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Luukkonen J, Höytö A, Sokka M, Syväoja J, Juutilainen J, Naarala J. Genomic instability induced by radiation-mimicking chemicals is not associated with persistent mitochondrial degeneration. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2022; 61:29-36. [PMID: 34331120 PMCID: PMC8897345 DOI: 10.1007/s00411-021-00927-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 06/21/2021] [Indexed: 06/13/2023]
Abstract
Ionizing radiation has been shown to cause induced genomic instability (IGI), which is defined as a persistently increased rate of genomic damage in the progeny of the exposed cells. In this study, IGI was investigated by exposing human SH-SY5Y neuroblastoma cells to hydroxyurea and zeocin, two chemicals mimicking different DNA-damaging effects of ionizing radiation. The aim was to explore whether IGI was associated with persistent mitochondrial dysfunction. Changes to mitochondrial function were assessed by analyzing mitochondrial superoxide production, mitochondrial membrane potential, and mitochondrial activity. The formation of micronuclei was used to determine immediate genetic damage and IGI. Measurements were performed either immediately, 8 days, or 15 days following exposure. Both hydroxyurea and zeocin increased mitochondrial superoxide production and affected mitochondrial activity immediately after exposure, and mitochondrial membrane potential was affected by zeocin, but no persistent changes in mitochondrial function were observed. IGI became manifested 15 days after exposure in hydroxyurea-exposed cells. In conclusion, immediate responses in mitochondrial function did not cause persistent dysfunction of mitochondria, and this dysfunction was not required for IGI in human neuroblastoma cells.
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Affiliation(s)
- Jukka Luukkonen
- Department of Environmental and Biological Sciences, University of Eastern Finland, Yliopistonranta 1, P.O. Box 1627, 70211, Kuopio, Finland.
| | - Anne Höytö
- Department of Environmental and Biological Sciences, University of Eastern Finland, Yliopistonranta 1, P.O. Box 1627, 70211, Kuopio, Finland
- STUK-Radiation and Nuclear Safety Authority, Helsinki, Finland
| | - Miiko Sokka
- Department of Environmental and Biological Sciences, University of Eastern Finland, Joensuu, Finland
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI, USA
| | - Juhani Syväoja
- Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland
| | - Jukka Juutilainen
- Department of Environmental and Biological Sciences, University of Eastern Finland, Yliopistonranta 1, P.O. Box 1627, 70211, Kuopio, Finland
| | - Jonne Naarala
- Department of Environmental and Biological Sciences, University of Eastern Finland, Yliopistonranta 1, P.O. Box 1627, 70211, Kuopio, Finland
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2
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Electromagnetic Fields, Genomic Instability and Cancer: A Systems Biological View. Genes (Basel) 2019; 10:genes10060479. [PMID: 31242701 PMCID: PMC6627294 DOI: 10.3390/genes10060479] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Revised: 06/19/2019] [Accepted: 06/22/2019] [Indexed: 12/12/2022] Open
Abstract
This review discusses the use of systems biology in understanding the biological effects of electromagnetic fields, with particular focus on induction of genomic instability and cancer. We introduce basic concepts of the dynamical systems theory such as the state space and attractors and the use of these concepts in understanding the behavior of complex biological systems. We then discuss genomic instability in the framework of the dynamical systems theory, and describe the hypothesis that environmentally induced genomic instability corresponds to abnormal attractor states; large enough environmental perturbations can force the biological system to leave normal evolutionarily optimized attractors (corresponding to normal cell phenotypes) and migrate to less stable variant attractors. We discuss experimental approaches that can be coupled with theoretical systems biology such as testable predictions, derived from the theory and experimental methods, that can be used for measuring the state of the complex biological system. We also review potentially informative studies and make recommendations for further studies.
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3
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Luukkonen J, Höytö A, Viluksela M, Juutilainen J, Naarala J. TCDD-induced mitochondrial superoxide production does not lead to mitochondrial degeneration or genomic instability in human SH-SY5Y neuroblastoma cells. Toxicol In Vitro 2017; 44:213-218. [PMID: 28673561 DOI: 10.1016/j.tiv.2017.06.030] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 05/30/2017] [Accepted: 06/29/2017] [Indexed: 01/18/2023]
Abstract
Several genotoxic and non-genotoxic agents have been reported to cause delayed genetic damage in the progeny of the exposed cells. Such induced genomic instability (IGI) may be a driving force in carcinogenesis, and it is thus highly important to understand the cellular events accompanying it. The aim of this study was to investigate whether 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) affects mitochondrial integrity and can consequently induce genomic instability. Mitochondrial integrity was evaluated by measuring mitochondrial superoxide production, mitochondrial membrane potential, and mitochondrial activity. Micronucleus formation was used to assess immediate genetic damage and IGI. The assays were performed either immediately, 8 or 15d after the exposure. Mitochondrial superoxide production was increased by TCDD immediately after the exposure. No consistent effects on mitochondrial integrity were observed at later time points, although slightly decreased mitochondrial membrane potential at 8d and increased mitochondrial superoxide potential production at 15 after exposure were observed in the TCDD-exposed cells. TCDD did not cause immediate genetic damage, and significant IGI was not observed. In conclusion, the present results suggest that immediate TCDD-induced increase in mitochondrial superoxide level does not lead to persistent loss of mitochondrial integrity or IGI in human SH-SY5Y neuroblastoma cells.
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Affiliation(s)
- Jukka Luukkonen
- University of Eastern Finland, Department of Environmental and Biological Sciences, Yliopistonranta 1, P.O. Box 1627, FI-70211 Kuopio, Finland.
| | - Anne Höytö
- University of Eastern Finland, Department of Environmental and Biological Sciences, Yliopistonranta 1, P.O. Box 1627, FI-70211 Kuopio, Finland
| | - Matti Viluksela
- University of Eastern Finland, Department of Environmental and Biological Sciences, Yliopistonranta 1, P.O. Box 1627, FI-70211 Kuopio, Finland; National Institute for Health and Welfare, Environmental Health Unit, Kuopio, Finland
| | - Jukka Juutilainen
- University of Eastern Finland, Department of Environmental and Biological Sciences, Yliopistonranta 1, P.O. Box 1627, FI-70211 Kuopio, Finland
| | - Jonne Naarala
- University of Eastern Finland, Department of Environmental and Biological Sciences, Yliopistonranta 1, P.O. Box 1627, FI-70211 Kuopio, Finland
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4
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Luukkonen J, Liimatainen A, Juutilainen J, Naarala J. Induction of genomic instability, oxidative processes, and mitochondrial activity by 50Hz magnetic fields in human SH-SY5Y neuroblastoma cells. Mutat Res 2013; 760:33-41. [PMID: 24374227 DOI: 10.1016/j.mrfmmm.2013.12.002] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Revised: 12/13/2013] [Accepted: 12/19/2013] [Indexed: 11/26/2022]
Abstract
Epidemiological studies have suggested that exposure to 50Hz magnetic fields (MF) increases the risk of childhood leukemia, but there is no mechanistic explanation for carcinogenic effects. In two previous studies we have observed that a 24-h pre-exposure to MF alters cellular responses to menadione-induced DNA damage. The aim of this study was to investigate the cellular changes that must occur already during the first 24h of exposure to MF, and to explore whether the MF-induced changes in DNA damage response can lead to genomic instability in the progeny of the exposed cells. In order to answer these questions, human SH-SY5Y neuroblastoma cells were exposed to a 50-Hz, 100-μT MF for 24h, followed by 3-h exposure to menadione. The main finding was that MF exposure was associated with increased level of micronuclei, used as an indicator of induced genomic instability, at 8 and 15d after the exposures. Other delayed effects in MF-exposed cells included increased mitochondrial activity at 8d, and increased reactive oxygen species (ROS) production and lipid peroxidation at 15d after the exposures. Oxidative processes (ROS production, reduced glutathione level, and mitochondrial superoxide level) were affected by MF immediately after the exposure. In conclusion, the present results suggest that MF exposure disturbs oxidative balance immediately after the exposure, which might explain our previous findings on MF altered cellular responses to menadione-induced DNA damage. Persistently elevated levels of micronuclei were found in the progeny of MF-exposed cells, indicating induction of genomic instability.
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Affiliation(s)
- Jukka Luukkonen
- Department of Environmental Science, University of Eastern Finland, P.O. Box 1627, FI-70211 Kuopio, Finland.
| | - Anu Liimatainen
- Department of Environmental Science, University of Eastern Finland, P.O. Box 1627, FI-70211 Kuopio, Finland
| | - Jukka Juutilainen
- Department of Environmental Science, University of Eastern Finland, P.O. Box 1627, FI-70211 Kuopio, Finland
| | - Jonne Naarala
- Department of Environmental Science, University of Eastern Finland, P.O. Box 1627, FI-70211 Kuopio, Finland
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5
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Karotki AV, Baverstock K. What mechanisms/processes underlie radiation-induced genomic instability? Cell Mol Life Sci 2012; 69:3351-60. [PMID: 22955377 PMCID: PMC11115179 DOI: 10.1007/s00018-012-1148-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2012] [Revised: 08/22/2012] [Accepted: 08/23/2012] [Indexed: 01/11/2023]
Abstract
Radiation-induced genomic instability is a modification of the cell genome found in the progeny of irradiated somatic and germ cells but that is not confined on the initial radiation-induced damage and may occur de novo many generations after irradiation. Genomic instability in the germ line does not follow Mendelian segregation and may have unpredictable outcomes in every succeeding generation. This phenomenon, for which there is extensive experimental data and some evidence in human populations exposed to ionising radiation, is not taken into account in health risk assessments. It poses an unknown morbidity/mortality burden. Based on experimental data derived over the last 20 years (up to January 2012) six mechanistic explanations for the phenomenon have been proposed in the peer-reviewed literature. This article compares these hypotheses with the empirical data to test their fitness to explain the phenomenon. As a conclusion, the most convincing explanation of radiation-induced genomic instability attributes it to an irreversible regulatory change in the dynamic interaction network of the cellular gene products, as a response to non-specific molecular damage, thus entailing the rejection of the machine metaphor for the cell in favour of one appropriate to a complex dissipative dynamic system, such as a whirlpool. It is concluded that in order to evaluate the likely morbidity/mortality associated with radiation-induced genomic instability, it will be necessary to study the damage to processes by radiation rather than damage to molecules.
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Affiliation(s)
- Andrei V. Karotki
- Radiation Group, International Agency for Research on Cancer, International Agency for Research on Cancer, 150 Cours A. Thomas, 69372 Lyon, France
| | - Keith Baverstock
- Department of Environmental Science, University of Eastern Finland, Kuopio Campus, PL 1627, 70211 Kuopio, Finland
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6
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Korkalainen M, Huumonen K, Naarala J, Viluksela M, Juutilainen J. Dioxin induces genomic instability in mouse embryonic fibroblasts. PLoS One 2012; 7:e37895. [PMID: 22666406 PMCID: PMC3362596 DOI: 10.1371/journal.pone.0037895] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Accepted: 04/30/2012] [Indexed: 12/04/2022] Open
Abstract
Ionizing radiation and certain other exposures have been shown to induce genomic instability (GI), i.e., delayed genetic damage observed many cell generations later in the progeny of the exposed cells. The aim of this study was to investigate induction of GI by a nongenotoxic carcinogen, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Mouse embryonic fibroblasts (C3H10T1/2) were exposed to 1, 10 or 100 nM TCDD for 2 days. Micronuclei (MN) and expression of selected cancer-related genes were assayed both immediately and at a delayed point in time (8 days). For comparison, similar experiments were done with cadmium, a known genotoxic agent. TCDD treatment induced an elevated frequency of MN at 8 days, but not directly after the exposure. TCDD-induced alterations in gene expression were also mostly delayed, with more changes observed at 8 days than at 2 days. Exposure to cadmium produced an opposite pattern of responses, with pronounced effects immediately after exposure but no increase in MN and few gene expression changes at 8 days. Although all responses to TCDD alone were delayed, menadione-induced DNA damage (measured by the Comet assay), was found to be increased directly after a 2-day TCDD exposure, indicating that the stability of the genome was compromised already at this time point. The results suggested a flat dose-response relationship consistent with dose-response data reported for radiation-induced GI. These findings indicate that TCDD, although not directly genotoxic, induces GI, which is associated with impaired DNA damage response.
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Affiliation(s)
- Merja Korkalainen
- Department of Environmental Health, National Institute for Health and Welfare, Kuopio, Finland
- * E-mail:
| | - Katriina Huumonen
- Department of Environmental Science, University of Eastern Finland, Kuopio, Finland
| | - Jonne Naarala
- Department of Environmental Science, University of Eastern Finland, Kuopio, Finland
| | - Matti Viluksela
- Department of Environmental Health, National Institute for Health and Welfare, Kuopio, Finland
| | - Jukka Juutilainen
- Department of Environmental Science, University of Eastern Finland, Kuopio, Finland
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7
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Hafer K, Rivina Y, Schiestl RH. Yeast DEL assay detects protection against radiation-induced cytotoxicity and genotoxicity: adaptation of a microtiter plate version. Radiat Res 2010; 174:719-26. [PMID: 21128795 DOI: 10.1667/rr2059.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The DEL assay in yeast detects DNA deletions that are inducible by many carcinogens. Here we use the colorimetric agent MTS to adapt the yeast DEL assay for microwell plate measurement of ionizing radiation-induced cell killing and DNA deletions. Using the microwell-based DEL assay, cell killing and genotoxic DNA deletions both increased with radiation dose between 0 and 2000 Gy. We used the microwell-based DEL assay to assess the effectiveness of varying concentrations of five different radioprotectors, N-acetyl-l-cysteine, l-ascorbic acid, DMSO, Tempol and Amifostine, and one radiosensitizer, 5-bromo-2-deoxyuridine. The microwell format of the DEL assay was able to successfully detect protection against and sensitization to both radiation-induced cytotoxicity and genotoxicity. Such radioprotection and sensitization detected by the microwell-based DEL assay was validated and compared with similar measurements made using the traditional agar-based assay format. The yeast DEL assay in microwell format is an effective tool for rapidly detecting chemical protectors and sensitizers to ionizing radiation and is automatable for chemical high-throughput screening purposes.
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Affiliation(s)
- Kurt Hafer
- Department of Radiation Oncology, David Geffen School of Medicine at UCLA and UCLA School of Public Health, Los Angeles, California 90095, USA
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8
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Yokota Y, Funayama T, Hase Y, Hamada N, Kobayashi Y, Tanaka A, Narumi I. Enhanced micronucleus formation in the descendants of gamma-ray-irradiated tobacco cells: evidence for radiation-induced genomic instability in plant cells. Mutat Res 2010; 691:41-6. [PMID: 20633566 DOI: 10.1016/j.mrfmmm.2010.07.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2010] [Revised: 06/25/2010] [Accepted: 07/01/2010] [Indexed: 05/29/2023]
Abstract
Ionizing radiation-induced genomic instability has been documented in various end points such as chromosomal aberrations and mutations, which arises in the descendants of irradiated mammalian or yeast cells many generations after the initial insult. This study aimed at addressing radiation-induced genomic instability in higher plant tobacco cells. We thus investigated micronucleus (MN) formation and cell proliferation in tobacco cells irradiated with gamma-rays and their descendants. In gamma-irradiated cells, cell cycle was arrested at G2/M phase at around 24 h post-irradiation but released afterward. In contrast, MN frequency peaked at 48 h post-irradiation. Almost half of 40 Gy-irradiated cells had MN at 48 h post-irradiation, but proliferated as actively as sham-irradiated cells up to 120 h post-irradiation. Moreover, the descendants that have undergone at least 22 generations after irradiation still showed a two-fold MN frequency compared to sham-irradiated cells. This is the direct evidence for radiation-induced genomic instability in tobacco cells.
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Affiliation(s)
- Yuichiro Yokota
- Life Science and Biotechnology Division, Quantum Beam Science Directorate, Japan Atomic Energy Agency, 1233 Watanuki-machi, Takasaki, Gunma 370-1292, Japan.
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9
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Hafer K, Rivina L, Schiestl RH. Cell cycle dependence of ionizing radiation-induced DNA deletions and antioxidant radioprotection in Saccharomyces cerevisiae. Radiat Res 2010; 173:802-8. [PMID: 20518659 DOI: 10.1667/rr1661.1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The yeast DEL assay is an effective method for measuring intrachromosomal recombination events resulting in DNA deletions that when occurring in mammalian cells are often associated with genomic instability and carcinogenesis. Here we used the DEL assay to measure gamma-ray-induced DNA deletions throughout different phases of yeast culture growth. Whereas yeast survival differed by only up to twofold throughout the yeast growth phase, proliferating cells in lag and early exponential growth phases were tenfold more sensitive to ionizing radiation-induced DNA deletions than cells in stationary phase. Radiation-induced DNA deletion potential was found to correlate directly with the fraction of cells in S/G(2) phase. The ability of the antioxidants l-ascorbic acid and DMSO to protect against radiation-induced DNA deletions was also measured within the different phases of yeast culture growth. Yeast cells in lag and early exponential growth phases were uniquely protected by antioxidant treatment, whereas nondividing cells in stationary phase could not be protected against the induction of DNA deletions. These results are compared with those from mammalian cell studies, and the implications for radiation-induced carcinogenesis and radioprotection are discussed.
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Affiliation(s)
- Kurt Hafer
- Departments of Radiation Oncology, Pathology, David Geffen School of Medicine, UCLA, Los Angeles, CA 90095, USA
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10
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Reliene R, Pollard JM, Sobol Z, Trouiller B, Gatti RA, Schiestl RH. N-acetyl cysteine protects against ionizing radiation-induced DNA damage but not against cell killing in yeast and mammals. Mutat Res 2009; 665:37-43. [PMID: 19427509 DOI: 10.1016/j.mrfmmm.2009.02.016] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2008] [Revised: 02/14/2009] [Accepted: 02/28/2009] [Indexed: 05/27/2023]
Abstract
Ionizing radiation (IR) induces DNA strand breaks leading to cell death or deleterious genome rearrangements. In the present study, we examined the role of N-acetyl-L-cysteine (NAC), a clinically proven safe agent, for it's ability to protect against gamma-ray-induced DNA strand breaks and/or DNA deletions in yeast and mammals. In the yeast Saccharomyces cerevisiae, DNA deletions were scored by reversion to histidine prototrophy. Human lymphoblastoid cells were examined for the frequency of gamma-H2AX foci formation, indicative of DNA double strand break formation. DNA strand breaks were also measured in mouse peripheral blood by the alkaline comet assay. In yeast, NAC reduced the frequency of IR-induced DNA deletions. However, NAC did not protect against cell death. NAC also reduced gamma-H2AX foci formation in human lymphoblastoid cells but had no protective effect in the colony survival assay. NAC administration via drinking water fully protected against DNA strand breaks in mice whole-body irradiated with 1Gy but not with 4Gy. NAC treatment in the absence of irradiation was not genotoxic. These data suggest that, given the safety and efficacy of NAC in humans, NAC may be useful in radiation therapy to prevent radiation-mediated genotoxicity, but does not interfere with efficient cancer cell killing.
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Affiliation(s)
- Ramune Reliene
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
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11
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Radiation induction of delayed recombination in Schizosaccharomyces pombe. DNA Repair (Amst) 2008; 7:1250-61. [PMID: 18547878 DOI: 10.1016/j.dnarep.2008.04.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2007] [Revised: 02/15/2008] [Accepted: 04/05/2008] [Indexed: 11/24/2022]
Abstract
Ionizing radiation is known to induce delayed chromosome and gene mutations in the descendants of the irradiated tissue culture cells. Molecular mechanisms of such delayed mutations are yet to be elucidated, since high genomic complexity of mammalian cells makes it difficult to analyze. We now tested radiation induction of delayed recombination in the fission yeast Schizosaccharomyces pombe by monitoring the frequency of homologous recombination after X-irradiation. A reporter with 200 bp tandem repeats went through spontaneous recombination at a frequency of 1.0 x 10(-4), and the frequency increased dose-dependently to around 10 x 10(-4) at 500 Gy of X-irradiation. Although the repair of initial DNA damage was thought to be completed before the restart of cell division cycle, the elevation of the recombination frequency persisted for 8-10 cell generations after irradiation (delayed recombination). The delayed recombination suggests that descendants of the irradiated cells keep a memory of the initial DNA damage which upregulates recombination machinery for 8-10 generations even in the absence of DNA double-strand breaks (DSBs). Since radical scavengers were ineffective in inhibiting the delayed recombination, a memory by continuous production of DNA damaging agents such as reactive oxygen species (ROS) was excluded. Recombination was induced in trans in a reporter on chromosome III by a DNA DSB at a site on chromosome I, suggesting the untargeted nature of delayed recombination. Interestingly, Rad22 foci persisted in the X-irradiated population in parallel with the elevation of the recombination frequency. These results suggest that the epigenetic damage memory induced by DNA DSB upregulates untargeted and delayed recombination in S. pombe.
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12
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Hafer K, Iwamoto KS, Iwamoto KK, Scuric Z, Schiestl RH. Adaptive Response to Gamma Radiation in Mammalian Cells Proficient and Deficient in Components of Nucleotide Excision Repair. Radiat Res 2007; 168:168-74. [PMID: 17638404 DOI: 10.1667/rr0717.1] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2006] [Accepted: 03/23/2007] [Indexed: 11/03/2022]
Abstract
Cells preconditioned with low doses of low-linear energy transfer (LET) ionizing radiation become more resistant to later challenges of radiation. The mechanism(s) by which cells adaptively respond to radiation remains unclear, although it has been suggested that DNA repair induced by low doses of radiation increases cellular radioresistance. Recent gene expression profiles have consistently indicated that proteins involved in the nucleotide excision repair pathway are up-regulated after exposure to ionizing radiation. Here we test the role of the nucleotide excision repair pathway for adaptive response to gamma radiation in vitro. Wild-type CHO cells exhibited both greater survival and fewer HPRT mutations when preconditioned with a low dose of gamma rays before exposure to a later challenging dose. Cells mutated for ERCC1, ERCC3, ERCC4 or ERCC5 did not express either adaptive response to radiation; cells mutated for ERCC2 expressed a survival adaptive response but no mutation adaptive response. These results suggest that some components of the nucleotide excision repair pathway are required for phenotypic low-dose induction of resistance to gamma radiation in mammalian cells.
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Affiliation(s)
- Kurt Hafer
- Department of Radiation Oncology, UCLA School of Medicine and Public Health, Los Angeles, CA 90095, USA.
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13
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Rugo RE, Almeida KH, Hendricks CA, Jonnalagadda VS, Engelward BP. A single acute exposure to a chemotherapeutic agent induces hyper-recombination in distantly descendant cells and in their neighbors. Oncogene 2005; 24:5016-25. [PMID: 15856014 DOI: 10.1038/sj.onc.1208690] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Homologous recombination can induce tumorigenic sequence rearrangements. Here, we show that persistent hyper-recombination can be induced following exposure to a bifunctional alkylating agent, mitomycin C (MMC), and that the progeny of exposed cells induce a hyper-recombination phenotype in unexposed neighboring cells. Residual damage cannot be the cause of delayed recombination events, since recombination is observed after drug and template damage are diluted over a million-fold. Furthermore, not only do progeny of MMC-exposed cells induce recombination in unexposed cells (bystanders), but these bystanders can in turn induce recombination in their unexposed neighbors. Thus, a signal to induce homologous recombination can be passed from cell to cell. Although the underlying molecular mechanism is not yet known, these studies reveal that cells suffer consequences of damage long after exposure, and that can signal unexposed neighboring cells to respond similarly. Thus, a single acute exposure to a chemotherapeutic agent can cause long-term changes in genomic stability. If the results of these studies of mouse embryonic stem (ES) cells are generally applicable to many cell types, these results suggest that a relatively small number of cells could potentially induce a tissue-wide increase in the risk of de novo homologous recombination events.
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Affiliation(s)
- Rebecca E Rugo
- Biological Engineering Division, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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14
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Snyder AR, Morgan WF. Differential induction and activation of NF-kappaB transcription complexes in radiation-induced chromosomally unstable cell lines. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2005; 45:177-187. [PMID: 15645469 DOI: 10.1002/em.20092] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Radiation-induced genomic instability is a delayed effect of ionizing radiation that may contribute to radiation carcinogenesis. Prior microarray studies investigating gene expression changes in genomically unstable cell lines isolated after radiation exposure uncovered the differential expression of the NF-kappaB p105 mRNA. In this study, the functionality of the NF-kappaB pathway was examined to determine its role in regulating gene expression changes after oxidative stress in chromosomally stable and unstable human-hamster hybrid clones. Basal DNA-binding activity assays showed no significant differences between the clones; however, further experiments established differences in NF-kappaB induction in three chromosomally unstable clones after acute hydrogen peroxide treatment. A second assay was used to confirm this differential activity in the chromosomally unstable clones by studying reporter gene activation after treatment with hydrogen peroxide. Yet an initial upstream analysis of the pathway revealed no significant increase in the level of IkappaBalpha inhibitor protein in the unstable clones. Downstream tests analyzing the induction of the antiapoptotic target protein Bcl-2 found variable induction among the stable and unstable clones. These differences did not translate to a reduction in clonogenic survival after acute exposure to oxidative stress, as the irradiated but chromosomally stable clone displayed the most sensitivity. Due to its role in regulating a diverse set of cellular functions, including responses to oxidative stress, alterations in the NF-kappaB pathway in chromosomally unstable clones may regulate the differential physiology of a subset of chromosomally unstable clones and could contribute to the perpetuation of the phenotype. However, a specific role for defective induction and activation of this pathway remains unidentified.
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Affiliation(s)
- Andrew R Snyder
- Molecular and Cell Biology Graduate Program, University of Maryland, Baltimore, Maryland, USA.
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15
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Stone HB, Moulder JE, Coleman CN, Ang KK, Anscher MS, Barcellos-Hoff MH, Dynan WS, Fike JR, Grdina DJ, Greenberger JS, Hauer-Jensen M, Hill RP, Kolesnick RN, Macvittie TJ, Marks C, McBride WH, Metting N, Pellmar T, Purucker M, Robbins ME, Schiestl RH, Seed TM, Tomaszewski JE, Travis EL, Wallner PE, Wolpert M, Zaharevitz D. Models for Evaluating Agents Intended for the Prophylaxis, Mitigation and Treatment of Radiation Injuries Report of an NCI Workshop, December 3–4, 2003. Radiat Res 2004; 162:711-28. [PMID: 15548121 DOI: 10.1667/rr3276] [Citation(s) in RCA: 184] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
To develop approaches to prophylaxis/protection, mitigation and treatment of radiation injuries, appropriate models are needed that integrate the complex events that occur in the radiation-exposed organism. While the spectrum of agents in clinical use or preclinical development is limited, new research findings promise improvements in survival after whole-body irradiation and reductions in the risk of adverse effects of radiotherapy. Approaches include agents that act on the initial radiochemical events, agents that prevent or reduce progression of radiation damage, and agents that facilitate recovery from radiation injuries. While the mechanisms of action for most of the agents with known efficacy are yet to be fully determined, many seem to be operating at the tissue, organ or whole animal level as well as the cellular level. Thus research on prophylaxis/protection, mitigation and treatment of radiation injuries will require studies in whole animal models. Discovery, development and delivery of effective radiation modulators will also require collaboration among researchers in diverse fields such as radiation biology, inflammation, physiology, toxicology, immunology, tissue injury, drug development and radiation oncology. Additional investment in training more scientists in radiation biology and in the research portfolio addressing radiological and nuclear terrorism would benefit the general population in case of a radiological terrorism event or a large-scale accidental event as well as benefit patients treated with radiation.
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Affiliation(s)
- Helen B Stone
- National Cancer Institute, Bethesda, Maryland 20892, USA.
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Huang L, Grim S, Smith LE, Kim PM, Nickoloff JA, Goloubeva OG, Morgan WF. Ionizing radiation induces delayed hyperrecombination in Mammalian cells. Mol Cell Biol 2004; 24:5060-8. [PMID: 15143196 PMCID: PMC416413 DOI: 10.1128/mcb.24.11.5060-5068.2004] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Exposure to ionizing radiation can result in delayed effects that can be detected in the progeny of an irradiated cell multiple generations after the initial exposure. These effects are described under the rubric of radiation-induced genomic instability and encompass multiple genotoxic endpoints. We have developed a green fluorescence protein (GFP)-based assay and demonstrated that ionizing radiation induces genomic instability in human RKO-derived cells and in human hamster hybrid GM10115 cells, manifested as increased homologous recombination (HR). Up to 10% of cells cultured after irradiation produce mixed GFP(+/-) colonies indicative of delayed HR or, in the case of RKO-derived cells, mutation and deletion. Consistent with prior studies, delayed chromosomal instability correlated with delayed reproductive cell death. In contrast, cells displaying delayed HR showed no evidence of delayed reproductive cell death, and there was no correlation between delayed chromosomal instability and delayed HR, indicating that these forms of genome instability arise by distinct mechanisms. Because delayed hyperrecombination can be induced at doses of ionizing radiation that are not associated with significantly reduced cell viability, these data may have important implications for assessment of radiation risk and understanding the mechanisms of radiation carcinogenesis.
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Affiliation(s)
- Lei Huang
- Radiation Oncology Research Laboratory, Bressler Research Building, Room 7-002, University of Maryland, 655 W. Baltimore St., Baltimore, MD 21201-1559, USA.
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Persistent oxidative stress and gene expression changes in radiation-induced genomic instability. ACTA ACUST UNITED AC 2003. [DOI: 10.1016/s0531-5131(03)01152-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Current awareness on yeast. Yeast 2001; 18:1269-76. [PMID: 11561294 DOI: 10.1002/yea.689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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