Role of estrogen receptor on tumor progression in human breast cancer

Growth and proliferation of estrogen receptor (ER) positive breast cancer (BC) depend on endogenous estrogen. ER-targeted therapies down-regulate endogenous estrogen thereby blocking a response mediated by the hormone-activated receptor complex. Numerous genes are co-regulated with the ER in ER-positive BCs. The impact of these genes and the mechanism by which they contribute to growth inhibition are not well understood. We aim to characterize gene expression in different subtypes of cancer cells of the same tumors and in separate tumors. This will produce catalogues of differentially expressed genes for the different cell types which may contribute to better understand the biology of breast cancer.