Objective    To study the effect of small interfering RNA (siRNA) targeting survivin gene on the growth of transplanted tumors of renal carcinoma in nude mice in vivo.     Methods    Human renal carcinoma 786-O cells were used to subcutaneously inoculate into BALB/c female nude mice to develop a transplanted tumor model of human renal carcinoma. When the tumor diameter reached 5 to 6 mm

forty tumor-carrying nude mice were randomly divided into eight groups (five for each group). Two groups of the mice were treated by survivin-specific double-stranded RNA (dsRNA) via intratumoral injection

i.e.

group A (pGenesil1.1-survivin1) and group B (pGenesil1.1-survivin2). Tumor volumes in each group were calculated every day. On the 18th day after the first intratumoral injection

all the mice were sacrificed and the tumors were taken out to undergo RT-PCR and Western blotting to detect survivin expression. Tumor cell apoptosis was detected by TUNEL assay.     Results    The mice in groups A and B indicated slower tumor growth

significantly smaller tumor volume (P0.05)

and lower survivin expression level (P0.05) in comparison with those in the control groups. The TUNEL results showed a large amount of apoptotic cells with tawny nuclei

condensed chromatin and irregular cell shapes in groups A and B (P0.01).     Conclusion    RNA interference can obviously and specifically down-regulate survivin gene expression

inhibit cell proliferation and induce cell apoptosis in the transplanted tumors of human renal carcinoma in nude mice.