Objective:To construct a expression vector of EGFR specific siRNA and transfect it into human ovarian cancer cell line SKOV3

then to evaluate the effect of RNA interference(RNAi) on the target gene expression and radiosensitivity of the cell line.Methods:EGFR sh-RNA was synthesized in vitro and transfected into SKOV3 cells with lipofectamine technique and then the positive clones were selected by G418.The positive RNA interference cell line

negative RNA interference cell 1ine and the normal control cell 1ine were included in the study.RT-PCR and Western Blot technique were performed to detect the inhibitory effect of RNAi on EGFR mRNA level and protein level

respectively.Three kinds of cell lines were exposed to different doses of radiation.Cell survival curve was drawn by means of MTT method.Results:The expression of EGFR gene was surpressed obviously in the specific sequence shRNA group

and EGFR mRNA and protein surpression rates were 77.5% and 76.1%

respectively;Sequence-specific shRNA-EGFR can significantly enhance the radiosensitivity of ovarian cancer cells

and significant statistical differences existed among the three groups(P<0.01).Conclusion:The experiments in vitro confirmed that EGFR gene silenced by RNAi can significantly enhance the radiosensitivity of ovarian cancer SKOV3 cells.