Abstract 4774: Epimorphin inhibits mammary epithelial cell apoptosis through induction of IKBKE

Epimorphin is a stromally produced factor that plays a role in normal mammary branching morphogenesis, but deregulated expression of epimorphin can have oncogenic consequences, although the oncogenic processes activated by epimorphin have not been elucidated. We had previously found that treatment of cultured mammary epithelial cells with epimorphin blocked activation of cell death pathways by a variety of apoptotic stimuli. These results implicated a potential role for epimorphin for inhibition of cellular apoptosis, a critical stage of tumor development. To identify potential mediators by which epimorphin could be affecting cell death pathways, we used a transcriptional profiling approach comparing mammary epithelial cells treated with epimorphin versus untreated cells. We found that epimorphin treatment led to significantly increased expression of IKBKE, which inhibits apoptosis through activation of NF-kappaB and which has recently been characterized as a key breast cancer oncogene. We found that epimorphin specifically blocks induction of apoptosis and activation of caspase-3 in cells treated with tumor necrosis factor-alpha, and that this activity was linked to epimorphin-mediated activation of IKBKE. We also found that knockdown of IKBKE blocked epimorphin-mediated induction of branching morphogenesis, implicating activation of IKBKE by epimorphin as a critical function for its normal morphogenic activities as well. These studies provide insight into an additional and unexpected linkage between mammary gland developmental processes and breast cancer progression. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4774. doi:10.1158/1538-7445.AM2011-4774