Estrogens, Cell Proliferation and Breast Cancer

摘要

Estrogens are potent mitogens in some target tissues including the mammary gland, where they play a pivotal role in normal development and in the initiation and progression of mammary carcinoma. The demonstration that estrogen-induced mitogenesis is associated with an increased rate of progression through G_1 phase of the cell cycle has focused attention on the estrogen regulation of molecules that control G_1 to S phase progression. Steroid-responsive breast cancer cells pretreated with pure estrogen antagonists arrest in Go and respond to estrogen with synchronous progression into S phase. This process is preceded by increased expression of c-Myc and cyclin Dl, with consequentactivationofcyclinDl-Cdk4andcyclinE-Cdk2 complexes.