The interaction of b-arrestin1 with talin1 driven by endothelin A receptor as a feature of a5b1 integrin activation in high-grade serous ovarian cancer

Dissemination of high-grade serous ovarian cancer (HG-SOC) in the omentum and intercalation into a mesothelial cell (MC) monolayer depends on functional a5b1 integrin (Inta5b1) activity. Although the binding of Inta5b1 to fibronectin drives these processes, other molecular mechanisms linked to integrin inside-out signaling might support metastatic dissemination. Here, we report a novel interactive signaling that contributes to Inta5b1 activation and accelerates tumor cells toward invasive disease, involving the protein b-arrestin1 (b-arr1) and the activation of the endothelin A receptor (ETAR) by endothelin-1 (ET-1). As demonstrated in primary HG-SOC cells and SOC cell lines, ET-1 increased Intb1 and downstream FAK/paxillin activation. Mechanistically, b-arr1 directly interacts with talin1 and Intb1, promoting talin1 phosphorylation and its recruitment to Intb1, thus fueling integrin inside-out activation. In 3D spheroids and organotypic models mimicking the omentum, ETAR/b-arr1-driven Inta5b1 signaling promotes the survival of cell clusters, with mesothelium-intercalation capacity and invasive behavior. The treatment with the antagonist of ETAR, Ambrisentan (AMB), and of Inta5b1, ATN161, inhibits ET-1-driven Inta5b1 activity in vitro, and tumor cell adhesion and spreading to intraperitoneal organs and Intb1 activity in vivo. As a prognostic factor, high EDNRA/ITGB1 expression correlates with poor HG-SOC clinical outcomes. These findings highlight a new role of ETAR/b-arr1 operating an inside-out integrin activation to modulate the metastatic process and suggest that in the new integrin-targeting programs might be considered that ETAR/b-arr1 regulates Inta5b1 functional pathway.