Abstract: Background and purpose: Bladder cancer is a common tumor of urinary system, and the prognosis is poor when superficial bladder cancer develops into invasive bladder cancer. The study aimed to observe the effects of silencing rictor gene using RNA interference (RNAi) on the growth of human bladder cancer T24 cells in vitro and in vivo. Methods: Three rictor-RNAi expression vectors (1#, 2# and 3#) and one negative control vector were constructed. Monoclonal stable cells with significant interference effects were screened by transient transfection and stable transfection techniques. The effects of inhibition of rictor gene expression on the growth of T24 cells were studied using cell counting kit-8 (CCK-8) assay, cell scratch assay, flow cytometry (FCM) and subcutaneous tumor formation in nude mice. Results: We successfully constructed three lines of rictor-RNAi plasmid vectors and one line of negative control vector. 2# vector had the most effective RNAi. 2#-1 and 2#-2 single cell clones were selected after stable transfection with 2# vector. The cell proliferation inhibition rates of 2#-1 group and 2#-2 group were much higher compared with blank control group (P<0.05). The migration speed of 2#-1 group and 2#-2 group also became slower obviously (P<0.05). Compared with blank control group, cell cycle analysis showed that 2#-1 group and 2#-2 group induced accumulation of cells in G₁ phase (P<0.05), and cell death analysis showed that 2#-1 group and 2#-2 group induced cell death (P<0.05). The xenograft tumor formation in nude mice showed that the average volumes of cell implantation tumor in 2#-1 and 2#-2 groups were significantly lower compared with the blank group and the negative control group (P<0.001). Conclusion: The rictor-RNAi expression vectors were constructed successfully, and they can reduce rictor gene expression effectively. Inhibition of rictor gene expression can significantly suppress the proliferation of T24 cells, promote tumor cell death, induce G₁ phase cell cycle arrest, and effectively inhibit the growth of xenograft tumor in nude mice. The therapeutic strategy of RNAi silencing rictor gene may provide new ideas for the treatment of bladder cancer.

Key words: RNA interference, Rictor gene, Bladder cancer, Inhibit