Abstract 3465: DNA adducts of tobacco-specific nitrosamines in human pancreatic tissue resulting from pyridylhydroxybutylation and pyridyloxobutylation

Abstract

Abstract Pancreatic cancer is the fourth leading cause of cancer-related deaths in the United States. Whereas cigarette smoking is a well established important risk factor for pancreatic cancer, the contribution of smokeless tobacco consumption is still a matter of debate. The tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is the only known compound present in tobacco and tobacco smoke which induces pancreatic tumors in animal models. In rats, the major NNK metabolite 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), proved to be an even more potent pancreatic carcinogen. NNK and NNAL have been detected in pancreatic juice. However, activation of NNK and NNAL leading to pyridyloxobutyl (POB) and pyridylhydroxybutyl (PHB) DNA adducts, respectively, has not been proven in human pancreas. Determination of POB DNA adducts was achieved by acid hydrolysis of 4-hydroxy-1-(3-pyridyl)-1-butanone (HPB) from DNA after addition of [3,3,4,4-D4]-HPB as internal standard, derivatization with pentafluorobenzoyl chloride (PFBC) and quantification by gas chromatography/high resolution mass spectrometry with negative chemical ionization according to Heppel et al. (Anal Bioanal Chem 393:1525-30, 2009). POB DNA adducts could be easily detected in 8 of 11 pancreatic samples of sudden death victims from Germany at 2.95±1.08 fmol/µg DNA (mean±standard error; values below detection limit set at zero). Using [3,3,4,4-D4]-diol as internal standard, this analytical method also revealed the presence of PHB adducts in pancreatic DNA releasing 4-hydroxy-1-(3-pyridyl)-1-butanol (diol). However, because of massive peak broadening the PFBC ester of diol could not be quantified reliably. To improve the chromatographic resolution, the PFBC ester of diol was further derivatized according to Kao and Giese (Chem Res Toxicol 18:70-5, 2005) with pivalic anhydride to cap the secondary hydroxy group. The resulting tert-butyl esters of the PFBC esters of diol and [3,3,4,4-D4]-diol show excellent performance in capillary gas chromatography and allow quantification by single ion monitoring at the molecular masses of m/z 445.13 and m/z 449.16, respectively. In summary, the presence of POB and PHB DNA adducts in human pancreatic tissue has been clearly demonstrated for the first time. Further studies will show the specificity of these pancreatic DNA adducts for smoking and smokeless tobacco consumption and the correlation with other tobacco-specific biomarkers. Supported by a grant of the Institute for Science and Health, St. Louis, MO. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3465.