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Cox JA, Zwart EP, Luijten M, White PA. The development and prevalidation of an in vitro mutagenicity assay based on MutaMouse primary hepatocytes, Part I: Isolation, structural, genetic, and biochemical characterization. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2019; 60:331-347. [PMID: 30592088 PMCID: PMC6590113 DOI: 10.1002/em.22253] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 09/10/2018] [Accepted: 09/15/2018] [Indexed: 06/09/2023]
Abstract
To develop an improved in vitro mammalian cell gene mutation assay, it is imperative to address the known deficiencies associated with existing assays. Primary hepatocytes isolated from the MutaMouse are ideal for an in vitro gene mutation assay due to their metabolic competence, their "normal" karyotype (i.e., neither transformed nor immortalized), and the presence of the MutaMouse transgene for rapid and reliable mutation scoring. The cells were extensively characterized to confirm their utility. Freshly isolated cells were found to have a hepatocyte-like morphology, predominantly consisting of binucleated cells. These cells maintain hepatocyte-specific markers for up to 3 days in culture. Analyses revealed a normal murine hepatocyte karyotype with a modal ploidy number of 4n. Fluorescence in situ hybridization analysis confirmed the presence of the lambda shuttle vector on chromosome 3. The doubling time was determined to be 22.5 ± 3.3 h. Gene expression and enzymatic activity of key Phase I and Phase II metabolic enzymes were maintained for at least 8 and 24 h in culture, respectively. Exposure to β-naphthoflavone led to approximately 900- and 9-fold increases in Cyp1a1 and Cyp1a2 gene expression, respectively, and approximately twofold induction in cytochrome P450 (CYP) 1A1/1A2 activity. Exposure to phenobarbital resulted in an approximately twofold increase in CYP 2B6 enzyme activity. Following this characterization, it is evident that MutaMouse primary hepatocytes have considerable promise for in vitro mutagenicity assessment. The performance of these cells in an in vitro gene mutation assay is assessed in Part II. Environ. Mol. Mutagen. 60:331-347, 2019. © 2018 The Authors. Environmental and Molecular Mutagenesis published by Wiley Periodicals, Inc. on behalf of Environmental Mutagen Society.
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Affiliation(s)
- Julie A. Cox
- Environmental Health Science and Research Bureau, Health CanadaOttawaOntarioCanada
- Department of BiologyUniversity of OttawaOntarioCanada
| | - Edwin P. Zwart
- Centre for Health ProtectionNational Institute for Public Health and the Environment (RIVM)BilthovenThe Netherlands
| | - Mirjam Luijten
- Centre for Health ProtectionNational Institute for Public Health and the Environment (RIVM)BilthovenThe Netherlands
| | - Paul A. White
- Environmental Health Science and Research Bureau, Health CanadaOttawaOntarioCanada
- Department of BiologyUniversity of OttawaOntarioCanada
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Cox JA, Zwart EP, Luijten M, White PA. The development and prevalidation of an in vitro mutagenicity assay based on MutaMouse primary hepatocytes, Part II: Assay performance for the identification of mutagenic chemicals. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2019; 60:348-360. [PMID: 30714215 PMCID: PMC6593967 DOI: 10.1002/em.22277] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 01/23/2019] [Accepted: 01/29/2019] [Indexed: 06/09/2023]
Abstract
As demonstrated in Part I, cultured MutaMouse primary hepatocytes (PHs) are suitable cells for use in an in vitro gene mutation assay due to their metabolic competence, their "normal" phenotype, and the presence of the MutaMouse transgene for reliable mutation scoring. The performance of these cells in an in vitro gene mutation assay is evaluated in this study, Part II. A panel of 13 mutagenic and nonmutagenic compounds was selected to investigate the performance of the MutaMouse PH in vitro gene mutation assay. The nine mutagens represent a range of classes of chemicals and include mutagens that are both direct-acting and requiring metabolic activation. All the mutagens tested, except for ICR 191, elicited significant, concentration-dependent increases in mutant frequency (MF) ranging from 2.6- to 14.4-fold over the control. None of the four nonmutagens, including two misleading, or "false," positives (i.e., tertiary butylhydroquinone [TBHQ] and eugenol), yielded any significant increases in MF. The benchmark dose covariate approach facilitated ranking of the positive chemicals from most (i.e., 3-nitrobenzanthrone [3-NBA], benzo[a]pyrene [BaP], and aflatoxin B1 [AFB1]) to least (i.e., N-ethyl-N-nitrosourea [ENU]) potent. Overall, the results of this preliminary validation study suggest that this assay may serve as a complimentary tool alongside the standard genotoxicity test battery. This study, alongside Part I, illustrates the promise of MutaMouse PHs for use in an in vitro gene mutation assay, particularly for chemicals requiring metabolic activation. Environ. Mol. Mutagen. 60:348-360, 2019. © 2019 The Authors. Environmental and Molecular Mutagenesis published by Wiley Periodicals, Inc. on behalf of Environmental Mutagen Society.
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Affiliation(s)
- Julie A. Cox
- Environmental Health Science and Research BureauHealth CanadaOttawaOntarioCanada
- Department of BiologyUniversity of OttawaOttawaOntarioCanada
| | - Edwin P. Zwart
- Centre for Health ProtectionNational Institute for Public Health and the Environment (RIVM)BilthovenThe Netherlands
| | - Mirjam Luijten
- Centre for Health ProtectionNational Institute for Public Health and the Environment (RIVM)BilthovenThe Netherlands
| | - Paul A. White
- Environmental Health Science and Research BureauHealth CanadaOttawaOntarioCanada
- Department of BiologyUniversity of OttawaOttawaOntarioCanada
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Tommasi S, Bates SE, Behar RZ, Talbot P, Besaratinia A. Limited mutagenicity of electronic cigarettes in mouse or human cells in vitro. Lung Cancer 2017; 112:41-46. [PMID: 29191599 DOI: 10.1016/j.lungcan.2017.07.035] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 07/25/2017] [Accepted: 07/30/2017] [Indexed: 10/19/2022]
Abstract
OBJECTIVES Electronic cigarettes (e-cig), which are promoted as safe alternatives to tobacco cigarettes or as aides to smoking cessation, are becoming increasingly popular among adult chronic smokers and adolescents experimenting with tobacco products. Despite the known presence of toxicants and carcinogens in e-cig liquid and vapor, the possible carcinogenic effects of e-cig use in humans are unknown. MATERIALS AND METHODS We have utilized two validated in vitro model systems to investigate whether e-cig vapor induces mutation in mouse or human cells. We have exposed transgenic mouse fibroblasts in vitro to e-cig vapor extracts prepared from three popular brands, and determined the induction of mutagenesis in a reporter gene, the cII transgene. Furthermore, we have treated the pSP189 plasmid with e-cig vapor extract, transfected human fibroblast cells with the e-cig-treated plasmid, and screened for the induced mutations in the supF gene. RESULTS AND CONCLUSION We observed no statistically significant increases in relative mutant frequency in the cII transgene or supF gene in the e-cig treated mouse or human cells, respectively. Our data indicate that e-cig vapor extracts from the selected brands and at concentrations tested in this study have limited mutagenicity in both mouse and human cells in vitro.
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Affiliation(s)
- Stella Tommasi
- Department of Preventive Medicine, USC Keck School of Medicine, University of Southern California, M/C 9603, Los Angeles, CA 90033, USA
| | - Steven E Bates
- Department of Cancer Biology, Beckman Research Institute at City of Hope , Duarte, CA, 91010, USA
| | - Rachel Z Behar
- Department of Cell Biology and Neuroscience, University of California, Riverside, CA 92521, USA
| | - Prue Talbot
- Department of Cell Biology and Neuroscience, University of California, Riverside, CA 92521, USA
| | - Ahmad Besaratinia
- Department of Preventive Medicine, USC Keck School of Medicine, University of Southern California, M/C 9603, Los Angeles, CA 90033, USA.
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Holcomb N, Goswami M, Han SG, Clark S, Orren DK, Gairola CG, Mellon I. Exposure of Human Lung Cells to Tobacco Smoke Condensate Inhibits the Nucleotide Excision Repair Pathway. PLoS One 2016; 11:e0158858. [PMID: 27391141 PMCID: PMC4938567 DOI: 10.1371/journal.pone.0158858] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 06/22/2016] [Indexed: 12/19/2022] Open
Abstract
Exposure to tobacco smoke is the number one risk factor for lung cancer. Although the DNA damaging properties of tobacco smoke have been well documented, relatively few studies have examined its effect on DNA repair pathways. This is especially true for the nucleotide excision repair (NER) pathway which recognizes and removes many structurally diverse DNA lesions, including those introduced by chemical carcinogens present in tobacco smoke. The aim of the present study was to investigate the effect of tobacco smoke on NER in human lung cells. We studied the effect of cigarette smoke condensate (CSC), a surrogate for tobacco smoke, on the NER pathway in two different human lung cell lines; IMR-90 lung fibroblasts and BEAS-2B bronchial epithelial cells. To measure NER, we employed a slot-blot assay to quantify the introduction and removal of UV light-induced 6–4 photoproducts and cyclobutane pyrimidine dimers. We find a dose-dependent inhibition of 6–4 photoproduct repair in both cell lines treated with CSC. Additionally, the impact of CSC on the abundance of various NER proteins and their respective RNAs was investigated. The abundance of XPC protein, which is required for functional NER, is significantly reduced by treatment with CSC while the abundance of XPA protein, also required for NER, is unaffected. Both XPC and XPA RNA levels are modestly reduced by CSC treatment. Finally, treatment of cells with MG-132 abrogates the reduction in the abundance of XPC protein produced by treatment with CSC, suggesting that CSC enhances proteasome-dependent turnover of the protein that is mediated by ubiquitination. Together, these findings indicate that tobacco smoke can inhibit the same DNA repair pathway that is also essential for the removal of some of the carcinogenic DNA damage introduced by smoke itself, increasing the DNA damage burden of cells exposed to tobacco smoke.
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Affiliation(s)
- Nathaniel Holcomb
- Department of Toxicology and Cancer Biology, The Markey Cancer Center, University of Kentucky, Lexington, Kentucky, United States of America
| | - Mamta Goswami
- Department of Toxicology and Cancer Biology, The Markey Cancer Center, University of Kentucky, Lexington, Kentucky, United States of America
| | - Sung Gu Han
- Toxicology Laboratory, Department of Food Science and Biotechnology of Animal Resources, College of Animal Bioscience and Technology, Konkuk University, Seoul, Republic of Korea
| | - Samuel Clark
- Department of Toxicology and Cancer Biology, The Markey Cancer Center, University of Kentucky, Lexington, Kentucky, United States of America
| | - David K. Orren
- Department of Toxicology and Cancer Biology, The Markey Cancer Center, University of Kentucky, Lexington, Kentucky, United States of America
| | - C. Gary Gairola
- Department of Toxicology and Cancer Biology, The Markey Cancer Center, University of Kentucky, Lexington, Kentucky, United States of America
| | - Isabel Mellon
- Department of Toxicology and Cancer Biology, The Markey Cancer Center, University of Kentucky, Lexington, Kentucky, United States of America
- * E-mail:
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Scolari F, Gomulski LM, Ribeiro JMC, Siciliano P, Meraldi A, Falchetto M, Bonomi A, Manni M, Gabrieli P, Malovini A, Bellazzi R, Aksoy S, Gasperi G, Malacrida AR. Transcriptional profiles of mating-responsive genes from testes and male accessory glands of the Mediterranean fruit fly, Ceratitis capitata. PLoS One 2012; 7:e46812. [PMID: 23071645 PMCID: PMC3469604 DOI: 10.1371/journal.pone.0046812] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Accepted: 09/05/2012] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Insect seminal fluid is a complex mixture of proteins, carbohydrates and lipids, produced in the male reproductive tract. This seminal fluid is transferred together with the spermatozoa during mating and induces post-mating changes in the female. Molecular characterization of seminal fluid proteins in the Mediterranean fruit fly, Ceratitis capitata, is limited, although studies suggest that some of these proteins are biologically active. METHODOLOGY/PRINCIPAL FINDINGS We report on the functional annotation of 5914 high quality expressed sequence tags (ESTs) from the testes and male accessory glands, to identify transcripts encoding putative secreted peptides that might elicit post-mating responses in females. The ESTs were assembled into 3344 contigs, of which over 33% produced no hits against the nr database, and thus may represent novel or rapidly evolving sequences. Extraction of the coding sequences resulted in a total of 3371 putative peptides. The annotated dataset is available as a hyperlinked spreadsheet. Four hundred peptides were identified with putative secretory activity, including odorant binding proteins, protease inhibitor domain-containing peptides, antigen 5 proteins, mucins, and immunity-related sequences. Quantitative RT-PCR-based analyses of a subset of putative secretory protein-encoding transcripts from accessory glands indicated changes in their abundance after one or more copulations when compared to virgin males of the same age. These changes in abundance, particularly evident after the third mating, may be related to the requirement to replenish proteins to be transferred to the female. CONCLUSIONS/SIGNIFICANCE We have developed the first large-scale dataset for novel studies on functions and processes associated with the reproductive biology of Ceratitis capitata. The identified genes may help study genome evolution, in light of the high adaptive potential of the medfly. In addition, studies of male recovery dynamics in terms of accessory gland gene expression profiles and correlated remating inhibition mechanisms may permit the improvement of pest management approaches.
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Affiliation(s)
- Francesca Scolari
- Department of Biology and Biotechnology, University of Pavia, Pavia, Italy
| | - Ludvik M. Gomulski
- Department of Biology and Biotechnology, University of Pavia, Pavia, Italy
| | - José M. C. Ribeiro
- Section of Vector Biology, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, Rockville, Maryland, United States of America
| | - Paolo Siciliano
- Department of Biology and Biotechnology, University of Pavia, Pavia, Italy
| | - Alice Meraldi
- Department of Biology and Biotechnology, University of Pavia, Pavia, Italy
| | - Marco Falchetto
- Department of Biology and Biotechnology, University of Pavia, Pavia, Italy
| | - Angelica Bonomi
- Department of Biology and Biotechnology, University of Pavia, Pavia, Italy
| | - Mosè Manni
- Department of Biology and Biotechnology, University of Pavia, Pavia, Italy
| | - Paolo Gabrieli
- Department of Biology and Biotechnology, University of Pavia, Pavia, Italy
| | - Alberto Malovini
- IRCCS, Fondazione Salvatore Maugeri, Pavia, Italy
- Istituto Universitario di Studi Superiori (IUSS), Pavia, Italy
- Department of Industrial and Information Engineering, University of Pavia, Pavia, Italy
| | - Riccardo Bellazzi
- Department of Industrial and Information Engineering, University of Pavia, Pavia, Italy
| | - Serap Aksoy
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, Connecticut, United States of America
| | - Giuliano Gasperi
- Department of Biology and Biotechnology, University of Pavia, Pavia, Italy
| | - Anna R. Malacrida
- Department of Biology and Biotechnology, University of Pavia, Pavia, Italy
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Yauk CL, Williams A, Buick JK, Chen G, Maertens RM, Halappanavar S, White PA. Genetic toxicology and toxicogenomic analysis of three cigarette smoke condensates in vitro reveals few differences among full-flavor, blonde, and light products. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2012; 53:281-296. [PMID: 22431010 PMCID: PMC3350776 DOI: 10.1002/em.21689] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/25/2011] [Accepted: 02/09/2012] [Indexed: 05/31/2023]
Abstract
Cigarette smoking leads to various detrimental health outcomes. Tobacco companies produce different brands of cigarettes that are marketed as reduced harm tobacco products. Early examples included "light" cigarettes, which differ from regular cigarettes due to filter ventilation and/or differences in chemical constituents. In order to establish baseline similarities and differences among different tobacco brands available in Canada, the present study examined the cytotoxicity, mutagenicity, clastogenicity, and gene expression profiles of cigarette smoke condensate (CSC) from three tobacco products, encompassing a full-flavor, blonde, and "light" variety. Using the Salmonella mutagenicity assay, we confirmed that the three CSCs are mutagenic, and that the potency is related to the presence of aromatic amines. Using the Muta™Mouse FE1 cell line we determined that the CSCs were clastogenic and cytotoxic, but nonmutagenic, and the results showed few differences in potencies among the three brands. There were no clear brand-specific changes in gene expression; each brand yielded highly similar expression profiles within a time point and concentration. The molecular pathways and biological functions affected by exposure included xenobiotic metabolism, oxidative stress, DNA damage response, cell cycle arrest and apoptosis, as well as inflammation. Thus, there was no appreciable difference in toxicity or gene expression profiles between regular brands and products marketed as "light," and hence no evidence of reduced harm. The work establishes baseline CSC cytotoxicity, mutagenicity, and expression profiles that can be used as a point of reference for comparison with data generated for products marketed as reduced harm and/or modified risk tobacco products.
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Affiliation(s)
- Carole L Yauk
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, Ontario, Canada.
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