Abstract 3127: Cigarette smoke condensate (CSC) induces differential expression and promoter methylation profiles of critical genes involved in lung cancer in NL-20 lung cells in vitro: Short-term and chronic exposure

Abstract

Abstract Lung cancer is the leading cause of cancer deaths in the United States. Smoking accounts for a large number of those deaths. Recently, the Food and Drug Administration has been given authority to regulate any new cigarette products coming to market and further demonstrate the harm caused by constituents in cigarettes or those chemicals created from smoking. Establishing early diagnostic markers are critical to effective prevention programs. This study examined the effects of cigarette smoke condensate on expression and promoter methylation profile of critical genes involved in various stages of lung cancer development, such as E-cadherin (ECAD), O6-mehyl-guanine-DNA methyltransferase (MGMT), and RASSF1A. NL-20 cells were treated with 0.1, 1, 10 or 100 µg/ml of CSC for 24, 48 and 72 hrs for short-term exposures. ECAD showed a significant decrease in expression after 72 hrs with both 10 and 100 µg/ml CSC. This decrease in expression correlated to hypermethylation of the ECAD promoter at both concentrations using MSP analysis. MGMT expression increased only with the concentration of 100 µg/ml CSC at all time points. This correlated to an unmethylated profile of the promoter at this concentration. RASSF1A promoter profile was methylated in the control samples. However, when treated with 10 or 100 µg/ml CSC, an unmethylated promoter profile was noted. This correlated to increased expression of RASSF1A at both the 10 and 100 µg/ml concentrations. No changes were noted at 0.1 or 1 µg/ml of CSC in NL-20 lung cells. For chronic studies, the cells were exposed for 30 days with 10 or 100 µg/ml CSC, with media changes every three days adding new CSC. After 30 days, cells showed morphological changes associated with transformation. Foci were noted. These cells were further analyzed for further changes in critical genes involved in lung cancer. This study provides critical data showing epigenetic regulation of critical genes involved in DNA repair, invasion and tumor suppressor with treatment of lung cells with CSC. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3127. doi:1538-7445.AM2012-3127