Abstract: In this study,the effects of curcumin on proliferation and apoptosis of human hepatoma SMMC-7721 cells were investigated.The possible mechanism of apoptosis was further explored.MTT and cell number assays were used to detect the effect of curcumin on human hepatoma SMMC-7721 cells proliferation.The apoptotic SMMC-7721 cells were examined by flow cytometry.The relative apoptotic protein expressions of Caspase-3,Survivin,Bcl-2 and Bax were detected by RT-PCR and western blot.The possible mechanism of apoptosis was investigated by detecting the phosphorylation of MAPK in SMMC-7721 cells treated with curcumin.MAPK inhibitors were used to further confirm the molecular mechanism of curcumin induced SMMC-7721 cells apoptosis.MTT and cell number assays showed that curcumin inhibited the proliferation of SMMC-7721 cells in a time and dose-dependent manner.Flow cytometry indicated that 40 μmol/L curcumin significantly induced apoptosis of SMMC-7721 cells.RT-PCR and western blot showed that curcumin increased pro-apoptotic protein expression of Caspase-3 and Bax,decreased anti-apoptotic protein expression of Survivin and Bcl-2 in a time-dependent manner.The phosphorylation level of MAPK suggested that curcumin activated JNK and inhibited ERK/P38 MAPK signaling pathways,which mediated modulation of apoptosis-related protein expression and apoptosis of human hepatoma SMMC-7721 cells.Hence,it was concluded that curcumin induced apoptosis through activating JNK and inhibiting ERK/P38 MAPK signaling pathways in human hepatoma SMMC-7721 cells,which involved up-regulating pro-apoptotic protein expression and down-regulating anti-apoptotic protein expression.

Key words: curcumin, human hepatoma cells, apoptosis-related protein, MAPK signaling pathway