TIAL1 regulates the Hippo pathway through an RNA-binding-independent mechanism.

The Hippo pathway is an evolutionarily conserved signaling cascade whose dysregulation is implicated in a wide range of diseases. While many RNA-binding proteins (RBPs) regulate this pathway through canonical functions such as modulating mRNA stability and translation, the potential for RBP-mediated regulation via non-canonical, RNA-binding-independent mechanisms remains poorly defined. Here, we report that the RBP TIAL1 exhibits oncogenic properties in hepatocellular carcinoma, promoting cancer cell proliferation, migration, and invasion. Mechanistically, TIAL1 directly interacts with the core Hippo component SAV1, disrupting the MST1-SAV1 interaction and thereby suppressing Hippo signaling and activating YAP. Notably, this regulatory function is independent of the RNA-binding activity of TIAL1. Furthermore, extracellular stimuli such as energy surplus and EGF significantly upregulate TIAL1 expression, linking microenvironmental cues to Hippo pathway dysregulation. Together, our results reveal a previously unrecognized, RNA-binding-independent mode of RBP-mediated regulation, in which TIAL1 serves as a molecular integrator that conveys extracellular signals to the Hippo pathway to drive hepatocellular carcinoma progression, providing potential avenues for therapeutic intervention.