程序性细胞死亡4基因增强胰腺癌细胞放射敏感性的研究

Programmed cell death 4 enhances radiosensitivity of pancreatic cancer cells

目的 探讨程序性细胞死亡4（PDCD4）对胰腺癌细胞放疗敏感性的影响及机制。方法 收集胰腺癌组织及对应的癌旁组织，采用RT-PCR和Western blot检测PDCD4表达水平。以人胰腺癌细胞Sw1990为研究对象，细胞转染PDCD4过表达载体（pIRES2-PDCD4组）、空载体（pIRES2组），同时以只加入转染试剂的细胞为未转染组，RT-PCR和Western blot检测PDCD4表达水平。细胞经放射处理后，流式细胞术检测细胞凋亡情况，细胞克隆实验检测细胞放射敏感性，Western blot检测细胞中β-连环蛋白、Wnt信号通路下游靶基因c-myc、活化的含半胱氨酸的天冬氨酸蛋白水解酶3（Cleaved Caspase-3）表达水平。结果 胰腺癌组织中PDCD4 mRNA和蛋白表达水平均明显低于癌旁组织（t=4.869、9.208，P〈0.05）。pIRES2-PDCD4组细胞中PDCD4 mRNA和蛋白表达水平均明显高于未转染组（t=9.074、18.927，P〈0.05）。照射处理后，pIRES2-PDCD4组细胞凋亡率及细胞中Cleaved Caspase-3水平均明显高于未转染组（t=3.670、4.086，P〈0.05），而细胞中β-连环蛋白、c-myc表达水平均明显低于未转染组（t=9.242、17.644，P〈0.05）。pIRES2-PDCD4组放射敏感性高于未转染组，增敏比为1.843。结论 PDCD4能够增加胰腺癌细胞放射敏感性，促进胰腺癌细胞凋亡，作用机制可能与Wnt信号通路有关。

Objective To investigate the effect and mechanism of programmed cell death 4 （PDCD4） on radiosensitivity of pancreatic cancer cells. Methods Pancreatic cancer tissues and corresponding adjacent tissues were collected, the expression level of PDCD4 was detected by RT-PCR and Western blot. Human pancreatic cancer cells Sw1990 were transfected with PDCD4 overexpression vector （group pIRES2-PDCD4）, empty vector （pIRES2 group）, and treated with transfection reagent, respectively. The expression level of PDCD4 was detected by RT-PCR and Western blot. After radiation treatment, cell apoptosis was detected by flow cytometry, cell survival was detected by clone assay, and the expression levels of β-catenin, c-myc and Cleaved Caspase-3 were detected by Western blot. Results The expression of PDCD4 mRNA and protein in pancreatic cancer tissues was significantly lower than that in adjacent tissues （t=4.869, 9.208, P〈0.05）. The expression of PDCD4 mRNA and protein in pIRES2-PDCD4 group was significantly lower than that in the non-transfection group （t=9.074, 18.927, P〈0.05）. After radiation, the apoptosis rate and Cleaved Caspase-3 level in the pIRES2-PDCD4 group were significantly higher than those in the non-transfection group （t=3.670, 4.086, P〈0.05）, while the expression levels of β-catenin and c-myc in the cells were significantly lower than those in the non-transfection group （t=9.242, 17.644, P〈0.05）. The radiosensitivity of pIRES2-PDCD4 group was higher than that of non-transfection group, and the sensitization ratio was 1.843. Conclusions PDCD4 can increase radiosensitivity and promote apoptosis of pancreatic cancer cells, to which the Wnt signaling pathway may be related.