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Ohyama W, Fujiishi Y, Okada E, Narumi K, Hayashi M. Micronucleus test using formalin-fixed rat glandular stomach and colon. Genes Environ 2023; 45:4. [PMID: 36639788 PMCID: PMC9840323 DOI: 10.1186/s41021-023-00259-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Accepted: 01/05/2023] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND Genotoxicity in tissues other than hematopoietic tissues, such as the liver and gastrointestinal (GI) tract, is an important focus in the risk assessment of chemicals in humans. We previously developed a rat micronucleus test for the GI tract, which is the first contact tissue where chemicals are introduced into the body through oral exposure. Target cells were obtained from fresh tissue samples by ethylenediaminetetraacetic acid disodium salt (EDTA) treatment. As an improvement to this method, we have used formalin-fixed tissues instead of fresh tissues; this approach can be used for tissues that are sampled from other toxicological tests and that are archived for several years. This new method can be used for examining micronucleus induction retrospectively when needed. In the present study, we compared the performance of the EDTA method and the new method with formalin-fixed tissues (formalin-fixation method). RESULTS Histological examination showed that both the EDTA and formalin-fixation methods could be used for collecting cells located in or above the proliferative zone of the GI tract tissues of rats. In addition, the collected cells were similar in shape. We conducted micronucleus tests with rat GI tract tissues by the two methods using model chemicals, which were used as positive control chemicals (a combination of diethylnitrosamine, 1,2-dimethylhydrazine dihydrochloride, and potassium bromate). The two methods showed similar results. We additionally evaluated the aging effect of tissues stored in formalin fixative. The results showed that 1 year of storage did not affect the frequency of micronucleated cells. CONCLUSION The equivalence of the EDTA and formalin-fixation methods was confirmed, and micronucleus analysis was possible up to at least 1 year after formalin fixation of the GI tract, indicating that the formalin-fixation method is valuable for the rat GI tract micronucleus test.
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Affiliation(s)
- Wakako Ohyama
- grid.433815.80000 0004 0642 4437Yakult Central Institute, Yakult Honsha Co., Ltd., 5-11 Izumi, Kunitachi-shi, Tokyo, 186-8650 Japan
| | - Yohei Fujiishi
- grid.433815.80000 0004 0642 4437Yakult Central Institute, Yakult Honsha Co., Ltd., 5-11 Izumi, Kunitachi-shi, Tokyo, 186-8650 Japan
| | - Emiko Okada
- grid.433815.80000 0004 0642 4437Yakult Central Institute, Yakult Honsha Co., Ltd., 5-11 Izumi, Kunitachi-shi, Tokyo, 186-8650 Japan
| | - Kazunori Narumi
- grid.433815.80000 0004 0642 4437Yakult Central Institute, Yakult Honsha Co., Ltd., 5-11 Izumi, Kunitachi-shi, Tokyo, 186-8650 Japan
| | - Makoto Hayashi
- makoto international consulting, 4-23-3-1, Kamiimaizumi, Ebina-shi, Kanagawa 243-0431 Japan
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Evaluation of a 4-day repeated-dose micronucleus test in rat glandular stomach and colon using aneugens and non-genotoxic non-carcinogens. Genes Environ 2022; 44:12. [PMID: 35410395 PMCID: PMC9004010 DOI: 10.1186/s41021-022-00241-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 03/27/2022] [Indexed: 12/03/2022] Open
Abstract
Background We previously developed a rodent gastrointestinal (GI) tract micronucleus (MN) test using the glandular stomach and/or colon, and evaluated this test method using several genotoxic carcinogens (clastogens) and genotoxic non-carcinogens; we demonstrated that this test method could detect genotoxic stomach and/or colon carcinogens with target organ specificity. In the present study, we further evaluated the sensitivity and specificity of the MN test for the rat glandular stomach and colon using three aneugens (colchicine, vinblastine sulfate, and docetaxel hydrate) and two non-genotoxic non-carcinogens (sodium chloride and sucrose). Results Male Crl:CD (SD) rats were administered test compounds through clinical administration route (orally or intravenously) for four consecutive days and then examined for the micronucleated cell frequencies in the glandular stomach and colon. We observed that all three aneugens significantly and dose-dependently increased the micronucleated cell frequencies in the stomach and colon. In contrast, neither of the two non-genotoxic non-carcinogens increased the micronucleated cell frequency in these tissues. Notably, an increase in cell proliferation was observed in the glandular stomach of rats administered a stomach toxicant, sodium chloride, but this increase did not affect the induction of micronuclei in the gastric cells. Conclusions In the present study, it was demonstrated that the glandular stomach and colon MN tests could detect aneugens as positive and could adequately evaluate non-genotoxic non-carcinogens as negative, including a chemical that enhances cell proliferation. These results provide important evidence supporting good performance of the rat glandular stomach and colon MN tests with a 4-day treatment regimen.
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Hori H, Shimoyoshi S, Tanaka Y, Fujii W, Kitagawa Y, Hayashi M. Target-specific micronucleus induction by colon carcinogens: 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine and 1,2-dimethylhydrazine. Regul Toxicol Pharmacol 2020; 112:104578. [PMID: 31935482 DOI: 10.1016/j.yrtph.2020.104578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 12/02/2019] [Accepted: 01/10/2020] [Indexed: 11/30/2022]
Abstract
Genotoxicity occurring at the target organs of carcinogenesis is important for understanding the mechanisms of chemical carcinogenicity and also for setting of threshold estimation. In vivo gene mutations have been evaluated by transgenic animal models in which any organ can be targeted; however, the methodologies that have been applied to assess chromosomal aberrations including micronucleus induction, are organ restricted, (often to bone marrow hematopoietic cells, as a common example). For food and food-related chemicals, the digestive tract is the important target organ as it is the organ of first contact. In the present study, we used 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) and 1,2-dimethylhydrazine (DMH) as model chemicals of carcinogens primarily targeting the colon. We evaluated the applicability of colon cells and hepatocytes, together with bone marrow cells, in the micronucleus assay. Both model chemicals induced micronuclei in the colon, which is the target organ of these carcinogens, after short- and long-term treatment(s). The results demonstrate the target specificity of micronucleus induction and the assay using organs other than bone marrow will play an important role in understanding the mechanism of carcinogenicity and predicting new carcinogenic agents.
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Affiliation(s)
- Hisako Hori
- Suntory MONOZUKURI Expert Limited, 8-1-1 Seikadai, Seika-cho, Soraku-gun, Kyoto, 619-0284, Japan.
| | - Satomi Shimoyoshi
- Suntory Wellness Limited, 8-1-1 Seikadai, Seika-cho, Soraku-gun, Kyoto, 619-0284, Japan
| | - Yasuhiro Tanaka
- Suntory MONOZUKURI Expert Limited, 8-1-1 Seikadai, Seika-cho, Soraku-gun, Kyoto, 619-0284, Japan
| | - Wataru Fujii
- Suntory MONOZUKURI Expert Limited, 8-1-1 Seikadai, Seika-cho, Soraku-gun, Kyoto, 619-0284, Japan
| | - Yoshinori Kitagawa
- Suntory Wellness Limited, 8-1-1 Seikadai, Seika-cho, Soraku-gun, Kyoto, 619-0284, Japan
| | - Makoto Hayashi
- Makoto International Consulting, 23-3-1, 4-chome, Kami-imaizumi, Ebina, 243-0431, Japan
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Evaluation of a 28-day repeated-dose micronucleus test in rat glandular stomach, colon, and liver using gastrointestinal tract-targeted genotoxic-carcinogens and non-carcinogens. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2019; 844:62-68. [DOI: 10.1016/j.mrgentox.2019.05.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 05/17/2019] [Accepted: 05/17/2019] [Indexed: 11/19/2022]
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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). MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 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] [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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Kishino Y, Hasegawa T, Arakawa S, Shibaya Y, Yamoto T, Mori K. Effect of the metabolic capacity in rat liver S9 on the positive results of in vitro micronucleus tests. J Toxicol Sci 2019; 44:145-153. [PMID: 30842367 DOI: 10.2131/jts.44.145] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
A high incidence of positive results is obtained with in vitro genotoxicity tests, which do not correlate with the in vivo negative results in many cases. To address this issue, the metabolic profile of rat liver 9000 × g supernatant fraction (S9) pretreated with phenobarbital (PB) and 5,6-benzoflavone (BNF) was characterized. Furthermore, the in vitro micronucleus tests of 10 compounds were performed with PB-BNF-induced rat S9. PB-BNF increased cytochrome P450 (CYP) activity and CYP1A1, CYP1A2, CYP2B1/2, CYP2C6, CYP3A1, and CYP3A2 expression in rat S9, whereas it decreased CYP2C11 and CYP2E1 expression. PB-BNF-induced S9 enhanced the micronucleus induction (MI) of benzo[a]pyrene (BaP), cyclophosphamide (CPA), and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine hydrochloride (PhIP), which are metabolized by CYP1A1, CYP2C6, and CYP1A2, respectively. In contrast, coumarin and chlorpheniramine showed MI with PB-BNF-induced S9 despite the fact that they show negative results in the in vivo studies. Furthermore, diclofenac, piroxicam, lansoprazole, and caffeine showed MI regardless of the enzyme induction by PB-BNF, whereas phenacetin did not show MI. These results indicate that PB-BNF-induced rat S9 is effective in detecting the genotoxic potential of promutagens, such as BaP, CPA, and PhIP, but not of coumarin and chlorpheniramine, probably due to the differences in the in vitro and in vivo metabolic profile and its exposure levels of the drugs.
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Affiliation(s)
- Yuki Kishino
- Medicinal Safety Research Laboratories, Daiichi Sankyo Co., Ltd
| | - Tomoko Hasegawa
- Medicinal Safety Research Laboratories, Daiichi Sankyo Co., Ltd
| | - Shingo Arakawa
- Medicinal Safety Research Laboratories, Daiichi Sankyo Co., Ltd
| | - Yukari Shibaya
- Medicinal Safety Research Laboratories, Daiichi Sankyo Co., Ltd
| | - Takashi Yamoto
- Medicinal Safety Research Laboratories, Daiichi Sankyo Co., Ltd
| | - Kazuhiko Mori
- Medicinal Safety Research Laboratories, Daiichi Sankyo Co., Ltd
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Thompson CM, Suh M, Proctor DM, Haws LC, Harris MA. Ten factors for considering the mode of action of Cr(VI)-induced gastrointestinal tumors in rodents. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2017; 823:45-57. [DOI: 10.1016/j.mrgentox.2017.08.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Revised: 08/26/2017] [Accepted: 08/28/2017] [Indexed: 12/28/2022]
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Pak B, Han S, Lee J, Chung YS. Evaluation of in vivo Genotoxicity of Plant Flavonoids, Quercetin and Isoquercetin. ACTA ACUST UNITED AC 2016. [DOI: 10.13103/jfhs.2016.31.5.356] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Morita T, Hamada S, Masumura K, Wakata A, Maniwa J, Takasawa H, Yasunaga K, Hashizume T, Honma M. Evaluation of the sensitivity and specificity of in vivo erythrocyte micronucleus and transgenic rodent gene mutation tests to detect rodent carcinogens. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2016; 802:1-29. [DOI: 10.1016/j.mrgentox.2016.03.008] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Revised: 03/14/2016] [Accepted: 03/16/2016] [Indexed: 11/26/2022]
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Uno Y, Morita T, Luijten M, Beevers C, Hamada S, Itoh S, Ohyama W, Takasawa H. Micronucleus test in rodent tissues other than liver or erythrocytes: Report of the IWGT working group. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2015; 783:19-22. [PMID: 25953397 DOI: 10.1016/j.mrgentox.2015.03.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 03/03/2015] [Indexed: 10/23/2022]
Abstract
At the 6th International Workshop on Genotoxicity Testing, the liver micronucleus test (MNT) working group briefly discussed the MNT using tissues other than liver/erythrocytes. Many tissues other than liver/erythrocytes have been studied, primarily for research purposes. They have included the colon and intestinal epithelium, skin, spleen, lung, stomach, bladder, buccal mucosa, vagina, and fetal/neonatal tissues. These tissues were chosen because they were target sites of carcinogens, and/or relevant to a specific route of exposure. Recently, there has been particular focus on the gastrointestinal (GI) tract as it is a contact site associated with high exposure following oral gavage. Furthermore GI tumors are observed with high frequency in human populations. A collaborative study of the rat glandular stomach and colon MNT was conducted in conjunction with a collaborative study of the repeated-dose liver MNT. Based on limited data currently available, the rodent MNT using the glandular stomach and/or colon seems to detect genotoxic carcinogens with GI tract target-organ specificity. The working group concluded that the GI tract MNT would be a promising method to examine clastogenicity or aneugenicity of test chemicals in the stomach and/or colon. Further data will be needed to fully establish the methods, and to identify the sensitivity and specificity of the GI tract MNT.
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Affiliation(s)
| | | | - Mirjam Luijten
- National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands
| | | | - Shuichi Hamada
- LSI Medience (Formerly Mitsubishi Chemical Medience Co.), Ibaraki, Japan
| | | | | | - Hironao Takasawa
- LSI Medience (Formerly Mitsubishi Chemical Medience Co.), Ibaraki, Japan
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Evaluation of the repeated-dose liver and gastrointestinal tract micronucleus assays with 22 chemicals using young adult rats: Summary of the collaborative study by the Collaborative Study Group for the Micronucleus Test (CSGMT)/The Japanese Environmental Mutagen Society (JEMS) – Mammalian Mutagenicity Study Group (MMS). MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2015; 780-781:2-17. [DOI: 10.1016/j.mrgentox.2015.01.001] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Accepted: 01/02/2015] [Indexed: 11/21/2022]
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Takayanagi T, Wako Y, Kawasako K, Hori H, Fujii W, Ohyama W. Repeated dose liver and gastrointestinal tract micronucleus assays using N-methyl-N′-nitro-N-nitrosoguanidine in young adult rats. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2015; 780-781:100-6. [DOI: 10.1016/j.mrgentox.2014.12.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/25/2014] [Accepted: 12/28/2014] [Indexed: 11/29/2022]
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Okada E, Fujiishi Y, Narumi K, Kado S, Wako Y, Kawasako K, Kaneko K, Ohyama W. Evaluation of repeated dose micronucleus assays of the liver and gastrointestinal tract using potassium bromate: A report of the collaborative study by CSGMT/JEMS.MMS. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2015; 780-781:94-9. [DOI: 10.1016/j.mrgentox.2014.03.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Accepted: 03/05/2014] [Indexed: 11/27/2022]
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