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Takimoto N, Ishii Y, Mitsumoto T, Takasu S, Namiki M, Shibutani M, Ogawa K. Formation of hepatocyte cytoplasmic inclusions and their contribution to methylcarbamate-induced hepatocarcinogenesis in F344 rats. Toxicol Sci 2024; 198:40-49. [PMID: 38230821 DOI: 10.1093/toxsci/kfad131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2024] Open
Abstract
Methylcarbamate (MC), a reaction product between dimethyl dicarbonate and ammonia or ammonium ion, is a potent hepatocarcinogen in F344 rats. Various genotoxicity tests have shown negative results for MC. Although previous studies have described the effects of MC on the liver, including the formation of characteristic basophilic cytoplasmic inclusions (CIs) in hepatocytes, the toxicological significance of CIs and their involvement in hepatocarcinogenesis remain unclear. In the current study, to elucidate the mechanisms of MC hepatocarcinogenesis, we examined hepatotoxicity and genotoxicity after 4 weeks of administration of MC using gpt delta rats with an F344 genetic background as a reporter gene transgenic animal model. Histopathologically, single-cell necrosis, karyomegaly, and the formation of CIs positive for Feulgen staining were observed in hepatocytes at the carcinogenic dose, demonstrating the hepatotoxicity of MC. CIs were also detected as large micronuclei in liver micronucleus tests but not in the bone marrow, suggesting that MC could cause chromosomal instability specifically in the livers of rats. Reporter gene mutation assays demonstrated that MC did not induce mutagenicity even in the liver. Immunofluorescence analyses revealed that CIs exhibited loss of nuclear envelope integrity, increased heterochromatinization, and accumulation of DNA damage. An increase in liver STING protein levels suggested an effect on the cyclic GMP-AMP synthase/stimulator of interferon genes innate immune pathway. Overall, these data demonstrated the possible occurrence of chromothripsis-like chromosomal rearrangements via CIs. Thus, the formation of CIs could be a crucial event in the early stage of MC-induced hepatocarcinogenesis in F344 rats.
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Affiliation(s)
- Norifumi Takimoto
- Division of Pathology, National Institute of Health Sciences, Kawasaki-shi, Kanagawa 210-9501, Japan
- Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology, Fuchu-shi, Tokyo 183-8509, Japan
| | - Yuji Ishii
- Division of Pathology, National Institute of Health Sciences, Kawasaki-shi, Kanagawa 210-9501, Japan
| | - Tatsuya Mitsumoto
- Division of Pathology, National Institute of Health Sciences, Kawasaki-shi, Kanagawa 210-9501, Japan
- Faculty of Animal Health Technology, Yamazaki University of Animal Health Technology, Hachioji, Tokyo 192-0364, Japan
| | - Shinji Takasu
- Division of Pathology, National Institute of Health Sciences, Kawasaki-shi, Kanagawa 210-9501, Japan
| | - Moeka Namiki
- Division of Pathology, National Institute of Health Sciences, Kawasaki-shi, Kanagawa 210-9501, Japan
| | - Makoto Shibutani
- Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology, Fuchu-shi, Tokyo 183-8509, Japan
| | - Kumiko Ogawa
- Division of Pathology, National Institute of Health Sciences, Kawasaki-shi, Kanagawa 210-9501, Japan
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Castel R, Tassistro V, Claeys-Bruno M, Malleret L, Orsière T. In Vitro Genotoxicity Evaluation of PAHs in Mixtures Using Experimental Design. Toxics 2023; 11:toxics11050470. [PMID: 37235284 DOI: 10.3390/toxics11050470] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 05/11/2023] [Accepted: 05/16/2023] [Indexed: 05/28/2023]
Abstract
Settled dusts are sinks for environmental pollutants, including Polycyclic Aromatic Hydrocarbons (PAHs) that are ubiquitous, persistent, and carcinogenic. To assess their toxicity in mixtures, Toxic Equivalent Factors (TEFs) are routinely used and based on the hypothesis of additive effects, although PAH interactions may occur and remain an open issue. This study investigated genotoxic binary interaction effects for six PAHs in mixtures using two in vitro assays and estimated Genotoxic Equivalent Factors (GEFs) to roughly predict the genotoxicity of PAH in mixtures. The Design of the Experiment approach was used with the micronucleus assay for cytostasis and micronuclei frequency and the alkaline comet assay for DNA damage. GEFs were determined for each PAH independently and in a mixture. For the cytostasis endpoint, no PAHs interaction was noted. BbF and BaP had a synergistic effect on DNA damage. All the PAH interacted between them regarding chromosomal damage. Although the calculated GEFs were similar to the TEFs, the latter may underestimate the genotoxic potential of a PAH mixture. GEFs calculated for PAH alone were lower than GEFs for PAHs in mixtures; thus, mixtures induce greater DNA/chromosomal damage than expected. This research helps to advance the challenging issue of contaminant mixtures' effects on human health.
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Affiliation(s)
- Rebecca Castel
- Institut Méditerranéen de Biodiversité et Ecologie, Aix Marseille University, Avignon University, CNRS, IRD, IMBE, FR ECCOREV, ITEM, 13005 Marseille, France
- Laboratoire Chimie Environnement, Aix Marseille University, CNRS, LCE, FR ECCOREV, ITEM, 13545 Aix-en-Provence, France
| | - Virginie Tassistro
- Institut Méditerranéen de Biodiversité et Ecologie, Aix Marseille University, Avignon University, CNRS, IRD, IMBE, FR ECCOREV, ITEM, 13005 Marseille, France
| | - Magalie Claeys-Bruno
- Institut Méditerranéen de Biodiversité et Ecologie, Aix Marseille University, Avignon University, CNRS, IRD, IMBE, FR ECCOREV, ITEM, 13005 Marseille, France
| | - Laure Malleret
- Laboratoire Chimie Environnement, Aix Marseille University, CNRS, LCE, FR ECCOREV, ITEM, 13545 Aix-en-Provence, France
| | - Thierry Orsière
- Institut Méditerranéen de Biodiversité et Ecologie, Aix Marseille University, Avignon University, CNRS, IRD, IMBE, FR ECCOREV, ITEM, 13005 Marseille, France
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Cao Y, Xi J, Tang C, Yang Z, Liu W, You X, Feng N, Zhang XY, Wu J, Yu Y, Luan Y. PIG-A gene mutation as a genotoxicity biomaker in polycyclic aromatic hydrocarbon-exposed barbecue workers. Genes Environ 2021; 43:54. [PMID: 34879859 PMCID: PMC8656086 DOI: 10.1186/s41021-021-00230-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 11/28/2021] [Indexed: 01/02/2023] Open
Abstract
Background The PIG-A gene mutation assay is a valuable tool for measuring in vivo gene mutations in blood cells. The human PIG-A assay, used as a potential genotoxicity biomarker, is minimally invasive, sensitive, and cost-efficient; however, the relationship between carcinogen exposure and PIG-A mutations is not well understood. Methods We investigated the genotoxic effect of red blood cells using PIG-A assay and lymphocyte cytokinesis-block micronucleus test in barbecue restaurant workers (N = 70) exposed to polycyclic aromatic hydrocarbons (PAHs) and self-identified healthy control subjects (N = 56). Urinary PAH metabolites were measured to evaluate internal exposure levels. Results Multivariate Poisson regression showed that the PAH-exposed workers exhibited significantly higher PIG-A mutant frequency (MF) (8.04 ± 6.81 × 10− 6) than did the controls (5.56 ± 5.26 × 10− 6) (RR = 0.707, 95% CI: 0.615–0.812, P < 0.001). These results indicate that PAH exposure is a risk factor for elevated PIG-A MF. The frequencies of micronuclei (MN) and nuclear buds (NBUD) in the PAH-exposed workers (MN: 3.06 ± 2.07 ‰, NBUD: 1.38 ± 1.02 ‰) were also significantly higher than in the controls (MN: 1.46 ± 0.64 ‰, P < 0.001; NBUD: 0.70 ± 0.60 ‰, P < 0.001). Additionally, PIG-A MFs showed better associations with several urinary hydroxylated PAH metabolites (P2-OH-Flu = 0.032, r2-OH-Flu = 0. 268; P2-OH-Phe = 0.022, r2-OH-Phe = 0.286; P3-OH-Phe = 0.0312, r3-OH-Phe = 0.270; P4-OH-Phe = 0.018, r4-OH-Phe = 0.296), while the increase in MN, NPB, and NBUD frequencies was not associated with any OH-PAH metabolites; and high-PAH-exposed workers showed the highest PIG-A MFs. Furthermore, there was a significant association between PIG-A MF and PAH exposure levels (Chi-square test for trend, P = 0.006). Conclusions Our results indicate that an increase in PIG-A MF in barbecue workers could reflect the response to PAH exposure, providing evidence of its potential as a genotoxicity biomarker in human risk assessment. Supplementary Information The online version contains supplementary material available at 10.1186/s41021-021-00230-1.
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Affiliation(s)
- Yiyi Cao
- School of Public Health, Shanghai Jiaotong University School of Medicine, Shanghai, 200025, People's Republic of China
| | - Jing Xi
- School of Public Health, Shanghai Jiaotong University School of Medicine, Shanghai, 200025, People's Republic of China
| | - Chuanxi Tang
- Center for Disease Control and Prevention of the Changning District of Shanghai, Shanghai, 200051, People's Republic of China
| | - Ziying Yang
- Guangdong-Hong Kong-Macao Joint Laboratory for Contaminants Exposure and Health, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou, 510006, People's Republic of China.,Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, Key Laboratory of City Cluster Environmental Safety and Green Development, School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou, 510006, People's Republic of China
| | - Weiying Liu
- School of Public Health, Shanghai Jiaotong University School of Medicine, Shanghai, 200025, People's Republic of China
| | - Xinyue You
- School of Public Health, Shanghai Jiaotong University School of Medicine, Shanghai, 200025, People's Republic of China
| | - Nannan Feng
- School of Public Health, Shanghai Jiaotong University School of Medicine, Shanghai, 200025, People's Republic of China
| | - Xin Yu Zhang
- School of Public Health, Shanghai Jiaotong University School of Medicine, Shanghai, 200025, People's Republic of China
| | - Jingui Wu
- Center for Disease Control and Prevention of the Changning District of Shanghai, Shanghai, 200051, People's Republic of China
| | - Yingxin Yu
- Guangdong-Hong Kong-Macao Joint Laboratory for Contaminants Exposure and Health, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou, 510006, People's Republic of China.,Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, Key Laboratory of City Cluster Environmental Safety and Green Development, School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou, 510006, People's Republic of China
| | - Yang Luan
- School of Public Health, Shanghai Jiaotong University School of Medicine, Shanghai, 200025, People's Republic of China.
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Tu H, Yu C, Tong W, Zhou C, Li R, Huang P, Wang Q, Chang Y. Evaluation of the Liver and Blood Micronucleus, and Comet Assay Endpoints in a 14-Day Repeated Dose Study with Methyl Carbamate and 1, 3-Propane Sultone. Mutagenesis 2021; 36:401-406. [PMID: 34516639 DOI: 10.1093/mutage/geab034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Accepted: 09/12/2021] [Indexed: 11/12/2022] Open
Abstract
The repeated-dose liver micronucleus (RDLMN) assay is a novel method for detecting genotoxic chemicals. Two carcinogens methyl carbamate (MC) and 1, 3-propane sultone (PS) were evaluated for the liver micronucleus in a 14-day repeated-dose study with Sprague Dawley rats. Additionally, micronucleated reticulocytes (MN-RET) in peripheral blood and DNA damage (alkaline comet assay) in the liver were also assessed in the same animals. Ten groups of 5 male Sprague Dawley rats were treated once daily with MC (300, 600, or 1200 mg/kg/day), PS (37.5, 75, or 150 mg/kg/day), negative control, or 3 positive controls by oral gavage for 15 days. Blood samples were collected at 3 hours after the last administration for determining MN-RET frequencies (%MN-RET), and the livers were sampled for determining the frequency of micronuclei and DNA damage. MC was negative in the comet assay, liver micronucleus assay, and reticulocyte micronucleus assay, while PS was positive in all three assays. These results are consistent with the previous genotoxic findings of MC and PS. Therefore, the liver micronucleus assay can be effectively integrated into repeated dose studies in animals. Moreover, integration of multiple genotoxicity endpoints into one study can reduce the number of animals, boost the experimental efficiency, and provides a comprehensive evaluation of the genotoxic potential of chemicals.
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Affiliation(s)
- Honggang Tu
- School of Pharmacy, Shanghai Jiao Tong University, China.,Shanghai InnoStar Bio-Tech Co. Ltd/National Shanghai Center for New Drug Safety Evaluation and Research, China State Institute of Pharmaceutical Industry, Shanghai, China
| | - Chunrong Yu
- Shanghai InnoStar Bio-Tech Co. Ltd/National Shanghai Center for New Drug Safety Evaluation and Research, China State Institute of Pharmaceutical Industry, Shanghai, China
| | - Wen Tong
- Shanghai InnoStar Bio-Tech Co. Ltd/National Shanghai Center for New Drug Safety Evaluation and Research, China State Institute of Pharmaceutical Industry, Shanghai, China
| | - Changhui Zhou
- Shanghai InnoStar Bio-Tech Co. Ltd/National Shanghai Center for New Drug Safety Evaluation and Research, China State Institute of Pharmaceutical Industry, Shanghai, China
| | - Ruowan Li
- Shanghai InnoStar Bio-Tech Co. Ltd/National Shanghai Center for New Drug Safety Evaluation and Research, China State Institute of Pharmaceutical Industry, Shanghai, China
| | - Pengcheng Huang
- Shanghai InnoStar Bio-Tech Co. Ltd/National Shanghai Center for New Drug Safety Evaluation and Research, China State Institute of Pharmaceutical Industry, Shanghai, China
| | - Qingli Wang
- Center for Drug Evaluation, National Medical Products Administration (China Food and Drug Administration), Beijing, China
| | - Yan Chang
- Shanghai InnoStar Bio-Tech Co. Ltd/National Shanghai Center for New Drug Safety Evaluation and Research, China State Institute of Pharmaceutical Industry, Shanghai, China
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Johnson GE, Dobo K, Gollapudi B, Harvey J, Kenny J, Kenyon M, Lynch A, Minocherhomji S, Nicolette J, Thybaud V, Wheeldon R, Zeller A. Permitted daily exposure limits for noteworthy N-nitrosamines. Environ Mol Mutagen 2021; 62:293-305. [PMID: 34089278 DOI: 10.1002/em.22446] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 05/07/2021] [Accepted: 05/11/2021] [Indexed: 06/12/2023]
Abstract
A genotoxic carcinogen, N-nitrosodimethylamine (NDMA), was detected as a synthesis impurity in some valsartan drugs in 2018, and other N-nitrosamines, such as N-nitrosodiethylamine (NDEA), were later detected in other sartan products. N-nitrosamines are pro-mutagens that can react with DNA following metabolism to produce DNA adducts, such as O6 -alkyl-guanine. The adducts can result in DNA replication miscoding errors leading to GC>AT mutations and increased risk of genomic instability and carcinogenesis. Both NDMA and NDEA are known rodent carcinogens in male and female rats. The DNA repair enzyme, methylguanine DNA-methyltransferase can restore DNA integrity via the removal of alkyl groups from guanine in an error-free fashion and this can result in nonlinear dose responses and a point of departure or "practical threshold" for mutation at low doses of exposure. Following International recommendations (ICHM7; ICHQ3C and ICHQ3D), we calculated permissible daily exposures (PDE) for NDMA and NDEA using published rodent cancer bioassay and in vivo mutagenicity data to determine benchmark dose values and define points of departure and adjusted with appropriate uncertainty factors (UFs). PDEs for NDMA were 6.2 and 0.6 μg/person/day for cancer and mutation, respectively, and for NDEA, 2.2 and 0.04 μg/person/day. Both PDEs are higher than the acceptable daily intake values (96 ng for NDMA and 26.5 ng for NDEA) calculated by regulatory authorities using simple linear extrapolation from carcinogenicity data. These PDE calculations using a bench-mark approach provide a more robust assessment of exposure limits compared with simple linear extrapolations and can better inform risk to patients exposed to the contaminated sartans.
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Affiliation(s)
- George E Johnson
- Swansea University Medical School, Swansea University, Swansea, Wales, UK
| | - Krista Dobo
- Genetic Toxicology, Drug Safety Research and Development, Pfizer, Groton, Connecticut, USA
| | - Bhaskar Gollapudi
- Center for Toxicology and Mechanistic Biology, Exponent Consulting, Midland, Michigan, USA
| | | | | | - Michelle Kenyon
- Genetic Toxicology, Drug Safety Research and Development, Pfizer, Groton, Connecticut, USA
| | | | | | - John Nicolette
- Genetic, Environmental and Occupational Toxicology, AbbVie, Chicago, Illinois, USA
| | | | - Ryan Wheeldon
- Swansea University Medical School, Swansea University, Swansea, Wales, UK
| | - Andreas Zeller
- Pharmaceutical Sciences, pRED Innovation Center Basel, Hoffmann-La Roche Ltd, Basel, Switzerland
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Lawrence R, Haboubi H, Williams L, Doak S, Jenkins G. Dietary and lifestyle factors effect erythrocyte PIG-A mutant frequency in humans. Mutagenesis 2020; 35:geaa025. [PMID: 33043963 DOI: 10.1093/mutage/geaa025] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 09/07/2020] [Indexed: 01/22/2023] Open
Abstract
It is well understood that poor diet and lifestyle choices can increase the risk of cancer. It is also well documented that cancer is a disease of DNA mutations, with mutations in key genes driving carcinogenesis. Measuring these mutations in a minimally invasive way may be informative as to which exposures are harmful and thus allow us to introduce primary preventative measures, in a bid to reduce cancer incidences. Here, we have measured mutations in the phosphatidylinositol glycan class A (PIG-A) gene in erythrocytes from healthy volunteers (n = 156) and from non-cancer patients attending the local endoscopy department (n = 144). The X-linked PIG-A gene encodes an enzyme involved in glycosylphosphatidylinositol (GPI) anchor synthesis. A silencing mutation in which leads to the absence of GPI anchors on the extracellular surface which can be rapidly assessed using flow cytometry. The background level of PIG-A mutant erythrocytes was 2.95 (95% CI: 2.59-3.67) mutant cells (10-6). Older age increased mutant cell frequency (P < 0.001). There was no difference in mutant cell levels between males and females (P = 0.463) or smokers and non-smokers (P = 0.186). In the endoscopy group, aspirin users had lower mutant frequencies (P = 0.001). Further information on diet and exercise was available for the endoscopy patient group alone, where those with a higher health promotion index score had lower mutant frequencies (P = 0.011). Higher dietary intake of vegetables reduced mutant cell levels (P = 0.022). Participants who exercised for at least 1 h a week appeared to have reduced mutant frequencies than those who did not exercise, although this was not statistically significant (P = 0.099). This low background level of mutant erythrocytes in a population makes this assay an attractive tool to monitor exposures such as those associated with lifestyles and diet, as demonstrated here.
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Affiliation(s)
| | | | - Lisa Williams
- Department of Endoscopy, Swansea Bay University Health Board, Swansea, UK
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Maurice C, Dertinger SD, Yauk CL, Marchetti F. Integrated In Vivo Genotoxicity Assessment of Procarbazine Hydrochloride Demonstrates Induction of Pig-a and LacZ Mutations, and Micronuclei, in MutaMouse Hematopoietic Cells. Environ Mol Mutagen 2019; 60:505-512. [PMID: 30592561 PMCID: PMC6618172 DOI: 10.1002/em.22271] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 12/21/2018] [Accepted: 12/26/2018] [Indexed: 06/09/2023]
Abstract
Procarbazine hydrochloride (PCH) is a DNA-reactive hematopoietic carcinogen with potent and well-characterized clastogenic activity. However, there is a paucity of in vivo mutagenesis data for PCH, and in vitro assays often fail to detect the genotoxic effects of PCH due to the complexity of its metabolic activation. We comprehensively evaluated the in vivo genotoxicity of PCH on hematopoietic cells of male MutaMouse transgenic rodents using a study design that facilitated assessments of micronuclei and Pig-a mutation in circulating erythrocytes, and lacZ mutant frequencies in bone marrow. Mice were orally exposed to PCH (0, 6.25, 12.5, and 25 mg/kg/day) for 28 consecutive days. Blood samples collected 2 days after cessation of treatment exhibited significant dose-related induction of micronuclei in both immature and mature erythrocytes. Bone marrow and blood collected 3 and 70 days after cessation of treatment also showed significantly elevated mutant frequencies in both the lacZ and Pig-a assays even at the lowest dose tested. PCH-induced lacZ and Pig-a (immature and mature erythrocytes) mutant frequencies were highly correlated, with R2 values ≥0.956, with the exception of lacZ vs. Pig-a mutants in mature erythrocytes at the 70-day time point (R2 = 0.902). These results show that PCH is genotoxic in vivo and demonstrate that the complex metabolism and resulting genotoxicity of PCH is best evaluated in intact animal models. Our results further support the concept that multiple biomarkers of genotoxicity, especially hematopoietic cell genotoxicity, can be readily combined into one study provided that adequate attention is given to manifestation times. Environ. Mol. Mutagen. 60:505-512, 2019. © 2018 Her Majesty the Queen in Right of Canada.
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Affiliation(s)
- Clotilde Maurice
- Environmental Health Science and Research BureauHealth CanadaOttawaOntarioCanada
| | | | - Carole L. Yauk
- Environmental Health Science and Research BureauHealth CanadaOttawaOntarioCanada
| | - Francesco Marchetti
- Environmental Health Science and Research BureauHealth CanadaOttawaOntarioCanada
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Kirkland D, Uno Y, Luijten M, Beevers C, van Benthem J, Burlinson B, Dertinger S, Douglas GR, Hamada S, Horibata K, Lovell DP, Manjanatha M, Martus HJ, Mei N, Morita T, Ohyama W, Williams A. In vivo genotoxicity testing strategies: Report from the 7th International workshop on genotoxicity testing (IWGT). Mutat Res Genet Toxicol Environ Mutagen 2019; 847:403035. [PMID: 31699340 DOI: 10.1016/j.mrgentox.2019.03.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 03/13/2019] [Accepted: 03/23/2019] [Indexed: 12/14/2022]
Abstract
The working group reached complete or majority agreement on many issues. Results from TGR and in vivo comet assays for 91 chemicals showed they have similar ability to detect in vivo genotoxicity per se with bacterial mutagens and Ames-positive carcinogens. TGR and comet assay results were not significantly different when compared with IARC Group 1, 2 A, and unclassified carcinogens. There were significantly more comet assay positive responses for Group 2B chemicals, and for IARC classified and unclassified carcinogens combined, which may be expected since mutation is a sub-set of genotoxicity. A liver comet assay combined with the bone marrow/blood micronucleus (MNviv) test would detect in vivo genotoxins that do not exhibit tissue-specific or site-of-contact effects, and is appropriate for routine in vivo genotoxicity testing. Generally for orally administered substances, a comet assay at only one site-of-contact GI tract tissue (stomach or duodenum/jejunum) is required. In MNviv tests, evidence of target tissue exposure can be obtained in a number of different ways, as recommended by ICH S2(R1) and EFSA (Hardy et al., 2017). Except for special cases the i.p. route is inappropriate for in vivo testing; for risk evaluations more weight should be given to data from a physiologically relevant administration route. The liver MN test is sufficiently validated for the development of an OECD guideline. However, the impact of dosing animals >6 weeks of age needs to be evaluated. The GI tract MN test shows promise but needs more validation for an OECD guideline. The Pig-a assay detects systemically available mutagens and is a valuable follow-up to in vitro positive results. A new freeze-thaw protocol provides more flexibility. Mutant reticulocyte and erythrocyte frequencies should both be determined. Preliminary data are available for the Pig-a assay in male rat germ cells which require validation including germ cell DNA mutation origin.
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Affiliation(s)
- David Kirkland
- Kirkland Consulting, PO Box 79, Tadcaster, LS24 0AS, United Kingdom.
| | - Yoshifumi Uno
- Mitsubishi Tanabe Pharma Corporation, 2-2-50, Kawagishi, Toda, Saitama, 335-8505, Japan
| | - Mirjam Luijten
- National Institute for Public Health and the Environment (RIVM), Centre for Health Protection, Bilthoven, the Netherlands
| | - Carol Beevers
- Exponent International Ltd., The Lenz, Hornbeam Park, Harrogate, HG2 8RE, United Kingdom
| | - Jan van Benthem
- National Institute for Public Health and the Environment (RIVM), Centre for Health Protection, Bilthoven, the Netherlands
| | - Brian Burlinson
- Envigo, Huntingdon, Cambridgeshire, PE28 4HS, United Kingdom
| | | | - George R Douglas
- Environmental Health Science Research Bureau, Health Canada, Ottawa, K1A 0K9, Canada
| | - Shuichi Hamada
- LSI Medience Corporation, 14-1 Sunayama, Kamisu-shi, Ibaraki, 314-0255, Japan
| | - Katsuyoshi Horibata
- National Institute of Health Sciences, 3-25-26 Tonomachi, Kawasaki, Kanagawa, 210-9501, Japan
| | - David P Lovell
- St George's Medical School, University of London, London, SW17 0RE, United Kingdom
| | | | | | - Nan Mei
- US FDA, National Center for Toxicological Research, Jefferson, AR, USA
| | - Takeshi Morita
- National Institute of Health Sciences, 3-25-26 Tonomachi, Kawasaki, Kanagawa, 210-9501, Japan
| | - Wakako Ohyama
- Yakult Honsha Co., Ltd., 5-11, Izumi, Kunitachi-shi, Tokyo, 186-8650, Japan
| | - Andrew Williams
- Environmental Health Science Research Bureau, Health Canada, Ottawa, K1A 0K9, Canada
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Igl BW, Dertinger SD, Dobrovolsky VN, Raschke M, Sutter A, Vonk R. A statistical approach for analyzing data from the in vivo Pig-a gene mutation assay. Mutat Res Genet Toxicol Environ Mutagen 2018; 831:33-44. [PMID: 29875075 DOI: 10.1016/j.mrgentox.2018.05.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Revised: 03/29/2018] [Accepted: 05/04/2018] [Indexed: 10/17/2022]
Abstract
The in vivo Pig-a gene mutation assay serves to evaluate the genotoxic potential of chemicals. In the rat blood-based assay, the lack of CD59 on the surface of erythrocytes is quantified via fluorophore-labeled antibodies in conjunction with flow cytometric analysis to determine the frequency of Pig-a mutant phenotype cells. The assay has achieved regulatory relevance as it is suggested as an in vivo follow-up test for Ames mutagens in the recent ICH M7 [25] step 4 document. However, very little work exists regarding suitable statistical approaches for analyzing Pig-a data. In the current report, we present a statistical strategy based on a two factor model involving 'treatment' and 'time' incl. their interaction and a baseline covariate for log proportions to compare treatment and vehicle data per time point as well as in time. In doing so, multiple contrast tests allow us to discover time-related changes within and between treatment groups in addition to multiple treatment comparisons to a control group per single time point. We compare our proposed strategy with the results of classical Dunnett and Wilcoxon-Mann-Whitney tests using two data sets describing the mode of action of Chlorambucil and Glycidyl methacrylate both analyzed in a 28-day treatment schedule.
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Affiliation(s)
| | | | - Vasily N Dobrovolsky
- National Center for Toxicological Research/U.S. Food and Drug Administration, Jefferson, AR, USA
| | | | | | - Richardus Vonk
- Research and Clinical Sciences Statistics, Bayer AG, Berlin, Germany
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10
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Long AS, Wills JW, Krolak D, Guo M, Dertinger SD, Arlt VM, White PA. Benchmark dose analyses of multiple genetic toxicity endpoints permit robust, cross-tissue comparisons of MutaMouse responses to orally delivered benzo[a]pyrene. Arch Toxicol 2018; 92:967-982. [PMID: 29177888 PMCID: PMC5818629 DOI: 10.1007/s00204-017-2099-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 10/17/2017] [Indexed: 12/14/2022]
Abstract
Genetic damage is a key event in tumorigenesis, and chemically induced genotoxic effects are a human health concern. Although genetic toxicity data have historically been interpreted using a qualitative screen-and-bin approach, there is increasing interest in quantitative analysis of genetic toxicity dose-response data. We demonstrate an emerging use of the benchmark dose (BMD)-approach for empirically ranking cross-tissue sensitivity. Using a model environmental carcinogen, we quantitatively examined responses for four genetic damage endpoints over an extended dose range, and conducted cross-tissue sensitivity rankings using BMD100 values and their 90% confidence intervals (CIs). MutaMouse specimens were orally exposed to 11 doses of benzo[a]pyrene. DNA adduct frequency and lacZ mutant frequency (MF) were measured in up to 8 tissues, and Pig-a MF and micronuclei (MN) were assessed in immature (RETs) and mature red blood cells (RBCs). The cross-tissue BMD pattern for lacZ MF is similar to that observed for DNA adducts, and is consistent with an oral route-of-exposure and differences in tissue-specific metabolism and proliferation. The lacZ MF BMDs were significantly correlated with the tissue-matched adduct BMDs, demonstrating a consistent adduct conversion rate across tissues. The BMD CIs, for both the Pig-a and the MN endpoints, overlapped for RETs and RBCs, suggesting comparable utility of both cell populations for protracted exposures. Examination of endpoint-specific response maxima illustrates the difficulty of comparing BMD values for a fixed benchmark response across endpoints. Overall, the BMD-approach permitted robust comparisons of responses across tissues/endpoints, which is valuable to our mechanistic understanding of how benzo[a]pyrene induces genetic damage.
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Affiliation(s)
- Alexandra S Long
- Mechanistic Studies Division, Environmental Health Science and Research Bureau, Health Canada, 50 Colombine Driveway, Tunney's Pasture, A/L 0803A, Ottawa, ON, K1A 0K9, Canada.
- Department of Biology, University of Ottawa, Ottawa, ON, Canada.
| | - John W Wills
- Mechanistic Studies Division, Environmental Health Science and Research Bureau, Health Canada, 50 Colombine Driveway, Tunney's Pasture, A/L 0803A, Ottawa, ON, K1A 0K9, Canada
- Department of Biology, University of Ottawa, Ottawa, ON, Canada
| | - Dorothy Krolak
- Mechanistic Studies Division, Environmental Health Science and Research Bureau, Health Canada, 50 Colombine Driveway, Tunney's Pasture, A/L 0803A, Ottawa, ON, K1A 0K9, Canada
| | - Matthew Guo
- Mechanistic Studies Division, Environmental Health Science and Research Bureau, Health Canada, 50 Colombine Driveway, Tunney's Pasture, A/L 0803A, Ottawa, ON, K1A 0K9, Canada
| | | | - Volker M Arlt
- Analytical and Environmental Sciences Division, MRC-PHE Centre for Environment and Health, King's College London, London, UK
| | - Paul A White
- Mechanistic Studies Division, Environmental Health Science and Research Bureau, Health Canada, 50 Colombine Driveway, Tunney's Pasture, A/L 0803A, Ottawa, ON, K1A 0K9, Canada
- Department of Biology, University of Ottawa, Ottawa, ON, Canada
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11
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Avlasevich SL, Labash C, Torous DK, Bemis JC, MacGregor JT, Dertinger SD. In vivo pig-a and micronucleus study of the prototypical aneugen vinblastine sulfate. Environ Mol Mutagen 2018; 59:30-37. [PMID: 28833575 PMCID: PMC5773054 DOI: 10.1002/em.22122] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 07/12/2017] [Accepted: 07/15/2017] [Indexed: 05/05/2023]
Abstract
The Pig-a assay is being used in regulatory studies to evaluate the potential of agents to induce somatic cell gene mutations and an OECD test guideline is under development. A working group involved with establishing the guideline recently noted that representative aneugenic agents had not been evaluated, and to help fill this data gap Pig-a mutant phenotype and micronucleated reticulocyte frequencies were measured in an integrated study design to assess the mutagenic and cytogenetic damage responses to vinblastine sulfate exposure. Male Sprague Dawley rats were treated for twenty-eight consecutive days with vinblastine dose levels from 0.0156 to 0.125 mg/kg/day. Micronucleated reticulocyte frequencies in peripheral blood were determined at Days 4 and 29, and mutant cell frequencies were determined at Days -4, 15, 29, and 46. Vinblastine affected reticulocyte frequencies, with reductions noted during the treatment phase and increases observed following cessation of treatment. Micronucleated reticulocyte frequencies were significantly elevated at Day 4 in the high dose group. Although a statistically significant increase in mutant reticulocyte frequencies were found for one dose group at a single time point (Day 46), it was not deemed biologically relevant because there was no analogous finding in mutant RBCs, it occurred at the lowest dose tested, and only 1 rat exceeded an upper bound tolerance interval established with historical negative control rats. Therefore, whereas micronucleus induction reflects vinblastine's well-established aneugenic effect on hematopoietic cells, the lack of a Pig-a response indicates that this tubulin-binding agent does not cause appreciable mutagenicity in this same cell type. Environ. Mol. Mutagen. 59:30-37, 2018. © 2017 Wiley Periodicals, Inc.
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12
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Olsen AK, Dertinger SD, Krüger CT, Eide DM, Instanes C, Brunborg G, Hartwig A, Graupner A. The Pig-a Gene Mutation Assay in Mice and Human Cells: A Review. Basic Clin Pharmacol Toxicol 2017; 121 Suppl 3:78-92. [PMID: 28481423 DOI: 10.1111/bcpt.12806] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 05/01/2017] [Indexed: 01/08/2023]
Abstract
This MiniReview describes the principle of mutation assays based on the endogenous Pig-a gene and summarizes results for two species of toxicological interest, mice and human beings. The work summarized here largely avoids rat-based studies, as are summarized elsewhere. The Pig-a gene mutation assay has emerged as a valuable tool for quantifying in vivo and in vitro mutational events. The Pig-a locus is located at the X-chromosome, giving the advantage that one inactivated allele can give rise to a mutated phenotype, detectable by multicolour flow cytometry. For in vivo studies, only minute blood volumes are required, making it easily incorporated into ongoing studies or experiments with limited biological materials. Low blood volumes also allow individuals to serve as their own controls, providing temporal information of the mutagenic process, and/or outcome of intervention. These characteristics make it a promising exposure marker. To date, the Pig-a gene mutation assay has been most commonly performed in rats, while reports regarding its usefulness in other species are accumulating. Besides its applicability to in vivo studies, it holds promise for genotoxicity testing using cultured cells, as shown in recent studies. In addition to safety assessment roles, it is becoming a valuable tool in basic research to identify mutagenic effects of different interventions or to understand implications of various gene defects by investigating modified mouse models or cell systems. Human blood-based assays are also being developed that may be able to identify genotoxic environmental exposures, treatment- and lifestyle-related factors or endogenous host factors that contribute to mutagenesis.
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Affiliation(s)
- Ann-Karin Olsen
- Department of Molecular Biology, The Norwegian Institute of Public Health, Oslo, Norway.,Centre for Environmental Radioactivity (CERAD CoE), Norway
| | | | - Christopher T Krüger
- Food Chemistry and Toxicology, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
| | - Dag M Eide
- Centre for Environmental Radioactivity (CERAD CoE), Norway.,Department of Toxicology and Risk, The Norwegian Institute of Public Health, Oslo, Norway
| | - Christine Instanes
- Department of Molecular Biology, The Norwegian Institute of Public Health, Oslo, Norway.,Centre for Environmental Radioactivity (CERAD CoE), Norway
| | - Gunnar Brunborg
- Department of Molecular Biology, The Norwegian Institute of Public Health, Oslo, Norway.,Centre for Environmental Radioactivity (CERAD CoE), Norway
| | - Andrea Hartwig
- Food Chemistry and Toxicology, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
| | - Anne Graupner
- Department of Molecular Biology, The Norwegian Institute of Public Health, Oslo, Norway.,Centre for Environmental Radioactivity (CERAD CoE), Norway
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Hemingway R, Fowkes A, Williams RV. Carbamates and ICH M7 classification: Making use of expert knowledge. Regul Toxicol Pharmacol 2017; 86:392-401. [DOI: 10.1016/j.yrtph.2017.03.025] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 03/27/2017] [Accepted: 03/30/2017] [Indexed: 02/01/2023]
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14
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Castel P, Carcopino X, Robert S, Bonetto R, Cowen D, Orsiere T. [The PIG-A gene as a new biomarker of mutagenesis: proof of concept and technical specifications]. Med Sci (Paris) 2017; 33:432-439. [PMID: 28497740 DOI: 10.1051/medsci/20173304014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Gene mutations are not directly detected by current genotoxicity assays and most of them need a cell culture step. The whole blood PIG-A assay consists in the detection of the mutation frequency within the PIG-A sentinel gene by identification of glycosyl-phosphatidyl-inositol (GPI-) deficient cells. PIG-A mutated/GPI-deficient cells can be detected by flow cytometry as they no longer express surface fluorescence for GPI-linked markers. The last researches have focused on cell enrichment techniques leading to increased throughput and sensitivity. The results of this new and promising biomarker of mutagenesis, performed in humans or rodents, are now available within 2 hours after blood collection.
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Affiliation(s)
- Pierre Castel
- Institut Méditerranéen de Biodiversité et d'Écologie (IMBE), équipe Biogénotoxicologie, Santé Humaine et Environnement, Aix-Marseille Université (AMU), CNRS, IRD, Avignon Université, Faculté de Médecine de Marseille, 27, boulevard Jean Moulin, 13005 Marseille, France
| | - Xavier Carcopino
- Institut Méditerranéen de Biodiversité et d'Écologie (IMBE), équipe Biogénotoxicologie, Santé Humaine et Environnement, Aix-Marseille Université (AMU), CNRS, IRD, Avignon Université, Faculté de Médecine de Marseille, 27, boulevard Jean Moulin, 13005 Marseille, France - Département d'obstétrique et de gynécologie, Hôpital Nord, APHM, Aix-Marseille Université (AMU), Marseille, France
| | - Stéphane Robert
- Vascular Research Center of Marseille, Aix-Marseille Université (AMU), UMR Inserm 1076, Faculté de Pharmacie, Marseille, France
| | - Rémi Bonetto
- Département de Radiothérapie, Hôpital Nord, APHM, Aix-Marseille Université (AMU), Marseille, France
| | - Didier Cowen
- Département de Radiothérapie, Hôpital Nord, APHM, Aix-Marseille Université (AMU), Marseille, France
| | - Thierry Orsiere
- Institut Méditerranéen de Biodiversité et d'Écologie (IMBE), équipe Biogénotoxicologie, Santé Humaine et Environnement, Aix-Marseille Université (AMU), CNRS, IRD, Avignon Université, Faculté de Médecine de Marseille, 27, boulevard Jean Moulin, 13005 Marseille, France
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15
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Wang L, Xu W, Ma L, Zhang S, Zhang K, Ye P, Xing G, Zhang X, Cao Y, Xi J, Gu J, Luan Y. Detoxification of benzo[a]pyrene primarily depends on cytochrome P450, while bioactivation involves additional oxidoreductases including 5-lipoxygenase, cyclooxygenase, and aldo-keto reductase in the liver. J Biochem Mol Toxicol 2017; 31. [PMID: 28111842 DOI: 10.1002/jbt.21902] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Revised: 12/26/2016] [Accepted: 01/03/2017] [Indexed: 02/02/2023]
Abstract
Cytochrome P450s are involved in detoxification and activation of benzo[a]pyrene (BaP) with unclear balance and unknown contribution of other oxidoreductases. Here, we investigated the BaP and BaP-induced mutagenicity in hepatic and extra-hepatic tissues using hepatic P450 reductase null (HRN) gpt mice. After 2-week treatment (50 mg/kg, i.p. 4 days), BaP in the liver and lung of HRN-gpt mice were increased. BaP promoted gpt mutant frequency (MF) in HRN-gpt mice liver. MF of gpt in the lung and Pig-a in hematopoietic cells induced by BaP in HRN-gpt mice were increased than in gpt mice. BaP-7,8-diol-9,10-epoxide (BPDE)-DNA adducts in vitro was analyzed for enzymes detection in BaP bioactivation. Specific inhibitors of 5-lipoxygenase, cyclooxygenase-1&2, and aldo-keto reductase resulted in more than 80% inhibition rate in the DNA adduct formation, further confirmed by Macaca fascicularis hepatic S9 system. Our results suggested the detoxification of BaP primarily depends on cytochrome P450, while the bioactivation involves additional oxidoreductases.
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Affiliation(s)
- Liupeng Wang
- Hongqiao International Institute of Medicine, Shanghai Tong Ren Hospital and Faculty of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China
| | - Wenwei Xu
- Tong Ren Hospital Affiliated To Shanghai Jiao Tong University School of Medicine, Shanghai, 200336, People's Republic of China
| | - Leilei Ma
- Hongqiao International Institute of Medicine, Shanghai Tong Ren Hospital and Faculty of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China
| | - Suxing Zhang
- KG Pharma Limited, Foshan, 528000, People's Republic of China
| | - Kezhi Zhang
- KG Pharma Limited, Foshan, 528000, People's Republic of China
| | - Peizhen Ye
- KG Pharma Limited, Foshan, 528000, People's Republic of China
| | - Guozhen Xing
- Jiangsu Tripod Preclinical Research Laboratories, Pukou Economic Development Zone, Nanjing, People's Republic of China
| | - Xuefeng Zhang
- Jiangsu Tripod Preclinical Research Laboratories, Pukou Economic Development Zone, Nanjing, People's Republic of China
| | - Yiyi Cao
- Hongqiao International Institute of Medicine, Shanghai Tong Ren Hospital and Faculty of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China
| | - Jing Xi
- Hongqiao International Institute of Medicine, Shanghai Tong Ren Hospital and Faculty of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China
| | - Jun Gu
- Wadsworth Center, New York State Department of Health, Albany, NY, 12201-0509, USA
| | - Yang Luan
- Hongqiao International Institute of Medicine, Shanghai Tong Ren Hospital and Faculty of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China
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16
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Raschke M, Igl BW, Kenny J, Collins J, Dertinger SD, Labash C, Bhalli JA, Tebbe CCM, McNeil KM, Sutter A. In Vivo Pig-a gene mutation assay: Guidance for 3Rs-friendly implementation. Environ Mol Mutagen 2016; 57:678-686. [PMID: 27770464 DOI: 10.1002/em.22060] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Accepted: 09/15/2016] [Indexed: 06/06/2023]
Abstract
The rodent Pig-a assay is an in vivo method for the detection of gene mutation, where lack of glycosylphosphatidylinositol-anchored proteins on the surface of circulating red blood cells (RBCs) serves as a reporter for Pig-a gene mutation. In the case of rats, the frequency of mutant phenotype RBCs is measured via fluorescent anti-CD59 antibodies and flow cytometry. The Pig-a assay meets the growing expectations for novel approaches in animal experimentation not only focusing on the scientific value of the assay but also on animal welfare aspects (3Rs principles), for example, amenable to integration into pivotal rodent 28-day general toxicology studies. However, as recommended in the Organisation for Economic Co-operation and Development Test Guidelines for genotoxicity testing, laboratories are expected to demonstrate their proficiency. While this has historically involved the extensive use of animals, here we describe an alternative approach based on a series of blood dilutions covering a range of mutant frequencies. The experiments described herein utilized either non-fluorescent anti-CD59 antibodies to provide elevated numbers of mutant-like cells, or a low volume blood sample from a single N-ethyl-N-nitrosourea treated animal. Results from these so-called reconstruction experiments from four independent laboratories showed good overall precision (correlation coefficients: 0.9979-0.9999) and accuracy (estimated slope: 0.71-1.09) of mutant cell scoring, which was further confirmed by Bland-Altman analysis. These data strongly support the use of reconstruction experiments for training purposes and demonstrating laboratory proficiency with very few animals, an ideal situation given the typically conflicting goals of demonstrating laboratory proficiency and reducing the use of animals. Environ. Mol. Mutagen. 57:678-686, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Marian Raschke
- Bayer Pharma AG, Muellerstrasse 178, Berlin, 13353, Germany
| | - Bernd-W Igl
- Bayer Pharma AG, Muellerstrasse 178, Berlin, 13353, Germany
| | - Julia Kenny
- GlaxoSmithKline, Park Road, Ware, Hertfordshire, SG12 0DP, United Kingdom
| | - Joanne Collins
- GlaxoSmithKline, Park Road, Ware, Hertfordshire, SG12 0DP, United Kingdom
| | | | - Carson Labash
- Litron Laboratories, 3500 Winton Place, Rochester, New York, 14623
| | - Javed A Bhalli
- Covance Laboratories Inc, 671 S. Meridian Rd, Greenfield, Indiana, 46140
| | - Cameron C M Tebbe
- Covance Laboratories Inc, 671 S. Meridian Rd, Greenfield, Indiana, 46140
| | - Kylie M McNeil
- Covance Laboratories Inc, 671 S. Meridian Rd, Greenfield, Indiana, 46140
| | - Andreas Sutter
- Bayer Pharma AG, Muellerstrasse 178, Berlin, 13353, Germany
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17
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Wickliffe JK, Dertinger SD, Torous DK, Avlasevich SL, Simon-Friedt BR, Wilson MJ. Diet-induced obesity increases the frequency of Pig-a mutant erythrocytes in male C57BL/6J mice. Environ Mol Mutagen 2016; 57:668-677. [PMID: 27739633 PMCID: PMC5118159 DOI: 10.1002/em.22058] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 09/12/2016] [Accepted: 09/14/2016] [Indexed: 05/10/2023]
Abstract
Obesity increases the risk of a number of chronic diseases in humans including several cancers. Biological mechanisms responsible for such increased risks are not well understood at present. Increases in systemic inflammation and oxidative stress, endogenous production of mutagenic metabolites, altered signaling in proliferative pathways, and increased sensitivity to exogenous mutagens and carcinogens are some of the potential contributing factors. We hypothesize that obesity creates an endogenously mutagenic environment in addition to increasing the sensitivity to environmental mutagens. To test this hypothesis, we examined two in vivo genotoxicity endpoints. Pig-a mutant frequencies and micronucleus frequencies were determined in blood cells in two independent experiments in 30-week old male mice reared on either a high-fat diet (60% calories from fat) that exhibit an obese phenotype or a normal-fat diet (10% calories from fat) that do not exhibit an obese phenotype. Mice were assayed again at 52 weeks of age in one of the experiments. N-ethyl-N-nitrosourea (ENU) was used as a positive mutation control in one experiment. ENU induced a robust Pig-a mutant and micronucleus response in both phenotypes. Obese, otherwise untreated mice, did not differ from non-obese mice with respect to Pig-a mutant frequencies in reticulocytes or micronucleus frequencies. However, such mice, had significantly higher and sustained Pig-a mutant frequencies (increased 2.5-3.7-fold, p < 0.02) in erythrocytes as compared to non-obese mice (based on measurements collected at 30 weeks or 30 and 52 weeks of age). This suggests that obesity, in the absence of exposure to an exogenous mutagen, is itself mutagenic. Environ. Mol. Mutagen. 57:668-677, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Jeffrey K. Wickliffe
- Department of Global Environmental Health Sciences, School of Public Health and Tropical Medicine, Tulane University, New Orleans, LA 70112 USA
| | | | | | | | - Bridget R. Simon-Friedt
- Department of Global Environmental Health Sciences, School of Public Health and Tropical Medicine, Tulane University, New Orleans, LA 70112 USA
| | - Mark J. Wilson
- Department of Global Environmental Health Sciences, School of Public Health and Tropical Medicine, Tulane University, New Orleans, LA 70112 USA
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18
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Yoshida I, Matsumoto A, Sakai Y, Harada Y, Hashizume T. Pyrene did not induce gene mutation in red blood cell Pig-a assay and PIGRET assay in rats. Mutat Res Genet Toxicol Environ Mutagen 2016; 811:49-53. [PMID: 27931814 DOI: 10.1016/j.mrgentox.2016.04.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 04/19/2016] [Indexed: 11/23/2022]
Abstract
A new in vivo gene mutation assay has been developed based on the phosphatidylinositol glycan anchor biosynthesis, Class A gene (Pig-a in rodents) as an endogenous reporter. Although a large number of chemicals have been evaluated in the rat Pig-a assay in 28-day repeat dose regimens, there was limited reporting of rat Pig-a assay after a single dose. A collaborative study by the Mammalian Mutagenicity Study group, which is a subgroup of the Japanese Environmental Mutagen Society, was conducted to verify the usefulness of the rat Pig-a assay after a single dose as a short-term genotoxicity test. As a part of this collaborative study, the in vivo mutagenicity of a single dose of pyrene (Pyr) was investigated in the red blood cell (RBC Pig-a assay) and in reticulocytes (PIGRET) of rats. Eight-week old male rats were orally dosed with Pyr at 500, 1000, and 2000 mg/kg or ethylnitrosourea (ENU) at 10 and 40 mg/kg as a positive control. The animals in each group were examined for Pig-a mutant frequencies (MF) except for animals in the 2000mg/kg group because of mortality or severe toxicity. The Pig-a MF in RBCs and reticulocytes, as CD59 negative cells, were evaluated once a week for 4 weeks after the dosing. With a single exposure to ENU, the Pig-a MF in both RBCs and reticulocytes increased in a time- and dose-dependent manner. In contrast, no statistically significant effect was observed in rats dosed with Pyr at 500 and 1000 mg/kg. Therefore, Pyr was concluded to be negative in the RBC Pig-a assay and the PIGRET assay after a single oral administration in rats. The result was consistent with previously reported Pig-a assays with repeat dose regimens.
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Hobbs CA, Davis J, Shepard K, Chepelev N, Friedman M, Marroni D, Recio L. Differential genotoxicity of acrylamide in the micronucleus andPig-a gene mutation assays in F344 rats and B6C3F1 mice. Mutagenesis 2016; 31:617-626. [DOI: 10.1093/mutage/gew028] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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20
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Dalrymple A, Ordoñez P, Thorne D, Walker D, Camacho OM, Büttner A, Dillon D, Meredith C. Cigarette smoke induced genotoxicity and respiratory tract pathology: evidence to support reduced exposure time and animal numbers in tobacco product testing. Inhal Toxicol 2016; 28:324-38. [PMID: 27160659 PMCID: PMC4898166 DOI: 10.3109/08958378.2016.1170911] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 03/03/2016] [Accepted: 03/21/2016] [Indexed: 11/13/2022]
Abstract
Many laboratories are working to develop in vitro models that will replace in vivo tests, but occasionally there remains a regulatory expectation of some in vivo testing. Historically, cigarettes have been tested in vivo for 90 days. Recently, methods to reduce and refine animal use have been explored. This study investigated the potential of reducing animal cigarette smoke (CS) exposure to 3 or 6 weeks, and the feasibility of separate lung lobes for histopathology or the Comet assay. Rats were exposed to sham air or CS (1 or 2 h) for 3 or 6 weeks. Respiratory tissues were processed for histopathological evaluation, and Alveolar type II cells (AEC II) isolated for the Comet assay. Blood was collected for Pig-a and micronucleus quantification. Histopathological analyses demonstrated exposure effects, which were generally dependent on CS dose (1 or 2 h, 5 days/week). Comet analysis identified that DNA damage increased in AEC II following 3 or 6 weeks CS exposure, and the level at 6 weeks was higher than 3 weeks. Pig-a mutation or micronucleus levels were not increased. In conclusion, this study showed that 3 weeks of CS exposure was sufficient to observe respiratory tract pathology and DNA damage in isolated AEC II. Differences between the 3 and 6 week data imply that DNA damage in the lung is cumulative. Reducing exposure time, plus analyzing separate lung lobes for DNA damage or histopathology, supports a strategy to reduce and refine animal use in tobacco product testing and is aligned to the 3Rs (replacement, reduction and refinement).
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Affiliation(s)
| | - Patricia Ordoñez
- Vivotecnia Research S.L., Parque Científico de Madrid,
Tres Cantos,
Madrid,
Spain
| | - David Thorne
- British American Tobacco, R&D,
Southampton,
Hampshire,
UK
| | - David Walker
- British American Tobacco, R&D,
Southampton,
Hampshire,
UK
| | | | | | - Debbie Dillon
- British American Tobacco, R&D,
Southampton,
Hampshire,
UK
| | - Clive Meredith
- British American Tobacco, R&D,
Southampton,
Hampshire,
UK
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