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Guéguen Y, Bontemps A, Ebrahimian TG. Adaptive responses to low doses of radiation or chemicals: their cellular and molecular mechanisms. Cell Mol Life Sci 2019; 76:1255-1273. [PMID: 30535789 PMCID: PMC11105647 DOI: 10.1007/s00018-018-2987-5] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 11/09/2018] [Accepted: 12/03/2018] [Indexed: 12/17/2022]
Abstract
This article reviews the current knowledge on the mechanisms of adaptive response to low doses of ionizing radiation or chemical exposure. A better knowledge of these mechanisms is needed to improve our understanding of health risks at low levels of environmental or occupational exposure and their involvement in cancer or non-cancer diseases. This response is orchestrated through a multifaceted cellular program involving the concerted action of diverse stress response pathways. These evolutionary highly conserved defense mechanisms determine the cellular response to chemical and physical aggression. They include DNA damage repair (p53, ATM, PARP pathways), antioxidant response (Nrf2 pathway), immune/inflammatory response (NF-κB pathway), cell survival/death pathway (apoptosis), endoplasmic response to stress (UPR response), and other cytoprotective processes including autophagy, cell cycle regulation, and the unfolded protein response. The coordinated action of these processes induced by low-dose radiation or chemicals produces biological effects that are currently estimated with the linear non-threshold model. These effects are controversial. They are difficult to detect because of their low magnitude, the scarcity of events in humans, and the difficulty of corroborating associations over the long term. Improving our understanding of these biological consequences should help humans and their environment by enabling better risk estimates, the revision of radiation protection standards, and possible therapeutic advances.
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Affiliation(s)
- Yann Guéguen
- Institut de Radioprotection et de Sureté Nucléaire (IRSN), PSE-SANTE, SESANE, LRTOX, B.P. no 17, 92262, Fontenay-aux-Roses Cedex, France.
- Institut de Radioprotection et de Sureté Nucléaire (IRSN), PSE-SANTE, SESANE, LRSI, Fontenay-aux-Roses, France.
| | - Alice Bontemps
- Institut de Radioprotection et de Sureté Nucléaire (IRSN), PSE-SANTE, SESANE, LRTOX, B.P. no 17, 92262, Fontenay-aux-Roses Cedex, France
| | - Teni G Ebrahimian
- Institut de Radioprotection et de Sureté Nucléaire (IRSN), PSE-SANTE, SESANE, LRTOX, B.P. no 17, 92262, Fontenay-aux-Roses Cedex, France
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Kong EY, Cheng SH, Yu KN. Zebrafish as an In Vivo Model to Assess Epigenetic Effects of Ionizing Radiation. Int J Mol Sci 2016; 17:ijms17122108. [PMID: 27983682 PMCID: PMC5187908 DOI: 10.3390/ijms17122108] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Revised: 12/01/2016] [Accepted: 12/09/2016] [Indexed: 12/14/2022] Open
Abstract
Exposure to ionizing radiations (IRs) is ubiquitous in our environment and can be categorized into “targeted” effects and “non-targeted” effects. In addition to inducing deoxyribonucleic acid (DNA) damage, IR exposure leads to epigenetic alterations that do not alter DNA sequence. Using an appropriate model to study the biological effects of radiation is crucial to better understand IR responses as well as to develop new strategies to alleviate exposure to IR. Zebrafish, Danio rerio, is a scientific model organism that has yielded scientific advances in several fields and recent studies show the usefulness of this vertebrate model in radiation biology. This review briefly describes both “targeted” and “non-targeted” effects, describes the findings in radiation biology using zebrafish as a model and highlights the potential of zebrafish to assess the epigenetic effects of IR, including DNA methylation, histone modifications and miRNA expression. Other in vivo models are included to compare observations made with zebrafish, or to illustrate the feasibility of in vivo models when the use of zebrafish was unavailable. Finally, tools to study epigenetic modifications in zebrafish, including changes in genome-wide DNA methylation, histone modifications and miRNA expression, are also described in this review.
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Affiliation(s)
- Eva Yi Kong
- Department of Physics and Materials Science, City University of Hong Kong, Hong Kong, China.
| | - Shuk Han Cheng
- Department of Biomedical Sciences, City University of Hong Kong, Hong Kong, China.
- State Key Laboratory in Marine Pollution, City University of Hong Kong, Hong Kong, China.
| | - Kwan Ngok Yu
- Department of Physics and Materials Science, City University of Hong Kong, Hong Kong, China.
- State Key Laboratory in Marine Pollution, City University of Hong Kong, Hong Kong, China.
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Niwa O, Barcellos-Hoff MH, Globus RK, Harrison JD, Hendry JH, Jacob P, Martin MT, Seed TM, Shay JW, Story MD, Suzuki K, Yamashita S. ICRP Publication 131: Stem Cell Biology with Respect to Carcinogenesis Aspects of Radiological Protection. Ann ICRP 2016; 44:7-357. [PMID: 26637346 DOI: 10.1177/0146645315595585] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
This report provides a review of stem cells/progenitor cells and their responses to ionising radiation in relation to issues relevant to stochastic effects of radiation that form a major part of the International Commission on Radiological Protection's system of radiological protection. Current information on stem cell characteristics, maintenance and renewal, evolution with age, location in stem cell 'niches', and radiosensitivity to acute and protracted exposures is presented in a series of substantial reviews as annexes concerning haematopoietic tissue, mammary gland, thyroid, digestive tract, lung, skin, and bone. This foundation of knowledge of stem cells is used in the main text of the report to provide a biological insight into issues such as the linear-no-threshold (LNT) model, cancer risk among tissues, dose-rate effects, and changes in the risk of radiation carcinogenesis by age at exposure and attained age. Knowledge of the biology and associated radiation biology of stem cells and progenitor cells is more developed in tissues that renew fairly rapidly, such as haematopoietic tissue, intestinal mucosa, and epidermis, although all the tissues considered here possess stem cell populations. Important features of stem cell maintenance, renewal, and response are the microenvironmental signals operating in the niche residence, for which a well-defined spatial location has been identified in some tissues. The identity of the target cell for carcinogenesis continues to point to the more primitive stem cell population that is mostly quiescent, and hence able to accumulate the protracted sequence of mutations necessary to result in malignancy. In addition, there is some potential for daughter progenitor cells to be target cells in particular cases, such as in haematopoietic tissue and in skin. Several biological processes could contribute to protecting stem cells from mutation accumulation: (a) accurate DNA repair; (b) rapidly induced death of injured stem cells; (c) retention of the DNA parental template strand during divisions in some tissue systems, so that mutations are passed to the daughter differentiating cells and not retained in the parental cell; and (d) stem cell competition, whereby undamaged stem cells outcompete damaged stem cells for residence in the niche. DNA repair mainly occurs within a few days of irradiation, while stem cell competition requires weeks or many months depending on the tissue type. The aforementioned processes may contribute to the differences in carcinogenic radiation risk values between tissues, and may help to explain why a rapidly replicating tissue such as small intestine is less prone to such risk. The processes also provide a mechanistic insight relevant to the LNT model, and the relative and absolute risk models. The radiobiological knowledge also provides a scientific insight into discussions of the dose and dose-rate effectiveness factor currently used in radiological protection guidelines. In addition, the biological information contributes potential reasons for the age-dependent sensitivity to radiation carcinogenesis, including the effects of in-utero exposure.
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Testi S, Azzarà A, Giovannini C, Lombardi S, Piaggi S, Facioni MS, Scarpato R. Vincristine-induced bystander effect in human lymphocytes. Mutat Res 2016; 789:39-47. [PMID: 27050754 DOI: 10.1016/j.mrfmmm.2016.03.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Revised: 02/11/2016] [Accepted: 03/24/2016] [Indexed: 06/05/2023]
Abstract
Bystander effect is a known radiobiological effect, widely described using ionizing radiations and which, more recently, has also been related to chemical mutagens. In this study, we aimed to assess whether or not a bystander response can be induced in cultured human peripheral lymphocytes by vincristine, a chemotherapeutic mutagen acting as spindle poison, and by mitomycin-C, an alkylating agent already known to induce this response in human lymphoblastoid cells. Designing a modified ad hoc protocol for the cytokinesis blocked micronucleus (MN) assay, we detected the presence of a dose-dependent bystander response in untreated cultures receiving the conditioned medium (CM) from mitomycin-C (MMC) or vincristine (VCR) treated cultures. In the case of MMC, MN frequencies, expressed as micronucleated binucleates, were: 13.5±1.41 at 6μM, 22±2.12 at 12μM or 28.25±5.13 at 15μM vs. a control value of 4.75±1.59. MN levels for VCR, expressed as micronucleated mononucleates were: 2.75±0.88 at 0.0μM, 27.25±2.30 at 0.4μM, 46.25±1.94 at 0.8μM, 98.25±7.25 at 1.6μM. To verify that no mutagen residual was transferred to recipient cultures together with the CM, we evaluated MN levels in cultures receiving the medium immediately after three washings following the chemical treatment (unconditioned medium). We further confirmed these results using a cell-mixing approach where untreated lymphocytes were co-cultured with donor cells treated with an effect-inducing dose of MMC or VCR. A distinct production pattern of both reactive oxygen species and soluble mediator proteins by treated cells may account for the differences observed in the manifestation of the bystander effect induced by VCR. In fact, we observed an increased level of ROS, IL-32 and TGF-β in the CM from VCR treated cultures, not present in MMC treated cultures.
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Affiliation(s)
- Serena Testi
- Unità di Genetica, Dipartimento di Biologia, Pisa University, Via Derna 1, 56126 Pisa, Italy
| | - Alessia Azzarà
- Unità di Genetica, Dipartimento di Biologia, Pisa University, Via Derna 1, 56126 Pisa, Italy
| | - Caterina Giovannini
- Unità di Genetica, Dipartimento di Biologia, Pisa University, Via Derna 1, 56126 Pisa, Italy
| | - Sara Lombardi
- Unità di Genetica, Dipartimento di Biologia, Pisa University, Via Derna 1, 56126 Pisa, Italy
| | - Simona Piaggi
- Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia, Pisa University, Via Savi 10, 56126 Pisa, Italy
| | - Maria Sole Facioni
- Unità di Genetica, Dipartimento di Biologia, Pisa University, Via Derna 1, 56126 Pisa, Italy
| | - Roberto Scarpato
- Unità di Genetica, Dipartimento di Biologia, Pisa University, Via Derna 1, 56126 Pisa, Italy; Research Center of Nutraceuticals and Food for Health, University of Pisa, Pisa, Italy.
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Xu S, Ding N, Pei H, Hu W, Wei W, Zhang X, Zhou G, Wang J. MiR-21 is involved in radiation-induced bystander effects. RNA Biol 2015; 11:1161-70. [PMID: 25483031 DOI: 10.4161/rna.34380] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Radiation-induced bystander effects are well-established phenomena, in which DNA damage responses are induced not only in the directly irradiated cells but also in the non-irradiated bystander cells through intercellular signal transmission. Recent studies hint that bystander effects are possibly mediated via small non-coding RNAs, especially microRNAs. Thus, more details about the roles of microRNA in bystander effects are urgently needed to be elucidated. Here we demonstrated that bystander effects were induced in human fetal lung MRC-5 fibroblasts through medium-mediated way by different types of radiation. We identified a set of differentially expressed microRNAs in the cell culture medium after irradiation, among which the up-regulation of miR-21 was further verified with qRT-PCR. In addition, we found significant upregulation of miR-21 in both directly irradiated cells and bystander cells, which was confirmed by the expression of miR-21 precursor and its target genes. Transfection of miR-21 mimics into non-irradiated MRC-5 cells caused bystander-like effects. Taken together, our data reveals that miR-21 is involved in radiation-induced bystander effects. Elucidation of such a miRNA-mediated bystander effect is of utmost importance in understanding the biological processes related to ionizing radiation and cell-to-cell communication.
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Affiliation(s)
- Shuai Xu
- a Department of Space Radiobiology; Key Laboratory of Heavy Ion Radiation Biology and Medicine; Institute of Modern Physics; Chinese Academy of Sciences ; Lanzhou , P.R. China
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Choi VWY, Yu KN. Embryos of the zebrafish Danio rerio in studies of non-targeted effects of ionizing radiation. Cancer Lett 2013; 356:91-104. [PMID: 24176822 DOI: 10.1016/j.canlet.2013.10.020] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Revised: 10/16/2013] [Accepted: 10/22/2013] [Indexed: 01/17/2023]
Abstract
The use of embryos of the zebrafish Danio rerio as an in vivo tumor model for studying non-targeted effects of ionizing radiation was reviewed. The zebrafish embryo is an animal model, which enables convenient studies on non-targeted effects of both high-linear-energy-transfer (LET) and low-LET radiation by making use of both broad-beam and microbeam radiation. Zebrafish is also a convenient embryo model for studying radiobiological effects of ionizing radiation on tumors. The embryonic origin of tumors has been gaining ground in the past decades, and efforts to fight cancer from the perspective of developmental biology are underway. Evidence for the involvement of radiation-induced genomic instability (RIGI) and the radiation-induced bystander effect (RIBE) in zebrafish embryos were subsequently given. The results of RIGI were obtained for the irradiation of all two-cell stage cells, as well as 1.5 hpf zebrafish embryos by microbeam protons and broad-beam alpha particles, respectively. In contrast, the RIBE was observed through the radioadaptive response (RAR), which was developed against a subsequent challenging dose that was applied at 10 hpf when <0.2% and <0.3% of the cells of 5 hpf zebrafish embryos were exposed to a priming dose, which was provided by microbeam protons and broad-beam alpha particles, respectively. Finally, a perspective on the field, the need for future studies and the significance of such studies were discussed.
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Affiliation(s)
- V W Y Choi
- Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong
| | - K N Yu
- Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong; State Key Laboratory in Marine Pollution, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong.
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Bréchignac F, Paquet F. Radiation-induced risks at low dose: moving beyond controversy towards a new vision. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2013; 52:299-301. [PMID: 23689951 DOI: 10.1007/s00411-013-0473-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Accepted: 04/27/2013] [Indexed: 06/02/2023]
Abstract
The paper recently published by Mothersill and Seymour (Radiat Environ Biophys 2013, doi: 10.1007/s00411-013-0472-y ) is commented upon by emphasizing on the recommendation not to confound the fields of radiation protection and radiobiological science as a source of controversy. Instead, these authors are proposing a new vision which suggests novel lines of scientific investigations to be addressed. At the moment, these include moving beyond the conceptual approach of DNA alteration through energy deposition in cells, and exploring the striking parallel currently existing between the ongoing individual/population debate in radioecology and that for cells/tissues in radiobiology. These interesting issues are briefly discussed and supported.
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Affiliation(s)
- François Bréchignac
- Institute for Radioprotection and Nuclear Safety-IRSN, Centre of Cadarache, BP 3, 13115, St Paul-lez-Durance Cedex, France.
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Mairs RJ, Boyd M. Preclinical assessment of strategies for enhancement of metaiodobenzylguanidine therapy of neuroendocrine tumors. Semin Nucl Med 2012; 41:334-44. [PMID: 21803183 DOI: 10.1053/j.semnuclmed.2011.03.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
By virtue of its high affinity for the norepinephrine transporter (NET), [(131)I]metaiodobenzylguanidine ([(131)I]MIBG) has been used for the therapy of tumors of neuroectodermal origin for more than 25 years. Although not yet universally adopted, [(131)I]MIBG targeted radiotherapy remains a highly promising means of management of neuroblastoma, pheochromocytoma, and carcinoids. Appreciation of the mode of conveyance of [(131)I]MIBG into malignant cells and of factors that influence the activity of the uptake mechanism has indicated a variety of means of increasing the effectiveness of this type of treatment. Studies in model systems revealed that radiolabeling of MIBG to high specific activity reduced the amount of cold competitor, thereby increasing tumor dose and minimizing pressor effects. Increased radiotoxicity to targeted tumors might also be achieved by the use of the α-particle emitter [(211)At]astatine rather than (131)I as radiolabel. Recently it has been demonstrated that potent cytotoxic bystander effects were induced by [(131)I]MIBG, [(123)I]MIBG, and [(211)At]meta-astatobenzylguanidine. Discovery of the structure of bystander factors could increase the therapeutic ratio achievable by MIBG targeted radiotherapy. [(131)I]MIBG combined with topotecan produced supra-additive cytotoxicity in vitro and tumor growth delay in vivo. The enhanced antitumor effect was consistent with a failure to repair DNA damage. Initial findings suggest that further enhancement of efficacy might be achieved by triple combination therapy with drugs that disrupt alternative tumor-specific pathways and synergize not only with [(131)I]MIBG abut also with topotecan. With these ploys, it is expected that advances will be made toward the optimization of [(131)I]MIBG therapy of neuroectodermal tumors.
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Affiliation(s)
- Rob J Mairs
- Radiation Oncology, Division of Cancer Science and Molecular Pathology, University of Glasgow, Cancer Research UK, Beatson Laboratories, Glasgow, Scotland.
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Truta-Popa LA, Hofmann W, Fakir H, Cosma C. The effect of non-targeted cellular mechanisms on lung cancer risk for chronic, low level radon exposures. Int J Radiat Biol 2011; 87:944-53. [PMID: 21770704 DOI: 10.3109/09553002.2011.584936] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE The goal of the present study was to investigate the effect of non-targeted mechanisms on the shape of the lung cancer risk function at chronic, low level radon exposures relative to direct cellular radiation effects. This includes detrimental and protective bystander effects, radio-adaptive bystander response, genomic instability and induction of apoptosis by surrounding cells. METHODS To quantify the dependence of these mechanisms on dose, analytical functions were derived from the experimental evidence presently available. Alpha particle intersections of bronchial target cells during a given exposure period were simulated by a Transformation Frequency-Tissue Response (TF-TR) model, formulated in terms of cellular hits within the cycle time of the cell and then integrated over the whole exposure period. RESULTS In general, non-targeted effects like genomic instability and bystander effects amplify the biological effectiveness of a given radiation dose, while induction of apoptosis and adaptive response will decrease the risk values. While these observations are related to the absolute number of lung cancer cases, normalization to the epidemiologically observed risk at 0.675 Gy suggests that the effect of such mechanisms on the shape of the dose-response relationship may be different. Indeed, genomic instability and adaptive response cause a substantial reduction of the risk at low doses, while induction of apoptosis and detrimental bystander effects slightly increase the risk. CONCLUSIONS Predictions of lung cancer risk, including these mechanisms, exhibit a distinct sublinear dose-response relationship at low exposures, particularly for very low exposure rates. However, the relatively large error bars of the epidemiological data do not currently allow the prediction of a statistically significant deviation from the Linear - No Threshold (LNT) assumption.
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Affiliation(s)
- Lucia A Truta-Popa
- Faculty of Environmental Sciences and Engineering, Babes-Bolyai University, Cluj-Napoca, Romania.
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Blyth BJ, Azzam EI, Howell RW, Ormsby RJ, Staudacher AH, Sykes PJ. An adoptive transfer method to detect low-dose radiation-induced bystander effects in vivo. Radiat Res 2010; 173:125-37. [PMID: 20095844 DOI: 10.1667/rr1899.1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The potential for irradiated cells to induce biological effects in their unirradiated neighbors (known as the bystander effect) has been observed repeatedly in vitro. However, whether bystander effects occur in vivo under the specific conditions relevant to low-dose radiation protection is still unclear. To test this, the fate of bystander cells in the mouse spleen was examined using an adoptive transfer method designed to replicate the rare, irradiated cells in an organ that might be expected after a low-dose-rate, low-LET radiation exposure. Splenic lymphocytes radiolabeled with low activities of (3)H-thymidine were introduced into the spleens of unirradiated recipient mice. In this study, the apoptotic and proliferative response of the neighboring bystander spleen cells was compared to the response of spleen cells in parallel control recipients that received sham-irradiated cells. Neither the local area surrounding lodged radiolabeled cells nor the spleen as a whole showed a change in apoptosis or proliferation either 1 or 3 days after adoptive transfer. Increasing the irradiated cell numbers, increasing the mean (3)H-thymidine activity per cell, or exposing cells ex vivo to an acute X-ray dose also had no effect. Possible reasons for the absence of a bystander effect in the spleen under these conditions are discussed.
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Affiliation(s)
- Benjamin J Blyth
- a Haematology and Genetic Pathology, Flinders University, Bedford Park, South Australia 5042, Australia
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Boyd M, Sorensen A, McCluskey AG, Mairs RJ. Radiation quality-dependent bystander effects elicited by targeted radionuclides. J Pharm Pharmacol 2008; 60:951-8. [PMID: 18644188 DOI: 10.1211/jpp.60.8.0002] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
The efficacy of radiotherapy may be partly dependent on indirect effects, which can sterilise malignant cells that are not directly irradiated. However, little is known of the influence of these effects in targeted radionuclide treatment of cancer. We determined bystander responses generated by the uptake of radioiodinated iododeoxyuridine ([*I]IUdR) and radiohaloanalogues of meta-iodobenzylguanidine ([*I]MIBG) by noradrenaline transporter (NAT) gene-transfected tumour cells. NAT specifically accumulates MIBG. Multicellular spheroids that consisted of 5% of NAT-expressing cells, capable of the active uptake of radiopharmaceutical, were sterilised by treatment with 20 kBqmL(-1) of the alpha-emitter meta-[211At]astatobenzylguanidine ([211At]MABG). Similarly, in nude mice, retardation of the growth of tumour xenografts containing 5% NAT-positivity was observed after treatment with [131I]MIBG. To determine the effect of subcellular localisation of radiolabelled drugs, we compared the bystander effects resulting from the intracellular concentration of [131I]MIBG and [131I]IUdR (low linear energy transfer (LET) beta-emitters) as well as [123I]MIBG and [123I]IUdR (high LET Auger electron emitters). [*I]IUdR is incorporated in DNA whereas [*I]MIBG accumulates in extranuclear sites. Cells exposed to media from [131I]MIBG- or [131I]IUdR-treated cells demonstrated a dose-response relationship with respect to clonogenic cell death. In contrast, cells receiving media from cultures treated with [123I]MIBG or [123I]IUdR exhibited dose-dependent toxicity at low dose but elimination of cytotoxicity with increasing radiation dose (i.e. U-shaped survival curves). Therefore radionuclides emitting high LET radiation may elicit toxic or protective effects on neighbouring untargeted cells at low and high dose respectively. It is concluded that radiopharmaceutical-induced bystander effects may depend on LET of the decay particles but are independent of site of intracellular concentration of radionuclide.
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Affiliation(s)
- Marie Boyd
- Targeted Therapy Group, Division of Cancer Sciences, Faculty of Medicine, Glasgow University, Cancer Research UK Beatson Laboratories, Glasgow, G61 1BD, UK
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Optimizing MIBG therapy of neuroendocrine tumors: preclinical evidence of dose maximization and synergy. Nucl Med Biol 2008; 35 Suppl 1:S9-20. [DOI: 10.1016/j.nucmedbio.2008.04.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2008] [Revised: 04/09/2008] [Accepted: 04/23/2008] [Indexed: 11/19/2022]
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Matsumoto H, Hamada N, Takahashi A, Kobayashi Y, Ohnishi T. Vanguards of paradigm shift in radiation biology: radiation-induced adaptive and bystander responses. JOURNAL OF RADIATION RESEARCH 2007; 48:97-106. [PMID: 17327685 DOI: 10.1269/jrr.06090] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
The risks of exposure to low dose ionizing radiation (below 100 mSv) are estimated by extrapolating from data obtained after exposure to high dose radiation, using a linear no-threshold model (LNT model). However, the validity of using this dose-response model is controversial because evidence accumulated over the past decade has indicated that living organisms, including humans, respond differently to low dose/low dose-rate radiation than they do to high dose/high dose-rate radiation. In other words, there are accumulated findings which cannot be explained by the classical "target theory" of radiation biology. The radioadaptive response, radiation-induced bystander effects, low-dose radio-hypersensitivity, and genomic instability are specifically observed in response to low dose/low dose-rate radiation, and the mechanisms underlying these responses often involve biochemical/molecular signals that respond to targeted and non-targeted events. Recently, correlations between the radioadaptive and bystander responses have been increasingly reported. The present review focuses on the latter two phenomena by summarizing observations supporting their existence, and discussing the linkage between them from the aspect of production of reactive oxygen and nitrogen species.
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Affiliation(s)
- Hideki Matsumoto
- Division of Oncology, Biomedical Imaging Research Center, University of Fukui, Eiheiji, Japan.
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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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Matsumoto H, Takahashi A, Ohnishi T. Radiation-induced adaptive responses and bystander effects. ACTA ACUST UNITED AC 2005; 18:247-54. [PMID: 15858392 DOI: 10.2187/bss.18.247] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
A classical paradigm [correction of paradym] of radiation biology asserts that all radiation effects on cells, tissues and organisms are due to the direct action of radiation. However, there has been a recent growth of interest in the indirect actions of radiation including the radiation-induced adaptive response, the bystander effect, low-dose hypersensitivity, and genomic instability, which are specific modes of stress exhibited in response to low-dose/low-dose rate radiation. This review focuses on the radiation-induced bystander effect and the adaptive response, provides a description of the two phenomena, and discusses the contribution of the former to the latter.
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Affiliation(s)
- Hideki Matsumoto
- Department of Experimental Radiology and Health Physics, Faculty of Medical Science, University of Fukui, Matsuoka, Fukui, Japan.
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