Effects of smoking, alcohol abusus and chronic reflux on 4-hydroxy-1-(3-pyridyl)-1-butanone-releasing DNA adducts in the lower esophagus

1884 4-Hydroxy-1-(3-pyridyl)-1-butanone (HPB)-releasing DNA adducts derived from metabolic activation of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and N’-nitrosonornico¬tine (NNN) have been proposed as specific biomarkers of exposure to tobacco products and tobacco smoke. These adducts have been implicated in lung carcinogenesis by NNK and esophageal tumors by NNN. HPB-releasing adducts are also formed by nitrosation and peroxidation from the minor tobacco alkaloid myosmine. Because of its wide spread occurrence in human diet, myosmine is not tobacco-specific. Myosmine is secreted into the stomach and with saliva and is supposed to lead to the formation of DNA adducts under the nitrosative conditions within the gastroesophageal junction. In the course of endoscopy on patients with different stages of esophageal carcinoma, biopsies were obtained from 82 patients (39 males, 43 females, 53 nonsmokers, 29 smokers) for the determination of HPB-releasing adducts. Additionally, plasma were taken for analysis of cotinine and myosmine. The patients filled in a questionnaire on smoking, frequency of alcohol drinking and dietary habits as well as medical treatments and signs of reflux. HPB-releasing adducts were determined after acid hydrolysis of DNA and derivatisation by high resolution gas chromatography/mass spectrometry with negative chemical ionization. The method has a limit of detection of 92 fmol/mg DNA and a corresponding limit of quantification of 277 fmol/mg DNA. The average adduct levels in esophageal biopsies of 82 patients was 5037 ± 8333 fmol HPB/mg DNA with no dependency on age and gender. Whereas the differences between smokers and nonsmokers did not reach significance (n = 29, 4742±8967 versus n = 53, 5198±8049; n.s.), frequent drinkers of alcoholic beverages showed significantly higher adduct levels (n = 20, 9946±13341 fmol/pg DNA) compared to infrequent drinkers (n = 54, 3700±5405 fmol/mg DNA; p