Relationship between P53 and survivin in human lung cancer cells

Objective:To observe the inhibitory effects of survivin-specific siRNA on human lung cancer cell lines with different P53 statuses,and to analyse the relationship between P53 and survivin in vitro.Methods:A549(wild-type P53)and H1299(P53 absent)cells were transfected with chemosynthetic survivin siRNA.The effect of siRNA on cell proliferation was analysed by MTT assay.The changes of cell cycle and apoptosis were examined by flow cytometry.The expression of survivin mRNA was detected by RT-PCR.The protein expression of survivin,P53,P21 and PARP was examined by Western blotting.Results:Endogenous survivin level in A549 cells was lower than that in H1299 cells.The mRNA and protein expression of survivin was significantly lower in siRNA group than in blank control group and non-silencing siRNA group(P0.01).Survivin-specific siRNA significantly inhibited the growth and proliferation of both A549 and H1299 cells in a concentration dependent manner(P0.05),but the inhibitory effect was earlier and more efficient in A549 cells than in H1299 cells.Survivin-specific siRNA produced an increase in the G_1 fraction and a decrease in S fraction in the two cell lines,with the changes in the latter more evident.Apoptosis was found in A549 cells;PARP was cleaved and P21 and P53 protein was increased in A549 cells.The above changes were not obvious in H1299 cells. Conclusion:Endogenous survivin levels in A549(wild-type P53)cells is lower than that in H1299(without P53)cells. Inhibition of survivin by transfecting survivin siRNA can significantly up-regulate P53 protein expression in A549 cells.The effects of survivin siRNA on the cell growth,apoptosis and expression of some proteins are more prominent in A549 than in H1299 cells,suggesting that survivin and P53 might inhibit each other.