Abstract A5: Transient TGFβ exposure reprograms mouse mammary epithelial cells in vitro and in vivo

Transforming growth factor beta (TGFβ) has been shown to inhibit growth of normal breast epithelium, but promotes aggressive behaviors in breast carcinomas. Normal breast epithelia are exposed transiently to increased levels of TGFβ during involution. During radiation therapy for breast cancer, the breast epithelium is also exposed transiently to TGFβ.While TGFβ restricts growth of most normal breast epithelia, it may have divergent effects on progenitor cells. The CDβgeo cells have been shown to be enriched for mammary progenitor cells (Deugnier et al., 2006). Treatment of CDβgeo cells with TGFβ1 resulted in modest decreases in E-cadherin levels after 14 days (TD0). However, withdrawal of TGFβ and passaging the cells over 14 days resulted in transdifferentiation (TD14). In contrast to the parental CDβgeo cells, the TD14 cells had decreased expression of E-cadherin (3‐fold, p Citation Information: Cancer Res 2009;69(23 Suppl):A5.