The regulation of estrogen receptor expression and function in human breast cancer.

Abstract

Estrogen and estrogen receptor (ER) play an important role in the development and function of the mammary gland. During mammary gland development, the hypothalamus and pituitary gland signal changes in the level of plasma estrogen, which is associated with proliferation of the mammary epithelial cells, leading to branching of ducts and formation of alveolar structures called lobules. Normal mammary epithelial cells express low basal levels (0-37 fmol/mg cytosol protein) of ER, and immunohistochemical studies show that about 7% of normal breast epithelial cells stain positively for ER [1,2]. These levels fluctuate during the menstrual cycle in conjunction with the cyclic changes in estrogen [3]. Definitive evidence that ER plays a pivotal role in normal mammary development was demonstrated using transgenic mice that were homozygously deleted for the gene. Adult female ER knockout mice develop mammary glands with only vestigial ducts present at the nipples [4].KeywordsEstrogen ReceptorHuman Breast Cancer Cell LineEstrogen Receptor GeneHuman Estrogen ReceptorEstrogen Receptor ProteinThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.