Radiosensitization in tumor cells induced by Tat-Smac N7 fusion peptide

Abstract

Objective To observe the radiosensitization effect of Tat-Smac N7 fusion peptide in EC109 and H460 cell lines, and to explore the mechanism of Tat-Smac N7 in radio sensitization. Methods H460 and EC109 cells were divided into DAPI group, and FITC-Smac N7 group, FITC-Tat-Smac N7 group. Fluorescence microscope was used to detect if the peptide had been entered into tumor cells at deferent times. H460 and EC109 cells were divided into radiation group and Tat-Smac N7 combined with radiation group. The cells were irradiated with 4 Gy γ-ray and the concentration of Tat-Smac N7 was 20 μmol/L. The proliferation of tumor cells was detected by WST-1 assay. Among control group, radiation group, Tat-Smac N7 group and Tat-Smac N7 combined with radiation group, apoptosis was detected by flow cytometry. Results Tat-Smac N7 could enter cells for 2-24 h, but Smac N7 couldn′t. Tat-Smac N7 promoted the radio sensitization of H460 and EC109 cells obviously (F=22.2, 13.2, P<0.05). The apoptosis of combined group was much higher than that of control (24 h: F=9.32, 5.86, P<0.05; 48 h: F=7.09, 8.25, P<0.05). The apoptosis in Tat-Smac N7 combined with radiation group varied with time-dependence. Conclusions Tat-Smac N7 fusion peptide showed remarkable radiosensitization in tumor cells. As a new Smac mimetic, Tat-Smac N7 was potential in radio sensitization therapy of tumor in the future. Key words: Smac protein; EC109; H460; Cell apoptosis; Radiosensitivity