Monocyte chemoattractant protein-1–induced angiogenesis is mediated by vascular endothelial growth factor-A

Monocyte chemoattractant protein-1 (MCP-1) has been recognized as an angiogenic chemokine. In the present study, we investigated the detailed mechanism by which MCP-1 induces angiogenesis. We found that MCP-1 up-regulated hypoxia-inducible factor 1α (HIF-1α) gene expression in human aortic endothelial cells (HAECs), which induced vascular endothelial growth factor-A165 (VEGF-A165) expression in the aortic wall and HAECs through activation of p42/44 mitogen-activated protein kinase (MAPK). In vivo angiogenesis assay using chick chorioallantoic membrane (CAM) showed that MCP-1–induced angiogenesis was as potent as that induced by VEGF-A165 and completely inhibited by a VEGF inhibitor, Flt2-11. The inhibition of RhoA small G protein did not affect MCP-1–induced VEGF-A165 production and secretion but completely blocked both MCP-1– and VEGF-A–induced new vessel formation, as determined by CAM assay. These results suggest that MCP-1–induced angiogenesis is composed largely of 2 sequential steps: the induction of VEGF-A gene expression by MCP-1 and the subsequent VEGF-A–induced angiogenesis.