Abstract: Objective To insvestigate the effects of triptolide on the phosphorylation of epidermal growth factor receptor (EGF-R) and its downstream MEK pathway in HaCaT cells stimulated by epidermal growth factor (EGF).Methods HaCaT cells were cultured with recombinant human EGF (rhEGF)as the stimulating signal.The expression of EGF-R,phosphorylated EGF-R,MEK and phosphorylated kinases was detected by the Western blot technique.Results Triptolide significantly inhibited the expression of phosphorylated EGF-R with the IC₅₀ value of 2.38×10^-10 mol/L.The expression of phosphorylated MEK was also downregulated by triptolide with the IC₅₀ value of 6.03×10^-11 mol/L.In contrast,triptolide had no significant effect on the expression of cellular EGF-R or MEK1/2 in HaCat cells stimulated by rhEGF.Conclusion Triptolide can inhibit the phosphorylation of EGF-R and its downstream MEK kinases induced by EGF signal in HaCaT cells.

Key words: Keratinocytes, Receptor epidermal growth factor, MAP kinase kinase kinases, Triptolide