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Oncogene. 2009 Mar 5;28(9):1206-17. doi: 10.1038/onc.2008.470. Epub 2009 Jan 19.

E-cadherin directly contributes to PI3K/AKT activation by engaging the PI3K-p85 regulatory subunit to adherens junctions of ovarian carcinoma cells.

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1
Unit of Molecular Therapies, Department of Experimental Oncology, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.

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/beta-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.

PMID:
19151754
DOI:
10.1038/onc.2008.470
[Indexed for MEDLINE]

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