Silencing of survivin expression leads to reduced proliferation and cell cycle arrest in cancer cells

Survivin is an anti-apoptotic gene that is overexpressed in most human tumors. RNA interference using short interfering RNA (siRNA) can be used to specifically inhibit survivin expression. Tumor cells were treated with a newly designed survivin siRNA, which was modified with 2'-OMe. Cellular survivin mRNA and protein levels were determined by real-time qRT-PCR and Western blot, respectively. Cell cycle and apoptosis were determined by flow cytometry. Cell proliferation was measured by MTT assay. Our data showed that the novel survivin-targeted siRNA could efficiently knockdown the expression of survivin and inhibit cell proliferation. Survivin mRNA was reduced by 95% after 48h treatment with 20nM siRNA. In addition, the siRNA could markedly arrest the cell cycle at the G2/M checkpoint and induce cellular apoptosis in a dose-dependent manner. The percentage of apoptotic cells reached 50% when treated with 40nM siRNA. In conclusion, we have identified a novel chemically modified siRNA against survivin that is highly efficient and delineated its mechanism of action, thus demonstrating a potential therapeutic role for this molecule in cancer. Further evaluation of this siRNA for therapeutic activity is warranted.