Extracellular vesicle transfer of cancer pathogenic components.

Extracellular vesicles (EV), known as exosomes and microvesicles, serve as versatile intercellular communication vehicles. Increasing evidence has shown that cancer cell-derived EV carry pathogenic components, such as proteins, messenger RNA (mRNA), microRNA (miRNA), DNA, lipids and transcriptional factors, that can mediate paracrine signaling in the tumor microenvironment. These data suggest that EV transfer of cancer pathogenic components enable long-distance crosstalk between cancer cells and distant organs, resulting in the promotion of the initial steps for pre-metastatic niche formation. Understanding the metastatic mechanisms through EV transfer may open up a new avenue for cancer therapeutic strategies. Furthermore, the circulating EV have also been of interest as a source for liquid biopsies. EV in body fluids provide a reliable source of miRNA and proteins for cancer biomarkers. The tumor-specific components in EV effectively provide various messages on the physiological and pathological status of cancer patients. Although many researchers are searching for EV biomarkers using miRNA microarrays and proteome analyses, the detection technology for circulating EV in body fluids has not yet reached the point of clinical application. In this review, we summarize recent findings regarding EV function, specifically in metastasis through the transfer of cancer pathogenic components. Furthermore, we highlight the potential of using circulating EV for cancer diagnosis.