title: Aldo-keto reductase- and cytochrome P450-dependent formation of benzo[a]pyrene-derived DNA adducts in human bronchoalveolar cells.
abstract: There is substantial evidence to suggest that polycyclic aromatic hydrocarbons (PAHs) such as benzo[a]pyrene (B[a]P) induce lung cancer through metabolic activation. As part of a program to delineate the routes of PAH activation, we have examined DNA adducts that are formed in human lung cells. A stable isotope dilution liquid chromatography/multiple reaction monitoring mass spectrometry method was used to quantify eight anti-7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydro-B[a]P (B[a]PDE)-derived DNA adducts in four H358 human bronchoalveolar cell lines with different phenotypes. In P450 1A1/P450 1B1-induced H358 cells exposed to (+/-)-B[a]P-7,8-dihydro-7,8-diol (B[a]P-7,8-dihydrodiol), (+)-anti-trans-B[a]PDE-N2-2'-deoxyguanosine [(+)-anti-trans-B[a]PDE-N2-dGuo] was the major DNA adduct, and it formed with no lag phase. In AKR1A1-transfected H358 cells, (+)-anti-trans-B[a]PDE-N2-dGuo was also the major adduct with a 3 h lag phase before significant adduct formation was detected. In AKR1A1-transfected H358 cells with induced P450 1A1/P450 1B1, (+)-anti-trans-B[a]PDE-N2-dGuo was formed with no lag phase in amounts similar to those in the H358 cells with up-regulated P450 1A1/P450 1B1. Surprisingly, the greatest amount of (+)-anti-trans-B[a]PDE-N2-dGuo was formed in the control H358 cells. Furthermore, (+)-anti-trans-B[a]PDE-N2-dGuo formation was 2-fold higher in (-)-B[a]P-7,8-dihydrodiol-exposed H358 cells when compared with (+/-)-B[a]P-7,8-dihydrodiol-exposed cells. The P450 1A1/1B1 inhibitor 2,4,3',5'-tetramethoxystilbene did not attenuate DNA adduct formation in the control H358 cells, suggesting that another P450 was responsible. These data raise the intriguing possibility that P450 1A1/P450 1B1 and AKR1A1 may be protective against (+)-B[a]PDE-mediated DNA damage.
authors.affiliation: Centers for Cancer Pharmacology and Excellence in Environmental Toxicology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6160, USA.
authors.forename: Qian
authors.initials: Q
authors.lastname: Ruan
authors.forename: Stacy L
authors.initials: SL
authors.lastname: Gelhaus
authors.forename: Trevor M
authors.initials: TM
authors.lastname: Penning
authors.forename: Ronald G
authors.initials: RG
authors.lastname: Harvey
authors.forename: Ian A
authors.initials: IA
authors.lastname: Blair
mesh_terms: D000429:Alcohol Oxidoreductases / Q000378:metabolism*; D000449:Aldehyde Reductase / Q000378:metabolism*; D001564:Benzo(a)pyrene / Q000378:metabolism* / Q000633:toxicity*; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology*; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D018736:DNA Adducts / Q000187:drug effects* / Q000302:isolation & purification; D006801:Humans; D006868:Hydrolysis; D000072317:Polychlorinated Dibenzodioxins / Q000633:toxicity; D013056:Spectrophotometry, Ultraviolet; D013237:Stereoisomerism; D013723:Teratogens / Q000633:toxicity; D014162:Transfection
chemical_list: D018736:DNA Adducts; D000072317:Polychlorinated Dibenzodioxins; D013723:Teratogens; D001564:Benzo(a)pyrene; D003577:Cytochrome P-450 Enzyme System; D000429:Alcohol Oxidoreductases; D000449:Aldehyde Reductase