塞来昔布通过PI3K/Akt通路调控胃癌细胞凋亡

探讨塞来昔布通过PI3K/Akt信号通路调控胃癌细胞凋亡的机制。方法：塞来昔布体外处理人胃癌细胞株SGC-7901后，透射电镜观察细胞超微结构的改变，实时荧光定量RT-PCR法和Western Blot法检测蛋白激酶B（Akt）、天冬氨酸特异性半胱氨酸蛋白酶-8（Caspase-8）、Caspase-9的表达。结果：塞来昔布处理细胞后，透射电镜下观察到典型凋亡小体和自噬体；实验组Akt mRNA表达水平的改变无统计学意义，P-Akt蛋白的表达下调并呈时间和剂量依赖性，差异有统计学意义（P<0.05或P<0.01）；Caspase-8 mRNA表达水平上调，呈时间和剂量依赖性，差异有统计学意义（P<0.05或P<0.01）；Caspase-9 mRNA表达水平较对照组均上调，但125 μmol/L塞来昔布作用24 h组mRNA表达量与对照组相比差异无统计学意义，48 h和72 h组与对照相比差异有统计学意义（P<0.05或P<0.01）。塞来昔布作用72 h后，75 μmol/L组Caspase-9 mRNA表达量与对照组相比差异无统计学意义，100 μmol/L和125 μmol/L组与对照相比差异有统计学意义（P<0.05或P<0.01）；procaspase-8和procaspase-9蛋白被活化，表达量下调，呈时间和剂量依赖性，差异有统计学意义（P<0.05或P<0.01）。结论：1）塞来昔布可能通过PI3K/Akt通路诱导细胞凋亡和细胞自噬两种程序性死亡方式导致细胞死亡。2）塞来昔布诱导胃癌细胞凋亡的分子机制为线粒体途径和死亡受体途径。

COX-2 Regulation of Apoptosis in Human Gastric Cancer Cells via the PI3K/Akt Signaling Pathway

Abstract Objective: To investigate the mechanism of celecoxib regulation on the apoptosis of human gastric cancer cell via the PI3K/Akt signaling pathway. Methods: After in vitro celecoxib treatment of the SGC-7901cell line, transmission electron microscopy (TEM) was used to observe the morphologic changes in cellular ultrastructure. Real-time quantitative polymerase chain reaction and Western blot analysis were used to analyze the changes in the mRNA and the protein levels of Akt, caspase-8, and caspase-9 in SGC-7901 cells after celecoxib treatment. Results: Apoptotic changes, such as nuclear envelope subsidence, chromatin margination, crescent formation of the nucleus, apoptotic bodies, and autophagosomes, were observed under TEM. Interestingly, intense autophagic vacuolization and autophagosomes were detected in the regional cytoplasm of the affected cells. There was no statistically significant change in Akt mRNA and p-Akt protein expression in the experiment group. There was a decrease in p-Akt protein expression in a time-dose dependent manner. The changes were statistically significant ( P < 0.05 or P < 0.01 ). Caspase-8 mRNA expression increased sharply in a time-dose dependent manner and the change was statistically significant ( P < 0.05 or P < 0.01 ). Caspase-9 mRNA expression increased in the experimental group compared with the control; however, no statistically significant difference between the changes in caspase-9 mRNA levels in the group treated with 125 μmol/L celecoxib for 24 h and those in the control group. Significant differences were observed between the caspase-9 mRNA expression in the group treated with 125 μmol/L celecoxib for 48 and 72 h and those in the control group ( P < 0.05 and P < 0.01 ). At 72 h after celecoxib treatment, no statistically significant difference in caspase-9 mRNA expression was observed between the group treated with 75 μmol/L and the control group. Significant differences were found between the caspase-9 mRNA expression in the groups treated with 100 μmol/L and with 125 μmol/L and those in the control ( P < 0.05 and P < 0.01 ). The procaspase-8 and procaspase-9 proteins were activated, and the protein expression decreased. The expression was affected in a time-dose dependent manner, with significant differences among the groups ( P < 0.05 or P < 0.01 ). Conclusion: 1) Celecoxib may result in cell death via two mechanisms, namely, apoptosis and autophagic cell death induced through the PI3K/Akt signaling pathway. 2) The mechanisms by which celecoxib induces apoptosis are the death-receptor pathway and the mitochondrial pathways.