA, Wilson PF, Nagasawa H, Fitzek MM, Weil MM, Little JB, Bedford JS. A defect in DNA double strand break processing in cells from unaffected parents of retinoblastoma patients and other apparently normal humans. DNA Repair (Amst) 2007; 6:818-29. [PMID: 17339135 DOI: 10.1016/j.dnarep.2007.01.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2006] [Revised: 01/16/2007] [Accepted: 01/22/2007] [Indexed: 12/15/2022]
Abstract
Cells from unaffected parents of retinoblastoma (RB) patients were previously shown to be hypersensitive to radiation induced G(1) arrest and cell killing [1]. The hypersensitivity was similar to that reported for cells from ATM heterozygotes. The latter was consistent with a mild DNA DSB rejoining defect which we demonstrated using a gamma-H2AX focus assay after low dose-rate (LDR) irradiation of non-cycling G(0) cells [2,3]. Since neither parent carried the mutant RB allele of the RB heterozygous probands, these results suggested the possibility of an enhanced germline mutation rate, perhaps resulting from some mild defect in genome maintenance. We therefore examined levels of gamma-H2AX foci for cells from these RB parents in this G(0) LDR assay, which reflects the non-homologous end joining (NHEJ) capacity of cells and in a G(2)/M assay, which reflects additional contributions from other G(2)-related damage processing systems. For several of the cell strains parallel radiosensitivity comparisons were made for cell killing and for G(2) chromosomal radiosensitivities. G(0) cells from the RB parents were clearly hypersensitive both in the LDR gamma-H2AX assay, and for cell killing. In addition, cultured fibroblasts from 6 of 15 apparently normal individuals in this study (and one of six in a previous study) were also hypersensitive in the same assays. In the G(2)/M gamma-H2AX assay, the relative sensitivities were similar to those seen in the low dose-rate G(0) assay and tracked with chromosomal radiosensitivity, but some differences were observed.
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Affiliation(s)
- Takamitsu A Kato
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO 80523, United States
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