119 | Insights into interleukin-8–dependent extracellular vesicle-mediated communication in melanoma

Gaia Giannitti¹, Kinga Kamińska^2|3, Sara Marchesi¹, Riccardo Garavaglia¹, Ivan Preosto¹, Małgorzata Grzesiak², Fabrizio Fontana¹ | ¹Department of Pharmacological and Biomolecular Sciences "Rodolfo Paoletti", University of Milan, Italy; ²Department of Endocrinology, Institute of Zoology and Biomedical Research, Faculty of Biology, Jagiellonian University, Krakow, Poland; ³Department of Animal Biotechnology, University of Agriculture in Krakow, Poland.

Metastasis is a key step in tumor progression, sustained by intercellular communication among heterogeneous tumor cell populations. Tumor-derived extracellular vesicles (EVs) have emerged as important mediators of this crosstalk by transferring bioactive molecules between cells. Here, we investigated the effects of EVs released by aggressive melanoma cell lines (A375M and SM) on the less invasive A375P cells. EV exposure induced profound phenotypic changes, including elongated morphology, enhanced migration and invasion, resistance to anoikis, and anchorage-independent growth. EV-treated cells also displayed accelerated re-adhesion and increased clonogenic capacity, indicative of enhanced metastatic potential. Mechanistically, we identified interleukin-8 (IL-8) enrichment in aggressive melanoma-derived EVs as a key driver of these effects. Neutralization of IL-8 or pharmacological inhibition of NF-κB signaling abrogated EV-induced phenotypes, while recombinant IL-8 recapitulated them. Collectively, these data indicate that melanoma-derived EVs promote invasive and metastatic traits in recipient cells through activation of the IL-8/NF-κB axis, suggesting this pathway as a potential therapeutic target in advanced melanoma.