Abstract
A variety of polycyclic aromatic hydrocarbons and their dihydrodiol derivatives, arylamines, heterocyclic amines, and nitroarenes, were incubated with cDNA-based recombinant (Escherichia coli or Trichoplusia ni) systems expressing different forms of human cytochrome P450 (P450 or CYP) and NADPH-P450 reductase usingSalmonella typhimurium tester strain NM2009, and the resultant DNA damage caused by the reactive metabolites was detected by measuring expression of umu gene in the cells. Recombinant (bacterial) CYP1A1 was slightly more active than any of four CYP1B1 allelic variants, CYP1B1*1, CYP1B1*2, CYP1B1*3, and CYP1B1*6, in catalyzing activation of chrysene-1,2-diol, benz[a]anthracene-trans-1,2-, 3,4-, 5,6-, and 8,9-diol, fluoranthene-2,3-diol, dibenzo[a,l]pyrene, benzo[c]phenanthrene, and dibenz[a,h]anthracene and several arylamines and heterocyclic amines, whereas CYP1A1 and CYP1B1 enzymes had essentially similar catalytic specificities toward other procarcinogens, such as (+)-, (−)-, and (±)-benzo[a]pyrene-7,8-diol, 5-methylchrysene-1,2-diol, 7,12-dimethylbenz[a]anthracene-3,4-diol, dibenzo[a,l]pyrene-11,12-diol, benzo[b]fluoranthene-9,10-diol, benzo[c]chrysene, 5,6-dimethylchrysene-1,2-diol, benzo[c]phenanthrene-3,4-diol, 7,12-dimethylbenz[a]anthracene, benzo[a]pyrene, 5-methylchrysene, and benz[a]anthracene. We also determined activation of these procarcinogens by recombinant (T.ni) human P450 enzymes in S.typhimurium NM2009. There were good correlations between activities of procarcinogen activation by CYP1A1 preparations expressed in E. coli and T.ni cells, although basal activities with three lots of CYP1B1 in T. ni cells were very high without substrates and NADPH in our assay system. Using 14 forms of human P450s (but not CYP1B1) (in T. nicells), we found that CYP1A2, 2C9, 3A4, and 2C19 catalyzed activation of several of polycyclic aromatic hydrocarbons at much slower rates than those catalyzed by CYP1A1 and that other enzymes, including CYP2A6, 2B6, 2C8, 2C18, 2D6, 2E1, 3A5, 3A7, and 4A11, were almost inactive in the activation of polycyclic aromatic hydrocarbons examined here.
Footnotes
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This work was supported in part by grants from the Ministry of Education, Science, and Culture of Japan and the Ministry of Health and Welfare of Japan (T.S.); by United States Public Health Service Grants R35 CA44353 and P30 ES00267 (F.P.G.); and by the Kathleen Cuningham Foundation for Breast Cancer Research (E.M.J.G.).
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↵2 Nomenclature suggested by Oscarson et al. (http://www.imm.ki.se/CYPalleles).
- Abbreviations used are::
- PAH
- polycyclic aromatic hydrocarbon
- P450
- general term for cytochrome P450
- CYP
- individual forms of P450
- B[a]P
- benzo[a]pyrene
- 7,12-DMBA
- 7,12-dimethylbenz[a]anthracene
- DB[a,l]P
- dibenzo[a,l]pyrene
- MeIQ
- 2-amino-3,5-dimethylimidazo[4,5-f]quinoline
- Received March 26, 2001.
- Accepted May 15, 2001.
- The American Society for Pharmacology and Experimental Therapeutics
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