The objectives of this biochemical research are to explore the role and regulation of bioalkylation in the activation of PAHs in chemical carcinogenesis. The bioalkylation substitution reaction of PAHs, consists of a biochemical reaction between certain unsubstituted PAHs and S-adenosyl-L-methionine (SAM) that is catalyzed by cytosolic enzymes. The introduction of the alkyl group takes place in the reactive meso-anthracenic positions or L- region. The rate and extent of the bioalkylation reaction of anthracene, benz(a)anthrcene, benzo(a)pyrene, anthanthrene and pyrene will be measured in cytosol preparations of rat liver, lung and subcutaneous tissue. Although some evidence for bioalkylation of PAHs in vivo has already been obtained, it is obviously desirable to quantitate both the rate and extent of this new biochemical reaction with SAM and without added SAM for comparison with in vitro studies. In contrast to most studies in this field this alternative pathway of activation by soluble enzymes does not involve microsomal reactions but is entirely concerned with the biochemical reactions that occur in cytosol preparations that are essentially free of microsomes. An intimately associated biological oxidation of the hydrocarbon also occurs in cytosol preparations and studies that are designed to determine the mechanism of the oxidation will also be undertaken in collaboration with Dr. Lauren Tolbert. The biosynthetic products of these cytosolic reactions will be identified by HPLC and GC/MS in most cases by comparison with authentic reference compounds. Carcinogenic activity will be determined in rats by subcutaneous injection of the PAH with and without other compounds that may enhance or inhibit carcinogenic activity. The isolation and characterization of specific end products of reaction of the cytosolic metabolites and model ultimate metabolites with macromolecules in vivo will be explored.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA045823-02
Application #
3189118
Study Section
Metabolic Pathology Study Section (MEP)
Project Start
1987-09-30
Project End
1990-08-31
Budget Start
1988-09-01
Budget End
1989-08-31
Support Year
2
Fiscal Year
1988
Total Cost
Indirect Cost
Name
University of Kentucky
Department
Type
Schools of Medicine
DUNS #
832127323
City
Lexington
State
KY
Country
United States
Zip Code
40506
Flesher, J W; Horn, J; Lehner, A F (1998) Carcinogenicity of 1-hydroxy-3-methylcholanthrene and its electrophilic sulfate ester 1-sulfooxy-3-methylcholanthrene in Sprague-Dawley rats. Biochem Biophys Res Commun 243:30-5
Flesher, J W; Horn, J; Lehner, A F (1997) 7-Sulfooxymethyl-12-methylbenz[a]anthracene is an exceptionally reactive electrophilic mutagen and ultimate carcinogen. Biochem Biophys Res Commun 231:144-8
Flesher, J W; Horn, J; Lehner, A F (1997) 6-sulfooxymethylbenzo[a]pyrene is an ultimate electrophilic and carcinogenic form of the intermediary metabolite 6-hydroxymethylbenzo[a]pyrene. Biochem Biophys Res Commun 234:554-8
Flesher, J W; Horn, J; Lehner, A F (1997) 7-Sulfooxymethylbenz[a]anthracene is an ultimate electrophilic and carcinogenic form of 7-hydroxymethylbenz[a]anthracene. Biochem Biophys Res Commun 231:712-6
Horn, J; Flesher, J W; Lehner, A F (1996) 1-Sulfooxymethylpyrene is an electrophilic mutagen and ultimate carcinogen of 1-methyl- and 1-hydroxymethylpyrene. Biochem Biophys Res Commun 228:105-9
Stansbury, K H; Flesher, J W; Gupta, R C (1994) Mechanism of aralkyl-DNA adduct formation from benzo[a]pyrene in vivo. Chem Res Toxicol 7:254-9
Myers, S R; Flesher, J W (1991) Metabolism of chrysene, 5-methylchrysene, 6-methylchrysene and 5,6-dimethylchrysene in rat liver cytosol, in vitro, and in rat subcutaneous tissue, in vivo. Chem Biol Interact 77:203-21
Flesher, J W; Myers, S R (1991) Methyl-substitution of benzene and toluene in preparations of human bone marrow. Life Sci 48:843-50
Flesher, J W; Myers, S R (1991) Rules of molecular geometry for predicting carcinogenic activity of unsubstituted polynuclear aromatic hydrocarbons. Teratog Carcinog Mutagen 11:41-54
Myers, S R; Flesher, J W (1991) Bioalkylation of benz[a]anthracene, 7-methylbenz[a]anthracene, and 12-methylbenz[a]anthracene in rat lung cytosol preparations. Biochem Pharmacol 41:1683-9

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