Deregulated Estrogen Receptor α Expression in Mammary Epithelial Cells of Transgenic Mice Results in the Development of Ductal Carcinoma <i>In situ</i>

Abstract

Abstract A conditional tetracycline-responsive transgenic mouse model with deregulated estrogen receptor α expression in mammary epithelial cells developed ductal hyperplasia (DH), lobular hyperplasia, and ductal carcinoma in situ (DCIS) by 4 months of age. Higher proliferative rates were found in both normal and abnormal ductal and lobular structures. DH and DCIS but not normal ductal structures showed an increased percentage of cells with nuclear-localized cyclin D1. No differences in either the prevalence or extent of these phenotypes following exogenous 17β-estradiol treatment were found suggesting that alteration of ERα expression was the rate-limiting factor in initiation of DH, lobular hyperplasia, and DCIS.