Fig. 5

Mechanisms of Exosomal miRNA Regulation of Angiogenesis in Tumor Microenvironments. Exosomal miRNAs taken up by endothelial cells in the tumor microenvironment can affect angiogenesis. For example, in nasopharyngeal carcinoma (NPC), miR-23a-derived exosomes promote angiogenesis by targeting TSGA10 and activating the phosphorylation of p-ERK. In glioma, miR-21 and miR-9 induce angiogenesis by activating the VEGF/p-FLK/VEGFR2 pathway and MYC and OCT4, respectively. In non-small lung cancer, miR-619-5p and miR-142-3p promote angiogenesis by inhibiting RCAN1,4 and PDGFR-β, and p-SMAD2/3, respectively. Similar mechanisms apply to other types of cancer. For instance, in hepatocellular carcinoma (HCC), mesenchymal stem cells (MSCs), myeloid-derived suppressor cells (MDSCs), and ovarian cancer, miRNAs such as miR-210-3p, miR-100, miR-126-a, miR-205, and miR-141-3p promote angiogenesis, while miRNAs derived from hepatic lineage stem cells (HLSC) like miR-15a, miR-181b, miR-874, and miR-320c inhibit angiogenesis. *( +): increase, (−): decrease