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

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 extracellular vesicles (EVs) on melanoma cells to gain insights into EV-mediated interactions between macrophages and tumor cells. Our results demonstrate that M1 EVs reprogram MV3 melanoma cells into a pro-inflammatory state by upregulating the expression and secretion of pro-inflammatory cytokines CXCL8, IL-6 and IL-1B. This M1 EV -induced inflammatory phenotype enhanced melanoma cell invasion, which was suppressed by CXCL8 silencing. Furthermore, M1 EV treatment activated the NF-?B signaling pathway, and its inhibition with the IKK16 inhibitor led to downregulation of inflammation-associated genes. These results suggest that M1 EVs promote tumor-associated inflammation in melanoma through NF-?B signaling, underscoring the pivotal role of EV-mediated macrophage–tumor cell communication in cancer progression. Overall design: RNA-seq was performed on MV3 melanoma cells treated with Ctrl, M0, M1 and M2 EVs for 24 h (n=3). Macrophage-derived EVs were isolated by ultracentrifugation from conditioned media of THP-1 cells polarized to M0, M1 and M2 macrophages for 48 h.