YAP transduction drives triple-negative breast cancer aggressiveness through modulating the EGFR‒AKT axis in patient-derived xenograft cells.

Aside from the high prevalence of incidents of breast cancer, the high grade of heterogeneity and the dearth of standard treatment guidelines make triple-negative breast cancer (TNBC) the most refractory subtype. Though still in its infancy, the Hippo pathway has been known to play a critical role in tumorigenesis. However, the molecular mechanics through which the pathway exploits the breast cancer (BC) cell vulnerability are largely unexplored. In this study, we observed a relatively higher expression of the Hippo effector, yes-associated protein (YAP), in TNBC patients compared to non-TNBC patients. Thus, we sought to investigate the contribution of Hippo signaling in TNBC by focusing particularly on transducers of the pathway. Impeding YAP transactivation by means of RNA interference or pharmacological inhibition was carried out, followed by evaluation of the subsequent biological changes at the molecular level. We successfully translated the observed data into a TNBC patient-derived xenograft cell line (PDXC). We discovered that nuclear translocation of YAP was associated with TNBC aggressive characteristics and activated the EGFR-AKT axis. Here, we explored the putative role of the Hippo transducer in enhancing cancer hostility and observed that YAP transduction drives proliferation, migration, and survival of TNBC by preventing cellular apoptosis through mediating EGFR activation. These observations suggest that YAP represents a major vulnerability in TNBC cells that may be exploited therapeutically.