Abstract
Astragaloside IV is the major active constituent of Astragalus membranaceus, which has been widely used for the treatment of cardiovascular diseases in China. The aim of this study was to determine the angiogenic effect of astragaloside IV and its underlying mechanism. We used the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide assay, Western blotting, real-time polymerase chain reaction, and immunofluorescence to detect the effect of astragaloside IV on proliferation of human umbilical vein endothelial cells (HUVECs), the phospho-Akt protein level, hypoxia-inducible factor-1α (HIF-1α) accumulation, vascular endothelial growth factor mRNA expression, and applied cell migration, tube formation, and chick chorioallantoic membrane assays to study the angiogenic effect of astragaloside IV. Results indicate that astragaloside IV promoted cell proliferation and stimulated HIF-1α accumulation during hypoxia. Mechanism studies revealed that astragaloside IV did not affect the degradation of HIF-1α protein or the level of HIF-1α mRNA. In contrast, astragaloside IV apparently activated the phosphatidylinositol 3-kinase (PI3K)/Akt pathway, which regulates HIF-1α protein synthesis. Moreover, astragaloside IV also stimulated cell migration, increased tube formation, and promoted angiogenesis in the chick chorioallantoic membrane assay. All angiogenic effects of astragaloside IV were reversed by the 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.
Footnotes
This work was supported by the National Natural Science Foundation of China [Grants 30830121, 30801461]; the National Key Scientific and Technological Project of China [Grant 2009ZX09311-002]; and the International S&T Cooperation Project of China [Grant 2009DFB30510].
Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
doi:10.1124/jpet.111.180992.
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ABBREVIATIONS:
- HIF-1α
- hypoxia-inducible factor-1α
- VEGF
- vascular endothelial growth factor
- HUVEC
- human umbilical vein endothelial cell
- PI3K
- phosphatidylinositol 3-kinase
- DMSO
- dimethyl sulfoxide
- M199
- medium 199
- FBS
- fetal bovine serum
- MTT
- 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide
- HC
- hypoxia control
- NC
- normal control
- PBS
- phosphate-buffered saline
- PCR
- polymerase chain reaction
- LY294002
- 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one
- CAM
- chick chorioallantoic membrane
- MG132
- N-benzoyloxycarbonyl (Z)-Leu-Leu-leucinal.
- Received February 25, 2011.
- Accepted May 13, 2011.
- Copyright © 2011 by The American Society for Pharmacology and Experimental Therapeutics
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