Abstract LB-432: Effect of chronic nicotine consumption on NNK-induced lung tumors in the A/J mouse

Abstract

Abstract Nicotine replacement therapy (NRT) is often used to maintain smoking cessation. Some individuals continue to use NRT for years after smoking cessation, and some NRT users continue to smoke. It is important to understand the impact of chronic nicotine use on lung cancer risk. Therefore, we determined the effect of nicotine administration on NNK-induced lung tumors in the A/J mice. P450 2A enzymes are key catalysts in NNK bioactivation, and nicotine is both an inhibitor and a mechanism based inactivator of P450 2A-catalyzed nicotine metabolism. These data suggest nicotine might protect from NNK-induced tumorigenesis. However, several investigators have reported that nicotine inhibits apoptosis, enhances angiogenesis and enhances proliferation. We hypothesized that nicotine would prevent or delay initiation of NNK-induced tumors, but accelerate tumor growth by reducing apoptosis and promoting inflammation. To test this, female A/J mice were administered a single dose of NNK (100 mg/kg i.p) and 200 ug/ml nicotine in the drinking water. Nicotine was administered 2 weeks prior to NNK, 44 weeks after NNK, throughout the experiment, or without NNK treatment. There were several key outcomes of this study: Chronic nicotine consumption did not affect P450 2A5-catalyzed metabolism in the lung of liver. Nicotine administration alone for 44 weeks did not increase lung tumor multiplicity. Nicotine given before or after NNK administration did not increase, or decrease, tumor number or tumor size. There was also no difference in the number of carcinomas per mouse or the number of adenomas with dysplasia. In conclusion, nicotine consumption in the drinking water had no effect on the tumorigenicity of NNK in the A/J mouse. 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 LB-432. doi:10.1158/1538-7445.AM2011-LB-432