C6 ceramide potentiates curcumin-induced cell death and apoptosis in melanoma cell lines in vitro

Abstract

The majority of metastatic melanomas are resistant to diverse chemotherapeutic agents, and long-term survival for patients with melanoma who have metastatic disease is dismal. Consequently, the search for novel anti-melanoma agents is urgent. Here, we evaluate the potential effects of C6 ceramide to sensitize melanoma cell lines (B16 and WM-115 cells) to curcumin-induced cell death. MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay was used to test melanoma cell viability in vitro. Hoechst 33342 fluorescence and Histone DNA ELISA was used to evaluate melanoma cell apoptosis. Apoptosis-associated proteins in melanoma cells after treatments were measured by Western blot. C6 ceramide promotes curcumin-induced cell death and apoptosis in B16 and WM-115 melanoma cell lines. Curcumin itself promotes pro-apoptosis protein Caspase 3 and Caspase 9 cleavage and anti-apoptosis protein Bcl-XL and X-IAP degradation, and combination of C6 ceramide with curcumin dramatically enhances it. Caspase inhibitors largely inhibit C6-ceramide plus curcumin induced cell death and apoptosis. We suggest that C6 ceramide sensitizes melanoma cell to curcumin induced cell death and apoptosis in vitro, which is due to, at least in part, the augment of mitochondria apoptosis pathway. Combining C6 ceramide with traditional chemotherapy drugs such as curcumin may have potential to be used as a new therapeutic intervention against melanoma.