UHRF1 expression inhibition by RNA interference enhances the radiosensitivity of esophageal cancer cells

Objective To study the effect of UHRF1 expression inhibition by RNA interference on the radiosensitivity of esophageal cancer cell line TE-1 and its mechanism.Methods Short hairpin RNA (shRNA) targeting UHRF1 gene was introduced into TE-1 cells by lentivector-mediated transfer.The cells were divided into three groups:non-transfected group,negative control (NC)-shRNA-transfected group,and UHRF1-shRNA-transfected group.The mRNA and protein expression levels of UHRF1 in TE-1 cells were measured by RT-PCR and Western blot before and after transfection.After transfection and X-ray radiation,the radiosensitivity of TE-1 cells was evaluated by colony formation assay; the cell cycle and cell apoptosis were determined by flow cytometry; the γ-H2AX (as a marker of DNA damage) level was measured by Western blot.Results After transfection with UHRF1-shRNA,the mRNA and protein expression levels of UHRF1 were significantly decreased in TE-1 cells,as compared with those in the NC-shRNA-transfected group and non-transfected group (0.11 vs 0.96 and 0.98,F =124.21,P =0.000;0.10 vs 0.89 and 0.94,F =125.25,P =0.000).The UHRF1-shRNA-transfected group had sensitization enhancement ratios of 1.53 (D0 ratio) and 1.95 (Dq ratio).X-ray radiation could cause G2/M arrest and increase apoptotic rate and γ-H2AX expression in TE-1 cells.Compared with the two control groups,the UHRF1-shRNA-transfected group showed significantly less G2/M arrest (F =500.15,P =0.000),a significantly higher apoptotic rate (F =100.10,P =0.000),and significantly higher residual γ-H2AX expression (F =61.00,P =0.000) at 24 hours after X-ray radiation.Conclusions RNA interference can effectively inhibit the UHRF1 expression and enhance the radiosensitivity of TE-1 cells.The mechanism may be related to cell cycle regulation,cell apoptosis,and DNA damage repair. Key words: UHRF1 gene ;  Radiosensitivity ;  G2/M arrest ;  Apoptosis ;  DNA damage repair