E-Cadherin Is a Structuring Component of Invadopodia in Pancreatic Cancer.

The appearance of hybrid epithelial-mesenchymal (E/M) cells expressing E-cadherin is favourable for the establishment of pro-invasive function. Although the potential role of E-cadherin in cancer invasion is now accepted, the molecular mechanisms involved in this process are not completely elucidated. To gain further insight, we focused our analysis on invadopodia formation, an early event in the invasion process. We used models of E/M hybrid cell lines, tissue sections and patient-derived xenografts from a multi-centre clinical trial. E-cadherin involvement in invadopodia formation was assessed using a gelatin-FITC degradation assay. Mechanistic studies were performed by using proteomic analysis, siRNA strategy and proximity ligation assay. We showed that E-cadherin is a critical component of invadopodia. This unexpected localization results from a synergistic trafficking of E-cadherin and MT1-MMP through a Rab vesicle-dependent pathway. Modulation of E-cadherin expression or activation impacted invadopodia formation. Moreover, colocalization of E-cadherin and Actin in "ring structures" as precursors of invadopodia reveals that E-cadherin is required for invadopodia structuration. E-cadherin, initially localised in the adherens junctions, could be recycled to nascent invadopodia where it will interact with several components enriched in invadopodia, such as Arp2/3, Cortactin or MT1-MMP. The trans-adhesive properties of E-cadherin are therefore essential for structuring invadopodia. This new localisation of E-cadherin and its unexpected role in cell invasion shine a new light on hybrid E/M transition features in tumoral invasion.