Abstract: To investigate the inhibitory effect of chrysin from traditional Chinese medicine propolis capsule on sphere forming capability of liver cancer stem-like cells derived from human hepatocellular carcinoma SMMC-7721 cell line and its mechanism.Suspension culture with the stem cell-condition medium was used to obtain the third generation spheroids derived from SMMC-7721 cell line defined as SFCs.Sphere formation assay was used to evaluate the effects of chrysin on sphere forming rate of SFCs.Western blot was used to analyze the expression levels of CD133,CD44,CK2α and Gli1 proteins in SFCs treated with chrysin.CK2αsiRNA transfection was employed to approach the mechanism of chrysin action.The result showed that chrysin reduced the sphere forming rate and down-regulated expressions of CD133,CD44,CK2α and Gli1 proteins of SFCs.Compared with SFCs transfected with scrambled control siRNA,a decrease of CK2α and Gli1 protein expression level in SFCs transfected with CK2αsiRNA was observed.In addition,CK2αsiRNA transfection cooperatively enhanced chrysin down-regulated the expression of CK2α and Gli1 proteins in SFCs.It was showed that chrysin inhibited the sphere forming capability of SFCs may down-regulate CK2α expression through blocking Hedgehog signaling.

Key words: chrysin, hepatocellular carcinoma, cancer stem cell, Hedgehog signaling