Interplay between autophagy and p38 MAPK during salinomycin-induced cell death in cisplatin-resistant melanoma

Melanoma, a highly aggressive skin cancer, often develops resistance to chemotherapies like Cisplatin (CDDP), leading to treatment failure. This study investigates the potential of Salinomycin, an antibiotic known for targeting cancer stem cells and modulating autophagy, in overcoming CDDP resistance. Notably, there is a lack of consensus on the role of Salinomycin-induced autophagy in cell survival or death. In our study, we used several pharmacological inhibitors to extend our understanding of Salinomycin-induced autophagy and its interactions with regulatory proteins, including the anticancer mechanism in cisplatin-resistant melanoma. Our findings reveal that Salinomycin increases expression of autophagy proteins through ER stress-mediated calcium release and p38 MAPK activation; however, inhibiting autophagy using chloroquine or 3-methyladenine increased Salinomycin’s cytotoxic effects. Further analysis showed that, at later stages, lysosomal damage compromises autophagy flux, leading to cytoplasmic vacuole formation. The size and quantity of these vacuoles are regulated by the p38 MAPK pathway, and inhibition of p38 or calpain enhances their formation. Our results highlight the complex relationship between autophagy, ER stress, and MAPK signaling in melanoma cells treated with Salinomycin, offering insights into its potential use as an adjuvant therapy for treating both CDDP-sensitive and -resistant melanoma.