1
|
Abramenkovs A, Hariri M, Spiegelberg D, Nilsson S, Stenerlöw B. Ra-223 induces clustered DNA damage and inhibits cell survival in several prostate cancer cell lines. Transl Oncol 2022; 26:101543. [PMID: 36126563 PMCID: PMC9489499 DOI: 10.1016/j.tranon.2022.101543] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 09/05/2022] [Accepted: 09/13/2022] [Indexed: 10/24/2022] Open
Abstract
The bone-seeking radiopharmaceutical Xofigo (Radium-223 dichloride) has demonstrated both extended survival and palliative effects in treatment of bone metastases in prostate cancer. The alpha-particle emitter Ra-223, targets regions undergoing active bone remodeling and strongly binds to bone hydroxyapatite (HAp). However, the toxicity mechanism and properties of Ra-223 binding to hydroxyapatite are not fully understood. By exposing 2D and 3D (spheroid) prostate cancer cell models to free and HAp-bound Ra-223 we here studied cell toxicity, apoptosis and formation and repair of DNA double-strand breaks (DSBs). The rapid binding with a high affinity of Ra-223 to bone-like HAp structures was evident (KD= 19.2 × 10-18 M) and almost no dissociation was detected within 24 h. Importantly, there was no significant uptake of Ra-223 in cells. The Ra-223 alpha-particle decay produced track-like distributions of the DNA damage response proteins 53BP1 and ɣH2AX induced high amounts of clustered DSBs in prostate cancer cells and activated DSB repair through non-homologous end-joining (NHEJ). Ra-223 inhibited growth of prostate cancer cells, independent of cell type, and induced high levels of apoptosis. In summary, we suggest the high cell killing efficacy of the Ra-223 was attributed to the clustered DNA damaged sites induced by α-particles.
Collapse
Affiliation(s)
- Andris Abramenkovs
- Department of Immunology, Genetics and Pathology, Rudbeck Laboratory, Uppsala University, Uppsala SE-75185, Sweden
| | - Mehran Hariri
- Department of Immunology, Genetics and Pathology, Rudbeck Laboratory, Uppsala University, Uppsala SE-75185, Sweden.
| | - Diana Spiegelberg
- Department of Immunology, Genetics and Pathology, Rudbeck Laboratory, Uppsala University, Uppsala SE-75185, Sweden; Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
| | - Sten Nilsson
- Department of Oncology-Pathology, Karolinska Institute, Stockholm, Sweden
| | - Bo Stenerlöw
- Department of Immunology, Genetics and Pathology, Rudbeck Laboratory, Uppsala University, Uppsala SE-75185, Sweden.
| |
Collapse
|
2
|
Kolobynina KG, Rapp A, Cardoso MC. Chromatin Ubiquitination Guides DNA Double Strand Break Signaling and Repair. Front Cell Dev Biol 2022; 10:928113. [PMID: 35865631 PMCID: PMC9294282 DOI: 10.3389/fcell.2022.928113] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 06/16/2022] [Indexed: 11/13/2022] Open
Abstract
Chromatin is the context for all DNA-based molecular processes taking place in the cell nucleus. The initial chromatin structure at the site of the DNA damage determines both, lesion generation and subsequent activation of the DNA damage response (DDR) pathway. In turn, proceeding DDR changes the chromatin at the damaged site and across large fractions of the genome. Ubiquitination, besides phosphorylation and methylation, was characterized as an important chromatin post-translational modification (PTM) occurring at the DNA damage site and persisting during the duration of the DDR. Ubiquitination appears to function as a highly versatile “signal-response” network involving several types of players performing various functions. Here we discuss how ubiquitin modifiers fine-tune the DNA damage recognition and response and how the interaction with other chromatin modifications ensures cell survival.
Collapse
|
3
|
Nanodosimetric Calculations of Radiation-Induced DNA Damage in a New Nucleus Geometrical Model Based on the Isochore Theory. Int J Mol Sci 2022; 23:ijms23073770. [PMID: 35409128 PMCID: PMC8998209 DOI: 10.3390/ijms23073770] [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: 12/10/2021] [Revised: 03/23/2022] [Accepted: 03/28/2022] [Indexed: 11/16/2022] Open
Abstract
Double-strand breaks (DSBs) in nuclear DNA represents radiation-induced damage that has been identified as particularly deleterious. Calculating this damage using Monte Carlo track structure modeling could be a suitable indicator to better assess and anticipate the side-effects of radiation therapy. However, as already demonstrated in previous work, the geometrical description of the nucleus and the DNA content used in the simulation significantly influence damage calculations. Therefore, in order to obtain accurate results, this geometry must be as realistic as possible. In this study, a new geometrical model of an endothelial cell nucleus and DNA distribution according to the isochore theory are presented and used in a Monte Carlo simulation chain based on the Geant4-DNA toolkit. In this theory, heterochromatin and euchromatin compaction are distributed along the genome according to five different families (L1, L2, H1, H2, and H3). Each of these families is associated with a different hetero/euchromatin rate related to its compaction level. In order to compare the results with those obtained using a previous nuclear geometry, simulations were performed for protons with linear energy transfers (LETs) of 4.29 keV/µm, 19.51 keV/µm, and 43.25 keV/µm. The organization of the chromatin fibers at different compaction levels linked to isochore families increased the DSB yield by 6-10%, and it allowed the most affected part of the genome to be identified. These new results indicate that the genome core is more radiosensitive than the genome desert, with a 3-8% increase in damage depending on the LET. This work highlights the importance of using realistic distributions of chromatin compaction levels to calculate radio-induced damage using Monte Carlo simulation methods.
Collapse
|
4
|
Bertolet A, Ramos-Méndez J, Paganetti H, Schuemann J. The relation between microdosimetry and induction of direct damage to DNA by alpha particles. Phys Med Biol 2021; 66. [PMID: 34280910 DOI: 10.1088/1361-6560/ac15a5] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Accepted: 07/19/2021] [Indexed: 11/12/2022]
Abstract
In radiopharmaceutical treatmentsα-particles are employed to treat tumor cells. However, the mechanism that drives the biological effect induced is not well known. Being ionizing radiation,α-particles can affect biological organisms by producing damage to the DNA, either directly or indirectly. Following the principle that microdosimetry theory accounts for the stochastic way in which radiation deposits energy in sub-cellular sized volumes via physical collisions, we postulate that microdosimetry represents a reasonable framework to characterize the statistical nature of direct damage induction byα-particles to DNA. We used the TOPAS-nBio Monte Carlo package to simulate direct damage produced by monoenergetic alpha particles to different DNA structures. In separate simulations, we obtained the frequency-mean lineal energy (yF) and dose-mean lineal energy (yD) of microdosimetric distributions sampled with spherical sites of different sizes. The total number of DNA strand breaks, double strand breaks (DSBs) and complex strand breaks per track were quantified and presented as a function of eitheryForyD.The probability of interaction between a track and the DNA depends on how the base pairs are compacted. To characterize this variability on compactness, spherical sites of different size were used to match these probabilities of interaction, correlating the size-dependent specific energy (z) with the damage induced. The total number of DNA strand breaks per track was found to linearly correlate withyFandzFwhen using what we defined an effective volume as microdosimetric site, while the yield of DSB per unit dose linearly correlated withyDorzD,being larger for compacted than for unfolded DNA structures. The yield of complex breaks per unit dose exhibited a quadratic behavior with respect toyDand a greater difference among DNA compactness levels. Microdosimetric quantities correlate with the direct damage imparted on DNA.
Collapse
Affiliation(s)
- Alejandro Bertolet
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, United States of America
| | - José Ramos-Méndez
- Department of Radiation Oncology, University of California San Francisco, United States of America
| | - Harald Paganetti
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, United States of America
| | - Jan Schuemann
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, United States of America
| |
Collapse
|
5
|
Hausmann M, Falk M, Neitzel C, Hofmann A, Biswas A, Gier T, Falkova I, Heermann DW, Hildenbrand G. Elucidation of the Clustered Nano-Architecture of Radiation-Induced DNA Damage Sites and Surrounding Chromatin in Cancer Cells: A Single Molecule Localization Microscopy Approach. Int J Mol Sci 2021; 22:3636. [PMID: 33807337 PMCID: PMC8037797 DOI: 10.3390/ijms22073636] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 03/20/2021] [Accepted: 03/26/2021] [Indexed: 02/06/2023] Open
Abstract
In cancer therapy, the application of (fractionated) harsh radiation treatment is state of the art for many types of tumors. However, ionizing radiation is a "double-edged sword"-it can kill the tumor but can also promote the selection of radioresistant tumor cell clones or even initiate carcinogenesis in the normal irradiated tissue. Individualized radiotherapy would reduce these risks and boost the treatment, but its development requires a deep understanding of DNA damage and repair processes and the corresponding control mechanisms. DNA double strand breaks (DSBs) and their repair play a critical role in the cellular response to radiation. In previous years, it has become apparent that, beyond genetic and epigenetic determinants, the structural aspects of damaged chromatin (i.e., not only of DSBs themselves but also of the whole damage-surrounding chromatin domains) form another layer of complex DSB regulation. In the present article, we summarize the application of super-resolution single molecule localization microscopy (SMLM) for investigations of these structural aspects with emphasis on the relationship between the nano-architecture of radiation-induced repair foci (IRIFs), represented here by γH2AX foci, and their chromatin environment. Using irradiated HeLa cell cultures as an example, we show repair-dependent rearrangements of damaged chromatin and analyze the architecture of γH2AX repair clusters according to topological similarities. Although HeLa cells are known to have highly aberrant genomes, the topological similarity of γH2AX was high, indicating a functional, presumptively genome type-independent relevance of structural aspects in DSB repair. Remarkably, nano-scaled chromatin rearrangements during repair depended both on the chromatin domain type and the treatment. Based on these results, we demonstrate how the nano-architecture and topology of IRIFs and chromatin can be determined, point to the methodological relevance of SMLM, and discuss the consequences of the observed phenomena for the DSB repair network regulation or, for instance, radiation treatment outcomes.
Collapse
Affiliation(s)
- Michael Hausmann
- Kirchhoff Institute for Physics, Heidelberg University, 69120 Heidelberg, Germany; (C.N.); (A.B.); (T.G.); (G.H.)
| | - Martin Falk
- Institute of Biophysics, Czech Academy of Sciences, 612 65 Brno, Czech Republic;
| | - Charlotte Neitzel
- Kirchhoff Institute for Physics, Heidelberg University, 69120 Heidelberg, Germany; (C.N.); (A.B.); (T.G.); (G.H.)
| | - Andreas Hofmann
- Institute for Theoretical Physics, Heidelberg University, 69120 Heidelberg, Germany; (A.H.); (D.W.H.)
| | - Abin Biswas
- Kirchhoff Institute for Physics, Heidelberg University, 69120 Heidelberg, Germany; (C.N.); (A.B.); (T.G.); (G.H.)
| | - Theresa Gier
- Kirchhoff Institute for Physics, Heidelberg University, 69120 Heidelberg, Germany; (C.N.); (A.B.); (T.G.); (G.H.)
| | - Iva Falkova
- Institute of Biophysics, Czech Academy of Sciences, 612 65 Brno, Czech Republic;
| | - Dieter W. Heermann
- Institute for Theoretical Physics, Heidelberg University, 69120 Heidelberg, Germany; (A.H.); (D.W.H.)
| | - Georg Hildenbrand
- Kirchhoff Institute for Physics, Heidelberg University, 69120 Heidelberg, Germany; (C.N.); (A.B.); (T.G.); (G.H.)
| |
Collapse
|
6
|
Vítor AC, Huertas P, Legube G, de Almeida SF. Studying DNA Double-Strand Break Repair: An Ever-Growing Toolbox. Front Mol Biosci 2020; 7:24. [PMID: 32154266 PMCID: PMC7047327 DOI: 10.3389/fmolb.2020.00024] [Citation(s) in RCA: 90] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 02/04/2020] [Indexed: 12/29/2022] Open
Abstract
To ward off against the catastrophic consequences of persistent DNA double-strand breaks (DSBs), eukaryotic cells have developed a set of complex signaling networks that detect these DNA lesions, orchestrate cell cycle checkpoints and ultimately lead to their repair. Collectively, these signaling networks comprise the DNA damage response (DDR). The current knowledge of the molecular determinants and mechanistic details of the DDR owes greatly to the continuous development of ground-breaking experimental tools that couple the controlled induction of DSBs at distinct genomic positions with assays and reporters to investigate DNA repair pathways, their impact on other DNA-templated processes and the specific contribution of the chromatin environment. In this review, we present these tools, discuss their pros and cons and illustrate their contribution to our current understanding of the DDR.
Collapse
Affiliation(s)
- Alexandra C Vítor
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal
| | - Pablo Huertas
- Department of Genetics, University of Seville, Seville, Spain.,Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Seville, Spain
| | - Gaëlle Legube
- LBCMCP, Centre de Biologie Integrative (CBI), CNRS, Université de Toulouse, Toulouse, France
| | - Sérgio F de Almeida
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal
| |
Collapse
|
7
|
Lee BH, Wang CKC. A cell-by-cell Monte Carlo simulation for assessing radiation-induced DNA double strand breaks. Phys Med 2019; 62:140-151. [DOI: 10.1016/j.ejmp.2019.05.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Revised: 04/08/2019] [Accepted: 05/04/2019] [Indexed: 11/30/2022] Open
|
8
|
Tang N, Bueno M, Meylan S, Incerti S, Clairand I, Villagrasa C. SIMULATION OF EARLY RADIATION-INDUCED DNA DAMAGE ON DIFFERENT TYPES OF CELL NUCLEI. RADIATION PROTECTION DOSIMETRY 2019; 183:26-31. [PMID: 30535369 DOI: 10.1093/rpd/ncy237] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
This work presents a comparison of simulated early radiation-induced DNA damage represented by yields of double-strand breaks (DSB) in three different human cell nuclei geometries representing fibroblasts, lymphocytes and endothelial cells for protons and alpha particles of different energies and for different irradiation configurations. Each cell nucleus model includes a multi-scale description of the DNA target from the molecular level to the whole human genome representation (6 Gbp) in the G0/G1 phase of the cell cycle and was generated with the DnaFabric software. The three nuclei differ in shape, volume, and therefore DNA density. A calculation chain based on Geant4-DNA that takes into account the physical, physico-chemical and chemical stages was used to simulate the irradiation of the different cell nuclei. Results show an increase of DSB/primary/μm with an increase of DNA density and an increase of DSB/Gy/Gbp with an increase of the cell nucleus volume which indicates that the cell nucleus shape and size have an impact on early DNA damage, which may play a role in latter effects.
Collapse
Affiliation(s)
- Nicolas Tang
- IRSN, Institut de Radioprotection et de Sûreté Nucléaire, Fontenay aux Roses, France
| | - Marta Bueno
- IRSN, Institut de Radioprotection et de Sûreté Nucléaire, Fontenay aux Roses, France
| | | | - Sébastien Incerti
- Université de Bordeaux, CNRS/IN2P3, Centre d'Etudes Nucléaires de Bordeaux Gradignan, CENBG, chemin du solarium, Gradignan, France
| | - Isabelle Clairand
- IRSN, Institut de Radioprotection et de Sûreté Nucléaire, Fontenay aux Roses, France
| | - Carmen Villagrasa
- IRSN, Institut de Radioprotection et de Sûreté Nucléaire, Fontenay aux Roses, France
| |
Collapse
|
9
|
Tang N, Bueno M, Meylan S, Incerti S, Tran HN, Vaurijoux A, Gruel G, Villagrasa C. Influence of chromatin compaction on simulated early radiation-induced DNA damage using Geant4-DNA. Med Phys 2019; 46:1501-1511. [DOI: 10.1002/mp.13405] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 01/07/2019] [Accepted: 01/21/2019] [Indexed: 11/11/2022] Open
Affiliation(s)
- N. Tang
- IRSN; Institut de Radioprotection et de Sûreté Nucléaire; BP17 92262 Fontenay aux Roses France
| | - M. Bueno
- IRSN; Institut de Radioprotection et de Sûreté Nucléaire; BP17 92262 Fontenay aux Roses France
| | - S. Meylan
- SymAlgo Technologies; 75 rue Léon Frot 75011 Paris France
| | - S. Incerti
- Université de Bordeaux CNRS/IN2P3 Centre d'Etudes Nucléaires de Bordeaux; Gradignan CENBG; chemin du solarium, BP120 33175 Gradignan France
| | - H. N. Tran
- IRSN; Institut de Radioprotection et de Sûreté Nucléaire; BP17 92262 Fontenay aux Roses France
| | - A. Vaurijoux
- IRSN; Institut de Radioprotection et de Sûreté Nucléaire; BP17 92262 Fontenay aux Roses France
| | - G. Gruel
- IRSN; Institut de Radioprotection et de Sûreté Nucléaire; BP17 92262 Fontenay aux Roses France
| | - C. Villagrasa
- IRSN; Institut de Radioprotection et de Sûreté Nucléaire; BP17 92262 Fontenay aux Roses France
| |
Collapse
|
10
|
Cannan WJ, Pederson DS. Mechanisms and Consequences of Double-Strand DNA Break Formation in Chromatin. J Cell Physiol 2016; 231:3-14. [PMID: 26040249 DOI: 10.1002/jcp.25048] [Citation(s) in RCA: 245] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2015] [Accepted: 05/14/2015] [Indexed: 12/14/2022]
Abstract
All organisms suffer double-strand breaks (DSBs) in their DNA as a result of exposure to ionizing radiation. DSBs can also form when replication forks encounter DNA lesions or repair intermediates. The processing and repair of DSBs can lead to mutations, loss of heterozygosity, and chromosome rearrangements that result in cell death or cancer. The most common pathway used to repair DSBs in metazoans (non-homologous DNA end joining) is more commonly mutagenic than the alternative pathway (homologous recombination mediated repair). Thus, factors that influence the choice of pathways used DSB repair can affect an individual's mutation burden and risk of cancer. This review describes radiological, chemical, and biological mechanisms that generate DSBs, and discusses the impact of such variables as DSB etiology, cell type, cell cycle, and chromatin structure on the yield, distribution, and processing of DSBs. The final section focuses on nucleosome-specific mechanisms that influence DSB production, and the possible relationship between higher order chromosome coiling and chromosome shattering (chromothripsis).
Collapse
Affiliation(s)
- Wendy J Cannan
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont
| | - David S Pederson
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont
| |
Collapse
|
11
|
Effect of Chromatin Structure on the Extent and Distribution of DNA Double Strand Breaks Produced by Ionizing Radiation; Comparative Study of hESC and Differentiated Cells Lines. Int J Mol Sci 2016; 17:ijms17010058. [PMID: 26729112 PMCID: PMC4730303 DOI: 10.3390/ijms17010058] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Revised: 11/27/2015] [Accepted: 12/24/2015] [Indexed: 12/01/2022] Open
Abstract
Chromatin structure affects the extent of DNA damage and repair. Thus, it has been shown that heterochromatin is more protective against DNA double strand breaks (DSB) formation by ionizing radiation (IR); and that DNA DSB repair may proceed differently in hetero- and euchromatin regions. Human embryonic stem cells (hESC) have a more open chromatin structure than differentiated cells. Here, we study the effect of chromatin structure in hESC on initial DSB formation and subsequent DSB repair. DSB were scored by comet assay; and DSB repair was assessed by repair foci formation via 53BP1 antibody staining. We found that in hESC, heterochromatin is confined to distinct regions, while in differentiated cells it is distributed more evenly within the nuclei. The same dose of ionizing radiation produced considerably more DSB in hESC than in differentiated derivatives, normal human fibroblasts; and one cancer cell line. At the same time, the number of DNA repair foci were not statistically different among these cells. We showed that in hESC, DNA repair foci localized almost exclusively outside the heterochromatin regions. We also noticed that exposure to ionizing radiation resulted in an increase in heterochromatin marker H3K9me3 in cancer HT1080 cells, and to a lesser extent in IMR90 normal fibroblasts, but not in hESCs. These results demonstrate the importance of chromatin conformation for DNA protection and DNA damage repair; and indicate the difference of these processes in hESC.
Collapse
|
12
|
Berardinelli F, De Vitis M, Nieri D, Cherubini R, De Nadal V, Gerardi S, Tanzarella C, Sgura A, Antoccia A. mBAND and mFISH analysis of chromosomal aberrations and breakpoint distribution in chromosome 1 of AG01522 human fibroblasts that were exposed to radiation of different qualities. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2015; 793:55-63. [DOI: 10.1016/j.mrgentox.2015.05.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Accepted: 05/27/2015] [Indexed: 11/26/2022]
|
13
|
Gustafsson AS, Hartman T, Stenerlöw B. Formation and repair of clustered damaged DNA sites in high LET irradiated cells. Int J Radiat Biol 2015; 91:820-6. [DOI: 10.3109/09553002.2015.1068463] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
|
14
|
Huang YW, Pan CY, Hsiao YY, Chao TC, Lee CC, Tung CJ. Monte Carlo simulations of the relative biological effectiveness for DNA double strand breaks from 300 MeV u(-1) carbon-ion beams. Phys Med Biol 2015; 60:5995-6012. [PMID: 26183156 DOI: 10.1088/0031-9155/60/15/5995] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Monte Carlo simulations are used to calculate the relative biological effectiveness (RBE) of 300 MeV u(-1) carbon-ion beams at different depths in a cylindrical water phantom of 10 cm radius and 30 cm long. RBE values for the induction of DNA double strand breaks (DSB), a biological endpoint closely related to cell inactivation, are estimated for monoenergetic and energy-modulated carbon ion beams. Individual contributions to the RBE from primary ions and secondary nuclear fragments are simulated separately. These simulations are based on a multi-scale modelling approach by first applying the FLUKA (version 2011.2.17) transport code to estimate the absorbed doses and fluence energy spectra, then using the MCDS (version 3.10A) damage code for DSB yields. The approach is efficient since it separates the non-stochastic dosimetry problem from the stochastic DNA damage problem. The MCDS code predicts the major trends of the DSB yields from detailed track structure simulations. It is found that, as depth is increasing, RBE values increase slowly from the entrance depth to the plateau region and change substantially in the Bragg peak region. RBE values reach their maxima at the distal edge of the Bragg peak. Beyond this edge, contributions to RBE are entirely from nuclear fragments. Maximum RBE values at the distal edges of the Bragg peak and the spread-out Bragg peak are, respectively, 3.0 and 2.8. The present approach has the flexibility to weight RBE contributions from different DSB classes, i.e. DSB0, DSB+ and DSB++.
Collapse
Affiliation(s)
- Y W Huang
- Department of Medical Imaging and Radiological Sciences, College of Medicine, Chang Gung University, Kweishan Taoyuan, Taiwan
| | | | | | | | | | | |
Collapse
|
15
|
Tommasino F, Friedrich T, Jakob B, Meyer B, Durante M, Scholz M. Induction and Processing of the Radiation-Induced Gamma-H2AX Signal and Its Link to the Underlying Pattern of DSB: A Combined Experimental and Modelling Study. PLoS One 2015; 10:e0129416. [PMID: 26067661 PMCID: PMC4465900 DOI: 10.1371/journal.pone.0129416] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Accepted: 05/10/2015] [Indexed: 12/23/2022] Open
Abstract
We present here an analysis of DSB induction and processing after irradiation with X-rays in an extended dose range based on the use of the γH2AX assay. The study was performed by quantitative flow cytometry measurements, since the use of foci counting would result in reasonable accuracy only in a limited dose range of a few Gy. The experimental data are complemented by a theoretical analysis based on the GLOBLE model. In fact, original aim of the study was to test GLOBLE predictions against new experimental data, in order to contribute to the validation of the model. Specifically, the γH2AX signal kinetics has been investigated up to 24 h after exposure to increasing photon doses between 2 and 500 Gy. The prolonged persistence of the signal at high doses strongly suggests dose dependence in DSB processing after low LET irradiation. Importantly, in the framework of our modelling analysis, this is related to a gradually increased fraction of DSB clustering at the micrometre scale. The parallel study of γH2AX dose response curves shows the onset of a pronounced saturation in two cell lines at a dose of about 20 Gy. This dose is much lower than expected according to model predictions based on the values usually adopted for the DSB induction yield (≈ 30 DSB/Gy) and for the γH2AX foci extension of approximately 2 Mbp around the DSB. We show and discuss how theoretical predictions and experimental findings can be in principle reconciled by combining an increased DSB induction yield with the assumption of a larger genomic extension for the single phosphorylated regions. As an alternative approach, we also considered in our model the possibility of a 3D spreading-mechanism of the H2AX phosphorylation around the induced DSB, and applied it to the analysis of both the aspects considered. Our results are found to be supportive for the basic assumptions on which GLOBLE is built. Apart from giving new insights into the H2AX phosphorylation process, experiments performed at high doses are of relevance in the context of radiation therapy, where hypo-fractionated schemes become increasingly popular.
Collapse
Affiliation(s)
- Francesco Tommasino
- GSI Helmholtzzentrum für Schwerionenforschung, Department of Biophysics, Darmstadt, Germany
- * E-mail:
| | - Thomas Friedrich
- GSI Helmholtzzentrum für Schwerionenforschung, Department of Biophysics, Darmstadt, Germany
| | - Burkhard Jakob
- GSI Helmholtzzentrum für Schwerionenforschung, Department of Biophysics, Darmstadt, Germany
| | - Barbara Meyer
- GSI Helmholtzzentrum für Schwerionenforschung, Department of Biophysics, Darmstadt, Germany
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Marco Durante
- GSI Helmholtzzentrum für Schwerionenforschung, Department of Biophysics, Darmstadt, Germany
- Technische Universität Darmstadt, Institut für Festkörperphysik, Darmstadt, Germany
| | - Michael Scholz
- GSI Helmholtzzentrum für Schwerionenforschung, Department of Biophysics, Darmstadt, Germany
| |
Collapse
|
16
|
The repair of environmentally relevant DNA double strand breaks caused by high linear energy transfer irradiation – No simple task. DNA Repair (Amst) 2014; 17:64-73. [DOI: 10.1016/j.dnarep.2014.01.014] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 01/10/2014] [Accepted: 01/24/2014] [Indexed: 01/03/2023]
|
17
|
Ponomarev AL, George K, Cucinotta FA. Generalized time-dependent model of radiation-induced chromosomal aberrations in normal and repair-deficient human cells. Radiat Res 2014; 181:284-92. [PMID: 24611656 DOI: 10.1667/rr13303.1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
We have developed a model that can simulate the yield of radiation-induced chromosomal aberrations (CAs) and unrejoined chromosome breaks in normal and repair-deficient cells. The model predicts the kinetics of chromosomal aberration formation after exposure in the G₀/G₁ phase of the cell cycle to either low- or high-LET radiation. A previously formulated model based on a stochastic Monte Carlo approach was updated to consider the time dependence of DNA double-strand break (DSB) repair (proper or improper), and different cell types were assigned different kinetics of DSB repair. The distribution of the DSB free ends was derived from a mechanistic model that takes into account the structure of chromatin and DSB clustering from high-LET radiation. The kinetics of chromosomal aberration formation were derived from experimental data on DSB repair kinetics in normal and repair-deficient cell lines. We assessed different types of chromosomal aberrations with the focus on simple and complex exchanges, and predicted the DSB rejoining kinetics and misrepair probabilities for different cell types. The results identify major cell-dependent factors, such as a greater yield of chromosome misrepair in ataxia telangiectasia (AT) cells and slower rejoining in Nijmegen (NBS) cells relative to the wild-type. The model's predictions suggest that two mechanisms could exist for the inefficiency of DSB repair in AT and NBS cells, one that depends on the overall speed of joining (either proper or improper) of DNA broken ends, and another that depends on geometric factors, such as the Euclidian distance between DNA broken ends, which influences the relative frequency of misrepair.
Collapse
Affiliation(s)
- Artem L Ponomarev
- a Division of Space Life Sciences, Universities Space Research Association, Houston, Texas 77058
| | | | | |
Collapse
|
18
|
Lavelle C, Foray N. Chromatin structure and radiation-induced DNA damage: from structural biology to radiobiology. Int J Biochem Cell Biol 2014; 49:84-97. [PMID: 24486235 DOI: 10.1016/j.biocel.2014.01.012] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Revised: 01/13/2014] [Accepted: 01/18/2014] [Indexed: 10/25/2022]
Abstract
Genomic DNA in eukaryotic cells is basically divided into chromosomes, each consisting of a single huge nucleosomal fiber. It is now clear that chromatin structure and dynamics play a critical role in all processes involved in DNA metabolism, e.g. replication, transcription, repair and recombination. Radiation is a useful tool to study the biological effects of chromatin alterations. Conversely, radiotherapy and radiodiagnosis raise questions about the influence of chromatin integrity on clinical features and secondary effects. This review focuses on the link between DNA damage and chromatin structure at different scales, showing how a comprehensive multiscale vision is required to understand better the effect of radiations on DNA. Clinical aspects related to high- and low-dose of radiation and chromosomal instability will be discussed. At the same time, we will show that the analysis of the radiation-induced DNA damage distribution provides good insight on chromatin structure. Hence, we argue that chromatin "structuralists" and radiobiological "clinicians" would each benefit from more collaboration with the other. We hope that this focused review will help in this regard.
Collapse
Affiliation(s)
- Christophe Lavelle
- Genome Structure and Instability, National Museum of Natural History, Paris, France; CNRS UMR7196, Paris, France; INSERM U1154, Paris, France; Nuclear Architecture and Dynamics, CNRS GDR 3536, Paris, France.
| | - Nicolas Foray
- Nuclear Architecture and Dynamics, CNRS GDR 3536, Paris, France; INSERM, UMR1052, Radiobiology Group, Cancer Research Centre of Lyon, Lyon, France
| |
Collapse
|
19
|
Tommasino F, Friedrich T, Scholz U, Taucher-Scholz G, Durante M, Scholz M. A DNA Double-Strand Break Kinetic Rejoining Model Based on the Local Effect Model. Radiat Res 2013; 180:524-38. [DOI: 10.1667/rr13389.1] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
|
20
|
Morano A, Angrisano T, Russo G, Landi R, Pezone A, Bartollino S, Zuchegna C, Babbio F, Bonapace IM, Allen B, Muller MT, Chiariotti L, Gottesman ME, Porcellini A, Avvedimento EV. Targeted DNA methylation by homology-directed repair in mammalian cells. Transcription reshapes methylation on the repaired gene. Nucleic Acids Res 2013; 42:804-21. [PMID: 24137009 PMCID: PMC3902918 DOI: 10.1093/nar/gkt920] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
We report that homology-directed repair of a DNA double-strand break within a single copy Green Fluorescent Protein (GFP) gene in HeLa cells alters the methylation pattern at the site of recombination. DNA methyl transferase (DNMT)1, DNMT3a and two proteins that regulate methylation, Np95 and GADD45A, are recruited to the site of repair and are responsible for selective methylation of the promoter-distal segment of the repaired DNA. The initial methylation pattern of the locus is modified in a transcription-dependent fashion during the 15–20 days following repair, at which time no further changes in the methylation pattern occur. The variation in DNA modification generates stable clones with wide ranges of GFP expression. Collectively, our data indicate that somatic DNA methylation follows homologous repair and is subjected to remodeling by local transcription in a discrete time window during and after the damage. We propose that DNA methylation of repaired genes represents a DNA damage code and is source of variation of gene expression.
Collapse
Affiliation(s)
- Annalisa Morano
- Dipartimento di Medicina Molecolare e Biotecnologie mediche, Istituto di Endocrinologia ed Oncologia Sperimentale del C.N.R., Università Federico II, 80131 Napoli, Italy, IRCCS CROB, Dipartimento di Oncologia Sperimentale, via Padre Pio, 1 85028 Rionero in Vulture, Italy, Dipartimento di Medicina e di Scienze della Salute, Università del Molise, 86100 Campobasso, Itay, Dipartimento di Biologia, Università Federico II, 80126 Napoli, Italy, Dipartimento di Biologia Strutturale e Funzionale, Università dell'Insubria, Varese 21100, Italy, Department of Molecular Biology and Microbiology and Biomolecular Science Center, University of Central Florida, 12722 Research Parkway, Orlando, FL 32826, USA and Institute of Cancer Research, Departments of Microbiology and Biochemistry and Molecular Biophysics, Columbia University Medical Center, New York, NY 10032, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
21
|
Bajinskis A, Natarajan AT, Erixon K, Harms-Ringdahl M. DNA double strand breaks induced by the indirect effect of radiation are more efficiently repaired by non-homologous end joining compared to homologous recombination repair. Mutat Res 2013; 756:21-9. [PMID: 23811167 DOI: 10.1016/j.mrgentox.2013.06.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Accepted: 06/18/2013] [Indexed: 11/19/2022]
Abstract
The aim of this study was to investigate the relative involvement of three major DNA repair pathways, i.e., non-homologous end joining (NHEJ), homologous recombination (HRR) and base excision (BER) in repair of DNA lesions of different complexity induced by low- or high-LET radiation with emphasis on the contribution of the indirect effect of radiation for these radiation qualities. A panel of DNA repair-deficient CHO cell lines was irradiated by (137)Cs γ-rays or radon progeny α-particles. Irradiation was also performed in the presence of 2M DMSO to reduce the indirect effect of radiation and the complexity of the DNA damage formed. Clonogenic survival and micronucleus assays were used to estimate efficiencies of the different repair pathways for DNA damages produced by direct and indirect effects. Removal of the indirect effect of low-LET radiation by DMSO increased clonogenic survival and decreased MN formation for all cell lines investigated. A direct contribution of the indirect effect of radiation to DNA base damage was suggested by the significant protection by DMSO seen for the BER deficient cell line. Lesions formed by the indirect effect are more readily repaired by the NHEJ pathway than by HRR after irradiation with γ-rays or α-particles as evaluated by cell survival and the yields of MN. The results obtained with BER- and NHEJ-deficient cells suggest that the indirect effect of radiation contributes significantly to the formation of repair substrates for these pathways.
Collapse
Affiliation(s)
- Ainars Bajinskis
- Centre for Radiation Protection Research, Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-106 91 Stockholm, Sweden; Faculty of Medicine, University of Latvia, LV-1586 Riga, Latvia.
| | | | | | | |
Collapse
|
22
|
Friedrich T, Durante M, Scholz M. Modeling Cell Survival after Photon Irradiation Based on Double-Strand Break Clustering in Megabase Pair Chromatin Loops. Radiat Res 2012; 178:385-94. [DOI: 10.1667/rr2964.1] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
|
23
|
Brassesco MS, Valera ET, Neder L, Pezuk JA, Oliveira RS, Scrideli CA, Tone LG. Cytogenetic findings in pediatric radiation-induced atypical meningioma after treatment of medulloblastoma: case report and review of the literature. J Neurooncol 2012; 110:397-402. [DOI: 10.1007/s11060-012-0982-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2012] [Accepted: 10/01/2012] [Indexed: 11/24/2022]
|
24
|
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]
|
25
|
Friedrich T, Scholz U, Elsässer T, Durante M, Scholz M. Calculation of the biological effects of ion beams based on the microscopic spatial damage distribution pattern. Int J Radiat Biol 2011; 88:103-7. [PMID: 21823820 DOI: 10.3109/09553002.2011.611213] [Citation(s) in RCA: 138] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE To present details of the recent version of the 'Local Effect Model' (LEM), that has been developed and implemented in treatment planning for the ion beam therapy pilot project performed at GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt, Germany. MATERIALS AND METHODS The new version of the model is based on a detailed consideration of the spatial distribution of the initial damages, i.e., double-strand breaks (DSB). This spatial distribution of DSB is obtained from the radial dose profile of the ion track using Monte Carlo methods. These distributions are then analyzed with regard to the proximity of DSB. This version of the model also facilitates the calculation of full dose response curves up to arbitrary high doses, thus allowing to thoroughly check the approximations previously used to estimate the quadratic term (β-term) for the linear-quadratic description of dose response curves. RESULTS The accuracy of the model predictions is demonstrated by good agreement of the relative biological effectiveness (RBE) as a function of the linear energy transfer (LET) with experimental data obtained for V79 cells after carbon irradiation. The β-values predicted by the full simulation tend to be larger as compared to the approximation in the intermediate LET range. CONCLUSION The new version of the model allows a more mechanistic description of the biological effects of ion radiation. The full simulation is a prerequisite for tests of the validity of the approach at high doses, which are of particular interest for application in hypofractionation studies.
Collapse
Affiliation(s)
- Thomas Friedrich
- GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany
| | | | | | | | | |
Collapse
|
26
|
Claesson K, Magnander K, Kahu H, Lindegren S, Hultborn R, Elmroth K. RBE of α-particles from211At for complex DNA damage and cell survival in relation to cell cycle position. Int J Radiat Biol 2010; 87:372-84. [DOI: 10.3109/09553002.2011.538127] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
|
27
|
|
28
|
Magnander K, Hultborn R, Claesson K, Elmroth K. Clustered DNA Damage in Irradiated Human Diploid Fibroblasts: Influence of Chromatin Organization. Radiat Res 2010; 173:272-82. [DOI: 10.1667/rr1891.1] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
|
29
|
Ståhl S, Fung E, Adams C, Lengqvist J, Mörk B, Stenerlöw B, Lewensohn R, Lehtiö J, Zubarev R, Viktorsson K. Proteomics and pathway analysis identifies JNK signaling as critical for high linear energy transfer radiation-induced apoptosis in non-small lung cancer cells. Mol Cell Proteomics 2009; 8:1117-29. [PMID: 19168796 DOI: 10.1074/mcp.m800274-mcp200] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
During the past decade, we have witnessed an explosive increase in generation of large proteomics data sets, not least in cancer research. There is a growing need to extract and correctly interpret information from such data sets to generate biologically relevant hypotheses. A pathway search engine (PSE) has recently been developed as a novel tool intended to meet these requirements. Ionizing radiation (IR) is an anticancer treatment modality that triggers multiple signal transduction networks. In this work, we show that high linear energy transfer (LET) IR induces apoptosis in a non-small cell lung cancer cell line, U-1810, whereas low LET IR does not. PSE was applied to study changes in pathway status between high and low LET IR to find pathway candidates of importance for high LET-induced apoptosis. Such pathways are potential clinical targets, and they were further validated in vitro. We used an unsupervised shotgun proteomics approach where high resolution mass spectrometry coupled to nanoflow liquid chromatography determined the identity and relative abundance of expressed proteins. Based on the proteomics data, PSE suggested the JNK pathway (p = 6.10(-6)) as a key event in response to high LET IR. In addition, the Fas pathway was found to be activated (p = 3.10(-5)) and the p38 pathway was found to be deactivated (p = 0.001) compared with untreated cells. Antibody-based analyses confirmed that high LET IR caused an increase in phosphorylation of JNK. Moreover pharmacological inhibition of JNK blocked high LET-induced apoptotic signaling. In contrast, neither an activation of p38 nor a role for p38 in high LET IR-induced apoptotic signaling was found. We conclude that, in contrast to conventional low LET IR, high LET IR can trigger activation of the JNK pathway, which in turn is critical for induction of apoptosis in these cells. Thus PSE predictions were largely confirmed, and PSE was proven to be a useful hypothesis-generating tool.
Collapse
Affiliation(s)
- Sara Ståhl
- Department of Oncology/Pathology, Karolinska Biomics Center, Karolinska Institutet, S-17176 Stockholm, Sweden
| | | | | | | | | | | | | | | | | | | |
Collapse
|
30
|
Karlsson KH, Radulescu I, Rydberg B, Stenerlöw B. Repair of radiation-induced heat-labile sites is independent of DNA-PKcs, XRCC1 and PARP. Radiat Res 2008; 169:506-12. [PMID: 18439038 DOI: 10.1667/rr1076.1] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2007] [Accepted: 12/28/2007] [Indexed: 11/03/2022]
Abstract
Ionizing radiation induces a variety of different DNA lesions; in addition to the most critical DNA damage, the DSB, numerous base alterations, SSBs and other modifications of the DNA double-helix are formed. When several non-DSB lesions are clustered within a short distance along DNA, or close to a DSB, they may interfere with the repair of DSBs and affect the measurement of DSB induction and repair. We have shown previously that a substantial fraction of DSBs measured by pulsed-field gel electrophoresis (PFGE) are in fact due to heat-labile sites within clustered lesions, thus reflecting an artifact of preparation of genomic DNA at elevated temperature. To further characterize the influence of heat-labile sites on DSB induction and repair, cells of four human cell lines (GM5758, GM7166, M059K, U-1810) with apparently normal DSB rejoining were tested for biphasic rejoining after gamma irradiation. When heat-released DSBs were excluded from the measurements, the fraction of fast rejoining decreased to less than 50% of the total. However, the half-times of the fast (t(1/2) = 7-8 min) and slow (t(1/2) = 2.5 h) DSB rejoining were not changed significantly. At t = 0, the heat-released DSBs accounted for almost 40% of the DSBs, corresponding to 10 extra DSBs per cell per Gy in the initial DSB yield. These heat-released DSBs were repaired within 60-90 min in all cells tested, including M059K cells treated with wortmannin and DNA-PKcs-defective M059J cells. Furthermore, cells lacking XRCC1 or poly(ADP-ribose) polymerase 1 (PARP1) rejoined both total DSBs and heat-released DSBs similarly to normal cells. In summary, the presence of heat-labile sites has a substantial impact on DSB induction and DSB rejoining rates measured by pulsed-field gel electrophoresis, and heat-labile sites repair is independent of DNA-PKcs, XRCC1 and PARP.
Collapse
Affiliation(s)
- Karin H Karlsson
- Division of Biomedical Radiation Sciences, Uppsala University, Uppsala, Sweden
| | | | | | | |
Collapse
|
31
|
Carlson DJ, Stewart RD, Semenenko VA, Sandison GA. Combined Use of Monte Carlo DNA Damage Simulations and Deterministic Repair Models to Examine Putative Mechanisms of Cell Killing. Radiat Res 2008; 169:447-59. [DOI: 10.1667/rr1046.1] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2007] [Accepted: 12/19/2007] [Indexed: 11/03/2022]
|
32
|
Elmroth K, Stenerlöw B. Influence of Chromatin Structure on Induction of Double-Strand Breaks in Mammalian Cells Irradiated with DNA-Incorporated125I. Radiat Res 2007; 168:175-82. [PMID: 17638403 DOI: 10.1667/rr0652.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2006] [Accepted: 03/26/2007] [Indexed: 11/03/2022]
Abstract
In this study the induction of double-strand breaks (DSBs) was investigated in Chinese hamster V79-379A cells irradiated with the Auger-electron emitter (125)I incorporated into DNA. The role of chromatin organization was studied by pulse-labeling synchronized cells with (125)IdU before decay accumulation in early or late S phase. Pulsed-field gel electrophoresis and fragment-size analysis were used to quantify the distribution of DNA fragments in irradiated intact cells and naked DNA as well as in DNA from asynchronously labeled cultures in a different scavenging environment. The results show that in intact cells, after accumulation of decays at -70 degrees C in the presence of 10% DMSO, almost four times more DSBs were induced in late S phase compared with early S phase and the fragment distribution was clearly non-random with an excess of fragments <0.2 Mbp. The DSB yield was 0.6 DSB/cell and decay for cells irradiated in early S phase and 2.3 DSBs/cell and decay for cells irradiated in late S phase. When similar experiments were performed on naked genomic DNA or intact cells irradiated with gamma rays, the difference in yield was not as prominent. These data imply a role of chromatin organization in the induction of DSBs by DNA-incorporated (125)I. In summary, the results presented here suggest that the yield of DSBs as well as the fragment distribution induced by (125)IdU decay may vary significantly depending on the chromatin organization during S phase and the labeling procedure used.
Collapse
|
33
|
Ponomarev AL, Belli M, Hahnfeldt PJ, Hlatky L, Sachs RK, Cucinotta FA. Subtraction of background damage in PFGE experiments on DNA fragment-size distributions. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2007; 46:155-60. [PMID: 17406880 DOI: 10.1007/s00411-007-0098-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2006] [Accepted: 01/22/2007] [Indexed: 05/14/2023]
Abstract
The non-random distribution of DNA breakage in pulsed-field gel electrophoresis (PFGE) experiments poses a problem of proper subtraction of the background damage to obtain a fragment-size distribution due to radiation only. As been pointed out by various authors, a naive bin-to-bin subtraction of the background signal will not result in the right DNA mass distribution histogram, and may even result in negative values. Previous more systematic subtraction methods have been based mainly on random breakage, appropriate for low-LET radiation but problematic for high LET. Moreover, an investigation is needed whether the background breakage itself is random or non-random. Previously a new generalized formalism based on stochastic processes for the subtraction of the background damage in PFGE experiments for any LET and any background was proposed, and as now applied it to a set of PFGE data for Fe ions. We developed a Monte Carlo algorithm to compare the naïve subtraction procedure in artificial data sets to the result produced by the new formalism. The simulated data corresponded to various cases, involving non-random (high-LET) or random radiation breakage and random or non-random background breakage. The formalism systematically gives better results than naïve bin-by-bin subtraction in all these artificial data sets.
Collapse
Affiliation(s)
- Artem L Ponomarev
- NASA Johnson Space Center, Mail Code SK, build. 37, room 119, Houston, TX 77058, USA.
| | | | | | | | | | | |
Collapse
|
34
|
Claesson AK, Stenerlöw B, Jacobsson L, Elmroth K. Relative biological effectiveness of the alpha-particle emitter (211)At for double-strand break induction in human fibroblasts. Radiat Res 2007; 167:312-8. [PMID: 17316073 DOI: 10.1667/rr0668.1] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2006] [Accepted: 10/12/2006] [Indexed: 11/03/2022]
Abstract
The purpose of this study was to quantify and to determine the distribution of DNA double-strand breaks (DSBs) in human cells irradiated in vitro and to evaluate the relative biological effectiveness (RBE) of the alpha-particle emitter (211)At for DSB induction. The influence of the irradiation temperature on the induction of DSBs was also investigated. Human fibroblasts were irradiated as intact cells with alpha particles from (211)At, (60)Co gamma rays and X rays. The numbers and distributions of DSBs were determined by pulsed-field gel electrophoresis with fragment analysis for separation of DNA fragments in sizes 10 kbp-5.7 Mbp. A non-random distribution was found for DSB induction after irradiation with alpha particles from (211)At, while irradiation with low-LET radiation led to more random distributions. The RBEs for DSB induction were 2.1 and 3.1 for (60)Co gamma rays and X rays as the reference radiation, respectively. In the experiments studying temperature effects, nuclear monolayers were irradiated with (211)At alpha particles or (60)Co gamma rays at 2 degrees C or 37 degrees C and intact cells were irradiated with (211)At alpha particles at the same temperatures. The dose-modifying factor (DMF(temp)) for irradiation of nuclear monolayers at 37 degrees C compared with 2 degrees C was 1.7 for (211)At alpha particles and 1.6 for (60)Co gamma rays. No temperature effect was observed for intact cells irradiated with (211)At. In conclusion, irradiation with alpha particles from (211)At induced two to three times more DSB than gamma rays and X rays.
Collapse
Affiliation(s)
- Anna Kristina Claesson
- Department of Oncology, Institute of Clinical Sciences, Göteborg University, Sahlgrenska University Hospital, SE-413 45 Göteborg, Sweden.
| | | | | | | |
Collapse
|
35
|
Ponomarev AL, Belli M, Hahnfeldt PJ, Hlatky L, Sachs RK, Cucinotta FA. A Robust Procedure for Removing Background Damage in Assays of Radiation-Induced DNA Fragment Distributions. Radiat Res 2006; 166:908-16. [PMID: 17149980 DOI: 10.1667/rr0663.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2006] [Accepted: 07/26/2006] [Indexed: 11/03/2022]
Abstract
The non-random distribution of DNA breakage in PFGE (pulsed-field gel electrophoresis) experiments poses a problem of proper subtraction of the background DNA damage to obtain a fragment-size distribution due to radiation only. A naive bin-to-bin subtraction of the background signal will not result in the right DNA mass distribution histogram. This problem could become more pronounced for high-LET (linear energy transfer) radiation, because the fragment-size distribution manifests a higher frequency of smaller fragments. Previous systematic subtraction methods have been based on random breakage, appropriate for low-LET radiation. Moreover, an investigation is needed to determine whether the background breakage is itself random or non-random. We consider two limiting cases: (1) the background damage is present in all cells, and (2) it is present in only a small subset of cells, while other cells are not contributing to the background DNA fragmentation. We give a generalized formalism based on stochastic processes for the subtraction of the background damage in PFGE experiments for any LET and apply it to two sets of PFGE data for iron ions.
Collapse
|
36
|
Ponomarev AL, Cucinotta FA. Chromatin loops are responsible for higher counts of small DNA fragments induced by high-LET radiation, while chromosomal domains do not affect the fragment sizes. Int J Radiat Biol 2006; 82:293-305. [PMID: 16690597 DOI: 10.1080/09553000600637716] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
PURPOSE To apply a polymer model of DNA damage induced by high-LET (linear energy transfer) radiation and determine the influence of chromosomal domains and loops on fragment length distribution. MATERIALS AND METHODS The yields of DSB (double-strand breaks) induced by high-LET radiation were calculated using a track structure model along with a polymer model of DNA packed in the cell nucleus. The cell nucleus was constructed to include the chromosomal domains and chromatin loops. The latter were generated by the random walk method. RESULTS AND CONCLUSIONS We present data for DSB yields per track per cell, DNA fragment sizes, the radial distribution of DSB with respect to the track center, and the distribution of 0, 1, 2, and more DSB from a single particle. Calculations were carried out for a range of particles including He (40 keV/microm), N (225 keV/microm), and Fe ions (150 keV/mum). Situations relevant to PFGE (pulsed-field gel electrophoresis) and microbeam experiments with direct irradiation of the cell nucleus were simulated to demonstrate the applicability of the model. Data show that chromosomal domains do not have a significant influence on fragment-size distribution, while the presence of DNA loops increases the frequencies of smaller fragments by nearly 30% for fragment sizes in the range from 2 kbp (bp = base pair) to 20 kbp.
Collapse
|
37
|
Costes SV, Boissière A, Ravani S, Romano R, Parvin B, Barcellos-Hoff MH. Imaging features that discriminate between foci induced by high- and low-LET radiation in human fibroblasts. Radiat Res 2006; 165:505-15. [PMID: 16669704 DOI: 10.1667/rr3538.1] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
In this study, we investigated the formation of radiation-induced foci in normal human fibroblasts exposed to X rays or 130 keV/mum nitrogen ions using antibodies to phosphorylated protein kinase ataxia telangiectasia mutated (ATMp) and histone H2AX (gamma-H2AX). High-content automatic image analysis was used to quantify the immunofluorescence of radiation-induced foci. The size of radiation-induced foci increased for both proteins over a 2-h period after nitrogen-ion irradiation, while the size of radiation-induced foci did not change after exposure to low-LET radiation. The number of radiation-induced ATMp foci showed a more rapid rise and greater frequency after X-ray exposure and was resolved more rapidly such that the frequency of radiation-induced foci decreased by 90% compared to 60% after exposure to high-LET radiation 2 h after 30 cGy. In contrast, the kinetics of radiation-induced gamma-H2AX focus formation was similar for high- and low-LET radiation in that it reached a plateau early and remained constant for up to 2 h. High-resolution 3D images of radiation-induced gamma-H2AX foci and dosimetry computation suggest that multiple double-strand breaks from nitrogen ions are encompassed within large nuclear domains of 4.4 Mbp. Our work shows that the size and frequency of radiation-induced foci vary as a function of radiation quality, dose, time and protein target. Thus, even though double-strand breaks and radiation-induced foci are correlated, the dynamic nature of both contradicts their accepted equivalence for low doses of different radiation qualities.
Collapse
Affiliation(s)
- Sylvain V Costes
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
| | | | | | | | | | | |
Collapse
|
38
|
Anderson RM, Sumption ND, Papworth DG, Goodhead DT. Chromosome breakpoint distribution of damage induced in peripheral blood lymphocytes by densely ionizing radiation. Int J Radiat Biol 2006; 82:49-58. [PMID: 16546903 DOI: 10.1080/09553000600579231] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
PURPOSE To assess the chromosomal breakpoint distribution in human peripheral blood lymphocytes (PBL) after exposure to a low dose of high linear energy transfer (LET) alpha-particles using the technique of multiplex fluorescence in situ hybridization (m-FISH). MATERIALS AND METHODS Separated PBL were exposed in G0 to 0.5 Gy 238Pu alpha-particles, stimulated to divide and harvested approximately 48 - 50 hours after exposure. Metaphase cells were assayed by m-FISH and chromosome breaks identified. The observed distribution of breaks were then compared with expected distributions of breaks, calculated on the assumption that the distribution of breaks is random with regard to either chromosome volume or chromosome surface area. RESULTS More breaks than expected were observed on chromosomes 2 and 11, however no particular region of either chromosome was identified as significantly contributing to this over-representation. The identification of hot or cold chromosome regions (pter,p,cen,q,qter) varied depending on whether the data were compared according to chromosome volume or surface area. CONCLUSIONS A deviation from randomness in chromosome breakpoint distribution was observed, and this was greatest when data were compared according to the relative surface area of each individual chromosome (or region). The identification of breaks by m-FISH (i.e., more efficient observation of interchanges than intrachanges) and importance of territorial boundaries on interchange formation are thought to contribute to these differences. The significance of the observed non-random distribution of breaks on chromosomes 2 and 11 in relation to chromatin organization is unclear.
Collapse
Affiliation(s)
- R M Anderson
- MRC Radiation and Genome Stability Unit, Harwell, Didcot, Oxfordshire, UK.
| | | | | | | |
Collapse
|
39
|
Rössler U, Hornhardt S, Seidl C, Müller-Laue E, Walsh L, Panzer W, Schmid E, Senekowitsch-Schmidtke R, Gomolka M. The sensitivity of the alkaline comet assay in detecting DNA lesions induced by X rays, gamma rays and alpha particles. RADIATION PROTECTION DOSIMETRY 2006; 122:154-9. [PMID: 17182604 DOI: 10.1093/rpd/ncl424] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Experiments were designed and performed in order to investigate whether or not the different cellular energy deposition patterns of photon radiation with different energies (29 kV, 220 kV X rays; Co-60, Cs-137-gamma-rays) and alpha-radiation from an Am-241 source differ in DNA damage induction capacity in human cells. For this purpose, the alkaline comet assay (single cell gel electrophoresis) was applied to measure the amount of DNA damage in relation to the dose received. The comet assay data for the parameters '% DNA in the tail' and 'tail moment' for human peripheral lymphocytes did not indicate any difference in the initial radiation damage produced by 29 kV X rays relative to the reference radiations, 220 kV X rays and the gamma rays, whether for the total mean dose range of 0-3 Gy nor in the low-dose range. In contrast, when the 'tail length' data were analysed saturation of the fitted dose response curve appeared for X rays at about 1.5 Gy but was not apparent for gamma rays up to 3 Gy. Preliminary data for alpha exposures of HSC45-M2 cells showed a significant increase in DNA damage only at high doses (>2 Gy Am-241), but the damage at 2 Gy exceeded the damage induced at 2 Gy by Cs-137-gamma-rays by a factor of 2.5. In contrast, other experiments involving different cell systems and DNA damage indicators such as chromosomal aberrations have detected a significant increase in DNA damage at much lower doses, that is at 0.02 Gy for Am-241 and depicte a higher biological effectiveness. These results indicate that differences in biological effects arise through downstream processing of complex DNA damage.
Collapse
Affiliation(s)
- U Rössler
- Federal Office for Radiation Protection, Department Radiation Protection and Health, Ingolstädter Landstrasse 1, 85764 Oberschleissheim, Germany
| | | | | | | | | | | | | | | | | |
Collapse
|
40
|
Pinto M, Prise KM, Michael BD. Evidence for complexity at the nanometer scale of radiation-induced DNA DSBs as a determinant of rejoining kinetics. Radiat Res 2005; 164:73-85. [PMID: 15966767 DOI: 10.1667/rr3394] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The rejoining kinetics of double-stranded DNA fragments, along with measurements of residual damage after postirradiation incubation, are often used as indicators of the biological relevance of the damage induced by ionizing radiation of different qualities. Although it is widely accepted that high-LET radiation-induced double-strand breaks (DSBs) tend to rejoin with kinetics slower than low-LET radiation-induced DSBs, possibly due to the complexity of the DSB itself, the nature of a slowly rejoining DSB-containing DNA lesion remains unknown. Using an approach that combines pulsed-field gel electrophoresis (PFGE) of fragmented DNA from human skin fibroblasts and a recently developed Monte Carlo simulation of radiation-induced DNA breakage and rejoining kinetics, we have tested the role of DSB-containing DNA lesions in the 8-kbp-5.7-Mbp fragment size range in determining the DSB rejoining kinetics. It is found that with low-LET X rays or high-LET alpha particles, DSB rejoining kinetics data obtained with PFGE can be computer-simulated assuming that DSB rejoining kinetics does not depend on spacing of breaks along the chromosomes. After analysis of DNA fragmentation profiles, the rejoining kinetics of X-ray-induced DSBs could be fitted by two components: a fast component with a half-life of 0.9+/-0.5 h and a slow component with a half-life of 16+/-9 h. For alpha particles, a fast component with a half-life of 0.7+/-0.4 h and a slow component with a half-life of 12+/-5 h along with a residual fraction of unrepaired breaks accounting for 8% of the initial damage were observed. In summary, it is shown that genomic proximity of breaks along a chromosome does not determine the rejoining kinetics, so the slowly rejoining breaks induced with higher frequencies after exposure to high-LET radiation (0.37+/-0.12) relative to low-LET radiation (0.22+/-0.07) can be explained on the basis of lesion complexity at the nanometer scale, known as locally multiply damaged sites.
Collapse
Affiliation(s)
- M Pinto
- Gray Cancer Institute, Mount Vernon Hospital, Northwood, HA6 2JR Middlesex, United Kingdom.
| | | | | |
Collapse
|
41
|
Elmroth K, Stenerlöw B. DNA-Incorporated125I Induces more than one Double-Strand Break per Decay in Mammalian Cells. Radiat Res 2005; 163:369-73. [PMID: 15799691 DOI: 10.1667/rr3339] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The Auger-electron emitter 125I releases cascades of 20 electrons per decay that deposit a great amount of local energy, and for DNA-incorporated 125I, approximately one DNA double-strand break (DSB) is produced close to the decay site. To investigate the potential of 125I to induce additional DSBs within adjacent chromatin structures in mammalian cells, we applied DNA fragment-size analysis based on pulsed-field gel electrophoresis (PFGE) of hamster V79-379A cells exposed to DNA-incorporated 125IdU. After accumulation of decays at -70 degrees C in the presence of 10% DMSO, there was a non-random distribution of DNA fragments with an excess of fragments <0.5 Mbp and the measured yield was 1.6 DSBs/decay. However, since these experiments were performed under high scavenging conditions (DMSO) that reduce indirect effects, the yield in cells exposed to 125IdU under physiological conditions would most likely be even higher. In contrast, using a conventional low-resolution assay without measurement of smaller DNA fragments, the yield was close to one DSB/decay. We conclude that a large fraction of the DSBs induced by DNA-incorporated 125I are nonrandomly distributed and that significantly more than one DSB/decay is induced in an intact cell. Thus, in addition to DSBs produced close to the decay site, DSBs may also be induced within neighboring chromatin fibers, releasing smaller DNA fragments that are not detected by conventional DSB assays.
Collapse
Affiliation(s)
- Kecke Elmroth
- Division of Biomedical Radiation Sciences, Department of Oncology, Radiology and Clinical Immunology, Uppsala University, Rudbeck Laboratory, SE-751 85 Uppsala, Sweden
| | | |
Collapse
|
42
|
Camparoto ML, Takahashi-Hyodo SA, Dauwerse JG, Natarajan AT, Sakamoto-Hojo ET. High susceptibility of chromosome 16 to radiation-induced chromosome rearrangements in human lymphocytes under in vivo and in vitro exposure. Cytogenet Genome Res 2004; 108:287-92. [PMID: 15627747 DOI: 10.1159/000081522] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2004] [Accepted: 06/25/2004] [Indexed: 11/19/2022] Open
Abstract
The aim of the present study was to investigate whether chromosome 16p presents breakpoint regions susceptible to radiation-induced rearrangements. The frequencies of translocations were determined by fluorescence in situ hybridization (FISH) using cosmid probes C40 and C55 mapping on chromosome 16p, and a chromosome 16 centromere-specific probe (pHUR195). Peripheral lymphocytes were collected from normal individuals and from seven victims of 137Cs in the Goiania (Brasil) accident (absorbed doses: 0.8-4.6 Gy) 10 years after exposure. In vitro irradiated lymphocytes (3 Gy) were also analyzed. The mean translocation frequency/cell obtained for the 137Cs exposed individuals was 2.4-fold higher than the control value (3.6 x 10(-3) +/- 0.001), and the in vitro irradiated lymphocytes showed a seven-fold increase. The genomic translocation frequencies (FGs) were calculated by the formula Fp = 2.05 fp(1-fp)FG (Lucas et al., 1992). For the irradiated lymphocytes and victims of 137Cs, the FGs calculated on the basis of chromosome 16 were 2- to 8-fold higher than those for chromosomes 1, 4 and 12. Our results indicate that chromosome 16 is more prone to radiation-induced chromosome breaks, and demonstrate a non-random distribution of induced aberrations. This information is valuable for retrospective biological dosimetry in case of human exposure to radiation, since the estimates of absorbed doses are calculated by determining the translocation frequency for a sub-set of chromosomes, and the results are extrapolated to the whole genome, assuming a random distribution of induced aberrations. Furthermore, the demonstration of breakpoints on 16p is compatible with the reports about their involvement in neoplasias.
Collapse
Affiliation(s)
- M L Camparoto
- Departamento de Genética, Faculdade de Medicina de Ribeirão Preto, Ribeirão Preto, SP, Brasil
| | | | | | | | | |
Collapse
|
43
|
Mitchell CR, Azizova TV, Hande MP, Burak LE, Tsakok JM, Khokhryakov VF, Geard CR, Brenner DJ. Stable Intrachromosomal Biomarkers of Past Exposure to Densely Ionizing Radiation in Several Chromosomes of Exposed Individuals. Radiat Res 2004; 162:257-63. [PMID: 15378838 DOI: 10.1667/rr3231] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
A multicolor banding (mBAND) fluorescence in situ hybridization technique was used to investigate the presence inhuman populations of a stable biomarker-intrachromosomal chromosome aberrations-of past exposure to high-LET radiation. Peripheral blood lymphocytes were taken from healthy Russian nuclear workers occupationally exposed from 1949 onward to either plutonium, gamma rays or both. Metaphase spreads were produced and chromosomes 1 and 2 were hybridized with mBAND FISH probes and scored for intra-chromosomal aberrations. A large yield of intrachromosomal aberrations was observed in both chromosomes of the individuals exposed to high doses of plutonium, whereas there was no significant increase over the (low) background control rate in the population who were exposed to high doses of gamma rays. Interchromosome aberration yields were similar in both the high plutonium and the high gamma-ray groups. These results for chromosome 1 and 2 confirm and extend data published previously for chromosome 5. Intrachromosomal aberrations thus represent a potential biomarker for past exposure to high-LET radiations such as alpha particles and neutrons and could possibly be used as a biodosimeter to estimate both the dose and type of radiation exposure in previously exposed populations.
Collapse
Affiliation(s)
- Catherine R Mitchell
- Center for Radiological Research, Columbia University, New York, New York 10032, USA.
| | | | | | | | | | | | | | | |
Collapse
|
44
|
Karlsson KH, Stenerlöw B. Focus formation of DNA repair proteins in normal and repair-deficient cells irradiated with high-LET ions. Radiat Res 2004; 161:517-27. [PMID: 15161372 DOI: 10.1667/rr3171] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
To investigate the repair of clustered lesions within the DNA/chromatin, the focus formation and persistence of foci of the phosphorylated histone protein H2AX and the repair protein MRE11 were studied in normal cells and in cells lacking DNA-PKcs (M059J) or ATM (GM2052D) after irradiation with high-LET nitrogen ions or low-LET photons. There was a rapid formation of MRE11 and gamma-H2AX foci, and 0.5 h after high-LET irradiation, the number of foci in normal cells correlated well with the number of particle hits per cell nucleus. After 8 h of repair, there were significantly more gamma-H2AX foci than MRE11 foci remaining in the normal cells, independent of radiation quality. The difficulty in repairing clustered breaks was detected as slower rejoining of DSBs (measured by DNA fragmentation analysis), as quantification of the amount of gamma-H2AX over time, and as a larger fraction of repair foci remaining after 24 h in cells irradiated with high- LET ions. These data indicate that clustered lesions are repaired by a pathway involving the same proteins that repair sparsely distributed breaks. Further, for both low- and high- LET radiation, no reduction of the initial number of gamma-H2AX and MRE11 foci was detected in M059J cells up to 21 h after irradiation, which was in accordance with a complete absence of DSB rejoining in these cells. In the GM2052D cells there was also a higher level of foci remaining after 21 h; however, this was not accompanied by unrejoined DSBs, indicating that these foci not only represent DSBs but also may be a sign of persistent problems even when breaks are rejoined.
Collapse
Affiliation(s)
- Karin H Karlsson
- Division of Biomedical Radiation Sciences, Rudbeck Laboratory, Uppsala University, SE-75185 Uppsala, Sweden.
| | | |
Collapse
|
45
|
Abstract
The relative biological-effectiveness of radiation is increased when cells or tissue are exposed to densely ionizing (high-LET) radiation. A large number of studies focus on the following aspects of the biological effects of high-LET radiation: (i) basic understanding of radiation damage and repair; (ii) developing radiotherapy protocols for accelerated charged particles; and (iii) estimation of human risks from exposure to high-LET heavy charged particles. The increased lethal effectiveness (cell inactivation) of high-LET radiation contributes to new methods for using radiation therapy, but it is also necessary to study the enhanced mutagenic effect of high LET radiation, because higher frequencies of mutation can be expected to provide higher rates of carcinogenicity with human exposure. It is important to note that both measures of biological effectiveness (lethality and mutagenicity) depend on the quality of radiation, the dose, dose-rate effects, and the biological endpoints studied. This paper is intended to provide a review of current research on the mutagenic effects of high-LET radiation, and is organized into three sections. First, are descriptions of the induced mutations studied with various detection systems (section 1) because the detectable mutations induced by ionizing radiation, including heavy-ions, depend largely on the detection system used. Second is a discussion of the biological significance of the dependence of induced mutations on LET (section 2). This is related to the molecular nature of radiation lesions and to the repair mechanisms used to help cells recover from such damage. Finally, applications of mutation detection systems for studies in space (section 3) are described, in which the carcinogenic effects of space environmental radiation are considered.
Collapse
Affiliation(s)
- Fumio Yatagai
- Advanced Development and Support Center, RIKEN Institute, Wako-shi, Saitama, Japan.
| |
Collapse
|