1
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Lacombe J, Zenhausern F. Effect of mechanical forces on cellular response to radiation. Radiother Oncol 2022; 176:187-198. [PMID: 36228760 DOI: 10.1016/j.radonc.2022.10.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 08/08/2022] [Accepted: 10/05/2022] [Indexed: 12/14/2022]
Abstract
While the cellular interactions and biochemical signaling has been investigated for long and showed to play a major role in the cell's fate, it is now also evident that mechanical forces continuously applied to the cells in their microenvironment are as important for tissue homeostasis. Mechanical cues are emerging as key regulators of cellular drug response and we aimed to demonstrate in this review that such effects should also be considered vital for the cellular response to radiation. In order to explore the mechanobiology of the radiation response, we reviewed the main mechanoreceptors and transducers, including integrin-mediated adhesion, YAP/TAZ pathways, Wnt/β-catenin signaling, ion channels and G protein-coupled receptors and showed their implication in the modulation of cellular radiosensitivity. We then discussed the current studies that investigated a direct effect of mechanical stress, including extracellular matrix stiffness, shear stress and mechanical strain, on radiation response of cancer and normal cells and showed through preliminary results that such stress effectively can alter cell response after irradiation. However, we also highlighted the limitations of these studies and emphasized some of the contradictory data, demonstrating that the effect of mechanical cues could involve complex interactions and potential crosstalk with numerous cellular processes also affected by irradiation. Overall, mechanical forces alter radiation response and although additional studies are required to deeply understand the underlying mechanisms, these effects should not be neglected in radiation research as they could reveal new fundamental knowledge for predicting radiosensitivity or understanding resistance to radiotherapy.
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Affiliation(s)
- Jerome Lacombe
- Center for Applied NanoBioscience and Medicine, College of Medicine Phoenix, University of Arizona, 475 North 5th Street, Phoenix, AZ 85004, USA; Department of Basic Medical Sciences, College of Medicine Phoenix, University of Arizona, 425 N 5th St, Phoenix, AZ 85004, USA.
| | - Frederic Zenhausern
- Center for Applied NanoBioscience and Medicine, College of Medicine Phoenix, University of Arizona, 475 North 5th Street, Phoenix, AZ 85004, USA; Department of Basic Medical Sciences, College of Medicine Phoenix, University of Arizona, 425 N 5th St, Phoenix, AZ 85004, USA; Department of Biomedical Engineering, College of Engineering, University of Arizona, 1127 E. James E. Rogers Way, Tucson, AZ 85721, USA.
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2
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Suzuki M, Uchihori Y, Kitamura H, Oikawa M, Konishi T. Biologic Impact of Different Ultra-Low-Fluence Irradiations in Human Fibroblasts. Life (Basel) 2020; 10:life10080154. [PMID: 32824801 PMCID: PMC7459653 DOI: 10.3390/life10080154] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 08/14/2020] [Accepted: 08/14/2020] [Indexed: 11/16/2022] Open
Abstract
In this study, we aimed to evaluate the cellular response of healthy human fibroblasts induced by different types of ultra-low-fluence radiations, including gamma rays, neutrons and high linear energy transfer (LET) heavy ions. NB1RGB cells were pretreated with ultra-low-fluence radiations (~0.1 cGy/7-8 h) of 137Cs gamma rays, 241Am-Be neutrons, helium, carbon and iron ions before being exposed to an X-ray-challenging dose (1.5 Gy). Helium (LET = 2.3 keV/µm), carbon (LET = 13.3 keV/µm) and iron (LET = 200 keV/µm) ions were generated with the Heavy Ion Medical Accelerator in Chiba (HIMAC), Japan. No differences in cell death-measured by colony-forming assay-were observed regardless of the radiation type applied. In contrast, mutation frequency, which was detected through cell transformation into 6-thioguanine resistant clones, was 1.9 and 4.0 times higher in cells pretreated with helium and carbon ions, respectively, compared to cells exposed to X-ray-challenging dose alone. Moreover, cells pretreated with iron ions or gamma-rays showed a mutation frequency similar to cells exposed to X-ray-challenging dose alone, while cells pretreated with neutrons had 0.15 times less mutations. These results show that cellular responses triggered by ultra-low-fluence irradiations are radiation-quality dependent. Altogether, this study shows that ultra-low-fluence irradiations with the same level as those reported in the International Space Station are capable of inducing different cellular responses, including radio-adaptive responses triggered by neutrons and genomic instability mediated by high-LET heavy ions, while electromagnetic radiations (gamma rays) seem to have no biologic impact.
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Affiliation(s)
- Masao Suzuki
- Department of Basic Medical Sciences for Radiation Damages, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Chiba 263-8555, Japan
- Correspondence: ; Tel.: +81-43-206-3238
| | - Yukio Uchihori
- Department of Research Planning and Promotion, Quantum Medical Science Directorate, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Chiba 263-8555, Japan;
| | - Hisashi Kitamura
- Department of Radiation Emergency Management, Center for Advanced Radiation Emergency Medicine, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Chiba 263-8555, Japan;
| | - Masakazu Oikawa
- Department of Accelerator and Medical Physics, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Chiba 263-8555, Japan;
| | - Teruaki Konishi
- Single Cell Radiation Biology Group, Institute for Quantum Life Science, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Chiba 263-8555, Japan;
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3
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Werner E, Wang H, Doetsch PW. Role of Pro-inflammatory Cytokines in Radiation-Induced Genomic Instability in Human Bronchial Epithelial Cells. Radiat Res 2015; 184:621-9. [PMID: 26579942 DOI: 10.1667/rr14045.1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Inflammatory cytokines have been implicated in the regulation of radiation-induced genomic instability in the hematopoietic system and have also been shown to induce chronic DNA damage responses in radiation-induced senescence. We have previously shown that human bronchial epithelial cells (HBEC3-KT) have increased genomic instability and IL-8 production persisting at day 7 after exposure to high-LET (600 MeV/nucleon (56)Fe ions) compared to low-LET (320 keV X rays) radiation. Thus, we investigated whether IL-8 induction is part of a broader pro-inflammatory response produced by the epithelial cells in response to damage, which influences genomic instability measured by increased micronuclei and DNA repair foci frequencies. We found that exposure to radiation induced the release of multiple inflammatory cytokines into the media, including GM-CSF, GROα, IL-1α, IL-8 and the inflammation modulator, IL-1 receptor antagonist (IL-1RA). Our results suggest that this is an IL-1α-driven response, because an identical signature was induced by the addition of recombinant IL-1α to nonirradiated cells and functional interference with recombinant IL-1RA (Anakinra) or anti-IL-1α function-blocking antibody, decreased IL-8 production induced by radiation exposure. However, genomic instability was not influenced by this pathway as addition of recombinant IL-1α to naive or irradiated cells or the presence of IL-1 RA under the same conditions as those that interfered with the function of IL-8, did not affect micronuclei or DNA repair foci frequencies measured at day 7 after exposure. While dose-response studies revealed that genomic instability and IL-8 production are the consequences of targeted effects, experiments employing a co-culture transwell system revealed the propagation of pro-inflammatory responses but not genomic instability from irradiated to nonirradiated cells. Collectively, these results point to a cell-autonomous mechanism sustaining radiation-induced genomic instability in this model system and suggest that while molecules associated with these mechanisms could be markers for persisting damage, they reflect two different outcomes.
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Affiliation(s)
- Erica Werner
- a Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia
| | - Huichen Wang
- b Department of Physics, Radiation Institute for Science and Engineering (RaISE), Prairie View A&M University, Prairie View, Texas; and
| | - Paul W Doetsch
- a Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia;,c Departments of Radiation Oncology and Department of Hematology and Medical Oncology, Winship Cancer Institute, Emory University School of Medicine, Atlanta, Georgia
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4
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Belchior A, Balásházy I, Monteiro Gil O, Vaz P, Almeida P. Does the number of irradiated cells influence the spatial distribution of bystander effects? Dose Response 2014; 12:525-39. [PMID: 25552955 DOI: 10.2203/dose-response.14-001.belchior] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
There is growing evidence that the radiation effects at low doses are not adequately described by a simple linear extrapolation from high doses, due, among others, to bystander effects. Though several studies have been published on this topic, the explanation of the mechanisms describing the bystander effects remains unclear. This study aims at understanding how the bystander signals are or can be propagated in the cell culture, namely if the number of irradiated cells influences the bystander response. An A549 cell line was exposed to several doses of α-particles, being the bystander response quantified in two non-irradiated areas. The radius of irradiated areas differs by a factor of 2, and the non-irradiated areas were optimally designed to have the same number of cells. Our results show evidence for bystander effects occurring in cells far away from the irradiated ones, meaning that bystander signals can easily spread throughout the cell culture. Additionally, our study highlights that the damage caused by radiation on the surrounding of irradiated areas could be different according to the number of irradiated cells, i.e., for the same dose value; the overall cellular damage could be different.
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Affiliation(s)
- A Belchior
- IST/CTN, Instituto Superior Técnico, Universidade Técnica de Lisboa, Portugal and Universidade de Lisboa, Instituto de Biofísica e Engenharia Biomédica (IBEB), Portugal
| | - I Balásházy
- Envirionmental Physics Department, Hungarian Academy of Sciences Center for Energy Research, Hungary
| | - O Monteiro Gil
- IST/CTN, Instituto Superior Técnico, Universidade Técnica de Lisboa, Portugal
| | - P Vaz
- IST/CTN, Instituto Superior Técnico, Universidade Técnica de Lisboa, Portugal
| | - P Almeida
- Universidade de Lisboa, Instituto de Biofísica e Engenharia Biomédica (IBEB), Portugal
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5
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Autsavapromporn N, Suzuki M, Funayama T, Usami N, Plante I, Yokota Y, Mutou Y, Ikeda H, Kobayashi K, Kobayashi Y, Uchihori Y, Hei TK, Azzam EI, Murakami T. Gap junction communication and the propagation of bystander effects induced by microbeam irradiation in human fibroblast cultures: the impact of radiation quality. Radiat Res 2013; 180:367-75. [PMID: 23987132 PMCID: PMC4058832 DOI: 10.1667/rr3111.1] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Understanding the mechanisms underlying the bystander effects of low doses/low fluences of low- or high-linear energy transfer (LET) radiation is relevant to radiotherapy and radiation protection. Here, we investigated the role of gap-junction intercellular communication (GJIC) in the propagation of stressful effects in confluent normal human fibroblast cultures wherein only 0.036-0.144% of cells in the population were traversed by primary radiation tracks. Confluent cells were exposed to graded doses from monochromatic 5.35 keV X ray (LET ~6 keV/μm), 18.3 MeV/u carbon ion (LET ~103 keV/μm), 13 MeV/u neon ion (LET ~380 keV/μm) or 11.5 MeV/u argon ion (LET ~1,260 keV/μm) microbeams in the presence or absence of 18-α-glycyrrhetinic acid (AGA), an inhibitor of GJIC. After 4 h incubation at 37°C, the cells were subcultured and assayed for micronucleus (MN) formation. Micronuclei were induced in a greater fraction of cells than expected based on the fraction of cells targeted by primary radiation, and the effect occurred in a dose-dependent manner with any of the radiation sources. Interestingly, MN formation for the heavy-ion microbeam irradiation in the absence of AGA was higher than in its presence at high mean absorbed doses. In contrast, there were no significant differences in cell cultures exposed to X-ray microbeam irradiation in presence or absence of AGA. This showed that the inhibition of GJIC depressed the enhancement of MN formation in bystander cells from cultures exposed to high-LET radiation but not low-LET radiation. Bystander cells recipient of growth medium harvested from 5.35 keV X-irradiated cultures experienced stress manifested in the form of excess micronucleus formation. Together, the results support the involvement of both junctional communication and secreted factor(s) in the propagation of radiation-induced stress to bystander cells. They highlight the important role of radiation quality and dose in the observed effects.
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Affiliation(s)
- Narongchai Autsavapromporn
- Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba, 263-8555, Japan
| | - Masao Suzuki
- Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba, 263-8555, Japan
| | - Tomoo Funayama
- Microbeam Radiation Biology Group, Medical and Biotechnological Application Division, Quantum Beam Sciences Directorate, Japan Atomic Energy Agency, Takasaki, 370-1292, Japan
| | - Noriko Usami
- Photon Factory, High Energy Accelerator Research Organization, Tsukuba, 305-0801, Japan
| | - Ianik Plante
- University Space Research Association, NASA Johnson Space Center, Houston, Texas 77058
| | - Yuichiro Yokota
- Microbeam Radiation Biology Group, Medical and Biotechnological Application Division, Quantum Beam Sciences Directorate, Japan Atomic Energy Agency, Takasaki, 370-1292, Japan
| | - Yasuko Mutou
- Microbeam Radiation Biology Group, Medical and Biotechnological Application Division, Quantum Beam Sciences Directorate, Japan Atomic Energy Agency, Takasaki, 370-1292, Japan
| | - Hiroko Ikeda
- Microbeam Radiation Biology Group, Medical and Biotechnological Application Division, Quantum Beam Sciences Directorate, Japan Atomic Energy Agency, Takasaki, 370-1292, Japan
| | - Katsumi Kobayashi
- Photon Factory, High Energy Accelerator Research Organization, Tsukuba, 305-0801, Japan
| | - Yasuhiko Kobayashi
- Microbeam Radiation Biology Group, Medical and Biotechnological Application Division, Quantum Beam Sciences Directorate, Japan Atomic Energy Agency, Takasaki, 370-1292, Japan
| | - Yukio Uchihori
- Research, Development and Support Center, National Institute of Radiological Sciences, Chiba, 263-8555, Japan
| | - Tom K. Hei
- Center of Radiological Research, Columbia University Medical Center, New York, New York 10032
| | - Edouard I. Azzam
- Department of Radiology, Rutgers University, New Jersey Medical School, Cancer Center, Newark, New Jersey 07103
| | - Takeshi Murakami
- Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba, 263-8555, Japan
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6
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Hei TK, Zhou H, Chai Y, Ponnaiya B, Ivanov VN. Radiation induced non-targeted response: mechanism and potential clinical implications. Curr Mol Pharmacol 2011; 4:96-105. [PMID: 21143185 DOI: 10.2174/1874467211104020096] [Citation(s) in RCA: 165] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/28/2010] [Indexed: 02/06/2023]
Abstract
Generations of students in radiation biology have been taught that heritable biological effects require direct damage to DNA. Radiation-induced non-targeted/bystander effects represent a paradigm shift in our understanding of the radiobiological effects of ionizing radiation in that extranuclear and extracellular effects may also contribute to the biological consequences of exposure to low doses of radiation. Although radiation induced bystander effects have been well documented in a variety of biological systems, including 3D human tissue samples and whole organisms, the mechanism is not known. There is recent evidence that the NF-κB-dependent gene expression of interleukin 8, interleukin 6, cyclooxygenase-2, tumor necrosis factor and interleukin 33 in directly irradiated cells produced the cytokines and prostaglandin E2 with autocrine/paracrine functions, which further activated signaling pathways and induced NF-κB-dependent gene expression in bystander cells. The observations that heritable DNA alterations can be propagated to cells many generations after radiation exposure and that bystander cells exhibit genomic instability in ways similar to directly hit cells indicate that the low dose radiation response is a complex interplay of various modulating factors. The potential implication of the non-targeted response in radiation induced secondary cancer is discussed. A better understanding of the mechanism of the non-targeted effects will be invaluable to assess its clinical relevance and ways in which the bystander phenomenon can be manipulated to increase therapeutic gain in radiotherapy.
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Affiliation(s)
- Tom K Hei
- Center for Radiological Research, Department of Radiation Oncology, Columbia University Medical Center, Vanderbilt Clinic, New York, USA.
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7
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Belchior A, Gil OM, Almeida P, Vaz P. Evaluation of the cytotoxicity and the genotoxicity induced by α radiation in an A549 cell line. RADIAT MEAS 2011. [DOI: 10.1016/j.radmeas.2011.04.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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8
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Blyth BJ, Sykes PJ. Radiation-induced bystander effects: what are they, and how relevant are they to human radiation exposures? Radiat Res 2011; 176:139-57. [PMID: 21631286 DOI: 10.1667/rr2548.1] [Citation(s) in RCA: 149] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The term radiation-induced bystander effect is used to describe radiation-induced biological changes that manifest in unirradiated cells remaining within an irradiated cell population. Despite their failure to fit into the framework of classical radiobiology, radiation-induced bystander effects have entered the mainstream and have become established in the radiobiology vocabulary as a bona fide radiation response. However, there is still no consensus on a precise definition of radiation-induced bystander effects, which currently encompasses a number of distinct signal-mediated effects. These effects are classified here into three classes: bystander effects, abscopal effects and cohort effects. In this review, the data have been evaluated to define, where possible, various features specific to radiation-induced bystander effects, including their timing, range, potency and dependence on dose, dose rate, radiation quality and cell type. The weight of evidence supporting these defining features is discussed in the context of bystander experimental systems that closely replicate realistic human exposure scenarios. Whether the manifestation of bystander effects in vivo is intrinsically limited to particular radiation exposure scenarios is considered. The conditions under which radiation-induced bystander effects are induced in vivo will ultimately determine their impact on radiation-induced carcinogenic risk.
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Affiliation(s)
- Benjamin J Blyth
- Haematology and Genetic Pathology, Flinders University, Bedford Park, South Australia 5042, Australia
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9
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Ojima M, Furutani A, Ban N, Kai M. Persistence of DNA Double-Strand Breaks in Normal Human Cells Induced by Radiation-Induced Bystander Effect. Radiat Res 2011; 175:90-6. [DOI: 10.1667/rr2223.1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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10
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Baskar R. Emerging role of radiation induced bystander effects: Cell communications and carcinogenesis. Genome Integr 2010; 1:13. [PMID: 20831828 PMCID: PMC2949714 DOI: 10.1186/2041-9414-1-13] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2010] [Accepted: 09/12/2010] [Indexed: 02/05/2023] Open
Abstract
Ionizing radiation is an invaluable diagnostic and treatment tool used in various clinical applications. On the other hand, radiation is a known cytotoxic with a potential DNA damaging and carcinogenic effects. However, the biological effects of low and high linear energy transfer (LET) radiations are considerably more complex than previously thought. In the past decade, evidence has mounted for a novel biological phenomenon termed as "bystander effect" (BE), wherein directly irradiated cells transmit damaging signals to non-irradiated cells thereby inducing a response similar to that of irradiated cells. BE can also be induced in various cells irrespective of the type of radiation, and the BE may be more damaging in the longer term than direct radiation exposure. BE is mediated either through gap-junctions or via soluble factors released by irradiated cells. DNA damage response mechanisms represent a vital line of defense against exogenous and endogenous damage caused by radiation and promote two distinct outcomes: survival and the maintenance of genomic stability. The latter is critical for cancer avoidance. Therefore, efforts to understand and modulate the bystander responses will provide new approaches to cancer therapy and prevention. This review overviews the emerging role of BE of low and high LET radiations on the genomic instability of bystander cells and its possible implications for carcinogenesis.
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Affiliation(s)
- Rajamanickam Baskar
- Department of Radiation Oncology, Division of Cellular and Molecular Research, National Cancer Centre, Singapore.
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11
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Leonard BE, Thompson RE, Beecher GC. Human lung cancer risks from radon - part I - influence from bystander effects - a microdose analysis. Dose Response 2010; 9:243-92. [PMID: 21731539 DOI: 10.2203/dose-response.09-057.leonard] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Since the publication of the BEIR VI report in 1999 on health risks from radon, a significant amount of new data has been published showing various mechanisms that may affect the ultimate assessment of radon as a carcinogen, at low domestic and workplace radon levels, in particular the Bystander Effect (BE) and the Adaptive Response radio-protection (AR). We analyzed the microbeam and broadbeam alpha particle data of Miller et al. (1995, 1999), Zhou et al. (2001, 2003, 2004), Nagasawa and Little (1999, 2002), Hei et al. (1999), Sawant et al. (2001a) and found that the shape of the cellular response to alphas is relatively independent of cell species and LET of the alphas. The same alpha particle traversal dose response behavior should be true for human lung tissue exposure to radon progeny alpha particles. In the Bystander Damage Region of the alpha particle response, there is a variation of RBE from about 10 to 35. There is a transition region between the Bystander Damage Region and Direct Damage Region of between one and two microdose alpha particle traversals indicating that perhaps two alpha particle "hits" are necessary to produce the direct damage. Extrapolation of underground miners lung cancer risks to human risks at domestic and workplace levels may not be valid.
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12
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Balduzzi M, Sapora O, Matteucci A, Paradisi S. Modulation of the bystander effects induced by soluble factors in HaCaT cells by different exposure strategies. Radiat Res 2010; 173:779-88. [PMID: 20518657 DOI: 10.1667/rr1835.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The aim of this investigation was to explore whether the occurrence and the magnitude of radiation-induced, medium-mediated bystander effects could be influenced by the time of transfer of secreted bystander factors. HaCaT cells were exposed to 0.1 and 1.0 Gy of gamma radiation. These doses did not induce a significant reduction in the clonogenic survival of irradiated cells compared to controls. Bystander cells either were co-cultured with irradiated cells or received medium from irradiated cells. The bystander effects analyzed included end points related to survival (clonogenic potential and cell proliferation) and DNA damage (micronucleus induction and gamma-H2AX formation). The bystander effects we investigated either were lacking or varied from potentially protective to detrimental responses in relation to the dose of radiation and the time between irradiation of donor cells and bystander exposure. Our results suggest that the experimental time schedule is important for both the occurrence and the detection of bystander effects in vitro.
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Affiliation(s)
- Maria Balduzzi
- Section of Toxicology and Biomedical Sciences, ENEA CR Casaccia, 00123 Rome, Italy.
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13
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Sowa MB, Goetz W, Baulch JE, Pyles DN, Dziegielewski J, Yovino S, Snyder AR, de Toledo SM, Azzam EI, Morgan WF. Lack of evidence for low-LET radiation induced bystander response in normal human fibroblasts and colon carcinoma cells. Int J Radiat Biol 2010; 86:102-13. [PMID: 20148696 DOI: 10.3109/09553000903419957] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE To investigate radiation-induced bystander responses and to determine the role of gap junction intercellular communication and the radiation environment in propagating this response. MATERIALS AND METHODS We used medium transfer and targeted irradiation to examine radiation-induced bystander effects in primary human fibroblast (AG01522) and human colon carcinoma (RKO36) cells. We examined the effect of variables such as gap junction intercellular communication, linear energy transfer (LET), and the role of the radiation environment in non-targeted responses. Endpoints included clonogenic survival, micronucleus formation and foci formation at histone 2AX over doses ranging from 10-100 cGy. RESULTS The results showed no evidence of a low-LET radiation-induced bystander response for the endpoints of clonogenic survival and induction of DNA damage. Nor did we see evidence of a high-LET, Fe ion radiation (1 GeV/n) induced bystander effect. However, direct comparison for 3.2 MeV alpha-particle exposures showed a statistically significant medium transfer bystander effect for this high-LET radiation. CONCLUSIONS From our results, it is evident that there are many confounding factors influencing bystander responses as reported in the literature. Our observations reflect the inherent variability in biological systems and the difficulties in extrapolating from in vitro models to radiation risks in humans.
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Affiliation(s)
- Marianne B Sowa
- Molecular and Cellular Biology, Pacific Northwest National Laboratory, Richland, Washington 99354, USA.
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14
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Chapman KL, Kelly JW, Lee R, Goodwin EH, Kadhim MA. Tracking genomic instability within irradiated and bystander populations. J Pharm Pharmacol 2010; 60:959-68. [DOI: 10.1211/jpp.60.8.0003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Abstract
Over the past two decades, our understanding of radiation biology has undergone a fundamental shift in paradigms away from deterministic ‘hit-effect’ relationships and towards complex ongoing ‘cellular responses’. These responses include now familiar, but still poorly understood, phenomena associated with radiation exposure such as genomic instability and bystander effects. Although these responses share some common features (e.g. they occur at high frequency following very low doses, are heterogeneous in their induction and are observed at time points far removed from the initial radiation exposure), the precise relationship between genomic instability and bystander effects remains to be elucidated. This review will provide a synthesis of the known, and proposed, interrelationships among irradiated and bystander cellular responses to radiation. It also discusses our current experimental approach for gaining a clearer understanding of the relationship between damage induction and long-term effects in both irradiated and bystander cells.
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Affiliation(s)
- Kim L Chapman
- School of Life Sciences, Oxford Brookes University, Oxford, OX3 0BP, UK
| | - James W Kelly
- School of Life Sciences, Oxford Brookes University, Oxford, OX3 0BP, UK
| | - Ryonfa Lee
- Gesellschaft für Schwerionenforschung mbH (GSI), Planckstr. 1, 64291 Darmstadt, Germany
| | - Edwin H Goodwin
- Bioscience Division, Los Alamos National Laboratory, MS M-888, Los Alamos, NM 87545, USA
| | - Munira A Kadhim
- School of Life Sciences, Oxford Brookes University, Oxford, OX3 0BP, UK
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15
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Chakraborty A, Held KD, Prise KM, Liber HL, Redmond RW. Bystander effects induced by diffusing mediators after photodynamic stress. Radiat Res 2009; 172:74-81. [PMID: 19580509 DOI: 10.1667/rr1669.1] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The bystander effect, whereby cells that are not traversed by ionizing radiation exhibit various responses when in proximity to irradiated cells, is well documented in the field of radiation biology, Here we demonstrate that considerable bystander responses are also observed after photodynamic stress using the membrane-localizing dye deuteroporphyrin (DP). Using cells of a WTK1 human lymphoblastoid cell line in suspension and a transwell insert system that precludes contact between targeted and bystander cells, we have shown that the bystander signaling is mediated by diffusing species. The extranuclear localization of the photosensitizer used suggests that primary DNA damage is not the trigger for initiating these bystander responses, which include elevated oxidative stress, DNA damage (micronucleus formation), mutagenesis and decreased clonogenic survival. In addition, oxidative stress in the bystander population was reduced by the presence of the membrane antioxidant vitamin E in the targeted cells, suggesting that lipid peroxidation may play a key role in mediating these bystander effects. The fluence responses for these bystander effects are non-linear, with larger effects seen at lower fluences and toxicity to the target cell population. Hence, when considering outcomes of photodynamic action in cells and tissue, bystander effects may be significant, especially at sublethal fluences.
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Affiliation(s)
- Asima Chakraborty
- Wellman Center for Photomedicine, Harvard Medical School, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
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Banaz-Yaşar F, Tischka R, Iliakis G, Winterhager E, Gellhaus A. Cell Line Specific Modulation of Connexin43 Expression after Exposure to Ionizing Radiation. ACTA ACUST UNITED AC 2009; 12:249-59. [PMID: 16531320 DOI: 10.1080/15419060500514101] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Gap junctional intercellular communication plays a significant role in mediating radiation-induced bystander effects. However, the level of Cx43 itself is influenced by ionizing radiation, which could modify the bystander effect. Here we have investigated several cell lines for the modulation of Cx43 expression 24 h after irradiation with 5 Gy X-rays. The mouse endothelial cell line bEnd3 revealed a significantly elevated level of Cx43 already 15 min after exposure to X-rays, whereas human hybrid endothelial cells (EA.hy926) exhibited a transient downregulation of Cx43 mRNA. No obvious changes in the communication properties of the different cell lines could be observed after irradiation. The communication-deficient malignant human trophoblast cell line Jeg3 stably transfected with Cx43 did not reveal any induction of endogenous nor alteration in the exogenous Cx43 transcript level upon exposure to 5 Gy. Taken together, our data show a cell line specific modulation of Cx43 expression after exposure to X-rays.
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Lyng FM, Maguire P, Kilmurray N, Mothersill C, Shao C, Folkard M, Prise KM. Apoptosis is initiated in human keratinocytes exposed to signalling factors from microbeam irradiated cells. Int J Radiat Biol 2009; 82:393-9. [PMID: 16846974 DOI: 10.1080/09553000600803904] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
PURPOSE There is now no doubt that bystander signalling from irradiated cells occurs and causes a variety of responses in cells not targeted by the ionizing track. However, the mechanisms underlying these processes are unknown and the relevance to radiotherapy and risk assessment remains controversial. Previous research by our laboratory has shown bystander effects in a human keratinocyte cell line, HPV-G cells, exposed to medium from gamma irradiated HPV-G cells. The aim of this work was to investigate if similar mechanisms to those identified in medium transfer experiments occurred in these HPV-G cells when they are in the vicinity of microbeam irradiated cells. Demonstration of a commonality of mechanisms would support the idea that the process is not artifactual. MATERIALS AND METHODS HPV-G cells were plated as two separate populations on mylar dishes. One population was directly irradiated using a charged particle microbeam (1 - 10 protons). The other population was not irradiated. Bystander factor-induced apoptosis was investigated in both populations following treatment by monitoring the levels of reactive oxygen species and mitochondrial membrane potential using fluorescent probes. Expression of the anti-apoptotic protein, bcl-2, and cytochrome c were determined, as well as apoptosis levels. RESULTS Microbeam irradiation induced increases in reactive oxygen species and decreases in mitochondrial membrane potential at 6 h post-exposure, increased expression of bcl-2 and cytochrome c release at 6.5 h and increased apoptosis at 24 h. CONCLUSION This study shows that similar bystander signalling pathways leading to apoptosis are induced following microbeam irradiation and following medium transfer. This demonstrates that the mechanisms involved are common across different radiation qualities and conditions and indicates that they may be relevant in vivo.
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Affiliation(s)
- Fiona M Lyng
- Radiation and Environmental Science Centre, Focas Institute, Dublin Institute of Technology, Dublin, Ireland.
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18
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Frankenberg D, Greif KD, Giesen U. Radiation response of primary human skin fibroblasts and their bystander cells after exposure to counted particles at low and high LET. Int J Radiat Biol 2009; 82:59-67. [PMID: 16546904 DOI: 10.1080/09553000600582979] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
PURPOSE To investigate the dependence of bystander effects on linear energy transfer (LET) in the low dose region. MATERIALS AND METHODS The single-ion microbeam of the Physikalisch-Technische Bundesanstalt (PTB) was used to irradiate confluent primary human skin fibroblasts. Cells plated on a special irradiation dish were targeted with 10 MeV protons (LET 4.7 keV/microm) and 4.5 MeV a-particles (LET 100 keV/microm). During exposure, the cells were confluent allowing signal transfers through both gap junctions and diffusion. RESULTS For 10 MeV protons the clonogenic capability was significantly higher after exposure to 70 protons (0.31 Gy) compared with unirradiated cells. For higher doses the survival curve was exponential. Exposure of only 10% of all nuclei resulted in a similar radiation response in the low dose region. For higher doses up to 2.2 Gy no cell killing was observed. For 4.5 MeV alpha-particles an exponential survival curve was obtained. Irradiation of only 10% of all cell nuclei resulted in an survival curve as had been expected in the absence of any bystander effect. CONCLUSION The type and extent of bystander effects turned out to be dependent on the particles' LET and are likely to depend also on the cell line used and the techniques applied.
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Kanasugi Y, Hamada N, Wada S, Funayama T, Sakashita T, Kakizaki T, Kobayashi Y, Takakura K. Role of DNA-PKcs in the bystander effect after low- or high-LET irradiation. Int J Radiat Biol 2009; 83:73-80. [PMID: 17357428 DOI: 10.1080/09553000601121116] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
PURPOSE To investigate the role of the catalytic subunit of DNA-dependent protein kinase (DNA-PKcs) in the medium-mediated bystander effect for chromosomal aberrations induced by low-linear energy transfer (LET) X-rays and high-LET heavy ions in normal human fibroblast cells. MATERIALS AND METHODS The recipient cells were treated for 12 h with conditioned medium, which was harvested from donor cells at 24 h after exposure to 10 Gy of soft X-rays (5 keV/microm) and 20Ne ions (437 keV/microm), followed by analyses of chromosome aberrations in recipient cells with premature chromosome condensation methods. To examine the role of DNA-PKcs and nitric oxide (NO), cells were treated with its inhibitor LY294002 (LY) and its scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide (c-PTIO), respectively. RESULTS Increased frequency of chromosome aberrations in recipient cells treated with conditioned medium from irradiated but not from un-irradiated donor cells was observed which was independent of radiation type. Bystander induction of chromosome aberrations in recipient cells was mitigated when donor cells were treated with LY before irradiation and with c-PTIO after irradiation, and was enhanced when recipient cells were treated with LY before treatment of recipient cells with conditioned medium from irradiated donor cells. CONCLUSION Irradiated normal human cells secrete NO and other molecules which in turn transmit radiation signals to unirradiated bystander cells, leading to the induction of bystander chromosome aberrations partially repairable by DNA-PKcs-mediated DNA damage repair machinery, such as non-homologous end-joining repair pathways.
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Affiliation(s)
- Yuichi Kanasugi
- Physics Department, International Christian University, Tokyo, Japan
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20
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Chen S, Zhao Y, Zhao G, Han W, Bao L, Yu KN, Wu L. Up-regulation of ROS by mitochondria-dependent bystander signaling contributes to genotoxicity of bystander effects. Mutat Res 2009; 666:68-73. [PMID: 19393669 DOI: 10.1016/j.mrfmmm.2009.04.006] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2008] [Revised: 03/13/2009] [Accepted: 04/15/2009] [Indexed: 05/27/2023]
Abstract
Genomic instability can be observed in bystander cells. However, the underlying mechanism(s) is still relatively unclear. In a previous study, we found that irradiated cells released mitochondria-dependent intracellular factor(s) which could lead to bystander gamma-H2AX induction. In this paper, we used normal (rho(+)) and mtDNA-depleted (rho(0)) human-hamster hybrid cells to investigate mitochondrial effects on the genotoxicity in bystander effect through medium transfer experiments. Through the detection of DNA double-strand breaks with gamma-H2AX, we found that the fraction of gamma-H2AX positive cells changed with time when irradiation conditioned cell medium (ICCM) were harvested. ICCM harvested from irradiated rho(+) cells at 10 min post-irradiation (rho(+) ICCM(10 min)) caused larger increases of bystander gamma-H2AX induction comparing to rho(0) ICCM(10 min), which only caused a slight increase of bystander gamma-H2AX induction. The rho(+) ICCM(10 min) could also result in the up-regulation of ROS production (increased by 35% at 10 min), while there was no significant increase in cells treated with rho(0) ICCM(10 min). We treated cells with dimethyl sulfoxide (DMSO), the scavenger of ROS, and quenched gamma-H2AX induction by rho(+) ICCM. Furthermore, after the medium had been transferred and the cells were continuously cultured for 7 days, we found significantly increased CD59(-) gene loci mutation (increased by 45.9%) and delayed cell death in the progeny of rho(+) ICCM-treated bystander cells. In conclusion, the work presented here suggested that up-regulation of the mitochondria-dependent ROS might be very important in mediating genotoxicity of bystander effects.
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Affiliation(s)
- Shaopeng Chen
- Key Laboratory of Ion Beam Bioengineering, Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, People's Republic of China
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21
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Vines AM, Lyng FM, McClean B, Seymour C, Mothersill CE. Bystander effect induced changes in apoptosis related proteins and terminal differentiation in in vitro murine bladder cultures. Int J Radiat Biol 2009; 85:48-56. [PMID: 19205984 DOI: 10.1080/09553000802635047] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
PURPOSE Radiation-induced bystander effects are now an established phenomenon seen in numerous cell and tissue culture models. The aim of this investigation was to examine the bystander signal and response in a multicellular primary tissue culture system in vitro. METHODS AND MATERIALS Murine bladder samples were explanted and directly exposed to gamma radiation, or treated with irradiated tissue conditioned medium (ITCM) generated from the directly irradiated cultures. RESULTS Results indicated that there was a strong bystander signal produced by the tissue that caused both dose-dependent and -independent changes in the ITCM treated tissue. Significantly increased B-cell lymphoma 2 (Bcl2) expression was noted after treatment with 0.5Gy and 5Gy ITCM (approximately 80%), while dose-dependent changes were observed in c-myelocytomatosis (cMyc) (39.48% at 0.5 Gy ITCM, 81.28% at 5 Gy ITCM) and the terminal differentiation marker uroplakin III (17.88% at 0.5 Gy). Nuclear fragmentation was also significantly increased at both doses of ITCM. CONCLUSION These data suggest that the bystander signal produced in a multicellular environment induces complex changes in the ITCM-treated culture, and that these changes are reflective of a coordinated response to maintain integrity throughout the tissue.
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Affiliation(s)
- A M Vines
- Radiation and Environmental Science Centre, Focas Institute, Dublin Institute of Technology, Dublin.
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22
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Schmid E, Roos H. Influence of the bystander phenomenon on the chromosome aberration pattern in human lymphocytes induced by in vitro alpha-particle exposure. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2009; 48:181-187. [PMID: 19066927 DOI: 10.1007/s00411-008-0204-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2008] [Accepted: 11/21/2008] [Indexed: 05/27/2023]
Abstract
A recent publication on both chromosome-type and chromatid-type aberrations in lymphocytes of patients during treatment with radium-224 for ankylosing spondilitis has revived the question of whether the chromatid-type aberrations may be the consequence of factors released by irradiated cells. Therefore, the aim of the present study was to investigate the influence of such a bystander phenomenon on the chromosome aberration pattern of lymphocytes. Monolayers of human lymphocytes were irradiated with 1 Gy of alpha-particles from an americium-241 source in the absence or presence of whole blood, autologous plasma or culture medium. In the presence of any liquid covering the monolayer during irradiation, the chromatid-type aberrations were, contrary to expectation, elevated. Whereas the intercellular distribution of dicentrics was significantly overdispersed, the chromatid-type aberrations showed a regular dispersion. It can be concluded that the enhanced frequency of chromatid aberrations is the result of a damage signal or a bystander phenomenon released by irradiated cells.
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Affiliation(s)
- Ernst Schmid
- Radiobiological Institute, University of Munich, Schillerstrasse 42, 80336 Munich, Germany.
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Fakir H, Hofmann W, Tan WY, Sachs RK. Triggering-Response Model for Radiation-Induced Bystander Effects. Radiat Res 2009; 171:320-31. [DOI: 10.1667/rr1293.1] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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24
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Groesser T, Cooper B, Rydberg B. Lack of Bystander Effects from High-LET Radiation for Early Cytogenetic End Points. Radiat Res 2008; 170:794-802. [DOI: 10.1667/rr1458.1] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2008] [Accepted: 07/28/2008] [Indexed: 11/03/2022]
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Hei TK, Zhou H, Ivanov VN, Hong M, Lieberman HB, Brenner DJ, Amundson SA, Geard CR. Mechanism of radiation-induced bystander effects: a unifying model. J Pharm Pharmacol 2008; 60:943-50. [PMID: 18644187 DOI: 10.1211/jpp.60.8.0001] [Citation(s) in RCA: 245] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The radiation-induced bystander effect represents a paradigm shift in our understanding of the radiobiological effects of ionizing radiation, in that extranuclear and extracellular events may also contribute to the final biological consequences of exposure to low doses of radiation. Although radiation-induced bystander effects have been well documented in a variety of biological systems, the mechanism is not known. It is likely that multiple pathways are involved in the bystander phenomenon, and different cell types respond differently to bystander signalling. Using cDNA microarrays, a number of cellular signalling genes, including cyclooxygenase-2 (COX-2), have been shown to be causally linked to the bystander phenomenon. The observation that inhibition of the phosphorylation of extracellular signal-related kinase (ERK) suppressed the bystander response further confirmed the important role of the mitogen-activated protein kinase (MAPK) signalling cascade in the bystander process. Furthermore, cells deficient in mitochondrial DNA showed a significantly reduced response to bystander signalling, suggesting a functional role of mitochondria in the signalling process. Inhibitors of nitric oxide (NO) synthase (NOS) and mitochondrial calcium uptake provided evidence that NO and calcium signalling are part of the signalling cascade. The bystander observations imply that the relevant target for various radiobiological endpoints is larger than an individual cell. A better understanding of the cellular and molecular mechanisms of the bystander phenomenon, together with evidence of their occurrence in-vivo, will allow us to formulate a more accurate model for assessing the health effects of low doses of ionizing radiation.
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Affiliation(s)
- Tom K Hei
- Center for Radiological Research, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA.
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26
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Kovalchuk O, Baulch JE. Epigenetic changes and nontargeted radiation effects--is there a link? ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2008; 49:16-25. [PMID: 18172877 DOI: 10.1002/em.20361] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
It is now well accepted that the effects of ionizing radiation (IR) exposure can be noticed far beyond the borders of the directly irradiated tissue. IR can affect neighboring cells in the proximity, giving rise to a bystander effect. IR effects can also span several generations and influence the progeny of exposed parents, leading to transgeneration effects. Bystander and transgeneration IR effects are linked to the phenomenon of the IR-induced genome instability that manifests itself as chromosome aberrations, gene mutations, late cell death, and aneuploidy. While the occurrence of the above-mentioned phenomena is well documented, the exact mechanisms that lead to their development have still to be delineated. Evidence suggests that the IR-induced genome instability, bystander, and transgeneration effects may be epigenetically mediated. The epigenetic changes encompass DNA methylation, histone modification, and RNA-associated silencing. Recent studies demonstrated that IR exposure alters epigenetic parameters in the directly exposed tissues and in the distant bystander tissues. Transgeneration radiation effects were also proposed to be of an epigenetic nature. We will discuss the role of the epigenetic mechanisms in radiation responses, bystander effects, and transgeneration effects.
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Affiliation(s)
- Olga Kovalchuk
- Department of Biological Sciences, University of Lethbridge, Alberta, Canada.
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Hamada N, Matsumoto H, Hara T, Kobayashi Y. Intercellular and intracellular signaling pathways mediating ionizing radiation-induced bystander effects. JOURNAL OF RADIATION RESEARCH 2007; 48:87-95. [PMID: 17327686 DOI: 10.1269/jrr.06084] [Citation(s) in RCA: 125] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
A rapidly growing body of experimental evidence indicates that ionizing radiation induces biological effects in non-irradiated bystander cells that have received signals from adjacent or distant irradiated cells. This phenomenon, which has been termed the ionizing radiation-induced bystander effect, challenges the long-standing paradigm that radiation traversal through the nucleus of a cell is a prerequisite to elicit genetic damage or a biological response. Bystander effects have been observed in a number of experimental systems, and cells whose nucleus or cytoplasm is irradiated exert bystander responses. Bystander cells manifest a multitude of biological consequences, such as genetic and epigenetic changes, alterations in gene expression, activation of signal transduction pathways, and delayed effects in their progeny. Several mediating mechanisms have been proposed. These involve gap junction-mediated intercellular communication, secreted soluble factors, oxidative metabolism, plasma membrane-bound lipid rafts, and calcium fluxes. This paper reviews briefly the current knowledge of the bystander effect with a focus on proposed mechanisms. The potential benefit of bystander effects to cancer radiotherapy will also be discussed.
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Affiliation(s)
- Nobuyuki Hamada
- Department of Quantum Biology, Division of Bioregulatory Medicine, Gunma University Graduate School of Medicine, Maebashi, Japan.
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28
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Bowler DA, Moore SR, Macdonald DA, Smyth SH, Clapham P, Kadhim MA. Bystander-mediated genomic instability after high LET radiation in murine primary haemopoietic stem cells. Mutat Res 2006; 597:50-61. [PMID: 16414086 DOI: 10.1016/j.mrfmmm.2005.04.025] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2005] [Revised: 03/30/2005] [Accepted: 04/08/2005] [Indexed: 05/06/2023]
Abstract
Communication between irradiated and unirradiated (bystander) cells can result in responses in unirradiated cells that are similar to responses in their irradiated counterparts. The purpose of the current experiment was to test the hypothesis that bystander responses will be similarly induced in primary murine stem cells under different cell culture conditions. The experimental systems used here, co-culture and media transfer, are similar in that they both restrict communication between irradiated and bystander cells to media borne factors, but are distinct in that with the media transfer technique, cells can only communicate after irradiation, and with co-culture, cells can communication before, during and after irradiation. In this set of parallel experiments, cell type, biological endpoint, and radiation quality and dose, were kept constant. In both experimental systems, clonogenic survival was significantly decreased in all groups, whether irradiated or bystander, suggesting a substantial contribution of bystander effects (BE) to cell killing. Genomic instability (GI) was induced under all radiation and bystander conditions in both experiments, including a situation where unirradiated cells were incubated with media that had been conditioned for 24h with irradiated cells. The appearance of delayed aberrations (genomic instability) 10-13 population doublings after irradiation was similar to the level of initial chromosomal damage, suggesting that the bystander factor is able to induce chromosomal alterations soon after irradiation. Whether these early alterations are related to those observed at later timepoints remains unknown. These results suggest that genomic instability may be significantly induced in a bystander cell population whether or not cells communicate during irradiation.
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Affiliation(s)
- Deborah A Bowler
- Radiation and Genome Stability Unit, Medical Research Council, Harwell, Didcot Oxfordshire OX11 0RD, UK
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Mothersill C, Seymour RJ, Seymour CB. Increased radiosensitivity in cells of two human cell lines treated with bystander medium from irradiated repair-deficient cells. Radiat Res 2006; 165:26-34. [PMID: 16392959 DOI: 10.1667/rr3488.1] [Citation(s) in RCA: 41] [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
Radiation-induced bystander factors have been shown to be more toxic if they are from medium harvested from irradiated repair-deficient cells. The aim of this study was to test the hypothesis that the radiosensitivity of repair-proficient cells can be increased by exposing them to medium-borne factors harvested from sensitive cells and vice versa. Cells from a mismatch repair (MMR)-deficient cell line (Raji 10) with a sensitive response to radiation or the wild-type parent cell line were irradiated to 0.5 Gy gamma rays and then monitored for growth rate in their own medium or in the alternative conditioned medium. In other experiments, cells or conditioned medium were added to reporter cells (HPV-G, which are relatively sensitive keratinocytes, or highly radioresistant HT29 cells). The subsequent responses of the two cell lines to a 0.5-Gy dose of (60)Co gamma rays were measured. The results show that prior exposure of resistant cells to medium from irradiated sensitive cells reduced the clonogenic survival of the subsequently irradiated resistant cells. The reverse is also true. Measurement of the apoptosis index and BCL2 expression confirmed that the harvested medium was capable of modulating apoptosis after irradiation. This may have important applications in tumor therapy and also in the understanding of mechanisms involved in induction of adaptive responses.
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Affiliation(s)
- C Mothersill
- Medical Physics and Applied Radiation Sciences Unit, McMaster University, Hamilton, Ontario L8S 4K1, Canada.
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30
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Wang R, Coderre JA. A Bystander Effect in Alpha-Particle Irradiations of Human Prostate Tumor Cells. Radiat Res 2005; 164:711-22. [PMID: 16296877 DOI: 10.1667/3475.1] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Alpha-particle exposures were used to determine whether cells of the human prostate carcinoma cell line DU-145 can produce and respond to a bystander effect signal. An apparatus for alpha-particle irradiation of cells growing as a monolayer on a 1.4-microm-thick Mylar membrane directly above an 241Am alpha-particle source was constructed and calibrated. At the cell irradiation position, the alpha-particle fluence was 998 counts/mm2 s(-1), the average alpha-particle energy was 3.14 MeV, and the average linear energy transfer was 128 keV/microm. The average dose rate to the cells growing on the Mylar surface was 1.2 Gy/min. A co-culture system was used to examine bystander effects transmitted through the medium from the directly targeted cells to tumor cells growing on an insert well beyond the range of the alpha particles. Alpha-particle doses from 0.1 to 6.0 Gy to the targeted cells on the Mylar membrane, followed by a 2-h co-incubation of the cells on the insert in the irradiated medium above the irradiated cells, all caused an approximately 50% increase in micronucleus formation in the nontargeted co-cultured cells. Addition of the radical scavenger DMSO to the medium during the irradiation and the 2-h postirradiation incubation period completely blocked the bystander effect, whereas addition of a nitric oxide scavenger had no effect. Irradiation of medium containing serum, followed by a 2-h incubation, caused no bystander effect in the co-cultured cells. When the co-cultured cells on the insert were placed into the irradiated medium above the directly targeted cells immediately (approximately 1 min) after the irradiation and co-incubated for 2 h, there was no bystander effect. These data indicate that the observed bystander effect requires that the co-cultured cells be present in the medium during the irradiation of the directly targeted cells and suggest the involvement of a short-lived radical species.
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Affiliation(s)
- Rong Wang
- Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge 02139, USA
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Sokolov MV, Smilenov LB, Hall EJ, Panyutin IG, Bonner WM, Sedelnikova OA. Ionizing radiation induces DNA double-strand breaks in bystander primary human fibroblasts. Oncogene 2005; 24:7257-65. [PMID: 16170376 DOI: 10.1038/sj.onc.1208886] [Citation(s) in RCA: 177] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
That irradiated cells affect their unirradiated 'bystander' neighbors is evidenced by reports of increased clonogenic mortality, genomic instability, and expression of DNA-repair genes in the bystander cell populations. The mechanisms underlying the bystander effect are obscure, but genomic instability suggests DNA double-strand breaks (DSBs) may be involved. Formation of DSBs induces the phosphorylation of the tumor suppressor protein, histone H2AX and this phosphorylated form, named gamma-H2AX, forms foci at DSB sites. Here we report that irradiation of target cells induces gamma-H2AX focus formation in bystander cell populations. The effect is manifested by increases in the fraction of cells in a population that contains multiple gamma-H2AX foci. After 18 h coculture with cells irradiated with 20 alpha-particles, the fraction of bystander cells with multiple foci increased 3.7-fold. Similar changes occurred in bystander populations mixed and grown with cells irradiated with gamma-rays, and in cultures containing media conditioned on gamma-irradiated cells. DNA DSB repair proteins accumulated at gamma-H2AX foci, indicating that they are sites of DNA DSB repair. Lindane, which blocks gap-junctions, prevented the bystander effect in mixing but not in media transfer protocols, while c-PTIO and aminoguanidine, which lower nitric oxide levels, prevented the bystander effect in both protocols. Thus, multiple mechanisms may be involved in transmitting bystander effects. These studies show that H2AX phosphorylation is an early step in the bystander effect and that the DNA DSBs underlying gamma-H2AX focus formation may be responsible for its downstream manifestations.
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Affiliation(s)
- Mykyta V Sokolov
- Department of Nuclear Medicine, Clinical Center, NIH, 9000 Rockville Pike, Bethesda, MD 20892, USA
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Belyakov OV, Mitchell SA, Parikh D, Randers-Pehrson G, Marino SA, Amundson SA, Geard CR, Brenner DJ. Biological effects in unirradiated human tissue induced by radiation damage up to 1 mm away. Proc Natl Acad Sci U S A 2005; 102:14203-8. [PMID: 16162670 PMCID: PMC1202386 DOI: 10.1073/pnas.0505020102] [Citation(s) in RCA: 209] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A central tenet in understanding the biological effects of ionizing radiation has been that the initially affected cells were directly damaged by the radiation. By contrast, evidence has emerged concerning "bystander" responses involving damage to nearby cells that were not themselves directly traversed by the radiation. These long-range effects are of interest both mechanistically and for assessing risks from low-dose exposures, where only a small proportion of cells are directly hit. Bystander effects have been observed largely by using single-cell in vitro systems that do not have realistic multicellular morphology; no studies have as yet been reported in three-dimensional, normal human tissue. Given that the bystander phenomenon must involve cell-to-cell interactions, the relevance of such single-cell in vitro studies is questionable, and thus the significance of bystander responses for human health has remained unclear. Here, we describe bystander responses in a three-dimensional, normal human-tissue system. Endpoints were induction of micronucleated and apoptotic cells. A charged-particle microbeam was used, allowing irradiation of cells in defined locations in the tissue yet guaranteeing that no cells located more than a few micrometers away receive any radiation exposure. Unirradiated cells up to 1 mm distant from irradiated cells showed a significant enhancement in effect over background, with an average increase in effect of 1.7-fold for micronuclei and 2.8-fold for apoptosis. The surprisingly long range of bystander signals in human tissue suggests that bystander responses may be important in extrapolating radiation risk estimates from epidemiologically accessible doses down to very low doses where nonhit bystander cells will predominate.
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Affiliation(s)
- Oleg V Belyakov
- Center for Radiological Research, Columbia University, New York, NY 10032, USA.
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Maguire P, Mothersill C, Seymour C, Lyng FM. Medium from irradiated cells induces dose-dependent mitochondrial changes and BCL2 responses in unirradiated human keratinocytes. Radiat Res 2005; 163:384-90. [PMID: 15799693 DOI: 10.1667/rr3325] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Exposure of unirradiated human keratinocytes to irradiated cell conditioned medium (ICCM) is known to cause a cascade of events that leads to reproductive death and apoptosis. This study investigates the effect of ICCM on clonogenic survival, mitochondrial mass and BCL2 expression in unirradiated keratinocytes. Exposure to 5 mGy, 0.5 Gy and 5 Gy ICCM resulted in a significant decrease in clonogenic survival. Human keratinocytes incubated with ICCM containing an antioxidant, N-acetylcysteine, showed no significant decrease in clonogenic survival. HPV-G cells incubated with ICCM containing a caspase 9 inhibitor showed no significant decrease in clonogenic survival when the ICCM dose was < or =0.5 Gy. A significant increase in mitochondrial mass per cell was observed after exposure to 5 mGy and 0.5 Gy ICCM. A change in the distribution of the mitochondria from a diffuse cytoplasmic distribution to a more densely concentrated perinuclear distribution was also observed at these doses. No significant increase in mitochondrial mass or change in distribution of the mitochondria was found for 5 Gy ICCM. Low BCL2 expression was observed in HPV-G cells exposed to 5 mGy or 0.5 Gy ICCM, whereas a large significant increase in BCL2 expression was observed in cells exposed to 5 Gy ICCM. This study has shown that low-dose irradiation can cause cells to produce medium-borne signals that can cause mitochondrial changes and the induction of BCL2 expression in unirradiated HPV-G cells. The dose dependence of the mitochondrial changes and BCL2 expression suggests that the mechanisms may be aimed at control of response to radiation at the population level through signaling pathways.
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Affiliation(s)
- Paula Maguire
- Radiation and Environmental Science Centre, Dublin Institute of Technology, Dublin, Ireland.
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Shao C, Folkard M, Michael BD, Prise KM. Bystander signaling between glioma cells and fibroblasts targeted with counted particles. Int J Cancer 2005; 116:45-51. [PMID: 15756683 DOI: 10.1002/ijc.21003] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Radiation-induced bystander effects may play an important role in cancer risks associated with environmental, occupational and medical exposures and they may also present a therapeutic opportunity to modulate the efficacy of radiotherapy. However, the mechanisms underpinning these responses between tumor and normal cells are poorly understood. Using a microbeam, we investigated interactions between T98G malignant glioma cells and AG01522 normal fibroblasts by targeting cells through their nuclei in one population, then detecting cellular responses in the other co-cultured non-irradiated population. It was found that when a fraction of cells was individually irradiated with exactly 1 or 5 helium particles ((3)He(2+)), the yield of micronuclei (MN) in the non-irradiated population was significantly increased. This increase was not related to the fraction of cells targeted or the number of particles delivered to those cells. Even when one cell was targeted with a single (3)He(2+), the induction of MN in the bystander non-irradiated population could be increased by 79% for AG01522 and 28% for T98G. Furthermore, studies showed that nitric oxide (NO) and reactive oxygen species (ROS) were involved in these bystander responses. Following nuclear irradiation in only 1% of cells, the NO level in the T98G population was increased by 31% and the ROS level in the AG0 population was increased by 18%. Treatment of cultures with 2-(4-carboxyphenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide (c-PTIO), an NO scavenger, abolished the bystander MN induction in non-irradiated AG01522 cells but only partially in non-irradiated T98G cells, and this could be eliminated by treatment with either DMSO or antioxidants. Our findings indicate that differential mechanisms involving NO and ROS signaling factors play a role in bystander responses generated from targeted T98G glioma and AG0 fibroblasts, respectively. These bystander interactions suggest that a mechanistic control of the bystander effect could be of benefit to radiotherapy.
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Affiliation(s)
- Chunlin Shao
- Gray Cancer Institute, Mount Vernon Hospital, Northwood, Middlesex, United Kingdom
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Hei TK, Persaud R, Zhou H, Suzuki M. Genotoxicity in the eyes of bystander cells. Mutat Res 2004; 568:111-20. [PMID: 15530544 DOI: 10.1016/j.mrfmmm.2004.07.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2004] [Revised: 07/02/2004] [Accepted: 07/02/2004] [Indexed: 05/01/2023]
Abstract
The controversial use of a linear, no threshold extrapolation model for low dose risk assessment has become even more so in light of the recent reports on the bystander phenomenon. The answer to the question as to which of the two phenomena, bystander versus adaptive response, is more important has practical implication in terms of low dose radiation risk assessment. In this review, genotoxicity is used as an endpoint to introduce the two phenomena, provide some insight into the mechanisms of bystander effect and to bridge the two low dose phenomena which operate in opposite directions: the bystander effect tends to exaggerate the effect at low doses, by communicating damage from hit to non-hit cells whereas the adaptive response confers resistance to a subsequent challenging dose by an initial low priming dose.
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Affiliation(s)
- Tom K Hei
- Center for Radiological Research, College of Physicians and Surgeons, Columbia University, Vanderbilt Clinic 11-205, 630 West 168th Street, New York, NY 10032, USA.
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Ohnishi K, Ohnishi T. The Biological Effects of Space Radiation during Long Stays in Space. ACTA ACUST UNITED AC 2004; 18:201-5. [PMID: 15858386 DOI: 10.2187/bss.18.201] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Many space experiments are scheduled for the International Space Station (ISS). Completion of the ISS will soon become a reality. Astronauts will be exposed to low-level background components from space radiation including heavy ions and other high-linear energy transfer (LET) radiation. For long-term stay in space, we have to protect human health from space radiation. At the same time, we should recognize the maximum permissible doses of space radiation. In recent years, physical monitoring of space radiation has detected about 1 mSv per day. This value is almost 150 times higher than that on the surface of the Earth. However, the direct effects of space radiation on human health are currently unknown. Therefore, it is important to measure biological dosimetry to calculate relative biological effectiveness (RBE) for human health during long-term flight. The RBE is possibly modified by microgravity. In order to understand the exact RBE and any interaction with microgravity, the ISS centrifugation system will be a critical tool, and it is hoped that this system will be in operation as soon as possible.
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Affiliation(s)
- Ken Ohnishi
- Department of Biology, Nara Medical University School of Medicine, Kashihara, Nara, Japan
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