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Abstract
A classical dogma of radiation biology asserts that all effects of radiation on cells are due to it's direct, immediate actions. But evidence accumulated over the last 50 years shows that radiation also has, indirect ‘non-target’ actions including ‘bystander’ effects in which effects of radiation on cells or media are transported to cells or tissues that were not ‘hit’ by the radiation, leading to changes in their function. This important but heretical recognition of radiation actions has been referred to, probably incorrectly, as a ‘paradigm shift.’ What these signals are and how they induce changes is not well understood. Also not clear is how, or if, bystander effects might affect risk estimates for exposure to low doses of radiation. These issues are reviewed and explored in this series of papers.
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Affiliation(s)
- Charles A Waldren
- Radiation Effects Research Foundations, Hijiyama Park, Minami-ku, Hiroshima, Japan.
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2
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Madas BG. Radon Exposure and the Definition of Low Doses-The Problem of Spatial Dose Distribution. HEALTH PHYSICS 2016; 111:47-51. [PMID: 27218294 DOI: 10.1097/hp.0000000000000516] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Investigating the health effects of low doses of ionizing radiation is considered to be one of the most important fields in radiological protection research. Although the definition of low dose given by a dose range seems to be clear, it leaves some open questions. For example, the time frame and the target volume in which absorbed dose is measured have to be defined. While dose rate is considered in the current system of radiological protection, the same cancer risk is associated with all exposures, resulting in a given amount of energy absorbed by a single target cell or distributed among all the target cells of a given organ. However, the biological effects and so the health consequences of these extreme exposure scenarios are unlikely to be the same. Due to the heterogeneous deposition of radon progeny within the lungs, heterogeneous radiation exposure becomes a practical issue in radiological protection. While the macroscopic dose is still within the low dose range, local tissue doses on the order of Grays can be reached in the most exposed parts of the bronchial airways. It can be concluded that progress in low dose research needs not only low dose but also high dose experiments where small parts of a biological sample receive doses on the order of Grays, while the average dose over the whole sample remains low. A narrow interpretation of low dose research might exclude investigations with high relevance to radiological protection. Therefore, studies important to radiological protection should be performed in the frame of low dose research even if the applied doses do not fit in the dose range used for the definition of low doses.
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Affiliation(s)
- Balázs G Madas
- *Environmental Physics Department, Centre for Energy Research, Hungarian Academy of Sciences
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3
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Alexandrou AT, Li JJ. Cell cycle regulators guide mitochondrial activity in radiation-induced adaptive response. Antioxid Redox Signal 2014; 20:1463-80. [PMID: 24180340 PMCID: PMC3936506 DOI: 10.1089/ars.2013.5684] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
SIGNIFICANCE There are accruing concerns on potential genotoxic agents present in the environment including low-dose ionizing radiation (LDIR) that naturally exists on earth's surface and atmosphere and is frequently used in medical diagnosis and nuclear industry. Although its long-term health risk is being evaluated and remains controversial, LDIR is shown to induce temporary but significant adaptive responses in mammalian cells and animals. The mechanisms guiding the mitochondrial function in LDIR-induced adaptive response represent a unique communication between DNA damage and cellular metabolism. Elucidation of the LDIR-regulated mitochondrial activity may reveal new mechanisms adjusting cellular function to cope with hazardous environmental stress. RECENT ADVANCES Key cell cycle regulators, including Cyclin D1/CDK4 and Cyclin B1/cyclin-dependent kinase 1 (CDK1) complexes, are actively involved in the regulation of mitochondrial functions via phosphorylation of their mitochondrial targets. Accumulating new evidence supports a concept that the Cyclin B1/CDK1 complex acts as a mediator in the cross talk between radiation-induced DNA damage and mitochondrial functions to coordinate cellular responses to low-level genotoxic stresses. CRITICAL ISSUES The LDIR-mediated mitochondrial activity via Cyclin B1/CDK1 regulation is an irreplaceable network that is able to harmonize vital cellular functions with adjusted mitochondrial metabolism to enhance cellular homeostasis. FUTURE DIRECTIONS Further investigation of the coordinative mechanism that regulates mitochondrial activities in sublethal stress conditions, including LDIR, will reveal new insights of how cells cope with genotoxic injury and will be vital for future targeted therapeutic interventions that reduce environmental injury and cancer risk.
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Affiliation(s)
- Aris T Alexandrou
- Department of Radiation Oncology, NCI-Designated Comprehensive Cancer Center, University of California at Davis , Sacramento, California
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4
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Yang F, Waters KM, Webb-Robertson BJ, Sowa MB, von Neubeck C, Aldrich JT, Markillie LM, Wirgau RM, Gritsenko MA, Zhao R, Camp DG, Smith RD, Stenoien DL. Quantitative phosphoproteomics identifies filaggrin and other targets of ionizing radiation in a human skin model. Exp Dermatol 2012; 21:352-7. [PMID: 22509832 DOI: 10.1111/j.1600-0625.2012.01470.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Our objective here was to perform a quantitative phosphoproteomic study on a reconstituted human skin tissue to identify low- and high-dose ionizing radiation-dependent signalling in a complex three-dimensional setting. Application of an isobaric labelling strategy using sham and three radiation doses (3, 10, 200 cGy) resulted in the identification of 1052 unique phosphopeptides. Statistical analyses identified 176 phosphopeptides showing significant changes in response to radiation and radiation dose. Proteins responsible for maintaining skin structural integrity including keratins and desmosomal proteins (desmoglein, desmoplakin, plakophilin 1, 2 and 3) had altered phosphorylation levels following exposure to both low and high doses of radiation. Altered phosphorylation of multiple sites in profilaggrin linker domains coincided with altered profilaggrin processing suggesting a role for linker phosphorylation in human profilaggrin regulation. These studies demonstrate that the reconstituted human skin system undergoes a coordinated response to both low and high doses of ionizing radiation involving multiple layers of the stratified epithelium that serve to maintain tissue integrity and mitigate effects of radiation exposure.
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Affiliation(s)
- Feng Yang
- Pacific Northwest National Laboratory, Richland, WA 99352, USA
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Pelevina II, Afanas’ev GG, Aleshchenko AV, Antoshchina MM, Gotlib VY, Konradov AA, Kudryashova OV, Lizunova EY, Osipov AN, Ryabchenko NI, Serebryanyi AM. The molecular and cellular consequences of the chernobyl accident. Biophysics (Nagoya-shi) 2011. [DOI: 10.1134/s0006350911030237] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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7
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Birschwilks M, Gruenberger M, Adelmann C, Tapio S, Gerber G, Schofield PN, Grosche B. The European Radiobiological Archives: Online Access to Data from Radiobiological Experiments. Radiat Res 2011; 175:526-31. [DOI: 10.1667/rr2471.1] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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8
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Ivanova TI, Kondrashova TV, Krikunova LI, Smirnova IA, Shentereva NI, Sychenkova NI, Rykova EV, Zharikova IA, Khorokhorina VA, Ryabchenko NI, Zamulaeva IA. Polymorphism of genes for catechol-O-methyltransferase (COMT) and hemochromatosis (HFE) in residents of radiocontaminated regions varying in chromosome aberration frequency. Biophysics (Nagoya-shi) 2011. [DOI: 10.1134/s0006350910060333] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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9
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Blankenbecler R. Radiation worker protection by exposure scheduling. Dose Response 2011; 9:465-70. [PMID: 22461756 DOI: 10.2203/dose-response.11-029.blankenbecler] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
The discovery of the protective adaptive response of cells to a low dose of radiation suggests applications to radiation worker/first responder protection. Its use in cancer radiotherapy has been discussed in a separate publication. This paper describes simple changes in scheduling that can make use of these beneficial adaptive effects for protection. No increase in total exposure is necessary, only a simple change in the timing of radiation exposure. A low dose of radiation at a sufficient dose rate will trigger the adaptive response. This in turn will offer a considerable protection against the damage from a subsequent high dose. A simple scenario is discussed as well as a brief review of the experimental basis of the adaptive response.
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Phosphoproteomics profiling of human skin fibroblast cells reveals pathways and proteins affected by low doses of ionizing radiation. PLoS One 2010; 5:e14152. [PMID: 21152398 PMCID: PMC2994767 DOI: 10.1371/journal.pone.0014152] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2010] [Accepted: 10/25/2010] [Indexed: 12/26/2022] Open
Abstract
Background High doses of ionizing radiation result in biological damage; however, the precise relationships between long-term health effects, including cancer, and low-dose exposures remain poorly understood and are currently extrapolated using high-dose exposure data. Identifying the signaling pathways and individual proteins affected at the post-translational level by radiation should shed valuable insight into the molecular mechanisms that regulate dose-dependent responses to radiation. Principal Findings We have identified 7117 unique phosphopeptides (2566 phosphoproteins) from control and irradiated (2 and 50 cGy) primary human skin fibroblasts 1 h post-exposure. Semi-quantitative label-free analyses were performed to identify phosphopeptides that are apparently altered by radiation exposure. This screen identified phosphorylation sites on proteins with known roles in radiation responses including TP53BP1 as well as previously unidentified radiation-responsive proteins such as the candidate tumor suppressor SASH1. Bioinformatic analyses suggest that low and high doses of radiation affect both overlapping and unique biological processes and suggest a role for MAP kinase and protein kinase A (PKA) signaling in the radiation response as well as differential regulation of p53 networks at low and high doses of radiation. Conclusions Our results represent the most comprehensive analysis of the phosphoproteomes of human primary fibroblasts exposed to multiple doses of ionizing radiation published to date and provide a basis for the systems-level identification of biological processes, molecular pathways and individual proteins regulated in a dose dependent manner by ionizing radiation. Further study of these modified proteins and affected networks should help to define the molecular mechanisms that regulate biological responses to radiation at different radiation doses and elucidate the impact of low-dose radiation exposure on human health.
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Locke PA. Incorporating information from the U.S. Department of Energy low-dose program into regulatory decision-making: three policy integration challenges. HEALTH PHYSICS 2009; 97:510-515. [PMID: 19820461 DOI: 10.1097/hp.0b013e3181b18737] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The U.S. Department of Energy (U.S. DOE) sponsors a research program aimed at gaining a better understanding of how low-dose radiation affects cellular functioning and progression toward disease. There have been calls to incorporate into regulatory decision-making the scientific information that this program has produced. After a discussion of the evolution of radiation protection law and the weight-of-evidence approach that agencies employ, this paper offers some preliminary thoughts about how to approach this complex and important policy question. Three implementation challenges are identified and discussed. The first implementation challenge involves explaining low-dose effects in a systems biology model. The second challenge arises when issues of population susceptibility are juxtaposed against molecular and mechanistic studies, such as those that make up much of the U.S. DOE low-dose program. The third challenge concerns integrating the results of radiation epidemiology, especially epidemiologic studies among cohorts that are exposed to low dose and low-dose rate radiation, with the results of U.S. DOE low-dose studies.
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Affiliation(s)
- Paul A Locke
- Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Room W7032G, Baltimore, MD 21205, USA.
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Tapio S, Schofield PN, Adelmann C, Atkinson MJ, Bard JLB, Bijwaard H, Birschwilks M, Dubus P, Fiette L, Gerber G, Gruenberger M, Quintanilla-Martinez L, Rozell B, Saigusa S, Warren M, Watson CR, Grosche B. Progress in updating the European Radiobiology Archives. Int J Radiat Biol 2009; 84:930-6. [PMID: 19016141 DOI: 10.1080/09553000802460214] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
PURPOSE The European Radiobiology Archives (ERA), together with corresponding Japanese and American databases, hold data from nearly all experimental animal radiation biology studies carried out between 1960 and 1998, involving more than 300,000 animals. The Federal Office for Radiation Protection, together with the University of Cambridge have undertaken to transfer the existing ERA archive to a web-based database to maximize its usefulness to the scientific community and bring data coding and structure of this legacy database into congruence with currently accepted semantic standards for anatomy and pathology. METHODS The accuracy of the primary data input was assessed and improved. The original rodent pathology nomenclature was recoded to replace the local 'DIS-ROD' (Disease Rodent) formalism with Mouse Pathology (MPATH) and Mouse Anatomy (MA) ontology terms. A pathology panel sampled histopathological slide material and compared the original diagnoses with currently accepted diagnostic criteria. RESULTS The overall non-systematic error rate varied among the studies between 0.26% and 4.41%, the mean error being 1.71%. The errors found have been corrected and the studies thus controlled have been annotated. The majority of the original pathology terms have been successfully translated into a combination of MPATH and MA ontology terms. CONCLUSIONS ERA has the potential of becoming a world-wide radiobiological research tool for numerous applications, such as the re-analysis of existing data with new approaches in the light of new hypotheses and techniques, and using the database as an information resource for planning future animal studies. When the database is opened for new data it may be possible to offer long-term storage of data from recent and future animal studies.
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Affiliation(s)
- S Tapio
- Federal Office for Radiation Protection, Department of Radiation Protection and Health, Neuherberg, Germany.
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Delistraty D. Radioprotection of nonhuman biota. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2008; 99:1863-1869. [PMID: 18952327 DOI: 10.1016/j.jenvrad.2008.09.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2008] [Accepted: 09/08/2008] [Indexed: 05/27/2023]
Abstract
Radioprotection has historically focused on humans with the assumption that human protection confers protection of nonhuman biota. However, there is a need to scientifically and independently demonstrate protection of nonhuman biota. Approaches to address impacts of radiation on nonhuman biota include applying an ecological risk assessment paradigm, setting dose limits, defining reference organisms, and assessing a geographic region. Recommendations include harmonization of a radioprotection framework for both humans and nonhuman biota, a consistent methodology to evaluate radionuclide and nonradionuclide contaminants, a graded assessment approach, development of dosimetric models for reference organisms, compilation of a radiological effects database, and periodic expert review of methodology.
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Bladen CL, Navarre S, Dynan WS, Kozlowski DJ. Expression of the Ku70 subunit (XRCC6) and protection from low dose ionizing radiation during zebrafish embryogenesis. Neurosci Lett 2007; 422:97-102. [PMID: 17630212 PMCID: PMC2075087 DOI: 10.1016/j.neulet.2007.05.045] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2007] [Revised: 04/20/2007] [Accepted: 05/11/2007] [Indexed: 10/23/2022]
Abstract
The Ku70 protein, a product of the XRCC6 gene, is a component of the nonhomologous end-joining (NHEJ) pathway of DNA repair, which protects cells from the effects of radiation-induced DNA damage. Although the spatial expression of Ku70 during vertebrate embryogenesis has not been described, DNA repair proteins are generally considered to be "housekeeping" genes, which are required for radioprotection in all cells. Here, we report the cloning and characterization of the zebrafish Ku70 ortholog. In situ hybridization and RT-PCR analyses demonstrate that Ku70 mRNA is maternally provided and expressed uniformly among embryonic blastomeres. Later during embryogenesis, zygotically transcribed Ku70 mRNA specifically accumulates in neural tissue, including the retina and proliferative regions of the developing brain. In the absence of genotoxic stress, morpholino-mediated knockdown of Ku70 expression does not affect zebrafish embryogenesis. However, exposure of Ku70 morpholino-injected embryos to low doses of ionizing radiation leads to marked cell death throughout the developing brain, spinal cord, and tail. These results suggest that Ku70 protein plays a crucial role in protecting the developing nervous system from radiation-induced DNA damage during embryogenesis.
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MESH Headings
- Animals
- Antigens, Nuclear/genetics
- Antigens, Nuclear/isolation & purification
- Antigens, Nuclear/metabolism
- Cell Death/genetics
- Cell Death/radiation effects
- Cell Differentiation/genetics
- Cell Differentiation/radiation effects
- Cytoprotection/genetics
- Cytoprotection/radiation effects
- DNA Damage/genetics
- DNA Damage/radiation effects
- DNA Repair/genetics
- DNA Repair/radiation effects
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/isolation & purification
- DNA-Binding Proteins/metabolism
- Embryo, Nonmammalian/embryology
- Embryo, Nonmammalian/metabolism
- Embryo, Nonmammalian/radiation effects
- Embryonic Development/genetics
- Embryonic Development/radiation effects
- Gene Expression Regulation, Developmental/genetics
- Gene Expression Regulation, Developmental/radiation effects
- Ku Autoantigen
- Molecular Sequence Data
- RNA, Messenger/antagonists & inhibitors
- RNA, Messenger/metabolism
- Radiation Dosage
- Radiation, Ionizing
- Sequence Homology, Amino Acid
- Sequence Homology, Nucleic Acid
- Species Specificity
- Zebrafish/embryology
- Zebrafish/genetics
- Zebrafish/metabolism
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Affiliation(s)
- Catherine L. Bladen
- Institute of Molecular Medicine and Genetics, Medical College of Georgia, Augusta, GA, 30912, USA
| | - Sammy Navarre
- Institute of Molecular Medicine and Genetics, Medical College of Georgia, Augusta, GA, 30912, USA
| | - William S. Dynan
- Institute of Molecular Medicine and Genetics, Medical College of Georgia, Augusta, GA, 30912, USA
| | - David J. Kozlowski
- Institute of Molecular Medicine and Genetics, Medical College of Georgia, Augusta, GA, 30912, USA
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta, GA, 30912, USA
- Corresponding author: IMMAG, CB-2803, Medical College of Georgia,1120 15th Street, Augusta, GA 30912. Phone: (706) 721-8760. Fax: (706) 721-8752. E-mail:
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Albanese J, Martens K, Karanitsa LV, Karkanitsa LV, Schreyer SK, Dainiak N. Multivariate analysis of low-dose radiation-associated changes in cytokine gene expression profiles using microarray technology. Exp Hematol 2007; 35:47-54. [PMID: 17379087 DOI: 10.1016/j.exphem.2007.01.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
OBJECTIVE The availability of microarray technology, which permits evaluation of the entire cellular transcriptome in a single experiment, has provided new insights on the function of the genome under normal and pathological conditions, as well as in response to genotoxic stimuli, including ionizing radiation. The aims of this study were to: 1) determine whether specific cytokine gene expression profiles can be delineated in individuals exposed to chronic, low-dose radiation; and 2) compare analyses from three multivariate analytic methodologies, hierarchical clustering analysis (HCA), principal component analysis (PCA), and projection pursuit (PP), in evaluating transcriptional responses in human mononuclear cells to low doses of ionizing radiation (IR), as determined by cDNA microarrays. MATERIALS AND METHODS Total RNA isolated from mononuclear cells of 19 apparently healthy adult individuals exposed to low doses of IR ranging from 0.18 mSv to 49 mSv over a period of 11 to 13 years, as a result of the Chernobyl Nuclear Power Plant catastrophe, was reverse transcribed in the presence of radioactive dATP to generate radiolabeled complementary cDNA. Target cDNA was hybridized to human cytokine and receptor arrays and mRNA transcriptional patterns were evaluated using HCA, PCA, and PP. RESULTS Statistical analyses of the data generated from 19 microarrays revealed distinct gene expression patterns in mononuclear cells of individuals exposed to radiation doses of greater than 10 mSv or less than 10 mSv. Genes encompassed within clusters discerned by HCA, PCA, and PP varied depending on the methodology used to analyze the microarray data. The most frequently expressed genes across all radiation doses were serine/threonine protein kinase receptor (11/19), transforming growth factor (TGF) receptor (11/19), EB13 (10/19), and CD40 ligand. CONCLUSIONS Although our findings suggest that it may be possible to assign gene expression profiles to low-dose-irradiated individuals, we show that gene expression profiles vary, depending on the statistical method used to analyze the data. Since there is, as of yet, no consensus regarding the best method to analyze a multivariate dataset, and since discarding the raw data and repeating the experiment at a later date constitutes an unwarranted expenditure, it is important to submit microarray data to public databases where these data can be reevaluated and interpreted by investigators holding expertise in various fields within the scientific community, including radiation biology, statistics, and bioinformatics.
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Affiliation(s)
- Joseph Albanese
- Yale New Haven Health, Center for Emergency Preparedness and Disaster Response, New Haven, CT 06510, USA.
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Goldberg Z, Rocke DM, Schwietert C, Berglund SR, Santana A, Jones A, Lehmann J, Stern R, Lu R, Hartmann Siantar C. Human in vivo dose-response to controlled, low-dose low linear energy transfer ionizing radiation exposure. Clin Cancer Res 2006; 12:3723-9. [PMID: 16778099 DOI: 10.1158/1078-0432.ccr-05-2625] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE The effect of low doses of low-linear energy transfer (photon) ionizing radiation (LDIR, <10 cGy) on human tissue when exposure is under normal physiologic conditions is of significant interest to the medical and scientific community in therapeutic and other contexts. Although, to date, there has been no direct assessment of the response of human tissue to LDIR when exposure is under normal physiologic conditions of intact three-dimensional architecture, vasculature, and cell-cell contacts (between epithelial cells and between epithelial and stromal cells). EXPERIMENTAL DESIGN In this article, we present the first data on the response of human tissue exposed in vivo to LDIR with precisely controlled and calibrated doses. We evaluated transcriptomic responses to a single exposure of LDIR in the normal skin of men undergoing therapeutic radiation for prostate cancer (research protocol, Health Insurance Portability and Accountability Act-compliant, Institutional Review Board-approved). Using newly developed biostatistical tools that account for individual splice variants and the expected variability of temporal response between humans even when the outcome is measured at a single time, we show a dose-response pattern in gene expression in a number of pathways and gene groups that are biologically plausible responses to LDIR. RESULTS Examining genes and pathways identified as radiation-responsive in cell culture models, we found seven gene groups and five pathways that were altered in men in this experiment. These included the Akt/phosphoinositide-3-kinase pathway, the growth factor pathway, the stress/apoptosis pathway, and the pathway initiated by transforming growth factor-beta signaling, whereas gene groups with altered expression included the keratins, the zinc finger proteins and signaling molecules in the mitogen-activated protein kinase gene group. We show that there is considerable individual variability in radiation response that makes the detection of effects difficult, but still feasible when analyzed according to gene group and pathway. CONCLUSIONS These results show for the first time that low doses of radiation have an identifiable biosignature in human tissue, irradiated in vivo with normal intact three-dimensional architecture, vascular supply, and innervation. The genes and pathways show that the tissue (a) does detect the injury, (b) initiates a stress/inflammatory response, (c) undergoes DNA remodeling, as suggested by the significant increase in zinc finger protein gene expression, and (d) initiates a "pro-survival" response. The ability to detect a distinct radiation response pattern following LDIR exposure has important implications for risk assessment in both therapeutic and national defense contexts.
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Affiliation(s)
- Zelanna Goldberg
- Department of Radiation Oncology, University of California Davis Cancer Center, Sacramento, 95817, USA.
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Yang F, Stenoien DL, Strittmatter EF, Wang J, Ding L, Lipton MS, Monroe ME, Nicora CD, Gristenko MA, Tang K, Fang R, Adkins JN, Camp DG, Chen DJ, Smith RD. Phosphoproteome profiling of human skin fibroblast cells in response to low- and high-dose irradiation. J Proteome Res 2006; 5:1252-60. [PMID: 16674116 DOI: 10.1021/pr060028v] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A hallmark of the response to high-dose radiation is the up-regulation and phosphorylation of proteins involved in cell cycle checkpoint control, DNA damage signaling, DNA repair, and apoptosis. Exposure of cells to low doses of radiation has well documented biological effects, but the underlying regulatory mechanisms are still poorly understood. The objective of this study is to provide an initial profile of the normal human skin fibroblast (HSF) phosphoproteome and explore potential differences between low- and high-dose irradiation responses at the protein phosphorylation level. Several techniques including Trizol extraction of proteins, methylation of tryptic peptides, enrichment of phosphopeptides with immobilized metal affinity chromatography (IMAC), nanoflow reversed-phase HPLC (nano-LC)/electrospray ionization, and tandem mass spectrometry were combined for analysis of the HSF cell phosphoproteome. Among 494 unique phosphopeptides, 232 were singly phosphorylated, while 262 peptides had multiple phosphorylation sites indicating the overall effectiveness of the IMAC technique to enrich both singly and multiply phosphorylated peptides. We observed approximately 1.9-fold and approximately 3.6-fold increases in the number of identified phosphopeptides in low-dose and high-dose samples respectively, suggesting both radiation levels stimulate cell signaling pathways. A 6-fold increase in the phosphorylation of cyclin dependent kinase (cdk) motifs was observed after low- dose irradiation, while high-dose irradiation stimulated phosphorylation of 3-phosphoinositide-dependent protein kinase-1 (PDK1) and AKT/RSK motifs 8.5- and 5.5-fold, respectively. High- dose radiation resulted in the increased phosphorylation of proteins involved in cell signaling pathways as well as apoptosis while low-dose and control phosphoproteins were broadly distributed among biological processes.
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Affiliation(s)
- Feng Yang
- Biological Sciences Division and Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, USA
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Chaudhry MA. Bystander effect: biological endpoints and microarray analysis. Mutat Res 2006; 597:98-112. [PMID: 16414093 DOI: 10.1016/j.mrfmmm.2005.04.023] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2005] [Revised: 04/13/2005] [Accepted: 04/22/2005] [Indexed: 05/06/2023]
Abstract
In cell populations exposed to ionizing radiation, the biological effects occur in a much larger proportion of cells than are estimated to be traversed by radiation. It has been suggested that irradiated cells are capable of providing signals to the neighboring unirradiated cells resulting in damage to these cells. This phenomenon is termed the bystander effect. The bystander effect induces persistent, long-term, transmissible changes that result in delayed death and neoplastic transformation. Because the bystander effect is relevant to carcinogenesis, it could have significant implications for risk estimation for radiation exposure. The nature of the bystander effect signal and how it impacts the unirradiated cells remains to be elucidated. Examination of the changes in gene expression could provide clues to understanding the bystander effect and could define the signaling pathways involved in sustaining damage to these cells. The microarray technology serves as a tool to gain insight into the molecular pathways leading to bystander effect. Using medium from irradiated normal human diploid lung fibroblasts as a model system we examined gene expression alterations in bystander cells. The microarray data revealed that the radiation-induced gene expression profile in irradiated cells is different from unirradiated bystander cells suggesting that the pathways leading to biological effects in the bystander cells are different from the directly irradiated cells. The genes known to be responsive to ionizing radiation were observed in irradiated cells. Several genes were upregulated in cells receiving media from irradiated cells. Surprisingly no genes were found to be downregulated in these cells. A number of genes belonging to extracellular signaling, growth factors and several receptors were identified in bystander cells. Interestingly 15 genes involved in the cell communication processes were found to be upregulated. The induction of receptors and the cell communication processes in bystander cells receiving media from irradiated cells supports the active involvement of these processes in inducing bystander effect.
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Affiliation(s)
- M Ahmad Chaudhry
- Department of Medical Laboratory and Radiation Sciences, College of Nursing and Health Sciences, University of Vermont, 302 Rowell Building, Burlington, VT 05405, USA.
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Ding LH, Shingyoji M, Chen F, Hwang JJ, Burma S, Lee C, Cheng JF, Chen DJ. Gene expression profiles of normal human fibroblasts after exposure to ionizing radiation: a comparative study of low and high doses. Radiat Res 2005; 164:17-26. [PMID: 15966761 DOI: 10.1667/rr3354] [Citation(s) in RCA: 160] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Several types of cellular responses to ionizing radiation, such as the adaptive response or the bystander effect, suggest that low-dose radiation may possess characteristics that distinguish it from its high-dose counterpart. Accumulated evidence also implies that the biological effects of low-dose and high-dose ionizing radiation are not linearly distributed. We have investigated, for the first time, global gene expression changes induced by ionizing radiation at doses as low as 2 cGy and have compared this to expression changes at 4 Gy. We applied cDNA microarray analyses to G1-arrested normal human skin fibroblasts subjected to X irradiation. Our data suggest that both qualitative and quantitative differences exist between gene expression profiles induced by 2 cGy and 4 Gy. The predominant functional groups responding to low-dose radiation are those involved in cell-cell signaling, signal transduction, development and DNA damage responses. At high dose, the responding genes are involved in apoptosis and cell proliferation. Interestingly, several genes, such as cytoskeleton components ANLN and KRT15 and cell-cell signaling genes GRAP2 and GPR51, were found to respond to low-dose radiation but not to high-dose radiation. Pathways that are specifically activated by low-dose radiation were also evident. These quantitative and qualitative differences in gene expression changes may help explain the non-linear correlation of biological effects of ionizing radiation from low dose to high dose.
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Affiliation(s)
- Liang-Hao Ding
- Lawrence Berkeley National Laboratory, Life Sciences Division, Berkeley, California, 94720, USA
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Bladen CL, Lam WK, Dynan WS, Kozlowski DJ. DNA damage response and Ku80 function in the vertebrate embryo. Nucleic Acids Res 2005; 33:3002-10. [PMID: 15914672 PMCID: PMC1140083 DOI: 10.1093/nar/gki613] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Cellular responses to DNA damage reflect the dynamic integration of cell cycle control, cell–cell interactions and tissue-specific patterns of gene regulation that occurs in vivo but is not recapitulated in cell culture models. Here we describe use of the zebrafish embryo as a model system to identify determinants of the in vivo response to ionizing radiation-induced DNA damage. To demonstrate the utility of the model we cloned and characterized the embryonic function of the XRCC5 gene, which encodes Ku80, an essential component of the nonhomologous end joining pathway of DNA repair. After the onset of zygotic transcription, Ku80 mRNA accumulates in a tissue-specific pattern, which includes proliferative zones of the retina and central nervous system. In the absence of genotoxic stress, zebrafish embryos with reduced Ku80 function develop normally. However, low dose irradiation of these embryos during gastrulation leads to marked apoptosis throughout the developing central nervous system. Apoptosis is p53 dependent, indicating that it is a downstream consequence of unrepaired DNA damage. Results suggest that nonhomologous end joining components mediate DNA repair to promote survival of irradiated cells during embryogenesis.
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Affiliation(s)
- Catherine L. Bladen
- Institute of Molecular Medicine and Genetics, Medical College of GeorgiaAugusta, GA 30912, USA
| | - Wai K. Lam
- Institute of Molecular Medicine and Genetics, Medical College of GeorgiaAugusta, GA 30912, USA
| | - William S. Dynan
- Institute of Molecular Medicine and Genetics, Medical College of GeorgiaAugusta, GA 30912, USA
| | - David J. Kozlowski
- Institute of Molecular Medicine and Genetics, Medical College of GeorgiaAugusta, GA 30912, USA
- Department of Cellular Biology and Anatomy, Medical College of GeorgiaAugusta, GA 30912, USA
- To whom correspondence should be addressed. Tel: +1 706 721 8760; Fax: +1 706 721 8752;
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Boothman DA, Reichrath J. New basic science initiatives for improved understanding of radiation-induced multi-organ dysfunction syndrome (MODS). Br J Radiol 2005. [DOI: 10.1259/bjr/19036098] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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Lemon JA, Boreham DR. Workshop on Networking Radiation Sciences in Health, Safety and the Environment. Int J Radiat Biol 2004; 80:83-9. [PMID: 14761853 DOI: 10.1080/09553000310001621428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- J A Lemon
- Medical Physics and Applied Radiation Sciences Unit, McMaster Institute of Applied Radiation Sciences, Nuclear Research Building, 1280 Main St West, Hamilton, Ontario, L8S 1K4 Canada
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Tschaeche A. The LNTH is doing more harm than good. HEALTH PHYSICS 2004; 86:92-93. [PMID: 14695011 DOI: 10.1097/00004032-200401000-00011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
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