Figure 3.

Tumor-derived exosomes (TEXs) promote metastasis by promoting vasculature disruption. Exosomes from metastatic cancer cells contain specific miRNAs, which cause endothelial cells to reduce their expression of important tight-junction proteins like ZO-1, cadherin, and P120. TEXs from the primary tumors leak into the bloodstream and travel to the metastatic sites. Upon arrival to the metastatic sites, they get taken in by endothelial cells there, down-regulate the expression of tight-junction proteins, and hence destroy vascular integrity. The destruction of vascular integrity facilitates metastasis.