Abstract 4639: Effects of defined amounts of alcohol consumption on levels of N2-ethylidene-dGuo in DNA from human buccal cells and peripheral blood nucleated cells

Acetaldehyde, the primary metabolite of ethanol, is implicated in the carcinogenic effect of alcohol. This oxidized metabolite of ethanol reacts with DNA bases forming adducts, which play a key role in chemically induced carcinogenesis. N2-Ethylidenedeoxyguanosine (N2-Eti-dGuo) is the major adduct formed by this reaction. Several studies have shown an association between alcohol drinking and levels of this DNA adduct, suggesting its potential use as biomarker for the study of alcohol related carcinogenesis. However, there are no reports on the kinetics of formation and repair of N2-Eti-dGuo after alcohol consumption. Formation and lifetime of DNA adducts in humans is not always clear and can vary according to tissue or cell type. Therefore we investigated levels of N2-Eti-dGuo in DNA from peripheral blood monocytes, granulocytes, and buccal cells at several time points after consumption of different doses of alcohol. We recruited ten non-smokers, who regularly consume alcohol in moderation but with no history of alcohol abuse. Subjects participated to three drinking sessions targeting increasing blood alcohol levels: 0.03%, 0.05%, and 0.07%. Participants refrained from drinking for the duration of the study except for the administered alcohol dose. Mouthwash and blood samples were taken 1 h before the dose and 2, 4, 6, 24 h and 2, 5 and 7 days after. Blood samples were immediately processed to isolate granulocytes and monocytes using a Ficoll gradient. Efficiency of the cell separation was confirmed by flow-cytometry. DNA was extracted from these cells and from the buccal cells collected with the mouthwash. N2-Eti-dGuo was measured by LC-ESI-MS/MS. Preliminary results from the samples from the highest dose tested showed an average ten-fold increase of levels of N2-Eti-dGuo in buccal cell DNA 2 and 4 h after exposure, the levels of the adduct decreased after 24 h but showed a new two-fold increase, between 2 and 5 days from exposure. Levels of N2-Eti-dGuo in monocytes and granulocytes DNA did not increase within 6 h from the dose but only after 24 h from exposure. The results obtained from the granulocytes’ DNA showed an average three-fold increase after 24 h reaching a peak 2 or 5 days after the dose. The results obtained from the monocytes followed a similar trend but showed an average two-fold increase 24 h or 2 days after the dose. These results indicate a clear effect of alcohol on buccal cell DNA within 6 h after exposure and an unexpected increase of N2-Eti-dGuo beginning 24 h after alcohol consumption in monocytes and granulocytes. These unexpected results underline the importance of selecting the right surrogate tissue and time-point for the analysis of effects of alcohol on N2-Eti-dGuo and thus for further investigation of the use of this DNA adduct as a biomarker. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4639. doi:10.1158/1538-7445.AM2011-4639