BACKGROUNDBladder cancer is the most common type of urinary system tumours. It is frequently associated with genetic mutations that deregulate the cell cycle and render these tumours resistant to apoptosis. Survivin, a newly discovered member inhibitor of apoptosis protein (IAP) family in several human cancers, by inducing cell proliferation and inhibiting apoptosis is frequently activated in bladder cancer. We studied the influence of small interfering RNA (siRNA) targeting survivin on the biological behaviour of bladder cancer cells.

METHODSA double strand survivin target sequence specific siRNA was designed and synthesized. After transfection of bladder cancer cell line T24 by siRNA/liposome complex with increasing concentrations (50200 nmol/L), the transfectant cells were intratumourally injected at different doses (5 microg or 50 microg). The effects were measured in vitro and in vivo.

RESULTSThe selected siRNA efficiently down-regulated survivin mRNA expression in a dose and time dependent manner. The maximal effect was achieved at the concentration of 100 nmol/L, at which survivin expression level was down-regulated by 75.91%. The inhibition rate of cell growth was 55.29% (P < 0.01) and the markedly increased apoptotic rate was 45.70% (P < 0.01). In vivo intratumoural injection of 50 microg siRNA-survivin could notably prevent the growth of bladder cancer (P < 0.01) in xenografted animals.

CONCLUSIONThe application of siRNA-survivin could markedly inhibit survivin expression in bladder cancer cell line by inducing apoptosis and inhibiting the growth of the tumour. It may become a new gene therapy tool for bladder cancer.