下调XBP1基因表达对脑胶质瘤细胞活力和凋亡的影响

目的:探讨下调X盒结合蛋白1(XBP1)表达对脑胶质瘤细胞活力和凋亡的影响。方法:q PCR检测脑胶质瘤组织中XBP1的m RNA表达。将干扰XBP1表达的小干扰RNA(XBP1-si RNA组)转染人脑胶质瘤U251细胞,同时设置正常对照(control)组(细胞无特殊处理)和阴性对照(NC-si RNA)组(转染不具有任何干扰作用的si RNA),转染48 h后,用q PCR检测3组细胞中XBP1的m RNA表达;Western blot检测XBP1、增殖细胞核抗原(PCNA)、B细胞淋巴瘤/白血病-2(Bcl-2)、Bcl-2相关X蛋白(Bax)、细胞周期素D1(cyclin D1)、磷脂酰肌醇3-激酶(PI3K)和磷酸化Akt(p-Akt)蛋白水平;CCK-8法检测细胞活力;流式细胞术检测细胞周期及凋亡。结果:XBP1在脑胶质瘤中的表达显著高于瘤旁组织(P0.05);转染XBP1-si RNA后,细胞中XBP1的m RNA及蛋白表达均显著降低(P0.05);NC-si RNA组细胞活力、细胞周期变化、细胞凋亡率及PCNA、Bcl-2、Bax、cyclin D1、PI3K和p-Akt的蛋白水平与control组比较差异无统计学显著性;XBP1-si RNA组细胞活力、S期细胞及PCNA、Bcl-2、cyclin D1、PI3K和p-Akt蛋白水平均显著低于control组,细胞凋亡率、G0/G1期细胞及Bax蛋白表达均显著高于control组(P0.05)。结论:下调脑胶质瘤细胞XBP1基因表达可降低肿瘤细胞的活力,阻滞细胞于G1期,并促进细胞的凋亡,其机制可能与抑制PI3K/Akt信号通路有关。

Effect of down-regulation of X-box binding protein 1 gene expression on viability and apoptosis of glioma cells

AIM: To investigate the effect of down-regulation of X-box binding protein 1 (XBP1) expression on the viability and apoptosis of glioma cells. METHODS: The mRNA expression of XBP1 in the glioma tissues was detected by qPCR. Small interfering RNA (siRNA) interfering with XBP1 expression (XBP1-siRNA) was transfected into human brain glioma U251 cells. At the same time, control group (the cells without special treatment) and negative control (NC-siRNA) group (transfected with siRNA without any interference) were set up. The mRNA expression of XBP1 in the 3 groups 48 h after transfection was detected by qPCR. The protein levels of XBP1, proliferating cell nuclear antigen (PCNA), B-cell lymphoma/leukemia-2 (Bcl-2), Bcl-2-associated X protein (Bax), cyclin D1 (cyclin D1), phosphatidylinositol 3-kinase (PI3K) and phosphorylated Akt (p-Akt) were determined by Western blot. The cell viability was measured by CCK-8 assay. The cell cycle distribution and apoptosis were analyzed by flow cytometry. RESULTS: The expression level of XBP1 in the glioma tissues was significantly higher than that in the tumor adjacent tissues (P<0.05). The XBP1 expression at mRNA and protein levels was significantly decreased in the cells transfected with XBP1-siRNA (P<0.05). No statistically significant difference of the cell viability, cell cycle, apoptotic rate and the protein levels of PCNA, Bcl-2, Bax, cyclin D1, PI3K and p-Akt between NC-siRNA group and control group was observed. Compared with control group, the cell viability, S-phase cells and the protein levels of PCNA, Bcl-2, cyclin D1, PI3K, and p-Akt in XBP1-siRNA group were decreased significantly, and the apoptotic rate, G₀/G₁-phase cells and Bax protein expression were significantly increased (P<0.05). CONCLUSION: Down-regulation of XBP1 gene expression in brain glioma cells reduces the viability of cancer cells, blocks the cells in G₁ phase and promote apoptosis. The mechanism is related to the inhibition of PI3K/Akt signaling pathway.