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Tichy ED. Specialized Circuitry of Embryonic Stem Cells Promotes Genomic Integrity. Crit Rev Oncog 2023; 27:1-15. [PMID: 36734869 DOI: 10.1615/critrevoncog.2022042332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Embryonic stem cells (ESCs) give rise to all cell types of the organism. Given the importance of these cells in this process, ESCs must employ robust mechanisms to protect genomic integrity or risk catastrophic propagation of mutations throughout the organism. Should such an event occur in daughter cells that will eventually contribute to the germline, the overall species health could dramatically decline. This review describes several key mechanisms employed by ESCs that are unique to these cells, in order to maintain their genomic integrity. Additionally, the contributions of cell cycle regulators in modulating ESC differentiation, after DNA damage exposure, are also examined. Where data are available, findings reported in ESCs are extended to include observations described in induced pluripotent stem cells (IPSCs).
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Affiliation(s)
- Elisia D Tichy
- Department of Orthopaedic Surgery, Perelman School of Medicine, The University of Pennsylvania, 371 Stemmler Hall, 3450 Hamilton Walk, Philadelphia, PA 19104-6081
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2
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Radiation Response of Murine Embryonic Stem Cells. Cells 2020; 9:cells9071650. [PMID: 32660081 PMCID: PMC7408589 DOI: 10.3390/cells9071650] [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: 05/20/2020] [Revised: 06/18/2020] [Accepted: 07/01/2020] [Indexed: 12/13/2022] Open
Abstract
To understand the mechanisms of disturbed differentiation and development by radiation, murine CGR8 embryonic stem cells (mESCs) were exposed to ionizing radiation and differentiated by forming embryoid bodies (EBs). The colony forming ability test was applied for survival and the MTT test for viability determination after X-irradiation. Cell cycle progression was determined by flow cytometry of propidium iodide-stained cells, and DNA double strand break (DSB) induction and repair by γH2AX immunofluorescence. The radiosensitivity of mESCs was slightly higher compared to the murine osteoblast cell line OCT-1. The viability 72 h after X-irradiation decreased dose-dependently and was higher in the presence of leukemia inhibitory factor (LIF). Cells exposed to 2 or 7 Gy underwent a transient G2 arrest. X-irradiation induced γH2AX foci and they disappeared within 72 h. After 72 h of X-ray exposure, RNA was isolated and analyzed using genome-wide microarrays. The gene expression analysis revealed amongst others a regulation of developmental genes (Ada, Baz1a, Calcoco2, Htra1, Nefh, S100a6 and Rassf6), downregulation of genes involved in glycolysis and pyruvate metabolism whereas upregulation of genes related to the p53 signaling pathway. X-irradiated mESCs formed EBs and differentiated toward cardiomyocytes but their beating frequencies were lower compared to EBs from unirradiated cells. These results suggest that X-irradiation of mESCs deregulate genes related to the developmental process. The most significant biological processes found to be altered by X-irradiation in mESCs were the development of cardiovascular, nervous, circulatory and renal system. These results may explain the X-irradiation induced-embryonic lethality and malformations observed in animal studies.
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3
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Helm A, Arrizabalaga O, Pignalosa D, Schroeder IS, Durante M, Ritter S. Ionizing Radiation Impacts on Cardiac Differentiation of Mouse Embryonic Stem Cells. Stem Cells Dev 2016; 25:178-88. [PMID: 26506910 PMCID: PMC4733326 DOI: 10.1089/scd.2015.0260] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 10/27/2015] [Indexed: 12/14/2022] Open
Abstract
Little is known about the effects of ionizing radiation on the earliest stages of embryonic development although it is well recognized that ionizing radiation is a natural part of our environment and further exposure may occur due to medical applications. The current study addresses this issue using D3 mouse embryonic stem cells as a model system. Cells were irradiated with either X-rays or carbon ions representing sparsely and densely ionizing radiation and their effect on the differentiation of D3 cells into spontaneously contracting cardiomyocytes through embryoid body (EB) formation was measured. This study is the first to demonstrate that ionizing radiation impairs the formation of beating cardiomyocytes with carbon ions being more detrimental than X-rays. However, after prolonged culture time, the number of beating EBs derived from carbon ion irradiated cells almost reached control levels indicating that the surviving cells are still capable of developing along the cardiac lineage although with considerable delay. Reduced EB size, failure to downregulate pluripotency markers, and impaired expression of cardiac markers were identified as the cause of compromised cardiomyocyte formation. Dysregulation of cardiac differentiation was accompanied by alterations in the expression of endodermal and ectodermal markers that were more severe after carbon ion irradiation than after exposure to X-rays. In conclusion, our data show that carbon ion irradiation profoundly affects differentiation and thus may pose a higher risk to the early embryo than X-rays.
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Affiliation(s)
- Alexander Helm
- Biophysics Department, GSI Helmholtz Centre for Heavy Ion Research, Darmstadt, Germany
| | - Onetsine Arrizabalaga
- Biophysics Department, GSI Helmholtz Centre for Heavy Ion Research, Darmstadt, Germany
- IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
| | - Diana Pignalosa
- Biophysics Department, GSI Helmholtz Centre for Heavy Ion Research, Darmstadt, Germany
| | - Insa S. Schroeder
- Biophysics Department, GSI Helmholtz Centre for Heavy Ion Research, Darmstadt, Germany
| | - Marco Durante
- Biophysics Department, GSI Helmholtz Centre for Heavy Ion Research, Darmstadt, Germany
- Physics Department, Institute for Condensed Matter Physics, Technical University Darmstadt, Darmstadt, Germany
| | - Sylvia Ritter
- Biophysics Department, GSI Helmholtz Centre for Heavy Ion Research, Darmstadt, Germany
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4
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Kavanagh JN, Waring EJ, Prise KM. Radiation responses of stem cells: targeted and non-targeted effects. RADIATION PROTECTION DOSIMETRY 2015; 166:110-117. [PMID: 25877536 DOI: 10.1093/rpd/ncv161] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Stem cells are fundamental to the development of any tissue or organism via their ability to self-renew, which is aided by their unlimited proliferative capacity and their ability to produce fully differentiated offspring, often from multiple lineages. Stems cells are long lived and have the potential to accumulate mutations, including in response to radiation exposure. It is thought that stem cells have the potential to be induced into a cancer stem cell phenotype and that these may play an important role in resistance to radiotherapy. For radiation-induced carcinogenesis, the role of targeted and non-targeted effects is unclear with tissue or origin being important. Studies of genomic instability and bystander responses have shown consistent effects in haematopoietic models. Several models of radiation have predicted that stem cells play an important role in tumour initiation and that bystander responses could play a role in proliferation and self-renewal.
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Affiliation(s)
- J N Kavanagh
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7AE, UK
| | - E J Waring
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7AE, UK
| | - K M Prise
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7AE, UK
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5
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Sunaoshi M, Amasaki Y, Hirano-Sakairi S, Blyth BJ, Morioka T, Kaminishi M, Shang Y, Nishimura M, Shimada Y, Tachibana A, Kakinuma S. The effect of age at exposure on the inactivating mechanisms and relative contributions of key tumor suppressor genes in radiation-induced mouse T-cell lymphomas. Mutat Res 2015; 779:58-67. [PMID: 26141385 DOI: 10.1016/j.mrfmmm.2015.06.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2015] [Revised: 05/15/2015] [Accepted: 06/07/2015] [Indexed: 06/04/2023]
Abstract
Children are considered more sensitive to radiation-induced cancer than adults, yet any differences in genomic alterations associated with age-at-exposure and their underlying mechanisms remain unclear. We assessed genome-wide DNA copy number and mutation of key tumor suppressor genes in T-cell lymphomas arising after weekly irradiation of female B6C3F1 mice with 1.2Gy X-rays for 4 consecutive weeks starting during infancy (1 week old), adolescence (4 weeks old) or as young adults (8 weeks old). Although T-cell lymphoma incidence was similar, loss of heterozygosity at Cdkn2a on chromosome 4 and at Ikaros on chromosome 11 was more frequent in the two older groups, while loss at the Pten locus on chromosome 19 was more frequent in the infant-irradiated group. Cdkn2a and Ikaros mutation/loss was a common feature of the young adult-irradiation group, with Ikaros frequently (50%) incurring multiple independent hits (including deletions and mutations) or suffering a single hit predicted to result in a dominant negative protein (such as those lacking exon 4, an isoform we have designated Ik12, which lacks two DNA binding zinc-finger domains). Conversely, Pten mutations were more frequent after early irradiation (60%) than after young adult-irradiation (30%). Homozygous Pten mutations occurred without DNA copy number change after irradiation starting in infancy, suggesting duplication of the mutated allele by chromosome mis-segregation or mitotic recombination. Our findings demonstrate that while deletions on chromosomes 4 and 11 affecting Cdkn2a and Ikaros are a prominent feature of young adult irradiation-induced T-cell lymphoma, tumors arising after irradiation from infancy suffer a second hit in Pten by mis-segregation or recombination. This is the first report showing an influence of age-at-exposure on genomic alterations of tumor suppressor genes and their relative involvement in radiation-induced T-cell lymphoma. These data are important for considering the risks associated with childhood exposure to radiation.
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Affiliation(s)
- Masaaki Sunaoshi
- Radiobiology for Children's Health Program, Research Center for Radiation Protection, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan; Department of Biological Sciences, College of Science, Ibaraki University, Bunkyo 2-1-1, Mito, Ibaraki 310-8512, Japan
| | - Yoshiko Amasaki
- Radiobiology for Children's Health Program, Research Center for Radiation Protection, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Shinobu Hirano-Sakairi
- Radiobiology for Children's Health Program, Research Center for Radiation Protection, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Benjamin J Blyth
- Radiobiology for Children's Health Program, Research Center for Radiation Protection, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Takamitsu Morioka
- Radiobiology for Children's Health Program, Research Center for Radiation Protection, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan; Radiation Effect Accumulation and Prevention Project, Fukushima Project Headquarters, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Mutsumi Kaminishi
- Radiobiology for Children's Health Program, Research Center for Radiation Protection, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Yi Shang
- Radiation Effect Accumulation and Prevention Project, Fukushima Project Headquarters, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Mayumi Nishimura
- Radiobiology for Children's Health Program, Research Center for Radiation Protection, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan; Radiation Effect Accumulation and Prevention Project, Fukushima Project Headquarters, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Yoshiya Shimada
- Radiobiology for Children's Health Program, Research Center for Radiation Protection, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan; Radiation Effect Accumulation and Prevention Project, Fukushima Project Headquarters, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Akira Tachibana
- Department of Biological Sciences, College of Science, Ibaraki University, Bunkyo 2-1-1, Mito, Ibaraki 310-8512, Japan
| | - Shizuko Kakinuma
- Radiobiology for Children's Health Program, Research Center for Radiation Protection, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan; Radiation Effect Accumulation and Prevention Project, Fukushima Project Headquarters, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan.
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6
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Pro-apoptotic gene regulation and its activation by gamma-irradiation in the Caribbean fruit fly, Anastrepha suspensa. Apoptosis 2015; 20:1-9. [PMID: 25433919 DOI: 10.1007/s10495-014-1055-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Transcriptional activation of pro-apoptotic genes in response to cytotoxic stimuli is a conserved feature of the cell death pathway in metazoans. However, understanding the extent of this conservation in insects has been limited by the lack of known pro-apoptotic genes in non-drosophilids. Recently, we described the pro-apoptotic genes, Asrpr and Ashid, from the tephritid, Anastrepha suspensa, that now allow us to explore the conservation of pro-apoptotic gene regulation between a tephritid and drosophilids. In this study, we determined the developmental profiles of Asrpr and Ashid transcripts during embryogenesis and in embryos exposed to γ-irradiation. Transcript levels of both genes determined by qRT-PCR were low throughout embryogenesis, with strong Ashid expression occurring during early to mid-embryogenesis and Asrpr expression peaking in late embryogenesis. This correlated to acridine orange stained apoptotic cells first appearing at 17 h and increasing over time. However, when irradiated at 16 h post-oviposition embryos exhibited significant levels of apoptosis consistent with strong induction of Asrpr and Ashid transcript levels by γ-irradiation in young embryos <24 h post-oviposition. Furthermore, embryos irradiated <24 h post-oviposition failed to hatch, those irradiated between 24 and 32 h had increased hatching rates, but between 48 and 72 h irradiation had no effect on egg hatching. This indicates a transition of embryos from an irradiation-sensitive to irradiation-resistance stage between 24 and 48 h. Throughout post-embryonic development, the two pro-apoptotic genes share similar patterns of up-regulated gene expression, which correlate to ecdysone-induced developmental events, especially during metamorphosis. Together these results provide the first direct evidence for a conserved molecular mechanism of the programmed cell death pathway in insects.
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7
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Grygoryev D, Dan C, Gauny S, Eckelmann B, Ohlrich AP, Connolly M, Lasarev M, Grossi G, Kronenberg A, Turker MS. Autosomal mutants of proton-exposed kidney cells display frequent loss of heterozygosity on nonselected chromosomes. Radiat Res 2014; 181:452-63. [PMID: 24758577 DOI: 10.1667/rr13654.1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
High-energy protons found in the space environment can induce mutations and cancer, which are inextricably linked. We hypothesized that some mutants isolated from proton-exposed kidneys arose through a genome-wide incident that causes loss of heterozygosity (LOH)-generating mutations on multiple chromosomes (termed here genomic LOH). To test this hypothesis, we examined 11 pairs of nonselected chromosomes for LOH events in mutant cells isolated from the kidneys of mice exposed to 4 or 5 Gy of 1 GeV protons. The mutant kidney cells were selected for loss of expression of the chromosome 8-encoded Aprt gene. Genomic LOH events were also assessed in Aprt mutants isolated from isogenic cultured kidney epithelial cells exposed to 5 Gy of protons in vitro. Control groups were spontaneous Aprt mutants and clones isolated without selection from the proton-exposed kidneys or cultures. The in vivo results showed significant increases in genomic LOH events in the Aprt mutants from proton-exposed kidneys when compared with spontaneous Aprt mutants and when compared with nonmutant (i.e., nonselected) clones from the proton-exposed kidneys. A bias for LOH events affecting chromosome 14 was observed in the proton-induced Aprt mutants, though LOH for this chromosome did not confer increased radiation resistance. Genomic LOH events were observed in Aprt mutants isolated from proton-exposed cultured kidney cells; however the incidence was fivefold lower than in Aprt mutants isolated from exposed intact kidneys, suggesting a more permissive environment in the intact organ and/or the evolution of kidney clones prior to their isolation from the tissue. We conclude that proton exposure creates a subset of viable cells with LOH events on multiple chromosomes, that these cells form and persist in vivo, and that they can be isolated from an intact tissue by selection for a mutation on a single chromosome.
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Affiliation(s)
- Dmytro Grygoryev
- a Center for Research on Occupational and Environmental Toxicology (CROET), Oregon Health & Science University, Portland, Oregon 97239
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8
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Manda K, Kavanagh JN, Buttler D, Prise KM, Hildebrandt G. Low dose effects of ionizing radiation on normal tissue stem cells. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2014; 761:6-14. [PMID: 24566131 DOI: 10.1016/j.mrrev.2014.02.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 02/03/2014] [Accepted: 02/13/2014] [Indexed: 12/18/2022]
Abstract
In recent years, there has been growing evidence for the involvement of stem cells in cancer initiation. As a result of their long life span, stem cells may have an increased propensity to accumulate genetic damage relative to differentiated cells. Therefore, stem cells of normal tissues may be important targets for radiation-induced carcinogenesis. Knowledge of the effects of ionizing radiation (IR) on normal stem cells and on the processes involved in carcinogenesis is very limited. The influence of high doses of IR (>5Gy) on proliferation, cell cycle and induction of senescence has been demonstrated in stem cells. There have been limited studies of the effects of moderate (0.5-5Gy) and low doses (<0.5Gy) of IR on stem cells however, the effect of low dose IR (LD-IR) on normal stem cells as possible targets for radiation-induced carcinogenesis has not been studied in any depth. There may also be important parallels between stem cell responses and those of cancer stem cells, which may highlight potential key common mechanisms of their response and radiosensitivity. This review will provide an overview of the current knowledge of radiation-induced effects on normal stem cells, with particular focus on low and moderate doses of IR.
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Affiliation(s)
- Katrin Manda
- Department of Radiotherapy and Radiation Oncology, University of Rostock, Suedring 75, 18059 Rostock, Germany.
| | - Joy N Kavanagh
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, United Kingdom.
| | - Dajana Buttler
- Department of Radiotherapy and Radiation Oncology, University of Rostock, Suedring 75, 18059 Rostock, Germany.
| | - Kevin M Prise
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, United Kingdom.
| | - Guido Hildebrandt
- Department of Radiotherapy and Radiation Oncology, University of Rostock, Suedring 75, 18059 Rostock, Germany.
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9
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Luft S, Pignalosa D, Nasonova E, Arrizabalaga O, Helm A, Durante M, Ritter S. Fate of D3 mouse embryonic stem cells exposed to X-rays or carbon ions. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2014; 760:56-63. [PMID: 24397998 DOI: 10.1016/j.mrgentox.2013.12.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Revised: 12/23/2013] [Accepted: 12/24/2013] [Indexed: 01/06/2023]
Abstract
The risk of radiation exposure during embryonic development is still a major problem in radiotoxicology. In this study we investigated the response of the murine embryonic stem cell (mESC) line D3 to two radiation qualities: sparsely ionizing X-rays and densely ionizing carbon ions. We analyzed clonogenic cell survival, proliferation, induction of chromosome aberrations as well as the capability of cells to differentiate to beating cardiomyocytes up to 3 days after exposure. Our results show that, for all endpoints investigated, carbon ions are more effective than X-rays at the same radiation dose. Additionally, in long term studies (≥8 days post-irradiation) chromosomal damage and the pluripotency state were investigated. These studies reveal that pluripotency markers are present in the progeny of cells surviving the exposure to both radiation types. However, only in the progeny of X-ray exposed cells the aberration frequency was comparable to that of the control population, while the progeny of carbon ion irradiated cells harbored significantly more aberrations than the control, generally translocations. We conclude that cells surviving the radiation exposure maintain pluripotency but may carry stable chromosomal rearrangements after densely ionizing radiation.
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Affiliation(s)
- S Luft
- Biophysics Department, GSI Helmholtz Centre for Heavy Ion Research, Planckstraße 1, 64291 Darmstadt, Germany
| | - D Pignalosa
- Biophysics Department, GSI Helmholtz Centre for Heavy Ion Research, Planckstraße 1, 64291 Darmstadt, Germany
| | - E Nasonova
- Biophysics Department, GSI Helmholtz Centre for Heavy Ion Research, Planckstraße 1, 64291 Darmstadt, Germany; Laboratory of Radiation Biology, Joint Institute for Nuclear Research, Joliot-Curie 6, 141980 Dubna, Moscow Region, Russia
| | - O Arrizabalaga
- Biophysics Department, GSI Helmholtz Centre for Heavy Ion Research, Planckstraße 1, 64291 Darmstadt, Germany
| | - A Helm
- Biophysics Department, GSI Helmholtz Centre for Heavy Ion Research, Planckstraße 1, 64291 Darmstadt, Germany
| | - M Durante
- Biophysics Department, GSI Helmholtz Centre for Heavy Ion Research, Planckstraße 1, 64291 Darmstadt, Germany
| | - S Ritter
- Biophysics Department, GSI Helmholtz Centre for Heavy Ion Research, Planckstraße 1, 64291 Darmstadt, Germany.
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Kim TM, Rebel VI, Hasty P. Defining a genotoxic profile with mouse embryonic stem cells. Exp Biol Med (Maywood) 2013; 238:285-93. [PMID: 23598974 DOI: 10.1177/1535370213480700] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Many genotoxins are found in the environment from synthetic to natural, yet very few have been studied in depth. This means we fail to understand many molecules that damage DNA, we do not understand the type of damage they cause and the repair pathways required to correct their lesions. It is surprising so little is known about the vast majority of genotoxins since they have potential to cause disease from developmental defects to cancer to degenerative ailments. By contrast, some of these molecules have commercial and medical potential and some can be weaponized. Therefore, we need a systematic method to efficiently generate a genotoxic profile for these agents. A genotoxic profile would include the type of damage the genotoxin causes, the pathways used to repair the damage and the resultant mutations if repair fails. Mouse embryonic stem (ES) cells are well suited for identifying pathways and mutations. Mouse ES cells are genetically tractable and many DNA repair mutant cells are available. ES cells have a high mitotic index and form colonies so experiments can be completed quickly and easily. Furthermore, ES cells have robust DNA repair pathways to minimize genetic mutations at a particularly vulnerable time in life, early development when a mutation in a single cell could ultimately contribute to a large fraction of the individual. After an initial screen, other types of cells and mouse models can be used to complement the analysis. This review discusses the merging field of genotoxic screens in mouse ES cells that can be used to discover and study potential genotoxic activity for chemicals commonly found in our environment.
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Affiliation(s)
- Tae Moon Kim
- Department of Molecular Medicine and Institute of Biotechnology, University of Texas Health Science Center, San Antonio, TX 78245, USA
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11
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Nouspikel T. Genetic instability in human embryonic stem cells: prospects and caveats. Future Oncol 2013; 9:867-77. [DOI: 10.2217/fon.13.22] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Human embryonic stem cells (hESCs) display a leaky G1/S checkpoint and inefficient nucleotide excision repair activity. Maintenance of genomic stability in these cells mostly relies on the elimination of damaged cells by high rates of apoptosis. However, a subpopulation survives and proliferates actively, bypassing DNA damage by translesion synthesis, a known mutagenic process. Indeed, high levels of damage-induced mutations were observed in hESCs, similar to those in repair-deficient cells. The surviving cells also become more resistant to further damage, leading to a progressive enrichment of cultures in mutant cells. In long-term cultures, hESCs display features characteristic of neoplastic progression, including chromosomal anomalies often similar to those observed in embryo carcinoma. The implication of these facts for stem cell-based therapy and cancer research are discussed.
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Affiliation(s)
- Thierry Nouspikel
- Institute for Cancer Studies, University of Sheffield, Beech Hill Road, Sheffield, S10 2RX, UK
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12
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Turker MS, Grygoryev D, Dan C, Eckelmann B, Lasarev M, Gauny S, Kwoh E, Kronenberg A. Autosomal mutations in mouse kidney epithelial cells exposed to high-energy protons in vivo or in culture. Radiat Res 2013; 179:521-9. [PMID: 23560630 DOI: 10.1667/rr3174.1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Proton exposure induces mutations and cancer, which are presumably linked. Because protons are abundant in the space environment and significant uncertainties exist for the effects of space travel on human health, the purpose of this study was to identify the types of mutations induced by exposure of mammalian cells to 4-5 Gy of 1 GeV protons. We used an assay that selects for mutations affecting the chromosome 8-encoded Aprt locus in mouse kidney cells and selected mutants after proton exposure both in vivo and in cell culture. A loss of heterozygosity (LOH) assay for DNA preparations from the in vivo-derived kidney mutants revealed that protons readily induced large mutational events. Fluorescent in situ hybridization painting for chromosome 8 showed that >70% of proton-induced LOH patterns resembling mitotic recombination were in fact the result of nonreciprocal chromosome translocations, thereby demonstrating an important role for DNA double-strand breaks in proton mutagenesis. Large interstitial deletions, which also require the formation and resolution of double-strand breaks, were significantly induced in the cell culture environment (14% of all mutants), but to a lesser extend in vivo (2% of all mutants) suggesting that the resolution of proton-induced double-strand breaks can differ between the intact tissue and cell culture microenvironments. In total, the results demonstrate that double-strand break formation is a primary determinant for proton mutagenesis in epithelial cell types and suggest that resultant LOH for significant genomic regions play a critical role in proton-induced cancers.
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Affiliation(s)
- Mitchell S Turker
- Center for Research on Occupational and Environmental Toxicology CROET, Oregon Health & Science University, Portland, Oregon 97239, USA.
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13
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Sverdlov ED, Mineev K. Mutation rate in stem cells: an underestimated barrier on the way to therapy. Trends Mol Med 2013; 19:273-80. [PMID: 23481596 DOI: 10.1016/j.molmed.2013.01.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Revised: 01/15/2013] [Accepted: 01/24/2013] [Indexed: 12/23/2022]
Abstract
Stem cells (SCs) are thought to have great therapeutic potential, but due to continuously and stochastically arising new mutations that unpredictably change the composition of a cell population, the large-scale manufacturing of SCs with uniform properties and predictable behavior is a challenge. Quantitative evaluation of the characteristic mutation rate of a given stem cell line could be an important criterion in making the decision to use the line in medical practice. Such an evaluation could provide a new quality standard for newly derived human embryonic stem cell (hESC) lines prior to depositing them in stem cell banks. Here, we substantiate this view with simple calculations showing the effect of the mutation rate on changes in the cell population composition due to amplification. Selection of SCs with low mutation rate could reduce the risk of negative side effects during treatment.
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Affiliation(s)
- Eugene D Sverdlov
- Institute of Molecular Genetics, Russian Academy of Sciences, 2 Kurchatov Sq., Moscow, 123182, Russia.
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14
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Denissova NG, Nasello CM, Yeung PL, Tischfield JA, Brenneman MA. Resveratrol protects mouse embryonic stem cells from ionizing radiation by accelerating recovery from DNA strand breakage. Carcinogenesis 2011; 33:149-55. [PMID: 22049530 DOI: 10.1093/carcin/bgr236] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Resveratrol has elicited many provocative anticancer effects in laboratory animals and cultured cells, including reduced levels of oxidative DNA damage, inhibition of tumor initiation and progression and induction of apoptosis in tumor cells. Use of resveratrol as a cancer-preventive agent in humans will require that its anticancer effects not be accompanied by damage to normal tissue stem or progenitor cells. In mouse embryonic stem cells (mESC) or early mouse embryos exposed to ethanol, resveratrol has been shown to suppress apoptosis and promote survival. However, in cells exposed to genotoxic stress, survival may come at the expense of genome stability. To learn whether resveratrol can protect stem cells from DNA damage and to study its effects on genomic integrity, we exposed mESC pretreated with resveratrol to ionizing radiation (IR). Forty-eight hours pretreatment with a comparatively low concentration of resveratrol (10 μM) improved survival of mESC >2-fold after exposure to 5 Gy of X-rays. Cells pretreated with resveratrol sustained the same levels of reactive oxygen species and DNA strand breakage after IR as mock-treated controls, but repaired DNA damage more rapidly and resumed cell division sooner. Frequencies of IR-induced mutation at a chromosomal reporter locus were not increased in cells pretreated with resveratrol as compared with controls, indicating that resveratrol can improve viability in mESC after DNA damage without compromising genomic integrity.
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Affiliation(s)
- Natalia G Denissova
- Department of Genetics and Human Genetics Institute of New Jersey, Rutgers University, 145 Bevier Road, Piscataway, NJ 08854, USA
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