LncRNA MST1P2/miR-133b axis affects the chemoresistance of bladder cancer to cisplatin-based therapy via Sirt1/p53 signaling.

Although bladder cancer is commonly chemosensitive to standard first-line therapy, the acquisition of the resistance to cisplatin (DDP)-based therapeutic regimens remains a huge challenge. Noncoding RNAs (ncRNAs), including long noncoding RNAs (lncRNAs) and microRNAs, have been reported to play a critical role in cancer resistance to DDP. Here, we attempted to provide a novel mechanism by which the resistance of bladder cancer to DDP treatment could be modulated from the perspective of ncRNA regulation. We demonstrated that lncRNA MST1P2 (lnc-MST1P2) expression was dramatically upregulated, whereas miR-133b expression was downregulated in DDP-resistant bladder cancer cell lines, SW 780/DDP and RT4/DDP. Lnc-MST1P2 and miR-133b negatively regulated each other via targeting miR-133b. Both lnc-MST1P2 silence and miR-133b overexpression could resensitize DDP-resistant bladder cancer cells to DDP treatment. More important, miR-133b could directly target the Sirt1 3'-untranslated region to inhibit its expression. Inc-MST1P2/miR-133b axis affected the resistance of bladder cancer cells to DDP via Sirt1/p53 signaling. In conclusion, MST1P2 serves as a competing endogenous RNA for miR-133b to counteract miR-133b-induced suppression on Sirt1, therefore enhancing the resistance of bladder cancer cells to DDP. MST1P2/miR-133b axis affects the resistance of bladder cancer cells to DDP via downstream Sirt1/p53 signaling.