PROJECT SUMMARY Breast cancer is a complex disease, and despite years of research, much remains to be learned about its initiation and progression. In addition to genetic factors, breast cancer can also be impacted by external factors such as diet and chemicals. Hundreds of epidemiology studies have shown a positive correlation between breast cancer and moderate alcohol consumption. Moreover, epidemiological and experimental evidence suggest an interplay between estrogen and alcohol, although the precise relationship is not de?ned. Despite this evidence, how exactly alcohol contributes to breast cancer and synergizes with estrogen remain poorly understood. In general, many of the molecular factors that are involved in cancer progression ultimately elicit their effects by causing changes in gene expression. A critical control point for regulating gene expression is at the level of mRNA transcription. Therefore, an understanding of alcohol-induced perturbations in the transcription levels of genes in cancerous breast cells would signi?cantly contribute to understanding the molecular basis for the increase in breast cancer development attributable to alcohol consumption. The proposed study will use genomic techniques to determine how transcription changes in response to alcohol treatment in three human cell types: 1) estrogen receptor positive breast cancer cells, 2) estrogen receptor negative breast cancer cells, and 3) normal breast cells. In addition, the impact of estrogen on the global alcohol-induced transcriptional changes will be determined in all three cell types. Importantly, the techniques that will be used ? BrU-seq and Pol II ChIP-seq ? will distinguish bona ?de transcriptional changes from changes in other biological pathways that impact cellular RNA levels. The proposed work will constitute an important contribution toward advancing understanding of the relationship between moderate alcohol consumption and increased breast cancer. Identifying the genes whose transcription levels change due to alcohol will reveal new potential mechanisms by which alcohol contributes to the progression to clinically signi?cant breast cancer. Hence, the results will build a much needed platform for future research to investigate the etiology of alcohol-induced breast cancer and its progression.