Unraveling the role of extracellular vesicle-mediated interleukin-8 signaling in melanoma invasion

Introduction
Metastasis is a critical step in tumor progression and represents the main cause of melanoma-related mortality. This process is sustained by dynamic intercellular communication among heterogeneous tumor cell populations within the tumor microenvironment. Tumor-derived extracellular vesicles (EVs) have emerged as key mediators of this crosstalk, as they shuttle bioactive molecules capable of reprogramming recipient cells. However, the contribution of EVs to the horizontal transfer of metastatic traits within melanoma cell populations remains incompletely understood.

Methods
We investigated the effects of EVs released by aggressive melanoma cell lines (A375M and SM) on poorly invasive A375P cells. EVs were isolated and characterized, and phenotypic as well as functional changes in recipient cells were assessed following EV exposure. Molecular mechanisms were explored by analyzing EV cargo composition, neutralizing IL-8 activity, inhibiting NF-κB signaling, and stimulating cells with recombinant IL-8.

Results
EVs derived from aggressive melanoma cells induced marked phenotypic and functional changes in A375P cells, including elongated morphology, increased migratory and invasive capacity, resistance to anoikis, anchorage-independent growth, enhanced re-adhesion, and increased clonogenic potential. Mechanistically, these effects were driven by IL-8 enrichment in aggressive melanoma-derived EVs. Neutralization of IL-8 or pharmacological inhibition of the NF-κB pathway completely abolished EV-induced phenotypes, whereas stimulation with recombinant IL-8 was sufficient to recapitulate them.

Conclusions
These findings demonstrate that melanoma-derived EVs promote invasive and metastatic traits in recipient cells through activation of the IL-8/NF-κB axis, highlighting this signaling pathway as a potential therapeutic target in advanced melanoma.