Abstract 3602: Effect of alcohol on DB[a,l]P, an environmental pollutant and a tobacco smoke constituent, on DNA adduct formation in mouse oral tissues.

Abstract

Abstract Alcohol acts synergistically with tobacco smoke to greatly increase the risk of oral squamous cell carcinoma (OSCC) up to 20-fold; the mechanisms of this synergism remain unknown. Research in this area has been hampered by the lack of appropriate animal models that would mimic chronic simultaneous human exposure to alcohol and representative carcinogens in tobacco or tobacco smoke as a whole. Recently, we developed a more relevant animal model (Int. J. Cancer, 2012, 2783-90) and showed that dibenzo[a,l]pyrene (DB[a,l]P), an environmental pollutant and a tobacco smoke component, induces SCC in oral tissues of mice. We also showed that its diol epoxide metabolite, (±)-anti-DB[a,l]PDE, is a potent and specific carcinogen in tongue and other oral tissues in mice. We hypothesize that chronic alcohol consumption will increase the carcinogenic potency of DB[a,l]P in the mouse oral cavity by multiple mechanisms including the depletion of glutathione (GSH) and increasing levels of covalent DB[a,l]PDE-DNA adducts. As an initial study to test our hypothesis, mice were fed Isocaloric Lieber-DeCarli-type liquid diets formulated by BioServ (Frenchtown, N.J.) with or without ethanol (35% of total calories, increased gradually from 0, 11, 22 to 35%). After 3 weeks, mice were treated with 2 daily doses of DB[a,l]P (240 nmol each) and/or tobacco smoke particulates (TSP, 2R4F, 2.5 mg/mouse). Mice were sacrificed 24 hrs later and DB[a,l]PDE-DNA adduct levels were quantified by our recently developed LC-MS/MS method (Chem. Res. Toxicol. 2011, 1297-303). We showed that alcohol consumption significantly increased the levels of (-)-anti-trans-DB[a,l]P-dA in the absence of TSP (25%) or in the presence of TSP (75%). We also demonstrated that GSH levels in buccal mucosa were decreased (38%) in mice fed with liquid diet (35% calories from ethanol) compared with mice fed with control diet (0.89±0.13 μmol/g vs 1.23±0.17 μmol/g). Collectively, our preliminary results support our hypothesis that alcohol consumption will increase the carcinogenic potency of DB[a,l]P by altering the metabolic detoxification via depleting GSH and increasing DNA damage in oral tissues of mice. Citation Format: Shang-Min Zhang, Kun-Ming Chen, John R. Richie, Ana Calcagnotto, Cesar Aliaga, Arthur Berg, Yuan-Wan Sun, Arun K. Sharma, Shantu Amin, Karam El-Bayoumy. Effect of alcohol on DB[a,l]P, an environmental pollutant and a tobacco smoke constituent, on DNA adduct formation in mouse oral tissues. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3602. doi:10.1158/1538-7445.AM2013-3602