Extracellular vesicles derived from pro-inflammatory M1 macrophages induce an inflammatory and invasive phenotype in melanoma cells.

BACKGROUND: Melanoma progression and metastasis depend on intercellular communication within the tumor microenvironment (TME), where extracellular vesicles (EVs) have emerged as essential mediators through the transfer of molecular cargo. In melanoma, macrophages are enriched in the TME, and their abundance and infiltration into the tumor area are associated with poor prognosis. In this study, we examined the effects of pro-inflammatory M1 and immunosuppressive M2 macrophage-derived EVs on melanoma cells to gain insights into EV-mediated interactions between macrophages and tumor cells. METHODS: Macrophage-derived EVs were isolated by ultracentrifugation from the conditioned media of THP-1 cells polarized to M0, M1 and M2 macrophages. The cytokine content of M0 and M1 EVs was analyzed using a cytokine array. MV3 and COLO800 melanoma cells were treated with EVs to investigate their impact on gene expression using RNA-seq and qPCR. The functional effects of EVs on melanoma cells were assessed with invasion and spheroid assays, confocal imaging and western blotting. RESULTS: Our results demonstrate that M1 EVs reprogrammed MV3 melanoma cells into a pro-inflammatory state by upregulating the gene expression and secretion of the pro-inflammatory cytokines CXCL8, IL-6 and IL-1β. This M1 EV -induced inflammatory phenotype enhanced melanoma cell invasion, which was suppressed by CXCL8 silencing. Furthermore, M1 EV treatment activated the NF-ĸB signaling pathway, and its inhibition with IKK16 inhibitor led to the downregulation of inflammation-associated genes. CONCLUSIONS: Our findings suggest that M1 EVs promote tumor-associated inflammation in melanoma cells through NF-ĸB signaling. This underscores the pivotal role of EV-mediated macrophage-tumor cell communication in cancer progression.