Inhibitory Effect of Kaempferol on Protein Kinase CK2 in vitro and in HL-60 Cells
Xiao Lin · Zhongguo shengwu huaxue yu fenzi shengwu xuebao · 2006
To investigate the inhibitory effects of kaempferol on protein kinase CK2 in vitro and in HL-60 cells,the effect of recombinant human CK2 holoenzyme activity and cellular CK2 activity by kaempferol were assayed by detecting incorporation of [γ-32P]ATP into the substrate.The mRNA expression of CK2α,α' and β subunits were detected by multiplex RT-PCR.CK2 kinetic analysis was carried out by using the Lineweaver-Burk plot.Kaempferol was shown to inhibit strongly the activity of protein kinase CK2 in vitro(IC_ 50 =1.88 μmol/L)and in HL-60 cells.Intracellular CK2 activity assay showed that kaempferol was more effective than the positive control 4Br-2-azabenzimidazole(TBB).In addition,CK2α,α' and β mRNA level was not changed fundamentally during treatment for 2 hours with kaempferol.Kinetic studies of kaempferol on recombinant human CK2 showed that the inhibition was noncompetitive with ATP(K_i = 1.14 μmol/L)and casein(K_i = 1.03 μmol/L).These results indicated that kaempferol was an effective inhibitor of protein kinase CK2,which is assumed to interfere the combination of CK2 and ATP or its substrates.