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Poignant F, Pariset E, Plante I, Ponomarev AL, Evain T, Viger L, Slaba TC, Blattnig SR, Costes SV. DNA break clustering as a predictor of cell death across various radiation qualities: influence of cell size, cell asymmetry, and beam orientation. Integr Biol (Camb) 2024; 16:zyae015. [PMID: 39299711 DOI: 10.1093/intbio/zyae015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Revised: 08/23/2024] [Indexed: 09/22/2024]
Abstract
Cosmic radiation, composed of high charge and energy (HZE) particles, causes cellular DNA damage that can result in cell death or mutation that can evolve into cancer. In this work, a cell death model is applied to several cell lines exposed to HZE ions spanning a broad range of linear energy transfer (LET) values. We hypothesize that chromatin movement leads to the clustering of multiple double strand breaks (DSB) within one radiation-induced foci (RIF). The survival probability of a cell population is determined by averaging the survival probabilities of individual cells, which is function of the number of pairwise DSB interactions within RIF. The simulation code RITCARD was used to compute DSB. Two clustering approaches were applied to determine the number of RIF per cell. RITCARD outputs were combined with experimental data from four normal human cell lines to derive the model parameters and expand its predictions in response to ions with LET ranging from ~0.2 keV/μm to ~3000 keV/μm. Spherical and ellipsoidal nuclear shapes and two ion beam orientations were modeled to assess the impact of geometrical properties on cell death. The calculated average number of RIF per cell reproduces the saturation trend for high doses and high-LET values that is usually experimentally observed. The cell survival model generates the recognizable bell shape of LET dependence for the relative biological effectiveness (RBE). At low LET, smaller nuclei have lower survival due to increased DNA density and DSB clustering. At high LET, nuclei with a smaller irradiation area-either because of a smaller size or a change in beam orientation-have a higher survival rate due to a change in the distribution of DSB/RIF per cell. If confirmed experimentally, the geometric characteristics of cells would become a significant factor in predicting radiation-induced biological effects. Insight Box: High-charge and energy (HZE) ions are characterized by dense linear energy transfer (LET) that induce unique spatial distributions of DNA damage in cell nuclei that result in a greater biological effect than sparsely ionizing radiation like X-rays. HZE ions are a prominent component of galactic cosmic ray exposure during human spaceflight and specific ions are being used for radiotherapy. Here, we model DNA damage clustering at sub-micrometer scale to predict cell survival. The model is in good agreement with experimental data for a broad range of LET. Notably, the model indicates that nuclear geometry and ion beam orientation affect DNA damage clustering, which reveals their possible role in mediating cell radiosensitivity.
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Affiliation(s)
- Floriane Poignant
- Analytical Mechanics Associates Inc., 21 Enterprise Parkway, Hampton, VA 23666, United States
| | - Eloise Pariset
- NASA Ames Research Center, MS:288/2, Mountain View, CA 94035, United States
- Universities Space Research Association, 615 National Avenue, Mountain View, CA 94043, United States
| | - Ianik Plante
- KBR, 2400 NASA Parkway, Houston, TX 77058, United States
| | | | - Trevor Evain
- Life Sciences Division, Lawrence Berkeley National Laboratory, 717 Potter Street, Berkeley, CA 94720, United States
| | - Louise Viger
- Life Sciences Division, Lawrence Berkeley National Laboratory, 717 Potter Street, Berkeley, CA 94720, United States
| | - Tony C Slaba
- NASA Langley Research Center, 1 Nasa Drive, Hampton, VA 23666, United States
| | - Steve R Blattnig
- NASA Langley Research Center, 1 Nasa Drive, Hampton, VA 23666, United States
| | - Sylvain V Costes
- NASA Ames Research Center, MS:288/2, Mountain View, CA 94035, United States
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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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Liang W, Wang S, Wang H, Li X, Meng Q, Zhao Y, Zheng C. When 3D genome technology meets viral infection, including SARS-CoV-2. J Med Virol 2022; 94:5627-5639. [PMID: 35916043 PMCID: PMC9538846 DOI: 10.1002/jmv.28040] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 07/09/2022] [Accepted: 07/30/2022] [Indexed: 01/06/2023]
Abstract
Mammalian chromosomes undergo varying degrees of compression to form three-dimensional genome structures. These three-dimensional structures undergo dynamic and precise chromatin interactions to achieve precise spatial and temporal regulation of gene expression. Most eukaryotic DNA viruses can invade their genomes into the nucleus. However, it is still poorly understood how the viral genome is precisely positioned after entering the host cell nucleus to find the most suitable location and whether it can specifically interact with the host genome to hijack the host transcriptional factories or even integrate into the host genome to complete its transcription and replication rapidly. Chromosome conformation capture technology can reveal long-range chromatin interactions between different chromosomal sites in the nucleus, potentially providing a reference for viral DNA-host chromatin interactions. This review summarized the research progress on the three-dimensional interaction between virus and host genome and the impact of virus integration into the host genome on gene transcription regulation, aiming to provide new insights into chromatin interaction and viral gene transcription regulation, laying the foundation for the treatment of infectious diseases.
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Affiliation(s)
- Weizheng Liang
- Central LaboratoryThe First Affiliated Hospital of Hebei North UniversityZhangjiakouChina
- Department of Immunology, School of Basic Medical SciencesFujian Medical UniversityFuzhouChina
| | - Shuangqing Wang
- Department of NeurologyShenzhen University General Hospital, Shenzhen UniversityShenzhen, Guangdong ProvinceChina
| | - Hao Wang
- Department of Obstetrics and GynecologyShenzhen University General HospitalShenzhen, GuangdongChina
| | - Xiushen Li
- Department of Obstetrics and GynecologyShenzhen University General HospitalShenzhen, GuangdongChina
- Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, School of Biomedical EngineeringShenzhen University Health Science CenterShenzhen, GuangdongChina
- Shenzhen Key LaboratoryShenzhen University General HospitalShenzhen, GuangdongChina
| | - Qingxue Meng
- Central LaboratoryThe First Affiliated Hospital of Hebei North UniversityZhangjiakouChina
| | - Yan Zhao
- Department of Mathematics and Computer ScienceFree University BerlinBerlinGermany
| | - Chunfu Zheng
- Department of Immunology, School of Basic Medical SciencesFujian Medical UniversityFuzhouChina
- Department of Microbiology, Immunology and Infectious DiseasesUniversity of CalgaryCalgaryAlbertaCanada
- The State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock, School of Life SciencesInner Mongolia UniversityHohhotChina
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Fleck K, Raj R, Erceg J. The 3D genome landscape: Diverse chromosomal interactions and their functional implications. Front Cell Dev Biol 2022; 10:968145. [PMID: 36036013 PMCID: PMC9402908 DOI: 10.3389/fcell.2022.968145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Accepted: 07/19/2022] [Indexed: 11/13/2022] Open
Abstract
Genome organization includes contacts both within a single chromosome and between distinct chromosomes. Thus, regulatory organization in the nucleus may include interplay of these two types of chromosomal interactions with genome activity. Emerging advances in omics and single-cell imaging technologies have allowed new insights into chromosomal contacts, including those of homologs and sister chromatids, and their significance to genome function. In this review, we highlight recent studies in this field and discuss their impact on understanding the principles of chromosome organization and associated functional implications in diverse cellular processes. Specifically, we describe the contributions of intra-chromosomal, inter-homolog, and inter-sister chromatid contacts to genome organization and gene expression.
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Affiliation(s)
- Katherine Fleck
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, United States
| | - Romir Raj
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, United States
| | - Jelena Erceg
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, United States
- Institute for Systems Genomics, University of Connecticut, Storrs, CT, United States
- Department of Genetics and Genome Sciences, University of Connecticut Health Center, Farmington, CT, United States
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Chromosome Folding Promotes Intrachromosomal Aberrations under Radiation- and Nuclease-Induced DNA Breakage. Int J Mol Sci 2021; 22:ijms222212186. [PMID: 34830065 PMCID: PMC8618582 DOI: 10.3390/ijms222212186] [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: 10/05/2021] [Revised: 11/04/2021] [Accepted: 11/06/2021] [Indexed: 11/19/2022] Open
Abstract
The long-standing question in radiation and cancer biology is how principles of chromosome organization impact the formation of chromosomal aberrations (CAs). To address this issue, we developed a physical modeling approach and analyzed high-throughput genomic data from chromosome conformation capture (Hi-C) and translocation sequencing (HTGTS) methods. Combining modeling of chromosome structure and of chromosomal aberrations induced by ionizing radiation (IR) and nuclease we made predictions which quantitatively correlated with key experimental findings in mouse chromosomes: chromosome contact maps, high frequency of cis-translocation breakpoints far outside of the site of nuclease-induced DNA double-strand breaks (DSBs), the distinct shape of breakpoint distribution in chromosomes with different 3D organizations. These correlations support the heteropolymer globule principle of chromosome organization in G1-arrested pro-B mouse cells. The joint analysis of Hi-C, HTGTS and physical modeling data offers mechanistic insight into how chromosome structure heterogeneity, globular folding and lesion dynamics drive IR-recurrent CAs. The results provide the biophysical and computational basis for the analysis of chromosome aberration landscape under IR and nuclease-induced DSBs.
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7
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Viscariello N, Greer MD, Parvathaneni U, Liao JJ, Laramore GE, Stewart RD. Comparisons of 3-Dimensional Conformal and Intensity-Modulated Neutron Therapy for Head and Neck Cancers. Int J Part Ther 2021; 8:51-61. [PMID: 34722811 PMCID: PMC8489487 DOI: 10.14338/ijpt-20-00059.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 03/03/2021] [Indexed: 11/21/2022] Open
Abstract
PURPOSE Neutron therapy is a high linear energy transfer modality that is useful for the treatment of radioresistant head and neck (H&N) cancers. It has been limited to 3-dimensioanal conformal-based fast-neutron therapy (3DCNT), but recent technical advances have enabled the clinical implementation of intensity-modulated neutron therapy (IMNT). This study evaluated the comparative dosimetry of IMNT and 3DCNT plans for the treatment of H&N cancers. MATERIALS AND METHODS Seven H&N IMNT plans were retrospectively created for patients previously treated with 3DCNT at the University of Washington (Seattle). A custom RayStation model with neutron-specific scattering kernels was used for inverse planning. Organ-at-risk (OAR) objectives from the original 3DCNT plan were initially used and were then systematically reduced to investigate the feasibility of improving a therapeutic ratio, defined as the ratio of the mean tumor to OAR dose. The IMNT and 3DCNT plan quality was evaluated using the therapeutic ratio, isodose contours, and dose volume histograms. RESULTS When compared with the 3DCNT plans, IMNT reduces the OAR dose for the equivalent tumor coverage. Moreover, IMNT is most advantageous for OARs in close spatial proximity to the target. For the 7 patients with H&N cancers examined, the therapeutic ratio for IMNT increased by an average of 56% when compared with the 3DCNT. The maximum OAR dose was reduced by an average of 20.5% and 20.7% for the spinal cord and temporal lobe, respectively. The mean dose to the larynx decreased by an average of 80%. CONCLUSION The IMNT significantly decreases the OAR doses compared with 3DCNT and provides comparable tumor coverage. Improvements in the therapeutic ratio with IMNT are especially significant for dose-limiting OARs near tumor targets. Moreover, IMNT provides superior sparing of healthy tissues and creates significant new opportunities to improve the care of patients with H&N cancers treated with neutron therapy.
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Affiliation(s)
- Natalie Viscariello
- Department of Radiation Oncology, University of Washington, Seattle, WA, USA
| | - Matthew D. Greer
- Department of Radiation Oncology, University of Washington, Seattle, WA, USA
| | | | - Jay J. Liao
- Department of Radiation Oncology, University of Washington, Seattle, WA, USA
| | - George E. Laramore
- Department of Radiation Oncology, University of Washington, Seattle, WA, USA
| | - Robert D. Stewart
- Department of Radiation Oncology, University of Washington, Seattle, WA, USA
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8
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McMahon SJ, Prise KM. A Mechanistic DNA Repair and Survival Model (Medras): Applications to Intrinsic Radiosensitivity, Relative Biological Effectiveness and Dose-Rate. Front Oncol 2021; 11:689112. [PMID: 34268120 PMCID: PMC8276175 DOI: 10.3389/fonc.2021.689112] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 05/31/2021] [Indexed: 01/04/2023] Open
Abstract
Variations in the intrinsic radiosensitivity of different cells to ionizing radiation is now widely believed to be a significant driver in differences in response to radiotherapy. While the mechanisms of radiosensitivity have been extensively studied in the laboratory, there are a lack of models which integrate this knowledge into a predictive framework. This paper presents an overview of the Medras model, which has been developed to provide a mechanistic framework in which different radiation responses can be modelled and individual responses predicted. This model simulates the repair of radiation-induced DNA damage, incorporating the overall kinetics of repair and its fidelity, to predict a range of biological endpoints including residual DNA damage, mutation, chromosome aberration, and cell death. Validation of this model against a range of exposure types is presented, including considerations of varying radiation qualities and dose-rates. This approach has the potential to inform new tools to deliver mechanistic predictions of radiation sensitivity, and support future developments in treatment personalization.
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Affiliation(s)
- Stephen Joseph McMahon
- Patrick G Johnston Centre for Cancer Research, Queen’s University Belfast, Belfast, United Kingdom
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9
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Guin K, Chen Y, Mishra R, Muzaki SRBM, Thimmappa BC, O'Brien CE, Butler G, Sanyal A, Sanyal K. Spatial inter-centromeric interactions facilitated the emergence of evolutionary new centromeres. eLife 2020; 9:e58556. [PMID: 32469306 PMCID: PMC7292649 DOI: 10.7554/elife.58556] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 05/22/2020] [Indexed: 12/12/2022] Open
Abstract
Centromeres of Candida albicans form on unique and different DNA sequences but a closely related species, Candida tropicalis, possesses homogenized inverted repeat (HIR)-associated centromeres. To investigate the mechanism of centromere type transition, we improved the fragmented genome assembly and constructed a chromosome-level genome assembly of C. tropicalis by employing PacBio sequencing, chromosome conformation capture sequencing (3C-seq), chromoblot, and genetic analysis of engineered aneuploid strains. Further, we analyzed the 3D genome organization using 3C-seq data, which revealed spatial proximity among the centromeres as well as telomeres of seven chromosomes in C. tropicalis. Intriguingly, we observed evidence of inter-centromeric translocations in the common ancestor of C. albicans and C. tropicalis. Identification of putative centromeres in closely related Candida sojae, Candida viswanathii and Candida parapsilosis indicates loss of ancestral HIR-associated centromeres and establishment of evolutionary new centromeres (ENCs) in C. albicans. We propose that spatial proximity of the homologous centromere DNA sequences facilitated karyotype rearrangements and centromere type transitions in human pathogenic yeasts of the CUG-Ser1 clade.
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Affiliation(s)
- Krishnendu Guin
- Molecular Mycology Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific ResearchBangaloreIndia
| | - Yao Chen
- School of Biological Sciences, Nanyang Technological UniversitySingaporeSingapore
| | - Radha Mishra
- Molecular Mycology Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific ResearchBangaloreIndia
| | | | - Bhagya C Thimmappa
- Molecular Mycology Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific ResearchBangaloreIndia
| | - Caoimhe E O'Brien
- School Of Biomolecular & Biomed Science, Conway Institute of Biomolecular and Biomedical Research, University College DublinDublinIreland
| | - Geraldine Butler
- School Of Biomolecular & Biomed Science, Conway Institute of Biomolecular and Biomedical Research, University College DublinDublinIreland
| | - Amartya Sanyal
- School of Biological Sciences, Nanyang Technological UniversitySingaporeSingapore
| | - Kaustuv Sanyal
- Molecular Mycology Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific ResearchBangaloreIndia
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10
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Ionizing Radiation and Complex DNA Damage: Quantifying the Radiobiological Damage Using Monte Carlo Simulations. Cancers (Basel) 2020; 12:cancers12040799. [PMID: 32225023 PMCID: PMC7226293 DOI: 10.3390/cancers12040799] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 03/23/2020] [Accepted: 03/25/2020] [Indexed: 02/07/2023] Open
Abstract
Ionizing radiation is a common tool in medical procedures. Monte Carlo (MC) techniques are widely used when dosimetry is the matter of investigation. The scientific community has invested, over the last 20 years, a lot of effort into improving the knowledge of radiation biology. The present article aims to summarize the understanding of the field of DNA damage response (DDR) to ionizing radiation by providing an overview on MC simulation studies that try to explain several aspects of radiation biology. The need for accurate techniques for the quantification of DNA damage is crucial, as it becomes a clinical need to evaluate the outcome of various applications including both low- and high-energy radiation medical procedures. Understanding DNA repair processes would improve radiation therapy procedures. Monte Carlo simulations are a promising tool in radiobiology studies, as there are clear prospects for more advanced tools that could be used in multidisciplinary studies, in the fields of physics, medicine, biology and chemistry. Still, lot of effort is needed to evolve MC simulation tools and apply them in multiscale studies starting from small DNA segments and reaching a population of cells.
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11
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Hill MA. Radiation Track Structure: How the Spatial Distribution of Energy Deposition Drives Biological Response. Clin Oncol (R Coll Radiol) 2020; 32:75-83. [PMID: 31511190 DOI: 10.1016/j.clon.2019.08.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 07/04/2019] [Accepted: 07/08/2019] [Indexed: 12/22/2022]
Abstract
Ionising radiation is incredibly effective at causing biological effects. This is due to the unique way energy is deposited along highly structured tracks of ionisation and excitation events, which results in correlation with sites of DNA damage from the nanometre to the micrometre scale. Correlation of these events along the track on the nanometre scale results in clustered damage, which not only results in the formation of DNA double-strand breaks (DSB), but also more difficult to repair complex DSB, which include additional damage within a few base pairs. The track structure varies significantly with radiation quality and the increase in relative biological effectiveness observed with increasing linear energy transfer in part corresponds to an increase in the probability and complexity of clustered DNA damage produced. Likewise, correlation over larger scales, associated with packing of DNA and associated chromosomes within the cell nucleus, can also have a major impact on the biological response. The proximity of the correlated damage along the track increases the probability of miss-repair through pairwise interactions resulting in an increase in probability and complexity of DNA fragments/deletions, mutations and chromosomal rearrangements. Understanding the mechanisms underlying the biological effectiveness of ionising radiation can provide an important insight into ways of increasing the efficacy of radiotherapy, as well as the risks associated with exposure. This requires a multi-scale approach for modelling, not only considering the physics of the track structure from the millimetre scale down to the nanometre scale, but also the structural packing of the DNA within the nucleus, the resulting chemistry in the context of the highly reactive environment of the nucleus, together with the subsequent biological response.
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Affiliation(s)
- M A Hill
- MRC Oxford Institute for Radiation Oncology, University of Oxford, Gray Laboratories, Oxford, UK.
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12
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Rosin LF, Crocker O, Isenhart RL, Nguyen SC, Xu Z, Joyce EF. Chromosome territory formation attenuates the translocation potential of cells. eLife 2019; 8:49553. [PMID: 31682226 PMCID: PMC6855801 DOI: 10.7554/elife.49553] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 11/02/2019] [Indexed: 12/11/2022] Open
Abstract
The formation and spatial arrangement of chromosome territories (CTs) in interphase has been posited to influence the outcome and frequency of genomic translocations. This is supported by correlations between the frequency of inter-chromosomal contacts and translocation events in myriad systems. However, it remains unclear if CT formation itself influences the translocation potential of cells. We address this question in Drosophila cells by modulating the level of Condensin II, which regulates CT organization. Using whole-chromosome Oligopaints to identify genomic rearrangements, we find that increased contact frequencies between chromosomes due to Condensin II knockdown leads to an increased propensity to form translocations following DNA damage. Moreover, Condensin II over-expression is sufficient to drive spatial separation of CTs and attenuate the translocation potential of cells. Together, these results provide the first causal evidence that proper CT formation can protect the genome from potentially deleterious translocations in the presence of DNA damage.
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Affiliation(s)
- Leah F Rosin
- Department of Genetics, Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States
| | - Olivia Crocker
- Department of Genetics, Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States
| | - Randi L Isenhart
- Department of Genetics, Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States
| | - Son C Nguyen
- Department of Genetics, Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States
| | - Zhuxuan Xu
- Department of Genetics, Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States
| | - Eric F Joyce
- Department of Genetics, Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States
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13
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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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McMahon SJ. The linear quadratic model: usage, interpretation and challenges. ACTA ACUST UNITED AC 2018; 64:01TR01. [DOI: 10.1088/1361-6560/aaf26a] [Citation(s) in RCA: 125] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Stewart RD, Carlson DJ, Butkus MP, Hawkins R, Friedrich T, Scholz M. A comparison of mechanism-inspired models for particle relative biological effectiveness (RBE). Med Phys 2018; 45:e925-e952. [PMID: 30421808 DOI: 10.1002/mp.13207] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 09/05/2018] [Accepted: 09/13/2018] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND AND SIGNIFICANCE The application of heavy ion beams in cancer therapy must account for the increasing relative biological effectiveness (RBE) with increasing penetration depth when determining dose prescriptions and organ at risk (OAR) constraints in treatment planning. Because RBE depends in a complex manner on factors such as the ion type, energy, cell and tissue radiosensitivity, physical dose, biological endpoint, and position within and outside treatment fields, biophysical models reflecting these dependencies are required for the personalization and optimization of treatment plans. AIM To review and compare three mechanism-inspired models which predict the complexities of particle RBE for various ion types, energies, linear energy transfer (LET) values and tissue radiation sensitivities. METHODS The review of models and mechanisms focuses on the Local Effect Model (LEM), the Microdosimetric-Kinetic (MK) model, and the Repair-Misrepair-Fixation (RMF) model in combination with the Monte Carlo Damage Simulation (MCDS). These models relate the induction of potentially lethal double strand breaks (DSBs) to the subsequent interactions and biological processing of DSB into more lethal forms of damage. A key element to explain the increased biological effectiveness of high LET ions compared to MV x rays is the characterization of the number and local complexity (clustering) of the initial DSB produced within a cell. For high LET ions, the spatial density of DSB induction along an ion's trajectory is much greater than along the path of a low LET electron, such as the secondary electrons produced by the megavoltage (MV) x rays used in conventional radiation therapy. The main aspects of the three models are introduced and the conceptual similarities and differences are critiqued and highlighted. Model predictions are compared in terms of the RBE for DSB induction and for reproductive cell survival. RESULTS AND CONCLUSIONS Comparisons of the RBE for DSB induction and for cell survival are presented for proton (1 H), helium (4 He), and carbon (12 C) ions for the therapeutically most relevant range of ion beam energies. The reviewed models embody mechanisms of action acting over the spatial scales underlying the biological processing of potentially lethal DSB into more lethal forms of damage. Differences among the number and types of input parameters, relevant biological targets, and the computational approaches among the LEM, MK and RMF models are summarized and critiqued. Potential experiments to test some of the seemingly contradictory aspects of the models are discussed.
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Affiliation(s)
- Robert D Stewart
- Department of Radiation Oncology, University of Washington School of Medicine, 1959 NE Pacific Street, Box 356043, Seattle, WA, 98195, USA
| | - David J Carlson
- Department of Therapeutic Radiology, Yale University, New Haven, CT, USA
| | - Michael P Butkus
- Department of Therapeutic Radiology, Yale University, New Haven, CT, USA
| | - Roland Hawkins
- Radiation Oncology Center, Ochsner Clinic Foundation, New Orleans, LA, 70121, USA
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Einbeck J, Ainsbury EA, Sales R, Barnard S, Kaestle F, Higueras M. A statistical framework for radiation dose estimation with uncertainty quantification from the γ-H2AX assay. PLoS One 2018; 13:e0207464. [PMID: 30485322 PMCID: PMC6261578 DOI: 10.1371/journal.pone.0207464] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 10/31/2018] [Indexed: 11/18/2022] Open
Abstract
Over the last decade, the γ–H2AX focus assay, which exploits the phosphorylation of the H2AX histone following DNA double–strand–breaks, has made considerable progress towards acceptance as a reliable biomarker for exposure to ionizing radiation. While the existing literature has convincingly demonstrated a dose–response effect, and also presented approaches to dose estimation based on appropriately defined calibration curves, a more widespread practical use is still hampered by a certain lack of discussion and agreement on the specific dose–response modelling and uncertainty quantification strategies, as well as by the unavailability of implementations. This manuscript intends to fill these gaps, by stating explicitly the statistical models and techniques required for calibration curve estimation and subsequent dose estimation. Accompanying this article, a web applet has been produced which implements the discussed methods.
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Affiliation(s)
- Jochen Einbeck
- Department of Mathematical Sciences, Durham University, Durham, United Kingdom
- * E-mail:
| | - Elizabeth A. Ainsbury
- Public Health England, Chemical and Environmental Hazards, Chilton, Didcot, United Kingdom
| | - Rachel Sales
- Department of Mathematical Sciences, Durham University, Durham, United Kingdom
| | - Stephen Barnard
- Public Health England, Chemical and Environmental Hazards, Chilton, Didcot, United Kingdom
| | - Felix Kaestle
- Bundesamt für Strahlenschutz, Fachbereich Strahlenschutz und Gesundheit, Oberschleissheim, Germany
| | - Manuel Higueras
- Departamento de Matemáticas y Computación, Universidad de La Rioja, Logroño, La Rioja, Spain
- Basque Center for Applied Mathematics, Bilbao, Basque Country, Spain
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Stewart RD. Induction of DNA Damage by Light Ions Relative to 60Co γ-rays. Int J Part Ther 2018; 5:25-39. [PMID: 31773018 PMCID: PMC6871587 DOI: 10.14338/ijpt-18-00030] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 06/21/2018] [Indexed: 12/20/2022] Open
Abstract
The specific types and numbers of clusters of DNA lesions, including both DNA double-strand breaks (DSBs) and non-DSB clusters, are widely considered 1 of the most important initiating events underlying the relative biological effectiveness (RBE) of the light ions of interest in the treatment of cancer related to megavoltage x-rays and 60Co γ-rays. This review summarizes the categorization of DNA damage, reviews the underlying mechanisms of action by ionizing radiation, and quantifies the general trends in DSB and non-DSB cluster formation by light ions under normoxic and anoxic conditions, as predicted by Monte Carlo simulations that reflect the accumulated evidence from decades of research on radiation damage to DNA. The significance of the absolute and relative numbers of clusters and the local complexity of DSB and non-DSB clusters are discussed in relation to the formation of chromosome aberrations and the loss of cell reproductive capacity. Clinical implications of the dependence of DSB induction on ionization density is reviewed with an eye towards increasing the therapeutic ratio of proton and carbon ion therapy through the explicit optimization of RBE-weighted dose.
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Affiliation(s)
- Robert D. Stewart
- Department of Radiation Oncology, University of Washington School of Medicine, Seattle, WA, USA
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18
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Rosin LF, Nguyen SC, Joyce EF. Condensin II drives large-scale folding and spatial partitioning of interphase chromosomes in Drosophila nuclei. PLoS Genet 2018; 14:e1007393. [PMID: 30001329 PMCID: PMC6042687 DOI: 10.1371/journal.pgen.1007393] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 05/03/2018] [Indexed: 12/26/2022] Open
Abstract
Metazoan chromosomes are folded into discrete sub-nuclear domains, referred to as chromosome territories (CTs). The molecular mechanisms that underlie the formation and maintenance of CTs during the cell cycle remain largely unknown. Here, we have developed high-resolution chromosome paints to investigate CT organization in Drosophila cycling cells. We show that large-scale chromosome folding patterns and levels of chromosome intermixing are remarkably stable across various cell types. Our data also suggest that the nucleus scales to accommodate fluctuations in chromosome size throughout the cell cycle, which limits the degree of intermixing between neighboring CTs. Finally, we show that the cohesin and condensin complexes are required for different scales of chromosome folding, with condensin II being especially important for the size, shape, and level of intermixing between CTs in interphase. These findings suggest that large-scale chromosome folding driven by condensin II influences the extent to which chromosomes interact, which may have direct consequences for cell-type specific genome stability.
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Affiliation(s)
- Leah F. Rosin
- Department of Genetics, Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Son C. Nguyen
- Department of Genetics, Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Eric F. Joyce
- Department of Genetics, Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
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Testa A, Ballarini F, Giesen U, Gil OM, Carante MP, Tello J, Langner F, Rabus H, Palma V, Pinto M, Patrono C. Analysis of Radiation-Induced Chromosomal Aberrations on a Cell-by-Cell Basis after Alpha-Particle Microbeam Irradiation: Experimental Data and Simulations. Radiat Res 2018; 189:597-604. [PMID: 29624483 DOI: 10.1667/rr15005.1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
There is a continued need for further clarification of various aspects of radiation-induced chromosomal aberration, including its correlation with radiation track structure. As part of the EMRP joint research project, Biologically Weighted Quantities in Radiotherapy (BioQuaRT), we performed experimental and theoretical analyses on chromosomal aberrations in Chinese hamster ovary cells (CHO-K1) exposed to α particles with final energies of 5.5 and 17.8 MeV (absorbed doses: ∼2.3 Gy and ∼1.9 Gy, respectively), which were generated by the microbeam at the Physikalisch-Technische Bundesanstalt (PTB) in Braunschweig, Germany. In line with the differences in linear energy transfer (approximately 85 keV/μm for 5.5 MeV and 36 keV/μm for 17.8 MeV α particles), the 5.5 MeV α particles were more effective than the 17.8 MeV α particles, both in terms of the percentage of aberrant cells (57% vs. 33%) and aberration frequency. The yield of total aberrations increased by a factor of ∼2, although the increase in dicentrics plus centric rings was less pronounced than in acentric fragments. The experimental data were compared with Monte Carlo simulations based on the BIophysical ANalysis of Cell death and chromosomal Aberrations model (BIANCA). This comparison allowed interpretation of the results in terms of critical DNA damage [cluster lesions (CLs)]. More specifically, the higher aberration yields observed for the 5.5 MeV α particles were explained by taking into account that, although the nucleus was traversed by fewer particles (nominally, 11 vs. 25), each particle was much more effective (by a factor of ∼3) at inducing CLs. This led to an increased yield of CLs per cell (by a factor of ∼1.4), consistent with the increased yield of total aberrations observed in the experiments.
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Affiliation(s)
- Antonella Testa
- a Territorial and Production Systems Sustainability Department, Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), Rome, Italy
| | - Francesca Ballarini
- b University of Pavia (Physics Department), via Bassi 6, I-27100 Pavia, Italy.,c INFN (Italian National Institute of Nuclear Physics), Section of Pavia, I-27100 Pavia, Italy
| | - Ulrich Giesen
- d Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116 Braunschweig, Germany
| | - Octávia Monteiro Gil
- e Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Bobadela-LRS, Lisbon, Portugal
| | - Mario P Carante
- b University of Pavia (Physics Department), via Bassi 6, I-27100 Pavia, Italy.,c INFN (Italian National Institute of Nuclear Physics), Section of Pavia, I-27100 Pavia, Italy
| | - John Tello
- b University of Pavia (Physics Department), via Bassi 6, I-27100 Pavia, Italy.,c INFN (Italian National Institute of Nuclear Physics), Section of Pavia, I-27100 Pavia, Italy.,f Universidade Estadual de Campinas, Campinas, SP, Brazil
| | - Frank Langner
- d Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116 Braunschweig, Germany
| | - Hans Rabus
- d Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116 Braunschweig, Germany
| | - Valentina Palma
- a Territorial and Production Systems Sustainability Department, Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), Rome, Italy
| | - Massimo Pinto
- g National Institute of Ionizing Radiation Metrology, Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), Rome, Italy
| | - Clarice Patrono
- a Territorial and Production Systems Sustainability Department, Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), Rome, Italy
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Nikitaki Z, Holá M, Donà M, Pavlopoulou A, Michalopoulos I, Angelis KJ, Georgakilas AG, Macovei A, Balestrazzi A. Integrating plant and animal biology for the search of novel DNA damage biomarkers. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2018; 775:21-38. [DOI: 10.1016/j.mrrev.2018.01.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 01/08/2018] [Accepted: 01/16/2018] [Indexed: 12/11/2022]
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21
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Meyer J, Stewart RD, Smith D, Eagle J, Lee E, Cao N, Ford E, Hashemian R, Schuemann J, Saini J, Marsh S, Emery R, Dorman E, Schwartz J, Sandison G. Biological and dosimetric characterisation of spatially fractionated proton minibeams. Phys Med Biol 2017; 62:9260-9281. [PMID: 29053105 DOI: 10.1088/1361-6560/aa950c] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The biological effectiveness of proton beams varies with depth, spot size and lateral distance from the beam central axis. The aim of this work is to incorporate proton relative biological effectiveness (RBE) and equivalent uniform dose (EUD) considerations into comparisons of broad beam and highly modulated proton minibeams. A Monte Carlo model of a small animal proton beamline is presented. Dose and variable RBE is calculated on a per-voxel basis for a range of energies (30-109 MeV). For an open beam, the RBE values at the beam entrance ranged from 1.02-1.04, at the Bragg peak (BP) from 1.3 to 1.6, and at the distal end of the BP from 1.4 to 2.0. For a 50 MeV proton beam, a minibeam collimator designed to produce uniform dose at the depth of the BP peak, had minimal impact on the open beam RBE values at depth. RBE changes were observed near the surface when the collimator was placed flush with the irradiated object, due to a higher neutron contribution derived from proton interactions with the collimator. For proton minibeams, the relative mean RBE weighted entrance dose (RWD) was ~25% lower than the physical mean dose. A strong dependency of the EUD with fraction size was observed. For 20 Gy fractions, the EUD varied widely depending on the radiosensitivity of the cells. For radiosensitive cells, the difference was up to ~50% in mean dose and ~40% in mean RWD and the EUD trended towards the valley dose rather than the mean dose. For comparative studies of uniform dose with spatially fractionated proton minibeams, EUD derived from a per-voxel RWD distribution is recommended for biological assessments of reproductive cell survival and related endpoints.
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Affiliation(s)
- Juergen Meyer
- Department of Radiation Oncology, University of Washington, 1959 NE Pacific Street, Box 356043, Seattle, WA 98195, United States of America
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22
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Streitmatter SW, Stewart RD, Jenkins PA, Jevremovic T. DNA double strand break (DSB) induction and cell survival in iodine-enhanced computed tomography (CT). Phys Med Biol 2017; 62:6164-6184. [PMID: 28703119 DOI: 10.1088/1361-6560/aa772d] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
A multi-scale Monte Carlo model is proposed to assess the dosimetric and biological impact of iodine-based contrast agents commonly used in computed tomography. As presented, the model integrates the general purpose MCNP6 code system for larger-scale radiation transport and dose assessment with the Monte Carlo damage simulation to determine the sub-cellular characteristics and spatial distribution of initial DNA damage. The repair-misrepair-fixation model is then used to relate DNA double strand break (DSB) induction to reproductive cell death. Comparisons of measured and modeled changes in reproductive cell survival for ultrasoft characteristic k-shell x-rays (0.25-4.55 keV) up to orthovoltage (200-500 kVp) x-rays indicate that the relative biological effectiveness (RBE) for DSB induction is within a few percent of the RBE for cell survival. Because of the very short range of secondary electrons produced by low energy x-ray interactions with contrast agents, the concentration and subcellular distribution of iodine within and near cellular targets have a significant impact on the estimated absorbed dose and number of DSB produced in the cell nucleus. For some plausible models of the cell-level distribution of contrast agent, the model predicts an increase in RBE-weighted dose (RWD) for the endpoint of DSB induction of 1.22-1.40 for a 5-10 mg ml-1 iodine concentration in blood compared to an RWD increase of 1.07 ± 0.19 from a recent clinical trial. The modeled RWD of 2.58 ± 0.03 is also in good agreement with the measured RWD of 2.3 ± 0.5 for an iodine concentration of 50 mg ml-1 relative to no iodine. The good agreement between modeled and measured DSB and cell survival estimates provides some confidence that the presented model can be used to accurately assess biological dose for other concentrations of the same or different contrast agents.
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Affiliation(s)
- Seth W Streitmatter
- Nuclear Engineering Program, The University of Utah, 50 S. Central Campus Drive, 1206 MEB, Salt Lake City, UT 84112, United States of America. Department of Radiology and Imaging Sciences, University of Utah Health, 30 North 1900 East #1A71, Salt Lake City, UT 84132, United States of America
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Shuryak I, Loucas BD, Cornforth MN. Seeking Beta: Experimental Considerations and Theoretical Implications Regarding the Detection of Curvature in Dose-Response Relationships for Chromosome Aberrations. Radiat Res 2017; 187:7-19. [PMID: 28085640 DOI: 10.1667/rr14520.1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The concept of curvature in dose-response relationships figures prominently in radiation biology, encompassing a wide range of interests including radiation protection, radiotherapy and fundamental models of radiation action. In this context, the ability to detect even small amounts of curvature becomes important. Standard (ST) statistical approaches used for this purpose typically involve least-squares regression, followed by a test on sums of squares. Because we have found that these methods are not particularly robust, we investigated an alternative information theoretic (IT) approach, which involves Poisson regression followed by information-theoretic model selection. Our first objective was to compare the performances of the ST and IT methods by using them to analyze mFISH data on gamma-ray-induced simple interchanges in human lymphocytes, and on Monte Carlo simulated data. Real and simulated data sets that contained small-to-moderate curvature were deliberately selected for this exercise. The IT method tended to detect curvature with higher confidence than the ST method. The finding of curvature in the dose response for true simple interchanges is discussed in the context of fundamental models of radiation action. Our second objective was to optimize the design of experiments aimed specifically at detecting curvature. We used Monte Carlo simulation to investigate the following parameters. Constrained by available resources (i.e., the total number of cells to be scored) these include: the optimal number of dose points to use; the best way to apportion the total number of cells among these dose points; and the spacing of dose intervals. Counterintuitively, our simulation results suggest that 4-5 radiation doses were typically optimal, whereas adding more dose points may actually prove detrimental. Superior results were also obtained by implementing unequal dose spacing and unequal distributions in the number of cells scored at each dose.
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Affiliation(s)
- Igor Shuryak
- a Center for Radiological Research, Columbia University, New York, New York
| | - Bradford D Loucas
- b Department of Radiation Oncology, University of Texas Medical Branch, Galveston, Texas
| | - Michael N Cornforth
- b Department of Radiation Oncology, University of Texas Medical Branch, Galveston, Texas
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Mechanistic Modelling of DNA Repair and Cellular Survival Following Radiation-Induced DNA Damage. Sci Rep 2016; 6:33290. [PMID: 27624453 PMCID: PMC5022028 DOI: 10.1038/srep33290] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 08/09/2016] [Indexed: 12/12/2022] Open
Abstract
Characterising and predicting the effects of ionising radiation on cells remains challenging, with the lack of robust models of the underlying mechanism of radiation responses providing a significant limitation to the development of personalised radiotherapy. In this paper we present a mechanistic model of cellular response to radiation that incorporates the kinetics of different DNA repair processes, the spatial distribution of double strand breaks and the resulting probability and severity of misrepair. This model enables predictions to be made of a range of key biological endpoints (DNA repair kinetics, chromosome aberration and mutation formation, survival) across a range of cell types based on a set of 11 mechanistic fitting parameters that are common across all cells. Applying this model to cellular survival showed its capacity to stratify the radiosensitivity of cells based on aspects of their phenotype and experimental conditions such as cell cycle phase and plating delay (correlation between modelled and observed Mean Inactivation Doses R(2) > 0.9). By explicitly incorporating underlying mechanistic factors, this model can integrate knowledge from a wide range of biological studies to provide robust predictions and may act as a foundation for future calculations of individualised radiosensitivity.
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Schipler A, Mladenova V, Soni A, Nikolov V, Saha J, Mladenov E, Iliakis G. Chromosome thripsis by DNA double strand break clusters causes enhanced cell lethality, chromosomal translocations and 53BP1-recruitment. Nucleic Acids Res 2016; 44:7673-90. [PMID: 27257076 PMCID: PMC5027484 DOI: 10.1093/nar/gkw487] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Accepted: 05/19/2016] [Indexed: 01/04/2023] Open
Abstract
Chromosome translocations are hallmark of cancer and of radiation-induced cell killing, reflecting joining of incongruent DNA-ends that alter the genome. Translocation-formation requires DNA end-joining mechanisms and incompletely characterized, permissive chromatin conditions. We show that chromatin destabilization by clusters of DNA double-strand-breaks (DSBs) generated by the I-SceI meganuclease at multiple, appropriately engineered genomic sites, compromises c-NHEJ and markedly increases cell killing and translocation-formation compared to single-DSBs. Translocation-formation from DSB-clusters utilizes Parp1 activity, implicating alt-EJ in their formation. Immunofluorescence experiments show that single-DSBs and DSB-clusters uniformly provoke the formation of single γ-H2AX foci, suggesting similar activation of early DNA damage response (DDR). Live-cell imaging also shows similar single-focus recruitment of the early-response protein MDC1, to single-DSBs and DSB-clusters. Notably, the late DDR protein, 53BP1 shows in live-cell imaging strikingly stronger recruitment to DSB-clusters as compared to single-DSBs. This is the first report that chromatin thripsis, in the form of engineered DSB-clusters, compromises first-line DSB-repair pathways, allowing alt-EJ to function as rescuing-backup. DSB-cluster-formation is indirectly linked to the increased biological effectiveness of high ionization-density radiations, such as the alpha-particles emitted by radon gas or the heavy-ions utilized in cancer therapy. Our observations provide the first direct mechanistic explanation for this long-known effect.
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Affiliation(s)
- Agnes Schipler
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, 45122 Essen, Germany
| | - Veronika Mladenova
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, 45122 Essen, Germany
| | - Aashish Soni
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, 45122 Essen, Germany
| | - Vladimir Nikolov
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, 45122 Essen, Germany
| | - Janapriya Saha
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, 45122 Essen, Germany
| | - Emil Mladenov
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, 45122 Essen, Germany
| | - George Iliakis
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, 45122 Essen, Germany
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Warth A, Endris V, Stenzinger A, Penzel R, Harms A, Duell T, Abdollahi A, Lindner M, Schirmacher P, Muley T, Dienemann H, Fink L, Morresi-Hauf A, Pfarr N, Weichert W. Genetic changes of non-small cell lung cancer under neoadjuvant therapy. Oncotarget 2016; 7:29761-9. [PMID: 27105513 PMCID: PMC5045431 DOI: 10.18632/oncotarget.8858] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Accepted: 03/28/2016] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Large scale sequencing efforts defined common molecular alterations in non-small cell lung cancer (NSCLC) and revealed potentially druggable mutations. Yet, systematic data on the changes of the respective molecular profiles under standard therapy in NSCLC are limited. RESULTS 14 out of 68 observed coding mutations (21%) and 6 out of 33 (18%) copy number variations (CNV) were lost or gained during therapy. Mutational and CNV changes clustered in 6/37 (16%) and 3/37 (8%) patients. Changes in clinically relevant mutations were rare but present in single cases for genes such as BRAF and PIK3CA. The type of radiochemotherapy but not the duration of therapy impacted on the frequency of mutational changes. METHODS We established a lung cancer specific next-generation sequencing panel covering ~7500 hotspots of 41 genes frequently mutated in NSCLC and performed ultradeep multigene sequencing of 37 corresponding pre- and post-therapeutic formalin fixed paraffin-embedded specimens to discover mutational changes and copy number variations under neo-adjuvant radio- (RTX) and/or chemotherapy (CTX). CONCLUSION We unraveled changes in common driver gene candidates in NSCLC under neo-adjuvant therapy. Our data shed first light on the genetic changes of NSCLC under conventional therapy and might be taken into account when the relevance of sequential biopsy approaches is discussed.
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Affiliation(s)
- Arne Warth
- Institute of Pathology, Heidelberg University, Heidelberg, Germany
| | - Volker Endris
- Institute of Pathology, Heidelberg University, Heidelberg, Germany
| | | | - Roland Penzel
- Institute of Pathology, Heidelberg University, Heidelberg, Germany
| | - Alexander Harms
- Institute of Pathology, Heidelberg University, Heidelberg, Germany
| | - Thomas Duell
- Department of Pneumology and Thoracic Oncology, Asklepios Hospital, Munich-Gauting, Germany
| | - Amir Abdollahi
- Department of Radiation Oncology, Heidelberg University, Heidelberg, Germany
| | - Michael Lindner
- Department of Thoracic Surgery, Asklepios Hospital, Munich-Gauting, Germany
| | | | - Thomas Muley
- Translational Research Unit, Thoraxklinik at Heidelberg University, Heidelberg, Germany
| | - Hendrik Dienemann
- Department of Thoracic Surgery, Thoraxklinik at Heidelberg University, Heidelberg, Germany
| | | | | | - Nicole Pfarr
- Institute of Pathology, Heidelberg University, Heidelberg, Germany
- Institute of Pathology, Technical University (TUM), Munich, Germany
| | - Wilko Weichert
- Institute of Pathology, Heidelberg University, Heidelberg, Germany
- National Center for Tumor Diseases (NCT), Heidelberg, Germany
- Institute of Pathology, Technical University (TUM), Munich, Germany
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Rall M, Kraft D, Volcic M, Cucu A, Nasonova E, Taucher-Scholz G, Bönig H, Wiesmüller L, Fournier C. Impact of Charged Particle Exposure on Homologous DNA Double-Strand Break Repair in Human Blood-Derived Cells. Front Oncol 2015; 5:250. [PMID: 26618143 PMCID: PMC4641431 DOI: 10.3389/fonc.2015.00250] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Accepted: 10/26/2015] [Indexed: 12/12/2022] Open
Abstract
Ionizing radiation generates DNA double-strand breaks (DSB) which, unless faithfully repaired, can generate chromosomal rearrangements in hematopoietic stem and/or progenitor cells (HSPC), potentially priming the cells towards a leukemic phenotype. Using an enhanced green fluorescent protein (EGFP)-based reporter system, we recently identified differences in the removal of enzyme-mediated DSB in human HSPC versus mature peripheral blood lymphocytes (PBL), particularly regarding homologous DSB repair (HR). Assessment of chromosomal breaks via premature chromosome condensation or γH2AX foci indicated similar efficiency and kinetics of radiation-induced DSB formation and rejoining in PBL and HSPC. Prolonged persistence of chromosomal breaks was observed for higher LET charged particles which are known to induce more complex DNA damage compared to X-rays. Consistent with HR deficiency in HSPC observed in our previous study, we noticed here pronounced focal accumulation of 53BP1 after X-ray and carbon ion exposure (intermediate LET) in HSPC versus PBL. For higher LET, 53BP1 foci kinetics was similarly delayed in PBL and HSPC suggesting similar failure to repair complex DNA damage. Data obtained with plasmid reporter systems revealed a dose- and LET-dependent HR increase after X-ray, carbon ion and higher LET exposure, particularly in HR-proficient immortalized and primary lymphocytes, confirming preferential use of conservative HR in PBL for intermediate LET damage repair. HR measured adjacent to the leukemia-associated MLL breakpoint cluster sequence in reporter lines revealed dose dependency of potentially leukemogenic rearrangements underscoring the risk of leukemia-induction by radiation treatment.
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Affiliation(s)
- Melanie Rall
- Department of Obstetrics and Gynaecology, Ulm University, Ulm, Germany
| | - Daniela Kraft
- Department of Biophysics, GSI Helmholtz Center for Heavy Ion Research, Darmstadt, Germany
| | - Meta Volcic
- Department of Obstetrics and Gynaecology, Ulm University, Ulm, Germany
| | - Aljona Cucu
- Department of Biophysics, GSI Helmholtz Center for Heavy Ion Research, Darmstadt, Germany
| | - Elena Nasonova
- Department of Biophysics, GSI Helmholtz Center for Heavy Ion Research, Darmstadt, Germany
| | - Gisela Taucher-Scholz
- Department of Biophysics, GSI Helmholtz Center for Heavy Ion Research, Darmstadt, Germany
| | - Halvard Bönig
- German Red Cross Blood Service Baden-Wuerttemberg – Hessen, Institute for Transfusion Medicine and Immunohematology, Johann Wolfgang Goethe-University Hospital, Frankfurt, Germany
| | - Lisa Wiesmüller
- Department of Obstetrics and Gynaecology, Ulm University, Ulm, Germany
- *Correspondence: Lisa Wiesmüller, ; Claudia Fournier,
| | - Claudia Fournier
- Department of Biophysics, GSI Helmholtz Center for Heavy Ion Research, Darmstadt, Germany
- *Correspondence: Lisa Wiesmüller, ; Claudia Fournier,
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Oliveira M, Einbeck J, Higueras M, Ainsbury E, Puig P, Rothkamm K. Zero-inflated regression models for radiation-induced chromosome aberration data: A comparative study. Biom J 2015; 58:259-79. [PMID: 26461836 DOI: 10.1002/bimj.201400233] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Revised: 07/29/2015] [Accepted: 08/03/2015] [Indexed: 11/11/2022]
Abstract
Within the field of cytogenetic biodosimetry, Poisson regression is the classical approach for modeling the number of chromosome aberrations as a function of radiation dose. However, it is common to find data that exhibit overdispersion. In practice, the assumption of equidispersion may be violated due to unobserved heterogeneity in the cell population, which will render the variance of observed aberration counts larger than their mean, and/or the frequency of zero counts greater than expected for the Poisson distribution. This phenomenon is observable for both full- and partial-body exposure, but more pronounced for the latter. In this work, different methodologies for analyzing cytogenetic chromosomal aberrations datasets are compared, with special focus on zero-inflated Poisson and zero-inflated negative binomial models. A score test for testing for zero inflation in Poisson regression models under the identity link is also developed.
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Affiliation(s)
- María Oliveira
- Department of Mathematical Sciences, Durham University, Durham DH1 3LE, UK
| | - Jochen Einbeck
- Department of Mathematical Sciences, Durham University, Durham DH1 3LE, UK
| | - Manuel Higueras
- Centre for Radiation, Chemical and Environmental Hazards (CRCE), Public Health England, Chilton, Didcot, Oxon OX11 0RQ, UK.,Departament de Matematiques, Universitat Autonoma de Barcelona, Bellaterra (Barcelona) 08193, Spain
| | - Elizabeth Ainsbury
- Centre for Radiation, Chemical and Environmental Hazards (CRCE), Public Health England, Chilton, Didcot, Oxon OX11 0RQ, UK
| | - Pedro Puig
- Departament de Matematiques, Universitat Autonoma de Barcelona, Bellaterra (Barcelona) 08193, Spain
| | - Kai Rothkamm
- Centre for Radiation, Chemical and Environmental Hazards (CRCE), Public Health England, Chilton, Didcot, Oxon OX11 0RQ, UK.,Department of Radiotherapy & Radio-Oncology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
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29
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Stewart RD, Streitmatter SW, Argento DC, Kirkby C, Goorley JT, Moffitt G, Jevremovic T, Sandison GA. Rapid MCNP simulation of DNA double strand break (DSB) relative biological effectiveness (RBE) for photons, neutrons, and light ions. Phys Med Biol 2015; 60:8249-74. [PMID: 26449929 DOI: 10.1088/0031-9155/60/21/8249] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
To account for particle interactions in the extracellular (physical) environment, information from the cell-level Monte Carlo damage simulation (MCDS) for DNA double strand break (DSB) induction has been integrated into the general purpose Monte Carlo N-particle (MCNP) radiation transport code system. The effort to integrate these models is motivated by the need for a computationally efficient model to accurately predict particle relative biological effectiveness (RBE) in cell cultures and in vivo. To illustrate the approach and highlight the impact of the larger scale physical environment (e.g. establishing charged particle equilibrium), we examined the RBE for DSB induction (RBEDSB) of x-rays, (137)Cs γ-rays, neutrons and light ions relative to γ-rays from (60)Co in monolayer cell cultures at various depths in water. Under normoxic conditions, we found that (137)Cs γ-rays are about 1.7% more effective at creating DSB than γ-rays from (60)Co (RBEDSB = 1.017) whereas 60-250 kV x-rays are 1.1 to 1.25 times more efficient at creating DSB than (60)Co. Under anoxic conditions, kV x-rays may have an RBEDSB up to 1.51 times as large as (60)Co γ-rays. Fission neutrons passing through monolayer cell cultures have an RBEDSB that ranges from 2.6 to 3.0 in normoxic cells, but may be as large as 9.93 for anoxic cells. For proton pencil beams, Monte Carlo simulations suggest an RBEDSB of about 1.2 at the tip of the Bragg peak and up to 1.6 a few mm beyond the Bragg peak. Bragg peak RBEDSB increases with decreasing oxygen concentration, which may create opportunities to apply proton dose painting to help address tumor hypoxia. Modeling of the particle RBE for DSB induction across multiple physical and biological scales has the potential to aid in the interpretation of laboratory experiments and provide useful information to advance the safety and effectiveness of hadron therapy in the treatment of cancer.
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Affiliation(s)
- Robert D Stewart
- Department of Radiation Oncology, University of Washington School of Medicine, School of Medicine, 1959 NE Pacific Street, Box 356043, Seattle, WA 98195, USA
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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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31
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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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Heidari MH, Porghasem M, Mirzaei N, Mohseni JH, Heidari M, Azargashb E, Movafagh A, Heidari R, Molouki A, Larijani L. The effect of high level natural ionizing radiation on expression of PSA, CA19-9 and CEA tumor markers in blood serum of inhabitants of Ramsar, Iran. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2014; 128:64-67. [PMID: 24292395 DOI: 10.1016/j.jenvrad.2013.11.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Revised: 09/03/2013] [Accepted: 11/01/2013] [Indexed: 06/02/2023]
Abstract
Since several high level natural radiation areas (HLNRAs) exist on our planet, considerable attention has been drawn to health issues that may develop as the result of visiting or living in such places. City of Ramsar in Iran is an HNLRA, and is a tourist attraction mainly due to its hot spas. However, the growing awareness over its natural radiation sources has prompted widespread scientific investigation at national level. In this study, using an ELISA method, the level of expression of three tumor markers known as carcinoembryonic antigen (CEA), prostate-specific antigen (PSA) and carcino antigen 19-9 (CA19-9) in blood serum of 40 local men of Ramsar (subject group) was investigated and compared to 40 men from the city of Noshahr (control group). Noshahr was previously identified as a normal level natural radiation area (NLNRA) that is some 85 km far from Ramsar. According to statistical analysis, there was a significant difference in the levels of PSA and CA19-9 markers between the two groups (p < 0.001) with those of Ramsar being considerably higher. CEA level did not show any difference. Although some of the volunteers tested positive to the markers, they were in good health as confirmed by the physician. Moreover, the high number of positive markers in Noshahr was considerable. Therefore, future study is needed to further validate this result and to determine the level of positivity to tumor markers in both cities.
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Affiliation(s)
- Mohammad Hassan Heidari
- Department of Anatomy and Biology, Proteomics Laboatory, Shahid Beheshti University of Medical Sciences, Velenjak, Tehran, Iran.
| | - Mohsen Porghasem
- Department of Anatomical Science, Babol University of Medical Sciences, Babol, Iran
| | | | | | - Matine Heidari
- Medical School, Tehran University of Medical Sciences, Tehran, Iran
| | - Eznollah Azargashb
- Department of Health and Social Medical Researches, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Abolfazl Movafagh
- Department of Clinical Genetics, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Reihane Heidari
- Amiralam Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | - Aidin Molouki
- Institute of Bioscience, University Putra Malaysia, Serdang, Selangor DE, Malaysia
| | - Leila Larijani
- Department of Anatomy and Biology, Proteomics Laboatory, Shahid Beheshti University of Medical Sciences, Velenjak, Tehran, Iran
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Friedland W, Kundrát P. Track structure based modelling of chromosome aberrations after photon and alpha-particle irradiation. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2013; 756:213-23. [DOI: 10.1016/j.mrgentox.2013.06.013] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Accepted: 06/18/2013] [Indexed: 02/01/2023]
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34
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Georgakilas AG, O'Neill P, Stewart RD. Induction and Repair of Clustered DNA Lesions: What Do We Know So Far? Radiat Res 2013; 180:100-109. [DOI: 10.1667/rr3041.1] [Citation(s) in RCA: 216] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023]
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35
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Vinnikov VA, Maznyk NA. Cytogenetic dose-response in vitro for biological dosimetry after exposure to high doses of gamma-rays. RADIATION PROTECTION DOSIMETRY 2013; 154:186-197. [PMID: 22923248 DOI: 10.1093/rpd/ncs200] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The dose response for dicentrics plus centric rings and total unstable chromosome-type aberrations was studied in the first mitoses of cultured human peripheral blood lymphocytes irradiated in vitro to doses of ∼2, 4, 6, 8, 10, 16 and 20 Gy of acute (60)Со gamma-rays. A dose-dependent increase of aberration yield was accompanied by a tendency to the underdispersion of dicentrics and centric rings among cells distributions compared with Poisson statistics at doses ≥6 Gy. The formal fitting of the data to a linear-quadratic model resulted in an equation with the linear and quadratic coefficients ranged 0.098-0.129×cell(-1)×Gy(-1) and 0.039-0.034×cell(-1)×Gy(-2), respectively, depending on the fitting method. The actual radiation-induced aberration yield was markedly lower than expected from a calibration curve, generated earlier within a lower dose range. Interlaboratory variations in reported dicentric yields induced by medium-to-high radiation doses in vitro are discussed.
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Affiliation(s)
- Volodymyr A Vinnikov
- Radiation Cytogenetics Laboratory, Grigoriev Institute for Medical Radiology of the National Academy of Medical Science of Ukraine, Pushkinskaya St. 82, Kharkiv 61024, Ukraine.
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Barnard S, Bouffler S, Rothkamm K. The shape of the radiation dose response for DNA double-strand break induction and repair. Genome Integr 2013; 4:1. [PMID: 23522792 PMCID: PMC3616853 DOI: 10.1186/2041-9414-4-1] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Accepted: 03/18/2013] [Indexed: 12/22/2022] Open
Abstract
DNA double-strand breaks are among the most deleterious lesions induced by ionising radiation. A range of inter-connected cellular response mechanisms has evolved to enable their efficient repair and thus protect the cell from the harmful consequences of un- or mis-repaired breaks which may include early effects such as cell killing and associated acute toxicities and late effects such as cancer. A number of studies suggest that the induction and repair of double-strand breaks may not always occur linearly with ionising radiation dose. Here we have aimed to identify and discuss some of the biological and methodological factors that can potentially modify the shape of the dose response curve obtained for these endpoints using the most common assays for double-strand breaks, pulsed-field gel electrophoresis and microscopic scoring of radiation-induced foci.
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Affiliation(s)
- Stephen Barnard
- Health Protection Agency Centre for Radiation, Chemical and Environmental Hazards, Chilton, Didcot, Oxon OX11 0RQ, UK.
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37
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Evdokimova V, Gandhi M, Rayapureddi J, Stringer JR, Nikiforov YE. Formation of carcinogenic chromosomal rearrangements in human thyroid cells after induction of double-strand DNA breaks by restriction endonucleases. Endocr Relat Cancer 2012; 19:271-81. [PMID: 22323563 PMCID: PMC5828496 DOI: 10.1530/erc-11-0314] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Ionizing radiation (IR) exposure increases the risk of thyroid cancer and other cancer types. Chromosomal rearrangements, such as RET/PTC, are characteristic features of radiation-associated thyroid cancer and can be induced by radiation in vitro. IR causes double-strand breaks (DSBs), suggesting that such damage leads to RET/PTC, but the rearrangement mechanism has not been established. To study the mechanism, we explored the possibility of inducing RET/PTC by electroporation of restriction endonucleases (REs) into HTori-3 human thyroid cells. We used five REs, which induced DSB in a dose-dependent manner similar to that seen with IR. Although all but one RE caused DSB in one or more of the three genes involved in RET/PTC, rearrangement was detected only in cells electroporated with either PvuII (25 and 100 U) or StuI (100 and 250 U). The predominant rearrangement type was RET/PTC3, which is characteristic of human thyroid cancer arising early after Chernobyl-related radioactive iodine exposure. Both enzymes that produced RET/PTC had restriction sites only in one of the two fusion partner genes. Moreover, the two enzymes that produced RET/PTC had restriction sites present in clusters, which was not the case for RE that failed to induce RET/PTC. In summary, we establish a model of DSB induction by RE and report for the first time the formation of carcinogenic chromosomal rearrangements, predominantly RET/PTC3, as a result of DSB produced by RE. Our data also raise a possibility that RET/PTC rearrangement can be initiated by a complex DSB that is induced in one of the fusion partner genes.
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Affiliation(s)
- Viktoria Evdokimova
- Department of Pathology, University of Pittsburgh, 200 Lothrop Street, PUH, Room C-606, Pittsburgh, Pennsylvania 15213, USA
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Paz-y-Miño C, Cumbal N, Sánchez ME. Genotoxicity studies performed in the ecuadorian population. Mol Biol Int 2012; 2012:598984. [PMID: 22496977 PMCID: PMC3306904 DOI: 10.1155/2012/598984] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2011] [Revised: 11/25/2011] [Accepted: 12/05/2011] [Indexed: 01/01/2023] Open
Abstract
Genotoxicity studies in Ecuador have been carried out during the past two decades. The focuses of the research were mainly the area of environmental issues, where the populations have been accidentally exposed to contaminants and the area of occupational exposure of individuals at the workplace. This paper includes studies carried out in the population of the Amazon region, a zone known for its rich biodiversity as well as for the ecological damage caused by oil spills and chemical sprayings whose consequences continue to be controversial. Additionally, we show the results of studies comprised of individuals occupationally exposed to toxic agents in two very different settings: flower plantation workers exposed to pesticide mixtures and X-ray exposure of hospital workers. The results from these studies confirm that genotoxicity studies can help evaluate current conditions and prevent further damage in the populations exposed to contaminants. As such, they are evidence of the need for biomonitoring employers at risk, stricter law enforcement regarding the use of pesticides, and increasingly conscientious oil extraction activities.
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Affiliation(s)
- César Paz-y-Miño
- Instituto de Investigaciones Biomédicas, Facultad de Ciencias de la Salud, Universidad de las Américas, Ave. de los Granados y Colimes Quito, 1712842, Ecuador
| | - Nadia Cumbal
- Instituto de Investigaciones Biomédicas, Facultad de Ciencias de la Salud, Universidad de las Américas, Ave. de los Granados y Colimes Quito, 1712842, Ecuador
| | - María Eugenia Sánchez
- Instituto de Investigaciones Biomédicas, Facultad de Ciencias de la Salud, Universidad de las Américas, Ave. de los Granados y Colimes Quito, 1712842, Ecuador
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Menicali E, Moretti S, Voce P, Romagnoli S, Avenia N, Puxeddu E. Intracellular signal transduction and modification of the tumor microenvironment induced by RET/PTCs in papillary thyroid carcinoma. Front Endocrinol (Lausanne) 2012; 3:67. [PMID: 22661970 PMCID: PMC3357465 DOI: 10.3389/fendo.2012.00067] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2012] [Accepted: 04/30/2012] [Indexed: 01/06/2023] Open
Abstract
RET gene rearrangements (RET/PTCs) represent together with BRAF point mutations the two major groups of mutations involved in papillary thyroid carcinoma (PTC) initiation and progression. In this review, we will examine the mechanisms involved in RET/PTC-induced thyroid cell transformation. In detail, we will summarize the data on the molecular mechanisms involved in RET/PTC formation and in its function as a dominant oncogene, on the activated signal transduction pathways and on the induced gene expression modifications. Moreover, we will report on the effects of RET/PTCs on the tumor microenvironment. Finally, a short review of the literature on RET/PTC prognostic significance will be presented.
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Affiliation(s)
- Elisa Menicali
- Dipartimento di Medicina, University of PerugiaPerugia, Italy
- Centro di Proteomica e Genomica della Tiroide, University of PerugiaPerugia and Terni, Italy
| | - Sonia Moretti
- Dipartimento di Medicina, University of PerugiaPerugia, Italy
- Centro di Proteomica e Genomica della Tiroide, University of PerugiaPerugia and Terni, Italy
| | - Pasquale Voce
- Dipartimento di Medicina, University of PerugiaPerugia, Italy
- Centro di Proteomica e Genomica della Tiroide, University of PerugiaPerugia and Terni, Italy
| | | | - Nicola Avenia
- Centro di Proteomica e Genomica della Tiroide, University of PerugiaPerugia and Terni, Italy
- Dipartimento di Chirurgia, University of PerugiaPerugia, Italy
| | - Efisio Puxeddu
- Dipartimento di Medicina, University of PerugiaPerugia, Italy
- Centro di Proteomica e Genomica della Tiroide, University of PerugiaPerugia and Terni, Italy
- *Correspondence: Efisio Puxeddu, Dipartimento di Medicina, Sezione MIENDO, Via Enrico dal Pozzo – Padiglione X, 06126 Perugia, Italy. e-mail:
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Stewart RD, Yu VK, Georgakilas AG, Koumenis C, Park JH, Carlson DJ. Effects of Radiation Quality and Oxygen on Clustered DNA Lesions and Cell Death. Radiat Res 2011; 176:587-602. [DOI: 10.1667/rr2663.1] [Citation(s) in RCA: 150] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Gandhi M, Evdokimova V, Nikiforov YE. Mechanisms of chromosomal rearrangements in solid tumors: the model of papillary thyroid carcinoma. Mol Cell Endocrinol 2010; 321:36-43. [PMID: 19766698 PMCID: PMC2849910 DOI: 10.1016/j.mce.2009.09.013] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2009] [Revised: 09/07/2009] [Accepted: 09/10/2009] [Indexed: 11/24/2022]
Abstract
Thyroid cancer, and its most common type, papillary carcinoma, frequently have chromosomal rearrangements and therefore represent a good model for the understanding of mechanisms of chromosomal rearrangements in solid tumors. Several types of rearrangement known to occur in thyroid cancer, including RET/PTC, NTRK1 and BRAF/AKAP9, are more common in radiation-associated thyroid tumors and RET/PTC can be induced experimentally by exposing human thyroid cells to ionizing radiation. In this review, the molecular mechanisms of generation of RET/PTC and other chromosomal rearrangements are discussed, with the emphasis on the role of nuclear architecture and interphase gene proximity in the generation of intrachromosomal rearrangements in thyroid cells.
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Affiliation(s)
| | | | - Yuri E. Nikiforov
- Corresponding author: Dr. Yuri Nikiforov, Department of Pathology, University of Pittsburgh, 200 Lothrop Street, PUH, Room C-606, Pittsburgh, PA 15213, Telephone: 412-802-6083, Fax: 412-802-6799,
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Gudowska-Nowak E, Psonka-Antończyk K, Weron K, Elsässer T, Taucher-Scholz G. Distribution of DNA fragment sizes after irradiation with ions. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2009; 30:317-324. [PMID: 19823885 DOI: 10.1140/epje/i2009-10522-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2009] [Revised: 09/09/2009] [Accepted: 09/18/2009] [Indexed: 05/28/2023]
Abstract
Ionizing radiation is responsible for production of double-strand breaks (DSBs) in a DNA structure. In contrast to sparsely ionizing radiation, densely ionizing radiation produces DSBs that are non-randomly distributed along the DNA molecule and can form clusters of various size. The paper discusses minimalistic models that describe observable patterns of fragment length in DNA segments irradiated with heavy ions and applies the formalism to interpret the recent experimental data collected by use of atomic force microscope (AFM).
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Affiliation(s)
- E Gudowska-Nowak
- Marian Smoluchowski Institute of Physics, Jagellonian University, Kraków, Poland.
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Pai DA, Engelke DR. Spatial organization of genes as a component of regulated expression. Chromosoma 2009; 119:13-25. [PMID: 19727792 DOI: 10.1007/s00412-009-0236-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2009] [Revised: 08/05/2009] [Accepted: 08/06/2009] [Indexed: 12/15/2022]
Abstract
The DNA of living cells is highly compacted. Inherent in this spatial constraint is the need for cells to organize individual genetic loci so as to facilitate orderly retrieval of information. Complex genetic regulatory mechanisms are crucial to all organisms, and it is becoming increasingly evident that spatial organization of genes is one very important mode of regulation for many groups of genes. In eukaryotic nuclei, it appears not only that DNA is organized in three-dimensional space but also that this organization is dynamic and interactive with the transcriptional state of the genes. Spatial organization occurs throughout evolution and with genes transcribed by all classes of RNA polymerases in all eukaryotic nuclei, from yeast to human. There is an increasing body of work examining the ways in which this organization and consequent regulation are accomplished. In this review, we discuss the diverse strategies that cells use to preferentially localize various classes of genes.
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Affiliation(s)
- Dave A Pai
- Department of Biological Chemistry, University of Michigan, 1150 W. Medical Center Dr., Ann Arbor, MI, 48109-0606, USA
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Plan Y, Hlatky L, Hahnfeldt P, Sachs R, Loucas B, Cornforth M. Full-color painting reveals an excess of radiation-induced dicentrics involving homologous chromosomes. Int J Radiat Biol 2009; 81:613-20. [PMID: 16298942 DOI: 10.1080/09553000500331881] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
PURPOSE To determine the ratio of homologous to heterologous dicentric chromosomes induced in human cells by ionizing radiation. This ratio is influenced by, and thus potentially informative about, underlying DNA damage/repair/misrepair processes and also the geometry of individual chromosome domains within the interphase nucleus. MATERIALS AND METHODS 24-color mFISH (multiplex fluorescent in situ hybridization) was used to determine the ratio of 1-color (homologous) to 2-color (heterologous) dicentrics produced in human lymphocytes or fibroblasts by gamma-rays, alpha particles, or iron ions at various doses. Assuming that randomness independent of homology holds, the expected homologue:heterologue ratio for diploid human male cells is approximately 0.024, as shown by deriving a formula applicable to simple interchanges and then extending the result, via Monte Carlo simulation, to the general situation where complex aberrations are also considered. RESULTS AND CONCLUSIONS There was a substantial excess of homologous dicentrics, with probability of occurrence by chance less than 0.02 for each of the three radiations and only about 10(-8) for all the data combined. Overall, approximately 18 homologous dicentrics were expected but 47 were found, including 11 involving chromosome 1. Observed excesses were similar for both sparsely and densely ionizing radiations. Geometric proximity of homologues is a possible explanation for the overabundance; in that case more extensive statistics should eventually uncover a linear energy transfer (LET) dependence. An alternative possibility, not ruled out by the present data, is homology-dependent misrepair.
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Affiliation(s)
- Y Plan
- Department of Mathematics, University of California, Berkeley, CA, USA
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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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Live cell microscopy analysis of radiation-induced DNA double-strand break motion. Proc Natl Acad Sci U S A 2009; 106:3172-7. [PMID: 19221031 DOI: 10.1073/pnas.0810987106] [Citation(s) in RCA: 146] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
We studied the spatiotemporal organization of DNA damage processing by live cell microscopy analysis in human cells. In unirradiated U2OS osteosarcoma and HeLa cancer cells, a fast confined and Brownian-like motion of DNA repair protein foci was observed, which was not altered by radiation. By analyzing the motional activity of GFP-53BP1 foci in live cells up to 12-h after irradiation, we detected an additional slower mobility of damaged chromatin sites showing a mean square displacement of approximately 0.6 microm(2)/h after exposure to densely- or sparsely-ionizing radiation, most likely driven by normal diffusion of chromatin. Only occasionally, larger translational motion connected to morphological changes of the whole nucleus could be observed. In addition, there was no general tendency to form repair clusters in the irradiated cells. We conclude that long-range displacements of damaged chromatin domains do not generally occur during DNA double-strand break repair after introduction of multiple damaged sites by charged particles. The occasional and in part transient appearance of cluster formation of radiation-induced foci may represent a higher mobility of chromatin along the ion trajectory. These observations support the hypothesis that spatial proximity of DNA breaks is required for the formation of radiation-induced chromosomal exchanges.
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Lebbar A, Callier P, Baverel F, Marle N, Patrat C, Le Tessier D, Mugneret F, Dupont JM. Two cases of mosaicism for complex chromosome rearrangements (CCRM) associated with secondary infertility. Am J Med Genet A 2008; 146A:2651-6. [DOI: 10.1002/ajmg.a.32499] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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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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