Detection and Quantification of Depurinated Benzo[a]pyrene-Adducted DNA Bases in the Urine of Cigarette Smokers and Women Exposed to Household Coal Smoke

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• 作者：George P. Casale ; Maria Singhal ; Sumitra Bhattacharya ; Regulan RamaNathan ; Kenneth P. Roberts ; Damon C. Barbacci ; John Zhao ; Ryszard Jankowiak ; Michael L. Gross ; Ercole L. Cavalieri ; Gerald J. Small
• 刊名：Chemical Research in Toxicology
• 出版年：2001
• 出版时间：February 2001
• 年：2001
• 卷：14
• 期：2
• 页码：192 - 201
• 全文大小：125K
• 年卷期：v.14,no.2(February 2001)
• ISSN：1520-5010

文摘

Polycyclic aromatic hydrocarbons (PAH) are metabolized to electrophiles that can bind toDNA bases and destabilize the N-glycosyl bond, causing rapid depurination of the adductedbases. Recent studies support depurination of DNA as a mechanism central to the genesis ofH-ras mutations in PAH-treated mouse skin. Depurinating adducts account for 71% of all DNAadducts formed in mouse skin treated with benzo[a]pyrene (BP). This study analyzed urine ofcigarette smokers, coal smoke-exposed women, and nonexposed controls for the presence andquantities of the depurinated BP-adducted DNA bases, 7-(benzo[a]pyren-6-yl)guanine (BP-6-N7Gua) and 7-(benzo[a]pyren-6-yl)adenine (BP-6-N7Ade). Since these adducted bases originatefrom reaction of the BP radical cation with double-stranded DNA and not with RNA ordenatured DNA, their presence in urine is indicative of DNA damage. Urine samples werefractionated by a combination of SepPak extraction and reverse-phase HPLC, and then analyzedby tandem mass spectrometry and capillary electrophoresis with laser-induced fluorescence.BP-adducted bases were detected in the urine from three of seven cigarette smokers and threeof seven women exposed to coal smoke, but were not detected in urine from the 13 controlsubjects. Concentrations were estimated to be 60-340 and 0.1-0.6 fmol/mg of creatinineequivalent of urine for coal smoke-exposed women (maximum possible BP intake of ca. 23 000ng/day) and cigarette smokers (BP intake of ca. 800 ng/day), respectively, exhibiting a sensitiveresponse to BP exposures. BP-6-N7Gua was present at ca. 20-300 times the concentration ofBP-6-N7Ade in the urine of coal smoke-exposed women, but was not detected in the urine ofcigarette smokers. This difference may be due to the remarkably different BP exposuresexperienced by the two groups of PAH-exposed individuals. These results justify more extensivestudies of depurinated BP-adducted DNA bases as potential biomarkers of PAH-associatedcancer risk.