Extracellular vesicles (EVs) are heterogeneous membranous vesicles released from many cell types into the extracellular space. EVs containing microRNAs (EV-miRNAs) are selectively secreted in response to various pathological and physiological conditions, serving as novel mediators for intercellular crosstalk. EV-miRNAs play significant roles in diverse physiologies and diseases. Especially, accumulating evidence supports the role of tumor-derived EV-miRNAs in tumorigenesis. EV-miRNAs mediate the communications between tumor cells and non-malignant cells in the tumor microenvironment (TME), thereby affecting angiogenesis, invasion, metastasis, drug resistance and immunity evasion. In this review, we summarize the evidence on the selectivity of miRNAs secretion and underlying mechanisms. We also describe the pathological functions of tumor-derived EV-miRNAs on tumorigenesis and secretion. Then, we discuss the potential applications of EV-miRNAs as biomarkers in cancer diagnosis and prognosis.
extracellular vesicles; extracellular miRNAs; miRNAs secretion mechanisms; tumor microenvironment; cancer