Inhibition of egf receptor tyrosine kinask activity by plant polyphenols

Abstract

It is known that growth factor receptor tyrosine kmases are veiv important to the regulation of cell growth and d i fièrent i at ion In the previous study, we used genistein, an isoflavone and tyrosine kinase inhibitor, to study the relationship between the EGF receptor tyrosine kinase activity and the internalization and degradation of EGF-HGF receptor complexes (Biochcm. Hiophvs. Rc\. ( 'omtmin. 224 .i()l)-.i 17 ( lc)%)) In the present study, the inhibitory effects of 32 plant polvphenols on EGF receptor tyrosine kinase activity were determined I ;sing EC'1. Western blotting, it was found that, in these plant polyphenols, quercetin, genistein, kaempferol, biochanin A, chalcone, 4'-hydroxychalcone. butein, and 2'-hydroxychalcone inhibited EGF receptor tyrosine kinase aetivitv induced by EGF in cultured human hepatoma HepG2 cells The inhibition was dose-dependent. The kinetic studies showed that the inhibition of tyrosine kinase activity of purified EGF; receptor bv these inhibitors v\as different.