EDNRA Forms a Positive Feedback Loop with the Hippo/YAP Axis to Drive Triple-Negative Breast Cancer Progression.

Sustained Hippo/Yes-associated protein (YAP) activation drives triple-negative breast cancer (TNBC), but druggable upstream regulators remain unclear. We investigated G protein-coupled receptors (GPCRs) as membrane inputs for YAP activation. TCGA-based Hippo/YAP signature analysis, marketed-drug GPCR annotation, and siRNA screening using connective tissue growth factor (CTGF) identified endothelin receptor type A (EDNRA). EDNRA function was tested by knockdown, overexpression, endothelin-1 (ET-1) stimulation, and atrasentan blockade in TNBC cells and xenografts. YAP regulation was examined by immunoblotting, RT-qPCR, TEAD reporter assays, subcellular localization, docking, co-immunoprecipitation, mutagenesis, ChIP-qPCR, and CRISPRi. EDNRA correlated with Hippo/YAP signatures, adverse clinical features, and poor outcome. EDNRA depletion or atrasentan suppressed proliferation, migration, stem-like populations, and xenograft growth, whereas EDNRA overexpression or ET-1 had opposite effects. Mechanistically, EDNRA reduced YAP Ser127 phosphorylation, promoted nuclear YAP accumulation, and enhanced TEAD transcription through Gαq/11-Rho/ROCK-LATS signaling. Mutating predicted EDNRA-Gαq/11 interface residues impaired YAP activation and tumor-promoting activity. Reciprocally, YAP/TEAD4 enhanced EDNRA transcription through an enhancer-associated region. Atrasentan also sensitized TNBC cells to paclitaxel and produced positive zero interaction potency (ZIP) synergy scores. EDNRA establishes a druggable positive feedback loop with Hippo/YAP signaling and represents a potential therapeutic vulnerability in YAP-driven TNBC.