| First Author | Bascom JL | Year | 2013 |
| Journal | Cancer Res | Volume | 73 |
| Issue | 18 | Pages | 5719-29 |
| PubMed ID | 23867473 | Mgi Jnum | J:204281 |
| Mgi Id | MGI:5532208 | Doi | 10.1158/0008-5472.CAN-13-0021 |
| Citation | Bascom JL, et al. (2013) Epimorphin is a novel regulator of the progesterone receptor isoform-a. Cancer Res 73(18):5719-29 |
| abstractText | Epimorphin/syntaxin-2 is a membrane-tethered protein localized extracellularly (Epim) and intracellularly (Stx-2). The extracellular form Epim stimulates morphogenic processes in a range of tissues, including in murine mammary glands where its overexpression in luminal epithelial cells is sufficient to drive hyperplasia and neoplasia. We analyzed WAP-Epim transgenic mice to gain insight into how Epim promotes malignancy. Ectopic overexpression of Epim during postnatal mammary gland development led to early side-branching onset, precocious bud formation, and increased proliferation of mammary epithelial cells. Conversely, peptide-based inhibition of Epim function reduced side branching. Because increased side branching and hyperplasia occurs similarly in mice upon overexpression of the progesterone receptor isoform-a (Pgr-a), we investigated whether Epim exhibits these phenotypes through Pgr modulation. Epim overexpression indeed led to a steep upregulation of both total Pgr mRNA and Pgr-a protein levels. Notably, the Pgr antagonist RU486 abrogated Epim-induced ductal side branching, mammary epithelial cell proliferation, and bud formation. Evaluation of Epim signaling in a three-dimensional ex vivo culture system showed that its action was dependent on binding to its extracellular receptor, integrin-alphaV, and on matrix metalloproteinase 3 activity downstream of Pgr-a. These findings elucidate a hitherto unknown transcriptional regulator of Pgr-a, and shed light on how overexpression of Epim leads to malignancy. |
