Epidemiologic studies have demonstrated that alcohol consumption enhances colorectal carcinogenesis especially in individuals with folate depletion and/or methylenetetrahydrofolate reductase (MTHFR) homozygous variant genotype, indicating that the co-carcinogenic effect of alcohol is conveyed through the folate mediated one-carbon metabolism, as well as advocating an interaction between alcohol and MTHFR gene, which maintains a balance between biological methylation and nucleotide synthesis. Recently, we identified the fact that chronic alcohol consumption induces hyperhomocysteinemia and genomic DNA hypomethylation in the rodent colon, indicating the potent effects that alcohol exerts on onecarbon metabolism and epigenetic phenomena, and subsequently lending that chronic alcohol consumption modifies critical gene expression through epigenetic changes and provides a co-carcinogenic milieu in the colonic mucosa. Our long-term goal is to find effective strategies for the chemoprevention of alcohol-associated cancer. The studies outlined in this proposal are aimed at defining epigenetic mechanisms by which alcohol consumption affects colorectal carcinogenesis. We therefore hypothesize that chronic alcohol consumption disturbs one-carbon metabolism in the colon and thereby alters epigenetic phenomena including DNA methylation and histone methylation as well as critical gene expression. We further hypothesized that conditions which alter the balance of one-carbon metabolism, such as folate depletion, aging and MTHFR ? polymorphism, aggravate these epigenetic phenomena induced by chronic alcohol consumption. This application is innovative because two proposed epigenetic phenomena, histone methylation and promoter DNA methylation, have never been explored for the study regarding the alcohol-associated carcinogenesis and the proposed epigenetic interaction between alcohol and MTHFR gene is a new concept that enables individually tailored chemoprevention by genotypes and nutrition status. Based on the results of this application we will apply for a research project grant to finalize the epigenetic effect of chronic alcohol consumption on colorectal carcinogenesis. If those studies can precisely define the epigenetic mechanism for alcohol-associated carcinogenesis, we can develop a new chemopreventive strategy for those cancers. ? ? ?
