RacGAP1-driven focal adhesion formation promotes melanoma transendothelial migration through mediating adherens junction disassembly

Melanoma cell migration across vascular endothelial cells is an essential step of tumor metastasis. Here, we provide evidence that RacGAP1, a cytokinesis-related Rho GTPase-activating protein, contributed to this process. Depletion of RacGAP1 with RacGAP1-targeting siRNA or overexpression of RacGAP1 mutant (T249A) attenuated melanoma cell transendothelial migration and concomitant changes of adherens junctions. In addition, RacGAP1 promoted the activations of RhoA, FAK, paxillin and triggered focal adhesion formation and cytoskeletal rearrangement. By overexpressing FAK-related non-kinase (FRNK) in endothelium, we showed that RacGAP1 mediated endothelial barrier function loss and melanoma transmigration in a focal adhesion-dependent manner. These results suggest that endothelial RacGAP1 may play critical roles in pathogenic processes of cancer by regulating endothelial permeability. •RacGAP1 promotes Lu1205 extravasation by increasing endothelial permeability.•Melanoma contact induces activations of RhoA, FAK and paxillin.•Activations of RhoA, FAK and paxillin are dependent on RacGAP1 phosphorylation.•RacGAP1 activation mediates focal adhesion assembly and actin stress fiber formation.•Overexpressing FRNK reduces endothelial junction breakdown and Lu1205 transmigration.