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Gi M, Fujioka M, Totsuka Y, Matsumoto M, Masumura K, Kakehashi A, Yamaguchi T, Fukushima S, Wanibuchi H. Quantitative analysis of mutagenicity and carcinogenicity of 2-amino-3-methylimidazo[4,5-f]quinoline in F344 gpt delta transgenic rats. Mutagenesis 2020; 34:279-287. [PMID: 31233596 DOI: 10.1093/mutage/gez015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Accepted: 06/09/2019] [Indexed: 11/13/2022] Open
Abstract
Quantitative analysis of the mutagenicity and carcinogenicity of the low doses of genotoxic carcinogens present in food is of pressing concern. The purpose of the present study was to determine the mutagenicity and carcinogenicity of low doses of the dietary genotoxic carcinogen 2-amino-3-methylimidazo[4,5-f]quinoline (IQ). Male F344 gpt delta transgenic rats were fed diets supplemented with 0, 0.1, 1, 10 or 100 ppm IQ for 4 weeks. The frequencies of gpt transgene mutations in the liver were significantly increased in the 10 and 100 ppm groups. In addition, the mutation spectra was altered in the 1, 10 and 100 ppm groups: frequencies of G:C to T:A transversion were significantly increased in groups administered 1, 10 and 100 ppm IQ in a dose-dependent manner, and the frequencies of G:C to A:T transitions, A:T to T:A transversions and A:T to C:G transversions were significantly increased in the 100 ppm group. Increased frequencies of single base pair deletions and Spi- mutants in the liver, and an increase in glutathione S-transferase placental form (GST-P)-positive foci, a preneoplastic lesion of the liver in rats, was also observed in the 100 ppm group. In contrast, neither mutations nor mutation spectra or GST-P-positive foci were statistically altered by administration of IQ at 0.1 ppm. We estimated the point of departure for the mutagenicity and carcinogenicity of IQ using the no-observed-effect level approach and the Benchmark dose approach to characterise the dose-response relationship of low doses of IQ. Our findings demonstrate the existence of no effect levels of IQ for both in vivo mutagenicity and hepatocarcinogenicity. The findings of the present study will facilitate an understanding of the carcinogenic effects of low doses of IQ and help to determine a margin of exposure that may be useful for practical human risk assessment.
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Affiliation(s)
- Min Gi
- Department of Molecular Pathology, Osaka City University Graduate School of Medicine, Abeno-ku, Osaka, Japan
| | - Masaki Fujioka
- Department of Molecular Pathology, Osaka City University Graduate School of Medicine, Abeno-ku, Osaka, Japan
| | - Yukari Totsuka
- Division of Carcinogenesis and Cancer Prevention, National Cancer Center Research Institute, Chuo-ku, Tokyo, Japan
| | - Michiharu Matsumoto
- Japan Bioassay Research Center, Japan Organization of Occupational Health and Safety, Hadano, Kanagawa, Japan
| | - Kenichi Masumura
- Division of Genetics and Mutagenesis, National Institute of Health Sciences, Kawasaki-ku, Kawasaki, Kanagawa, Japan
| | - Anna Kakehashi
- Department of Molecular Pathology, Osaka City University Graduate School of Medicine, Abeno-ku, Osaka, Japan
| | - Takashi Yamaguchi
- Department of Molecular Pathology, Osaka City University Graduate School of Medicine, Abeno-ku, Osaka, Japan
| | - Shoji Fukushima
- Japan Bioassay Research Center, Japan Organization of Occupational Health and Safety, Hadano, Kanagawa, Japan.,Association for Promotion of Research on Risk Assessment, Nakagawa-ku, Nagoya, Japan
| | - Hideki Wanibuchi
- Department of Molecular Pathology, Osaka City University Graduate School of Medicine, Abeno-ku, Osaka, Japan
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Nohmi T, Matsumoto K. Effects of DNA polymerase kappa and mismatch repair on dose-responses of chromosome aberrations induced by three oxidative genotoxins in human cells. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2020; 61:193-199. [PMID: 31294882 DOI: 10.1002/em.22315] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Revised: 06/25/2019] [Accepted: 06/27/2019] [Indexed: 06/09/2023]
Abstract
Genotoxic carcinogens are regulated under the policy that there is no threshold or safe dose. It has been pointed out, however, that self-defense mechanisms, such as detoxification, DNA repair, and error-free translesion synthesis, may protect chromosome DNA from genotoxic insults, thereby constituting practical threshold. In this study, we examined dose responses of chromosome aberrations induced by three oxidative genotoxins, that is, hydrogen peroxide (H2 O2 ), menadione and paraquat, with or without DNA polymerase kappa (Polκ) activities and mismatch repair capacities in human cells. Polκ is involved in translesion synthesis across DNA damage and mismatch repair is responsible for correction of base-base mismatch in DNA. Polκ activity of the cells was inactivated either by point mutations in the catalytically essential amino acids (catalytically dead or CD) or by deletion of the POLK gene (knockout or KO). In the absence of mismatch repair, frequencies of chromosome aberrations induced by H2 O2 and menadione were not significantly different among CD, KO, and the wild type (WT) cells. In the presence of mismatch repair, however, cytotoxicity and clastogenicity were enhanced and Polκ modulated the sensitivity of the cells. No-observed-genotoxic-effect-levels (NOGELs) for H2 O2 and menadione were CD = KO < WT cells. In contrast, the sensitivities of the cells to paraquat were not significantly affected by the status of mismatch repair or Polκ activity. The results suggest that mismatch repair and Polκ coordinately modulate NOGELs for the clastogenicity of H2 O2 and menadione and also that DNA lesion(s) responsible for paraquat-induced chromosome aberrations are different from those induced by H2 O2 and menadione. Environ. Mol. Mutagen. 61:193-199, 2020. © 2019 Wiley Periodicals, Inc.
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Affiliation(s)
- Takehiko Nohmi
- Biological Safety Research Center, National Institute of Health Sciences, Kawasaki-shi, Kanagawa, Japan
| | - Kyomu Matsumoto
- Toxicology Division, The Institute of Environmental Toxicology, Joso-shi, Ibaraki, Japan
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3
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Fukushima S, Gi M, Fujioka M, Kakehashi A, Wanibuchi H, Matsumoto M. Quantitative Approaches to Assess Key Carcinogenic Events of Genotoxic Carcinogens. Toxicol Res 2018; 34:291-296. [PMID: 30370003 PMCID: PMC6195881 DOI: 10.5487/tr.2018.34.4.291] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 08/20/2018] [Accepted: 08/30/2018] [Indexed: 11/22/2022] Open
Abstract
Chemical carcinogenesis is a multistep process. Genotoxic carcinogens, which are DNA-reactive, induce DNA adduct formation and genetic alterations in target cells, thereby generating mutated cells (initiation). Subsequently, preneoplastic lesions appear through clonal proliferation of the mutated cells and transform into tumors (promotion and progression). Many factors may influence these processes in a dose-dependent manner. Therefore, quantitative analysis plays an important role in studies on the carcinogenic threshold of genotoxic carcinogens. Herein, we present data on the relationship between key carcinogenic events and their deriving point of departure (PoD). Their PoDs were also compared to those of the carcinogenesis pathway. In an experiment, the liver of rats exposed to 2-amino-3,8-dimethylimidazo-(4,5-f)quinoxaline (MeIQx) was examined to determine the formation of MeIQx-DNA adducts, generation of mutations at LacI transgene, and induction of preneoplastic glutathione S-transferase placental form (GST-P)-positive foci and tumors (benign and malignant). The PoDs of the above key events in the carcinogenicity of MeIQx were increased as the carcinogenesis advanced; however, these PoDs were lower than those of tumor induction. Thus, the order of key events during tumor induction in the liver was as follows: formation of DNA adducts << Mutations << GST-positive foci (preneoplasia) << Tumor (adenoma and carcinoma). We also obtained similar data on the genotoxic and carcinogenic PoDs of other hepatocarcinogens, such as 2-amino-3,8-dimethylimidazo(4,5-f)quinoline. These results contribute to elucidating the existence of a genotoxic and carcinogenic threshold.
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Affiliation(s)
- Shoji Fukushima
- Association for Promotion of Research on Risk Assessment, Nakagawa, Nagoya, Japan.,Japan Bioassay Research Center, Hadano, Kanagawa, Japan
| | - Min Gi
- Department of Molecular Pathology, Osaka City University Graduate School of Medicine, Abeno, Osaka, Japan
| | - Masaki Fujioka
- Department of Molecular Pathology, Osaka City University Graduate School of Medicine, Abeno, Osaka, Japan
| | - Anna Kakehashi
- Department of Molecular Pathology, Osaka City University Graduate School of Medicine, Abeno, Osaka, Japan
| | - Hideki Wanibuchi
- Department of Molecular Pathology, Osaka City University Graduate School of Medicine, Abeno, Osaka, Japan
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4
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Gi M, Fujioka M, Kakehashi A, Okuno T, Masumura K, Nohmi T, Matsumoto M, Omori M, Wanibuchi H, Fukushima S. In vivo positive mutagenicity of 1,4-dioxane and quantitative analysis of its mutagenicity and carcinogenicity in rats. Arch Toxicol 2018; 92:3207-3221. [PMID: 30155721 DOI: 10.1007/s00204-018-2282-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Accepted: 08/02/2018] [Indexed: 12/17/2022]
Abstract
1,4-Dioxane is a widely used synthetic industrial chemical and its contamination of drinking water and food is a potential health concern. It induces liver tumors when administered in the drinking water to rats and mice. However, the mode of action (MOA) of the hepatocarcinogenicity of 1,4-dioxane remains unclear. Importantly, it is unknown if 1,4-dioxane is genotoxic, a key consideration for risk assessment. To determine the in vivo mutagenicity of 1,4-dioxane, gpt delta transgenic F344 rats were administered 1,4-dioxane at various doses in the drinking water for 16 weeks. The overall mutation frequency (MF) and A:T- to -G:C transitions and A:T- to -T:A transversions in the gpt transgene were significantly increased by administration of 5000 ppm 1,4-dioxane. A:T- to -T:A transversions were also significantly increased by administration of 1000 ppm 1,4-dioxane. Furthermore, the DNA repair enzyme MGMT was significantly induced at 5000 ppm 1,4-dioxane, implying that extensive genetic damage exceeded the repair capacity of the cells in the liver and consequently led to liver carcinogenesis. No evidence supporting other MOAs, including induction of oxidative stress, cytotoxicity, or nuclear receptor activation, that could contribute to the carcinogenic effects of 1,4-dioxane were found. These findings demonstrate that 1,4-dioxane is a genotoxic hepatocarcinogen and induces hepatocarcinogenesis through a mutagenic MOA in rats. Because our data indicate that 1,4-dioxane is a genotoxic carcinogen, we estimated the point of departure of the mutagenicity and carcinogenicity of 1,4-dioxane using the no-observed effect-level approach and the Benchmark dose approach to characterize its dose-response relationship at low doses.
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Affiliation(s)
- Min Gi
- Department of Molecular Pathology, Osaka City University Graduate School of Medicine, 1-4-3 Asahi-machi, Abeno-ku, Osaka, 545-8585, Japan
| | - Masaki Fujioka
- Department of Molecular Pathology, Osaka City University Graduate School of Medicine, 1-4-3 Asahi-machi, Abeno-ku, Osaka, 545-8585, Japan
| | - Anna Kakehashi
- Department of Molecular Pathology, Osaka City University Graduate School of Medicine, 1-4-3 Asahi-machi, Abeno-ku, Osaka, 545-8585, Japan
| | - Takahiro Okuno
- Department of Molecular Pathology, Osaka City University Graduate School of Medicine, 1-4-3 Asahi-machi, Abeno-ku, Osaka, 545-8585, Japan
| | - Kenichi Masumura
- Division of Genetics and Mutagenesis, National Institute of Health Sciences, 3-25-26 Tonomachi, Kawasaki-ku, Kawasaki-shi, Kanagawa, 210-9501, Japan
| | - Takehiko Nohmi
- Biological Safety Research Center, National Institute of Health Sciences, 3-25-26 Tonomachi, Kawasaki-ku, Kawasaki-shi, Kanagawa, 210-9501, Japan
| | - Michiharu Matsumoto
- Japan Bioassay Research Center, Japan Organization of Occupational Health and Safety, Hadano, Kanagawa, 257-0015, Japan
| | - Masako Omori
- Association for Promotion of Research on Risk Assessment, Nakagawa-ku, Nagoya, 454-0869, Japan
| | - Hideki Wanibuchi
- Department of Molecular Pathology, Osaka City University Graduate School of Medicine, 1-4-3 Asahi-machi, Abeno-ku, Osaka, 545-8585, Japan
| | - Shoji Fukushima
- Japan Bioassay Research Center, Japan Organization of Occupational Health and Safety, Hadano, Kanagawa, 257-0015, Japan.
- Association for Promotion of Research on Risk Assessment, Nakagawa-ku, Nagoya, 454-0869, Japan.
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Suzuki T, Matsumoto K, Honma M, Nohmi T. Impact of DNA polymerase ζ mutations on genotoxic thresholds of oxidative mutagens. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2018; 828:10-14. [PMID: 29555059 DOI: 10.1016/j.mrgentox.2018.02.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2017] [Revised: 01/31/2018] [Accepted: 02/02/2018] [Indexed: 12/11/2022]
Abstract
In regulatory genetic toxicology, it is an axiom that there is no threshold for genotoxicity of chemicals, such that genotoxic chemicals may impose carcinogenic risk on humans even at very low doses. This paradigm is counterintuitive, however, because humans possess a number of self-defense mechanisms that may suppress the genotoxicity at these low doses and therefore manifest a practical threshold. DNA polymerase zeta (Pol ζ) is a specialized Pol that plays an important role in DNA synthesis across DNA damage, thereby modulating cell survival and genotoxicity. In this study, we compared the sensitivity of three types of human cells: D2781N, L2618M, and their wild-type (WT) cells, to the low dose effects of genotoxicity of the oxidizing agents, potassium bromate (KBrO3) and sodium dichromate (Na2Cr2O7). D2781N cells express a variant form of Pol ζ, whose activity is weaker than that of the WT enzyme. L2618M cells express another variant form of Pol ζ, whose fidelity of DNA replication is lower than that of the WT enzyme. D2781N exhibited the highest sensitivity for TK gene mutation and micronucleus (MN) formation and displayed the lowest practical threshold for MN induction by KBrO3. In contrast, L2618M exhibited the lowest practical threshold for sister-chromatid exchange (SCE) induction by both chemicals. These results suggest that Pol ζ mutations have significant impacts on practical thresholds of genotoxicity; the factors affecting the practical threshold can differ depending on the endpoint of genotoxicity. Roles of the variant forms of Pol ζ in genotoxicity by the oxidizing agents are discussed.
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Affiliation(s)
- Tetsuya Suzuki
- Division of Genetics and Mutagenesis, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan
| | - Kyomu Matsumoto
- Toxicology Division, The Institute of Environmental Toxicology, 4321 Uchimoriya, Joso-shi, Ibaraki, 303-0043, Japan
| | - Masamitsu Honma
- Division of Genetics and Mutagenesis, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan
| | - Takehiko Nohmi
- Division of Genetics and Mutagenesis, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan.
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Fukushima S, Kasai T, Umeda Y, Ohnishi M, Sasaki T, Matsumoto M. Carcinogenicity of multi-walled carbon nanotubes: challenging issue on hazard assessment. J Occup Health 2018; 60:10-30. [PMID: 29046510 PMCID: PMC5799097 DOI: 10.1539/joh.17-0102-ra] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Accepted: 09/10/2017] [Indexed: 01/20/2023] Open
Abstract
OBJECTIVES This report reviews the carcinogenicity of multi-walled carbon nanotubes (MWCNTs) in experimental animals, concentrating on MWNT-7, a straight fibrous MWCNT. METHODS MWCNTs were administered to mice and rats by intraperitoneal injection, intrascrotal injection, subcutaneous injection, intratracheal instillation and inhalation. RESULTS Intraperitoneal injection of MWNT-7 induced peritoneal mesothelioma in mice and rats. Intrascrotal injection induced peritoneal mesothelioma in rats. Intratracheal instillation of MWCNT-N (another straight fibrous MWCNT) induced both lung carcinoma and pleural mesothelioma in rats. In the whole body inhalation studies, in mice MWNT-7 promoted methylcholanthrene-initiated lung carcinogenesis. In rats, inhalation of MWNT-7 induced lung carcinoma and lung burdens of MWNT-7 increased with increasing concentration of airborne MWNT-7 and increasing duration of exposure. CONCLUSIONS Straight, fibrous MWCNTs exerted carcinogenicity in experimental animals. Phagocytosis of MWCNT fibers by macrophages was very likely to be a principle factor in MWCNT lung carcinogenesis. Using no-observed-adverse-effect level-based approach, we calculated that the occupational exposure limit (OEL) of MWNT-7 for cancer protection is 0.15 μg/m3 for a human worker. Further studies on the effects of the shape and size of MWCNT fibers and mode of action on the carcinogenicity are required.
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Affiliation(s)
- Shoji Fukushima
- Japan Bioassay Research Center, Japan Organization of Occupational Health and Safety
- Association for Promotion of Research on Risk Assessment
| | - Tatsuya Kasai
- Japan Bioassay Research Center, Japan Organization of Occupational Health and Safety
| | - Yumi Umeda
- Japan Bioassay Research Center, Japan Organization of Occupational Health and Safety
| | - Makoto Ohnishi
- Japan Bioassay Research Center, Japan Organization of Occupational Health and Safety
| | - Toshiaki Sasaki
- Japan Bioassay Research Center, Japan Organization of Occupational Health and Safety
| | - Michiharu Matsumoto
- Japan Bioassay Research Center, Japan Organization of Occupational Health and Safety
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7
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Bose A, Millsap AD, DeLeon A, Rizzo C, Basu AK. Translesion Synthesis of the N(2)-2'-Deoxyguanosine Adduct of the Dietary Mutagen IQ in Human Cells: Error-Free Replication by DNA Polymerase κ and Mutagenic Bypass by DNA Polymerases η, ζ, and Rev1. Chem Res Toxicol 2016; 29:1549-59. [PMID: 27490094 PMCID: PMC5031085 DOI: 10.1021/acs.chemrestox.6b00221] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Indexed: 12/18/2022]
Abstract
Translesion synthesis (TLS) of the N(2)-2'-deoxyguanosine (dG-N(2)-IQ) adduct of the carcinogen 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) was investigated in human embryonic kidney 293T cells by replicating plasmid constructs in which the adduct was individually placed at each guanine (G1, G2, or G3) of the NarI sequence (5'-CG1G2CG3CC-3'). TLS efficiency was 38%, 29%, and 25% for the dG-N(2)-IQ located at G1, G2, and G3, respectively, which suggests that dG-N(2)-IQ is bypassed more efficiently by one or more DNA polymerases at G1 than at either G2 or G3. TLS efficiency was decreased 8-35% in cells with knockdown of pol η, pol κ, pol ι, pol ζ, or Rev1. Up to 75% reduction in TLS occurred when pol η, pol ζ, and Rev1 were simultaneously knocked down, suggesting that these three polymerases play important roles in dG-N(2)-IQ bypass. Mutation frequencies (MFs) of dG-N(2)-IQ at G1, G2, and G3 were 23%, 17%, and 11%, respectively, exhibiting a completely reverse trend of the previously reported MF of the C8-dG adduct of IQ (dG-C8-IQ), which is most mutagenic at G3 ( ( 2015 ) Nucleic Acids Res. 43 , 8340 - 8351 ). The major type of mutation induced by dG-N(2)-IQ was targeted G → T, as was reported for dG-C8-IQ. In each site, knockdown of pol κ resulted in an increase in MF, whereas MF was reduced when pol η, pol ι, pol ζ, or Rev1 was knocked down. The reduction in MF was most pronounced when pol η, pol ζ, and Rev1 were simultaneously knocked down and especially when the adduct was located at G3, where MF was reduced by 90%. We conclude that pol κ predominantly performs error-free TLS of the dG-N(2)-IQ adduct, whereas pols η, pol ζ, and Rev1 cooperatively carry out the error-prone TLS. However, in vitro experiments using yeast pol ζ and κ showed that the former was inefficient in full-length primer extension on dG-N(2)-IQ templates, whereas the latter was efficient in both error-free and error-prone extensions. We believe that the observed differences between the in vitro experiments using purified DNA polymerases, and the cellular results may arise from several factors including the crucial roles played by the accessory proteins in TLS.
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Affiliation(s)
- Arindam Bose
- Department
of Chemistry, University of Connecticut, Storrs, Connecticut 06269, United States
| | - Amy D. Millsap
- Department
of Chemistry, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Arnie DeLeon
- Department
of Chemistry, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Carmelo
J. Rizzo
- Department
of Chemistry, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Ashis K. Basu
- Department
of Chemistry, University of Connecticut, Storrs, Connecticut 06269, United States
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Liu Y, Yin T, Feng Y, Cona MM, Huang G, Liu J, Song S, Jiang Y, Xia Q, Swinnen JV, Bormans G, Himmelreich U, Oyen R, Ni Y. Mammalian models of chemically induced primary malignancies exploitable for imaging-based preclinical theragnostic research. Quant Imaging Med Surg 2015; 5:708-29. [PMID: 26682141 PMCID: PMC4671963 DOI: 10.3978/j.issn.2223-4292.2015.06.01] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Accepted: 06/15/2015] [Indexed: 12/14/2022]
Abstract
Compared with transplanted tumor models or genetically engineered cancer models, chemically induced primary malignancies in experimental animals can mimic the clinical cancer progress from the early stage on. Cancer caused by chemical carcinogens generally develops through three phases namely initiation, promotion and progression. Based on different mechanisms, chemical carcinogens can be divided into genotoxic and non-genotoxic ones, or complete and incomplete ones, usually with an organ-specific property. Chemical carcinogens can be classified upon their origins such as environmental pollutants, cooked meat derived carcinogens, N-nitroso compounds, food additives, antineoplastic agents, naturally occurring substances and synthetic carcinogens, etc. Carcinogen-induced models of primary cancers can be used to evaluate the diagnostic/therapeutic effects of candidate drugs, investigate the biological influential factors, explore preventive measures for carcinogenicity, and better understand molecular mechanisms involved in tumor initiation, promotion and progression. Among commonly adopted cancer models, chemically induced primary malignancies in mammals have several advantages including the easy procedures, fruitful tumor generation and high analogy to clinical human primary cancers. However, in addition to the time-consuming process, the major drawback of chemical carcinogenesis for translational research is the difficulty in noninvasive tumor burden assessment in small animals. Like human cancers, tumors occur unpredictably also among animals in terms of timing, location and the number of lesions. Thanks to the availability of magnetic resonance imaging (MRI) with various advantages such as ionizing-free scanning, superb soft tissue contrast, multi-parametric information, and utility of diverse contrast agents, now a workable solution to this bottleneck problem is to apply MRI for noninvasive detection, diagnosis and therapeutic monitoring on those otherwise uncontrollable animal models with primary cancers. Moreover, it is foreseeable that the combined use of chemically induced primary cancer models and molecular imaging techniques may help to develop new anticancer diagnostics and therapeutics.
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Bose A, Pande P, Jasti VP, Millsap AD, Hawkins EK, Rizzo CJ, Basu AK. DNA polymerases κ and ζ cooperatively perform mutagenic translesion synthesis of the C8-2'-deoxyguanosine adduct of the dietary mutagen IQ in human cells. Nucleic Acids Res 2015. [PMID: 26220181 PMCID: PMC4787813 DOI: 10.1093/nar/gkv750] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The roles of translesion synthesis (TLS) DNA polymerases in bypassing the C8-2'-deoxyguanosine adduct (dG-C8-IQ) formed by 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), a highly mutagenic and carcinogenic heterocyclic amine found in cooked meats, were investigated. Three plasmid vectors containing the dG-C8-IQ adduct at the G1-, G2- or G3-positions of the NarI site (5'-G1G2CG3CC-3') were replicated in HEK293T cells. Fifty percent of the progeny from the G3 construct were mutants, largely G→T, compared to 18% and 24% from the G1 and G2 constructs, respectively. Mutation frequency (MF) of dG-C8-IQ was reduced by 38-67% upon siRNA knockdown of pol κ, whereas it was increased by 10-24% in pol η knockdown cells. When pol κ and pol ζ were simultaneously knocked down, MF of the G1 and G3 constructs was reduced from 18% and 50%, respectively, to <3%, whereas it was reduced from 24% to <1% in the G2 construct. In vitro TLS using yeast pol ζ showed that it can extend G3*:A pair more efficiently than G3*:C pair, but it is inefficient at nucleotide incorporation opposite dG-C8-IQ. We conclude that pol κ and pol ζ cooperatively carry out the majority of the error-prone TLS of dG-C8-IQ, whereas pol η is involved primarily in its error-free bypass.
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Affiliation(s)
- Arindam Bose
- Department of Chemistry, University of Connecticut, Storrs, CT 06269, USA
| | - Paritosh Pande
- Department of Chemistry, University of Connecticut, Storrs, CT 06269, USA
| | - Vijay P Jasti
- Department of Chemistry, University of Connecticut, Storrs, CT 06269, USA
| | - Amy D Millsap
- Department of Chemistry, Vanderbilt University, Nashville, TN 37232, USA
| | - Edward K Hawkins
- Department of Chemistry, Vanderbilt University, Nashville, TN 37232, USA
| | - Carmelo J Rizzo
- Department of Chemistry, Vanderbilt University, Nashville, TN 37232, USA
| | - Ashis K Basu
- Department of Chemistry, University of Connecticut, Storrs, CT 06269, USA
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Fukushima S, Gi M, Kakehashi A, Wanibuchi H, Matsumoto M. Qualitative and quantitative approaches in the dose–response assessment of genotoxic carcinogens. Mutagenesis 2015; 31:341-6. [DOI: 10.1093/mutage/gev049] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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11
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Wei M, Yamada T, Yamano S, Kato M, Kakehashi A, Fujioka M, Tago Y, Kitano M, Wanibuchi H. Diphenylarsinic acid, a chemical warfare-related neurotoxicant, promotes liver carcinogenesis via activation of aryl hydrocarbon receptor signaling and consequent induction of oxidative DAN damage in rats. Toxicol Appl Pharmacol 2013; 273:1-9. [DOI: 10.1016/j.taap.2013.08.022] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 08/20/2013] [Accepted: 08/20/2013] [Indexed: 02/05/2023]
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12
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Genotoxicity and induction of DNA damage responsive genes by food-borne heterocyclic aromatic amines in human hepatoma HepG2 cells. Food Chem Toxicol 2013; 59:386-94. [DOI: 10.1016/j.fct.2013.06.030] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Revised: 06/14/2013] [Accepted: 06/18/2013] [Indexed: 01/07/2023]
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13
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Xie XL, Wei M, Kakehashi A, Yamano S, Okabe K, Tajiri M, Wanibuchi H. Dammar resin, a non-mutagen, inducts oxidative stress and metabolic enzymes in the liver of gpt delta transgenic mouse which is different from a mutagen, 2-amino-3-methylimidazo[4,5-f]quinoline. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2012; 748:29-35. [DOI: 10.1016/j.mrgentox.2012.06.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Revised: 06/06/2012] [Accepted: 06/23/2012] [Indexed: 10/28/2022]
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Wei M, Kakehashi A, Yamano S, Tamano S, Shirai T, Wanibuchi H, Fukushima S. Lack of Hepatocarcinogenicity of Combinations of Low Doses of 2-amino-3, 8-dimethylimidazo[4,5- f ]quinoxaline and Diethylnitrosamine in Rats: Indication for the Existence of a Threshold for Genotoxic Carcinogens. J Toxicol Pathol 2012; 25:209-14. [PMID: 22988339 PMCID: PMC3434336 DOI: 10.1293/tox.25.209] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Accepted: 06/14/2012] [Indexed: 01/20/2023] Open
Abstract
The purposes of the present study were to evaluate the hepatocarcinogenicity of
concurrent treatment of 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline
(MeIQx) and diethylnitrosamine (DEN) in rats and to determine whether no effect levels of
combinations of these two different structural categories of genotoxic hepatocarcinogens
exist. Two 16-week rat hepatocarcinogenesis assays were performed using a total of 790
male F344 rats. In experiment 1, we evaluated the effects of concurrent treatment of a
subcarcinogenic dose of DEN on rat hepatocarcinogenesis induced by various doses of MeIQx.
In experiment 2, we determined hepatocarcinogenicities of combinations of MeIQx and DEN at
subcarcinogenic doses, low carcinogenic doses and high carcinogenic doses. Quantitative
analyses of glutathione S-transferase placental form (GST-P)-positive
foci, a preneoplastic lesion of the liver in rats, revealed that concurrent treatment with
subcarcinogenic doses of DEN did not enhance MeIQx-induced rat hepatocarcinogenicity. We
also found that concurrent treatment with combinations of subcarcinogenic doses of DEN and
MeIQx was not hepatocarcinogenic, indicating that the combined effects of subcarcinogenic
doses of DEN and MeIQx were neither additive nor synergistic. Moreover, concurrent
treatment with low carcinogenic doses of these 2 carcinogens did not show additive or
synergistic effects. Synergetic effects were observed only in rats coadministered high
carcinogenic doses of the 2 carcinogens. These results demonstrate the existence of no
effect levels of combinations of these 2 genotoxic hepatocarcinogens, and provide new
evidence supporting our idea that there is a threshold, at least a practical threshold,
that should be considered when evaluating the risk of genotoxic carcinogens.
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Affiliation(s)
- Min Wei
- Department of Pathology, Osaka City University Graduate School of Medicine, 1-4-3 Asahi-machi, Abeno-ku, Osaka 545-8585, Japan
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Xie XL, Wei M, Kakehashi A, Yamano S, Tajiri M, Wanibuchi H. 2-Amino-3-Methylimidazo[4,5-f]Quinoline (IQ) Promotes Mouse Hepatocarcinogenesis by Activating Transforming Growth Factor- and Wnt/ -Catenin Signaling Pathways. Toxicol Sci 2011; 125:392-400. [DOI: 10.1093/toxsci/kfr314] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
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