Suppression of Hypoxia-Inducible Factor-1α Contributes to the Antiangiogenic Activity of Red Propolis Polyphenols in Human Endothelial Cells

• Published in: The Journal of nutrition Vol. 142; no. 3; pp. 441 - 447
• Main Authors: DALEPRANE, Julio B, SCHMID, Tobias, DEHNE, Nathalie, RUDNICKI, Martina, MENRAD, Heidi, GEIS, Theresa, IKEGAKI, Masaharu, ONG, Thomas P, BRÜNE, Bernhard, ABDALLA, Dulcineia S. P
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Society for Nutrition 01.03.2012
• Subjects: Angiogenesis Inhibitors - chemistry; Angiogenesis Inhibitors - pharmacology; Animals; Biological and medical sciences; Cell Differentiation - drug effects; Cell Line; Cell Movement - drug effects; Chick Embryo; Endothelial Cells - cytology; Endothelial Cells - drug effects; Endothelial Cells - physiology; Feeding. Feeding behavior; Fundamental and applied biological sciences. Psychology; Gene Expression - drug effects; Humans; Hypoxia-Inducible Factor 1, alpha Subunit - antagonists & inhibitors; Hypoxia-Inducible Factor 1, alpha Subunit - metabolism; Male; Neovascularization, Physiologic - drug effects; Polyphenols - chemistry; Polyphenols - pharmacology; Propolis - chemistry; Protein Stability - drug effects; Rats; Rats, Wistar; RNA, Messenger - genetics; RNA, Messenger - metabolism; Vascular Endothelial Growth Factor A - genetics; Vascular Endothelial Growth Factor A - metabolism; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Von Hippel-Lindau Tumor Suppressor Protein - metabolism; Micronutrient; Human; Red; Oxygen; Endothelial cell; Polyphenol; Nutrition; Environmental factor; Hypoxia; Proanthocyanidin; Antiangiogenic agent
• DOI: 10.3945/jn.111.150706
• ISSN: 0022-3166

Polyphenol-enriched fractions from natural sources have been proposed to interfere with angiogenesis in pathological conditions. We recently reported that red propolis polyphenols (RPP) exert antiangiogenic activity. However, molecular mechanisms of this activity remain unclear. Here, we aimed at characterizing molecular mechanisms to explain the impact of RPP on endothelial cells' (EC) physiology. We used in vitro and ex and in vivo models to test the hypothesis that RPP inhibit angiogenesis by affecting hypoxia-inducible factor-1α (HIF1α) stabilization in EC. RPP (10 mg/L) affected angiogenesis by reducing migration and sprouting of EC, attenuated the formation of new blood vessels, and decreased the differentiation of embryonic stem cells into CD31-positive cells. Moreover, RPP (10 mg/L) inhibited hypoxia- or dimethyloxallylglycine-induced mRNA and protein expression of the crucial angiogenesis promoter vascular endothelial growth factor (VEGF) in a time-dependent manner. Under hypoxic conditions, RPP at 10 mg/L, supplied for 1-4 h, decreased HIF1α protein accumulation, which in turn attenuated VEGF gene expression. In addition, RPP reduced the HIF1α protein half-life from ~58 min to 38 min under hypoxic conditions. The reduced HIF1α protein half-life was associated with an increase in the von Hippel-Lindau (pVHL)-dependent proteasomal degradation of HIF1α. RPP (10 mg/L, 4 h) downregulated Cdc42 protein expression. This caused a corresponding increase in pVHL protein levels and a subsequent degradation of HIF1α. In summary, we have elucidated the underlying mechanism for the antiangiogenic action of RPP, which attenuates HIF1α protein accumulation and signaling.