E-cadherin directly contributes to PI3K/AKT activation by engaging the PI3K-p85 regulatory subunit to adherens junctions of ovarian carcinoma cells
- 19 January 2009
- journal article
- Published by Springer Science and Business Media LLC in Oncogene
- Vol. 28 (9), 1206-1217
- https://doi.org/10.1038/onc.2008.470
Abstract
E-cadherin (cadh), a member of a family of integral membrane glycoproteins that represent the major component of adherens junctions (AJs), mediates cell–cell adhesion through the calcium-dependent homophilic interaction of its extracellular domain. Metastatic human carcinomas frequently lose E-cadh expression, whereas epithelial ovarian cancer (EOCs) maintain properties characteristic of Müllerian epithelium during tumor progression, including E-cadh expression. Here, we examined the potential role of cell–cell contacts in EOCs through E-cadh homophilic interactions in PI3K/AKT activation whose altered signaling has been implicated in EOC pathogenesis. We show that E-cadh is predominantly expressed at cell–cell contacts and its functionality is necessary and sufficient for the activation of the PI3K/AKT pathway. E-cadh knockdown and phosphoinositide-3-kinase (PI3K) inhibition complement each other in impairing cell-cycle progression and proliferation of ovarian carcinoma cells. E-cadh is stably bound to the PI3K complex, and the de novo formation of E-cadh/β-catenin complexes following calcium deprivation and subsequent calcium restoration recruits the PI3K p85 subunit to the site of the cell–cell contacts. The finding that E-cadh-mediated AJ formation contributes to PI3K/AKT activation in EOC cells by a mechanism that appears to be restricted to these cells provides the underpinning for therapeutic strategies that exploit PI3K inhibition to halt EOCs.Keywords
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