Figure 1.

Schematic illustration of main characteristics of tumor-derived exosomes (TEXs). TEXs are membrane nanovesicles (30–140 nm) secreted by cancer cells. They carry specific tumor-derived integrins on their surfaces, which preferentially interact with certain endothelial cells. Once bound to the receptor cells, TEXs can deliver tumor-derived genetic molecules such as miRNAs and reprogram the recipient cells in the favor of cancer metastasis. TEXs also carry various immunosuppressive surface proteins such as PD-L1 that can directly interact with cytotoxic T-cells through PD-1/PD-L1 interaction locally and systemically, and inhibit T-cell anticancer function.