Figure 2

Quercetin inhibited the activation of c-Met in melanoma cells. (A) Cells were treated with the indicated concentrations of quercetin for 6 h and then stimulated with or without HGF (100 ng/ml) for 10 min. Levels of c-Met and phospho-Met in total lysates were evaluated by immunoblotting. The representative results (upper) and the relative phosphorylation levels (bottom) were shown. The relative levels of phospho-Met were calculated after normalizing the levels of phospho-Met to total c-Met. (B) Cells were grown in serum-free medium overnight before incubation with the indicated concentrations of quercetin for 6 h, after stimulation with or without 100 ng/ml HGF for 10 min, cells were lysed for immunoblotting. The representative results (upper) and the relative phosphorylation levels (bottom) were shown. The relative levels of phospho-Met were calculated after normalizing the levels of phospho-Met to the total c-Met. (C) Quercetin reduced c-Met homo-dimerization. Cells were starved overnight and then treated with indicated concentrations of quercetin for 6 h. After that, these cells were stimulated with or without HGF (100 ng/ml) for 10 min, and then incubated with BS³. Cell lysates were prepared for immunoblotting by using an anti-c-Met antibody. The arrows indicated the dimer (D) and the monomer (M) c-Met. Molecular weights of the marker are shown on the left. The representative results (left) and the relative expression levels of dimer c-Met (right) were shown. The relative levels of dimer c-Met were analyzed after normalizing the levels of dimer c-Met to monomer c-Met. (D) Effect of quercetin on HGF mRNA expression. Cells were treated with indicated concentrations of quercetin for 24 h and then the real-time PCR analysis was performed to detect the mRNA expression levels of HGF. Data were mean ± S.D. from three independent experiments. *P < 0.05, **P < 0.01 and ^## P < 0.01.