Therapeutic inhibition of METTL3/miR-146a-5p-guided NOTCH pathway suppresses bladder cancer progression

Bladder cancer characterized by RNA methylation abnormalities and NOTCH pathway dysregulation exhibits high recurrence that remains the major obstacle for bladder cancer treatment. Targeting methyltransferase-like 3 (METTL3) and NOTCH signal is a potential strategy to block bladder cancer progression. However, the underlying mechanisms by which METTL3-manipulated NOTCH signal and its effect on bladder cancer tumorigenesis remain to be clarified. Here we showed that METTL3-guided m6A modification methylated pri-miR-146 at the flaking sequence, which was responsible for the pri-miR-146 maturation. Furthermore, NUMB/NOTCH2 axis was identified as the functional downstream target signal that mediated the pro-survival role of miR-146a-5p in bladder cancer cells. Therapeutically, the polypeptide melittin was demonstrated to induce apoptosis of bladder cancer cells in a METTL3-dependent manner. Importantly, METTL3 and miR-146a-5p were positively correlated with recurrence and poor prognosis of bladder cancer patient. Our studies indicate that METTL3/miR-146a-5p/NUMB/NOTCH2 axis could be a potential therapeutic target for recurrent bladder cancer treatment and METTL3 acts as a fate determinant that controls sensitivity of bladder cancer cells to melittin treatment. Overall design: Examination of miRNAs in T24 bladder cancer cells treated with or without melittin