Quercetin-3-methyl ether suppresses proliferation of mouse epidermal JB6 p+ cells by targeting ERKs

Chemoprevention has been acknowledged as an important and practical strategy for the management of skin cancer. Quercetin-3-methyl ether, a naturally occurring compound present in various plants, has potent anticancer-promoting activity. We identified this compound by in silico virtual screening of the Traditional Chinese Medicine Database using extracellular signal-regulated kinase 2 (ERK2) as the target protein. Here, we showed that quercetin-3-methyl ether inhibited proliferation of mouse skin epidermal JB6 P+ cells in a dose- and time-dependent manner by inducing cell cycle G₂-M phase accumulation. It also suppressed 12-O-tetradecanoylphorbol-13-acetate-induced neoplastic cell transformation in a dose-dependent manner. Its inhibitory effect was greater than quercetin. The activation of activator protein-1 was dose-dependently suppressed by quercetin-3-methyl ether treatment. Western blot and kinase assay data revealed that quercetin-3-methyl ether inhibited ERKs kinase activity and attenuated phosphorylation of ERKs. Pull-down assays revealed that quercetin-3-methyl ether directly binds with ERKs. Furthermore, a loss-of-function ERK2 mutation inhibited the effectiveness of the quercetin-3-methyl ether. Overall, these results indicated that quercetin-3-methyl ether exerts potent chemopreventive activity by targeting ERKs.