MicroRNA-145 directly targets the insulin-like growth factor receptor I in human bladder cancer cells.

The insulin-like growth factor receptor I (IGF-IR) is a proto-oncogene with potent mitogenic and antiapoptotic activities. It has been reported that expression of IGF-IR is up-regulated in bladder cancer. Here, we assessed whether microRNA-145 (miR-145) regulates IGF-IR expression in bladder cancer. In our study, miR-145 was shown to directly target IGF-IR 3'-untranslated region (UTR) in human bladder cancer cells. Small interfering RNA (siRNA)- and miR-145-mediated IGF-IR knockdown experiments revealed that miR-145 promotes cell apoptosis, and suppresses cell proliferation and migration through suppression of IGF-IR expression. Taken together, our data suggest that miR-145 may inhibit bladder cancer initiation by affecting IGF-IR signaling.