Multi-Class Carcinogenic DNA Adduct Quantification in Formalin-Fixed Paraffin-Embedded Tissues by Ultra-Performance Liquid Chromatography–Tandem Mass Spectrometry

摘要

DNA adducts are a measure of internal exposure to genotoxicants and an important biomarker for human risk assessment. However, the employment of DNA adducts as biomarkers in human studies is often restricted because fresh frozen tissues are not available. In contrast, formalin-fixed paraffin embedded (FFPE) tissues with clinical diagnosis are readily accessible. Recently, our laboratory reported that DNA adducts of aristolochic acid, a carcinogenic component of Aristolochia herbs used in traditional Chinese medicines world-wide, can be recovered quantitatively from FFPE tissues. In this study, we have evaluated the efficacy of our method for retrieval of DNA adducts from archived tissue by measuring DNA adducts derived from four other classes of human carcinogens: polycyclic aromatic hydrocarbons (PAHs), aromatic amines, heterocyclic aromatic amines (HAAs), and N-nitroso compounds (NOCs). The deoxyguanosine (dG) adducts of the PAH benzo[a]pyrene (B[a]P), 10-(deoxyguanosin-N²-yl)-7,8,9-trihydroxy-7,8,9,10-tetrahydro-benzo[a]pyrene (dG-N²-B[a]PDE); the aromatic amine 4-aminobiphenyl (4-ABP), N-(deoxyguanosin-8-yl)-4-ABP (dG-C8-4-ABP); the HAA 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), N-(deoxyguanosin-8-yl)-PhIP (dG-C8-PhIP); and the dG adducts of the NOC, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), O⁶-methyl-dG (O⁶-Me-dG) and O⁶-pyridyloxobutyl-dG (O⁶-POB-dG) formed in liver, lung, bladder, pancreas, or colon were recovered in comparable yields from fresh frozen and FFPE preserved tissues of rodents treated with the procarcinogens. Quantification was achieved by Ultra-Performance Liquid Chromatography-Electrospray Ionization-Ion Trap-Multistage Mass Spectrometry (UPLC-ESI-IT-MS³). These advancements in the technology of DNA adduct retrieval from FFPE tissue clear the way for the use of archived pathology samples in molecular epidemiology studies designed to assess the causal role of exposures to hazardous chemicals with cancer risk.