Anthecotulide Sesquiterpene Lactone Exhibits Selective Anticancer Effects in Human Malignant Melanoma Cells by Activating Apoptotic and Autophagic Pathways, S-Phase Cell Cycle Arrest, Caspase Activation, and Inhibition of NF-κB Signalling Pathway

BACKGROUND: We examined the anticancer potential of anthecotulide against SK-MEL-24 malignant melanoma cells. The apoptotic and autophagic effects of anthecotulide were also investigated. MATERIAL/METHODS: The cell viability of SK-MEL-24 human malignant melanoma cells was evaluated by WST-1 assay. Fluorescence microscopy using acridine orange and ethidium bromide staining, as well as Western blot analysis, were used to study apoptotic effects induced by anthecotulide. Autophagy was assessed by Western blot analysis and fluorescence microscopy. Effects of anthecotulide on cell cycle progression were analyzed by flow cytometry. RESULTS: The results revealed that anthecotulide exerts significant growth-inhibitory effects on SK-MEL-24 cells. The IC(50) of anthecotulide against the SK-MEL-24 cells was found to be 10 μM. However, the anticancer effects against the normal cells were minimal (IC50; 100 μM). Investigation of the underlying mechanism revealed that anthecotulide prompts apoptotic cell death of the SK-MEL-24 cells, which was linked with increased expression of Bax and decreased expression of Bcl-2. It also triggered concentration-dependent activation of caspase 3 and 9. Anthecotulide induced autophagy in the SK-MEL-24 cells, which was associated with upregulation of LC3 II and Beclin-1 expression. Anthecotulide also halted the SK-MEL-24 cells at S-phase of the cell cycle and downregulated the expression of Cyclin B1. However, the expression of p27 was upregulated. CONCLUSIONS: These results indicate anthecotulide is a potent lead molecule for the treatment of melanoma. In vivo and other related experiments are warranted to further assess this promising drug candidate.