ANTP-SmacN7对肿瘤细胞的辐射增敏作用及其机制

目的 探讨ANTP-SmacN7融合蛋白对肿瘤细胞的辐射增敏作用及其机制。方法 合成ANTP-SmacN7融合蛋白并观察其细胞渗透能力，Western blot法检测辐射对XIAP表达量的影响，克隆形成实验观察ANTP-SmacN7融合蛋白的辐射增敏作用。Annexin V-FITC/PI双染法测定药物及射线对肿瘤细胞凋亡的影响，Western blot法检测ANTP-SmacN7阻断XIAP前后Caspase-8、Caspase-9和Caspase-3的变化。结果 ANTP-SmacN7融合蛋白可以进入细胞内，并在细胞内蓄积；辐射诱导肿瘤细胞体外XIAP表达量与肿瘤辐射敏感性呈负相关（r=0.82）；ANTP-SmacN7对肿瘤细胞有辐射增敏作用，增敏比为1.41；ANTP-SmacN7融合蛋白可促进4、8和10 Gy γ射线诱导的XIAP高表达肿瘤细胞的凋亡（t=-14.924、-7.294和-15.866，P<0.05）。辐射可诱导Caspase-3表达水平的升高，ANTP-SmacN7对Caspase-3蛋白表达水平不产生影响，但可增加活化Caspase-3的裂解片段的数量。结论 ANTP-SmacN7融合蛋白可通过诱导Caspase-3的活化降低肿瘤细胞的辐射抗性。

Radiosensitization effect and underlying mechanism of ANTP-SmacN7 fusion peptide on tumor cells

Objective To explore the sensibilization effect and underlying mechanism of ANTP-SmacN7 fusion peptide on tumor cell radiation. Methods ANTP-SmacN7 fusion protein was synthesized and its ability of cell permeation was detected. Colony formation assay was used to detect the survival fraction of tumor cells exposed to ANTP-SmacN7. Annexin V-FITC/PI assay was used to detect the cell apoptosis after radiation and ANTP-SmacN7 exposure. Western blot assay was used to detect the expressions of Caspase-8, Caspase-9 and Caspase-3 before and after ANTP-SmacN7 exposure as well as the expression of XIAP in the irradiated cells. Results There was a negative relationship between XIAP expression and radiosensitivity of tumor cells(r=0.82). ANTP-SmacN7 could be accumulated in tumor cells and enhanced cell radiosensitivity with a SER of 1.41. ANTP-SmacN7 could also accelerate the apoptosis in the cells highly expressing XIAP after irradiation with 4, 8 and 10 Gy (t=-14.924,-7.294 and -15.866, P<0.05). In addition, ANTP-SmacN7 could activate Caspase-3 but did not influence radiation-induced expression of Caspase-3 in the cells. Conclusion ANTP-SmacN7 fusion protein can weaken radioresistance of tumor cells by activating Caspase-3.