Effect of inhibiting Survivin expression by RNA interference on radiosensitivity of SKBr-3 breast cancer cells

OBJECTIVE:To investigate the effect of inhibiting Survivin expression by RNA interference on the radiosensitivity of SKBr-3 breast cancer cells.METHODS:A recombinant eukaryotic expression vector pSUPER-S1 carrying the specific siRNA of Survivin gene was introduced by lipofectamine mediated gene transfection into cultured SKBr-3 cells.Stably transfected cell clones were collected and analyzed by RT-PCR to determine the level of Survivin mRNA.The protein level of Survivin was detected by Western blot.The cell cycle phases were determined by flow cytometry(FCM).The radiosensitivity of the cells was examined by colony forming assay,and the values of D0,Dq and N were estimated.RESULTS:In the experiment group,both the mRNA and protein expression levels of Survivin gene in the transfected SKBr-3 cells were reduced significantly,as detected by RT-PCR and Western blot.FCM analysis revealed that most of the transfected SKBr-3 cells were blocked in G1 phase of cell cycle 〔(74.03±8.91)%〕,which were more than those of the control group 〔(44.21±12.03)%〕,P0.05.The transfection rate in S phase 〔(17.11±4.96)%〕 was less than that in the control group 〔(43.12±8.64)%〕,P0.05.After the irradiation of different doses of γ-ray,the values of D0,N and Dq were obtained through the cell survival curves.It showed that the values of transfected SKBr-3 cells(D0=1.29,N=4.9,Dq=2.6) were lower than those in control group(D0=1.56,N=14.85,Dq=5.21) significantly(P0.05),which demonstrated that the radiosensitivity of these cells was enhanced.CONCLUSION:RNAi can markedly inhibit the expression of Survivin gene and subsequently increase the radiosensitivity of cancer cells so as to improve the therapeutic effect.