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Marchetti F, Douglas GR, Yauk CL. A Return to the Origin of the EMGS: Rejuvenating the Quest for Human Germ Cell Mutagens and Determining the Risk to Future Generations. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2020; 61:42-54. [PMID: 31472026 DOI: 10.1002/em.22327] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 08/21/2019] [Accepted: 08/28/2019] [Indexed: 05/23/2023]
Abstract
Fifty years ago, the Environmental Mutagen Society (now Environmental Mutagenesis and Genomics Society) was founded with a laser-focus on germ cell mutagenesis and the protection of "our most vital assets"-the sperm and egg genomes. Yet, five decades on, despite the fact that many agents have been demonstrated to induce inherited changes in the offspring of exposed laboratory rodents, there is no consensus on whether human germ cell mutagens exist. We argue that it is time to reevaluate the available data and conclude that we already have evidence for the existence of environmental exposures that impact human germ cells. What is missing are definite data to demonstrate a significant increase in de novo mutations in the offspring of exposed parents. We believe that with over two decades of research advancing knowledge and technologies in genomics, we are at the cusp of generating data to conclusively show that environmental exposures cause heritable de novo changes in the human offspring. We call on the research community to harness our technologies, synergize our efforts, and return to our Founders' original focus. The next 50 years must involve collaborative work between clinicians, epidemiologists, genetic toxicologists, genomics experts and bioinformaticians to precisely define how environmental exposures impact germ cell genomes. It is time for the research and regulatory communities to prepare to interpret the coming outpouring of data and develop a framework for managing, communicating and mitigating the risk of exposure to human germ cell mutagens. Environ. Mol. Mutagen. 61:42-54, 2020. © 2019 Her Majesty the Queen in Right of Canada.
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Affiliation(s)
- Francesco Marchetti
- Environmental Health Science Research Bureau, Health Canada, Ottawa, Ontario, Canada
| | - George R Douglas
- Environmental Health Science Research Bureau, Health Canada, Ottawa, Ontario, Canada
| | - Carole L Yauk
- Environmental Health Science Research Bureau, Health Canada, Ottawa, Ontario, Canada
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Wang M, Hearon SE, Johnson NM, Phillips TD. Development of broad-acting clays for the tight adsorption of benzo[a]pyrene and aldicarb. APPLIED CLAY SCIENCE 2019; 168:196-202. [PMID: 31435120 PMCID: PMC6703832 DOI: 10.1016/j.clay.2018.11.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
People and animals can be unintentionally exposed to complex mixtures of hazardous chemicals that can threaten the safety of food and water supplies following natural and man-made disasters and emergencies. Our research has focused on the development of broad-acting adsorbents that will tightly bind environmental contaminants in the gastrointestinal tract and decrease their bioavailability to humans and animals during these events. In this study, benzo[a]pyrene (BaP) and aldicarb were used as representative chemicals due to their high toxicity and extensive distribution in the environment. Both chemicals have been commonly detected in water and sediments in the US, and their distribution and concentrations can be enhanced during disasters. To address this problem, we have amended and functionalized montmorillonite clays with the nutrients, L-carnitine and choline to enhance their attraction for lipophilic toxins, such as BaP and aldicarb. Based on equilibrium isothermal analyses, we have demonstrated a significantly increased binding capacity (Qmax) and affinity (Kd) for BaP and aldicarb compared to the parent clay. Adsorption isotherms also showed that talc bound strongly to BaP with the highest Qmax, which was twice that of activated carbon. Additionally, cultures of adult hydra with a metabolism activation package were used as an in vivo toxicity indicator to confirm the ability of test adsorbents to protect against toxicity at low inclusion levels. We anticipate that the optimal adsorbents developed can be delivered in food and flavored water, or administered by sachet or capsule during emergencies and disasters to decrease human and animals exposures to environmental toxins.
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Affiliation(s)
- Meichen Wang
- Veterinary Integrative Biosciences Department, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
| | - Sara E. Hearon
- Veterinary Integrative Biosciences Department, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
| | - Natalie M. Johnson
- Environmental and Occupational Health, School of Public Health, Texas A&M University, College Station, TX 77843, USA
| | - Timothy D. Phillips
- Veterinary Integrative Biosciences Department, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
- Corresponding author.
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Rowan-Carroll A, Beal MA, Williams A, Marchetti F, Yauk CL. Dose-response mutation and spectrum analyses reveal similar responses at two microsatellite loci in benzo(a)pyrene-exposed mouse spermatogonia. Mutagenesis 2018; 32:463-470. [PMID: 28575466 DOI: 10.1093/mutage/gex008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Accepted: 03/23/2017] [Indexed: 11/14/2022] Open
Abstract
Identifying chemical exposures that can cause germline mutations is important as these mutations can be inherited, impacting both individual and population health. However, germline mutations are extremely rare and difficult to detect. Chemically induced germline mutations can be detected through analysis of highly unstable tandem repeat DNA. We recently developed a single-molecule PCR (SM-PCR) approach to quantify mutations at a mouse microsatellite locus (Mm2.2.1) in sperm for such purposes. In this study, we refine this approach through the combined analysis of mouse microsatellites Mm2.2.1 and Mm19.2.3. Mice were exposed to 0, 25, 50 or 100 mg/kg/day benzo(a)pyrene (BaP) by oral gavage for 28 days and sperm sampled 42 days after the end of exposure to measure effects on dividing spermatogonia. DNA was diluted to a single genome per PCR well for amplification of microsatellites in singleplex and multiplex reactions, and alleles were sized to identify mutations using capillary electrophoresis. Analysis of ~300-500 molecules per animal at both microsatellite loci, when tested individually, showed a ~2-fold increase in mutations relative to the controls at both the 50 and 100 mg/kg/day BaP doses. Multiplex SM-PCR revealed similar increases in mutation frequencies in both microsatellites. Comparison with results from a previous lacZ mutation assay conducted on the same mice revealed that although microsatellite mutations are a sensitive endpoint for detecting changes in mutation frequencies at lower doses, they appear to be saturable and thus have a reduced dynamic range. These results confirm that BaP is a male germ cell mutagen that broadly impacts tandem repeat DNA. Likewise, addition of a second hypervariable microsatellite increases the sensitivity of this assay.
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Affiliation(s)
- Andrea Rowan-Carroll
- Mechanistic Studies Division, Environmental Health Science and Research Bureau, Health Canada, Ottawa, Ontario K1A 0K9, Canada
| | - Marc A Beal
- Mechanistic Studies Division, Environmental Health Science and Research Bureau, Health Canada, Ottawa, Ontario K1A 0K9, Canada
| | - Andrew Williams
- Biostatistics and Epidemiology Division, Environmental Health Science and Research Bureau, Health Canada, Ottawa, Ontario, Canada
| | - Francesco Marchetti
- Mechanistic Studies Division, Environmental Health Science and Research Bureau, Health Canada, Ottawa, Ontario K1A 0K9, Canada
| | - Carole L Yauk
- Mechanistic Studies Division, Environmental Health Science and Research Bureau, Health Canada, Ottawa, Ontario K1A 0K9, Canada
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Aoki Y. Evaluation of in vivo mutagenesis for assessing the health risk of air pollutants. Genes Environ 2017; 39:16. [PMID: 28373898 PMCID: PMC5376282 DOI: 10.1186/s41021-016-0064-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2016] [Accepted: 12/06/2016] [Indexed: 11/16/2022] Open
Abstract
Various kind of chemical substances, including man-made chemical products and unintended products, are emitted to ambient air. Some of these substances have been shown to be mutagenic and therefore to act as a carcinogen in humans. National pollutant inventories (e.g., Pollutant Release and Transfer Registration in Japan) have estimated release amounts of man-made chemical products, but a major concern is the release of suspended particulate matter containing potent mutagens, for example, polycyclic aromatic hydrocarbons and related compounds generated by the combustion of fossil fuel, which are not estimated by PRTR system. In situ exposure studies have revealed that DNA adducts in the lung, and possibly mutations in germline cells are induced in rodents by inhalation of ambient air, indicating that evaluating in vivo mutations is important for assessing environmental health risks. Transgenic rodent systems (Muta, Big Blue, and gpt delta) are good tools for analyzing in vivo mutations induced by a mixture of chemical substances present in the environment. Following inhalation of diesel exhaust (used as a model mixture), mutation frequency was increased in the lung of gpt delta mice and base substitutions were induced at specific guanine residues (mutation hotspots) on the target transgenes. Mutation hotspots induced by diesel exhaust were different from those induced by benzo[a]pyrene, a typical mutagen in ambient air, but nearly identical to those induced by 1,6-dinitropyrene contained in diesel exhaust. Comparison between mutation hotspots in the TP53 (p53) gene in human lung cancer (data extracted from the IARC TP53 database) and mutations we identified in gpt delta mice showed that G to A transitions centered in CGT and CGG trinucleotides were mutation hotspots on both TP53 genes in human lung cancers and gpt genes in transgenic mice that inhaled diesel exhaust. The carcinogenic potency (TD50 value) of genotoxic carcinogen was shown to be correlated with the in vivo mutagenicity (total dose per increased mutant frequency). These results suggest that the mutations identified in transgenic rodents can help identify environmental mutagens that cause cancer.
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Affiliation(s)
- Yasunobu Aoki
- National Institute for Environmental Studies, Center for Health and Environmental Risk Research, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506 Japan
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Ling X, Zhang G, Sun L, Wang Z, Zou P, Gao J, Peng K, Chen Q, Yang H, Zhou N, Cui Z, Zhou Z, Liu J, Cao J, Ao L. Polycyclic aromatic hydrocarbons exposure decreased sperm mitochondrial DNA copy number: A cross-sectional study (MARHCS) in Chongqing, China. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2017; 220:680-687. [PMID: 27751638 DOI: 10.1016/j.envpol.2016.10.026] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 10/08/2016] [Accepted: 10/09/2016] [Indexed: 06/06/2023]
Abstract
Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental pollutants that have adverse effects on the male reproductive function. Many studies have confirmed that PAHs preferentially accumulate in mitochondria DNA relative to nuclear DNA and disrupt mitochondrial functions. However, it is rare whether exposure to PAHs is associated with mitochondrial damage and dysfunction in sperm. To evaluate the effects of PAHs on sperm mitochondria, we measured mitochondrial membrane potential (MMP), mitochondrial DNA copy number (mtDNAcn) and mtDNA integrity in 666 individuals from the Male Reproductive Health in Chongqing College Students (MARHCS) study. PAHs exposure was estimated by measuring eight urinary PAH metabolites (1-OHNap, 2-OHNap, 1-OHPhe, 2-OHPhe, 3-OHPhe, 4-OHPhe, 2-OHFlu and 1-OHPyr). The subjects were divided into low, median and high exposure groups using the tertile levels of urinary PAH metabolites. In univariate analyses, the results showed that increased levels of 2-OHPhe, 3-OHPhe, ∑Phe metabolites and 2-OHFlu were found to be associated with decreased sperm mtDNAcn. After adjusting for potential confounders, significantly negative associations of these metabolites remained (p = 0.039, 0.012, 0.01, 0.035, respectively). Each 1 μg/g creatinine increase in 2-OHPhe, 3-OHPhe, ∑Phe metabolites and 2-OHFlu was associated with a decrease in sperm mtDNAcn of 9.427%, 11.488%, 9.635% and 11.692%, respectively. There were no significant associations between urinary PAH metabolites and sperm MMP or mtDNA integrity. The results indicated that the low exposure levels of PAHs can cause abnormities in sperm mitochondria.
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Affiliation(s)
- Xi Ling
- Institute of Toxicology, College of Preventive Medicine, Third Military Medical University, Chongqing, China
| | - Guowei Zhang
- Institute of Toxicology, College of Preventive Medicine, Third Military Medical University, Chongqing, China
| | - Lei Sun
- Institute of Toxicology, College of Preventive Medicine, Third Military Medical University, Chongqing, China
| | - Zhi Wang
- Institute of Toxicology, College of Preventive Medicine, Third Military Medical University, Chongqing, China
| | - Peng Zou
- Institute of Toxicology, College of Preventive Medicine, Third Military Medical University, Chongqing, China
| | - Jianfang Gao
- Institute of Toxicology, College of Preventive Medicine, Third Military Medical University, Chongqing, China
| | - Kaige Peng
- Institute of Toxicology, College of Preventive Medicine, Third Military Medical University, Chongqing, China
| | - Qing Chen
- Institute of Toxicology, College of Preventive Medicine, Third Military Medical University, Chongqing, China
| | - Huan Yang
- Institute of Toxicology, College of Preventive Medicine, Third Military Medical University, Chongqing, China
| | - Niya Zhou
- Institute of Toxicology, College of Preventive Medicine, Third Military Medical University, Chongqing, China
| | - Zhihong Cui
- Institute of Toxicology, College of Preventive Medicine, Third Military Medical University, Chongqing, China
| | - Ziyuan Zhou
- Department of Environmental Health, College of Preventive Medicine, Third Military Medical University, Chongqing, China
| | - Jinyi Liu
- Institute of Toxicology, College of Preventive Medicine, Third Military Medical University, Chongqing, China
| | - Jia Cao
- Institute of Toxicology, College of Preventive Medicine, Third Military Medical University, Chongqing, China
| | - Lin Ao
- Institute of Toxicology, College of Preventive Medicine, Third Military Medical University, Chongqing, China.
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O'Brien JM, Beal MA, Yauk CL, Marchetti F. Next generation sequencing of benzo(a)pyrene-induced lacZ mutants identifies a germ cell-specific mutation spectrum. Sci Rep 2016; 6:36743. [PMID: 27829668 PMCID: PMC5103183 DOI: 10.1038/srep36743] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Accepted: 10/14/2016] [Indexed: 12/19/2022] Open
Abstract
De novo mutations are implicated in a variety of genetic diseases and arise primarily in the male germline. We investigated whether male germ cells have unique mechanisms for spontaneous or chemically-induced mutation relative to somatic cells using the MutaMouse model. We recovered lacZ transgenes from sperm 42 days after a 28-day exposure to benzo(a)pyrene (BaP, 100 mg/kg/day) to assess mutations arising in dividing spermatogonia. BaP caused a 3.4-fold increase in lacZ mutant frequency over controls which increased to 4.1-fold after clonal correction. We then used next generation sequencing to compare the spontaneous and BaP-induced mutation spectra in sperm and bone marrow. The spontaneous spectrum in sperm had significantly more G:C to A:T transitions and fewer mutations at A:T basepairs than bone marrow. BaP predominantly induced G:C to T:A transversions in both cell types, and both were enriched for mutations at CpG dinucleotides. However, BaP induced significantly more deletions in sperm, but more G:C to A:T transitions and G:C to C:G transversions in bone marrow. Differences in error-prone translesion DNA synthesis polymerases may underlie the observed spectrum differences between sperm and bone marrow. These findings suggest that mutations in sperm can arise via mechanisms that are unique to male germ cells.
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Affiliation(s)
- Jason M O'Brien
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, ON, K1A 0K9, Canada
| | - Marc A Beal
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, ON, K1A 0K9, Canada
| | - Carole L Yauk
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, ON, K1A 0K9, Canada
| | - Francesco Marchetti
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, ON, K1A 0K9, Canada
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Patel B, Das SK, Patri M. Neonatal Benzo[a]pyrene Exposure Induces Oxidative Stress and DNA Damage Causing Neurobehavioural Changes during the Early Adolescence Period in Rats. Dev Neurosci 2016; 38:150-62. [DOI: 10.1159/000446276] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Accepted: 04/18/2016] [Indexed: 11/19/2022] Open
Abstract
Humans are exposed to polycyclic aromatic hydrocarbons (PAHs) by ingestion of contaminated food and water. Prenatal exposure to benzo[a]pyrene (B[a]P) like PAHs through the placental barrier and neonatal exposure by breast milk and the environment may affect early brain development. In the present study, single intracisternal administration of B[a]P (0.2 and 2.0 µg/kg body weight) to male Wistar rat pups at postnatal day 5 (PND5) was carried out to study its specific effect on neonatal brain development and its consequences at PND30. B[a]P administration showed a significant increase in exploratory and anxiolytic-like behaviour with elevated hippocampal lipid peroxidation and protein oxidation at PND30. Further, DNA damage was estimated in vitro (Neuro2a and C6 cell lines) by the comet assay, and oxidative DNA damage of hippocampal sections was measured in vivo following exposure to B[a]P. DNA strand breaks (single and double) significantly increased due to B[a]P at PND30 in hippocampal neurons and increased the nuclear tail moment in Neuro2a cells. Hippocampal 8-oxo-2′-deoxyguanosine production was significantly elevated showing expression of more TUNEL-positive cells in both doses of B[a]P. Histological studies also revealed a significant reduction in mean area and perimeter of hippocampal neurons in rats treated with B[a]P 2.0 μg/kg, when compared to naïve and control rats. B[a]P significantly increased anxiolytic-like behaviour and oxidative DNA damage in the hippocampus causing apoptosis that may lead to neurodegeneration in adolescence. The findings of the present study address the potential role of B[a]P in inducing oxidative stress-mediated neurodegeneration in the hippocampus through oxidative DNA damage in the early adolescence period of rats.
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O'Brien JM, Beal MA, Yauk CL, Marchetti F. Benzo(a)pyrene Is Mutagenic in Mouse Spermatogonial Stem Cells and Dividing Spermatogonia. Toxicol Sci 2016; 152:363-71. [PMID: 27208087 PMCID: PMC4960908 DOI: 10.1093/toxsci/kfw088] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Although many environmental agents are established male germ cell mutagens, few are known to induce mutations in spermatogonial stem cells. Stem cell mutations are of great concern because they result in a permanent increase in the number of mutations carried in sperm. We investigated mutation induction during mouse spermatogenesis following exposure to benzo(a)pyrene (BaP). MutaMouse males were given 0, 12.5, 25, 50, or 100 mg/kg bw/day BaP for 28 days by oral gavage. Germ cells were collected from the cauda epididymis and seminiferous tubules 3 days after exposure and from cauda epididymis 42 and 70 days after exposure. This design enabled targeted investigation of effects on post-spermatogonia, dividing spermatogonia, and spermatogonial stem cells, respectively. BaP increased lacZ mutant frequency (MF) in cauda sperm after exposure of dividing spermatogonia (4.2-fold at highest dose, P < .01) and spermatogonial stem cells (2.1-fold at highest dose, P < .01). No significant increases in MF were detected in cauda sperm or seminiferous tubule cells collected 3 days post-exposure. Dose-response modelling suggested that the mutational response in male germ cells to BaP is sub-linear at low doses. Our results demonstrate that oral exposure to BaP causes spermatogonial stem cell mutations, that different phases of spermatogenesis exhibit varying sensitivities to BaP, with dividing spermatogonia representing a window of peak sensitivity, and that sampling spermatogenic cells from the seminiferous tubules at earlier time-points may underestimate germ cell mutagenicity. This information is critical to optimize the use of the international test guideline for transgenic rodent mutation assays for detecting germ cell mutagens.
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Affiliation(s)
- Jason M O'Brien
- *Environmental Health Science and Research Bureau, Health Canada, Ottawa, ON K1A 0K9, Canada
| | - Marc A Beal
- *Environmental Health Science and Research Bureau, Health Canada, Ottawa, ON K1A 0K9, Canada
| | - Carole L Yauk
- *Environmental Health Science and Research Bureau, Health Canada, Ottawa, ON K1A 0K9, Canada
| | - Francesco Marchetti
- *Environmental Health Science and Research Bureau, Health Canada, Ottawa, ON K1A 0K9, Canada
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Kryukov GV, Bielski CM, Samocha K, Fromer M, Seepo S, Gentry C, Neale B, Garraway LA, Sweeney CJ, Taplin ME, Van Allen EM. Genetic Effect of Chemotherapy Exposure in Children of Testicular Cancer Survivors. Clin Cancer Res 2015; 22:2183-9. [PMID: 26631610 DOI: 10.1158/1078-0432.ccr-15-2317] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 11/09/2015] [Indexed: 11/16/2022]
Abstract
PURPOSE Cancer survivors express anxiety that chemotherapy exposure may lead to transmissible genetic damage in posttreatment children. Preclinical models suggest that chemotherapy exposure may result in considerable genomic alterations in postexposure progeny. Epidemiologic studies have not demonstrated a significant increase in congenital abnormalities in posttreatment children of cancer survivors, but the inherited genome-wide effect of chemotherapy exposure in humans is unknown. EXPERIMENTAL DESIGN Two testicular cancer survivors cured with chemotherapy who had children pre- and postexposure without sperm banking were identified. Familial germline whole genome sequencing (WGS) was performed for these families, and analytic methods were utilized to identify de novo alterations, including mutations, recombinations, and structural rearrangements in the pre- and postexposure offspring. RESULTS No increase in de novo germline mutations in postexposure children compared with their preexposure siblings was found. Furthermore, there were no increased short insertion/deletions, recombination frequency, or structural rearrangements in these postexposure children. CONCLUSIONS In two families of male cancer survivors, there was no transmissible genomic impact of significant mutagenic exposure in postexposure children. This study may provide possible reassuring evidence for patients undergoing chemotherapy who are unable to have pretreatment sperm cryopreservation. Expanded cohorts that utilize WGS to identify environmental exposure effects on the inherited genome may inform the generalizability of these results. Clin Cancer Res; 22(9); 2183-9. ©2015 AACR.
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Affiliation(s)
- Gregory V Kryukov
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts. Division of Genetics, Brigham and Women's Hospital, Boston, Massachusetts. Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts
| | - Craig M Bielski
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts
| | - Kaitlin Samocha
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts. Analytical and Translational Genetics Unit, Massachusetts General Hospital, Boston, Massachusetts
| | - Menachem Fromer
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts. Analytical and Translational Genetics Unit, Massachusetts General Hospital, Boston, Massachusetts. Department of Genetics and Genomic Sciences, Mount Sinai School of Medicine, New York, New York. Department of Psychiatry, Mount Sinai School of Medicine, New York, New York
| | - Sara Seepo
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts
| | - Carleen Gentry
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts
| | - Benjamin Neale
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts. Analytical and Translational Genetics Unit, Massachusetts General Hospital, Boston, Massachusetts
| | - Levi A Garraway
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts. Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts
| | | | - Mary-Ellen Taplin
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts.
| | - Eliezer M Van Allen
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts. Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts.
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Beal MA, Rowan-Carroll A, Campbell C, Williams A, Somers CM, Marchetti F, Yauk CL. Single-molecule PCR analysis of an unstable microsatellite for detecting mutations in sperm of mice exposed to chemical mutagens. Mutat Res 2015; 775:26-32. [PMID: 25863182 DOI: 10.1016/j.mrfmmm.2015.03.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Revised: 03/16/2015] [Accepted: 03/22/2015] [Indexed: 12/15/2022]
Abstract
Single-molecule PCR (SM-PCR) analysis of long and repetitive DNA sequences, known as expanded simple tandem repeats (ESTRs), has been the most efficient method for studying germline mutation induction in endogenous sequences to date. However, the long length of these sequences makes mutation detection imprecise and laborious, and they have been characterized only in mice. Here, we explore the use of unstable microsatellite sequences that can be typed with high precision by capillary electrophoresis as alternative loci for detecting germline mutations. We screened 24 microsatellite loci across inbred mouse strains and identified Mm2.2.1 as the most polymorphic microsatellite locus. We then optimized SM-PCR of Mm2.2.1 to detect mutations in sperm. SM-PCR analysis of sperm from untreated B6C3F1 and Muta(™)Mouse samples revealed mutation frequencies that are consistent with rates derived from family pedigree analysis (∼ 5 × 10(-3)). To determine whether this locus can be used to detect chemically induced germline mutations, Muta(™)Mouse males were exposed by oral gavage to a single dose of 100mg/kg of N-ethyl-N-nitrosourea (ENU) or to 100mg/kg of benzo(a)pyrene (BaP) for 28 days alongside vehicle treated controls. Sperm were collected 10 weeks post-ENU exposure to sample sperm exposed as spermatogonial stem cells and 6 weeks post-BaP exposure to sample sperm that were dividing spermatogonia when the exposure was terminated. Both treatments resulted in a significant (approximately 2-fold) increase in mutation frequency in sperm compared to the control animals. The work establishes the utility of this microsatellite for studying mutation induction in the germ cells of mice. Because microsatellites are found in virtually every species, this approach holds promise for other organisms, including humans.
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Affiliation(s)
- Marc A Beal
- Carleton University, Ottawa, Ontario K1S 5B6, Canada; Environmental Health Science and Research Bureau, Healthy Environments and Consumer Safety Branch, Health Canada, Ottawa, Ontario K1A 0K9, Canada.
| | - Andrea Rowan-Carroll
- Environmental Health Science and Research Bureau, Healthy Environments and Consumer Safety Branch, Health Canada, Ottawa, Ontario K1A 0K9, Canada.
| | - Caleigh Campbell
- Environmental Health Science and Research Bureau, Healthy Environments and Consumer Safety Branch, Health Canada, Ottawa, Ontario K1A 0K9, Canada.
| | - Andrew Williams
- Environmental Health Science and Research Bureau, Healthy Environments and Consumer Safety Branch, Health Canada, Ottawa, Ontario K1A 0K9, Canada.
| | | | - Francesco Marchetti
- Environmental Health Science and Research Bureau, Healthy Environments and Consumer Safety Branch, Health Canada, Ottawa, Ontario K1A 0K9, Canada.
| | - Carole L Yauk
- Environmental Health Science and Research Bureau, Healthy Environments and Consumer Safety Branch, Health Canada, Ottawa, Ontario K1A 0K9, Canada.
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