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Chaurasia RK, Sapra BK, Aswal DK. Interplay of immune modulation, adaptive response and hormesis: Suggestive of threshold for clinical manifestation of effects of ionizing radiation at low doses? THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 917:170178. [PMID: 38280586 DOI: 10.1016/j.scitotenv.2024.170178] [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: 08/10/2023] [Revised: 12/26/2023] [Accepted: 01/13/2024] [Indexed: 01/29/2024]
Abstract
The health impacts of low-dose ionizing radiation exposures have been a subject of debate over the last three to four decades. While there has been enough evidence of "no adverse observable" health effects at low doses and low dose rates, the hypothesis of "Linear No Threshold" continues to rule and govern the principles of radiation protection and the formulation of regulations and public policies. In adopting this conservative approach, the role of the biological processes underway in the human body is kept at abeyance. This review consolidates the available studies that discuss all related biological pathways and repair mechanisms that inhibit the progression of deleterious effects at low doses and low dose rates of ionizing radiation. It is pertinent that, taking cognizance of these processes, there is a need to have a relook at policies of radiation protection, which as of now are too stringent, leading to undue economic losses and negative public perception about radiation.
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Affiliation(s)
- R K Chaurasia
- Radiological Physics and Advisory Division, India; Health, Safety and Environment Group,Bhabha Atomic Research Centre, Mumbai 400085, India; Homi Bhabha National Institute, Mumbai 400094, India.
| | - B K Sapra
- Radiological Physics and Advisory Division, India; Health, Safety and Environment Group,Bhabha Atomic Research Centre, Mumbai 400085, India; Homi Bhabha National Institute, Mumbai 400094, India.
| | - D K Aswal
- Health, Safety and Environment Group,Bhabha Atomic Research Centre, Mumbai 400085, India; Homi Bhabha National Institute, Mumbai 400094, India.
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Cui J, Yang G, Pan Z, Zhao Y, Liang X, Li W, Cai L. Hormetic Response to Low-Dose Radiation: Focus on the Immune System and Its Clinical Implications. Int J Mol Sci 2017; 18:ijms18020280. [PMID: 28134809 PMCID: PMC5343816 DOI: 10.3390/ijms18020280] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 01/17/2017] [Indexed: 12/12/2022] Open
Abstract
The interrelationship between ionizing radiation and the immune system is complex, multifactorial, and dependent on radiation dose/quality and immune cell type. High-dose radiation usually results in immune suppression. On the contrary, low-dose radiation (LDR) modulates a variety of immune responses that have exhibited the properties of immune hormesis. Although the underlying molecular mechanism is not fully understood yet, LDR has been used clinically for the treatment of autoimmune diseases and malignant tumors. These advancements in preclinical and clinical studies suggest that LDR-mediated immune modulation is a well-orchestrated phenomenon with clinical potential. We summarize recent developments in the understanding of LDR-mediated immune modulation, with an emphasis on its potential clinical applications.
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Affiliation(s)
- Jiuwei Cui
- Cancer Center, the First Hospital of Jilin University, Changchun 130021, China.
| | - Guozi Yang
- Cancer Center, the First Hospital of Jilin University, Changchun 130021, China.
- Department of Radiation-Oncology, the First Hospital of Jilin University, Changchun 130021, China.
| | - Zhenyu Pan
- Department of Radiation-Oncology, the First Hospital of Jilin University, Changchun 130021, China.
| | - Yuguang Zhao
- Cancer Center, the First Hospital of Jilin University, Changchun 130021, China.
| | - Xinyue Liang
- Cancer Center, the First Hospital of Jilin University, Changchun 130021, China.
| | - Wei Li
- Cancer Center, the First Hospital of Jilin University, Changchun 130021, China.
| | - Lu Cai
- Cancer Center, the First Hospital of Jilin University, Changchun 130021, China.
- The Pediatric Research Institute, the Departments of Pediatrics, Radiation Oncology, Pharmacology and Toxicology of the University of Louisville, Louisville, KY 40202, USA.
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Yang G, Li W, Jiang H, Liang X, Zhao Y, Yu D, Zhou L, Wang G, Tian H, Han F, Cai L, Cui J. Low-dose radiation may be a novel approach to enhance the effectiveness of cancer therapeutics. Int J Cancer 2016; 139:2157-68. [PMID: 27299986 DOI: 10.1002/ijc.30235] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Revised: 05/01/2016] [Accepted: 06/06/2016] [Indexed: 12/26/2022]
Abstract
It has been generally accepted that both natural and man-made sources of ionizing radiation contribute to human exposure and consequently pose a possible risk to human health. However, accumulating evidence has shown that the biological effects of low-dose radiation (LDR) are different from those of high-dose radiation. LDR can stimulate proliferation of normal cells and activate their defense systems, while these biological effects are not observed in some cancer cell types. Although there is still no concordance on this matter, the fact that LDR has the potential to enhance the effects of cancer therapeutics and reduce the toxic side effects of anti-cancer therapy has garnered significant interest. Here, we provide an overview of the current knowledge regarding the experimental data detailing the different responses of normal and cancer tissues to LDR, the underlying mechanisms, and its significance in clinical application.
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Affiliation(s)
- Guozi Yang
- Cancer Center, The First Hospital of Jilin University, Changchun, 130021, China.,Department of Radiation-Oncology, The First Hospital of Jilin University, Changchun, 130021, China
| | - Wei Li
- Cancer Center, The First Hospital of Jilin University, Changchun, 130021, China
| | - Hongyu Jiang
- Health Examination Center, The First Hospital of Jilin University, Changchun, 130021, China
| | - Xinyue Liang
- Cancer Center, The First Hospital of Jilin University, Changchun, 130021, China
| | - Yuguang Zhao
- Cancer Center, The First Hospital of Jilin University, Changchun, 130021, China
| | - Dehai Yu
- Cancer Center, The First Hospital of Jilin University, Changchun, 130021, China
| | - Lei Zhou
- Cancer Center, The First Hospital of Jilin University, Changchun, 130021, China
| | - Guanjun Wang
- Cancer Center, The First Hospital of Jilin University, Changchun, 130021, China
| | - Huimin Tian
- Cancer Center, The First Hospital of Jilin University, Changchun, 130021, China
| | - Fujun Han
- Cancer Center, The First Hospital of Jilin University, Changchun, 130021, China
| | - Lu Cai
- Cancer Center, The First Hospital of Jilin University, Changchun, 130021, China. .,Kosair Children's Hospital Research Institute, Departments of Pediatrics, Radiation Oncology, Pharmacology and Toxicology of the University of Louisville, Louisville, KY, 40202.
| | - Jiuwei Cui
- Cancer Center, The First Hospital of Jilin University, Changchun, 130021, China.
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The role of protein kinase C alpha translocation in radiation-induced bystander effect. Sci Rep 2016; 6:25817. [PMID: 27165942 PMCID: PMC4863171 DOI: 10.1038/srep25817] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 04/22/2016] [Indexed: 01/24/2023] Open
Abstract
Ionizing radiation is a well known human carcinogen. Evidence accumulated over the past decade suggested that extranuclear/extracellular targets and events may also play a critical role in modulating biological responses to ionizing radiation. However, the underlying mechanism(s) of radiation-induced bystander effect is still unclear. In the current study, AL cells were irradiated with alpha particles and responses of bystander cells were investigated. We found out that in bystander AL cells, protein kinase C alpha (PKCα) translocated from cytosol to membrane fraction. Pre-treatment of cells with PKC translocation inhibitor chelerythrine chloride suppressed the induced extracellular signal-regulated kinases (ERK) activity and the increased cyclooxygenase 2 (COX-2) expression as well as the mutagenic effect in bystander cells. Furthermore, tumor necrosis factor alpha (TNFα) was elevated in directly irradiated but not bystander cells; while TNFα receptor 1 (TNFR1) increased in the membrane fraction of bystander cells. Further analysis revealed that PKC activation caused accelerated internalization and recycling of TNFR1. Our data suggested that PKCα translocation may occur as an early event in radiation-induced bystander responses and mediate TNFα-induced signaling pathways that lead to the activation of ERK and up-regulation of COX-2.
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Zhao Y, Zhong R, Sun L, Jia J, Ma S, Liu X. Ionizing radiation-induced adaptive response in fibroblasts under both monolayer and 3-dimensional conditions. PLoS One 2015; 10:e0121289. [PMID: 25807079 PMCID: PMC4373882 DOI: 10.1371/journal.pone.0121289] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2014] [Accepted: 01/29/2015] [Indexed: 01/01/2023] Open
Abstract
To observe the adaptive response (AR) induced by ionizing radiation in human fibroblasts under monolayer and 3-dimensional (3-D) condition. Three kinds of fibroblasts were cultured under both monolayer and 3-D condition. Immunofluorescent staining was used to detect the γ-H2AX foci and the morphological texture. Trypan blue staining was used to detect the cell death. Western blot was used to detect the expressions of γ-H2AX, p53 and CDKN1A/p21 (p21). We found that DNA damage increased in a dose-dependent and time-dependent manner after high doses of radiation. When cells were pretreated with a priming low dose of radiation followed by high dose radiation, DNA damage was attenuated under both monolayer and 3-D condition, and the adaptive response (AR) was induced. Additionally, the morphology of cells under monolayer and 3-D conditions were different, and radiation also induced AR according to morphological texture analysis. Priming low dose radiation induced AR both under monolayer and 3-D condition. Interestingly, 3-D microenvironment made cells more sensitive to radiation. The expression of p53 and p21 was changed and indicated that they might participate in the regulation of AR.
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Affiliation(s)
- Yinlong Zhao
- Key Laboratory of Radiobiology (Ministry of Health), School of Public Health, Jilin University, Changchun, China
- Dept. Nuclear Medicine, 2nd Hospital Jilin University, Changchun, China
| | - Rui Zhong
- Key Laboratory of Radiobiology (Ministry of Health), School of Public Health, Jilin University, Changchun, China
| | - Liguang Sun
- Dept. Translational Medicine, 1st Hospital Jilin University, Changchun, China
| | - Jie Jia
- Dept. Ultrasound, China-Japan Union Hospital, Changchun, China
| | - Shumei Ma
- Key Laboratory of Radiobiology (Ministry of Health), School of Public Health, Jilin University, Changchun, China
- * E-mail: (SM); (XL)
| | - Xiaodong Liu
- Key Laboratory of Radiobiology (Ministry of Health), School of Public Health, Jilin University, Changchun, China
- * E-mail: (SM); (XL)
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Wang ZC, Wang JF, Li YB, Guo CX, Liu Y, Fang F, Gong SL. Involvement of endoplasmic reticulum stress in apoptosis of testicular cells induced by low-dose radiation. ACTA ACUST UNITED AC 2013; 33:551-558. [PMID: 23904376 DOI: 10.1007/s11596-013-1157-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Revised: 12/12/2012] [Indexed: 02/04/2023]
Abstract
The study examined the role of endoplasmic reticulum stress (ERS) and signaling pathways of inositol-requiring enzyme-1 (IRE1), RNA-activated protein kinase-like ER kinase (PERK) and activating transcription factor-6 (ATF6) in apoptosis of mouse testicular cells treated with low-dose radiation (LDR). In the dose-dependent experiment, the mice were treated with whole-body X-ray irradiation at different doses (25, 50, 75, 100 or 200 mGy) and sacrificed 12 h later. In the time-dependent experiment, the mice were exposed to 75 mGy X-ray irradiation and killed at different time points (3, 6, 12, 18 or 24 h). Testicular cells were harvested for experiments. H(2)O(2) and NO concentrations, and Ca(2+)-ATPase activity were detected by biochemical assays, the calcium ion concentration ([Ca(2+)]i) by flow cytometry using fluo-3 probe, and GRP78 mRNA and protein expressions by quantitative real-time RT-PCR (qRT-PCR) and Western blotting, respectively. The mRNA expressions of S-XBP1, JNK, caspase-12 and CHOP were measured by qRT-PCR, and the protein expressions of IRE1α, S-XBP1, p-PERK, p-eIF2α, ATF6 p50, p-JNK, pro-caspase-12, cleaved caspase-12 and CHOP by Western blotting. The results showed that the concentrations of H2O2 and NO, the mRNA expressions of GRP78, S-XBP1, JNK, caspase-12 and CHOP, and the protein expressions of GRP78, S-XBP1, IRE1α, p-PERK, p-eIF2α, ATF6 p50, p-JNK, pro-caspase-12, cleaved caspase-12 and CHOP were significantly increased in a time- and dose-dependent manner after LDR. But the [Ca(2+)]i and Ca(2+)-ATPase activities were significantly decreased in a time- and dose-dependent manner. It was concluded that the ERS, regulated by IRE1, PERK and ATF6 pathways, is involved in the apoptosis of testicular cells in LDR mice, which is associated with ERS-apoptotic signaling molecules of JNK, caspase-12 and CHOP.
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Affiliation(s)
- Zhi-Cheng Wang
- Key Laboratory of Radiobiology of Ministry of Health, School of Public Health, Jilin University, Changchun, 130021, China
| | - Jian-Feng Wang
- Key Laboratory of Radiobiology of Ministry of Health, School of Public Health, Jilin University, Changchun, 130021, China
| | - Yan-Bo Li
- Key Laboratory of Radiobiology of Ministry of Health, School of Public Health, Jilin University, Changchun, 130021, China.,School of Public Health and Family Medicine, Capital Medical University, Beijing, 100069, China
| | - Cai-Xia Guo
- School of Public Health and Family Medicine, Capital Medical University, Beijing, 100069, China
| | - Yang Liu
- Key Laboratory of Radiobiology of Ministry of Health, School of Public Health, Jilin University, Changchun, 130021, China
| | - Fang Fang
- Key Laboratory of Radiobiology of Ministry of Health, School of Public Health, Jilin University, Changchun, 130021, China.
| | - Shou-Liang Gong
- Key Laboratory of Radiobiology of Ministry of Health, School of Public Health, Jilin University, Changchun, 130021, China.
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Shin SC, Kang YM, Kim HS. Life Span and Thymic Lymphoma Incidence in High- and Low-Dose-Rate Irradiated AKR/J Mice and Commonly Expressed Genes. Radiat Res 2010; 174:341-6. [DOI: 10.1667/rr1946.1] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Hu B, Shen B, Su Y, Geard CR, Balajee AS. Protein kinase C epsilon is involved in ionizing radiation induced bystander response in human cells. Int J Biochem Cell Biol 2009; 41:2413-21. [PMID: 19577658 DOI: 10.1016/j.biocel.2009.06.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2009] [Revised: 06/16/2009] [Accepted: 06/29/2009] [Indexed: 12/14/2022]
Abstract
Our earlier study demonstrated the induction of PKC isoforms (betaII, PKC-alpha/beta, PKC-theta) by ionizing radiation induced bystander response in human cells. In this study, we extended our investigation to yet another important member of PKC family, PKC epsilon (PKCepsilon). PKCepsilon functions both as an anti-apoptotic and pro-apoptotic protein and it is the only PKC isozyme implicated in oncogenesis. Given the importance of PKCepsilon in oncogenesis, we wished to determine whether or not PKCepsilon is involved in bystander response. Gene expression array analysis demonstrated a 2-3-fold increase in PKCepsilon expression in the bystander human primary fibroblast cells that were co-cultured in double-sided Mylar dishes for 3h with human primary fibroblast cells irradiated with 5Gy of alpha-particles. The elevated PKCepsilon expression in bystander cells was verified by quantitative real time PCR. Suppression of PKCepsilon expression by small molecule inhibitor Bisindolylmaleimide IX (Ro 31-8220) considerably reduced the frequency of micronuclei (MN) induced both by 5Gy of gamma-rays (low LET) and alpha-particles (high LET) in bystander cells. Similar cytoprotective effects were observed in bystander cells after siRNA mediated silencing of PKCepsilon suggestive of its critical role in mediating some of the bystander effects (BE). Our novel study suggests the possibility that PKC signaling pathway may be a critical molecular target for suppression of ionizing radiation induced biological effects in bystander cells.
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Affiliation(s)
- Burong Hu
- Center for Radiological Research, Department of Radiation Oncology, College of Physicians and Surgeons, 630 West, 168th Street, VC-11, Room 239, Columbia University, New York, NY 10032, USA
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Shin SC, Kang YM, Jin YW, Kim HS. Relative morphological abnormalities of sperm in the caudal epididymis of high- and low-dose-rate gamma-irradiated ICR mice. JOURNAL OF RADIATION RESEARCH 2009; 50:261-266. [PMID: 19531924 DOI: 10.1269/jrr.09005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
This study evaluated the effects of low dose radiation on spermatogenic cells using the morphological characteristics of sperm in the caudal epididymis of ICR mice. In this study, six abnormal sperm shapes (amorphous heads, blunt hooks, excessive hooks, two heads and tails, folded tails and short tails) were observed at eight days after gamma-irradiation ((137)Cs, 0, 0.2, 0.5, 1, 2 or 4 Gy) with both a high-dose-rate (0.8 Gy/min) and a low-dose-rate (0.7 mGy/hr). Fewer abnormal forms of sperm were observed in low-dose-rate irradiated mice than in mice that received a high-dose-rate irradiation (P = 0.002). The ratio of the dose rate effect among low-dose-rate irradiated mice to high-dose-rate irradiated mice was approximately 0.6. In addition, sperm with blunt hooks and two heads and tails significantly increased in number after irradiation, potentially providing an endpoint marker for estimating the effects of radiation. This study suggests that low-dose-rate (0.7 mGy/hr) radiation does not damage stem spermatogonia and probably stimulates repair in damaged spermatogonial stem cells in male mice.
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Affiliation(s)
- Suk Chul Shin
- Radiation Health Research Institute, Korea Hydro & Nuclear Power Co., Ltd., 388-1 Ssangmun-dong, Dobong-gu, Seoul, Korea
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Jiang H, Xu Y, Li W, Ma K, Cai L, Wang G. Low-Dose Radiation Does Not Induce Proliferation in Tumor CellsIn VitroandIn Vivo. Radiat Res 2008; 170:477-87. [DOI: 10.1667/rr1132.1] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Jiang H, Li W, Li X, Cai L, Wang G. Low-dose radiation induces adaptive response in normal cells, but not in tumor cells: in vitro and in vivo studies. JOURNAL OF RADIATION RESEARCH 2008; 49:219-230. [PMID: 18296871 DOI: 10.1269/jrr.07072] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Biological effects of low-dose radiation (LDR) are distinguishable from those of high-dose radiation. Hormetic and adaptive responses are such two examples. However, whether adaptive response could be induced in tumor cells by LDR, especially under in vivo condition, remains elusive, and was systemically investigated in the present study. Four tumor cell lines: two human leukemia cell lines (erythroleukemia cell line K562, and acute promyelocytic leukemia cell line HL60), and two human solid tumor cell lines (lung carcinoma cell line NCI-H446 and glioma cell line U251), along with one normal cell line (human fibroblast cells, MRC-5), were irradiated with LDR at 75 mGy of X-rays as D1 and then 4 Gy of X-rays as D2 (i.e.: D1 + D2) or only 4 Gy of X-rays (D2 alone). Three tumor-bearing animal models were also used to further define whether LDR induces adaptive response in tumor cells in vivo. Adaptive response was observed only in normal cell line, but not in four tumor cell lines, in response to LDR, showing a resistance to subsequent D2-induced cell growth inhibition. Three tumor-bearing mouse models with U251, NCI-H446 or S180 tumor cells were used to confirm that pre-exposure of tumor-bearing mice to D1 did not induce the resistance of tumor cells in vivo to D2-induced tumor growth inhibition. Furthermore, a higher apoptotic effect, along with higher expression of apoptosis-related genes P53 and Bax and lower expression of anti-apoptosis gene Bcl-2, was found in tumor cells of the tumor-bearing mice exposed to D1 + D2 than those in the tumor cells of the tumor-bearing mice exposed to D2 alone. These results suggest that LDR does not induce adaptive response in the tumor cells under both in vitro and in vivo conditions, which is a very important, clinic-relevant phenomenon.
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Affiliation(s)
- Hongyu Jiang
- Department of Hematology at the First Clinical College, Jilin University, Changchum, China
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Liu G, Gong P, Zhao H, Wang Z, Gong S, Cai L. Effect of low-level radiation on the death of male germ cells. Radiat Res 2006; 165:379-89. [PMID: 16579650 DOI: 10.1667/rr3528.1] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Hormetic and adaptive responses induced by low-level radiation in hematopoietic and immune systems have been observed, as shown by stimulatory effects on cell growth and resistance to subsequent radiation-induced cytogenetic damage. However, in terms of cell death by apoptosis, the effects of low-level radiation are controversial: Some studies showed decreased apoptosis in response to low-level radiation while others showed increased apoptosis. This controversy may be related to the radiation doses or dose rates and also, more importantly, to the cell types. Testes are one of the most radiosensitive organs. The loss of male germ cells after exposure to ionizing radiation has been attributed to apoptosis. In the present study, the effects of low-level radiation at doses up to 200 mGy on mouse male germ cells in terms of apoptosis and the expression of apoptosis-related proteins were examined at different times after whole-body exposure of mice to low-level radiation. In addition, the effect of pre-exposure to low-level radiation on subsequent cell death induced by high doses of radiation was examined to explore the possibility of low-level radiation-induced adaptive response. The results showed that low-level radiation in the dose range of 25-200 mGy induced significant increases in apoptosis in both spermatogonia and spermatocytes, with the maximal effect at 75 mGy. The increased apoptosis is most likely associated with Trp53 protein expression. Furthermore, 75 mGy low-level radiation given pre-irradiation led to an adaptive response of seminiferous germ cells to subsequent high-level radiation-induced apoptosis. These results suggest that low-level radiation induces increased apoptosis in male germ cells but also induces a significant adaptive response that decreases cell death after a subsequent high-dose irradiation.
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Affiliation(s)
- Guangwei Liu
- Ministry of Health Radiobiology Research Unit, School of Public Health, Jilin University, Changchun, China 130021
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Abstract
The aim was to review the present state of knowledge on the adaptive response and attempt to redefine the acknowledged model in the framework of the transcription-based model of damage fixation of Radford (2002). Data are reviewed that suggest that the priming stimulus is the source of signalling that eventually leads to expression of the adaptive response. For a certain time, the 'primed' cell can then respond to the challenge dose by an increased recovery, as compared with the control one. An essential part of the adaptive response is generation or receipt and transmission of a signal that is the direct cause of initiation of a cellular response that diminishes the effects of DNA damage. The often accepted view that DNA repair is stimulated in the 'primed' and challenged cell is not supported by all the available data. Taking into account the abrogation of radio-adaptation by poly(ADP-ribosylation) inhibitors applied simultaneously with the challenge dose and the fact that adaptation is revealed as a decrease in chromosomal aberration frequency, one can apply to the adaptive response the same arguments as those that support the fixation model of Radford. Adaptive response (at least in part) is due to diminished fixation of double-strand breaks in the transcription factories by the mechanism proposed by Radford.
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Affiliation(s)
- I Szumiel
- Department of Radiology and Health Protection, Institute of Nuclear Chemistry and Technology, Warsaw, Poland.
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Miura Y. Oxidative stress, radiation-adaptive responses, and aging. JOURNAL OF RADIATION RESEARCH 2004; 45:357-372. [PMID: 15613781 DOI: 10.1269/jrr.45.357] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Organisms living in an aerobic environment were forced to evolve effective cellular strategies to detoxify reactive oxygen species. Besides diverse antioxidant enzymes and compounds, DNA repair enzymes, and disassembly systems, which remove damaged proteins, regulation systems that control transcription, translation, and activation have also been developed. The adaptive responses, especially those to radiation, are defensive regulation mechanisms by which oxidative stress (conditioning irradiation) elicits a response against damage because of subsequent stress (challenging irradiation). Although many researchers have investigated these molecular mechanisms, they remain obscure because of their complex signaling pathways and the involvement of various proteins. This article reviews the factors concerned with radiation-adaptive response, the signaling pathways activated by conditioning irradiation, and the effects of aging on radiation-adaptive response. The proteomics approach is also introduced, which is a useful method for studying stress response in cells.
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Affiliation(s)
- Yuri Miura
- Redox regulation research group, Tokyo Metropolitan Institute of Gerontology, Itabashi-ku. Tokyo, Japan.
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Kondo H, Park SH, Watanabe K, Yamamoto Y, Akashi M. Polyphenol (−)-epigallocatechin gallate inhibits apoptosis induced by irradiation in human HaCaT keratinocytes. Biochem Biophys Res Commun 2004; 316:59-64. [PMID: 15003511 DOI: 10.1016/j.bbrc.2004.01.175] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2004] [Indexed: 02/04/2023]
Abstract
Green tea is a rich source of polyphenols, and (-)-epigallocatechin-3-gallate (EGCG) is a major constituent of green tea polyphenols. In the present study, we investigated the effect of EGCG on apoptosis induced by irradiation in the human keratinocytic cell line HaCaT. Irradiation by gamma-ray induced apoptosis with concomitant cleavage of caspase-3 and its in vivo substrate poly(ADP-ribose) polymerase. Treatment of cells with EGCG inhibited irradiation-induced apoptosis as detected by Hoechst staining and internucleosomal cleavage of DNA, and prevented the cleavage of these proteins by irradiation. We also found that the treatment of cells with EGCG alone suppressed cell growth and induced apoptosis in these cells. Our results suggest that EGCG inhibits irradiation-induced apoptosis by inactivating the caspase pathway in HaCaT cells. Our study also indicates that EGCG has a dual effect on the survival of these keratinocytes.
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Affiliation(s)
- Hisayoshi Kondo
- Department of Radiation Emergency Medicine, National Institute of Radiological Sciences, Chiba 263-6555, Japan
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