Quantification of benzo[a]pyrene diol epoxide DNA-adducts by stable isotope dilution liquid chromatography/tandem mass spectrometry.
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants found in car exhausts, charbroiled food, and tobacco smoke. Three pathways for the metabolic activation of B[a]P to ultimate carcinogens have been proposed. The most widely accepted pathway involves cytochrome-P450 (CYP) 1A1- and/or 1B1-mediated formation of B[a]P-7,8-oxide, which undergoes epoxide hydrolase-mediated metabolism to the proximate carcinogen B[a]P-7,8-dihydro-7,8-diol. Further CYP1A1- and/or CYP1B1-mediated activation of the dihydrodiol results in the formation of 7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (B[a]PDE), the ultimate carcinogen. In previous studies, it was demonstrated that (+)-anti-B[a]PDE was the most potent tumorigen of the CYP-derived B[a]PDE diastereomers. We have developed a stable isotope dilution, liquid chromatography multiple reaction monitoring/mass spectrometry (LC-MRM/MS) assay for all eight (+/-)-anti-B[a]PDE-derived dGuo and dAdo DNA-adducts. The LC-MRM/MS assay was rigorously validated and used to show that (+)-anti-trans-B[a]PDE-dGuo was the major adduct formed when naked DNA and human bronchoalveolar adenocarcinoma H358 cells were treated with (+/-)-anti-B[a]PDE. The preference for DNA-adducts derived from (+)-anti-B[a]PDE was even more apparent in cellular DNA. Thus, the increased potency of (+)-anti-B[a]PDE as a tumorigen is most likely due its ability to preferentially form DNA-adducts when compared with (-)-anti-B[a]PDE. Also, the adduct profile suggests that this occurs by binding of (+)-anti-B[a]PDE to DNA in a manner that facilitates covalent binding to dGuo rather than dAdo residues.
Center for Cancer Pharmacology, University of Pennsylvania School of Medicine, 854 BRB II/III, 421 Curie Boulevard, Philadelphia, PA 19104-6160, USA.
Qian
Q
Ruan
Hye-Young H
HY
Kim
Hao
H
Jiang
Trevor M
TM
Penning
Ronald G
RG
Harvey
Ian A
IA
Blair
D000241:Adenosine / Q000737:chemistry; D000818:Animals; D001580:Benzopyrenes / Q000138:chemical synthesis / Q000737:chemistry*; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D002138:Calibration; D002417:Cattle; D045744:Cell Line, Tumor; D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D018736:DNA Adducts / Q000032:analysis*; D006151:Guanosine / Q000737:chemistry; D006801:Humans; D006868:Hydrolysis; D008968:Molecular Conformation; D011786:Quality Control; D015203:Reproducibility of Results; D053719:Tandem Mass Spectrometry; D013950:Thymus Gland / Q000737:chemistry
D001580:Benzopyrenes; D018736:DNA Adducts; D006151:Guanosine; C072019:benzo(a)pyrene diolepoxide I; D000241:Adenosine