Astragaloside IV is the major active constituent of Astragalus membranaceus, which has been widely used for the treatment of cardiovascular diseases in China. This study aims to determine the angiogenic effect of astragaloside IV and its underlying mechanism. We employed 3-(4,5-dimeth-ylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay, western blotting, real-time PCR and immunofluorescence to detect the effect of astragaloside IV on proliferation of human umbilical vein endothelial cells (HUVECs), phospho-Akt protein level, hypoxia-inducible factor-1α (HIF-1αaccumulation, vascular endothelial growth factor (VEGF) mRNA expression, and applied cell migration, tube formation and chick chorioallantoic membrane (CAM) assays to study the angiogenic effect of astragaloside IV. Results indicate that astragaloside IV promoted cell proliferation and stimulated HIF-1αaccumulation during hypoxia. Mechanism studies revealed that astragaloside IV did not affect the degradation of HIF-1α protein or the level of HIF-1α mRNA. By contrast, astragaloside IV apparently activated the PI3K/Akt pathway, which regulates HIF-1α protein synthesis. Moreover, astragaloside IV also stimulated cell migration, increased tube formation and promoted angiogenesis in chick chorioallantoic membrane assay. All angiogenic effects of astragaloside IV were reversed by PI3K inhibitor. Taken together, our data collectively reveal that astragaloside IV is a novel regulator of HIF-1α and angiogenesis through the PI3K/Akt pathway in HUVECs that are exposed to hypoxia.
- Received February 25, 2011.
- Revision received May 13, 2011.
- Accepted May 13, 2011.
- The American Society for Pharmacology and Experimental Therapeutics