[Influence of survivin gene repression by RNA interference on the radiosensitivity and chemosensitivity to cisplatin of cervical cancer cell HeLa].

OBJECTIVE: To observe the effect of survivin gene repression by RNA interference (RNAi) on the radiosensitivity and the chemosensitivity to cisplatin of cervical cancer cell HeLa. METHODS: The recombined eukaryotic expression plasmid pSilencer2.1-s2 containing human survivin gene small interference RNA (siRNA) was transfected into human cervical cancer cell line HeLa by using lipofectamine 2000. The expression of survivin gene mRNA and its protein was detected by semi-quantitative RT-PCR and western blot respectively. The changes of caspase-3 activity was assessed by kinase activity test. Cell apoptosis was examined by flow cytometry. The changes of cell radiosensitivity was observed by plate clone formation assay. Cell viability was examined by methyl thiazolyl tetrazolium (MTT) assay and 50% inhibitive concentration (IC(50)) of cisplatin was examined also. RESULTS: Compared with the cells which were transfected with negative control plasmid (HeLa-NC), pure plasmid (HeLa-U6 neo) and un-transfected cells (HeLa), the expression level of survivin gene mRNA and protein declined evidently in the cells transfected with pSilencer2.1-s2 plasmid (HeLa-s2), the expression inhibitory rates were (62.8 +/- 0.3)% and (60.1 +/- 0.5)%; the caspase-3 activity was enhanced and A(405) was 1.261 +/- 0.043 (P < 0.05); the apoptotic rate was increased obviously (29.23 +/- 1.41)% (P < 0.05). At the same dose of radiation, clone formation rate declined significantly (P < 0.05); at the same concentration of cisplatin, cell viability declined sharply and the IC(50) of cisplatin was (0.873 +/- 0.021) microg/ml (P < 0.05). CONCLUSION: Survivin gene repression by RNAi can enhance caspase-3 activity, induce cell apoptosis, significantly increase the radiosensitivity and chemosensitivity to cisplatin in human cervical cancer cell line HeLa.