Premium
A quantitative comparison of dibenzo[ a,l ]pyrene‐DNA adduct formation by recombinant human cytochrome P450 microsomes
Author(s) -
King Leon C.,
Adams Linda,
Allison Joycelyn,
Kohan Michael J.,
Nelson Garret,
Desai Dhimant,
Amin Shantu,
Ross Jeffrey A.
Publication year - 1999
Publication title -
molecular carcinogenesis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.254
H-Index - 97
eISSN - 1098-2744
pISSN - 0899-1987
DOI - 10.1002/(sici)1098-2744(199910)26:2<74::aid-mc2>3.0.co;2-9
Subject(s) - cytochrome p450 , adduct , microsome , biology , pyrene , carcinogen , dna , diol , metabolite , epoxide , recombinant dna , benzo(a)pyrene , enzyme , stereochemistry , biochemistry , chemistry , gene , catalysis , organic chemistry , astrobiology
Dibenzo[ a,l ]pyrene (DB[ a,l ]P), an extremely potent environmental carcinogen, is metabolically activated in mammalian cells and microsomes through the fjord‐region dihydrodiol, trans ‐DB[ a,l ]P‐11,12‐diol, to syn ‐ and anti ‐DB[ a,l ]P‐11,12‐diol‐13,14‐epoxides ( syn ‐ and anti ‐DB[ a,l ]PDEs). The role of seven individual recombinant human cytochrome P450s (1A1, 1A2, 1B1, 2B6, 2C9, 2E1, and 3A4) in the metabolic activation of DB[ a,l ]P and formation of DNA adducts was examined by using 32 P postlabeling, thin‐layer chromatography, and high‐pressure liquid chromatography. We found that, in the presence of epoxide hydrolase, only P450 1A1 and P450 1B1 catalyzed the formation of DB[ a,l ]PDE‐DNA adducts and several unidentified polar adducts. Human P450 1A1 catalyzed the formation of DB[ a,l ]PDE‐DNA adducts and unidentified polar adducts at rates threefold and 17‐fold greater than did human P450 1B1 (256 fmol/h/nmol P450 versus 90 fmol/h/nmol P450 and 132 fmol/h/nmol P450 versus 8 fmol/h/nmol P450, respectively). P450 1A1 DNA adducts were derived from both anti ‐ and syn ‐DB[ a,l ]PDE at rates of 73 fmol/h/nmol P450 and 51 fmol/h/nmol P450, respectively. P450 1B1 produced adducts derived from anti ‐DB[ a,l ]PDE at a rate of 82 fmol/h/nmol, whereas only a small number of adducts were derived from syn ‐DB[ a,l ]PDE (0.4 fmol/h/nmol). These results demonstrated the potential of human P450 1A1 and P450 1B1 to contribute to the metabolic activation and carcinogenicity of DB[ a,l ]P and provided additional evidence that human P450 1A1 and 1B1 differ in their stereospecific activation of DB[ a,l ]P. Mol. Carcinog. 26:74–82, 1999. Published 1999 Wiley‐Liss, Inc.