Estrogen receptor transcription and transactivation: Novel morphoregulatory functions for the adhesion receptor Ep-CAM in the mammary epithelium

bcr335 BCJ Meeting abstract Estrogen receptor transcription and transactivation: Novel morphoregulatory functions for the adhesion receptor Ep-CAM in the mammary epithelium Blazar M Cirulli V Prins F Litvinov SV

Department of Pathology and Division of Laboratory Animals, Leiden University Medical Center, Leiden, The Netherlands

The Whittier Institute for Diabetes, University of California San Diego, La Jolla, California, USA

Breast Cancer Res 23rd Congress of the International Association for Breast Cancer Research Meeting abstracts 23rd Congress of the International Association for Breast Cancer Research Düsseldorf, Germany

13–16 June 2001

1465-5411 2001 3 Suppl 1 A11 10.1186/bcr335 10 5 2001 29 5 2001 2001 BioMed Central Ltd bcr-3-s1-a11 Estrogen receptor transcription and transactivation Pierre Chambon

Ep-CAM, an epithelial cell-cell adhesion receptor, is often over-expressed in association with proliferation and remodeling in epithelial tissues. Development of the mouse mammary gland during pregnancy is associated with a progressive upregulation of Ep-CAM expression, eventually reaching very high levels at day 16 of pregnancy. This phenomenon is paralleled by a concomitant branching of the mammary ductal tree and a sustained epithelial cell proliferation. Using a MMTV-LTR/Ep-CAM transgenic mouse model, we demonstrate that forced expression of Ep-CAM in the mammary epithelium leads to an induction of budding and secondary branching of the glandular tree in virgin females. Interestingly, a complete cycle of gestation in the Ep-CAM transgenic mice results in extreme ductal hyperplasia/ductectasia and lobular hypoplasia, in combination with partially decreased differentiation of both ductal and alveolar (lobular) epithelial cells. Surprisingly, mammary gland involution is affected because of a decreased frequency of apoptotic figures and increased rate of cell proliferation. These results support novel morphoregulatory functions for the adhesion receptor Ep-CAM in epithelial tissue development and homeostasis.