1
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Deng Y, Peng X, Gerweck LE. Acute Large Dose Irradiation Sensitizes Surviving Cells to Subsequent Irradiation; Implications for Stereotactic Body Radiation Therapy. Radiat Res 2024; 201:261-266. [PMID: 38198248 DOI: 10.1667/rade-22-00166.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Accepted: 12/20/2023] [Indexed: 01/12/2024]
Abstract
To determine if the radiation sensitivity of cells that survive acute high-dose radiation exposure used in stereotactic body radiation therapy (SBRT), differs from the sensitivity of non-irradiated cells and cells that survive multiple 2 Gy doses of radiation. Isogenic rodent and two human tumor cell lines were exposed to 14 × 2 Gy of radiation, or a single acute dose of 12 Gy. The most resistant cell line was also exposed to an acute dose of 15 Gy. One week after 12 Gy, and 4 days after 14 × 2 Gy, surviving cells were exposed to 0-8 Gy in 2 Gy doses and cell survival was assessed by colony formation. In addition, the colony forming efficiency of 12 Gy survivors was evaluated for 1 month postirradiation. For cells exposed to 15 Gy, the response of surviving cells to 6 Gy was determined for up to 35 days postirradiation and compared to the 6 Gy surviving fraction of control cells. The radiation sensitivity of cells that survived 12 Gy exposure, and cells that survived 14 fractions of 2 Gy irradiation did not differ from the response of unirradiated control cells. However, the growth rate and colony forming efficiency of 12 Gy survivors was transiently reduced for greater than 2 weeks postirradiation. In contrast to the unchanged sensitivity of 12 Gy surviving cells at day 7 postirradiation, 15 Gy survivors exhibited enhanced sensitivity to radiation for up to 21 days postirradiation and suggests a biological basis for SBRT.
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Affiliation(s)
- Yaotiao Deng
- Department of Radiation Oncology, Massachusetts General Hospital, Boston Massachusetts 02144
| | - Xingchen Peng
- Department of Radiation Oncology, Massachusetts General Hospital, Boston Massachusetts 02144
| | - Leo E Gerweck
- Department of Radiation Oncology, Massachusetts General Hospital, Boston Massachusetts 02144
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2
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Averbeck D. Low-Dose Non-Targeted Effects and Mitochondrial Control. Int J Mol Sci 2023; 24:11460. [PMID: 37511215 PMCID: PMC10380638 DOI: 10.3390/ijms241411460] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 06/26/2023] [Accepted: 06/29/2023] [Indexed: 07/30/2023] Open
Abstract
Non-targeted effects (NTE) have been generally regarded as a low-dose ionizing radiation (IR) phenomenon. Recently, regarding long distant abscopal effects have also been observed at high doses of IR) relevant to antitumor radiation therapy. IR is inducing NTE involving intracellular and extracellular signaling, which may lead to short-ranging bystander effects and distant long-ranging extracellular signaling abscopal effects. Internal and "spontaneous" cellular stress is mostly due to metabolic oxidative stress involving mitochondrial energy production (ATP) through oxidative phosphorylation and/or anaerobic pathways accompanied by the leakage of O2- and other radicals from mitochondria during normal or increased cellular energy requirements or to mitochondrial dysfunction. Among external stressors, ionizing radiation (IR) has been shown to very rapidly perturb mitochondrial functions, leading to increased energy supply demands and to ROS/NOS production. Depending on the dose, this affects all types of cell constituents, including DNA, RNA, amino acids, proteins, and membranes, perturbing normal inner cell organization and function, and forcing cells to reorganize the intracellular metabolism and the network of organelles. The reorganization implies intracellular cytoplasmic-nuclear shuttling of important proteins, activation of autophagy, and mitophagy, as well as induction of cell cycle arrest, DNA repair, apoptosis, and senescence. It also includes reprogramming of mitochondrial metabolism as well as genetic and epigenetic control of the expression of genes and proteins in order to ensure cell and tissue survival. At low doses of IR, directly irradiated cells may already exert non-targeted effects (NTE) involving the release of molecular mediators, such as radicals, cytokines, DNA fragments, small RNAs, and proteins (sometimes in the form of extracellular vehicles or exosomes), which can induce damage of unirradiated neighboring bystander or distant (abscopal) cells as well as immune responses. Such non-targeted effects (NTE) are contributing to low-dose phenomena, such as hormesis, adaptive responses, low-dose hypersensitivity, and genomic instability, and they are also promoting suppression and/or activation of immune cells. All of these are parts of the main defense systems of cells and tissues, including IR-induced innate and adaptive immune responses. The present review is focused on the prominent role of mitochondria in these processes, which are determinants of cell survival and anti-tumor RT.
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Affiliation(s)
- Dietrich Averbeck
- Laboratory of Cellular and Molecular Radiobiology, PRISME, UMR CNRS 5822/IN2P3, IP2I, Lyon-Sud Medical School, University Lyon 1, 69921 Oullins, France
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3
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López-Nieva P, González-Vasconcellos I, González-Sánchez L, Cobos-Fernández MA, Ruiz-García S, Sánchez Pérez R, Aroca Á, Fernández-Piqueras J, Santos J. Differential molecular response in mice and human thymocytes exposed to a combined-dose radiation regime. Sci Rep 2022; 12:3144. [PMID: 35210498 PMCID: PMC8873405 DOI: 10.1038/s41598-022-07166-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 02/11/2022] [Indexed: 11/17/2022] Open
Abstract
In the quest for more effective radiation treatment options that can improve both cell killing and healthy tissue recovery, combined radiation therapies are lately in the spotlight. The molecular response to a combined radiation regime where exposure to an initial low dose (priming dose) of ionizing radiation is administered prior to a subsequent higher radiation dose (challenging dose) after a given latency period have not been thoroughly explored. In this study we report on the differential response to either a combined radiation regime or a single challenging dose both in mouse in vivo and in human ex vivo thymocytes. A differential cell cycle response including an increase in the subG1 fraction on cells exposed to the combined regime was found. Together with this, a differential protein expression profiling in several pathways including cell cycle control (ATM, TP53, p21CDKN1A), damage response (γH2AX) and cell death pathways such as apoptosis (Cleaved Caspase-3, PARP1, PKCδ and H3T45ph) and ferroptosis (xCT/GPX4) was demonstrated. This study also shows the epigenetic regulation following a combined regime that alters the expression of chromatin modifiers such as DNMTs (DNMT1, DNMT2, DNMT3A, DNMT3B, DNMT3L) and glycosylases (MBD4 and TDG). Furthermore, a study of the underlying cellular status six hours after the priming dose alone showed evidence of retained modifications on the molecular and epigenetic pathways suggesting that the priming dose infers a “radiation awareness phenotype” to the thymocytes, a sensitization key to the differential response seen after the second hit with the challenging dose. These data suggest that combined-dose radiation regimes could be more efficient at making cells respond to radiation and it would be interesting to further investigate how can these schemes be of use to potential new radiation therapies.
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Affiliation(s)
- Pilar López-Nieva
- Genome Dynamics and Function Program, Genome Decoding Unit, Severo Ochoa Molecular Biology Center, Madrid, Spain. .,Department of Biology, Madrid Autonomous University, 28049, Madrid, Spain. .,Institute of Health Research, Jiménez Díaz Foundation, 28040, Madrid, Spain.
| | - Iria González-Vasconcellos
- Genome Dynamics and Function Program, Genome Decoding Unit, Severo Ochoa Molecular Biology Center, Madrid, Spain. .,Department of Biology, Madrid Autonomous University, 28049, Madrid, Spain.
| | - Laura González-Sánchez
- Genome Dynamics and Function Program, Genome Decoding Unit, Severo Ochoa Molecular Biology Center, Madrid, Spain.,Institute of Health Research, Jiménez Díaz Foundation, 28040, Madrid, Spain.,Consorcio de Investigación Biomédica de Enfermedades Raras (CIBERER), Madrid, Spain
| | - María A Cobos-Fernández
- Genome Dynamics and Function Program, Genome Decoding Unit, Severo Ochoa Molecular Biology Center, Madrid, Spain.,Department of Biology, Madrid Autonomous University, 28049, Madrid, Spain
| | - Sara Ruiz-García
- Genome Dynamics and Function Program, Genome Decoding Unit, Severo Ochoa Molecular Biology Center, Madrid, Spain.,Department of Biology, Madrid Autonomous University, 28049, Madrid, Spain
| | - Raúl Sánchez Pérez
- Department of Congenital Cardiac Surgery, Hospital Universitario La Paz, 28046, Madrid, Spain
| | - Ángel Aroca
- Department of Congenital Cardiac Surgery, Hospital Universitario La Paz, 28046, Madrid, Spain
| | - José Fernández-Piqueras
- Genome Dynamics and Function Program, Genome Decoding Unit, Severo Ochoa Molecular Biology Center, Madrid, Spain.,Department of Biology, Madrid Autonomous University, 28049, Madrid, Spain.,Institute of Health Research, Jiménez Díaz Foundation, 28040, Madrid, Spain
| | - Javier Santos
- Genome Dynamics and Function Program, Genome Decoding Unit, Severo Ochoa Molecular Biology Center, Madrid, Spain.,Department of Biology, Madrid Autonomous University, 28049, Madrid, Spain.,Institute of Health Research, Jiménez Díaz Foundation, 28040, Madrid, Spain
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4
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Khan MGM, Wang Y. Advances in the Current Understanding of How Low-Dose Radiation Affects the Cell Cycle. Cells 2022; 11:cells11030356. [PMID: 35159169 PMCID: PMC8834401 DOI: 10.3390/cells11030356] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 01/15/2022] [Accepted: 01/20/2022] [Indexed: 12/12/2022] Open
Abstract
Cells exposed to ionizing radiation undergo a series of complex responses, including DNA damage, reproductive cell death, and altered proliferation states, which are all linked to cell cycle dynamics. For many years, a great deal of research has been conducted on cell cycle checkpoints and their regulators in mammalian cells in response to high-dose exposures to ionizing radiation. However, it is unclear how low-dose ionizing radiation (LDIR) regulates the cell cycle progression. A growing body of evidence demonstrates that LDIR may have profound effects on cellular functions. In this review, we summarize the current understanding of how LDIR (of up to 200 mGy) regulates the cell cycle and cell-cycle-associated proteins in various cellular settings. In light of current findings, we also illustrate the conceptual function and possible dichotomous role of p21Waf1, a transcriptional target of p53, in response to LDIR.
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Affiliation(s)
- Md Gulam Musawwir Khan
- Radiobiology and Health, Canadian Nuclear Laboratories (CNL), Chalk River, ON K0J 1J0, Canada;
| | - Yi Wang
- Radiobiology and Health, Canadian Nuclear Laboratories (CNL), Chalk River, ON K0J 1J0, Canada;
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- Correspondence:
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5
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Low Dose Ionising Radiation-Induced Hormesis: Therapeutic Implications to Human Health. APPLIED SCIENCES-BASEL 2021. [DOI: 10.3390/app11198909] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The concept of radiation-induced hormesis, whereby a low dose is beneficial and a high dose is detrimental, has been gaining attention in the fields of molecular biology, environmental toxicology and radiation biology. There is a growing body of literature that recognises the importance of hormetic dose response not only in the radiation field, but also with molecular agents. However, there is continuing debate on the magnitude and mechanism of radiation hormetic dose response, which could make further contributions, as a research tool, to science and perhaps eventually to public health due to potential therapeutic benefits for society. The biological phenomena of low dose ionising radiation (LDIR) includes bystander effects, adaptive response, hypersensitivity, radioresistance and genomic instability. In this review, the beneficial and the detrimental effects of LDIR-induced hormesis are explored, together with an overview of its underlying cellular and molecular mechanisms that may potentially provide an insight to the therapeutic implications to human health in the future.
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6
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Wang B, Tanaka K, Katsube T, Maruyama K, Ninomiya Y, Varès G, Liu C, Hirakawa H, Murakami M, Fardous Z, Sultana N, Fujita K, Fujimori A, Nakajima T, Nenoi M. Reduced High-Dose Radiation-Induced Residual Genotoxic Damage by Induction of Radioadaptive Response and Prophylactic Mild Dietary Restriction in Mice. Dose Response 2021; 19:1559325820982166. [PMID: 33628149 PMCID: PMC7883164 DOI: 10.1177/1559325820982166] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 11/19/2020] [Accepted: 11/26/2020] [Indexed: 12/12/2022] Open
Abstract
Radioadaptive response (RAR) describes a phenomenon in a variety of in vitro and in vivo systems that a low-dose of priming ionizing radiation (IR) reduces detrimental effects of a subsequent challenge IR at higher doses. Among in vivo investigations, studies using the mouse RAR model (Yonezawa Effect) showed that RAR could significantly extenuate high-dose IR-induced detrimental effects such as decrease of hematopoietic stem cells and progenitor cells, acute radiation hematopoietic syndrome, genotoxicity and genomic instability. Meanwhile, it has been demonstrated that diet intervention has a great impact on health, and dietary restriction shows beneficial effects on numerous diseases in animal models. In this work, by using the mouse RAR model and mild dietary restriction (MDR), we confirmed that combination of RAR and MDR could more efficiently reduce radiogenotoxic damage without significant change of the RAR phenotype. These findings suggested that MDR may share some common pathways with RAR to activate mechanisms consequently resulting in suppression of genotoxicity. As MDR could also increase resistance to chemotherapy and radiotherapy in normal cells, we propose that combination of MDR, RAR, and other cancer treatments (i.e., chemotherapy and radiotherapy) represent a potential strategy to increase the treatment efficacy and prevent IR risk in humans.
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Affiliation(s)
- Bing Wang
- National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
| | - Kaoru Tanaka
- National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
| | - Takanori Katsube
- National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
| | - Kouichi Maruyama
- National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
| | - Yasuharu Ninomiya
- National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
| | - Guillaume Varès
- Cell Signal Unit, Okinawa Institute of Science and Technology, Okinawa, Japan
| | - Cuihua Liu
- National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
| | - Hirokazu Hirakawa
- National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
| | - Masahiro Murakami
- National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
| | - Zeenath Fardous
- Atomic Energy Research Establishment, Bangladesh Atomic Energy Commission, Dhaka, People's Republic of Bangladesh
| | - Nahida Sultana
- Atomic Energy Research Establishment, Bangladesh Atomic Energy Commission, Dhaka, People's Republic of Bangladesh
| | - Kazuko Fujita
- Department of Pathology, School of Medicine, Toho University, Tokyo, Japan
| | - Akira Fujimori
- National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
| | - Tetsuo Nakajima
- National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
| | - Mitsuru Nenoi
- Department of Safety Administration, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
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7
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Nead KT, Mitra N, Weathers B, Pyle L, Emechebe N, Pucci DA, Jacobs LA, Vaughn DJ, Nathanson KL, Kanetsky PA. Lower abdominal and pelvic radiation and testicular germ cell tumor risk. PLoS One 2020; 15:e0239321. [PMID: 33175879 PMCID: PMC7657535 DOI: 10.1371/journal.pone.0239321] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 09/04/2020] [Indexed: 11/18/2022] Open
Abstract
Background Testicular germ cell tumor (TGCT) incidence has increased in recent decades along with the use and dose of diagnostic radiation. Here we examine the association between reported exposure to diagnostic radiation and TGCT risk. Methods We conducted a case-control study of men with and without TGCT recruited from hospital- and population-based settings. Participants reported on exposures to 1) x-ray or CT below the waist and 2) lower GI series or barium enema, which consists of a series of x-rays of the colon. We also derived a combined measure of exposure. We used logistic regression to determine the risk of developing TGCT according to categories of exposures (0, 1–2, or ≥3 exposures) and age at first exposure, adjusting for age, year of birth, race, county, body mass index at diagnosis, family history of TGCT, and personal history of cryptorchidism. Results There were 315 men with TGCT and 931 men without TGCT in our study. Compared to no exposures, risk of TGCT was significantly elevated among those reporting at least three exposures to x-ray or CT (OR≥3 exposures, 1.78; 95% CI, 1.15–2.76; p = 0.010), lower GI series or barium enema (OR≥3 exposures, 4.58; 95% CI, 2.39–8.76; p<0.001), and the combined exposure variable (OR≥3 exposures, 1.59; 95% CI, 1.05–2.42; p = 0.029). The risk of TGCT was elevated for those exposed to diagnostic radiation at age 0–10 years, compared to those first exposed at age 18 years or later, although this association did not reach statistical significance (OR, 2.00; 95% CI, 0.91–4.42; p = 0.086). Conclusions Exposure to diagnostic radiation below the waist may increase TGCT risk. If these results are validated, efforts to reduce diagnostic radiation doses to the testes should be prioritized.
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Affiliation(s)
- Kevin T. Nead
- Department of Radiation Oncology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Department of Epidemiology, Department of Radiation Oncology, MD Anderson Cancer Center, Houston, Texas, United States of America
| | - Nandita Mitra
- Department of Biostatistics, Epidemiology and Informatics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Benita Weathers
- Division of Translational Medicine and Human Genetics, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Louisa Pyle
- Division of Translational Medicine and Human Genetics, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Division of Human Genetics and Metabolism, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
| | - Nnadozie Emechebe
- Department of Cancer Epidemiology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida, United States of America
- Department of Epidemiology and Biostatistics, College of Public Health, University of South Florida, Tampa, Florida, United States of America
| | - Donna A. Pucci
- Division of Hematology-Oncology, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Linda A. Jacobs
- Division of Hematology-Oncology, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Abramson Cancer Center, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - David J. Vaughn
- Division of Hematology-Oncology, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Abramson Cancer Center, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Katherine L. Nathanson
- Division of Translational Medicine and Human Genetics, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Abramson Cancer Center, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail:
| | - Peter A. Kanetsky
- Department of Cancer Epidemiology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida, United States of America
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Msaad Guerfali M, Chevrier C. Determinant factors for sperm transfer and sperm storage within Ceratitis capitata (Diptera: Tephritidae) and impact on Sterile Insect Technique. JOURNAL OF RADIATION RESEARCH AND APPLIED SCIENCES 2020. [DOI: 10.1080/16878507.2020.1855901] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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9
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Wang Z, Sugie C, Nakashima M, Kondo T, Iwata H, Tsuchiya T, Shibamoto Y. Changes in the Proliferation Rate, Clonogenicity, and Radiosensitivity of Cultured Cells During and After Continuous Low-Dose-Rate Irradiation. Dose Response 2019; 17:1559325819842733. [PMID: 31040760 PMCID: PMC6477768 DOI: 10.1177/1559325819842733] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 03/04/2019] [Accepted: 03/17/2019] [Indexed: 01/28/2023] Open
Abstract
We investigated the effects of continuous low-dose radiation on proliferation,
clonogenicity, radiosensitivity, and repair of DNA double-strand breaks (DSBs)
in human salivary gland (HSG) tumor cells. Human salivary gland cells were
cultured on acrylic boards above very-low-dose (4.3 μSv/h) or low-dose (27
μSv/h) radiation-emitting sheets or without sheets. Total cell numbers and
plating efficiencies were compared among the 3 groups every 1 or 2 weeks until 6
weeks after starting culture. At 2, 4, and 6 weeks, surviving fractions of HSG
cells after irradiation at 2 to 8 Gy cultured on the very-low-dose or low-dose
sheets were compared to those of the control. At 4 weeks, HSG cells irradiated
at 2 Gy were assessed for phosphorylated histone (γH2AX) foci formation, and
DSBs were evaluated. No significant differences were observed in total cell
number or plating efficiencies with or without low-dose-emitting sheets. The
surviving fractions after irradiation of the very-low-dose group at 2 to 6 weeks
and those of the low-dose group at 2 to 4 weeks were higher than those of the
control (P < .01). Thus, a radioadaptive response was
clearly demonstrated. From the γH2AX foci quantification, the adaptive responses
were considered to be associated with the efficient repair of DSB, especially
slow repair, in this cell line.
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Affiliation(s)
- Zhen Wang
- Department of Radiology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Chikao Sugie
- Department of Radiology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Masahiro Nakashima
- Department of Radiology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Takuhito Kondo
- Department of Radiology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Hiromitsu Iwata
- Department of Radiation Oncology, Nagoya Proton Therapy Center, Nagoya City West Medical Center, Nagoya, Japan
| | | | - Yuta Shibamoto
- Department of Radiology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
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10
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Liu C, Hirakawa H, Tanaka K, Mohd Saaya F, Nenoi M, Fujimori A, Wang B. Reduction of Delayed Homologous Recombination by Induction of Radioadaptive Response in RaDR-GFP Mice (Yonezawa Effect): An Old Player With a New Role. Dose Response 2019; 17:1559325819833840. [PMID: 30858771 PMCID: PMC6402064 DOI: 10.1177/1559325819833840] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2018] [Revised: 01/14/2019] [Accepted: 01/29/2019] [Indexed: 11/16/2022] Open
Abstract
Radiotherapy (RT) treats cancer effectively with high doses of ionizing radiation (IR) to killing cancer cells and shrinking tumors while bearing the risk of developing different side effects, including secondary cancer, which is most concerning for long-term health consequences. Genomic instability (GI) is a characteristic of most cancer cells, and IR-induced GI can manifest as delayed homologous recombination (HR). Radioadaptive response (RAR) is capable of reducing genotoxicity, cell transformation, mutation, and carcinogenesis, but the rational evidence describing its contributions to the reduction of radiation risk, in particular, carcinogenesis, remains fragmented. In this work, to investigate the impact of RAR on high-dose, IR-induced GI measured as delayed HR, the frequency of recombinant cells was comparatively studied under RAR-inducible and -uninducible conditions in the nucleated cells in hematopoietic tissues (bone marrow and spleen) using the Rosa26 Direct Repeat-green fluorescent protein (RaDR-GFP) homozygote mice. Results demonstrated that the frequency of recombinant cells was significantly lower in hematopoietic tissues under RAR-inducible condition. These findings suggest that reduction in delayed HR may be at least a part of the mechanisms underlying decreased carcinogenesis by RAR, and application of RAR would contribute to a more rigorous and scientifically grounded system of radiation protection in RT.
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Affiliation(s)
- Cuihua Liu
- National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
| | - Hirokazu Hirakawa
- National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
| | - Kaoru Tanaka
- National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
| | | | - Mitsuru Nenoi
- National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
| | - Akira Fujimori
- National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
| | - Bing Wang
- National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
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11
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Wang B, Tanaka K, Ninomiya Y, Maruyama K, Varès G, Katsube T, Murakami M, Liu C, Fujimori A, Fujita K, Liu Q, Eguchi-Kasai K, Nenoi M. Increased Hematopoietic Stem Cells/Hematopoietic Progenitor Cells Measured as Endogenous Spleen Colonies in Radiation-Induced Adaptive Response in Mice (Yonezawa Effect). Dose Response 2018; 16:1559325818790152. [PMID: 30150909 PMCID: PMC6104214 DOI: 10.1177/1559325818790152] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 06/01/2018] [Accepted: 06/12/2018] [Indexed: 12/03/2022] Open
Abstract
The existence of radiation-induced adaptive response (AR) was reported in varied
biosystems. In mice, the first in vivo AR model was established using X-rays as
both the priming and the challenge doses and rescue of bone marrow death as the
end point. The underlying mechanism was due to the priming radiation-induced
resistance in the blood-forming tissues. In a series of investigations, we
further demonstrated the existence of AR using different types of ionizing
radiation (IR) including low linear energy transfer (LET) X-rays and high LET
heavy ion. In this article, we validated hematopoietic stem cells/hematopoietic
progenitor cells (HSCs/HPCs) measured as endogenous colony-forming units-spleen
(CFU-S) under AR inducible and uninducible conditions using combination of
different types of IR. We confirmed the consistency of increased CFU-S number
change with the AR inducible condition. These findings suggest that AR in mice
induced by different types of IR would share at least in part a common
underlying mechanism, the priming IR-induced resistance in the blood-forming
tissues, which would lead to a protective effect on the HSCs/HPCs and play an
important role in rescuing the animals from bone marrow death. These findings
provide a new insight into the mechanistic study on AR in vivo.
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Affiliation(s)
- Bing Wang
- National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
| | - Kaoru Tanaka
- National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
| | - Yasuharu Ninomiya
- National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
| | - Kouichi Maruyama
- National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
| | | | - Takanori Katsube
- National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
| | - Masahiro Murakami
- National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
| | - Cuihua Liu
- National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
| | - Akira Fujimori
- National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
| | | | - Qiang Liu
- Institute of Radiation Medicine, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin, People's Republic of China
| | - Kiyomi Eguchi-Kasai
- National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
| | - Mitsuru Nenoi
- National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
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12
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Lemon JA, Phan N, Boreham DR. Single CT Scan Prolongs Survival by Extending Cancer Latency inTrp53Heterozygous Mice. Radiat Res 2017; 188:505-511. [DOI: 10.1667/rr14576.1] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Jennifer A. Lemon
- Medical Sciences Division, Northern Ontario School of Medicine, Sudbury, Canada, P3E 2C6
| | - Nghi Phan
- Department of Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, Canada, L8S 4K1
| | - Douglas R. Boreham
- Medical Sciences Division, Northern Ontario School of Medicine, Sudbury, Canada, P3E 2C6
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13
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Efficient repair of DNA double strand breaks in individuals from high level natural radiation areas of Kerala coast, south-west India. Mutat Res 2017; 806:39-50. [PMID: 28963924 DOI: 10.1016/j.mrfmmm.2017.09.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2016] [Revised: 08/14/2017] [Accepted: 09/11/2017] [Indexed: 11/21/2022]
Abstract
High level natural radiation areas (HLNRA) of Kerala coastal strip (55km long and 0.5km wide) in southwest India exhibit wide variations in the level of background dose (< 1.0-45.0mGy/year) due to thorium deposits in the beach sand. The areas with ≤1.5mGy/year are considered as normal level natural radiation area (NLNRA), whereas areas with >1.5mGy/year are HLNRA. Individuals belonging to HLNRA were stratified into two groups, Low dose group (LDG: 1.51-5.0mGy/year) and high dose group (HDG: >5.0mGy/year). The mean annual dose received by the individuals from NLNRA, LDG and HDG was 1.3±0.1, 2.7±0.9 and 9.4±2.3mGy/year, respectively. Induction and repair of DNA double strand breaks (DSBs) in terms of gamma-H2AX positive cells were analysed in peripheral blood mononuclear cells (PBMCs) using flow cytometry. Induction of DSBs was studied at low (0.25Gy) and high challenge doses (1.0 and 2.0Gy) of gamma radiation in 78 individuals {NLNRA, N=23; HLNRA (LDG, N=21 and HDG, N=34)}. Repair kinetics of DSBs were evaluated in PBMCs of 30 individuals belonging to NLNRA (N=8), LDG (N=7) and HDG (N=15) at low (0.25Gy) and high doses (2.0Gy) of gamma radiation. Transcription profile of DNA damage response (DDR) and DSB repair genes involved in non-homologous end joining (NHEJ) and homologous recombination repair (HRR) pathways was analysed after a challenge dose of 2.0Gy in PBMCs of NLNRA (N=10) and HDG, HLNRA (N=10) group. Our results revealed significantly lower induction and efficient repair of DSBs in HLNRA groups as compared to NLNRA. Transcription profile of DCLRE1C, XRCC4, NBS1 and CDK2 showed significant up-regulation (p≤0.05) in HDG at a challenge dose of 2.0Gy indicating active involvement of DDR and DSB repair pathways. In conclusion, lower induction and efficient repair of DNA DSBs in HLNRA groups is suggestive of an in vivo radio-adaptive response due to priming effect of chronic low dose radiation prevailing in this area.
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Kheirallah D, El-Samad L, Fahmi N, Osman W. Ultrastructure alterations induced by gamma irradiation in spermiogenesis of the ground beetle, Blaps sulcata: reference to environmental radiation protection. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2017; 24:22102-22110. [PMID: 28791602 DOI: 10.1007/s11356-017-9869-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 07/31/2017] [Indexed: 06/07/2023]
Abstract
Ultrastructure alterations in spermiogenesis of the ground beetle, Blaps sulcata (Coleoptera: Tenebrionidae) were studied in normal adult males and in two male groups irradiated by gamma rays of 3 and 16 μSv/h dose rate. Ultrastructure examination of irradiated sperms revealed many alterations both in the head and in the flagellum regions of mature sperm. Alterations of the head region included nuclei with uncondensed chromatin materials and irregular nuclear envelope. Abnormal flagella contained malformed mitochondrial derivatives and damaged axonemes in addition to the absence of accessory bodies. Bi- and multi-flagellate sperms (with two, three, and four axonemes) were the most common alterations. Sperm cells with residual bodies were also obtained. Agglutinated sperms and sperms with enlarged and/or vacuolated cytoplasm were common. Sperm abnormalities were more pronounced in males irradiated by 16 μSv/h dose rate than those irradiated by 3 μSv/h. Spermiogenesis alterations induced by irradiation of B. sulcata may be used as a monitoring model for predicting the effects of environmental radioactivity.
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Affiliation(s)
- Dalia Kheirallah
- Department of Zoology, Faculty of Science, Alexandria University, Alexandria, 21568, Egypt
| | - Lamia El-Samad
- Department of Zoology, Faculty of Science, Alexandria University, Alexandria, 21568, Egypt
| | - Naglaa Fahmi
- Department of Physics, Faculty of Science, Alexandria University, Alexandria, 21568, Egypt
| | - Wafaa Osman
- Department of Zoology, Faculty of Science, Alexandria University, Alexandria, 21568, Egypt.
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15
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Alessio N, Esposito G, Galano G, De Rosa R, Anello P, Peluso G, Tabocchini MA, Galderisi U. Irradiation of Mesenchymal Stromal Cells With Low and High Doses of Alpha Particles Induces Senescence and/or Apoptosis. J Cell Biochem 2017; 118:2993-3002. [PMID: 28252222 DOI: 10.1002/jcb.25961] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 02/28/2017] [Indexed: 12/25/2022]
Abstract
The use of high-linear energy transfer charged particles is gaining attention as a medical tool because of the emission of radiations with an efficient cell-killing ability. Considerable interest has developed in the use of targeted alpha-particle therapy for the treatment of micrometastases. Moreover, the use of helium beams is gaining momentum, especially for treating pediatric tumors. We analyzed the effects of alpha particles on bone marrow mesenchymal stromal cells (MSCs), which have a subpopulation of stem cells capable of generating adipocytes, chondrocytes, and osteocytes. Further, these cells contribute toward maintenance of homeostasis in the body. MSCs were irradiated with low and high doses of alpha particles or X-rays and a comparative biological analysis was performed. At a low dose (40 mGy), alpha particles exhibited a limited negative effect on the biology of MSCs compared with X-rays. No significant perturbation of cell cycle was observed, and a minimal increase in apoptosis or senescence was detected. Self-renewal was preserved as revealed by the CFU assay. On the contrary, with 2000 mGy alpha particles, we observed adverse effects on the vitality, functionality, and stemness of MSCs. These results are the consequence of different proportion of cells targeted by alpha particles or X-rays and the quality of induced DNA damage. The present study suggests that radiotherapy with alpha particles may spare healthy stem cells more efficaciously than X-ray treatments, an observation that should be taken into consideration by physicians while planning irradiation of tumor areas close to stem cell niches, such as bone marrow. J. Cell. Biochem. 118: 2993-3002, 2017. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Nicola Alessio
- Department of Experimental Medicine, Campania University "Luigi Vanvitelli", Naples, Italy
| | - Giuseppe Esposito
- Technology and Health Department, National Institute of Health, Rome, Italy.,National Institute of Nuclear Physics, Section Roma 1, Rome, Italy
| | - Giovanni Galano
- PSI Napoli Est - Laboratory UO, ASL Napoli 1 Centro, Naples, Italy
| | - Roberto De Rosa
- PSI Napoli Est - Radiology UO, ASL Napoli 1 Centro, Naples, Italy
| | - Pasquale Anello
- Technology and Health Department, National Institute of Health, Rome, Italy
| | - Gianfranco Peluso
- Institute of Agro-Environmental Biology and Forestry (IBAF), CNR, Naples, Italy
| | - Maria Antonella Tabocchini
- Technology and Health Department, National Institute of Health, Rome, Italy.,National Institute of Nuclear Physics, Section Roma 1, Rome, Italy
| | - Umberto Galderisi
- Department of Experimental Medicine, Campania University "Luigi Vanvitelli", Naples, Italy.,Institute of Agro-Environmental Biology and Forestry (IBAF), CNR, Naples, Italy.,Sbarro Institute for Cancer Research and Molecular Medicine, Center for Biotechnology, Temple University, Philadelphia, Pennsylvania
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16
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Christmann M, Boisseau C, Kitzinger R, Berac C, Allmann S, Sommer T, Aasland D, Kaina B, Tomicic MT. Adaptive upregulation of DNA repair genes following benzo(a)pyrene diol epoxide protects against cell death at the expense of mutations. Nucleic Acids Res 2016; 44:10727-10743. [PMID: 27694624 PMCID: PMC5159553 DOI: 10.1093/nar/gkw873] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Revised: 09/07/2016] [Accepted: 09/21/2016] [Indexed: 12/17/2022] Open
Abstract
A coordinated and faithful DNA damage response is of central importance for maintaining genomic integrity and survival. Here, we show that exposure of human cells to benzo(a)pyrene 9,10-diol-7,8-epoxide (BPDE), the active metabolite of benzo(a)pyrene (B(a)P), which represents a most important carcinogen formed during food preparation at high temperature, smoking and by incomplete combustion processes, causes a prompt and sustained upregulation of the DNA repair genes DDB2, XPC, XPF, XPG and POLH. Induction of these repair factors on RNA and protein level enhanced the removal of BPDE adducts from DNA and protected cells against subsequent BPDE exposure. However, through the induction of POLH the mutation frequency in the surviving cells was enhanced. Activation of these adaptive DNA repair genes was also observed upon B(a)P treatment of MCF7 cells and in buccal cells of human volunteers after cigarette smoking. Our data provide a rational basis for an adaptive response to polycyclic aromatic hydrocarbons, which occurs however at the expense of mutations that may drive cancer formation.
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Affiliation(s)
- Markus Christmann
- Department of Toxicology, University Medical Center Mainz, Obere Zahlbacher Strasse 67, D-55131 Mainz, Germany
| | - Catherine Boisseau
- Department of Toxicology, University Medical Center Mainz, Obere Zahlbacher Strasse 67, D-55131 Mainz, Germany
| | - Rebekka Kitzinger
- Department of Toxicology, University Medical Center Mainz, Obere Zahlbacher Strasse 67, D-55131 Mainz, Germany
| | - Christian Berac
- Department of Toxicology, University Medical Center Mainz, Obere Zahlbacher Strasse 67, D-55131 Mainz, Germany
| | - Sebastian Allmann
- Department of Toxicology, University Medical Center Mainz, Obere Zahlbacher Strasse 67, D-55131 Mainz, Germany
| | - Tina Sommer
- Department of Toxicology, University Medical Center Mainz, Obere Zahlbacher Strasse 67, D-55131 Mainz, Germany
| | - Dorthe Aasland
- Department of Toxicology, University Medical Center Mainz, Obere Zahlbacher Strasse 67, D-55131 Mainz, Germany
| | - Bernd Kaina
- Department of Toxicology, University Medical Center Mainz, Obere Zahlbacher Strasse 67, D-55131 Mainz, Germany
| | - Maja T Tomicic
- Department of Toxicology, University Medical Center Mainz, Obere Zahlbacher Strasse 67, D-55131 Mainz, Germany
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17
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Ng CYP, Kong EY, Kobayashi A, Suya N, Uchihori Y, Cheng SH, Konishi T, Yu KN. Non-induction of radioadaptive response in zebrafish embryos by neutrons. JOURNAL OF RADIATION RESEARCH 2016; 57:210-219. [PMID: 26850927 PMCID: PMC4915534 DOI: 10.1093/jrr/rrv089] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Revised: 09/13/2015] [Accepted: 11/03/2015] [Indexed: 06/05/2023]
Abstract
In vivo neutron-induced radioadaptive response (RAR) was studied using zebrafish (Danio rerio) embryos. The Neutron exposure Accelerator System for Biological Effect Experiments (NASBEE) facility at the National Institute of Radiological Sciences (NIRS), Japan, was employed to provide 2-MeV neutrons. Neutron doses of 0.6, 1, 25, 50 and 100 mGy were chosen as priming doses. An X-ray dose of 2 Gy was chosen as the challenging dose. Zebrafish embryos were dechorionated at 4 h post fertilization (hpf), irradiated with a chosen neutron dose at 5 hpf and the X-ray dose at 10 hpf. The responses of embryos were assessed at 25 hpf through the number of apoptotic signals. None of the neutron doses studied could induce RAR. Non-induction of RAR in embryos having received 0.6- and 1-mGy neutron doses was attributed to neutron-induced hormesis, which maintained the number of damaged cells at below the threshold for RAR induction. On the other hand, non-induction of RAR in embryos having received 25-, 50- and 100-mGy neutron doses was explained by gamma-ray hormesis, which mitigated neutron-induced damages through triggering high-fidelity DNA repair and removal of aberrant cells through apoptosis. Separate experimental results were obtained to verify that high-energy photons could disable RAR. Specifically, 5- or 10-mGy X-rays disabled the RAR induced by a priming dose of 0.88 mGy of alpha particles delivered to 5-hpf zebrafish embryos against a challenging dose of 2 Gy of X-rays delivered to the embryos at 10 hpf.
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Affiliation(s)
- Candy Y P Ng
- Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Ave., Kowloon Tong, Hong Kong
| | - Eva Y Kong
- Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Ave., Kowloon Tong, Hong Kong
| | - Alisa Kobayashi
- Research, Development and Support Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage, Chiba 263-8555, Japan Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan
| | - Noriyoshi Suya
- Research, Development and Support Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage, Chiba 263-8555, Japan
| | - Yukio Uchihori
- Research, Development and Support Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage, Chiba 263-8555, Japan
| | - Shuk Han Cheng
- Department of Biomedical Sciences, City University of Hong Kong, Tat Chee Ave., Kowloon Tong, Hong Kong State Key Laboratory in Marine Pollution, City University of Hong Kong, Tat Chee Ave., Kowloon Tong, Hong Kong
| | - Teruaki Konishi
- Research, Development and Support Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage, Chiba 263-8555, Japan
| | - Kwan Ngok Yu
- Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Ave., Kowloon Tong, Hong Kong State Key Laboratory in Marine Pollution, City University of Hong Kong, Tat Chee Ave., Kowloon Tong, Hong Kong
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18
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Calabrese EJ, Shamoun DY, Hanekamp JC. The Integration of LNT and Hormesis for Cancer Risk Assessment Optimizes Public Health Protection. HEALTH PHYSICS 2016; 110:256-259. [PMID: 26808876 DOI: 10.1097/hp.0000000000000382] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
This paper proposes a new cancer risk assessment strategy and methodology that optimizes population-based responses by yielding the lowest disease/tumor incidence across the entire dose continuum. The authors argue that the optimization can be achieved by integrating two seemingly conflicting models; i.e., the linear no-threshold (LNT) and hormetic dose-response models. The integration would yield the optimized response at a risk of 10 with the LNT model. The integrative functionality of the LNT and hormetic dose response models provides an improved estimation of tumor incidence through model uncertainty analysis and major reductions in cancer incidence via hormetic model estimates. This novel approach to cancer risk assessment offers significant improvements over current risk assessment approaches by revealing a regulatory sweet spot that maximizes public health benefits while incorporating practical approaches for model validation.
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Affiliation(s)
- Edward J Calabrese
- *School of Public Health & Health Sciences, Department of Environmental Health Sciences, Morrill I N344, University of Massachusetts, Amherst, MA 01003; †Research Fellow, Mercatus Center, George Mason University, 3434 Washington Blvd, Arlington, VA 22201; ‡University College Roosevelt, Lange Noordstraat 1, NL-4331 CB Middelburg, The Netherlands
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19
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Toprani SM, Das B. Radio-adaptive response of base excision repair genes and proteins in human peripheral blood mononuclear cells exposed to gamma radiation. Mutagenesis 2015; 30:663-76. [PMID: 25958388 DOI: 10.1093/mutage/gev032] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Radio-adaptive response is a mechanism whereby a low-dose exposure (priming dose) induces resistance to a higher dose (challenging dose) thus significantly reducing its detrimental effects. Radiation-induced DNA damage gets repaired through various DNA repair pathways in human cells depending upon the type of lesion. The base excision repair (BER) pathway repairs radiation-induced base damage, abasic sites and single-strand breaks in cellular DNA. In the present study, an attempt has been made to investigate the involvement of BER genes and proteins in the radio-adaptive response in human resting peripheral blood mononuclear cells (PBMC). Venous blood samples were collected from 20 randomly selected healthy male individuals with written informed consent. PBMC were isolated and irradiated at a priming dose of 0.1 Gy followed 4h later with a challenging dose of 2.0 Gy (primed cells). Quantitation of DNA damage was done using the alkaline comet assay immediately and expression profile of BER genes and proteins were studied 30 min after the challenging dose using real-time quantitative polymerase chain reaction and western blot, respectively. The overall result showed significant (P ≤ 0.05) reduction of DNA damage in terms of percentage of DNA in tail (%T) with a priming dose of 0.1 Gy followed by a challenging dose of 2.0 Gy after 4 h. Twelve individuals showed significant (P ≤ 0.05) reduction in %T whereas eight individuals showed marginal reduction in DNA damage that was not statistically significant. However, at the transcriptional level, BER genes such as APE1, FEN1 and LIGASE1 showed significant (P ≤ 0.05) up-regulation in both groups. Significant (P ≤ 0.05) up-regulation was also observed at the protein level for OGG1, APE1, MBD4, FEN1 and LIGASE1 in primed cells. Up-regulation of some BER genes and proteins such as APE1, FEN1 and LIGASE1 in primed cells of resting PBMC is suggestive of active involvement of the BER pathway in radio-adaptive response.
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Affiliation(s)
- Sneh M Toprani
- Low Level Radiation Research Section, Radiation Biology and Health Sciences Division, Bio-Sciences Group, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India
| | - Birajalaxmi Das
- Low Level Radiation Research Section, Radiation Biology and Health Sciences Division, Bio-Sciences Group, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India
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20
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Mitchel REJ. Adaption By Low Dose Radiation Exposure: A Look at Scope and Limitations for Radioprotection. Dose Response 2015; 13:10.2203_dose-response.14-025.Mitchel. [PMID: 26672725 PMCID: PMC4674178 DOI: 10.2203/dose-response.14-025.mitchel] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The procedures and dose limitations used for radiation protection in the nuclear industry are founded on the assumption that risk is directly proportional to dose, without a threshold. Based on this idea that any dose, no matter how small, will increase risk, radiation protection regulations generally attempt to reduce any exposure to “as low as reasonably achievable” (ALARA). We know however, that these regulatory assumptions are inconsistent with the known biological effects of low doses. Low doses induce protective effects, and these adaptive responses are part of a general response to low stress. Adaptive responses have been tightly conserved during evolution, from single celled organisms up to humans, indicating their importance. Here we examine cellular and animal studies that show the influence of radiation induced protective effects on diverse diseases, and examine the radiation dose range that is effective for different tissues in the same animal. The concept of a dose window, with upper and lower effective doses, as well as the effect of multiple stressors and the influence of genetics will also be examined. The effect of the biological variables on low dose responses will be considered from the point of view of the limitations they may impose on any revised radiation protection regulations.
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Affiliation(s)
- Ron E J Mitchel
- Radiological Protection Research and Instrumentation, Atomic Energy of Canada Ltd. Chalk River Nuclear Laboratories, Chalk River, ON, Canada, K0J1J0
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21
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Nenoi M, Wang B, Vares G. In vivo radioadaptive response: a review of studies relevant to radiation-induced cancer risk. Hum Exp Toxicol 2015; 34:272-83. [PMID: 24925363 PMCID: PMC4442823 DOI: 10.1177/0960327114537537] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Radioadaptive response (RAR) describes phenomena where small conditioning doses of ionizing radiation (IR) reduce detrimental effects of subsequent higher IR doses. Current radiation protection regulations do not include RAR because of the large variability in expression among individuals and uncertainties of the mechanism. However, RAR should be regarded as an indispensable factor for estimation and control of individual IR sensitivity. In this article, RAR studies relevant to individual cancer risk are reviewed. Using various stains of mice, carcinogenic RAR has been demonstrated. Consistently much in vivo evidence for RAR with end points of DNA and chromosome damage is reported. Most in vivo RAR studies revealed efficient induction of RAR by chronic or repeated low-dose priming irradiation. Chronic IR-induced RAR was observed also in human individuals after environmental, occupational, and nuclear accident radiation exposure. These observations may be associated with an intrinsically distinct feature of in vivo experimental systems that mainly consist of nonproliferating mature cells. Alternatively, induction of RAR by gap junction-mediated bystander effects suggests that multicellular systems comprising densely communicating cells may be capable of responding to long-lasting low-dose-rate priming irradiation. Regulation by endocrine factors is also a plausible mechanism for RAR at an individual level. Emerging evidence suggests that glucocorticoids, known as stress hormones, participate in in vivo RAR induction following long-term low-dose-rate exposure to IR.
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Affiliation(s)
- M Nenoi
- Research Center for Radiation Protection, National Institute of Radiological Sciences, Inage-ku, Chiba, Japan
| | - B Wang
- Research Center for Radiation Protection, National Institute of Radiological Sciences, Inage-ku, Chiba, Japan
| | - G Vares
- Research Center for Radiation Protection, National Institute of Radiological Sciences, Inage-ku, Chiba, Japan
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22
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Seed TM, Inal CE, Singh VK. Radioprotection of hematopoietic progenitors by low dose amifostine prophylaxis. Int J Radiat Biol 2014; 90:594-604. [PMID: 24597748 PMCID: PMC4133974 DOI: 10.3109/09553002.2014.899450] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Purpose Amifostine is a highly efficacious cytoprotectant when administered in vivo at high doses. However, at elevated doses, drug toxicity manifests for general, non-clinical radioprotective purposes. Various strategies have been developed to avoid toxic side-effects: The simplest is reducing the dose. In terms of protecting hematopoietic tissues, where does this effective, non-toxic minimum dose lie? Material and methods C3H/HEN mice were administered varying doses of amifostine (25–100 mg/kg) 30 min prior to cobalt-60 irradiation and euthanized between 4–14 days for blood and bone marrow collection and analyses. Results Under steady-state, amifostine had little effect on bipotential and multi-potential marrow progenitors but marginally suppressed a more primitive, lineage negative progenitor subpopulation. In irradiated animals, prophylactic drug doses greater than 50 mg/kg resulted in significant regeneration of bipotential progenitors, moderate regeneration of multipotential progenitors, but no significant and consistent regeneration of more primitive progenitors. The low amifostine dose (25 mg/kg) failed to elicit consistent and positive, radioprotective actions on any of the progenitor subtypes. Conclusions Radioprotective doses for amifostine appear to lie between 25 and 50 mg/kg. Mature, lineage-restricted progenitors appear to be more responsive to the protective effects of low doses of amifostine than the more primitive, multipotential progenitors.
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Christmann M, Kaina B. Transcriptional regulation of human DNA repair genes following genotoxic stress: trigger mechanisms, inducible responses and genotoxic adaptation. Nucleic Acids Res 2013; 41:8403-20. [PMID: 23892398 PMCID: PMC3794595 DOI: 10.1093/nar/gkt635] [Citation(s) in RCA: 172] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
DNA repair is the first barrier in the defense against genotoxic stress. In recent years, mechanisms that recognize DNA damage and activate DNA repair functions through transcriptional upregulation and post-translational modification were the focus of intensive research. Most DNA repair pathways are complex, involving many proteins working in discrete consecutive steps. Therefore, their balanced expression is important for avoiding erroneous repair that might result from excessive base removal and DNA cleavage. Amelioration of DNA repair requires both a fine-tuned system of lesion recognition and transcription factors that regulate repair genes in a balanced way. Transcriptional upregulation of DNA repair genes by genotoxic stress is counteracted by DNA damage that blocks transcription. Therefore, induction of DNA repair resulting in an adaptive response is only visible through a narrow window of dose. Here, we review transcriptional regulation of DNA repair genes in normal and cancer cells and describe mechanisms of promoter activation following genotoxic exposures through environmental carcinogens and anticancer drugs. The data available to date indicate that 25 DNA repair genes are subject to regulation following genotoxic stress in rodent and human cells, but for only a few of them, the data are solid as to the mechanism, homeostatic regulation and involvement in an adaptive response to genotoxic stress.
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Affiliation(s)
- Markus Christmann
- Department of Toxicology, University Medical Center, Obere Zahlbacher Str. 67, D-55131 Mainz, Germany
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24
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Panagopoulos DJ, Johansson O, Carlo GL. Evaluation of specific absorption rate as a dosimetric quantity for electromagnetic fields bioeffects. PLoS One 2013; 8:e62663. [PMID: 23750202 PMCID: PMC3672148 DOI: 10.1371/journal.pone.0062663] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 03/22/2013] [Indexed: 11/18/2022] Open
Abstract
PURPOSE To evaluate SAR as a dosimetric quantity for EMF bioeffects, and identify ways for increasing the precision in EMF dosimetry and bioactivity assessment. METHODS We discuss the interaction of man-made electromagnetic waves with biological matter and calculate the energy transferred to a single free ion within a cell. We analyze the physics and biology of SAR and evaluate the methods of its estimation. We discuss the experimentally observed non-linearity between electromagnetic exposure and biological effect. RESULTS WE FIND THAT: a) The energy absorbed by living matter during exposure to environmentally accounted EMFs is normally well below the thermal level. b) All existing methods for SAR estimation, especially those based upon tissue conductivity and internal electric field, have serious deficiencies. c) The only method to estimate SAR without large error is by measuring temperature increases within biological tissue, which normally are negligible for environmental EMF intensities, and thus cannot be measured. CONCLUSIONS SAR actually refers to thermal effects, while the vast majority of the recorded biological effects from man-made non-ionizing environmental radiation are non-thermal. Even if SAR could be accurately estimated for a whole tissue, organ, or body, the biological/health effect is determined by tiny amounts of energy/power absorbed by specific biomolecules, which cannot be calculated. Moreover, it depends upon field parameters not taken into account in SAR calculation. Thus, SAR should not be used as the primary dosimetric quantity, but used only as a complementary measure, always reporting the estimating method and the corresponding error. Radiation/field intensity along with additional physical parameters (such as frequency, modulation etc) which can be directly and in any case more accurately measured on the surface of biological tissues, should constitute the primary measure for EMF exposures, in spite of similar uncertainty to predict the biological effect due to non-linearity.
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Pristov JB, Spasić M, Spasojević I. Converting low dose radiation to redox signaling. PLANT SIGNALING & BEHAVIOR 2013; 8:e23151. [PMID: 23299433 PMCID: PMC3657013 DOI: 10.4161/psb.23151] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Accepted: 12/06/2012] [Indexed: 06/01/2023]
Abstract
In contrast to the damaging effects of high doses, low dose radiation (UV, gamma) has been reported to provoke constructive changes in plants. However, the mechanisms by which plants recognize and respond to low dose radiation are not understood. We have shown recently that polygalacturonic acid, cell wall polysaccharide, converts the highly reactive product of radiation - hydroxyl radical into superoxide which may be further dismutated to hydrogen peroxide. Superoxide has been proposed to act as a signaling molecule, while hydrogen peroxide is known to be the key species in redox signaling cascades which are involved in the regulation of various physiological processes. Hence we propose that polygalacturonic acid may operate as radiation-signaling convertor. The outlined principles of radiation-sensing could also be valid for mammalian cells, with some other molecules mediating the conversion.
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Affiliation(s)
- Jelena Bogdanović Pristov
- Life Sciences Department; Institute for Multidisciplinary Research; University of Belgrade; Belgrade, Serbia
| | - Mihajlo Spasić
- Department of Physiology; Institute for Biological Research “Siniša Stanković”; University of Belgrade; Belgrade, Serbia
| | - Ivan Spasojević
- Life Sciences Department; Institute for Multidisciplinary Research; University of Belgrade; Belgrade, Serbia
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Wang B, Tanaka K, Ninomiya Y, Maruyama K, VarèS G, Eguchi-Kasai K, Nenoi M. Relieved residual damage in the hematopoietic system of mice rescued by radiation-induced adaptive response (Yonezawa Effect). JOURNAL OF RADIATION RESEARCH 2013; 54:45-51. [PMID: 22923746 PMCID: PMC3534278 DOI: 10.1093/jrr/rrs077] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Revised: 07/24/2012] [Accepted: 07/24/2012] [Indexed: 05/27/2023]
Abstract
Existence of adaptive response (AR) was previously demonstrated in C57BL/6J mice. Irradiations were performed by delivering a priming low dose of X-rays (0.50 Gy) in combination with a challenge high dose of accelerated carbon or neon ion particles. AR was characterized by significantly decreased mortality in the 30-day survival test. This mouse AR model (‘Yonezawa Effect’) was originally established by using X-rays as both the priming and challenge irradiations. The underlying mechanism was due to radio-resistance occurring in blood-forming tissues. In this study, we verified the existence of AR and further investigated residual damage in the hematopoietic system in surviving animals. Results showed that the priming low dose of X-rays could relieve the detrimental effects on the hematopoietic system. We observed both an improvement in the blood platelet count and the ratio of polychromatic erythrocytes (PCEs) to the sum of PCEs and normochromatic erythrocytes (NCEs) and a marked reduction of the incidences of micronucleated PCEs and micronucleated NCEs. These findings suggest that the priming low dose of low linear energy transfer (LET) X-rays induced a protective effect on the hematopoietic system, which may play an important role in both rescue from acute lethal damage (mouse killing) and prevention of late detrimental consequences (residual anhematopoiesis and delayed genotoxic effects) caused by exposure to a high challenge dose from low-LET (X-ray) or high-LET (carbon and neon ion) irradiations. These findings provide new knowledge of the characterization of the Yonezawa Effect by providing new insight into the mechanistic study of AR in vivo.
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Affiliation(s)
- Bing Wang
- Corresponding authors. Tel: +81-43-206-3093; Fax: +81-43-251-4582; (B. Wang); Tel: +81-43-206-3084; Fax: +81-43-255-6497; E-mail: (M. Nenoi)
| | | | | | | | | | | | - Mitsuru Nenoi
- Corresponding authors. Tel: +81-43-206-3093; Fax: +81-43-251-4582; (B. Wang); Tel: +81-43-206-3084; Fax: +81-43-255-6497; E-mail: (M. Nenoi)
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Tedesco I, Spagnuolo C, Russo M, Iannitti R, Nappo A, Russo GL. Protective Effect of γ-Irradiation Against Hypochlorous Acid-Induced Haemolysis in Human Erythrocytes. Dose Response 2012; 11:401-12. [PMID: 23983667 PMCID: PMC3748851 DOI: 10.2203/dose-response.12-025.tedesco] [Citation(s) in RCA: 1] [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
Radiations may trigger protective response within a threshold of doses applied. Exposures above an upper threshold are generally detrimental, while exposures below a lower threshold may or may not increase risks for health. We recently reported that a cellular protective response occurs in interventional cardiologists to counteract the oxidative damage caused by radiation. Here, we demonstrated in an in vitro model represented by whole blood of healthy donors γ-irradiated with 220-440 mGy, that haemolysis of erythrocytes induced by hypochlorous acid was reduced by 40%. The protection triggered by γ-radiations made erythrocytes more resistant to oxidative insult caused by hypochlorous acid which was induced 3 h after irradiation and involved biochemical changes in the synthesis and turnover of glutathione. Overall, the biochemical remodelling induced by exposure to γ-radiations might contribute to generate new guidelines in professionally exposed workers.
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Affiliation(s)
| | | | - Maria Russo
- Institute of Food Sciences, National Research Council, 83100, Avellino, Italy
| | - Roberta Iannitti
- Institute of Food Sciences, National Research Council, 83100, Avellino, Italy
| | - Annunziata Nappo
- Institute of Food Sciences, National Research Council, 83100, Avellino, Italy
| | - Gian Luigi Russo
- Institute of Food Sciences, National Research Council, 83100, Avellino, Italy
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Wang B, Ninomiya Y, Tanaka K, Maruyama K, Varès G, Eguchi-Kasai K, Nenoi M. Adaptive response of low linear energy transfer X-rays for protection against high linear energy transfer accelerated heavy ion-induced teratogenesis. ACTA ACUST UNITED AC 2012; 95:379-85. [PMID: 23109298 DOI: 10.1002/bdrb.21027] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Accepted: 09/18/2012] [Indexed: 11/06/2022]
Abstract
BACKGROUND Adaptive response (AR) of low linear energy transfer (LET) irradiations for protection against teratogenesis induced by high LET irradiations is not well documented. In this study, induction of AR by X-rays against teratogenesis induced by accelerated heavy ions was examined in fetal mice. METHODS Irradiations of pregnant C57BL/6J mice were performed by delivering a priming low dose from X-rays at 0.05 or 0.30 Gy on gestation day 11 followed one day later by a challenge high dose from either X-rays or accelerated heavy ions. Monoenergetic beams of carbon, neon, silicon, and iron with the LET values of about 15, 30, 55, and 200 keV/μm, respectively, were examined. Significant suppression of teratogenic effects (fetal death, malformation of live fetuses, or low body weight) was used as the endpoint for judgment of a successful AR induction. RESULTS Existence of AR induced by low-LET X-rays against teratogenic effect induced by high-LET accelerated heavy ions was demonstrated. The priming low dose of X-rays significantly reduced the occurrence of prenatal fetal death, malformation, and/or low body weight induced by the challenge high dose from either X-rays or accelerated heavy ions of carbon, neon or silicon but not iron particles. CONCLUSIONS Successful AR induction appears to be a radiation quality event, depending on the LET value and/or the particle species of the challenge irradiations. These findings would provide a new insight into the study on radiation-induced AR in utero.
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Affiliation(s)
- Bing Wang
- Radiation Risk Reduction Research Program, Research Center for Radiation Protection, National Institute of Radiological Sciences, Chiba, Japan.
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Eken A, Aydin A, Erdem O, Akay C, Sayal A, Somuncu İ. Induced antioxidant activity in hospital staff occupationally exposed to ionizing radiation. Int J Radiat Biol 2012; 88:648-53. [DOI: 10.3109/09553002.2012.702295] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Hertel-Aas T, Brunborg G, Jaworska A, Salbu B, Oughton DH. Effects of different gamma exposure regimes on reproduction in the earthworm Eisenia fetida (Oligochaeta). THE SCIENCE OF THE TOTAL ENVIRONMENT 2011; 412-413:138-147. [PMID: 22033357 DOI: 10.1016/j.scitotenv.2011.09.037] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Revised: 09/06/2011] [Accepted: 09/14/2011] [Indexed: 05/31/2023]
Abstract
Ecological risk assessment of ionising radiation requires knowledge about the responses of individuals and populations to chronic exposures, including situations when exposure levels change over time. The present study investigated processes such as recovery and the adaptive response with respect to reproduction endpoints in the earthworm Eisenia fetida exposed to (60)Co γ-radiation. Furthermore, a crossed experiment was performed to investigate the influence of F0 parental and F1 embryonic irradiation history on the response of irradiated or non-irradiated F1 offspring. Recovery: The sterility induced by sub-chronic exposure at 17 m Gy/h (accumulated dose: 25 Gy) was temporary, and 8 weeks after irradiation the worms had regained their reproductive capacity (number of viable offspring produced per adult per week). Adaptive response: Adult worms were continuously exposed at a low priming dose rate of 0.14 mGy/h for 12 weeks (accumulated dose: 0.24 Gy), followed by 14 weeks exposure at a challenge dose rate of 11 mGy/h. The results suggest a lack of adaptive response, since there were no significant differences in the effects on reproduction capacity between the primed and the unprimed groups after challenge doses ranging from 7.6 to 27 Gy. Crossed experiment: The effects of exposure at 11 mGy/h for 21 weeks on growth, sexual maturation and reproduction of offspring, derived either from parent worms and cocoons both exposed at 11 mGy/h, or from non-irradiated parents and cocoons (total accumulated dose 44 and 38 Gy, respectively) were compared. There were no significant differences between the two exposed offspring groups for any of the endpoints. The reproduction capacity was very low for both groups compared to the controls, but the reproduction seemed to be maintained at the reduced level, which could indicate acclimatisation or stabilisation. Finally, parental and embryonic exposures at 11 mGy/h did not affect reproduction in the F1 offspring as adults.
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Affiliation(s)
- Turid Hertel-Aas
- Department of Plant and Environmental Sciences, Norwegian University of Life Sciences, P.O. Box 5003, 1432 Aas, Norway.
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Smith RW, Mothersill C, Hinton T, Seymour CB. Exposure to low level chronic radiation leads to adaptation to a subsequent acute X-ray dose and communication of modified acute X-ray induced bystander signals in medaka (Japanese rice fish, Oryzias latipes). Int J Radiat Biol 2011; 87:1011-22. [DOI: 10.3109/09553002.2011.587861] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Richard W. Smith
- Medical Physics and Applied Radiation Sciences, McMaster University,
Hamilton, Ontario, Canada
| | - Carmel Mothersill
- Medical Physics and Applied Radiation Sciences, McMaster University,
Hamilton, Ontario, Canada
| | - Thomas Hinton
- Laboratoire de Radioécologie et d'Ecotoxicologie IRSN/DEI/SECRE (Bâtiment 159) Institut de Radioprotection et de Sûreté Nucléaire (IRSN) Centre de Cadarache Saint Paul-lez-Durance, France
| | - Colin B. Seymour
- Medical Physics and Applied Radiation Sciences, McMaster University,
Hamilton, Ontario, Canada
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Farcy E, Voiseux C, Robbes I, Lebel JM, Fievet B. Effect of Ionizing Radiation on the Transcription Levels of Cell Stress Marker Genes in the Pacific Oyster Crassostrea gigas. Radiat Res 2011; 176:38-48. [DOI: 10.1667/rr2525.1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Yao Y, Bilichak A, Golubov A, Kovalchuk I. Local infection with oilseed rape mosaic virus promotes genetic rearrangements in systemic Arabidopsis tissue. Mutat Res 2011; 709-710:7-14. [PMID: 21376739 DOI: 10.1016/j.mrfmmm.2011.02.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2010] [Revised: 02/14/2011] [Accepted: 02/15/2011] [Indexed: 05/24/2023]
Abstract
We have previously shown that local infection of tobacco plants with tobacco mosaic virus (TMV) or oilseed rape mosaic virus (ORMV) results in a systemic increase in the homologous recombination frequency (HRF). Here, we analyzed what other changes in the genome are triggered by pathogen infection. For the analysis of HRF, mutation frequency (MF) and microsatellite instability (MI), we used three different transgenic Arabidopsis lines carrying β-glucuronidase (GUS)-based substrates in their genome. We found that local infection of Arabidopsis with ORMV resulted in an increase of all three frequencies, albeit to differing degrees. The most prominent increase was observed in microsatellite instability. The increase in HRF was the lowest, although still statistically significant. The analysis of methylation of the 35S promoter and transgene expression showed that the greater instability of the transgene was not attributed to these changes. Strand breaks brought about a significant increase in non-treated tissues of infected plants. The expression of genes associated with various repair processes, such as KU70, RAD51, MSH2, DNA POL α and DNA POL δ, was also increased. To summarize, our data demonstrate that local ORMV infection destabilizes the genome in systemic tissues of Arabidopsis plants in various ways resulting in large rearrangements, point mutations and microsatellite instability.
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Affiliation(s)
- Youli Yao
- Department of Biological Sciences, University of Lethbridge, Lethbridge, T1K 3M4, Alberta, Canada.
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Calabrese V, Cornelius C, Dinkova-Kostova AT, Calabrese EJ, Mattson MP. Cellular stress responses, the hormesis paradigm, and vitagenes: novel targets for therapeutic intervention in neurodegenerative disorders. Antioxid Redox Signal 2010; 13:1763-811. [PMID: 20446769 PMCID: PMC2966482 DOI: 10.1089/ars.2009.3074] [Citation(s) in RCA: 585] [Impact Index Per Article: 41.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2009] [Revised: 04/27/2010] [Accepted: 05/01/2010] [Indexed: 12/22/2022]
Abstract
Despite the capacity of chaperones and other homeostatic components to restore folding equilibrium, cells appear poorly adapted for chronic oxidative stress that increases in cancer and in metabolic and neurodegenerative diseases. Modulation of endogenous cellular defense mechanisms represents an innovative approach to therapeutic intervention in diseases causing chronic tissue damage, such as in neurodegeneration. This article introduces the concept of hormesis and its applications to the field of neuroprotection. It is argued that the hormetic dose response provides the central underpinning of neuroprotective responses, providing a framework for explaining the common quantitative features of their dose-response relationships, their mechanistic foundations, and their relationship to the concept of biological plasticity, as well as providing a key insight for improving the accuracy of the therapeutic dose of pharmaceutical agents within the highly heterogeneous human population. This article describes in mechanistic detail how hormetic dose responses are mediated for endogenous cellular defense pathways, including sirtuin and Nrf2 and related pathways that integrate adaptive stress responses in the prevention of neurodegenerative diseases. Particular attention is given to the emerging role of nitric oxide, carbon monoxide, and hydrogen sulfide gases in hormetic-based neuroprotection and their relationship to membrane radical dynamics and mitochondrial redox signaling.
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Cheng GH, Wu N, Jiang DF, Zhao HG, Zhang Q, Wang JF, Gong SL. Increased levels of p53 and PARP-1 in EL-4 cells probably related with the immune adaptive response induced by low dose ionizing radiation in vitro. BIOMEDICAL AND ENVIRONMENTAL SCIENCES : BES 2010; 23:487-495. [PMID: 21315248 DOI: 10.1016/s0895-3988(11)60012-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2009] [Accepted: 08/20/2010] [Indexed: 05/30/2023]
Abstract
OBJECTIVE This paper is to explore the DNA repair mechanism of immune adaptive response (AR) induced by low dose radiation (LDR), the changes of mRNA levels and protein expressions of p53, ATM, DNA-PK catalytic subunit (DNA-PKcs) and PARP-1 genes in the LDR-induced AR in EL-4 cells. METHODS The apoptosis and cell cycle progression of EL-4 cells were detected by flow cytometry in 12 h after the cells received the pre-exposure of 0.075 Gy X-rays (inductive dose, D1) and the succeeding high dose irradiation (challenge dose, D2; 1.0, 1.5, and 2.0 Gy X-rays, respectively) with or without wortmannin (inhibitor of ATM and DNA-PK) and 3-aminobenzamid (inhibitor of PARP-1). And the protein expressions and mRNA levels related to these genes were detected with flow cytometry and reverse transcription-polymerase chain reaction in 12 h after irradiation with D2. RESULTS The mRNA and protein expressions of p53 and PARP-1 in EL-4 cells in the D1 + D2 groups were much lower than those in the D2 groups, and those of PARP-1 in the 3-AB + D2 and the 3-AB + D1 + D2 groups were much lower than those in the D2 and the D1 + D2 groups. The percentage of apoptotic EL-4 cells in the 3-AB + D1 + D2 groups was much higher than that in the D1 + D2 groups, that in the G₀/G₁ and the G₂ + M phases was much higher, and that in the S phase were much lower. Although the ATM and DNA-PKcs mRNA and protein expressions in wortmannin + D1 + D2 groups were much lower than those in the D1 + D2 groups, there were no significant changes in the apoptosis and cell cycle progression between the wortmannin + D1 + D2 and the D1 + D2 groups. CONCLUSION PARP-1 and p53 might play important roles in AR induced by LDR.
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Affiliation(s)
- Guang-Hui Cheng
- Department of Radiotherapy, China-Japan Union Hospital, Jilin University, Changchun 130033, Jilin, China
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Wang B, Tanaka K, Varès G, Shang Y, Fujita K, Ninomiya Y, Nakajima T, Eguchi-Kasai K, Nenoi M. X-Ray-Induced Radioresistance against High-LET Radiations from Accelerated Heavy Ions in Mice. Radiat Res 2010; 174:532-6. [DOI: 10.1667/rr2133.1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Leonard BE, Thompson RE, Beecher GC. Human Lung Cancer Risks from Radon - Part III - Evidence of Influence of Combined Bystander and Adaptive Response Effects on Radon Case-Control Studies - A Microdose Analysis. Dose Response 2010; 10:415-61. [PMID: 22942874 DOI: 10.2203/dose-response.09-059.leonard] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [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 (1999) report 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, in particular the potentially deleterious Bystander Effect (BE) and the potentially beneficial Adaptive Response radio-protection (AR). The case-control radon lung cancer risk data of the pooled 13 European countries radon study (Darby et al 2005, 2006) and the 8 North American pooled study (Krewski et al 2005, 2006) have been evaluated. The large variation in the odds ratios of lung cancer from radon risk is reconciled, based on the large variation in geological and ecological conditions and variation in the degree of adaptive response radio-protection against the bystander effect induced lung damage. The analysis clearly shows Bystander Effect radon lung cancer induction and Adaptive Response reduction in lung cancer in some geographical regions. It is estimated that for radon levels up to about 400 Bq m(-3) there is about a 30% probability that no human lung cancer risk from radon will be experienced and a 20% probability that the risk is below the zero-radon, endogenic spontaneous or perhaps even genetically inheritable lung cancer risk rate. The BEIR VI (1999) and EPA (2003) estimates of human lung cancer deaths from radon are most likely significantly excessive. The assumption of linearity of risk, by the Linear No-Threshold Model, with increasing radon exposure is invalid.
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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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Leonard BE, Thompson RE, Beecher GC. Human Lung Cancer Risks from Radon - Part II - Influence from Combined Adaptive Response and Bystander Effects - A Microdose Analysis. Dose Response 2010; 9:502-53. [PMID: 22461760 DOI: 10.2203/dose-response.09-058.leonard] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
In the prior Part I, the potential influence of the low level alpha radiation induced bystander effect (BE) on human lung cancer risks was examined. Recent analysis of adaptive response (AR) research results with a Microdose Model has shown that single low LET radiation induced charged particles traversals through the cell nucleus activates AR. We have here conducted an analysis based on what is presently known about adaptive response and the bystander effect (BE) and what new research is needed that can assist in the further evaluation human cancer risks from radon. We find that, at the UNSCEAR (2000) worldwide average human exposures from natural background and man-made radiations, the human lung receives about a 25% adaptive response protection against the radon alpha bystander damage. At the UNSCEAR (2000) minimum range of background exposure levels, the lung receives minimal AR protection but at higher background levels, in the high UNSCEAR (2000) range, the lung receives essentially 100% protection from both the radon alpha damage and also the endogenic, spontaneously occurring, potentially carcinogenic, lung cellular damage.
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Carlisle SM, Burchart PA, Mitchel REJ. Cancer and non-cancer risks in normal and cancer-prone Trp53 heterozygous mice exposed to high-dose radiation. Radiat Res 2010; 173:40-8. [PMID: 20041758 DOI: 10.1667/rr1875.1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
This report tests the hypotheses that cancer proneness elevates risk from a high radiation exposure and that the risk response to high doses is qualitatively similar to that from low doses. Groups of about 170 female mice heterozygous for Trp53 (Trp53(+/-)) and their normal female littermates (Trp53(+/+)) were exposed at 7-8 weeks of age to (60)Co gamma-radiation doses of 0, 1, 2, 3 or 4 Gy at a high dose rate (0.5 Gy/min) or 4 Gy at a low dose rate (0.5 mGy/min). In the absence of radiation exposure, Trp53 heterozygosity reduced life span approximately equally for death from either cancer or non-cancer disease. Heterozygosity alone produced a 1.5-fold greater shortening of life span than a 4-Gy acute exposure. Per unit dose, life shortening from cancer or non-cancer disease was the same for normal mice and Trp53 heterozygous animals, indicating that, contrary to previous reports, Trp53 heterozygosity did not confer radiation sensitivity to high doses of gamma rays. In Trp53(+/-) mice with cancer, life shortening from acute doses up to 4 Gy was related to both increased tumor formation and decreased tumor latency. A similar tumor response was observed in normal mice, but only up to 2 Gy, indicating that above 2 Gy, normal Trp53 function protected against tumor initiation, and further life shortening reflected only decreased latency for cancer and non-cancer disease. Dose-rate reduction factors were 1.7-3.0 for both genotypes and all end points. We conclude that Trp53 gene function influences both cancer and non-cancer mortality in unexposed female mice and that Trp53-associated cancer proneness in vivo is not correlated with elevated radiation risk. Increased risk from high acute radiation doses contrasts with the decreased risk seen previously after low doses of radiation in both Trp53 normal and heterozygous female mice.
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Affiliation(s)
- S M Carlisle
- Radiation Protection Research and Instrumentation Branch, Atomic Energy of Canada Limited, Chalk River Laboratories, Chalk River, Ontario K0J 1J0, Canada
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Abstract
Adaptive responses to low doses of low LET radiation occur in all organisms thus far examined, from single cell lower eukaryotes to mammals. These responses reduce the deleterious consequences of DNA damaging events, including radiation-induced or spontaneous cancer and non-cancer diseases in mice. The adaptive response in mammalian cells and mammals operates within a certain window that can be defined by upper and lower dose thresholds, typically between about 1 and 100 mGy for a single low dose rate exposure. However, these thresholds for protection are not a fixed function of total dose, but also vary with dose rate, additional radiation or non-radiation stressors, tissue type and p53 functional status. Exposures above the upper threshold are generally detrimental, while exposures below the lower threshold may or may not increase either cancer or non-cancer disease risk.
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Affiliation(s)
- Ronald E J Mitchel
- Radiation Protection Research and Instrumentation Branch, Atomic Energy of Canada Limited, Chalk River Laboratories, Chalk River, ON Canada
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Abstract
Current radiation protection regulatory limits are based on the linear non-threshold (LNT) theory using health data from atomic bombing survivors. Studies in recent years sparked debate on the validity of the theory, especially at low doses. The present LNT overestimates radiation risks since the dosimetry included only acute gammas and neutrons; the role of other bomb-caused factors, e.g. fallout, induced radioactivity, thermal radiation (UVR), electromagnetic pulse (EMP), and blast, were excluded. Studies are proposed to improve the dose-response relationship.
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Affiliation(s)
- C R Aleta
- Lackierergasse 3/4, A1090, Vienna, Austria.
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Abstract
The hormesis concept has broad implications for biology and the biomedical sciences. This perspective on hormesis concentrates on toxicology and toxicological risk assessment and secondarily explores observations from other fields. It considers the varied manifestations of hormesis in the context of a broad family of biological stress responses. Evidence for hormesis is reviewed, and the hormesis model is contrasted with more widely accepted dose-response models in toxicology: a linear nonthreshold (LNT) model for mutagenesis and carcinogenesis, and a threshold model for most other toxicologic effects. Scientific, philosophical, and political objections to the hormesis concept are explored, and complications in the hormesis concept are analyzed. The review concludes with a perspective on the current state of hormesis and challenges that the hormesis model poses for risk assessment.
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Affiliation(s)
- George R Hoffmann
- Department of Biology, College of the Holy Cross, One College Street, Worcester, MA 01610-2395, USA.
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Mitchel REJ, Burchart P, Wyatt H. A Lower Dose Threshold for theIn VivoProtective Adaptive Response to Radiation. Tumorigenesis in Chronically Exposed Normal andTrp53Heterozygous C57BL/6 Mice. Radiat Res 2008; 170:765-75. [DOI: 10.1667/rr1414.1] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2008] [Accepted: 05/29/2008] [Indexed: 11/03/2022]
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Kilemade M, Lemon J, Boreham D. Characteristics of the adaptive response in cultured salmon cells exposed to ionizing radiation. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2008; 49:165-172. [PMID: 18095328 DOI: 10.1002/em.20354] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The aim of this study was to investigate the influence of "priming" doses of ionizing irradiation on salmon cell survival in vitro prior to being challenged with subsequent higher doses. A radiation-induced adaptive response (AR) was examined in the Chinook salmon embryo cell line (CHSE-214). Cells were initially irradiated with a range of priming (conditioning) doses of (60)Co gamma (gamma) rays (0.25-0.75 Gy), followed by a challenge dose of 7.50 Gy at intervals of 24, 48, and 72 hr. The AR was assessed using a colony-forming assay. Cell survival was determined by counting the number of colonies (viable clones) after 40 days of culture. This study revealed that cells that received a priming dose of 0.50 Gy before delivering the higher challenge dose became more radiation resistant with an increase in cell survival of 29% over cells receiving the challenge dose alone. The cells showed maximum resistance to ionizing radiation when the priming dose was given 72 hr prior to the higher challenge dose. This study is one of the first to demonstrate an AR using an in vitro piscine system, and is generally consistent with other studies of both in vitro and in vivo systems across the taxa.
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Affiliation(s)
- Michael Kilemade
- Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, Ontario, Canada
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Scott BR. Low-dose-radiation stimulated natural chemical and biological protection against lung cancer. Dose Response 2008; 6:299-318. [PMID: 18846259 DOI: 10.2203/dose-response.07-025.scott] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Research is being conducted world-wide related to chemoprevention of future lung cancer among smokers. The fact that low doses and dose rates of some sparsely ionizing forms of radiation (e.g., x rays, gamma rays, and beta radiation) stimulate transient natural chemical and biological protection against cancer in high-risk individuals is little known. The cancer preventative properties relate to radiation adaptive response (radiation hormesis) and involve stimulated protective biological signaling (a mild stress response). The biological processes associated with the protective signaling are now better understood and include: increased availability of efficient DNA double-strand break repair (p53-related and in competition with normal apoptosis), stimulated auxiliary apoptosis of aberrant cells (presumed p53-independent), and stimulated protective immune functions. This system of low-dose radiation activated natural protection (ANP) requires an individual-specific threshold level of mild stress and when invoked can efficiently prevent the occurrence of cancers as well as other genomic-instability-associated diseases. In this paper, low, essentially harmless doses of gamma rays spread over an extended period are shown via use of a biological-based, hormetic relative risk (HRR) model to be highly efficient in preventing lung cancer induction by alpha radiation from inhaled plutonium.
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Affiliation(s)
- B R Scott
- Lovelace Respiratory Research Institute, 2425 Ridgecrest Drive SE, Albuquerque, NM 87108, USA.
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Little MP, Heidenreich WF, Moolgavkar SH, Schöllnberger H, Thomas DC. Systems biological and mechanistic modelling of radiation-induced cancer. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2008; 47:39-47. [PMID: 18097677 PMCID: PMC2226195 DOI: 10.1007/s00411-007-0150-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2007] [Accepted: 12/03/2007] [Indexed: 05/07/2023]
Abstract
This paper summarises the five presentations at the First International Workshop on Systems Radiation Biology that were concerned with mechanistic models for carcinogenesis. The mathematical description of various hypotheses about the carcinogenic process, and its comparison with available data is an example of systems biology. It promises better understanding of effects at the whole body level based on properties of cells and signalling mechanisms between them. Of these five presentations, three dealt with multistage carcinogenesis within the framework of stochastic multistage clonal expansion models, another presented a deterministic multistage model incorporating chromosomal aberrations and neoplastic transformation, and the last presented a model of DNA double-strand break repair pathways for second breast cancers following radiation therapy.
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Affiliation(s)
- M P Little
- Department of Epidemiology and Public Health, Imperial College Faculty of Medicine, London W2 1PG, UK.
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Abstract
The Linear No Threshold (LNT) hypothesis states that ionizing radiation risk is directly proportional to dose, without a threshold. This hypothesis, along with a number of additional derived or auxiliary concepts such as radiation and tissue type weighting factors, and dose rate reduction factors, are used to calculate radiation risk estimates for humans, and are therefore fundamental for radiation protection practices. This system is based mainly on epidemiological data of cancer risk in human populations exposed to relatively high doses (above 100 mSv), with the results linearly extrapolated back to the low doses typical of current exposures. The system therefore uses dose as a surrogate for risk. There is now a large body of information indicating that, at low doses, the LNT hypothesis, along with most of the derived and auxiliary concepts, is incorrect. The use of dose as a predictor of risk needs to be re-examined and the use of dose limits, as a means of limiting risk needs to be re-evaluated. This re-evaluation could lead to large changes in radiation protection practices.
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Affiliation(s)
- R E J Mitchel
- Radiation Biology and Health Physics Branch, Atomic Energy of Canada Limited, Chalk River, Ontario, Canada.
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Abstract
Apoptosis induced in non-hit bystander cells is an important biological mechanism which operates after exposure to low doses of low-LET radiation. This process was implemented into a deterministic multistage model for in vitro neoplastic transformation: the State-Vector Model (SVM). The new model is tested on two data sets that show a reduction of the transformation frequency below the spontaneous level after exposure of the human hybrid cell line CGL1 to low doses of gamma-radiation. Stronger protective effects are visible in the data for delayed plating while the data for immediate plating show more of an LNT-like dose-response curve. It is shown that the model can describe both data sets. The calculation of the time-dependent numerical solution of the model also allows to obtain information about the time-dependence of the protective apoptosis-mediated process after low dose exposures. These findings are compared with experimental observations after high dose exposures.
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Affiliation(s)
- Helmut Schöllnberger
- Department of Materials Engineering and Physics, Division of Physics and Biophysics, University of Salzburg, Hellbrunnerstrasse 34, Salzburg, Austria.
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Abstract
Risk prediction and dose limits for human radiation exposure are based on the assumption that risk is proportional to total dose. However, there is concern about the appropriateness of those limits for people who may be genetically cancer prone. The TP53 gene product functions in regulatory pathways for DNA repair, cell cycle checkpoints and apoptosis, processes critical in determining ionizing radiation risk for both carcinogenesis and teratogenesis. Mice that are deficient in TP53 function are cancer prone. This review examines the influence of variations in TP53 gene activity on cancer and teratogenic risk in mice exposed to radiation in vivo, and compares those observations to the assumptions and predictions of radiation risk inherent in the existing system of radiation protection. Current assumptions concerning a linear response with dose, dose additivity, lack of thresholds and dose rate reduction factors all appear incorrect at low doses. TP53 functional variations can further modify radiation risk from either high or low doses, or risk from radiation exposures combined with other stresses, and those modifications can result in both quantitative and qualitative changes in risk.
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Affiliation(s)
- R E J Mitchel
- Radiation Biology and Health Physics Branch, Atomic Energy of Canada Limited, Chalk River, Ontario, Canada.
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