Effects of curcumin on glioma cell U87 and its effects on cysteinyl aspartate-specific protease-3, cysteinyl aspartate-specific protease-9, B cell lymphoma/leukemia-2 and B cell lymphoma/leukemia-2 associated X protein

Objective To explore the effects of curcumin on glioma cell U87 and its effects on cysteinyl aspartate-specific protease (Caspase)-3, Caspase-9, B cell lymphoma/leukemia-2 (bcl-2) and bcl-2 associated X protein (bax). Methods The U87 cells were treated with curcumin solution. Methyl thiazol tetrazolium (MTT) assay was used to measure cell proliferation. Flow cytometry was used to examine cell apoptosis. Enzyme-linked immunosorbent assay was used to detect Caspase 3 and Caspase 8 levels in cell culture medium. Western blotting was used to detect the expression of bcl-2 and bax proteins. Results The proliferative rate of U87 cells at 24 h and 48 h in low dose curcumin group [(8.48±1.19)% and (11.89±1.39)%] and high dose curcumin group [(16.04±1.58)% and (25.63±1.66)%] was significantly lower than that in blank control group [(1.47±0.10)% and (1.39±0.19)%] (P<0.05). The proliferative rate of U87 cells at 24 h and 48 h cells in high dose curcumin group was significantly lower than that in low dose curcumin group (P<0.05). The proliferative rate of U87 cells at 48 h in high dose curcumin group and low dose curcumin group was significantly lower than that at 24 h in the corresponding groups (P<0.05). The apoptosis rate of U87 cells in low dose curcumin group and high dose curcumin group [(9.53±1.21)% and (20.52±2.35)%] was significantly higher than that in blank control group (2.22±0.14)% (P<0.05). The apoptosis rate of U87 cells in high dose curcumin group was significantly higher than that in low dose curcumin group (P<0.05). Caspase-3 and Casepase-8 levels in cell culture supernatant of low dose curcumin group [(156.35±29.63) and (158.35±25.36) ng/ml], and high dose curcumin group [(252.52±35.21) and (225.61±30.66) ng/ml] were significantly higher than those of blank control group [(50.63±10.36) and (78.23±11.35) ng/ml, P<0.05]. Caspase-3 and Casepase-8 levels in cell culture supernatant of high dose curcumin group were significantly higher than those of low dose curcumin group (P<0.05). The expression level of bcl-2 protein in U87 cells of low dose curcumin group (0.61±0.10 and 0.67±0.09) and high dose curcumin group (0.42±0.08 and 0.88±0.11) was significantly lower than that of blank control group (0.88±0.16 and 0.33±0.04), and that of bax protein in low dose curcumin group and high dose curcumin group was significantly higher than that of blank control group (P<0.05). The expression level of bcl-2 protein in U87 cells of high dose curcumin group was significantly higher than that of low dose curcumin group, and that of bax protein was significantly higher in low dose curcumin group and high dose curcumin group than that in blank control group (P<0.05). Conclusion Curcumin can inhibit the proliferation and promote the apoptosis of U87 glioma cells by promoting the expression of Caspase-3 and Caspase-8 and altering the expression of bcl-2 and bax. Key words: Curcumin; Glioma; Cysteinyl aspartate-specific protease-3; Cysteinyl aspartate-specific protease-9; B cell lymphoma/leukemia-2; B cell lymphoma/leukemia-2 associated X protein