Exosomes are secreted vesicles which can transmit molecular cargo between cells. Exosomal microRNAs (exomiRs) have drawn much attention in recent years because there is increasing evidence to suggest that loading of microRNAs into exosomes is not a random process. Preclinical studies have identified functional roles for exomiRs in influencing many hallmarks of cancer. Mechanisms underpinning these actions, such as exomiR receptors (“miRceptors”), are now becoming apparent. Even more exciting is the fact that exomiRs are highly suitable candidates for use as non-invasive biomarkers in an era of personalized cancer medicine.
Exosomes: extracellular vesicles with an endosomal origin
Endosomes are packaged into MVBs, which are trafficked either to the cell membrane for secretion (cholesterol-rich) or to lysosomes (cholesterol-deficient) for degradation. MVBs fuse with the cell membrane to release exosomes.