Melanoma-derived exosomes: Versatile extracellular vesicles for diagnosis, metastasis, immune modulation, and treatment of melanoma

Malignant melanoma is one of the most aggressive human neoplasms responsible for the majority of skin cancer-related deaths in its advanced stages. Achieving a thorough knowledge of reliable tumor-originated biomarkers and molecular mechanisms can provide many practical approaches and guide the way towards the design of rational curative therapies to improve the survival rate of patients. Cancer cells, including melanoma cells, release high amounts of a broad family of nanovesicles, containing different biochemical messages. Exosomes are a type of extracellular vesicles (EVs) that are generated by different cell populations and participate in the intercellular communication of surrounding and distant cells/tissues. Exosome cargo consists of several biologically active proteins and genomic components. Tumor cells tend to release exosomes throughout the tumor microenvironment, which affects the biological performance of recipient cells. Recent evidence provides new perspective in melanoma management, showing that melanoma-derived exosomes (MEXs) may represent a valuable tool for melanoma diagnosis and treatment. This review presents a summary of the potential role of MEXs in the early diagnosis of melanoma. More importantly, we also discuss the capacity of MEXs in reproducing numerous tumor-related functions required for angiogenesis, immune system modulation, induction of migration and metastatic spread, tumor chemotherapy resistance, and melanoma tumor progression and survival. Considering the advent of novel bioengineering and immunotherapy approaches, natural exosomes can be exerted as nanocarriers and cancer vaccines to facilitate the conduction of more efficient cancer treatment.