Exosomes and extracellular vesicles: Rethinking the essential values in cancer biology

Extracellular vesicles (EVs) such as exosomes are released by all living cells and contain diverse bioactive molecules, including nucleic acids, proteins, lipids, and metabolites. Accumulating evidence of EV-related functions has revealed that these tiny vesicles can mediate specific cell-to-cell communication. Within the tumor microenvironment, diverse cells are actively interacting with their surroundings via EVs facilitating tumor malignancy by regulating malignant cascades including angiogenesis, immune modulation, and metastasis. This review summarizes the recent studies of fundamental understandings of EVs from the aspect of EV heterogeneity and highlights the role of EVs in the various steps from oncogenic to metastatic processes. The recognition of EV subtypes is necessary to identify which pathways can be affected by EVs and which subtypes can be targeted in therapeutic approaches or liquid biopsies.