RON receptor tyrosine kinase as a critical determinant in promoting tumorigenic behaviors of bladder cancer cells through regulating MMP12 and HIF-2α pathways

The RON receptor tyrosine kinase is critical in the pathogenesis of various cancer types, however, its role in bladder cancer invasive growth is still largely unknown. Here, we found that over 90% of bladder cancer samples exhibit elevated levels of RON expression, with significantly higher expression levels observed in invasive bladder cancer compared to non-invasive bladder cancer. In vitro, RON activation resulted in increased bladder cancer cell migration and invasiveness. Results from mRNA sequencing and transcriptome analysis further demonstrated that MMP12, a downstream molecule of RON, is functionally involved in regulating RON-mediated bladder cancer cell migration and invasiveness. The underlying mechanism appeared to be the RON-mediated inhibition of HIF-2α ubiquitination, which is channeled through the activation of the JNK signaling pathway. Consequently, the activated JNK pathway increased MMP12 expression, ultimately driving bladder cancer cell migration and invasion. As evident in bioinformatics and dual-luciferase reporter assays, the RON mRNA at its 3'-untranslated regions specifically interacted with hsa-miR-659-3p. The binding of hsa-miR-659-3p downregulated the RON gene expression, attenuating the receptor-mediated tumorigenic activities of bladder cancer cells in vitro and in vivo. In conclusion, aberrant RON expression in bladder cancer cells and MMP12 and HIF-2α activities form a functional axis that causes increased bladder cancer cell migration and invasion. The fact that hsa-miR-659-3p downregulates RON expression indicates its critical role in attenuating RON-mediated tumorigenic effect on bladder cancer cells. These findings highlight the importance of RON targeting as a therapeutic means for potential bladder cancer therapy.