Suppression of hypoxia-inducible factor-1alpha contributes to the antiangiogenic activity of red propolis polyphenols in human endothelial cells.

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Daleprane JB, Schmid T, Dehne N, Rudnicki M, Menrad H, Geis T, Ikegaki M, Ong TP, Brune B, Abdalla DS

Suppression of hypoxia-inducible factor-1alpha contributes to the antiangiogenic activity of red propolis polyphenols in human endothelial cells.

J Nutr. 2012 Mar;142(3):441-7. doi: 10.3945/jn.111.150706. Epub 2012 Jan 25.

PubMed ID
22279137 [ View in PubMed
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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-1alpha (HIF1alpha) 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 HIF1alpha protein accumulation, which in turn attenuated VEGF gene expression. In addition, RPP reduced the HIF1alpha protein half-life from ~58 min to 38 min under hypoxic conditions. The reduced HIF1alpha protein half-life was associated with an increase in the von Hippel-Lindau (pVHL)-dependent proteasomal degradation of HIF1alpha. RPP (10 mg/L, 4 h) downregulated Cdc42 protein expression. This caused a corresponding increase in pVHL protein levels and a subsequent degradation of HIF1alpha. In summary, we have elucidated the underlying mechanism for the antiangiogenic action of RPP, which attenuates HIF1alpha protein accumulation and signaling.