Abstract 1694: Selective formation of the γ isomer of 1,N2-propanodeoxyguanosine adducts of acrolein through interactions with amine-containing molecules

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Abstract Acrolein (Acr) is a highly reactive α,β-unsaturated aldehyde found ubiquitously in the environment and also formed endogenously as a major product from oxidation of polyunsaturated fatty acids. Acr can bind to deoxyguanosine (dG) to form two regioisomers of 1,N2-propanodeoxyguanosine adducts (α- or γ-Acr-dG depending on the position of the OH group). However, in most cases γ-Acr-dG is the major adduct detected in rodent and human tissues and Acr-treated cells. Our LC-MS/MS analyses of seven human lung and liver tissues confirmed previous findings that γ-Acr-dG is the major isomer. The reasons for the apparent prevalence of γ-Acr-dG in vivo are unclear. To determine whether the reaction of Acr with cellular molecules alter isomer formation, the soluble fraction of BEAS-2B cell lysate was reacted with equimolar concentrations of Acr and dG in 100 mM sodium phosphate buffer (pH 7.4) at 37° C for 24 h. Acr-dG was detected and quantified via HPLC-UV. In reactions without cell lysate, α- and γ-Acr-dG were detected in approximately equivalent amounts; however, in the presence of cell lysate the amount of α-Acr-dG decreased compared to γ-Acr-dG in a concentration-dependent manner. Similar results were obtained in the reactions with amino acids, histones, and polyamines under the same conditions or with a Tris buffer instead of a phosphate buffer. Additionally, LC-MS/MS analysis of reactions of these compounds with calf thymus DNA rather than dG yielded similar results. These results suggest that amino compounds are needed for the selective formation of the γ isomer. To investigate the intermediate(s) involved, Acr was reacted with arginine in 100 mM sodium phosphate buffer (pH 7.4). Analyses by HPLC-UV show that an initial compound forms quickly, but decomposes over time to give rise to a stable compound. These compounds were collected separately and reacted with dG. While Acr-dG was not detected in reactions with the stable compound, the initial compound predominately gave rise to γ-Acr-dG. It is likely that a similar or related unstable intermediate formed between Acr and an amine-containing molecule is responsible for the formation of DNA adducts in vivo. (Supported by NCI grant CA043159.) 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 1694.