Tumor-derived extracellular vesicles in breast cancer: From bench to bedside

Tumor-derived extracellular vesicles (TEVs) released from various tumor cell types comprise endosome-derived exosomes and microvesicles (MVs), which originate from plasma membrane budding. TEVs incorporate a myriad of biomolecules such as proteins, DNAs, metabolites and microRNAs, which can be transferred from cell-to-cell. Besides their role in the disposal of biomolecules, TEVs serve to orchestrate fundamental processes of normal and malignant development, including breast cancer (BC). As such, TEVs are important constituents of the tumor microenvironment (TME) that act as communication shuttles through transduction of encapsulated molecular cargos from a parent to a recipient cell and through direct interaction with target cells. Emerging evidence suggests that TEVs support BC development and disease progression by fostering invasion, angiogenesis, pre-metastatic niche preparation, escape from immune surveillance, and induction of resistance to treatment. Although there is a long way to go in order to translate the current knowledge into actual clinical applications, TEVs represent promising candidates for diagnostic biomarkers, therapeutic carriers and targets. In the present review, we will summarize the current knowledge on TEVs in BC.