Extracellular Matrix Regulation of Estrogen Receptors in Mouse Mammary Cells

摘要

Our previous results have shown that the basement membrane (BM) regulated the expression and function of estrogen receptor-alpha (ERa) in mouse mammary epithelial cells. New results shown here indicate that the presence of lactogenic hormones was required for the regulatory effect of BM on ERa levels. We present evidence that cell adhesion to the BM components collagen-IV, through alpha 2 and beta 1 integrin subunits and laminin-l, through alpha 2, alpha 6 and beta 1 subunits are the relevant interactions responsible for transducing the signal of the BM that increases ERa expression. On the other hand, BM- induced changes in cell proliferation and cell morphology were not involved. Thus, the changes observed in ER expression and estrogenic effect when mammary epithelial cells are removed from the gland and placed in culture could be due to the disruption of the tissue organization and, in particular, to the lack of cell- matrix interactions on tissue culture plastic. Our system model could be useful to better understand the mechanisms involved in the regulation of ER expression and function during mammary gland development and breast tumor progression.