CYP2S1 is a recently identified human cytochrome P450, expressed extensively in epithelial tissues. We propose that CYP2S1 plays a significant role in the metabolic activation of environmental procarcinogens, and the metabolism of pharmaceuticals and endogenous compounds. The proposal will address this hypothesis and characterize regulation of the enzyme. There are three specific aims: (i) We have expressed human CYP2S1 in bacteria, and demonstrated that it metabolizes several compounds that are toxic and/or carcinogenic to epithelial tissues. We will also over-express the enzyme in mammalian cells. Using these expression systems, we will screen for additional substrates, and also for procarcinogens that are activated to mutagenic (and therefore probably carcinogenic) derivatives by CYP2S1. The Km and Vmax values will be determined for representative compounds, and the metabolites that are formed will be identified. The degree to which CYP2S1 contributes towards the total metabolism of particular substrates in human epithelial tissues will be determined using an inhibitory antibody to the enzyme, (ii) We have shown that CYP2S1 is inducible by dioxin, carcinogenic polycyclic aromatic hydrocarbons (PAHs), and hypoxia. We will investigate whether the potential Xenobiotic Responsive Elements (XREs), or the potential Antioxidant Response Element (ARE) in the 5' flanking region of the human CYP2S1 gene mediate induction by dioxin and/or PAHs, and address the hypothesis that due to the particular nucleotide sequences of the above XREs, the gene responds better to PAHs than to dioxin in certain cells. We will also analyze the mechanism of hypoxic induction of the gene, (iii) We will generate a knockout mouse for Cyp2s1, and then generate a derivative of this mouse containing the human CYP2S1 gene, including its flanking regulatory regions. This """"""""CYP2S1-humanized"""""""" mouse will be used to study the metabolism of substrates of human CYP2S1, the biological consequences of this metabolism, and the regulation of the human CYP2S1 gene by xenobiotics and hypoxia, thus complementing and extending specific aims 1 and 2. Our studies may demonstrate important roles for CYP2S1 in the metabolism of carcinogens, Pharmaceuticals and endogenous compounds, and may ultimately provide opportunities for reducing the deleterious effects of environmental carcinogens and the adverse effects of certain Pharmaceuticals in the human population. ? ? ? ?

Agency
National Institute of Health (NIH)
Institute
National Institute of Environmental Health Sciences (NIEHS)
Type
Research Project (R01)
Project #
5R01ES015384-03
Application #
7476561
Study Section
Xenobiotic and Nutrient Disposition and Action Study Section (XNDA)
Program Officer
Thompson, Claudia L
Project Start
2006-09-28
Project End
2011-07-31
Budget Start
2008-08-01
Budget End
2009-07-31
Support Year
3
Fiscal Year
2008
Total Cost
$244,419
Indirect Cost
Name
University of California Los Angeles
Department
Pathology
Type
Schools of Medicine
DUNS #
092530369
City
Los Angeles
State
CA
Country
United States
Zip Code
90095
Solaimani, Parrisa; Wang, Feng; Hankinson, Oliver (2014) SIN3A, generally regarded as a transcriptional repressor, is required for induction of gene transcription by the aryl hydrocarbon receptor. J Biol Chem 289:33655-62
Ingelman-Sundberg, Magnus; Zhong, Xiao-Bo; Hankinson, Oliver et al. (2013) Potential role of epigenetic mechanisms in the regulation of drug metabolism and transport. Drug Metab Dispos 41:1725-31
Yang, Jun; Solaimani, Parrisa; Dong, Hua et al. (2013) Treatment of mice with 2,3,7,8-Tetrachlorodibenzo-p-dioxin markedly increases the levels of a number of cytochrome P450 metabolites of omega-3 polyunsaturated fatty acids in the liver and lung. J Toxicol Sci 38:833-6
Solaimani, Parrisa; Damoiseaux, Robert; Hankinson, Oliver (2013) Genome-wide RNAi high-throughput screen identifies proteins necessary for the AHR-dependent induction of CYP1A1 by 2,3,7,8-tetrachlorodibenzo-p-dioxin. Toxicol Sci 136:107-19
Bebenek, Ilona G; Solaimani, Parrisa; Bui, Peter et al. (2012) CYP2S1 is negatively regulated by corticosteroids in human cell lines. Toxicol Lett 209:30-4
Bui, Peter; Solaimani, Parrisa; Wu, Xiaomeng et al. (2012) 2,3,7,8-Tetrachlorodibenzo-p-dioxin treatment alters eicosanoid levels in several organs of the mouse in an aryl hydrocarbon receptor-dependent fashion. Toxicol Appl Pharmacol 259:143-51
Bui, Peter; Imaizumi, Satoshi; Beedanagari, Sudheer Reddy et al. (2011) Human CYP2S1 metabolizes cyclooxygenase- and lipoxygenase-derived eicosanoids. Drug Metab Dispos 39:180-90
Quesada, Arnulfo; Bui, Peter H; Homanics, Gregg E et al. (2011) Comparison of mibefradil and derivative NNC 55-0396 effects on behavior, cytochrome P450 activity, and tremor in mouse models of essential tremor. Eur J Pharmacol 659:30-6
Bui, Peter H; Hankinson, Oliver (2009) Functional characterization of human cytochrome P450 2S1 using a synthetic gene-expressed protein in Escherichia coli. Mol Pharmacol 76:1031-43
Bui, Peter H; Hsu, Erin L; Hankinson, Oliver (2009) Fatty acid hydroperoxides support cytochrome P450 2S1-mediated bioactivation of benzo[a]pyrene-7,8-dihydrodiol. Mol Pharmacol 76:1044-52

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