中文摘要：

目的 观察Tat-Smac N7融合肽对人肺癌细胞系H460和人食管癌细胞系EC109的辐射增敏作用,探讨其辐射增敏机制.方法 取对数生长期H460和EC109细胞,分为DAPI对照组、FITC-Smac N7和FITC-Tat-Smac N7组,荧光显微镜观察两种细胞不同时间药物入核情况.取对数生长期H460和EC109细胞,分为单纯照射组、照射联合Tat-Smac N7组,单纯照射组给予0、2、4、6 Gy照射,照射联合Tat-Smac N7组中Tat-Smac N7的浓度为20 μmol/L,WST-1测定Tat-Smac N7的辐射增敏作用.取对数生长期H460和EC109细胞,分为对照组、Tat-Smac N7组、单纯照射组和照射联合Tat-Smac N7组,吸收剂量为4 Gy,Tat-Smac N7浓度为20 μmol/L,细胞流式分析仪测定细胞不同时间的细胞凋亡率.结果 Tat-Smac N7融合蛋白进入2种细胞系后2h可以有蓄积,且这种蓄积可延续到24 h,而Smac N7则不能进入细胞.Tat-Smac N7能够增强H460和EC109细胞的辐射敏感性（F=22.2、13.2,P＜0.05）,照射联合Tat-Smac N7可明显增加辐射诱导的细胞凋亡率（24 h：F=9.32、5.86,P＜0.05;48 h：F =7.09、8.25,P＜0.05）.Tat-Smac N7联合照射后凋亡诱导效应具有时间依赖性.结论 Tat-Smac N7融合肽可促进肿瘤细胞的辐射敏感性,作为一种新的Smac蛋白类似物,有望用于肿瘤的辐射增敏治疗.

英文摘要：

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＆#39;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.