Antitumor and apoptotic effects of quercetin on human melanoma cells involving JNK/P38 MAPK signaling activation.

In this study, we investigated whether Quercetin has anti-cancer effects on A375SM and A375P human melanoma cells. Cell viability was assessed using an MTT assay. The proliferation of melanoma cells was measured by a wound-healing assay. Quercetin significantly decreased viability and proliferation of A375SM cells in a concentration-dependent manner. However, quercetin had no effect on A375P cells. DAPI staining showed increased chromatin condensation in a concentration-dependent manner, indicating apoptosis. Flow cytometric analysis indicated that quercetin suppressed the viability of A375SM cells by inducing apoptosis. Expression of quercetin-induced apoptosis proteins was investigated by Western blot analysis. Quercetin increased the expression of Bax, phospho-JNK, phospho-p38 and phospho-ERK1/2, cleaved poly-ADP ribose polymerase and decreased Bcl-2 in a concentration-dependent manner. We also investigated the in vivo tumor-growth inhibitory effect of quercetin. Quercetin (at 50 and 100 mg/kg) significantly decreased the A375SM tumor volume compared to the control group and increased apoptosis as assessed by the TUNEL assay. Immunohistochemistry staining revealed that the level of phosphor-JNK and phosphor-p38 increased in the quercetin-treated mice. These results indicate that quercetin inhibited the growth of A375SM melanoma cells through apoptosis and thus can be regarded as a new and effective chemo-preventive or therapeutic agent.