The MST4–14-3-3ζ complex promotes pancreatic cancer by activating YAP

The mammalian STE20-like kinase 4 (MST4) has been implicated as a potential oncogene in various cancers, including pancreatic cancer (PC). However, the precise mechanisms through which MST4 promotes PC malignancy remain incompletely understood. A Biotin identification (BioID)-based proximity labeling approach was employed to identify key MST4-interacting molecules in human PANC-1 pancreatic cancer (PC) cells, followed by cell migration assay to validate the synergistic promotional effect of the MST4-interacting complex on PC cell migration. Direct binding between MST4 and its interacting partners was confirmed via microscale thermophoresis (MST) and isothermal titration calorimetry (ITC), with further validation through X-ray crystallographic structural analysis. The efficacy of rationally designed peptides targeting this interaction was evaluated in both in vitro cell models and in vivo xenograft mouse models. In this study, we demonstrate that MST4 forms a phosphorylation-dependent complex with 14-3-3ζ, leading to Yes-associated protein (YAP) activation and synergistic enhancement of PC cell migration. We observed significant upregulation of both MST4 and 14-3-3ζ in PC patient samples, which correlated strongly with YAP activation and poor prognosis. Structural analysis revealed the detailed interface of the MST4–14-3-3ζ complex, facilitating the rational design of peptide inhibitors that disrupt this interaction. These peptides effectively suppressed YAP activation and exhibited potent anti-tumor effects both in vitro and in vivo. Our findings establish the MST4–14-3-3ζ complex as a critical regulator of YAP signaling that synergistically promotes PC cell migration. Furthermore, rationally designed peptides targeting this MST4–14-3-3ζ interaction represent a promising therapeutic strategy for pancreatic cancer and warrant further clinical exploration.