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Affandi T, Haas A, Ohm AM, Wright GM, Black JC, Reyland ME. PKCδ Regulates Chromatin Remodeling and DNA Repair through SIRT6. Mol Cancer Res 2024; 22:181-196. [PMID: 37889141 PMCID: PMC10872792 DOI: 10.1158/1541-7786.mcr-23-0493] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 09/07/2023] [Accepted: 10/25/2023] [Indexed: 10/28/2023]
Abstract
Irradiation (IR) is a highly effective cancer therapy; however, IR damage to tumor-adjacent healthy tissues can result in significant comorbidities and potentially limit the course of therapy. We have previously shown that protein kinase C delta (PKCδ) is required for IR-induced apoptosis and that inhibition of PKCδ activity provides radioprotection in vivo. Here we show that PKCδ regulates histone modification, chromatin accessibility, and double-stranded break (DSB) repair through a mechanism that requires Sirtuin 6 (SIRT6). Overexpression of PKCδ promotes genomic instability and increases DNA damage and apoptosis. Conversely, depletion of PKCδ increases DNA repair via nonhomologous end joining (NHEJ) and homologous recombination (HR) as evidenced by increased formation of DNA damage foci, increased expression of DNA repair proteins, and increased repair of NHEJ and HR fluorescent reporter constructs. Nuclease sensitivity indicates that PKCδ depletion is associated with more open chromatin, while overexpression of PKCδ reduces chromatin accessibility. Epiproteome analysis reveals increased chromatin associated H3K36me2 in PKCδ-depleted cells which is accompanied by chromatin disassociation of KDM2A. We identify SIRT6 as a downstream mediator of PKCδ. PKCδ-depleted cells have increased SIRT6 expression, and depletion of SIRT6 reverses changes in chromatin accessibility, histone modification and DSB repair in PKCδ-depleted cells. Furthermore, depletion of SIRT6 reverses radioprotection in PKCδ-depleted cells. Our studies describe a novel pathway whereby PKCδ orchestrates SIRT6-dependent changes in chromatin accessibility to regulate DNA repair, and define a mechanism for regulation of radiation-induced apoptosis by PKCδ. IMPLICATIONS PKCδ controls sensitivity to irradiation by regulating DNA repair.
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Affiliation(s)
- Trisiani Affandi
- Department of Craniofacial Biology, School of Dental Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Ami Haas
- Department of Craniofacial Biology, School of Dental Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Angela M. Ohm
- Department of Craniofacial Biology, School of Dental Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Gregory M. Wright
- Department of Pharmacology, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Joshua C. Black
- Department of Pharmacology, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Mary E. Reyland
- Department of Craniofacial Biology, School of Dental Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
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Affandi T, Haas A, Ohm AM, Wright GM, Black JC, Reyland ME. PKCδ regulates chromatin remodeling and DNA repair through SIRT6. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.24.541991. [PMID: 37292592 PMCID: PMC10245827 DOI: 10.1101/2023.05.24.541991] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Protein kinase C delta (PKCδ) is a ubiquitous kinase whose function is defined in part by localization to specific cellular compartments. Nuclear PKCδ is both necessary and sufficient for IR-induced apoptosis, while inhibition of PKCδ activity provides radioprotection in vivo. How nuclear PKCδ regulates DNA-damage induced cell death is poorly understood. Here we show that PKCδ regulates histone modification, chromatin accessibility, and double stranded break (DSB) repair through a mechanism that requires SIRT6. Overexpression of PKCδ promotes genomic instability and increases DNA damage and apoptosis. Conversely, depletion of PKCδ increases DNA repair via non-homologous end joining (NHEJ) and homologous recombination (HR) as evidenced by more rapid formation of NHEJ (DNA-PK) and HR (Rad51) DNA damage foci, increased expression of repair proteins, and increased repair of NHEJ and HR fluorescent reporter constructs. Nuclease sensitivity indicates that PKCδ depletion is associated with more open chromatin, while overexpression of PKCδ reduces chromatin accessibility. Epiproteome analysis revealed that PKCδ depletion increases chromatin associated H3K36me2, and reduces ribosylation of KDM2A and chromatin bound KDM2A. We identify SIRT6 as a downstream mediator of PKCδ. PKCδ-depleted cells have increased expression of SIRT6, and depletion of SIRT6 reverses the changes in chromatin accessibility, histone modification and NHEJ and HR DNA repair seen with PKCδ-depletion. Furthermore, depletion of SIRT6 reverses radioprotection in PKCδ-depleted cells. Our studies describe a novel pathway whereby PKCδ orchestrates SIRT6-dependent changes in chromatin accessibility to increase DNA repair, and define a mechanism for regulation of radiation-induced apoptosis by PKCδ.
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Affiliation(s)
- Trisiani Affandi
- Department of Craniofacial Biology, School of Dental Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Ami Haas
- Department of Craniofacial Biology, School of Dental Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Angela M. Ohm
- Department of Craniofacial Biology, School of Dental Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Gregory M. Wright
- Department of Pharmacology, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Joshua C. Black
- Department of Pharmacology, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Mary E. Reyland
- Department of Craniofacial Biology, School of Dental Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
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3
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Gelova SP, Chan K. Mutagenesis induced by protonation of single-stranded DNA is linked to glycolytic sugar metabolism. Mutat Res 2023; 826:111814. [PMID: 36634476 DOI: 10.1016/j.mrfmmm.2023.111814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2022] [Revised: 12/29/2022] [Accepted: 01/04/2023] [Indexed: 01/09/2023]
Abstract
Mutagenesis can be thought of as random, in the sense that the occurrence of each mutational event cannot be predicted with precision in space or time. However, when sufficiently large numbers of mutations are analyzed, recurrent patterns of base changes called mutational signatures can be identified. To date, some 60 single base substitution or SBS signatures have been derived from analysis of cancer genomics data. We recently reported that the ubiquitous signature SBS5 matches the pattern of single nucleotide polymorphisms (SNPs) in humans and has analogs in many species. Using a temperature-sensitive single-stranded DNA (ssDNA) mutation reporter system, we also showed that a similar mutational pattern in yeast is dependent on error-prone translesion DNA synthesis (TLS) and glycolytic sugar metabolism. Here, we further investigated mechanisms that are responsible for this form of mutagenesis in yeast. We first confirmed that excess sugar metabolism leads to increased mutation rate, which was detectable by fluctuation assay. Since glycolysis is known to produce excess protons, we then investigated the effects of experimental manipulations on pH and mutagenesis. We hypothesized that yeast metabolizing 8% glucose would produce more excess protons than cells metabolizing 2% glucose. Consistent with this, cells metabolizing 8% glucose had lower intracellular and extracellular pH values. Similarly, deletion of vma3 (encoding a vacuolar H+-ATPase subunit) increased mutagenesis. We also found that treating cells with edelfosine (which renders membranes more permeable, including to protons) or culturing in low pH media increased mutagenesis. Analysis of the mutational pattern attributable to 20 µM edelfosine treatment revealed similarity to the SBS5-like TLS- and glycolysis-dependant mutational patterns previously observed in ssDNA. Altogether, our results agree with multiple biochemical studies showing that protonation of nitrogenous bases can alter base pairing so as to stabilize some mispairs, and shed new light on a common form of intrinsic mutagenesis.
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Affiliation(s)
- Suzana P Gelova
- University of Ottawa Faculty of Medicine, Department of Biochemistry, Microbiology and Immunology, Ottawa Institute of Systems Biology, 451 Smyth Road, Ottawa, Ontario K1H 8M5, Canada; Agriculture and Agri-Food Canada, 2585 County Road 20, Harrow, Ontario N0R 1G0, Canada
| | - Kin Chan
- University of Ottawa Faculty of Medicine, Department of Biochemistry, Microbiology and Immunology, Ottawa Institute of Systems Biology, 451 Smyth Road, Ottawa, Ontario K1H 8M5, Canada.
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Sánchez AG, Ibargoyen MN, Mastrogiovanni M, Radi R, Keszenman DJ, Peluffo RD. Fast and biphasic 8-nitroguanine production from guanine and peroxynitrite. Free Radic Biol Med 2022; 193:474-484. [PMID: 36332879 DOI: 10.1016/j.freeradbiomed.2022.10.317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 10/12/2022] [Accepted: 10/28/2022] [Indexed: 11/06/2022]
Abstract
Guanine (Gua), among purines, is a preferred oxidation/nitration target because of its low one-electron redox potential. The reactive oxygen/nitrogen species peroxynitrite (ONOO-), produced in vivo by the reaction between nitric oxide (•NO) and superoxide radical (O2•‒), is responsible for several oxidative modifications in biomolecules, including nitration, nitrosation, oxidation, and peroxidation. In particular, the nitration of Gua, although detected, as well as its reaction kinetics have been seldom investigated. Thus, we studied the concentration- and temperature-dependent formation of 8-nitroguanine (8-NitroGua) in phosphate buffer (pH 7.40) using stopped-flow spectrophotometry. Traces showed a biexponential behavior, with best-fit rate constants: kfast = 4.4 s-1 and kslow = 0.41 s-1 (30 °C, 400 μM both Gua and ONOO-). kfast increased linearly with the concentration of both reactants whereas kslow was concentration-independent. Linear regression analysis of kfast as a function of Gua and ONOO- concentration yielded values of 2.5-6.3 × 103 M-1s-1 and 1.5-3.5 s-1 for the second-order (slope) and first-order (ordinate) rate constants, respectively (30 °C). Since ONOO- is a short-lived species, its decay kinetics was also taken into account for this analysis. The 8-NitroGua product was stable for at least 4 h, so no spontaneous denitration was observed. Stopped-flow assays using antioxidants and free-radical scavengers suggested a mixed direct/indirect reaction mechanism for 8-NitroGua formation. Gua nitration by ONOO- was also observed in the presence of physiologically relevant CO2 concentrations. The reaction product identity, its yield (∼4.2%, with 400 μM ONOO- and 200 μM Gua), and the reaction mechanism were unequivocally determined by HPLC-MS/MS experiments. In conclusion, 8-NitroGua production at physiologic pH reached significant levels in a few hundred milliseconds, suggesting that the process might be kinetically relevant in vivo and can likely cause permanent nitrative damage to DNA bases.
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Affiliation(s)
- Ana G Sánchez
- Grupo de Biofisicoquímica, Departamento de Ciencias Biológicas, CENUR Litoral Norte, Universidad de la República, Rivera 1350, 50000, Salto, Uruguay
| | - M Natalia Ibargoyen
- Grupo de Biofisicoquímica, Departamento de Ciencias Biológicas, CENUR Litoral Norte, Universidad de la República, Rivera 1350, 50000, Salto, Uruguay
| | - Mauricio Mastrogiovanni
- Centro de Investigaciones Biomédicas (CEINBIO), Facultad de Medicina, Universidad de la República, Avda. General Flores 2125, 11800, Montevideo, Uruguay
| | - Rafael Radi
- Centro de Investigaciones Biomédicas (CEINBIO), Facultad de Medicina, Universidad de la República, Avda. General Flores 2125, 11800, Montevideo, Uruguay
| | - Deborah J Keszenman
- Grupo de Biofisicoquímica, Departamento de Ciencias Biológicas, CENUR Litoral Norte, Universidad de la República, Rivera 1350, 50000, Salto, Uruguay
| | - R Daniel Peluffo
- Grupo de Biofisicoquímica, Departamento de Ciencias Biológicas, CENUR Litoral Norte, Universidad de la República, Rivera 1350, 50000, Salto, Uruguay; Centro de Investigaciones Biomédicas (CEINBIO), Facultad de Medicina, Universidad de la República, Avda. General Flores 2125, 11800, Montevideo, Uruguay; Department of Pharmacology, Physiology and Neuroscience, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Rutgers, The State University of New Jersey, 185 South Orange Avenue, Newark, NJ, 07103, USA.
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5
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Gelova SP, Doherty KN, Alasmar S, Chan K. Intrinsic base substitution patterns in diverse species reveal links to cancer and metabolism. Genetics 2022; 222:iyac144. [PMID: 36149294 PMCID: PMC9630983 DOI: 10.1093/genetics/iyac144] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Accepted: 09/07/2022] [Indexed: 11/12/2022] Open
Abstract
Analyses of large-scale cancer sequencing data have revealed that mutagenic processes can create distinctive patterns of base substitutions, called mutational signatures. Interestingly, mutational patterns resembling some of these signatures can also be observed in normal cells. To determine whether similar patterns exist more generally, we analyzed large data sets of genetic variation, including mutations from 7 model species and single nucleotide polymorphisms in 42 species, totaling >1.9 billion variants. We found that base substitution patterns for most species closely match single base substitution (SBS) mutational signature 5 in the Catalog of Somatic Mutations in Cancer (COSMIC) database. SBS5 is ubiquitous in cancers and also present in normal human cells, suggesting that similar patterns of genetic variation across so many species are likely due to conserved biochemistry. We investigated the mechanistic origins of the SBS5-like mutational pattern in Saccharomyces cerevisiae, and show that translesion DNA synthesis and sugar metabolism are directly linked to this form of mutagenesis. We propose that conserved metabolic processes in cells are coupled to continuous generation of genetic variants, which can be acted upon by selection to drive the evolution of biological entities.
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Affiliation(s)
- Suzana P Gelova
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Kassidy N Doherty
- Biopharmaceutical Sciences Undergraduate Program, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Salma Alasmar
- Biopharmaceutical Sciences Undergraduate Program, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Kin Chan
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, ON K1H 8M5, Canada
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Thapa MJ, Fabros RM, Alasmar S, Chan K. Analyses of mutational patterns induced by formaldehyde and acetaldehyde reveal similarity to a common mutational signature. G3 GENES|GENOMES|GENETICS 2022; 12:6694047. [PMID: 36073936 PMCID: PMC9635668 DOI: 10.1093/g3journal/jkac238] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 08/22/2022] [Indexed: 12/23/2022]
Abstract
Formaldehyde and acetaldehyde are reactive small molecules produced endogenously in cells as well as being environmental contaminants. Both of these small aldehydes are classified as human carcinogens, since they are known to damage DNA and exposure is linked to cancer incidence. However, the mutagenic properties of formaldehyde and acetaldehyde remain incompletely understood, at least in part because they are relatively weak mutagens. Here, we use a highly sensitive yeast genetic reporter system featuring controlled generation of long single-stranded DNA regions to show that both small aldehydes induced mutational patterns characterized by predominantly C/G → A/T, C/G → T/A, and T/A → C/G substitutions, each in similar proportions. We observed an excess of C/G → A/T transversions when compared to mock-treated controls. Many of these C/G → A/T transversions occurred at TC/GA motifs. Interestingly, the formaldehyde mutational pattern resembles single base substitution signature 40 from the Catalog of Somatic Mutations in Cancer. Single base substitution signature 40 is a mutational signature of unknown etiology. We also noted that acetaldehyde treatment caused an excess of deletion events longer than 4 bases while formaldehyde did not. This latter result could be another distinguishing feature between the mutational patterns of these simple aldehydes. These findings shed new light on the characteristics of 2 important, commonly occurring mutagens.
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Affiliation(s)
- Mahanish J Thapa
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa , Ottawa, ON K1H 8M5, Canada
- Ottawa Institute of Systems Biology, University of Ottawa , Ottawa, ON K1H 8M5, Canada
| | - Reena M Fabros
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa , Ottawa, ON K1H 8M5, Canada
- Ottawa Institute of Systems Biology, University of Ottawa , Ottawa, ON K1H 8M5, Canada
| | - Salma Alasmar
- Biopharmaceutical Sciences Undergraduate Program, University of Ottawa , Ottawa, ON K1N 6N5, Canada
| | - Kin Chan
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa , Ottawa, ON K1H 8M5, Canada
- Ottawa Institute of Systems Biology, University of Ottawa , Ottawa, ON K1H 8M5, Canada
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Balajee AS, Livingston GK, Escalona MB, Ryan TL, Goans RE, Iddins CJ. Cytogenetic follow-up studies on humans with internal and external exposure to ionizing radiation. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2021; 41:S578-S601. [PMID: 34233319 DOI: 10.1088/1361-6498/ac125a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Accepted: 07/07/2021] [Indexed: 06/13/2023]
Abstract
Cells exposed to ionizing radiation have a wide spectrum of DNA lesions that include DNA single-strand breaks, DNA double-strand breaks (DSBs), oxidative base damage and DNA-protein crosslinks. Among them, DSB is the most critical lesion, which when mis-repaired leads to unstable and stable chromosome aberrations. Currently, chromosome aberration analysis is the preferred method for biological monitoring of radiation-exposed humans. Stable chromosome aberrations, such as inversions and balanced translocations, persist in the peripheral blood lymphocytes of radiation-exposed humans for several years and, therefore, are potentially useful tools to prognosticate the health risks of radiation exposure, particularly in the hematopoietic system. In this review, we summarize the cytogenetic follow-up studies performed by REAC/TS (Radiation Emergency Assistance Center/Training site, Oak Ridge, USA) on humans exposed to internal and external radiation. In the light of our observations as well as the data existing in the literature, this review attempts to highlight the importance of follow-up studies for predicting the extent of genomic instability and its impact on delayed health risks in radiation-exposed victims.
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Affiliation(s)
- Adayabalam S Balajee
- Cytogenetic Biodosimetry Laboratory, Radiation Emergency Assistance Centre/Training Site, Oak Ridge Institute for Science and Education, Oak Ridge Associated Universities, Oak Ridge, TN, United States of America
| | - Gordon K Livingston
- Cytogenetic Biodosimetry Laboratory, Radiation Emergency Assistance Centre/Training Site, Oak Ridge Institute for Science and Education, Oak Ridge Associated Universities, Oak Ridge, TN, United States of America
| | - Maria B Escalona
- Cytogenetic Biodosimetry Laboratory, Radiation Emergency Assistance Centre/Training Site, Oak Ridge Institute for Science and Education, Oak Ridge Associated Universities, Oak Ridge, TN, United States of America
| | - Terri L Ryan
- Cytogenetic Biodosimetry Laboratory, Radiation Emergency Assistance Centre/Training Site, Oak Ridge Institute for Science and Education, Oak Ridge Associated Universities, Oak Ridge, TN, United States of America
| | - Ronald E Goans
- Cytogenetic Biodosimetry Laboratory, Radiation Emergency Assistance Centre/Training Site, Oak Ridge Institute for Science and Education, Oak Ridge Associated Universities, Oak Ridge, TN, United States of America
| | - Carol J Iddins
- Cytogenetic Biodosimetry Laboratory, Radiation Emergency Assistance Centre/Training Site, Oak Ridge Institute for Science and Education, Oak Ridge Associated Universities, Oak Ridge, TN, United States of America
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Mavragani IV, Nikitaki Z, Kalospyros SA, Georgakilas AG. Ionizing Radiation and Complex DNA Damage: From Prediction to Detection Challenges and Biological Significance. Cancers (Basel) 2019; 11:E1789. [PMID: 31739493 PMCID: PMC6895987 DOI: 10.3390/cancers11111789] [Citation(s) in RCA: 96] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 11/07/2019] [Accepted: 11/11/2019] [Indexed: 12/12/2022] Open
Abstract
Biological responses to ionizing radiation (IR) have been studied for many years, generally showing the dependence of these responses on the quality of radiation, i.e., the radiation particle type and energy, types of DNA damage, dose and dose rate, type of cells, etc. There is accumulating evidence on the pivotal role of complex (clustered) DNA damage towards the determination of the final biological or even clinical outcome after exposure to IR. In this review, we provide literature evidence about the significant role of damage clustering and advancements that have been made through the years in its detection and prediction using Monte Carlo (MC) simulations. We conclude that in the future, emphasis should be given to a better understanding of the mechanistic links between the induction of complex DNA damage, its processing, and systemic effects at the organism level, like genomic instability and immune responses.
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Affiliation(s)
| | | | | | - Alexandros G. Georgakilas
- DNA Damage Laboratory, Department of Physics, School of Applied Mathematical and Physical Sciences, National Technical University of Athens (NTUA), 15780 Athens, Greece
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Affiliation(s)
- Muhammad Torequl Islam
- Postgraduate Program in Biotechnology, Northeast Biotechnology Network (RENORBIO), Federal University of Piauí, Teresina (Paiui), Brazil
- Department of Pharmacy, Southern University Bangladesh, Chittagong (Mehedibag), Bangladesh
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