Survivin and its spliced isoform gene expression is associated with proliferation of renal cancer cells and clinical stage of renal cancer

Background: Survivin has been implicated in inhibition of apoptosis. To date, alternatively spliced isoforms, Survivin-2α, -2B, -ΔEx3, -3B, have been described. We assessed the effect of survivin gene expression on the proliferation of renal cancer (RCC) cells, and studied the association of survivin and its spliced isoform gene expression levels with the clinical stage of RCC. Methods: Gene expression of survivin and its spliced isoform in RCC cells, Caki-1, were performed by RT-PCR. We knocked down the gene expression of Survivin using small interfering RNA (siRNA), and assessed the cell proliferation by MTS assay. Next, we quantified the gene expression levels of survivin and its isoform in nephrectomy samples using quantitative real-time PCR. Results: In Caki-1 cells, survivin and survivin-2α, -2B were expressed higher than survivin-ΔEx3. Decrease of Survivin gene expression by transfection of siRNA was accompanied by inhibition of the proliferation of Caki-1 cell with 36% decrease in comparison with negative control transfected cells (p < 0.01). In clinical RCC tissues, survivin expression levels in metastatic stage were significantly higher compared with those in distant metastasis stage (M0:M1 = 1:4.81, p = 0.014); survivin 2B gene expression levels in pT3 tumors were associated significantly higher than those in pT1 (pT1:pT3 = 1:4.50, p = 0.043). No significant differences were found in survivin-2α expression levels and the ratio of survivin-2B/survivin gene expression levels among any clinical stages. Conclusion: We first demonstrated the gene expression of survivin-2α in renal cancer cells, and also showed that survivin and its spliced isoforms had associations with renal cancer cell proliferation and distant metastases.