Analysis of r-7,t-8,9,c-10-tetrahydroxy-7,8,9,10-tetrahydrobenzo[a]pyrene in human urine: a biomarker for directly assessing carcinogenic polycyclic aromatic hydrocarbon exposure plus metabolic activation.
Polycyclic aromatic hydrocarbons (PAH) are believed to be causative agents for various types of cancers in humans. Benzo[a]pyrene (BaP) is a prototypic carcinogenic PAH, which requires metabolic activation to elicit its detrimental effects. The major end product of its diol epoxide metabolic activation pathway is r-7,t-8,9,c-10-tetrahydroxy-7,8,9,10-tetrahydrobenzo[a]pyrene (trans, anti-BaPT). Individual differences in exposure to, and metabolic activation of, carcinogenic PAH may influence cancer risk. Measurement of PAH metabolites in human urine could provide a direct way to assess individual differences in susceptibility to PAH-related cancer. In this article, we describe a sensitive and reliable method for the quantitation of trans, anti-BaPT in human urine using gas chromatography-negative ion chemical ionization-tandem mass spectrometry (GC-NICI-MS/MS). [(13)C(6)] trans, anti-BaPT was used as the internal standard. The urine was treated with β-glucuronidase and sulfatase, and then trans, anti-BaPT was enriched by solid-phase extraction with polymeric reversed phase and phenylboronic acid cartridges. The sample was silylated and analyzed by GC-NICI-MS/MS with selected reaction monitoring (SRM) for the trimethylsilyl (TMS) derivatives of trans, anti-BaPT (m/z 446 → m/z 255) and [(13)C(6)]trans, anti-BaPT (m/z 452 → m/z 261). The mean assay recovery was 44%. The instrumental on-column detection limit was about 20 amol of trans, anti-BaPT (as BaPT-TMS). trans, anti-BaPT was readily detected in all urine samples analyzed including those of 30 smokers (0.71 ± 0.64 fmol/mg creatinine) and 30 nonsmokers (0.34 ± 0.2 fmol/mg creatinine) (P = 0.0036). The results of this study demonstrate a highly sensitive and selective method for the quantitation of trans, anti-BaPT in human urine. This is to our knowledge the first study to show that smokers have significantly higher levels of trans, anti-BaPT in their urine than do nonsmokers. This method may be useful as a direct phenotyping approach to assess individual differences in uptake and metabolic activation of carcinogenic PAH.
Masonic Cancer Center and Department of Pharmacology, University of Minnesota, Minneapolis, Minnesota 55455, USA.
Yan
Y
Zhong
Steven G
SG
Carmella
J Bradley
JB
Hochalter
Silvia
S
Balbo
Stephen S
SS
Hecht
D000328:Adult; D015415:Biomarkers / Q000652:urine; D002273:Carcinogens / Q000737:chemistry* / Q000633:toxicity; D002478:Cells, Cultured; D003404:Creatinine / Q000737:chemistry; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D005966:Glucuronidase / Q000378:metabolism; D006801:Humans; D007536:Isomerism; D008297:Male; D008875:Middle Aged; D011084:Polycyclic Aromatic Hydrocarbons / Q000737:chemistry* / Q000633:toxicity; D011721:Pyrenes / Q000737:chemistry*; D012907:Smoking / Q000652:urine; D052616:Solid Phase Extraction; D013429:Sulfatases / Q000378:metabolism
D015415:Biomarkers; D002273:Carcinogens; D011084:Polycyclic Aromatic Hydrocarbons; D011721:Pyrenes; C557967:r-7,t-8,9,c-10-tetrahydroxy-7,8,9,10-tetrahydrobenzo(a)pyrene; D003404:Creatinine; D013429:Sulfatases; D005966:Glucuronidase