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Cherednichenko O, Pilyugina A, Nuraliev S, Azizbekova D. Persons chronically exposed to low doses of ionizing radiation: A cytogenetic dosimetry study. MUTATION RESEARCH. GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2024; 894:503728. [PMID: 38432778 DOI: 10.1016/j.mrgentox.2024.503728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Revised: 01/10/2024] [Accepted: 01/13/2024] [Indexed: 03/05/2024]
Abstract
The dosimetry and control of exposure for individuals chronically exposed to ionizing radiation are important and complex issues. Assessment may be optimized by evaluating individual adaptation and radiosensitivity, but it is not possible for a single model to account for all relevant parameters. Our goal was to develop approaches for the calculation of doses for persons chronically exposed to ionizing radiation, taking their radiosensitivities into consideration. On the basis of ex vivo radiation of blood samples, dose-effect models were constructed for dose ranges 0.01-2.0 and 0.01-0.4 Gy, using different cytogenetic criteria. The frequencies of "dicentric chromosomes and rings" at low doses are too low to have predictive value. The different responses of subjects to radiation made it possible to categorize them according to their radiosensitivities and to generate separate dose-effect curves for radiosensitive, average, and radioresistant individuals, reducing the amount of error in retrospective dosimetry.
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Affiliation(s)
- Oksana Cherednichenko
- Laboratory of Genetic Monitoring, Institute of Genetics and Physiology, Almaty 050060, Kazakhstan.
| | - Anastassiya Pilyugina
- Laboratory of Genetic Monitoring, Institute of Genetics and Physiology, Almaty 050060, Kazakhstan
| | - Serikbai Nuraliev
- Laboratory of Genetic Monitoring, Institute of Genetics and Physiology, Almaty 050060, Kazakhstan
| | - Dinara Azizbekova
- Laboratory of Genetic Monitoring, Institute of Genetics and Physiology, Almaty 050060, Kazakhstan
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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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Boretti A. There is no reason to persist in the linear no-threshold (LNT) assumption. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2023; 266-267:107239. [PMID: 37393723 DOI: 10.1016/j.jenvrad.2023.107239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 06/21/2023] [Accepted: 06/27/2023] [Indexed: 07/04/2023]
Affiliation(s)
- Alberto Boretti
- Johnsonville Road, Johnsonville, Wellington, 6037, New Zealand.
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Hanson I, Pitman KE, Edin NFJ. The Role of TGF-β3 in Radiation Response. Int J Mol Sci 2023; 24:ijms24087614. [PMID: 37108775 PMCID: PMC10141893 DOI: 10.3390/ijms24087614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 04/18/2023] [Accepted: 04/19/2023] [Indexed: 04/29/2023] Open
Abstract
Transforming growth factor-beta 3 (TGF-β3) is a ubiquitously expressed multifunctional cytokine involved in a range of physiological and pathological conditions, including embryogenesis, cell cycle regulation, immunoregulation, and fibrogenesis. The cytotoxic effects of ionizing radiation are employed in cancer radiotherapy, but its actions also influence cellular signaling pathways, including that of TGF-β3. Furthermore, the cell cycle regulating and anti-fibrotic effects of TGF-β3 have identified it as a potential mitigator of radiation- and chemotherapy-induced toxicity in healthy tissue. This review discusses the radiobiology of TGF-β3, its induction in tissue by ionizing radiation, and its potential radioprotective and anti-fibrotic effects.
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Affiliation(s)
- Ingunn Hanson
- Department of Physics, University of Oslo, 0371 Oslo, Norway
| | | | - Nina F J Edin
- Department of Physics, University of Oslo, 0371 Oslo, Norway
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Low-Dose Radiation Therapy (LDRT) against Cancer and Inflammatory or Degenerative Diseases: Three Parallel Stories with a Common Molecular Mechanism Involving the Nucleoshuttling of the ATM Protein? Cancers (Basel) 2023; 15:cancers15051482. [PMID: 36900274 PMCID: PMC10000719 DOI: 10.3390/cancers15051482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2023] [Revised: 02/18/2023] [Accepted: 02/23/2023] [Indexed: 03/02/2023] Open
Abstract
Very early after their discovery, X-rays were used in multiple medical applications, such as treatments against cancer, inflammation and pain. Because of technological constraints, such applications involved X-ray doses lower than 1 Gy per session. Progressively, notably in oncology, the dose per session increased. However, the approach of delivering less than 1 Gy per session, now called low-dose radiation therapy (LDRT), was preserved and is still applied in very specific cases. More recently, LDRT has also been applied in some trials to protect against lung inflammation after COVID-19 infection or to treat degenerative syndromes such as Alzheimer's disease. LDRT illustrates well the discontinuity of the dose-response curve and the counterintuitive observation that a low dose may produce a biological effect higher than a certain higher dose. Even if further investigations are needed to document and optimize LDRT, the apparent paradox of some radiobiological effects specific to low dose may be explained by the same mechanistic model based on the radiation-induced nucleoshuttling of the ATM kinase, a protein involved in various stress response pathways.
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Almahwasi A. Low dose hyper-radiosensitivity in normal human cells. Radiat Phys Chem Oxf Engl 1993 2023. [DOI: 10.1016/j.radphyschem.2022.110523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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Mothersill C, Cocchetto A, Seymour C. Low Dose and Non-Targeted Radiation Effects in Environmental Protection and Medicine-A New Model Focusing on Electromagnetic Signaling. Int J Mol Sci 2022; 23:11118. [PMID: 36232421 PMCID: PMC9570230 DOI: 10.3390/ijms231911118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 09/16/2022] [Accepted: 09/17/2022] [Indexed: 11/17/2022] Open
Abstract
The role of signalling in initiating and perpetuating effects triggered by deposition of ionising radiation energy in parts of a system is very clear. Less clear are the very early steps involved in converting energy to chemical and biological effects in non-targeted parts of the system. The paper aims to present a new model, which could aid our understanding of the role of low dose effects in determining ultimate disease outcomes. We propose a key role for electromagnetic signals resulting from physico-chemical processes such as excitation decay, and acoustic waves. These lead to the initiation of damage response pathways such as elevation of reactive oxygen species and membrane associated changes in key ion channels. Critically, these signalling pathways allow coordination of responses across system levels. For example, depending on how these perturbations are transduced, adverse or beneficial outcomes may predominate. We suggest that by appreciating the importance of signalling and communication between multiple levels of organisation, a unified theory could emerge. This would allow the development of models incorporating time, space and system level to position data in appropriate areas of a multidimensional domain. We propose the use of the term "infosome" to capture the nature of radiation-induced communication systems which include physical as well as chemical signals. We have named our model "the variable response model" or "VRM" which allows for multiple outcomes following exposure to low doses or to signals from low dose irradiated cells, tissues or organisms. We suggest that the use of both dose and infosome in radiation protection might open up new conceptual avenues that could allow intrinsic uncertainty to be embraced within a holistic protection framework.
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Affiliation(s)
- Carmel Mothersill
- Department of Biology, McMaster University, Hamilton, ON L8S 4K1, Canada
| | - Alan Cocchetto
- National CFIDS Foundation, 285 Beach Ave., Hull, MA 02045-1602, USA
| | - Colin Seymour
- Department of Biology, McMaster University, Hamilton, ON L8S 4K1, Canada
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Polgár S, Schofield PN, Madas BG. Datasets of in vitro clonogenic assays showing low dose hyper-radiosensitivity and induced radioresistance. Sci Data 2022; 9:555. [PMID: 36075916 PMCID: PMC9458642 DOI: 10.1038/s41597-022-01653-3] [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: 05/21/2022] [Accepted: 08/19/2022] [Indexed: 11/19/2022] Open
Abstract
Low dose hyper-radiosensitivity and induced radioresistance are primarily observed in surviving fractions of cell populations exposed to ionizing radiation, plotted as the function of absorbed dose. Several biophysical models have been developed to quantitatively describe these phenomena. However, there is a lack of raw, openly available experimental data to support the development and validation of quantitative models. The aim of this study was to set up a database of experimental data from the public literature. Using Google Scholar search, 46 publications with 101 datasets on the dose-dependence of surviving fractions, with clear evidence of low dose hyper-radiosensitivity, were identified. Surviving fractions, their uncertainties, and the corresponding absorbed doses were digitized from graphs of the publications. The characteristics of the cell line and the irradiation were also recorded, along with the parameters of the linear-quadratic model and/or the induced repair model if they were provided. The database is available in STOREDB, and can be used for meta-analysis, for comparison with new experiments, and for development and validation of biophysical models. Measurement(s) | surviving fraction of cells | Technology Type(s) | optical microscopy | Factor Type(s) | absorbed dose | Sample Characteristic - Organism | Homo sapiens • Chinese hamster • Rattus sp. | Sample Characteristic - Environment | cell culture |
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Affiliation(s)
- Szabolcs Polgár
- Doctoral School of Physics, ELTE Eötvös Loránd University, Budapest, Hungary.,Environmental Physics Department, Centre for Energy Research, Budapest, Hungary
| | - Paul N Schofield
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
| | - Balázs G Madas
- Environmental Physics Department, Centre for Energy Research, Budapest, Hungary. .,Department of Physical Chemistry and Materials Science, Budapest University of Technology and Economics, Budapest, Hungary.
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Hanson I, Pitman KE, Altanerova U, Altaner Č, Malinen E, Edin NFJ. Low-Dose-Rate Radiation-Induced Secretion of TGF-β3 Together with an Activator in Small Extracellular Vesicles Modifies Low-Dose Hyper-Radiosensitivity through ALK1 Binding. Int J Mol Sci 2022; 23:ijms23158147. [PMID: 35897723 PMCID: PMC9332371 DOI: 10.3390/ijms23158147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Revised: 07/14/2022] [Accepted: 07/21/2022] [Indexed: 02/05/2023] Open
Abstract
Hyper-radiosensitivity (HRS) is the increased sensitivity to low doses of ionizing radiation observed in most cell lines. We previously demonstrated that HRS is permanently abolished in cells irradiated at a low dose rate (LDR), in a mechanism dependent on transforming growth factor β3 (TGF-β3). In this study, we aimed to elucidate the activation and receptor binding of TGF-β3 in this mechanism. T-47D cells were pretreated with inhibitors of potential receptors and activators of TGF-β3, along with addition of small extracellular vesicles (sEVs) from LDR primed cells, before their radiosensitivity was assessed by the clonogenic assay. The protein content of sEVs from LDR primed cells was analyzed with mass spectrometry. Our results show that sEVs contain TGF-β3 regardless of priming status, but only sEVs from LDR primed cells remove HRS in reporter cells. Inhibition of the matrix metalloproteinase (MMP) family prevents removal of HRS, suggesting an MMP-dependent activation of TGF-β3 in the LDR primed cells. We demonstrate a functional interaction between TGF-β3 and activin receptor like kinase 1 (ALK1) by showing that TGF-β3 removes HRS through ALK1 binding, independent of ALK5 and TGF-βRII. These results are an important contribution to a more comprehensive understanding of the mechanism behind TGF-β3 mediated removal of HRS.
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Affiliation(s)
- Ingunn Hanson
- Department of Physics, University of Oslo, 0371 Oslo, Norway; (K.E.P.); (E.M.); (N.F.J.E.)
- Correspondence:
| | - Kathinka E. Pitman
- Department of Physics, University of Oslo, 0371 Oslo, Norway; (K.E.P.); (E.M.); (N.F.J.E.)
| | - Ursula Altanerova
- Department of Stem Cell Preparation, St. Elisabeth Cancer Institute, 84505 Bratislava, Slovakia; (U.A.); (Č.A.)
| | - Čestmír Altaner
- Department of Stem Cell Preparation, St. Elisabeth Cancer Institute, 84505 Bratislava, Slovakia; (U.A.); (Č.A.)
- Cancer Research Institute, Slovak Academy of Sciences, Bratislava, 94505 Bratislava, Slovakia
| | - Eirik Malinen
- Department of Physics, University of Oslo, 0371 Oslo, Norway; (K.E.P.); (E.M.); (N.F.J.E.)
- Department of Medical Physics, Oslo University Hospital, 0379 Oslo, Norway
| | - Nina F. J. Edin
- Department of Physics, University of Oslo, 0371 Oslo, Norway; (K.E.P.); (E.M.); (N.F.J.E.)
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Ma CMC. Pulsed low dose-rate radiotherapy: radiobiology and dosimetry. Phys Med Biol 2022; 67. [DOI: 10.1088/1361-6560/ac4c2f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 01/17/2022] [Indexed: 11/12/2022]
Abstract
Abstract
Pulsed low dose-rate radiotherapy (PLDR) relies on two radiobiological findings, the hyper-radiosensitivity of tumor cells at small doses and the reduced normal tissue toxicity at low dose rates. This is achieved by delivering the daily radiation dose of 2 Gy in 10 sub-fractions (pulses) with a 3 min time interval, resulting in an effective low dose rate of 0.067 Gy min−1. In vitro cell studies and in vivo animal experiments demonstrated the therapeutic potential of PLDR treatments and provided useful preclinical data. Various treatment optimization strategies and delivery techniques have been developed for PLDR on existing linear accelerators. Preliminary results from early clinical studies have shown favorable outcomes for various treatment sites especially for recurrent cancers. This paper reviews the experimental findings of PLDR and dosimetric requirements for PLDR treatment planning and delivery, and summarizes major clinical studies on PLDR cancer treatments.
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Paganetti H. Mechanisms and Review of Clinical Evidence of Variations in Relative Biological Effectiveness in Proton Therapy. Int J Radiat Oncol Biol Phys 2022; 112:222-236. [PMID: 34407443 PMCID: PMC8688199 DOI: 10.1016/j.ijrobp.2021.08.015] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 07/14/2021] [Accepted: 08/10/2021] [Indexed: 01/03/2023]
Abstract
Proton therapy is increasingly being used as a radiation therapy modality. There is uncertainty about the biological effectiveness of protons relative to photon therapies as it depends on several physical and biological parameters. Radiation oncology currently applies a constant and generic value for the relative biological effectiveness (RBE) of 1.1, which was chosen conservatively to ensure tumor coverage. The use of a constant value has been challenged particularly when considering normal tissue constraints. Potential variations in RBE have been assessed in several published reviews but have mostly focused on data from clonogenic cell survival experiments with unclear relevance for clinical proton therapy. The goal of this review is to put in vitro findings in relation to clinical observations. Relevant in vivo pathways determining RBE for tumors and normal tissues are outlined, including not only damage to tumor cells and parenchyma but also vascular damage and immune response. Furthermore, the current clinical evidence of varying RBE is reviewed. The assessment can serve as guidance for treatment planning, personalized dose prescriptions, and outcome analysis.
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Affiliation(s)
- Harald Paganetti
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA.
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The Effect of High-Dose-Rate Pulsed Radiation on the Survival of Clinically Relevant Radioresistant Cells. Life (Basel) 2021; 11:life11121295. [PMID: 34947826 PMCID: PMC8708735 DOI: 10.3390/life11121295] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 11/20/2021] [Accepted: 11/22/2021] [Indexed: 12/20/2022] Open
Abstract
We demonstrated that low dose pulsed radiation (0.25 Gy) at a high-dose-rate, even for very short intervals (10 s), decreases cell survival to a greater extent than single exposure to a similar total dose and dose rate. The objective of this study was to clarify whether high-dose-rate pulsed radiation is effective against SAS-R, a clinically relevant radioresistant cell line. Cell survival following high-dose-rate pulsed radiation was evaluated via a colony assay. Flow cytometry was utilized to evaluate γH2AX, a molecular marker of DNA double-strand breaks and delayed reactive oxygen species (ROS) associated with radiation-induced apoptosis. Increased cytotoxicity was observed in SAS-R and parent SAS cells in response to high dose rate pulsed radiation compared to single dose, as determined by colony assays. Residual γH2AX in both cells subjected to high-dose-rate pulsed radiation showed a tendency to increase, with a significant increase observed in SAS cells at 72 h. In addition, high-dose-rate pulsed radiation increased delayed ROS more than the single exposure did. These results indicate that high-dose-rate pulsed radiation was associated with residual γH2AX and delayed ROS, and high-dose-rate pulsed radiation may be used as an effective radiotherapy procedure against radioresistant cells.
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Averbeck D, Rodriguez-Lafrasse C. Role of Mitochondria in Radiation Responses: Epigenetic, Metabolic, and Signaling Impacts. Int J Mol Sci 2021; 22:ijms222011047. [PMID: 34681703 PMCID: PMC8541263 DOI: 10.3390/ijms222011047] [Citation(s) in RCA: 70] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 09/24/2021] [Accepted: 10/08/2021] [Indexed: 12/15/2022] Open
Abstract
Until recently, radiation effects have been considered to be mainly due to nuclear DNA damage and their management by repair mechanisms. However, molecular biology studies reveal that the outcomes of exposures to ionizing radiation (IR) highly depend on activation and regulation through other molecular components of organelles that determine cell survival and proliferation capacities. As typical epigenetic-regulated organelles and central power stations of cells, mitochondria play an important pivotal role in those responses. They direct cellular metabolism, energy supply and homeostasis as well as radiation-induced signaling, cell death, and immunological responses. This review is focused on how energy, dose and quality of IR affect mitochondria-dependent epigenetic and functional control at the cellular and tissue level. Low-dose radiation effects on mitochondria appear to be associated with epigenetic and non-targeted effects involved in genomic instability and adaptive responses, whereas high-dose radiation effects (>1 Gy) concern therapeutic effects of radiation and long-term outcomes involving mitochondria-mediated innate and adaptive immune responses. Both effects depend on radiation quality. For example, the increased efficacy of high linear energy transfer particle radiotherapy, e.g., C-ion radiotherapy, relies on the reduction of anastasis, enhanced mitochondria-mediated apoptosis and immunogenic (antitumor) responses.
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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;
- Correspondence:
| | - Claire Rodriguez-Lafrasse
- Laboratory of Cellular and Molecular Radiobiology, PRISME, UMR CNRS 5822/IN2P3, IP2I, Lyon-Sud Medical School, University Lyon 1, 69921 Oullins, France;
- Department of Biochemistry and Molecular Biology, Lyon-Sud Hospital, Hospices Civils de Lyon, 69310 Pierre-Bénite, France
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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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Perez-Gelvez YNC, Camus AC, Bridger R, Wells L, Rhodes OE, Bergmann CW. Effects of chronic exposure to low levels of IR on Medaka ( Oryzias latipes): a proteomic and bioinformatic approach. Int J Radiat Biol 2021; 97:1485-1501. [PMID: 34355643 DOI: 10.1080/09553002.2021.1962570] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
PURPOSE Chronic exposure to ionizing radiation (IR) at low doses (<100 mGy) has been insufficiently studied to understand fully the risk to health. Relatively little knowledge exists regarding how species and healthy tissues respond at the protein level to chronic exposure to low doses of IR, and mass spectrometric-based profiling of protein expression is a powerful tool for studying changes in protein abundance. MATERIALS AND METHODS SDS gel electrophoresis, LC-MS/MS mass spectrometry-based approaches and bioinformatic data analytics were used to detect proteomic changes following chronic exposure to moderate/low doses of radiation in adults and normally developed Medaka fish (Oryzias latipes). RESULTS Significant variations in the abundance of proteins involved in thyroid hormone signaling and lipid metabolism were detected, which could be related to the gonadal regression phenotype observed after 21.04 mGy and 204.3 mGy/day exposure. The global proteomic change was towards overexpression of proteins in muscle and skin, while the opposite effect was observed in internal organs. CONCLUSION The present study provides information on the impacts of biologically relevant low doses of IR, which will be useful in future research for the identification of potential biomarkers of IR exposure and allow for a better assessment of radiation biosafety regulations.
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Affiliation(s)
- Yeni Natalia C Perez-Gelvez
- Carbohydrate Complex Research Center, Biochemistry and Molecular Biology, The University of Georgia, Athens, GA, USA
| | - Alvin C Camus
- College of Veterinary Medicine, Department of Pathology, The University of Georgia, Athens, GA, USA
| | - Robert Bridger
- Carbohydrate Complex Research Center, The University of Georgia, Athens, GA, USA
| | - Lance Wells
- Carbohydrate Complex Research Center, The University of Georgia, Athens, GA, USA
| | - Olin E Rhodes
- Savannah River Ecology Laboratory, Odum School of Ecology, The University of Georgia, Athens, GA, USA
| | - Carl W Bergmann
- Carbohydrate Complex Research Center, The University of Georgia, Athens, GA, USA
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17
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Radiation, a two-edged sword: From untoward effects to fractionated radiotherapy. Radiat Phys Chem Oxf Engl 1993 2021. [DOI: 10.1016/j.radphyschem.2020.108994] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Chauhan V, Vuong NQ, Bahia S, Nazemof N, Kumarathasan P. In vitro exposure of human lens epithelial cells to X-rays at varied dose-rates leads to protein-level changes relevant to cataractogenesis. Int J Radiat Biol 2020; 97:824-832. [PMID: 33164603 DOI: 10.1080/09553002.2020.1846819] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 10/24/2020] [Accepted: 10/30/2020] [Indexed: 12/12/2022]
Abstract
BACKGROUND Accumulated body of evidence shows that ionizing radiation increases the risk of cataracts. The mechanisms are not clear and the International Commission on Radiological Protection indicates a need for research into understanding the process, particularly at low doses and low dose rates of exposure. PURPOSE This study was designed to examine protein-level modifications in a human lens epithelial (HLE) cell-line following radiation exposures. MATERIALS AND METHODS HLE cell-line was subjected to X-irradiation at varied doses (0-5 Gy) and dose-rates (1.62 cGy/min and 38.2 cGy/min). Cells were collected 20 h post-exposure, lysed and proteins were clarified following fractionation by a molecular weight cut-off filtration method. Fractionated cellular proteins were enzymatically digested and subjected to mass spectrometry analysis. RESULTS Statistically significant radiation dose-related protein changes compared to the control group were identified. Heatmap and hierarchical clustering analysis showed dose-rate dependant responses. Pathway analysis mapped the proteins to biological functions of mitochondrial dysfunction, reactive oxygen species generation, cell death, cancer, organismal injury and amyloidosis. CONCLUSION Overall findings suggest that ionizing radiation exposure of HLE cells by mediating dose rate-dependant oxidative stress and cell death-related mechanisms, can be relevant to cataractogenesis.
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Affiliation(s)
- Vinita Chauhan
- Consumer and Clinical Radiation Protection Bureau, Healthy Environment and Consumer Safety Branch, Health Canada, Ottawa, Canada
| | - Ngoc Q Vuong
- Radiation Protection Bureau, Healthy Environment and Consumer Safety Branch, Health Canada, Ottawa, Canada
| | - Simran Bahia
- Consumer and Clinical Radiation Protection Bureau, Healthy Environment and Consumer Safety Branch, Health Canada, Ottawa, Canada
| | - Nazila Nazemof
- Interdisciplinary School of Health Sciences, University of Ottawa, Ottawa, Canada
| | - Premkumari Kumarathasan
- Interdisciplinary School of Health Sciences, University of Ottawa, Ottawa, Canada
- Environmental Health Sciences and Research Bureau, Healthy Environment and Consumer Safety Branch, Health Canada, Ottawa, Canada
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Genome-wide transcriptional effects of deletions of sulphur metabolism genes in Drosophila melanogaster. Redox Biol 2020; 36:101654. [PMID: 32769010 PMCID: PMC7414014 DOI: 10.1016/j.redox.2020.101654] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Accepted: 07/21/2020] [Indexed: 01/15/2023] Open
Abstract
In recent years, the gasotransmitter hydrogen sulphide (H2S), produced by the transsulphuration pathway, has been recognized as a biological mediator playing an important role under normal conditions and in various pathologies in both eukaryotes and prokaryotes. The transsulphuration pathway (TSP) includes the conversion of homocysteine to cysteine following the breakdown of methionine. In Drosophila melanogaster and other eukaryotes, H2S is produced by cystathionine β-synthase (CBS), cystathionine γ-lyase (CSE), and 3-mercaptopyruvate sulphurtransferase (MST). In the experiments performed in this study, we were able to explore the CRISPR/Cas9 technique to obtain single and double deletions in homozygotes of these three major genes responsible for H2S production in Drosophila melanogaster. In most cases, the deletion of one studied gene does not result in the compensatory induction of two other genes responsible for H2S production. Transcriptomic studies demonstrated that the deletions of the above CBS and CSE genes alter genome expression to different degrees, with a more pronounced effect being exerted by deletion of the CBS gene. Furthermore, the double deletion of both CBS and CSE resulted in a cumulative effect on transcription in the resulting strains. Overall, we found that the obtained deletions affect numerous genes involved in various biological pathways. Specifically, genes involved in the oxidative reduction process, stress-response genes, housekeeping genes, and genes participating in olfactory and reproduction are among the most strongly affected. Furthermore, characteristic differences in the response to the deletions of the studied genes are apparently organ-specific and have clear-cut sex-specific characteristics. Single and double deletions of the three genes responsible for the production of H2S helped to elucidate new aspects of the biological significance of this vital physiological mediator.
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Pulsed low dose-rate irradiation response in isogenic HNSCC cell lines with different radiosensitivity. Radiol Oncol 2020; 54:168-179. [PMID: 32229678 PMCID: PMC7276640 DOI: 10.2478/raon-2020-0015] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 03/01/2020] [Indexed: 12/16/2022] Open
Abstract
Background Management of locoregionally recurrent head and neck squamous cell carcinomas (HNSCC) is challenging due to potential radioresistance. Pulsed low-dose rate (PLDR) irradiation exploits phenomena of increased radiosensitivity, low-dose hyperradiosensitivity (LDHRS), and inverse dose-rate effect. The purpose of this study was to evaluate LDHRS and the effect of PLDR irradiation in isogenic HNSCC cells with different radiosensitivity. Materials and methods Cell survival after different irradiation regimens in isogenic parental FaDu and radioresistant FaDu-RR cells was determined by clonogenic assay; post irradiation cell cycle distribution was studied by flow cytometry; the expression of DNA damage signalling genes was assesed by reverse transcription-quantitative PCR. Results Radioresistant Fadu-RR cells displayed LDHRS and were more sensitive to PLDR irradiation than parental FaDu cells. In both cell lines, cell cycle was arrested in G2/M phase 5 hours after irradiation. It was restored 24 hours after irradiation in parental, but not in the radioresistant cells, which were arrested in G1-phase. DNA damage signalling genes were under-expressed in radioresistant compared to parental cells. Irradiation increased DNA damage signalling gene expression in radioresistant cells, while in parental cells only few genes were under-expressed. Conclusions We demonstrated LDHRS in isogenic radioresistant cells, but not in the parental cells. Survival of LDHRS-positive radioresistant cells after PLDR was significantly reduced. This reduction in cell survival is associated with variations in DNA damage signalling gene expression observed in response to PLDR most likely through different regulation of cell cycle checkpoints.
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Ma F, Gu X, Liu JQ, Mo LH, Yang G, Geng XR, Liu ZQ, Liu ZG, Yang PC. Inhibition of livin overcomes radioresistance in nasopharyngeal carcinoma cells. PLoS One 2020; 15:e0229272. [PMID: 32119704 PMCID: PMC7051067 DOI: 10.1371/journal.pone.0229272] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Accepted: 02/03/2020] [Indexed: 12/29/2022] Open
Abstract
Background and aims Radiotherapy is one of the major remedies for the treatment of cancer, including nasopharyngeal carcinoma (NPC). Radioresistance occurs very often in target cells that is a large drawback in cancer treated with radiotherapy. Livin involves the over-growth of cancer cells. This study aims to investigate the role of livin in the radioresistance formation in NPC cells. Methods NPC cell lines were exposed to small doses of irradiation to establish a cell model of radioresistance, in which the role of livin in the development of radioresistance was evaluated. Results The expression of livin was observed in NPC cells, which was significantly increased after exposing to small doses of irradiation. A negative correlation was detected between livin and Fas expression in NPC cells. Livin formed a complex with heat shock factor-1 (HSF1, the transcription factor of Fas) in NPC cells after irradiation, which sped up ubiquitination of HSF1. Livin was involved in suppressing Fas expression in NPC cells with radioresistance. Exposure to livin inhibitors prevented radioresistance development and overcame the established radioresistance in NPC cells. Conclusions Livin expression in NPC cells plays a critical role in the development of radioresistance. Depletion of livin increases the sensitiveness of NPC cells to irradiation. Target therapy against livin may have the translational potential for the treatment of NPC.
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Affiliation(s)
- Fei Ma
- Department of Traditional Chinese Medicine, Affiliated Shenzhen Maternity & Child Healthcare Hospital, Southern Medical University, Shenzhen, China
- Research Center of Allergy & Immunology, Shenzhen University School of Medicine, Shenzhen, China
| | - Xia Gu
- Research Center of Allergy & Immunology, Shenzhen University School of Medicine, Shenzhen, China
- Department of Respirology, Affiliated Hospital of Xinan Medical University, Luzhou, China
| | - Jiang-Qi Liu
- Department of Allergy, Longgang ENT Hospital & Shenzhen Key Laboratory of ENT, Institute of ENT, Shenzhen, China
| | - Li-Hua Mo
- Research Center of Allergy & Immunology, Shenzhen University School of Medicine, Shenzhen, China
| | - Gui Yang
- Department of Otolaryngology, Longgang Central Hospital, Shenzhen, China
| | - Xiao-Rui Geng
- Department of Allergy, Longgang ENT Hospital & Shenzhen Key Laboratory of ENT, Institute of ENT, Shenzhen, China
| | - Zhi-Qiang Liu
- Department of Allergy, Longgang ENT Hospital & Shenzhen Key Laboratory of ENT, Institute of ENT, Shenzhen, China
| | - Zhi-Gang Liu
- Research Center of Allergy & Immunology, Shenzhen University School of Medicine, Shenzhen, China
- * E-mail: (PCY); (ZGL)
| | - Ping-Chang Yang
- Research Center of Allergy & Immunology, Shenzhen University School of Medicine, Shenzhen, China
- Guangdong Provincial Key Laboratory of Regional Immunity and Diseases, Shenzhen, China
- * E-mail: (PCY); (ZGL)
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Schröder A, Kriesen S, Hildebrandt G, Manda K. First Insights into the Effect of Low-Dose X-Ray Irradiation in Adipose-Derived Stem Cells. Int J Mol Sci 2019; 20:ijms20236075. [PMID: 31810198 PMCID: PMC6928975 DOI: 10.3390/ijms20236075] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 11/26/2019] [Accepted: 11/28/2019] [Indexed: 02/07/2023] Open
Abstract
(1) Background: Emerging interest of physicians to use adipose-derived stem cells (ADSCs) for regenerative therapies and the fact that low-dose irradiation (LD-IR ≤ 0.1 Gy) has been reported to enhance the proliferation of several human normal and bone-marrow stem cells, but not that of tumor cells, lead to the idea of improving stem cell therapies via low-dose radiation. Therefore, the aim of this study was to investigate unwanted side effects, as well as proliferation-stimulating mechanisms of LD-IR on ADSCs. (2) Methods: To avoid donor specific effects, ADSCs isolated from mamma reductions of 10 donors were pooled and used for the radiobiological analysis. The clonogenic survival assay was used to classify the long-term effects of low-dose radiation in ADSCs. Afterwards, cytotoxicity and genotoxicity, as well as the effect of irradiation on proliferation of ADSCs were investigated. (3) Results: LD (≤ 0.1 Gy) of ionizing radiation promoted the proliferation and survival of ADSCs. Within this dose range neither geno- nor cytotoxic effects were detectable. In contrast, greater doses within the dose range of >0.1–2.0 Gy induced residual double-strand breaks and reduced the long-term survival, as well as the proliferation rate of ADSCs. (4) Conclusions: Our data suggest that ADSCs are resistant to LD-IR. Furthermore, LD-IR could be a possible mediator to improve approaches of stem cells in the field of regenerative medicine.
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Berthel E, Foray N, Ferlazzo ML. The Nucleoshuttling of the ATM Protein: A Unified Model to Describe the Individual Response to High- and Low-Dose of Radiation? Cancers (Basel) 2019; 11:cancers11070905. [PMID: 31261657 PMCID: PMC6678722 DOI: 10.3390/cancers11070905] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Revised: 06/22/2019] [Accepted: 06/25/2019] [Indexed: 11/24/2022] Open
Abstract
The evaluation of radiation-induced (RI) risks is of medical, scientific, and societal interest. However, despite considerable efforts, there is neither consensual mechanistic models nor predictive assays for describing the three major RI effects, namely radiosensitivity, radiosusceptibility, and radiodegeneration. Interestingly, the ataxia telangiectasia mutated (ATM) protein is a major stress response factor involved in the DNA repair and signaling that appears upstream most of pathways involved in the three precited RI effects. The rate of the RI ATM nucleoshuttling (RIANS) was shown to be a good predictor of radiosensitivity. In the frame of the RIANS model, irradiation triggers the monomerization of cytoplasmic ATM dimers, which allows ATM monomers to diffuse in nucleus. The nuclear ATM monomers phosphorylate the H2AX histones, which triggers the recognition of DNA double-strand breaks and their repair. The RIANS model has made it possible to define three subgroups of radiosensitivity and provided a relevant explanation for the radiosensitivity observed in syndromes caused by mutated cytoplasmic proteins. Interestingly, hyper-radiosensitivity to a low dose and adaptive response phenomena may be also explained by the RIANS model. In this review, the relevance of the RIANS model to describe several features of the individual response to radiation was discussed.
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Affiliation(s)
- Elise Berthel
- Institut National de la Santé et de la Recherche Médicale, UA8, Radiations: Defense, Health and Environment, Centre Léon-Bérard, 28, rue Laennec, 69008 Lyon, France
| | - Nicolas Foray
- Institut National de la Santé et de la Recherche Médicale, UA8, Radiations: Defense, Health and Environment, Centre Léon-Bérard, 28, rue Laennec, 69008 Lyon, France.
| | - Mélanie L Ferlazzo
- Institut National de la Santé et de la Recherche Médicale, UA8, Radiations: Defense, Health and Environment, Centre Léon-Bérard, 28, rue Laennec, 69008 Lyon, France
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Mothersill C, Abend M, Bréchignac F, Copplestone D, Geras'kin S, Goodman J, Horemans N, Jeggo P, McBride W, Mousseau TA, O'Hare A, Papineni RVL, Powathil G, Schofield PN, Seymour C, Sutcliffe J, Austin B. The tubercular badger and the uncertain curve:- The need for a multiple stressor approach in environmental radiation protection. ENVIRONMENTAL RESEARCH 2019; 168:130-140. [PMID: 30296640 DOI: 10.1016/j.envres.2018.09.031] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 09/23/2018] [Accepted: 09/24/2018] [Indexed: 06/08/2023]
Abstract
This article presents the results of a workshop held in Stirling, Scotland in June 2018, called to examine critically the effects of low-dose ionising radiation on the ecosphere. The meeting brought together participants from the fields of low- and high-dose radiobiology and those working in radioecology to discuss the effects that low doses of radiation have on non-human biota. In particular, the shape of the low-dose response relationship and the extent to which the effects of low-dose and chronic exposure may be predicted from high dose rate exposures were discussed. It was concluded that high dose effects were not predictive of low dose effects. It followed that the tools presently available were deemed insufficient to reliably predict risk of low dose exposures in ecosystems. The workshop participants agreed on three major recommendations for a path forward. First, as treating radiation as a single or unique stressor was considered insufficient, the development of a multidisciplinary approach is suggested to address key concerns about multiple stressors in the ecosphere. Second, agreed definitions are needed to deal with the multiplicity of factors determining outcome to low dose exposures as a term can have different meanings in different disciplines. Third, appropriate tools need to be developed to deal with the different time, space and organisation level scales. These recommendations permit a more accurate picture of prospective risks.
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Affiliation(s)
- Carmel Mothersill
- Department of Biology, McMaster University, Hamilton, Ontario, Canada L8S 4K1.
| | - Michael Abend
- Bundeswehr Institute of Radiobiology, Neuherbergstrasse 11, 80937 Munich, Germany.
| | - Francois Bréchignac
- Institute for Radioprotection and Nuclear Safety (IRSN) & International Union of Radioecology, Centre du Cadarache, Bldg 229, St Paul-lez-Durance, France.
| | - David Copplestone
- Faculty of Natural Sciences, University of Stirling, Stirling FK9 4LA, Scotland, UK.
| | - Stanislav Geras'kin
- Russian Institute of Radiology & Agroecology, Kievskoe shosse, 109km, Obninsk 249020, Russia.
| | - Jessica Goodman
- Faculty of Natural Sciences, University of Stirling, Stirling FK9 4LA, Scotland, UK.
| | - Nele Horemans
- Belgian Nuclear Research Centre SCK CEN, Biosphere Impact Studies, Boeretang 200, B-2400 Mol, Belgium.
| | - Penny Jeggo
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton BN1 9RQ, UK.
| | - William McBride
- University of California Los Angeles, David Geffen School of Medicine, Department of Radiation Oncology, 10833 Le Conte Avenue, Los Angeles, CA 90095, USA.
| | - Timothy A Mousseau
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA.
| | - Anthony O'Hare
- Faculty of Natural Sciences, University of Stirling, Stirling FK9 4LA, Scotland, UK.
| | - Rao V L Papineni
- Department of Surgery, University of Kansas Medical Center - KUMC (Adjunct), and PACT & Health, Branford, CT, USA.
| | - Gibin Powathil
- Department of Mathematics, College of Science, Swansea University, Singleton Park, Swansea, Wales SA2 8PP, UK.
| | - Paul N Schofield
- Dept of Physiology Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK.
| | - Colin Seymour
- Department of Biology, McMaster University, Hamilton, Ontario, Canada L8S 4K1.
| | - Jill Sutcliffe
- Low Level Radiation and Health Conference, Ingrams Farm Fittleworth Road, Wisborough Green RH14 0JA, West Sussex, UK.
| | - Brian Austin
- Institute of Aquaculture, University of Stirling, Stirling FK9 4LA, Scotland, UK.
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Rusin A, Lapied E, Le M, Seymour C, Oughton D, Haanes H, Mothersill C. Effect of gamma radiation on the production of bystander signals from three earthworm species irradiated in vivo. ENVIRONMENTAL RESEARCH 2019; 168:211-221. [PMID: 30317106 DOI: 10.1016/j.envres.2018.09.023] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 09/03/2018] [Accepted: 09/19/2018] [Indexed: 06/08/2023]
Abstract
The effect of gamma radiation delivered over 24 h on the induction of bystander signals of three earthworm species exposed in vivo was investigated: A. chlorotica, A. caliginosa, and E. tetraedra. Worms were exposed to external gamma irradiation (Co-60 source) for 24 h and samples of head, body, and clitellum were dissected from exposed and control worms and placed in culture medium for 24 h at 19 C. The harvested medium was filtered and assayed for expression of bystander signals using both clonogenic and mitochondrial reporter assays. Different responses were observed in the different species and in the different tissues. A. chlorotica worm-treated reporters show insignificant mitochondrial response for all sections, yet a significant clonogenic reduction in survival for body sections. A. caliginosa worm-treated reporters show a significant mitochondrial response for some sections and insignificant mitochondrial response and insignificant reduction in clonogenic survival for the rest. E. tetraedra worms from a control site show significant evidence of bystander signalling, measured by mitochondrial response in reporter cells, for all sections while those harvested from a contaminated site show insignificant changes in baseline signalling when exposed to the challenge dose. In vivo exposure of earthworm species shows evidence of bystander signalling using two different reporter assays. This effect varied between the different species and tissues. There is also evidence of attenuated bystander signalling in worms harvested from a site contaminated with radiation.
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Affiliation(s)
- Andrej Rusin
- Dept. of Biology, McMaster University, Hamilton, ON, Canada.
| | - Emmanuel Lapied
- Centre for Environmental Radioactivity (CERAD), Norwegian University of Life Sciences, PO Box 5003, 1430 Aas, Norway
| | - Michelle Le
- Dept. of Biology, McMaster University, Hamilton, ON, Canada
| | - Colin Seymour
- Dept. of Biology, McMaster University, Hamilton, ON, Canada
| | - Deborah Oughton
- Centre for Environmental Radioactivity (CERAD), Norwegian University of Life Sciences, PO Box 5003, 1430 Aas, Norway
| | - Hallvard Haanes
- Centre for Environmental Radioactivity (CERAD), Norwegian University of Life Sciences, PO Box 5003, 1430 Aas, Norway; Norwegian Radiation Protection Authority (NRPA), Østerås, Norway
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Stewart RD, Carlson DJ, Butkus MP, Hawkins R, Friedrich T, Scholz M. A comparison of mechanism-inspired models for particle relative biological effectiveness (RBE). Med Phys 2018; 45:e925-e952. [PMID: 30421808 DOI: 10.1002/mp.13207] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 09/05/2018] [Accepted: 09/13/2018] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND AND SIGNIFICANCE The application of heavy ion beams in cancer therapy must account for the increasing relative biological effectiveness (RBE) with increasing penetration depth when determining dose prescriptions and organ at risk (OAR) constraints in treatment planning. Because RBE depends in a complex manner on factors such as the ion type, energy, cell and tissue radiosensitivity, physical dose, biological endpoint, and position within and outside treatment fields, biophysical models reflecting these dependencies are required for the personalization and optimization of treatment plans. AIM To review and compare three mechanism-inspired models which predict the complexities of particle RBE for various ion types, energies, linear energy transfer (LET) values and tissue radiation sensitivities. METHODS The review of models and mechanisms focuses on the Local Effect Model (LEM), the Microdosimetric-Kinetic (MK) model, and the Repair-Misrepair-Fixation (RMF) model in combination with the Monte Carlo Damage Simulation (MCDS). These models relate the induction of potentially lethal double strand breaks (DSBs) to the subsequent interactions and biological processing of DSB into more lethal forms of damage. A key element to explain the increased biological effectiveness of high LET ions compared to MV x rays is the characterization of the number and local complexity (clustering) of the initial DSB produced within a cell. For high LET ions, the spatial density of DSB induction along an ion's trajectory is much greater than along the path of a low LET electron, such as the secondary electrons produced by the megavoltage (MV) x rays used in conventional radiation therapy. The main aspects of the three models are introduced and the conceptual similarities and differences are critiqued and highlighted. Model predictions are compared in terms of the RBE for DSB induction and for reproductive cell survival. RESULTS AND CONCLUSIONS Comparisons of the RBE for DSB induction and for cell survival are presented for proton (1 H), helium (4 He), and carbon (12 C) ions for the therapeutically most relevant range of ion beam energies. The reviewed models embody mechanisms of action acting over the spatial scales underlying the biological processing of potentially lethal DSB into more lethal forms of damage. Differences among the number and types of input parameters, relevant biological targets, and the computational approaches among the LEM, MK and RMF models are summarized and critiqued. Potential experiments to test some of the seemingly contradictory aspects of the models are discussed.
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Affiliation(s)
- Robert D Stewart
- Department of Radiation Oncology, University of Washington School of Medicine, 1959 NE Pacific Street, Box 356043, Seattle, WA, 98195, USA
| | - David J Carlson
- Department of Therapeutic Radiology, Yale University, New Haven, CT, USA
| | - Michael P Butkus
- Department of Therapeutic Radiology, Yale University, New Haven, CT, USA
| | - Roland Hawkins
- Radiation Oncology Center, Ochsner Clinic Foundation, New Orleans, LA, 70121, USA
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Velegzhaninov IO, Ermakova AV, Klokov DY. Low dose ionizing irradiation suppresses cellular senescence in normal human fibroblasts. Int J Radiat Biol 2018; 94:825-828. [PMID: 29952691 DOI: 10.1080/09553002.2018.1492167] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
PURPOSE Exposure to high dose ionizing radiation leads to premature cell senescence and suppression of cell proliferation. In contrast, low dose and low dose-rate gamma-irradiation can lead to stimulation of cell proliferation. We aimed to examine whether the low dose radiation-induced proliferation of normal human fibroblasts can lead to a progressive depletion of proliferation potential and to an early onset of senescence. MATERIALS AND METHODS Normal human embryonic lung fibroblasts (HELF-104) at passage 22-24 were gamma-irradiated with doses of 0 (sham-irradiation), 10, 30, 50, 90, 120, 150, 200, and 500 mGy as well as 1 and 2 Gy. After irradiation, the fraction of cells positively stained for senescence-associated β-galactosidase activity was measured weekly until the cell culture completely ceased to proliferate. RESULTS We show that single irradiation of HELF-104 cells with 30 and 50 mGy resulted in deceleration of senescence. The suppression of senescence was observed during almost the entire length of the study up to a complete arrest of cell growth. CONCLUSIONS Our data, together with the previously published observation of delayed stimulation of proliferation in HELF-104 cells exposed to 30 mGy, suggest that low dose gamma-irradiation can increase the overall proliferative potential of normal human fibroblasts.
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Affiliation(s)
- Ilya O Velegzhaninov
- a Department of Radioecology , Institute of Biology of Komi Science Centre of Ural Branch of RAS , Syctyvkar , Russia.,b Polytechnical Institute, Vyatka State University , Kirov , Russia
| | - Anastasia V Ermakova
- a Department of Radioecology , Institute of Biology of Komi Science Centre of Ural Branch of RAS , Syctyvkar , Russia
| | - Dmitry Yu Klokov
- c Radiobiology and Health, Canadian Nuclear Laboratories , Chalk River , Canada.,d Department of Biochemistry, Microbiology and Immunology , University of Ottawa , Ottawa , Canada
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Devic C, Ferlazzo ML, Foray N. Influence of Individual Radiosensitivity on the Adaptive Response Phenomenon: Toward a Mechanistic Explanation Based on the Nucleo-Shuttling of ATM Protein. Dose Response 2018; 16:1559325818789836. [PMID: 30093841 PMCID: PMC6081762 DOI: 10.1177/1559325818789836] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 05/29/2018] [Accepted: 06/12/2018] [Indexed: 02/03/2023] Open
Abstract
The adaptive response (AR) phenomenon generally describes a protective effect caused by a "priming" low dose (dAR) delivered after a period of time (ΔtAR) before a higher "challenging" dose (DAR). The AR is currently observed in human cells if dAR, ΔtAR, and DAR belong to (0.001-0.5 Gy), (2-24 hours), (0.1-5 Gy), respectively. In order to investigate the molecular mechanisms specific to AR in human cells, we have systematically reviewed the experimental AR protocols, the cellular models, and the biological endpoints used from the 1980s. The AR appears to be preferentially observed in radiosensitive cells and is strongly dependent on individual radiosensitivity. To date, the model of the nucleo-shuttling of the ATM protein provides a relevant mechanistic explanation of the AR molecular and cellular events. Indeed, the priming dose dAR may result in the diffusion of a significant amount of active ATM monomers in the nucleus. These ATM monomers, added to those induced directly by the challenging dose DAR, may increase the efficiency of the response to DAR by a better ATM-dependent DNA damage recognition. Such mechanistic model would also explain why AR is not observed in radioresistant or hyperradiosensitive cells. Further investigations at low dose are needed to consolidate our hypotheses.
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Affiliation(s)
- Clément Devic
- Institut National de la Santé et de la Recherche Médicale (INSERM), Lyon, France.,Fibermetrix Company, Strasbourg, France
| | - Mélanie L Ferlazzo
- Institut National de la Santé et de la Recherche Médicale (INSERM), Lyon, France
| | - Nicolas Foray
- Institut National de la Santé et de la Recherche Médicale (INSERM), Lyon, France
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Relative Biological Effectiveness Uncertainties and Implications for Beam Arrangements and Dose Constraints in Proton Therapy. Semin Radiat Oncol 2018; 28:256-263. [DOI: 10.1016/j.semradonc.2018.02.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Differential miRNA expression profiling reveals miR-205-3p to be a potential radiosensitizer for low- dose ionizing radiation in DLD-1 cells. Oncotarget 2018; 9:26387-26405. [PMID: 29899866 PMCID: PMC5995186 DOI: 10.18632/oncotarget.25405] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Accepted: 04/28/2018] [Indexed: 12/12/2022] Open
Abstract
Enhanced radiosensitivity at low doses of ionizing radiation (IR) (0.2 to 0.6 Gy) has been reported in several cell lines. This phenomenon, known as low doses hyper-radiosensitivity (LDHRS), appears as an opportunity to decrease toxicity of radiotherapy and to enhance the effects of chemotherapy. However, the effect of low single doses IR on cell death is subtle and the mechanism underlying LDHRS has not been clearly explained, limiting the utility of LDHRS for clinical applications. To understand the mechanisms responsible for cell death induced by low-dose IR, LDHRS was evaluated in DLD-1 human colorectal cancer cells and the expression of 80 microRNAs (miRNAs) was assessed by qPCR array. Our results show that DLD-1 cells display an early DNA damage response and apoptotic cell death when exposed to 0.6 Gy. miRNA expression profiling identified 3 over-expressed (miR-205-3p, miR-1 and miR-133b) and 2 down-regulated miRNAs (miR-122-5p, and miR-134-5p) upon exposure to 0.6 Gy. This miRNA profile differed from the one in cells exposed to high-dose IR (12 Gy), supporting a distinct low-dose radiation-induced cell death mechanism. Expression of a mimetic miR-205-3p, the most overexpressed miRNA in cells exposed to 0.6 Gy, induced apoptotic cell death and, more importantly, increased LDHRS in DLD-1 cells. Thus, we propose miR-205-3p as a potential radiosensitizer to low-dose IR.
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Matsuya Y, Sasaki K, Yoshii Y, Okuyama G, Date H. Integrated Modelling of Cell Responses after Irradiation for DNA-Targeted Effects and Non-Targeted Effects. Sci Rep 2018; 8:4849. [PMID: 29555939 PMCID: PMC5859303 DOI: 10.1038/s41598-018-23202-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 03/07/2018] [Indexed: 01/10/2023] Open
Abstract
Intercellular communication after ionizing radiation exposure, so-called non-targeted effects (NTEs), reduces cell survival. Here we describe an integrated cell-killing model considering NTEs and DNA damage along radiation particle tracks, known as DNA-targeted effects (TEs) based on repair kinetics of DNA damage. The proposed model was applied to a series of experimental data, i.e., signal concentration, DNA damage kinetics, cell survival curve and medium transfer bystander effects (MTBEs). To reproduce the experimental data, the model considers the following assumptions: (i) the linear-quadratic (LQ) function as absorbed dose to express the hit probability to emit cell-killing signals, (ii) the potentially repair of DNA lesions induced by NTEs, and (iii) lower efficiency of repair for the damage in NTEs than that in TEs. By comparing the model results with experimental data, we found that signal-induced DNA damage and lower repair efficiency in non-hit cells are responsible for NTE-related repair kinetics of DNA damage, cell survival curve with low-dose hyper-radiosensitivity (HRS) and MTBEs. From the standpoint of modelling, the integrated cell-killing model with the LQ relation and a different repair function for NTEs provide a reasonable signal-emission probability and a new estimation of low-dose HRS linked to DNA repair efficiency.
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Affiliation(s)
- Yusuke Matsuya
- Graduate School of Health Sciences, Hokkaido University, Kita-12, Nishi-5, Kita-ku, Sapporo, 060-0812, Japan
| | - Kohei Sasaki
- Faculty of Health Sciences, Hokkaido University of Science, Maeda 7-15, Teine-ku, Sapporo, 006-8585, Japan
| | - Yuji Yoshii
- Biological Research, Education and Instrumentation Center, Sapporo Medical University, Minami-1, Nichi-17, Chuo-ku, Sapporo, 060-8556, Japan
| | - Go Okuyama
- Faculty of Health Sciences, Hokkaido University of Science, Maeda 7-15, Teine-ku, Sapporo, 006-8585, Japan
| | - Hiroyuki Date
- Faculty of Health Sciences, Hokkaido University, Kita-12, Nishi-5, Kita-ku, Sapporo, 060-0812, Japan.
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Tubin S, Ahmed MM, Gupta S. Radiation and hypoxia-induced non-targeted effects in normoxic and hypoxic conditions in human lung cancer cells. Int J Radiat Biol 2018; 94:199-211. [PMID: 29293036 DOI: 10.1080/09553002.2018.1422085] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
PURPOSE Many cell lines with anaerobic metabolism do not show cytotoxic abscopal effect (AE) following irradiation. Further, there is no existing data on the radiation- and hypoxia (H)-induced AE. The purpose of this study was to investigate and compare the status of radiation-induced abscopal effect (RIAE) in normoxic and hypoxic conditions. METHODS Lung cancer cells (A549, H460) were exposed either to hypoxia or normoxia and then irradiated (2 or 10 Gy). After 24 h, unirradiated hypoxic (H-CM) or normoxic (N-CM) conditioned media (CM) and irradiated hypoxic (H-RCM) or normoxic (N-RCM) CM was collected. Hypoxia-resistant clones (HR: A549/HR, H460/HR) were generated by continuous exposure of the cells to hypoxia. Unirradiated parental cells or HR were exposed to H-CM, N-CM, H-RCM or N-RCM. In some groups, 24 h after exposure to CM, cells were directly irradiated with 2 Gy. Cell growth was monitored using real-time cell electronic sensing system. Further, levels of hypoxia and HIF1α regulated angiogenesis related growth factors, basic fibroblast growth factor (bFGF), placental growth factor (PlGF), soluble fms-like tyrosine kinase (sFlt-1) and vascular endothelial growth factor (VEGF) were assessed in CM. RESULTS In the radio-resistant A549 cells, H-RCM was much more effective in inducing growth delay compared to N-RCM. In the radio-sensitive H460 cells, both N-RCM and H-RCM induced growth delay. Interestingly, effects of N-RCM were completely reversed in HR cells. Exposure of cells to direct irradiation (2 Gy) 24 h after incubation with CM resulted in 50-60% reduction in cell proliferation in A549/HR cells and a very significant induction of death (>95%) in H460/HR cells. Direct irradiation of parental or HR clones of A549 and H460 cells exposed to H-CM 24 h with 2 Gy induced significant reduction in cell proliferation (from 40% to >95%) in all the cells. Further, levels of sFlt-1 correlated with growth delay in all the cells. CONCLUSIONS These results for the first time demonstrate that irradiation of hypoxic cells and exposing the cells to acute hypoxia lead to significant AE.
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Affiliation(s)
- Slavisa Tubin
- a Department of Radiation Oncology , Sylvester Comprehensive Cancer Center, University of Miami Leonard Miller School of Medicine , Miami , FL , USA
| | - Mansoor M Ahmed
- b Division of Cancer Treatment and Diagnosis , National Cancer Institute, National Institutes of Health, Radiotherapy Development Branch, Radiation Research Program , Rockville , MD , USA
| | - Seema Gupta
- a Department of Radiation Oncology , Sylvester Comprehensive Cancer Center, University of Miami Leonard Miller School of Medicine , Miami , FL , USA
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Hofer T, Duale N, Muusse M, Eide DM, Dahl H, Boix F, Andersen JM, Olsen AK, Myhre O. Restoration of Cognitive Performance in Mice Carrying a Deficient Allele of 8-Oxoguanine DNA Glycosylase by X-ray Irradiation. Neurotox Res 2017; 33:824-836. [DOI: 10.1007/s12640-017-9833-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 10/13/2017] [Accepted: 10/18/2017] [Indexed: 12/13/2022]
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Terashima S, Hosokawa Y, Tsuruga E, Mariya Y, Nakamura T. Impact of time interval and dose rate on cell survival following low-dose fractionated exposures. JOURNAL OF RADIATION RESEARCH 2017; 58:782-790. [PMID: 28595296 PMCID: PMC5710595 DOI: 10.1093/jrr/rrx025] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 03/08/2017] [Indexed: 05/23/2023]
Abstract
Enhanced cell lethality, also known as hyper-radiosensitivity, has been reported at low doses of radiation (≤0.5 Gy) in various cell lines, and is expected to be an effective cancer therapy. We conducted this study to examine the impact of time interval and dose rate of low-dose fractionated exposures with a short time interval. We evaluated the cell-survival rates of V79 and A549 cells using clonogenic assays. We performed fractionated exposures in unit doses of 0.25, 0.5, 1.0 and 2.0 Gy. We exposed the cells to 2 Gy of X-rays (i) at dose-rates of 1.0, 1.5 and 2.0 Gy/min at 1-min intervals and (ii) at a dose-rate of 2.0 Gy/min at 10-s, 1-min and 3-min intervals by fractionated exposures. Apoptosis and cell cycle analyses were also evaluated in the fractionated exposures (unit dose 0.25 Gy) and compared with single exposures by using flow cytometry. Both cell-type survival rates with fractionated exposures (unit dose 0.25 Gy) with short time intervals were markedly lower than those for single exposures delivering the same dose. When the dose rates were lower, the cytotoxic effect decreased compared with exposure to a dose-rate of 2.0 Gy/min. On the other hand, levels of apoptosis and cell cycle distribution were not significantly different between low-dose fractionated exposures and single exposures in either cell line. These results indicate that a stronger cytotoxic effect was induced with low-dose fractionated exposures with a short time interval for a given dose due to the hyper-radiosensitivity phenomenon, suggesting that dose rates are important for effective low-dose fractionated exposures.
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Affiliation(s)
- Shingo Terashima
- Department of Radiation Science, Hirosaki University Graduate School of Health Sciences, 66-1 Hon-cho, Hirosaki, Aomori 036-8564, Japan
| | - Yoichiro Hosokawa
- Department of Radiation Science, Hirosaki University Graduate School of Health Sciences, 66-1 Hon-cho, Hirosaki, Aomori 036-8564, Japan
| | - Eichi Tsuruga
- Department of Radiation Science, Hirosaki University Graduate School of Health Sciences, 66-1 Hon-cho, Hirosaki, Aomori 036-8564, Japan
| | - Yasushi Mariya
- Department of Radiology, Mutsu General Hospital, 1-2-8 Kogawa-cho, Mutsu, Aomori 035-8601, Japan
| | - Toshiya Nakamura
- Department of Bioscience and Laboratory Medicine, Hirosaki University Graduate School of Health Sciences, 66-1 Hon-cho, Hirosaki, Aomori 036-8564, Japan
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Tharmalingam S, Sreetharan S, Kulesza AV, Boreham DR, Tai TC. Low-Dose Ionizing Radiation Exposure, Oxidative Stress and Epigenetic Programing of Health and Disease. Radiat Res 2017; 188:525-538. [PMID: 28753061 DOI: 10.1667/rr14587.1] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Ionizing radiation exposure from medical diagnostic imaging has greatly increased over the last few decades. Approximately 80% of patients who undergo medical imaging are exposed to low-dose ionizing radiation (LDIR). Although there is widespread consensus regarding the harmful effects of high doses of radiation, the biological effects of low-linear energy transfer (LET) LDIR is not well understood. LDIR is known to promote oxidative stress, however, these levels may not be large enough to result in genomic mutations. There is emerging evidence that oxidative stress causes heritable modifications via epigenetic mechanisms (DNA methylation, histone modification, noncoding RNA regulation). These epigenetic modifications result in permanent cellular transformations without altering the underlying DNA nucleotide sequence. This review summarizes the major concepts in the field of epigenetics with a focus on the effects of low-LET LDIR (<100 mGy) and oxidative stress on epigenetic gene modification. In this review, we show evidence that suggests that LDIR-induced oxidative stress provides a mechanistic link between LDIR and epigenetic gene regulation. We also discuss the potential implication of LDIR exposure during pregnancy where intrauterine fetal development is highly susceptible to oxidative stress-induced epigenetic programing.
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Affiliation(s)
| | | | - Adomas V Kulesza
- b Department of Biology, McMaster University, Hamilton, Canada, L8S 4K1
| | - Douglas R Boreham
- a Northern Ontario School of Medicine, Laurentian University, Sudbury, Canada, P3E 2C6.,c Department of Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, Canada, L8S 4K1
| | - T C Tai
- a Northern Ontario School of Medicine, Laurentian University, Sudbury, Canada, P3E 2C6
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Bolsunovsky A, Frolova T, Dementyev D, Sinitsyna O. Low doses of gamma-radiation induce SOS response and increase mutation frequency in Escherichia coli and Salmonella typhimurium cells. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2016; 134P1:233-238. [PMID: 27639198 DOI: 10.1016/j.ecoenv.2016.09.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2016] [Revised: 08/22/2016] [Accepted: 09/07/2016] [Indexed: 06/06/2023]
Abstract
This study addresses use of two bacterial test systems (the Ames test and the SOS chromotest) to estimate the effects of low doses of γ-radiation. The most substantial increases in induction of SOS response and mutation frequencies were observed in the first 24h of exposure to γ-radiation as compared to the cells in the exposure-free control. Gamma-radiation also impaired growth and survival of S. typhimurium cells in the first 24h. The effects were attenuated at lower exposure doses and at longer exposure times. In the experiments conducted in this study, at 96h of exposure, the values of some of the γ-radiation effects were lower than the MID (minimum inducing dose) detection limits and, thus, were neglected. Long-term exposure to γ-radiation could also result in combined effects of γ-radiation and the death of cells in the culture.
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Affiliation(s)
- Alexander Bolsunovsky
- Institute of Biophysics of the Siberian Branch of the Russian Academy of Sciences, Krasnoyarsk, Russia.
| | - Tatiana Frolova
- FRC Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia; Novosibirsk State University, Novosibirsk, Russia
| | - Dmitry Dementyev
- Institute of Biophysics of the Siberian Branch of the Russian Academy of Sciences, Krasnoyarsk, Russia
| | - Olga Sinitsyna
- FRC Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia; Novosibirsk State University, Novosibirsk, Russia
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Shi X, Seymour C, Mothersill C. The effects of chronic, low doses of Ra-226 on cultured fish and human cells. ENVIRONMENTAL RESEARCH 2016; 148:303-309. [PMID: 27093471 DOI: 10.1016/j.envres.2016.04.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Revised: 04/05/2016] [Accepted: 04/07/2016] [Indexed: 06/05/2023]
Abstract
PURPOSE To determine the chronic low-dose radiation effects caused by α-particle radiation from (226)Ra over multiple cell generations in CHSE/F fish cells and HaCaT human cells. METHODS CHSE/F cells and HaCaT cells were cultured in medium containing (226)Ra to deliver the chronic low-dose α-particle radiation. Clonogenic assay was used to test the clonogenic survival fractions of cells with or without being exposed to radiation from (226)Ra. RESULTS The chronic low-dose radiation from (226)Ra does have effects on the clonogenic survival of CHSE/F cells and HaCaT cells. When CHSE/F cells were cultured in (226)Ra-medium over 9 passages for about 134 days, the clonogenic surviving fractions for cells irradiated at dose rates ranging from 0.00066 to 0.66mGy/d were significantly lower than that of cells sham irradiated. For HaCaT cells grown in medium containing the same range of (226)Ra activity, the clonogenic surviving fraction decreased at first and reached the lowest value at about 42 days (8 passages). After that, the clonogenic survival began to increase, and was significantly higher than that of control cells by the end of the experimental period. CONCLUSION The chronic, low-dose high LET radiation from (226)Ra can influence the clonogenic survival of irradiated cells. CHSE/F cells were sensitized by the radiation, and HaCaT cells were initially sensitized but later appeared to be adapted. The results could have implications for determining risk from chronic versus acute exposures to radium.
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Affiliation(s)
- Xiaopei Shi
- Medical Physics and Applied Radiation Sciences, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4L8, Canada
| | - Colin Seymour
- Medical Physics and Applied Radiation Sciences, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4L8, Canada
| | - Carmel Mothersill
- Medical Physics and Applied Radiation Sciences, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4L8, Canada.
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Al-Ta’ii HMJ, Amin YM, Periasamy V. Humidity influenced capacitance and resistance of an Al/DNA/Al Schottky diode irradiated by alpha particles. Sci Rep 2016; 6:25519. [PMID: 27160654 PMCID: PMC4861926 DOI: 10.1038/srep25519] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 04/15/2016] [Indexed: 11/10/2022] Open
Abstract
Deoxyribonucleic acid or DNA based sensors, especially as humidity and alpha particle sensors have become quite popular in recent times due to flexible and highly optimizable nature of this fundamental biomaterial. Application of DNA electronics allow for more sensitive, accurate and effective sensors to be developed and fabricated. In this work, we examined the effect of different humidity conditions on the capacitive and resistive response of Aluminum (Al)/DNA/Al Schottky barrier structure when bombarded by time-dependent dosages of alpha particles. Based on current-voltage profiles, which demonstrated rectifying behaviours, Schottky diode parameters such as ideality factor, barrier height and series resistance was calculated. Results observed generally pointed towards a decrease in the resistance value from the pristine to the radiated structures. It was also demonstrated that under the effect of humidity, the capacitance of the DNA thin film increased from 0.05894 to 92.736 nF, with rising relative humidity level. We also observed the occurrence of the hypersensitivity phenomena after alpha irradiation between 2 to 4 min by observing a drop in the series resistance, crucial in the study of DNA damage and repair mechanisms. These observations may also suggest the exciting possibility of utilizing Al/DNA/Al Schottky diodes as potentially sensitive humidity sensors.
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Affiliation(s)
- Hassan Maktuff Jaber Al-Ta’ii
- Low Dimensional Materials Research Centre (LDMRC), Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia
- Department of Physics, Faculty of Science, University of Al-Muthanna, 66001, Iraq
| | - Yusoff Mohd Amin
- Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Vengadesh Periasamy
- Low Dimensional Materials Research Centre (LDMRC), Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia
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Bogen KT. Linear-No-Threshold Default Assumptions for Noncancer and Nongenotoxic Cancer Risks: A Mathematical and Biological Critique. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2016; 36:589-604. [PMID: 26249816 DOI: 10.1111/risa.12460] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
To improve U.S. Environmental Protection Agency (EPA) dose-response (DR) assessments for noncarcinogens and for nonlinear mode of action (MOA) carcinogens, the 2009 NRC Science and Decisions Panel recommended that the adjustment-factor approach traditionally applied to these endpoints should be replaced by a new default assumption that both endpoints have linear-no-threshold (LNT) population-wide DR relationships. The panel claimed this new approach is warranted because population DR is LNT when any new dose adds to a background dose that explains background levels of risk, and/or when there is substantial interindividual heterogeneity in susceptibility in the exposed human population. Mathematically, however, the first claim is either false or effectively meaningless and the second claim is false. Any dose-and population-response relationship that is statistically consistent with an LNT relationship may instead be an additive mixture of just two quasi-threshold DR relationships, which jointly exhibit low-dose S-shaped, quasi-threshold nonlinearity just below the lower end of the observed "linear" dose range. In this case, LNT extrapolation would necessarily overestimate increased risk by increasingly large relative magnitudes at diminishing values of above-background dose. The fact that chemically-induced apoptotic cell death occurs by unambiguously nonlinear, quasi-threshold DR mechanisms is apparent from recent data concerning this quintessential toxicity endpoint. The 2009 NRC Science and Decisions Panel claims and recommendations that default LNT assumptions be applied to DR assessment for noncarcinogens and nonlinear MOA carcinogens are therefore not justified either mathematically or biologically.
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Silver NL, Arnold SM, Gleason JF, Kudrimoti M, Brill Y, Dressler EV, Valentino J. p16INK4a Status and Response to Induction Low-Dose Fractionated Radiation in Advanced Head and Neck Cancer. Ann Otol Rhinol Laryngol 2015; 124:714-20. [PMID: 25810339 PMCID: PMC5555599 DOI: 10.1177/0003489415579220] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE To evaluate the impact of p16INK4a (p16) expression on clinical efficacy of induction low-dose fractionated radiation therapy (LDFRT) with concurrent chemotherapy in patients with locally advanced squamous cell carcinoma of the head and neck (SCCHN). STUDY DESIGN Historical cohort study. SETTING Tertiary medical center. METHODS A total of 66 Patients with locally advanced SCCHN were enrolled in 2 clinical trials using paclitaxel, carboplatin, and concurrent LDFRT induction therapy. Patients were evaluated for response to induction by a multidisciplinary team and then were given definitive treatment. Adequate tissue samples from the pretreatment biopsies of 42 individuals were identified and analyzed for p16 expression. Expression was correlated with clinical outcomes. RESULTS Of 42 tumors, 15 (35.7%) were positive for p16. Patients with p16-positive tumors had improved response to induction, but this was not statistically significant (P = .06). Five-year overall survival was 80% in p16-positive patients and 58% in p16-negative patients (P = .025). CONCLUSIONS p16 Expression affects treatment response in patients treated with induction LDFRT with concurrent chemotherapy. This is similar to results reported for standard induction chemotherapy.
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Affiliation(s)
- Natalie L Silver
- Department of Otolaryngology HNS, University of Kentucky College of Medicine, Lexington, Kentucky, USA
| | - Susanne M Arnold
- Division of Medical Oncology, University of Kentucky College of Medicine, Lexington, Kentucky, USA
| | - John F Gleason
- Department of Radiation, University of Kentucky College of Medicine, Lexington, Kentucky, USA
| | - Mahesh Kudrimoti
- Department of Radiation, University of Kentucky College of Medicine, Lexington, Kentucky, USA
| | - Yolanda Brill
- Department of Pathology, University of Kentucky College of Medicine, Lexington, Kentucky, USA
| | - Emily V Dressler
- Division of Cancer Biostatistics, University of Kentucky College of Public Health, Lexington, Kentucky, USA
| | - Joseph Valentino
- Department of Otolaryngology HNS, University of Kentucky College of Medicine, Lexington, Kentucky, USA
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Das S, Singh R, George D, Vijaykumar TS, John S. Radiobiological Response of Cervical Cancer Cell Line in Low Dose Region: Evidence of Low Dose Hypersensitivity (HRS) and Induced Radioresistance (IRR). J Clin Diagn Res 2015; 9:XC05-XC08. [PMID: 26266200 DOI: 10.7860/jcdr/2015/14120.6074] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2015] [Accepted: 05/07/2015] [Indexed: 11/24/2022]
Abstract
BACKGROUND Purpose of the present study was to examine the response of cervical cancer cell line (HeLa cell line) to low dose radiation using clonogenic assay and mathematical modeling of the low dose response by Joiner's induced repair model. MATERIALS AND METHODS Survival of HeLa cells following exposure to single and fractionated low doses of γ (gamma)-ray, 6 MV, and 15 MV photon was measured by clonogenic assay. RESULTS HeLa cell line demonstrated marked low dose response consisting of an area of HRS and IRR in the dose region of <1 Gy. The two gradients of the low dose region (αs and αr) were distinctly different with a transition dose (Dc) of 0.28-0.40 cGy. CONCLUSION HeLa cell line demonstrates marked HRS and IRR with distinct transition dose. This may form the biological basis of the clinical study to investigate the chemo potentiating effect of low dose radiation in cervical cancer.
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Affiliation(s)
- Saikat Das
- Associate Professor, Department of Radiation Oncology, Christian Medical College Vellore, India
| | - Rabiraja Singh
- Associate Professor, Department of Radiation Oncology, Christian Medical College Vellore, India
| | - Daicy George
- Medical Physics intern, Department of Radiation Oncology, Christian Medical College Vellore, India
| | - T S Vijaykumar
- Senior Scientist, Department of Nephrology, Christian Medical College Vellore, India
| | - Subhashini John
- Professor, Department of Radiation Oncology, Christian Medical College Vellore, India
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Joshi GS, Joiner MC, Tucker JD. Effects of low oxygen levels on G2-specific cytogenetic low-dose hyper-radiosensitivity in irradiated human cells. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2015; 56:545-555. [PMID: 25808121 DOI: 10.1002/em.21948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Revised: 02/28/2015] [Accepted: 03/02/2015] [Indexed: 06/04/2023]
Abstract
Low-dose hyper-radiosensitivity (HRS) has been reported in normal human lymphoblastoid cell lines for exposures at ≤ 20 cGy, but the cytogenetic effects of oxygen (O2 ) levels in tissue culture medium on HRS have not been evaluated. We asked whether HRS was lost in G2-irradiated cells grown in atmospheres of 2.5% or 5% O2 , compared to responses by cells cultured in ambient O2 (21%). The results indicate a loss of HRS when cells are cultured and irradiated either in 2.5% or 5% O2 . We then evaluated whether low O2 levels either before or after exposure were responsible for the loss of HRS. For cells irradiated in 5% O2 , subsequent immediate re-oxygenation to ambient O2 levels restored the HRS effect, while cells cultured and irradiated at ambient O2 levels and then transferred to 5% O2 exhibited little or no HRS, indicating that ambient O2 levels after, but not before, radiation substantially affect the amounts of cytogenetic damage. HRS was not observed when cells were irradiated in G1. At doses of 40-400 cGy there was significantly less cytogenetic damage when cells were recovering from radiation at low O2 levels than at ambient O2 levels. Here we provide the first cytogenetic evidence for the loss of HRS at low O2 levels in G2-irradiated cells; these results suggest that at low O2 levels for all doses evaluated there is either less damage to DNA, perhaps because of lower amounts of reactive oxygen species, or that DNA damage repair pathways are activated more efficiently.
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Affiliation(s)
- Gnanada S Joshi
- Department of Biological Sciences, Wayne State University, Detroit, Michigan
| | - Michael C Joiner
- Department of Radiation Oncology, Wayne State University, Detroit, Michigan
| | - James D Tucker
- Department of Biological Sciences, Wayne State University, Detroit, Michigan
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Edin NJ, Altaner Č, Altanerova V, Ebbesen P. TGF-B3 Dependent Modification of Radiosensitivity in Reporter Cells Exposed to Serum From Whole-Body Low Dose-Rate Irradiated Mice. Dose Response 2015; 13:10.2203_dose-response.14-015.Edin. [PMID: 26673923 PMCID: PMC4674161 DOI: 10.2203/dose-response.14-015.edin] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Prior findings in vitro of a TGF-β3 dependent mechanism induced by low dose-rate irradiation and resulting in increased radioresistance and removal of low dose hyper-radiosensitivity (HRS) was tested in an in vivo model. DBA/2 mice were given whole-body irradiation for 1 h at low dose-rates (LDR) of 0.3 or 0.03 Gy/h. Serum was harvested and added to RPMI (4% mouse serum and 6% bovine serum).This medium was transferred to reporter cells (T-47D breast cancer cells or T98G glioblastoma cells). The response to subsequent challenge irradiation of the reporter cells was measured by the colony assay. While serum from unirradiated control mice had no effect on the radiosensitivity in the reporter cells, serum from mice given 0.3 Gy/h or 0.03 Gy/h for 1 h removed HRS and also increased survival in response to doses up to 5 Gy. The effect lasted for at least 15 months after irradiation. TGF-β3 neutralizer added to the medium containing mouse serum inhibited the effect. Serum from mice given irradiation of 0.3 Gy/h for 1 h and subsequently treated with iNOS inhibitor 1400W did not affect radiosensitivity in reporter cells; neither did serum from the unirradiated progeny of mice given 1h LDR whole-body irradiation.
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Affiliation(s)
- Nina Jeppesen Edin
- Department of Physics, University of Oslo, 0316 Oslo, Norway ; Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, Montebello, 0310 Oslo, Norway
| | - Čestmír Altaner
- Cancer Research Institute, Slovak Academy of Sciences, Bratislava, Slovakia
| | | | - Peter Ebbesen
- Department of Physics, University of Oslo, 0316 Oslo, Norway ; Laboratory for Stem Cell Research, Aalborg University, Fredrik Bajers Vej 3B, 9220 Aalborg Ø. Denmark
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Kim JS, Kim SY, Lee M, Kim SH, Kim SM, Kim EJ. Radioresistance in a human laryngeal squamous cell carcinoma cell line is associated with DNA methylation changes and topoisomerase II α. Cancer Biol Ther 2015; 16:558-66. [PMID: 25719218 DOI: 10.1080/15384047.2015.1017154] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Accumulating evidence suggests that changes in methylation patterns may help mediate the sensitivity or resistance of cancer cells to ionizing radiation. The present study provides evidence for the involvement of radioresistance-induced DNA methylation changes in tumor radioresistance. We established radioresistant laryngeal cancer cells via long-term fractionated irradiation, and examined differences in DNA methylation between control and radioresistant laryngeal cancer cells. Interestingly, we found that the promoter-CpG islands of 5 previously identified radioresistance-related genes (TOPO2A, PLXDC2, ETNK2, GFI1, and IL12B) were significantly altered in the radioresistant laryngeal cancer cells. Furthermore, the demethylation of these gene promoters with a DNA methyltransferase inhibitor (5-aza-2'-deoxycytidine) increased their transcription levels. Treatment with 5-aza-2'-deoxycytidine also sensitized the radioresistant laryngeal cancer cells to irradiation, indicating that changes in DNA methylation contributed to their radioresistance. Of the tested genes, the expression and activity levels of TOPO2A were tightly associated with the radioresistant phenotype in our system, suggesting that the hypermethylation of TOPO2A might be involved in this radioresistance. Collectively, our data suggest that radiation-induced epigenetic changes can modulate the radioresistance of laryngeal cancer cells, and thus may prove useful as prognostic indicators for radiotherapy.
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Affiliation(s)
- Jae-Sung Kim
- a Division of Radiation Cancer Research; Korea Institute of Radiological & Medical Sciences ; Seoul , Korea
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Smith RW, Wang J, Mothersill CE, Lee LEJ, Seymour CB. Proteomic responses in the gills of fathead minnows (Pimephales promelas, Rafinesque, 1820) after 6 months and 2 years of continuous exposure to environmentally relevant dietary226Ra. Int J Radiat Biol 2015; 91:248-56. [DOI: 10.3109/09553002.2014.988894] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Joshi GS, Joiner MC, Tucker JD. Cytogenetic characterization of low-dose hyper-radiosensitivity in Cobalt-60 irradiated human lymphoblastoid cells. Mutat Res 2014; 770:69-78. [PMID: 25771872 DOI: 10.1016/j.mrfmmm.2014.09.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 09/06/2014] [Accepted: 09/16/2014] [Indexed: 06/04/2023]
Abstract
The dose-effect relationships of cells exposed to ionizing radiation are frequently described by linear quadratic (LQ) models over an extended dose range. However, many mammalian cell lines, when acutely irradiated in G2 at doses ≤0.3Gy, show hyper-radiosensitivity (HRS) as measured by reduced clonogenic cell survival, thereby indicating greater cell lethality than is predicted by extrapolation from high-dose responses. We therefore hypothesized that the cytogenetic response in G2 cells to low doses would also be steeper than predicted by LQ extrapolation from high doses. We tested our hypothesis by exposing four normal human lymphoblastoid cell lines to 0-400cGy of Cobalt-60 gamma radiation. The cytokinesis block micronucleus assay was used to determine the frequencies of micronuclei and nucleoplasmic bridges. To characterize the dependence of the cytogenetic damage on dose, univariate and multivariate regression analyses were used to compare the responses in the low- (HRS) and high-dose response regions. Our data indicate that the slope of the response for all four cell lines at ≤20cGy during G2 is greater than predicted by an LQ extrapolation from the high-dose responses for both micronuclei and bridges. These results suggest that the biological consequences of low-dose exposures could be underestimated and may not provide accurate risk assessments following such exposures.
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Affiliation(s)
- Gnanada S Joshi
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202, United States
| | - Michael C Joiner
- Department of Radiation Oncology, Wayne State University, Detroit, MI 48201, United States
| | - James D Tucker
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202, United States.
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Paganetti H. Relative biological effectiveness (RBE) values for proton beam therapy. Variations as a function of biological endpoint, dose, and linear energy transfer. Phys Med Biol 2014; 59:R419-72. [PMID: 25361443 DOI: 10.1088/0031-9155/59/22/r419] [Citation(s) in RCA: 601] [Impact Index Per Article: 60.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Proton therapy treatments are based on a proton RBE (relative biological effectiveness) relative to high-energy photons of 1.1. The use of this generic, spatially invariant RBE within tumors and normal tissues disregards the evidence that proton RBE varies with linear energy transfer (LET), physiological and biological factors, and clinical endpoint. Based on the available experimental data from published literature, this review analyzes relationships of RBE with dose, biological endpoint and physical properties of proton beams. The review distinguishes between endpoints relevant for tumor control probability and those potentially relevant for normal tissue complication. Numerous endpoints and experiments on sub-cellular damage and repair effects are discussed. Despite the large amount of data, considerable uncertainties in proton RBE values remain. As an average RBE for cell survival in the center of a typical spread-out Bragg peak (SOBP), the data support a value of ~1.15 at 2 Gy/fraction. The proton RBE increases with increasing LETd and thus with depth in an SOBP from ~1.1 in the entrance region, to ~1.15 in the center, ~1.35 at the distal edge and ~1.7 in the distal fall-off (when averaged over all cell lines, which may not be clinically representative). For small modulation widths the values could be increased. Furthermore, there is a trend of an increase in RBE as (α/β)x decreases. In most cases the RBE also increases with decreasing dose, specifically for systems with low (α/β)x. Data on RBE for endpoints other than clonogenic cell survival are too diverse to allow general statements other than that the RBE is, on average, in line with a value of ~1.1. This review can serve as a source for defining input parameters for applying or refining biophysical models and to identify endpoints where additional radiobiological data are needed in order to reduce the uncertainties to clinically acceptable levels.
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Affiliation(s)
- Harald Paganetti
- Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, 30 Fruit Street, Boston, MA 02114, USA
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Tang FR, Loke WK. Molecular mechanisms of low dose ionizing radiation-induced hormesis, adaptive responses, radioresistance, bystander effects, and genomic instability. Int J Radiat Biol 2014; 91:13-27. [DOI: 10.3109/09553002.2014.937510] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Belchior A, Balásházy I, Monteiro Gil O, Vaz P, Almeida P. Does the number of irradiated cells influence the spatial distribution of bystander effects? Dose Response 2014; 12:525-39. [PMID: 25552955 DOI: 10.2203/dose-response.14-001.belchior] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
There is growing evidence that the radiation effects at low doses are not adequately described by a simple linear extrapolation from high doses, due, among others, to bystander effects. Though several studies have been published on this topic, the explanation of the mechanisms describing the bystander effects remains unclear. This study aims at understanding how the bystander signals are or can be propagated in the cell culture, namely if the number of irradiated cells influences the bystander response. An A549 cell line was exposed to several doses of α-particles, being the bystander response quantified in two non-irradiated areas. The radius of irradiated areas differs by a factor of 2, and the non-irradiated areas were optimally designed to have the same number of cells. Our results show evidence for bystander effects occurring in cells far away from the irradiated ones, meaning that bystander signals can easily spread throughout the cell culture. Additionally, our study highlights that the damage caused by radiation on the surrounding of irradiated areas could be different according to the number of irradiated cells, i.e., for the same dose value; the overall cellular damage could be different.
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Affiliation(s)
- A Belchior
- IST/CTN, Instituto Superior Técnico, Universidade Técnica de Lisboa, Portugal and Universidade de Lisboa, Instituto de Biofísica e Engenharia Biomédica (IBEB), Portugal
| | - I Balásházy
- Envirionmental Physics Department, Hungarian Academy of Sciences Center for Energy Research, Hungary
| | - O Monteiro Gil
- IST/CTN, Instituto Superior Técnico, Universidade Técnica de Lisboa, Portugal
| | - P Vaz
- IST/CTN, Instituto Superior Técnico, Universidade Técnica de Lisboa, Portugal
| | - P Almeida
- Universidade de Lisboa, Instituto de Biofísica e Engenharia Biomédica (IBEB), Portugal
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Blimkie MSJ, Fung LCW, Petoukhov ES, Girard C, Klokov D. Repair of DNA double-strand breaks is not modulated by low-dose gamma radiation in C57BL/6J mice. Radiat Res 2014; 181:548-59. [PMID: 24785832 DOI: 10.1667/rr13324.1] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
In this study, we sought to determine whether low-dose ionizing radiation, previously shown to induce a systemic adaptive response in C57BL/6J mice, is capable of enhancing the rate of DNA double-strand break repair. Repair capacity was determined by measuring γ-H2AX levels in splenic and thymic lymphocytes, using flow cytometry, at different times after a challenge irradiation (2 Gy, (60)Co). Irradiation with low doses (20 and 100 mGy) was conducted in vivo, whereas the challenge dose was applied to primary cultures of splenocytes and thymocytes in vitro 24 h later. Obtained kinetics curves of formation and loss of γ-H2AX indicated that cells from low-dose irradiated mice did not express more efficient DNA double-strand break repair compared to controls. Immunoblot analysis of γ-H2AX and Phospho-Ser-1981 ATM confirmed that DNA damage signaling was not modulated by preliminary low-dose radiation. Mouse embryonic fibroblasts of C57BL genetic background failed to show clonogenic survival radioadaptive response or enhanced repair of DNA double-strand breaks as evaluated by immunofluorescence microscopy of γ-H2AX foci. Our results indicate that radiation adaptive responses at systemic levels, such as increases in the tumor latency times in aging mice, may not be mediated by modulated DNA repair, and that the genetic background may affect expression of a radioadaptive response.
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Affiliation(s)
- Melinda S J Blimkie
- a Chalk River Laboratories, Atomic Energy of Canada Limited, Chalk River, Ontario, Canada
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