Interactome analysis reveals endocytosis and membrane recycling of EpCAM during differentiation of embryonic stem cells and carcinoma cells

Summary Transmembrane epithelial cell adhesion molecule (EpCAM) is expressed in epithelia, carcinoma, teratoma, and embryonic stem cells (ESC). EpCAM displays spatiotemporal patterning during embryogenesis, tissue morphogenesis, cell differentiation, and epithelial-to-mesenchymal transition (EMT) in carcinomas. Potential interactors of EpCAM were identified in murine F9 teratoma cells using a SILAC-based proteomic approach (n = 77, enrichment factor > 3, p-value ≤ 0.05). KEGG- and GO-terms revealed interactions with regulators of endosomal trafficking and membrane recycling, which were further validated for Rab5, Rab7, and Rab11. Endocytosis and membrane recycling of EpCAM were confirmed in mF9 cells, E14TG2α ESC, and Kyse30 carcinoma cells. Reduction of EpCAM during mesodermal differentiation and TGFs-induced EMT correlated with enhanced endocytosis and block or reduction of recycling in ESC and esophageal carcinoma cells. Hence, endocytosis and membrane recycling are means of regulation of EpCAM protein levels during differentiation of ESC and EMT induction in carcinoma cells.