Julio B. Daleprane,4,5,8* Tobias Schmid,6 Nathalie Dehne,6 Martina Rudnicki,4 Heidi Menrad,6 Theresa Geis,6 Masaharu Ikegaki,7 Thomas P. Ong,5 Bernhard Bru ̈ne,6 and Dulcineia S. P. Abdalla4
4Department of Clinical and Toxicology Analysis, and 5Department of Food and Experimental Nutrition, Faculty of Pharmaceutical Sciences, University of Sao Paulo, Sao Paulo, Brazil; 6Institute of Biochemistry I, Faculty of Medicine, Goethe-University Frankfurt, Frankfurt, Germany; and 7Department of Pharmacy, Federal University of Alfenas, Alfenas, Brazil
Abstract
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-1 a (HIF1a) 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 HIF1a protein accumulation, which in turn attenuated VEGF gene expression. In addition, RPP reduced the HIF1a protein half-life from ;58 min to 38 min under hypoxic conditions. The reduced HIF1a protein half-life was associated with an increase in the von Hippel-Lindau (pVHL)-dependent proteasomal degradation of HIF1a. RPP (10 mg/L, 4 h) downregulated Cdc42 protein expression. This caused a corresponding increase in pVHL protein levels and a subsequent degradation of HIF1a. In summary, we have elucidated the underlying mechanism for the antiangiogenic action of RPP, which attenuates HIF1a protein accumulation and signaling. J. Nutr. doi: 10.3945/jn.111.150706.
* THESE STATEMENTS HAVE NOT BEEN EVALUATED BY THE FOOD AND DRUG ADMINISTRATION. THIS IS NOT INTENDED TO DIAGNOSE, TREAT CURE OR PREVENT ANY DISEASE.