The IGF2BP1 oncogene is a druggable m6A-dependent enhancer of YAP1-driven gene expression in tumor growth

The Hippo/YAP1 signaling pathway regulates normal development by controlling contact inhibition of growth. In cancer, YAP1 activation is often dysregulated, leading to excessive tumor growth and metastasis. We demonstrate that the RNA-binding protein IGF2BP1 impedes the repression of YAP1 by Hippo signaling in carcinomas. IGF2BP1 stabilizes YAP1 mRNA and enhances YAP1 protein synthesis through an m6A-dependent interaction with the 3’UTR of the YAP1 mRNA. This results in increased nuclear YAP1 accumulation in IGF2BP1-expressing ovarian cancer, boosting transcriptional activity and bypassing contact inhibition. Inhibiting IGF2BP1-mRNA binding using the small molecule BTYNB reduces YAP1 levels and transcriptional activity, leading to significant growth inhibition in carcinoma cells and ovarian cancer organoids. Conversely, SRC inhibition via Saracatinib only impacts epithelial-like tumor cells, suggesting that the impact of SRC is limited by the stalling of YAP1 at adherens junction. This is particularly significant in de-differentiated, rather mesenchymal carcinoma-derived cells, which exhibit high IGF2BP1 and YAP1 expression, rendering them less reliant on SRC -directed growth stimulation. In such invasive carcinoma models, the combined inhibition of SRC and IGF2BP1 or YAP1/TAZ by Verteporfin proved superior over monotherapies. These findings highlight the therapeutic potential of targeting IGF2BP1, a key regulator of oncogenic transcription networks. PolyA-RNA sequencing of SAS cells was performed to to demonstrate that the RNA-binding protein IGF2BP1 impedes the repression of YAP1 by Hippo signaling in carcinomas.