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Kelty J, Kovalchuk N, Uwimana E, Yin L, Ding X, Van Winkle L. In vitro airway models from mice, rhesus macaques, and humans maintain species differences in xenobiotic metabolism and cellular responses to naphthalene. Am J Physiol Lung Cell Mol Physiol 2022; 323:L308-L328. [PMID: 35853015 PMCID: PMC9423729 DOI: 10.1152/ajplung.00349.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 04/04/2022] [Accepted: 07/01/2022] [Indexed: 11/22/2022] Open
Abstract
The translational value of high-throughput toxicity testing will depend on pharmacokinetic validation. Yet, popular in vitro airway epithelia models were optimized for structure and mucociliary function without considering the bioactivation or detoxification capabilities of lung-specific enzymes. This study evaluated xenobiotic metabolism maintenance within differentiated air-liquid interface (ALI) airway epithelial cell cultures (human bronchial; human, rhesus, and mouse tracheal), isolated airway epithelial cells (human, rhesus, and mouse tracheal; rhesus bronchial), and ex vivo microdissected airways (rhesus and mouse) by measuring gene expression, glutathione content, and naphthalene metabolism. Glutathione levels and detoxification gene transcripts were measured after 1-h exposure to 80 µM naphthalene (a bioactivated toxicant) or reactive naphthoquinone metabolites. Glutathione and glutathione-related enzyme transcript levels were maintained in ALI cultures from all species relative to source tissues, while cytochrome P450 monooxygenase gene expression declined. Notable species differences among the models included a 40-fold lower total glutathione content for mouse ALI trachea cells relative to human and rhesus; a higher rate of naphthalene metabolism in mouse ALI cultures for naphthalene-glutathione formation (100-fold over rhesus) and naphthalene-dihydrodiol production (10-fold over human); and opposite effects of 1,2-naphthoquinone exposure in some models-glutathione was depleted in rhesus tissue but rose in mouse ALI samples. The responses of an immortalized bronchial cell line to naphthalene and naphthoquinones were inconsistent with those of human ALI cultures. These findings of preserved species differences and the altered balance of phase I and phase II xenobiotic metabolism among the characterized in vitro models should be considered for future pulmonary toxicity testing.
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Affiliation(s)
- Jacklyn Kelty
- Department of Anatomy, Physiology and Cell Biology, Center for Comparative Respiratory Biology and Medicine, School of Veterinary Medicine and Center for Health and the Environment, University of California at Davis, Davis, California
| | - Nataliia Kovalchuk
- Pharmacology and Toxicology Department, College of Pharmacy, University of Arizona, Tucson, Arizona
| | - Eric Uwimana
- Pharmacology and Toxicology Department, College of Pharmacy, University of Arizona, Tucson, Arizona
| | - Lei Yin
- Pharmacology and Toxicology Department, College of Pharmacy, University of Arizona, Tucson, Arizona
| | - Xinxin Ding
- Pharmacology and Toxicology Department, College of Pharmacy, University of Arizona, Tucson, Arizona
| | - Laura Van Winkle
- Department of Anatomy, Physiology and Cell Biology, Center for Comparative Respiratory Biology and Medicine, School of Veterinary Medicine and Center for Health and the Environment, University of California at Davis, Davis, California
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Soares AG, Muscara MN, Costa SKP. Molecular mechanism and health effects of 1,2-Naphtoquinone. EXCLI JOURNAL 2020; 19:707-717. [PMID: 32636724 PMCID: PMC7332801 DOI: 10.17179/excli2020-1210] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 05/25/2020] [Indexed: 12/25/2022]
Abstract
Extensive literature regarding the health side effects of ambient pollutants (AP) are available, such as diesel exhaust particles (DEPs), but limited studies are available on their electrophilic contaminant 1,2-Naphthoquinone (1,2-NQ), enzymatically derived from naphthalene. This review summarizes relevant toxicologic and biological properties of 1,2-NQ as an environmental pollutant or to a lesser degree as a backbone in drug development to treat infectious diseases. It presents evidence of 1,2-NQ-mediated genotoxicity, neurogenic inflammation, and cytotoxicity due to several mechanistic properties, including the production of reactive oxygen species (ROS), that promote cell damage, carcinogenesis, and cell death. Many signal transduction pathways act as a vulnerable target for 1,2-NQ, including kappaB kinase b (IKKbeta) and protein tyrosine phosphatase 1B (PTP1B). Antioxidant molecules act in defense against ROS/RNS-mediated 1,2-NQ responses to injury. Nonetheless, its inhibitory effects at PTP1B, altering the insulin signaling pathway, represents a new therapeutic target to treat diabetes type 2. Questions exist whether exposure to 1,2-NQ may promote arylation of the Keap1 factor, a negative regulator of Nrf2, as well as acting on the sepiapterin reductase activity, an NADPH-dependent enzyme which catalyzes the formation of critical cofactors in aromatic amino acid metabolism and nitric oxide biosynthesis. Exposure to 1,2-NQ is linked to neurologic, behavioral, and developmental disturbances as well as increased susceptibility to asthma. Limited new knowledge exists on molecular modeling of quinones molecules as antitumoral and anti-microorganism agents. Altogether, these studies suggest that 1,2-NQ and its intermediate compounds can initiate a number of pathological pathways as AP in living organisms but it can be used to better understand molecular pathways.
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Affiliation(s)
- Antonio G Soares
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, USA. 7703 Floyd Curl Dr. San Antonio, TX, USA 78229.,Laboratory of Biochemical Pharmacology of Free Radicals, Inflammation and Pain, Departamento de Farmacologia, Instituto de Ciencias Biomedicas (ICB), University of Sao Paulo, Brazil. Av. Prof Lineu Prestes, 1524 Cidade Universitaria, Sao Paulo, SP CEP 05508-000, Brazil
| | - Marcelo N Muscara
- Laboratory of Biochemical Pharmacology of Free Radicals, Inflammation and Pain, Departamento de Farmacologia, Instituto de Ciencias Biomedicas (ICB), University of Sao Paulo, Brazil. Av. Prof Lineu Prestes, 1524 Cidade Universitaria, Sao Paulo, SP CEP 05508-000, Brazil
| | - Soraia K P Costa
- Laboratory of Biochemical Pharmacology of Free Radicals, Inflammation and Pain, Departamento de Farmacologia, Instituto de Ciencias Biomedicas (ICB), University of Sao Paulo, Brazil. Av. Prof Lineu Prestes, 1524 Cidade Universitaria, Sao Paulo, SP CEP 05508-000, Brazil
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Carratt SA, Hartog M, Buchholz BA, Kuhn EA, Collette NM, Ding X, Van Winkle LS. Naphthalene genotoxicity: DNA adducts in primate and mouse airway explants. Toxicol Lett 2019; 305:103-109. [PMID: 30684585 DOI: 10.1016/j.toxlet.2019.01.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 01/05/2019] [Accepted: 01/20/2019] [Indexed: 01/14/2023]
Abstract
Naphthalene (NA) is a ubiquitous environmental pollutant and possible human carcinogen that forms tumors in rodents with tissue/regional and species selectivity. This study seeks to determine whether NA is able to directly adduct DNA in an ex vivo culture system. Metabolically active lung tissue was isolated and incubated in explant culture with carbon-14 labeled NA (0, 25, 250 μM) or 1,2-naphthoquinone (NQ), followed by AMS analyses of metabolite binding to DNA. Despite relatively low metabolic bioactivation in the primate airway, dose-dependent NA-DNA adduct formation was detected. More airway adducts were detected in female mice (4.7-fold) and primates (2.1-fold) than in males of the same species. Few adducts were detected in rat airway or nasal epithelium. NQ, which is a metabolic product of NA, proved to be even more potent, with levels of adduct formation 70-80-fold higher than seen when tissues were incubated with the parent compound NA. This is the first study to demonstrate NA-DNA adduct formation at a site of carcinogenesis, the mouse lung. Adducts were also detected in non-human primate lung and with a NQ metabolite of NA. Taken together, this suggests that NA may contribute to in vivo carcinogenesis through a genotoxic mechanism.
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Affiliation(s)
- Sarah A Carratt
- Center for Health and the Environment, University of California Davis, Davis, CA 95616, USA
| | - Matthew Hartog
- College of Nanoscale Science and Engineering, SUNY Polytechnic Institute, Albany, NY 12203, USA
| | - Bruce A Buchholz
- Lawrence Livermore National Laboratory, Livermore, CA 94551, USA
| | - Edward A Kuhn
- Lawrence Livermore National Laboratory, Livermore, CA 94551, USA
| | | | - Xinxin Ding
- College of Nanoscale Science and Engineering, SUNY Polytechnic Institute, Albany, NY 12203, USA.
| | - Laura S Van Winkle
- Center for Health and the Environment, University of California Davis, Davis, CA 95616, USA; Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California Davis, Davis, CA 95616, USA.
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4
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Enerstvedt KS, Sydnes MO, Larssen E, Pampanin DM. Screening for protein adducts of naphthalene and chrysene in plasma of exposed Atlantic cod (Gadus morhua). CHEMOSPHERE 2018; 200:67-79. [PMID: 29475030 DOI: 10.1016/j.chemosphere.2018.02.091] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 02/14/2018] [Accepted: 02/15/2018] [Indexed: 06/08/2023]
Abstract
Polycyclic aromatic hydrocarbons (PAHs) are well known contaminants, ubiquitously present in the habitat and spawning areas for Atlantic cod (Gadus morhua). The Atlantic cod is a key species and a globally important food source, thus continuous monitoring of PAHs is considered highly valuable to ensure ecosystem sustainability and human food safety. PAH adducts to plasma proteins are applied as sensitive biomarkers of PAH exposure in humans and other species, thus the presence of PAH protein adducts in Atlantic cod plasma was investigated to identify PAH protein adduct biomarker candidates of exposure to PAHs. Blood plasma samples were collected from Atlantic cod (n = 66) one week after exposure by intramuscular injection of single PAHs (i.e. naphthalene and chrysene), and their corresponding dihydrodiol metabolites (i.e. (-)-(1R,2R)-1,2-dihydronaphthalene-1,2-diol and (-)-(1R,2R)-1,2-dihydrochrysene-1,2-diol). The samples were analyzed by shotgun tandem mass spectrometry (MS) and the resulting MS data were analyzed in Byonic™ to screen for proteins susceptible to adduct formation with naphthalene and chrysene. Furthermore, a wildcard modification search was performed to obtain additional information regarding potential modifications other than the targeted metabolites. The amino acid adductation sites and the metabolites involved in PAH adductation are reported. Forty-four proteins were found to bind PAHs. Alpha-2-macroglobulin-like proteins, apolipoproteins B-100-like proteins and an alpha-2-HS-glycoprotein were detected with the highest number of bound PAHs. This first insight into PAH protein adducts of Atlantic cod plasma generates valuable knowledge for the development of highly sensitive biomarkers of PAH exposure.
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Affiliation(s)
- Karianne S Enerstvedt
- International Research Institute of Stavanger (IRIS) - Environment Department, Mekjarvik 12, NO-4070 Randaberg, Norway; Faculty of Science and Technology, Department of Mathematics and Natural Science, University of Stavanger, NO-4036 Stavanger, Norway
| | - Magne O Sydnes
- Faculty of Science and Technology, Department of Mathematics and Natural Science, University of Stavanger, NO-4036 Stavanger, Norway
| | - Eivind Larssen
- International Research Institute of Stavanger (IRIS) - Environment Department, Mekjarvik 12, NO-4070 Randaberg, Norway
| | - Daniela M Pampanin
- International Research Institute of Stavanger (IRIS) - Environment Department, Mekjarvik 12, NO-4070 Randaberg, Norway; Faculty of Science and Technology, Department of Mathematics and Natural Science, University of Stavanger, NO-4036 Stavanger, Norway.
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5
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Yip VLM, Meng X, Maggs JL, Jenkins RE, Marlot PT, Marson AG, Park BK, Pirmohamed M. Mass Spectrometric Characterization of Circulating Covalent Protein Adducts Derived from Epoxide Metabolites of Carbamazepine in Patients. Chem Res Toxicol 2017; 30:1419-1435. [DOI: 10.1021/acs.chemrestox.7b00063] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Vincent L. M. Yip
- MRC
Centre for Drug Safety Science, Department of Molecular and Clinical
Pharmacology, The University of Liverpool, Liverpool L69 3GE, United Kingdom
- The
Wolfson Centre for Personalized Medicine, Department of Molecular
and Clinical Pharmacology, The University of Liverpool, Liverpool L69 3GL, United Kingdom
| | - Xiaoli Meng
- MRC
Centre for Drug Safety Science, Department of Molecular and Clinical
Pharmacology, The University of Liverpool, Liverpool L69 3GE, United Kingdom
| | - James L. Maggs
- MRC
Centre for Drug Safety Science, Department of Molecular and Clinical
Pharmacology, The University of Liverpool, Liverpool L69 3GE, United Kingdom
| | - Rosalind E. Jenkins
- MRC
Centre for Drug Safety Science, Department of Molecular and Clinical
Pharmacology, The University of Liverpool, Liverpool L69 3GE, United Kingdom
| | - Philippe T. Marlot
- MRC
Centre for Drug Safety Science, Department of Molecular and Clinical
Pharmacology, The University of Liverpool, Liverpool L69 3GE, United Kingdom
- The
Wolfson Centre for Personalized Medicine, Department of Molecular
and Clinical Pharmacology, The University of Liverpool, Liverpool L69 3GL, United Kingdom
| | - Anthony G. Marson
- MRC
Centre for Drug Safety Science, Department of Molecular and Clinical
Pharmacology, The University of Liverpool, Liverpool L69 3GE, United Kingdom
| | - B. Kevin Park
- MRC
Centre for Drug Safety Science, Department of Molecular and Clinical
Pharmacology, The University of Liverpool, Liverpool L69 3GE, United Kingdom
| | - Munir Pirmohamed
- MRC
Centre for Drug Safety Science, Department of Molecular and Clinical
Pharmacology, The University of Liverpool, Liverpool L69 3GE, United Kingdom
- The
Wolfson Centre for Personalized Medicine, Department of Molecular
and Clinical Pharmacology, The University of Liverpool, Liverpool L69 3GL, United Kingdom
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Bailey LA, Nascarella MA, Kerper LE, Rhomberg LR. Hypothesis-based weight-of-evidence evaluation and risk assessment for naphthalene carcinogenesis. Crit Rev Toxicol 2015; 46:1-42. [PMID: 26202831 PMCID: PMC4732411 DOI: 10.3109/10408444.2015.1061477] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Accepted: 06/09/2015] [Indexed: 11/13/2022]
Abstract
Inhalation of naphthalene causes olfactory epithelial nasal tumors in rats (but not in mice) and benign lung adenomas in mice (but not in rats). The limited available human data have not identified an association between naphthalene exposure and increased respiratory cancer risk. Assessing naphthalene's carcinogenicity in humans, therefore, depends entirely on experimental evidence from rodents. We evaluated the respiratory carcinogenicity of naphthalene in rodents, and its potential relevance to humans, using our Hypothesis-Based Weight-of-Evidence (HBWoE) approach. We systematically and comparatively reviewed data relevant to key elements in the hypothesized modes of action (MoA) to determine which is best supported by the available data, allowing all of the data from each realm of investigation to inform interpretation of one another. Our analysis supports a mechanism that involves initial metabolism of naphthalene to the epoxide, followed by GSH depletion, cytotoxicity, chronic inflammation, regenerative hyperplasia, and tumor formation, with possible weak genotoxicity from downstream metabolites occurring only at high cytotoxic doses, strongly supporting a non-mutagenic threshold MoA in the rat nose. We also conducted a dose-response analysis, based on the likely MoA, which suggests that the rat nasal MoA is not relevant in human respiratory tissues at typical environmental exposures. Our analysis illustrates how a thorough WoE evaluation can be used to support a MoA, even when a mechanism of action cannot be fully elucidated. A non-mutagenic threshold MoA for naphthalene-induced rat nasal tumors should be considered as a basis to determine human relevance and to guide regulatory and risk-management decisions.
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Characterization of quinone derived protein adducts and their selective identification using redox cycling based chemiluminescence assay. J Chromatogr A 2015; 1403:96-103. [PMID: 26044383 DOI: 10.1016/j.chroma.2015.05.033] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Revised: 05/13/2015] [Accepted: 05/15/2015] [Indexed: 12/11/2022]
Abstract
The cytotoxic mechanism of many quinones has been correlated to covalent modification of cellular proteins. However, the identification of relevant proteins targets is essential but challenging goals. To better understand the quinones cytotoxic mechanism, human serum albumin (HSA) was incubated in vitro with different concentration of menadione (MQ). In this respect, the initial nucleophilic addition of proteins to quinone converts the conjugates to redox-cycling quinoproteins with altered conformation and secondary structure and extended life span than the short lived, free quinones. The conjugation of MQ with nucleophilic sites likewise, free cysteine as well as ɛ-amino group of lysine residue of HSA has been found to be in concentration dependent manner. The conventional methods for modified proteins identification in complex mixtures are complicated and time consuming. Herein, we describe a highly selective, sensitive, simple, and fast strategy for quinoproteins identification. The suggested strategy exploited the unique redox-cycling capability of quinoproteins in presence of a reductant, dithiothreitol (DTT), to generate reactive oxygen species (ROS) that gave sufficient chemiluminescence (CL) when mixed with luminol. The CL approach is highly selective and sensitive to detect the quinoproteins in ten-fold molar excess of native proteins without adduct enrichment. The approach was also coupled with gel filtration chromatography (GFC) and used to identify adducts in complex mixture of proteins in vitro as well as in rat plasma after MQ administration. Albumin was identified as the main protein in human and rat plasma forming adduct with MQ. Overall, the identification of quinoproteins will encourage further studies of toxicological impact of quinones on human health.
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Kültz D, Li J, Sacchi R, Morin D, Buckpitt A, Van Winkle L. Alterations in the proteome of the respiratory tract in response to single and multiple exposures to naphthalene. Proteomics 2015; 15:2655-68. [PMID: 25825134 DOI: 10.1002/pmic.201400445] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Revised: 01/16/2015] [Accepted: 03/25/2015] [Indexed: 12/12/2022]
Abstract
Protein adduction is considered to be critical to the loss of cellular homeostasis associated with environmental chemicals undergoing metabolic activation. Despite considerable effort, our understanding of the key proteins mediating the pathologic consequences from protein modification by electrophiles is incomplete. This work focused on naphthalene (NA) induced acute injury of respiratory epithelial cells and tolerance which arises after multiple toxicant doses to define the initial cellular proteomic response and later protective actions related to tolerance. Airways and nasal olfactory epithelium from mice exposed to 15 ppm NA either for 4 h (acute) or for 4 h/day × 7 days (tolerant) were used for label-free protein quantitation by LC/MS/MS. Cytochrome P450 2F2 and secretoglobin 1A1 are decreased dramatically in airways of mice exposed for 4 h, a finding consistent with the fact that CYPs are localized primarily in Clara cells. A number of heat shock proteins and protein disulfide isomerases, which had previously been identified as adduct targets for reactive metabolites from several lung toxicants, were upregulated in airways but not olfactory epithelium of tolerant mice. Protein targets that are upregulated in tolerance may be key players in the pathophysiology associated with reactive metabolite protein adduction. All MS data have been deposited in the ProteomeXchange with identifier PXD000846 (http://proteomecentral.proteomexchange.org/dataset/PXD000846).
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Affiliation(s)
- Dietmar Kültz
- Department of Animal Science, College of Agricultural and Environmental Sciences, University of California, Davis, CA, USA
| | - Johnathon Li
- Department of Animal Science, College of Agricultural and Environmental Sciences, University of California, Davis, CA, USA
| | - Romina Sacchi
- Department of Animal Science, College of Agricultural and Environmental Sciences, University of California, Davis, CA, USA
| | - Dexter Morin
- Depatment of Molecular Biosciences, University of California, Davis, CA, USA
| | - Alan Buckpitt
- Depatment of Molecular Biosciences, University of California, Davis, CA, USA
| | - Laura Van Winkle
- Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California, Davis, CA, USA
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Thorsell A, Isin EM, Jurva U. Use of Electrochemical Oxidation and Model Peptides To Study Nucleophilic Biological Targets of Reactive Metabolites: The Case of Rimonabant. Chem Res Toxicol 2014; 27:1808-20. [DOI: 10.1021/tx500255r] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Annika Thorsell
- DMPK Design and Biotransformation, CVMD iMed DMPK, AstraZeneca R&D Mölndal, Sweden, Pepparedsleden 1, SE-431 83, Mölndal, Sweden
| | - Emre M. Isin
- DMPK Design and Biotransformation, CVMD iMed DMPK, AstraZeneca R&D Mölndal, Sweden, Pepparedsleden 1, SE-431 83, Mölndal, Sweden
| | - Ulrik Jurva
- DMPK Design and Biotransformation, CVMD iMed DMPK, AstraZeneca R&D Mölndal, Sweden, Pepparedsleden 1, SE-431 83, Mölndal, Sweden
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Cichocki JA, Smith GJ, Mendoza R, Buckpitt AR, Van Winkle LS, Morris JB. Sex differences in the acute nasal antioxidant/antielectrophilic response of the rat to inhaled naphthalene. Toxicol Sci 2014; 139:234-44. [PMID: 24563378 DOI: 10.1093/toxsci/kfu031] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Naphthalene is a nasal carcinogen, inducing respiratory adenomas in male and olfactory neuroblastomas in female rats, respectively. The reasons for the site and sex-specific tumorigenic response are unknown. Naphthalene is bioactivated to electrophilic metabolites; cytotoxicity followed by regenerative cell proliferation is likely involved in the tumorigenic response. To examine sex differences in the acute nasal response to naphthalene, male and female F344 rats were nose-only exposed to 0, 1, 3, 10, or 30 ppm naphthalene vapor for 4 or 6 h. Following exposure, respiratory/transitional mucosa (RTM) and olfactory mucosa (OM) were isolated and analyzed for markers of oxidant/electrophilic stress and/or toxicity, including reduced/oxidized glutathione levels (GSH/GSSG), mRNA levels of electrophile-responsive genes, and epithelial cytoxicity (as measured by membrane permeability to ethidium homodimer-1). Naphthalene caused significant depletion of GSH in RTM and OM with no increase in GSSG. Cytotoxicity was apparent at concentrations of 15 and 30 ppm. No consistent sex differences were observed in these responses. Sex differences were observed in the induction of antielectrophilic genes in OM: glutamyl cysteine ligase (catalytic subunit) (Gclc), NADPH quinone oxidase 1 (Nqo1), and heme oxygenase 1 (Hmox1) were all induced to a greater extent in the male OM compared with the female. No consistent sex differences were observed in the RTM. Although the mechanism of the sex difference in the RTM adenoma response remains enigmatic, sex differences in the induction of antioxidant/electrophile-responsive genes may contribute to the heightened sensitivity of the female OM to the carcinogenic effects of naphthalene.
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Affiliation(s)
- Joseph A Cichocki
- University of Connecticut, Department of Pharmaceutical Sciences, Toxicology Program, Storrs, Connecticut, 06269
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