Nitidine chloride efficiently induces autophagy and apoptosis in melanoma cells via AMPK-mTOR signaling pathway.

Nitidine chloride (NC) has displayed anti-tumor effects in various types of cancer. However, the role of NC in human melanoma is largely unknown. This study aimed to investigate the effects of NC on melanoma cancer cells A375 and WM35 by MTT assay. Apoptosis was measured by detecting caspase-3 protein expression level and its activity. Autophagy was measured by TEM image, immunostaining and immunoblotting assays. MTT assays showed that NC significantly blocks melanoma cells proliferation. Immunoblotting and caspase-3 activity assays showed that NC inhibited melanoma cells proliferation by inducing cell apoptosis. TEM, immunostaining and immunoblotting assays showed that NC also triggers melanoma cells autophagy and activation of the AMPK-mTOR pathway, which plays an important role in autophagy initiation. Finally, we found that blocking autophagy by 3-MA or AMPK pathway inhibitor greatly enhanced NC-induced apoptosis and cell death, indicating that NC-induced autophagy may have a cytoprotective effect in melanoma cells. Together, these results suggested that NC has strong anti-tumor effects on melanoma cells.