Figure 1.

The biogenesis, Structure, and functions of the exosome. Exosomes are 50-100 nm nanoscale vesicles with a lipid bilayer membrane. They can carry many essential molecules like proteins, mRNA, miRNA, lipids, and enzymes. Distinct proteins are shown in the figure, such as CD1, MHC I and II, Rab proteins, Annexins, ABC transporters, and signaling transduction-related proteins. Early endosomes are formed by the fusion of primary endocytic vesicles. MVBs fuse with the plasma membrane through the SNARE complex and release their contents called exosomes from the ILVs into the extracellular space. The contents of exosomes can be transferred from the cells to target cells in a local environment or at a distant site in the tumor environment. Exosomes greatly influence a few pathways, such as tumor microenvironment remodeling, signal transduction, tumor angiogenesis and metastasis, immune regulation, and chemotherapy resistance.