Metastasis is the leading cause of cancer mortality. Cancer cells must adapt to colonize and thrive at the metastatic site. The modulation of the receptive organ microenvironment is a key event in the adaptation process and is partially accomplished at a distance by the primary tumor. Exosomes, a subclass of extracellular vesicles (EVs), are distal mediators of communication that carry genetic and molecular information to neighboring and distant cells. Cancer exosomes have been involved in restructuring metastatic sites to support cancer cell colonization. Researchers from the Universidade do Porto, Portugal discuss the role of exosomes in the metastatic process.
Metastasis organotropism is not entirely explained by the anatomy of the blood and lymphatic circulatory networks. Other factors influence metastatic cells’ ability to seed and prosper in a host organ, including its microenvironment and specific cues originating from the tumor of origin. Exosomes have been proposed to be both short- and long-distance mediators of intercellular communication through the modulation of recipient cells on ligand–receptor interaction and/or cargo release. In addition to cancer exosomes, exosomes derived from other cells of the tumor microenvironment have been described as key players in the various steps of the metastatic cascade. Exosomes derived from the primary tumor influence circulating tumor cells to enhance their tumor self-seeding ability.