Wenjing Zhang, Lili Zhi, Tian Huang, Lingya Feng, Chaoqun Chen, Huanhuan Wei, Xiaolong Liu, Lei Chen, Jinrui Zhang, Ge Zhang, Baofeng Zhao, Rong Liu, Dan Chen, Yangfan Qi, Yang Wang
Deregulated alternative splicing (AS) is a hallmark of hepatocellular carcinoma (HCC), yet the specific splicing factors driving oncogenic programs remain largely uncharacterized. Here, we identify RNA-binding motif protein 25 (RBM25) as a potent oncogenic driver that is overexpressed in HCC and correlates with dismal patient prognosis. Functionally, RBM25 depletion impairs HCC progression across in vitro models, in vivo xenografts, and patient-derived organoids. Integrated transcriptomic and interactome profiling reveals that RBM25 orchestrates a specific AS landscape, most notably promoting exon 13 inclusion of MYPT1. Mechanistically, RBM25 recruits PRPF40A to facilitate the production of the oncogenic MYPT1-L isoform. This isoform switch acts as a molecular stabilizer for the transcriptional co-activator YAP, thereby sustaining Hippo pathway dysregulation and tumor growth. Finally, a high-throughput screen of the US drug collection identified candicidin as a small-molecule inhibitor that suppresses RBM25 expression, effectively phenocopying RBM25 knockdown. Our findings define the RBM25-MYPT1-YAP axis as a critical vulnerability in HCC and nominate RBM25 as a viable prognostic biomarker and therapeutic target.