Objective To investigate the effect of ring finger protein 2(RNF2) gene on the radiosensitivity of esophageal carcinoma cell after X-ray irradiation.

Methods Three pairs of siRNA(siRNA1, siRNA2, and siRNA3) based on the sequences of the RNF2 mRNA were synthesized to transfect the cultured ECA109 cells as RNF2 siRNA groups, and a negative one was synthesized to be used as negative control(NC) group. The untransfected group was named as control group. The inhibitory effects of siRNA on the transcription and translation of RNF2 gene in esophageal cancer cells ECA109 were detected by RT-PCR and Western blot in different groups. We used flow cytometry assay to analyze cell cycle of the transfected cells, and examined cellular growth and radiosensitivity in vitro by MTT and clone formation assay.

Results The transcription and translation of RNF2 gene were inhibited after silencing the RNF2 gene. The mRNA and protein expression of RNF2 in RNF2 siRNA1 group were both significantly lower than the other groups. The proliferation of tumor cells in RNF2-siRNA group was obviously inhibited, compared with the other groups after the X-ray radiotherapy. The values of D0, Dq, and SF2 in RNF2 siRNA group were lower obviously than those in control group and NC group, while the value of extrapolation number N in RNF2 siRNA group was markedly higher than those in the latter, which showed higher radiosensitivity in RNF2 siRNA group. The percentage of G0/G1 phase in RNF2 siRNA group was higher than those in control group and NC group, while the percentage of S phase was lower than those in the latter.

Conclusion siRNA could effectively inhibit RNF2 gene expression in esophageal cancer cells ECA109, suppress the proliferation activity of cells and enhance the radiosensitivity combined with X-ray irradiation, followed by eliminating the cell cycle arrest at S stage after irradiation in vitro.