RESUMO
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 de-tected 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), phosphati-dylinositol 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 ex-pression 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 G1phase and promote apoptosis.The mechanism is related to the inhibition of PI3K/Akt signaling pathway.