Pacsin 2-dependent N-cadherin internalization regulates the migration behaviour of malignant cancer cells

Cell migration is essential for both physiological and pathological processes such as embryonic morphogenesis, wound repair and metastasis of cancer cells. Collective cell migration is the coordinated movement of multiple cells connected with cadherin-based adherence junctions. Cadherins undergo dynamic intracellular trafficking and their surface level is determined by a balance between endocytosis, recycling and degradation. However, regulatory mechanisms of cadherin turnover in the collective cell migration remain to be elucidated. In this study, we show that a BAR domain protein pacsin 2 plays an essential role in collective cell migration by regulating the internalization of N-cadherin in human bladder cancer cells T24. Pacsin 2 and its associating GTPase dynamin 2 colocalized with N-cadherin at the cell periphery in T24 cells. Depletion of either pacsin 2 or dynamin 2 induced interdigitating cell-cell contacts enriched with N-cadherin. Imaging analyses of the wound healing assay showed that pacsin 2-depleted T24 cells migrated in a collective and directed manner in contrast with randomly migrating control cells. Furthermore, cell-surface biotinylation assay showed that internalization of N-cadherin is attenuated in pacsin 2-depleted cells. Interestingly, the GST-pulldown assay demonstrated that the SH3 domain of pacsin 2 binds to the cytoplasmic domain of N-cadherin, suggesting that surface levels of N-cadherin are regulated by pacsin 2-mediated endocytosis. These data support new insights into a novel endocytic route of N-cadherin in collective cell migration providing pacsin 2 as a possible therapeutic target for cancer metastasis.