Torch ginger (Etlingera elatior, EE) is a ginger plant that found in Southeast Asia. Previous study showed its flowers and leaves composed of several flavonoids with anti-cancer activity. This study aims to investigate the mechanism of EE extract on cell death induction in melanoma cells.
To carry out this study, the cytotoxic effect of EE extract was performed using MTT assay. Nuclear morphological change and loss of mitochondrial membrane potential were observed using Hoechst 33,342 and JC-1 staining. Flow cytometry using Annexin V/PI double staining assessed apoptosis, necrosis and viability. Caspase activity was detected by caspase activity kits. The expression of Bcl-2 family proteins, ERK and Akt signaling pathways were examined by Western blot analysis.
The treatment of EE extract resulted in a dose- and time-dependent reduction in cell viability in B16 cells. It also induced nuclear condensation, phosphatidylserine exposure, and loss of mitochondrial membrane potential, which are markers of apoptosis. Furthermore, the expression of Bim was increased instead of Bax and Bcl-2. The results also showed caspase-independent activity and the down-regulation of ERK and Akt signaling pathway.
The results suggest that EE extract induced caspase-independent cell death via down-regulation of ERK and Akt pathways in B16 cells. This may be beneficial as a chemopreventive or chemotherapeutic agent in melanoma treatment.