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Tennant RE, Guesné SJ, Canipa S, Cayley A, Drewe WC, Honma M, Masumura K, Morita T, Stalford SA, Williams RV. Extrapolation of in vitro structural alerts for mutagenicity to the in vivo endpoint. Mutagenesis 2019; 34:111-121. [PMID: 30281100 DOI: 10.1093/mutage/gey030] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 09/06/2018] [Accepted: 09/12/2018] [Indexed: 11/14/2022] Open
Abstract
As part of the hazard and risk assessment of chemicals in man, it is important to assess the ability of a chemical to induce mutations in vivo. Because of the commonalities in the molecular initiating event, mutagenicity in vitro can correlate well to the in vivo endpoint for certain compound classes; however, the difficulty lies in identifying when this correlation holds true. In silico alerts for in vitro mutagenicity may therefore be used as the basis for alerts for mutagenicity in vivo where an expert assessment is carried out to establish the relevance of the correlation. Taking this into account, a data set of publicly available transgenic rodent gene mutation assay data, provided by the National Institute of Health Sciences of Japan, was processed in the expert system Derek Nexus against the in vitro mutagenicity endpoint. The resulting predictivity was expertly reviewed to assess the validity of the observed correlations in activity and mechanism of action between the two endpoints to identify suitable in vitro alerts for extension to the in vivo endpoint. In total, 20 alerts were extended to predict in vivo mutagenicity, which has significantly improved the coverage of this endpoint in Derek Nexus against the data set provided. Updating the Derek Nexus knowledge base in this way led to an increase in sensitivity for this data set against this endpoint from 9% to 66% while maintaining a good specificity of 89%.
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Affiliation(s)
| | | | | | - Alex Cayley
- Lhasa Limited, Granary Wharf House, Leeds, UK
| | | | - Masamitsu Honma
- National Institute of Health Sciences, Kawasaki-ku, Kanagawa, Japan
| | - Kenichi Masumura
- National Institute of Health Sciences, Kawasaki-ku, Kanagawa, Japan
| | - Takeshi Morita
- National Institute of Health Sciences, Kawasaki-ku, Kanagawa, Japan
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Environmental exposure of humans to bromide in the Dead Sea area: Measurement of genotoxicy and apoptosis biomarkers. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2018; 837:34-41. [PMID: 30595207 DOI: 10.1016/j.mrgentox.2018.09.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Revised: 09/19/2018] [Accepted: 09/21/2018] [Indexed: 01/20/2023]
Abstract
Bromide (Br-) is a bromine atom with a negative charge which is released mainly in the production of pesticides and flame retardants. It is also found naturally in seawater. Br¯ has been associated with many detrimental effects such as respiratory problems, gastric hemorrhages, and dermal burns. The aim of the study was to monitor serum bromide in humans and to correlate its level with genotoxicity and apoptosis in human. The study utilized comet assay, to measure DNA damage in peripheral leukocytes (i.e. T%DNA), enzyme-linked immunosorbent assay were used to determine fortilin level as an apoptosis marker, and spectrophotometry to measure serum Br¯ in two populations at the Dead Sea area, which are located close to and far from a local bromine factory: Ghor As-safi and Deir Alla, respectively. The biomarkers were compared with the correlating serum Br¯. A total of 397 individuals were involved in the study. The serum Br- and the genotoxicity biomarker were significantly higher (p < 0.001) in Ghor As-safi than in Deir Alla. In contrast, serum fortilin did not differ significantly between the two regions (p > 0.05). T%DNA was significantly correlated (r = 0.867, p < 0.01) to serum Br¯. In conclusion, residing near a bromide source site is increasing the bromide body burden, and enhancing genotoxicity with no detectible apoptosis. Furthermore, the selected biomarkers could serve as tools to assess the toxicity of bromide as a consequence of environmental exposure.
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Hutchings ML, Alpha-Cobb CJ, Hiller DA, Berro J, Strobel SA. Mycofumigation through production of the volatile DNA-methylating agent N-methyl- N-nitrosoisobutyramide by fungi in the genus Muscodor. J Biol Chem 2017; 292:7358-7371. [PMID: 28283571 DOI: 10.1074/jbc.m117.779009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 03/05/2017] [Indexed: 01/31/2023] Open
Abstract
Antagonistic microorganisms produce antimicrobials to inhibit the growth of competitors. Although water-soluble antimicrobials are limited to proximal interactions via aqueous diffusion, volatile antimicrobials are able to act at a distance and diffuse through heterogeneous environments. Here, we identify the mechanism of action of Muscodor albus, an endophytic fungus known for its volatile antimicrobial activity toward a wide range of human and plant pathogens and its potential use in mycofumigation. Proposed uses of the Muscodor species include protecting crops, produce, and building materials from undesired fungal or bacterial growth. By analyzing a collection of Muscodor isolates with varying toxicity, we demonstrate that the volatile mycotoxin, N-methyl-N-nitrosoisobutyramide, is the dominant factor in Muscodor toxicity and acts primarily through DNA methylation. Additionally, Muscodor isolates exhibit higher resistance to DNA methylation compared with other fungi. This work contributes to the evaluation of Muscodor isolates as potential mycofumigants, provides insight into chemical strategies that organisms use to manipulate their environment, and provokes questions regarding the mechanisms of resistance used to tolerate constitutive, long-term exposure to DNA methylation.
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Affiliation(s)
| | | | - David A Hiller
- Molecular Biophysics and Biochemistry, Chemical Biology Institute, and
| | - Julien Berro
- Department of Molecular Biophysics and Biochemistry, Nanobiology Institute, Yale University, West Haven, Connecticut 06516
| | - Scott A Strobel
- Molecular Biophysics and Biochemistry, Chemical Biology Institute, and
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Wang C, Zhang Z, Yao H, Zhao F, Wang L, Wang X, Xing H, Xu S. Effects of atrazine and chlorpyrifos on DNA methylation in the liver, kidney and gill of the common carp (Cyprinus carpio L.). ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2014; 108:142-51. [PMID: 25062446 DOI: 10.1016/j.ecoenv.2014.06.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2014] [Revised: 06/08/2014] [Accepted: 06/09/2014] [Indexed: 05/28/2023]
Abstract
Pesticide exposure has repeatedly been associated with cancers, although the molecular mechanisms behind this association are largely undetermined. Abnormal DNA methylation plays a key role in the process of some disease. However, little was known about the effect of pesticides on DNA methylation in the common carp. In this study, we investigated the mRNA levels of DNA methyltransferases (DNMTs) and methyl-CpG-binding protein DNA-binding domain protein 2 (MBD2) as well as the DNA methylation levels in the liver, kidney and gill of the common carp (Cyprinus carpio L.) after 40-d exposure to atrazine (ATR) and chlorpyrifos (CPF) alone or in combination, and a 40-d recovery period. Juvenile common carp were exposed to various concentrations of ATR (at concentrations of 4.28, 42.8 and 428μg/L), CPF (1.16, 11.6 and 116μg/L), and an ATR/CPF mixture (at concentrations of 1.13, 11.3 and 113μg/L). The results revealed that the levels of genomic DNA methylation decreased in all tissues after 40d of exposure to ATR and CPF either individually or in combination. Moreover, the mRNA expression of DNMTs was down-regulated in all treatment groups. In contrast, the mRNA expression of MBD2 was up-regulated. These results demonstrated that long-term exposure to ATR, CPF and ATR/CPF mixtures could disrupt genomic DNA. It might imply that DNA methylation is involved in the toxicity caused by ATR and CPF in the common carp.
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Affiliation(s)
- Chao Wang
- Department of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China
| | - Ziwei Zhang
- Department of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China
| | - Haidong Yao
- Department of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China
| | - Fuqing Zhao
- Department of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China
| | - Liangliang Wang
- Department of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China
| | - Xiaolong Wang
- Center of conservation medicine & ecological safety, Northeast Forestry University, Harbin, 150040, PR China.
| | - Houjuan Xing
- Animal Health Supervision Institute of Heilongjiang Province, Harbin 150069, PR China.
| | - Shiwen Xu
- Department of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China.
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Alavanja MCR, Ross MK, Bonner MR. Increased cancer burden among pesticide applicators and others due to pesticide exposure. CA Cancer J Clin 2013; 63:120-42. [PMID: 23322675 DOI: 10.3322/caac.21170] [Citation(s) in RCA: 181] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
A growing number of well-designed epidemiological and molecular studies provide substantial evidence that the pesticides used in agricultural, commercial, and home and garden applications are associated with excess cancer risk. This risk is associated both with those applying the pesticide and, under some conditions, those who are simply bystanders to the application. In this article, the epidemiological, molecular biology, and toxicological evidence emerging from recent literature assessing the link between specific pesticides and several cancers including prostate cancer, non-Hodgkin lymphoma, leukemia, multiple myeloma, and breast cancer are integrated. Although the review is not exhaustive in its scope or depth, the literature does strongly suggest that the public health problem is real. If we are to avoid the introduction of harmful chemicals into the environment in the future, the integrated efforts of molecular biology, pesticide toxicology, and epidemiology are needed to help identify the human carcinogens and thereby improve our understanding of human carcinogenicity and reduce cancer risk.
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Affiliation(s)
- Michael C R Alavanja
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, North Bethesda, MD 20892, USA.
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Budnik LT, Kloth S, Velasco-Garrido M, Baur X. Prostate cancer and toxicity from critical use exemptions of methyl bromide: environmental protection helps protect against human health risks. Environ Health 2012; 11:5. [PMID: 22284215 PMCID: PMC3807750 DOI: 10.1186/1476-069x-11-5] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2011] [Accepted: 01/27/2012] [Indexed: 05/29/2023]
Abstract
BACKGROUND Although ozone-depleting methyl bromide was destined for phase-out by 2005, it is still widely applied as a consequence of various critical-use-exemptions and mandatory international regulations aiming to restrict the spread of pests and alien species (e.g. in globalized transport and storage). The withdrawal of methyl bromide because of its environmental risk could fortuitously help in the containment of its human toxicity. METHODS We performed a systematic review of the literature, including in vitro toxicological and epidemiological studies of occupational and community exposure to the halogenated hydrocarbon pesticide methyl bromide. We focused on toxic (especially chronic) or carcinogenic effects from the use of methyl bromide, on biomonitoring data and reference values. Eligible epidemiological studies were subjected to meta-analysis. RESULTS Out of the 542 peer reviewed publications between 1990-2011, we found only 91 referring to toxicity of methyl bromide and 29 using the term "carcinogenic", "neoplastic" or "mutagenic". Several studies provide new additional data pertaining to the mechanistic aspects of methyl bromide toxicity. Few studies have performed a detailed exposure assessment including biomonitoring. Three evaluated epidemiological studies assessed a possible association between cancer and methyl bromide. Overall, exposure to methyl bromide is associated with an increased risk of prostate cancer OR, 1.21; 95% CI (0,98-1.49), P = 0.076. Two epidemiological studies have analyzed environmental, non-occupational exposure to methyl bromide providing evidence for its health risk to the general public. None of the epidemiological studies addressed its use as a fumigant in freight containers, although recent field and case reports do refer to its toxic effects associated with its use in shipping and storage. CONCLUSIONS Both the epidemiological evidence and toxicological data suggest a possible link between methyl bromide exposure and serious health problems, including prostate cancer risk from occupational and community exposure. The environmental risks of methyl bromide are not in doubt, but also its health risks, especially for genetically predisposed subjects, should not be underestimated.
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Affiliation(s)
- Lygia T Budnik
- Division of Occupational Toxicology and Immunology, Institute for Occupational and Maritime Medicine (ZfAM), Medical Faculty, University of Hamburg, University Medical Center, Hamburg, Germany
| | - Stefan Kloth
- Division of Occupational Toxicology and Immunology, Institute for Occupational and Maritime Medicine (ZfAM), Medical Faculty, University of Hamburg, University Medical Center, Hamburg, Germany
| | - Marcial Velasco-Garrido
- Division of Clinical Occupational Medicine, Institute for Occupational and Maritime Medicine (ZfAM), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Xaver Baur
- Chair for Occupational Medicine, Medical Faculty, University of Hamburg, University Medical Center, Hamburg, Germany
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Cockburn M, Mills P, Zhang X, Zadnick J, Goldberg D, Ritz B. Prostate cancer and ambient pesticide exposure in agriculturally intensive areas in California. Am J Epidemiol 2011; 173:1280-8. [PMID: 21447478 DOI: 10.1093/aje/kwr003] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
In a population-based case-control study in California's intensely agricultural Central Valley (2005-2006), the authors investigated relations between environmental pesticide/fungicide exposure and prostate cancer. Cases (n = 173) were obtained from a population-based cancer registry, and controls (n = 162) were obtained from Medicare listings and tax assessor mailings. Past ambient exposures to pesticides/fungicides were derived from residential history and independently recorded pesticide and land-use data, using a novel geographic information systems approach. In comparison with unexposed persons, increased risks of prostate cancer were observed among persons exposed to compounds which may have prostate-specific biologic effects (methyl bromide (odds ratio = 1.62, 95% confidence interval: 1.02, 2.59) and a group of organochlorines (odds ratio = 1.64, 95% confidence interval: 1.02, 2.63)) but not among those exposed to other compounds that were included as controls (simazine, maneb, and paraquat dichloride). The authors assessed the possibility of selection bias due to less-than-100% enrollment of eligible cases and controls (a critical methodological concern in studies of this kind) and determined that there was little evidence of bias affecting the estimated effect size. This study provides evidence of an association between prostate cancer and ambient pesticide exposures in and around homes in intensely agricultural areas. The associations appear specific to compounds with a plausible biologic role in prostate carcinogenesis.
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Affiliation(s)
- Myles Cockburn
- Department of Preventive Medicine, Keck School of Medicine, University of Southern California, 1441 Eastlake Avenue, Los Angeles, CA 90089-9175, USA.
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Opinion of the Scientific Panel on Plant protection products and their residues (PPR) related to the evaluation of dichlorvos in the context of Council Directive 91/414/EEC. EFSA J 2006. [DOI: 10.2903/j.efsa.2006.343] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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Lambert IB, Singer TM, Boucher SE, Douglas GR. Detailed review of transgenic rodent mutation assays. Mutat Res 2005; 590:1-280. [PMID: 16081315 DOI: 10.1016/j.mrrev.2005.04.002] [Citation(s) in RCA: 247] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2005] [Revised: 04/04/2005] [Accepted: 04/12/2005] [Indexed: 11/17/2022]
Abstract
Induced chromosomal and gene mutations play a role in carcinogenesis and may be involved in the production of birth defects and other disease conditions. While it is widely accepted that in vivo mutation assays are more relevant to the human condition than are in vitro assays, our ability to evaluate mutagenesis in vivo in a broad range of tissues has historically been quite limited. The development of transgenic rodent (TGR) mutation models has given us the ability to detect, quantify, and sequence mutations in a range of somatic and germ cells. This document provides a comprehensive review of the TGR mutation assay literature and assesses the potential use of these assays in a regulatory context. The information is arranged as follows. (1) TGR mutagenicity models and their use for the analysis of gene and chromosomal mutation are fully described. (2) The principles underlying current OECD tests for the assessment of genotoxicity in vitro and in vivo, and also nontransgenic assays available for assessment of gene mutation, are described. (3) All available information pertaining to the conduct of TGR assays and important parameters of assay performance have been tabulated and analyzed. (4) The performance of TGR assays, both in isolation and as part of a battery of in vitro and in vivo short-term genotoxicity tests, in predicting carcinogenicity is described. (5) Recommendations are made regarding the experimental parameters for TGR assays, and the use of TGR assays in a regulatory context.
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Affiliation(s)
- Iain B Lambert
- Mutagenesis Section, Environmental Health Sciences Bureau, Healthy Environments and Consumer Safety Branch, 0803A, Health Canada, Ottawa, Ont., Canada K1A 0L2.
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Wahnschaffe U, Bitsch A, Kielhorn J, Mangelsdorf I. Mutagenicity testing with transgenic mice. Part I: Comparison with the mouse bone marrow micronucleus test. J Carcinog 2005; 4:3. [PMID: 15655069 PMCID: PMC548135 DOI: 10.1186/1477-3163-4-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2004] [Accepted: 01/17/2005] [Indexed: 11/20/2022] Open
Abstract
As part of a larger literature study on transgenic animals in mutagenicity testing, test results from the transgenic mutagenicity assays (lacI model; commercially available as the Big Blue(R) mouse, and the lacZ model; commercially available as the Mutatrade markMouse), were compared with the results on the same substances in the more traditional mouse bone marrow micronucleus test. 39 substances were found which had been tested in the micronucleus assay and in the above transgenic mouse systems. Although, the transgenic animal mutation assay is not directly comparable with the micronucleus test, because different genetic endpoints are examined: chromosome aberration versus gene mutation, the results for the majority of substances were in agreement. Both test systems, the transgenic mouse assay and the mouse bone marrow micronucleus test, have advantages and they complement each other. However, the transgenic animal assay has some distinct advantages over the micronucleus test: it is not restricted to one target organ and detects systemic as well as local mutagenic effects.
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Affiliation(s)
- U Wahnschaffe
- Fraunhofer Institute of Toxicology and Experimental Medicine ITEM, Department of Chemical Risk Assessment, Nikolai-Fuchs-Str. 1, 30625 Hannover, Germany
| | - A Bitsch
- Fraunhofer Institute of Toxicology and Experimental Medicine ITEM, Department of Chemical Risk Assessment, Nikolai-Fuchs-Str. 1, 30625 Hannover, Germany
| | - J Kielhorn
- Fraunhofer Institute of Toxicology and Experimental Medicine ITEM, Department of Chemical Risk Assessment, Nikolai-Fuchs-Str. 1, 30625 Hannover, Germany
| | - I Mangelsdorf
- Fraunhofer Institute of Toxicology and Experimental Medicine ITEM, Department of Chemical Risk Assessment, Nikolai-Fuchs-Str. 1, 30625 Hannover, Germany
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Abstract
The predominant pathway for the repair of O(6)-methylguanine in DNA is via the activity of an alkyltransferase protein that transfers the methyl group to a cysteine acceptor site on the protein itself. This review article describes recent studies on this alkyltransferase. The protein repairs not only methyl groups but also 2-chloroethyl-, benzyl- and pyridyloxobutyl-adducts. It acts on double-stranded DNA by flipping the O(6)-guanine adduct out of the DNA helix and into a binding pocket. The free base, O(6)-benzylguanine, is able to bind in this pocket and react with the cysteine, rendering it an effective inactivator of mammalian alkyltransferases. The alkylated form of the protein is rapidly degraded by the ubiquitin/proteasomal system. Some tumor cells do not express alkyltransferase despite having an intact gene. Methylation of key sites in CpG-rich islands in the promoter region are involved in this silencing and a change in the nuclear localization of an enhancer binding protein may also contribute. The alkyltransferase promoter contains Sp1, GRE and AP-1 sites and is slightly inducible by glucocorticoids and protein kinase C activators. There is a complex relationship between p53 and alkyltransferase expression with p53 mediating a rise in alkyltransferase in response to ionizing radiation but having no clear effect on basal levels. DNA adducts at the O(6)-position of guanine are a major factor in the carcinogenic, mutagenic, apoptopic and clastogenic actions of methylating agents and chloroethylating agents. Studies with transgenic mice in which alkyltransferase levels are increased or decreased confirm the importance of this repair pathway in protecting against carcinogenesis. Alkyltransferase activity in tumors protects them from therapeutic agents such as temozolomide and BCNU. This resistance is abolished by O(6)-benzylguanine and this drug is currently in clinical trials to enhance cancer chemotherapy by these agents. Studies are in progress to reduce the toxicity of such therapy towards the bone marrow by gene therapy to express alkyltransferases with mutations imparting resistance to O(6)-benzylguanine at high levels in marrow stem cells. Several polymorphisms in the human alkyltransferase gene have been identified but the significance of these in terms of alkyltransferase action is currently unknown.
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Affiliation(s)
- A E Pegg
- Departments of Cellular and Molecular Physiology and Pharmacology, Milton S. Hershey Medical Center, Pennsylvania State University College of Medicine, P.O. Box 850, 500 University Drive, Hershey, PA, USA.
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Pletsa V, Steenwinkel MJ, van Delft JH, Baan RA, Kyrtopoulos SA. Induction of somatic mutations but not methylated DNA adducts in lambdalacZ transgenic mice by dichlorvos. Cancer Lett 1999; 146:155-60. [PMID: 10656620 DOI: 10.1016/s0304-3835(99)00256-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In order to examine the in vivo genotoxic activity of dichlorvos, lambdalacZ transgenic mice (Muta Mouse) were treated i.p. with single (4.4 or 11 mg/kg) or multiple (5 x 11 mg/kg) doses of this agent and sacrificed 4 h or 14 days post-treatment for DNA adduct measurement or mutant frequency analysis, respectively. Neither methylated DNA adducts nor an increase in mutant frequency were detected in the bone marrow, white blood cells, liver, spleen, lung, brain and sperm cells after the single doses. However, following multiple dosing a statistically significant 3-fold increase in mutant frequency was observed in the liver, while a non-statistically significant increase was observed in the bone marrow. In contrast, dimethylsulphate, a model methylating agent, gave rise to detectable DNA adducts but no increase in mutant frequency following i.p. administration of single (30 mg/kg) or multiple (10 x 6 mg/kg) doses.
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Affiliation(s)
- V Pletsa
- Laboratory of Chemical Carcinogenesis, Institute of Biological Research and Biotechnology, National Hellenic Research Foundation, Athens, Greece
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