Synergistic inhibitory effects of transplatin and β-hydroxyisovalerylshikon on carcinoma A431 cells involve epidermal growth factor receptor

Treatment of human epidermoid carcinoma A431 cells with transplatin (trans-DDP) and β-hydroxyisovalerylshikon (β-HIVS) together had a strong inhibitory effect on A431 cells. By contrast, trans-DDP and β-HIVS by themselves, at the same respective concentrations, had practically no effect. The tyrosine kinase activities of v-Src and epidermal growth factor (EGFR) were inhibited by each of the two agents alone and strongly inhibited by combination. The observed synergistic inhibitory effect on the growth of A431 cells might have resulted from the inhibition of EGFR by trans-DDP, as well as by β-HIVS.