Abstract
BackgroundEllagic acid (EA), a dietary polyphenolic compound, has been demonstrated to exert anti-angiogenic effect but the detailed mechanism is not yet fully understood. The aim of this study was to investigate whether the zinc chelating activity of EA contributed to its anti-angiogenic effect.Methods and Principal FindingsThe matrix metalloproteinases-2 (MMP-2) activity, a zinc-required reaction, was directly inhibited by EA as examined by gelatin zymography, which was reversed dose-dependently by adding zinc chloride. In addition, EA was demonstrated to inhibit the secretion of MMP-2 from human umbilical vein endothelial cells (HUVECs) as analyzed by Western blot method, which was also reversed by the addition of zinc chloride. Reversion-inducing cysteine-rich protein with Kazal motifs (RECK), known to down-regulate the MMP-2 activity, was induced by EA at both the mRNA and protein levels which was correlated well with the inhibition of MMP-2 activity. Interestingly, zinc chloride could also abolish the increase of EA-induced RECK expression. The anti-angiogenic effect of EA was further confirmed to inhibit matrix-induced tube formation of endothelial cells. The migration of endothelial cells as analyzed by transwell filter assay was suppressed markedly by EA dose-dependently as well. Zinc chloride could reverse these two effects of EA also in a dose-dependent manner. Since magnesium chloride or calcium chloride could not reverse the inhibitory effect of EA, zinc was found to be involved in tube formation and migration of vascular endothelial cells.Conclusions/SignificanceTogether these results demonstrated that the zinc chelation of EA is involved in its anti-angiogenic effects by inhibiting MMP-2 activity, tube formation and cell migration of vascular endothelial cells. The role of zinc was confirmed to be important in the process of angiogenesis.
Highlights
Ellagic acid (EA) is a dietary polyphenol known to be present abundantly in fruits and vegetables [1,2,3]
Since EA is able to complex with zinc ion and matrix metalloproteinases-2 (MMP-2) is a zinc-dependent enzyme, we first examined the effect of EA directly on matrix metalloproteinases (MMPs)-2 activity
We found that the MMP-2 activity was inhibited and this inhibitory effect of EA could be reversed by adding ZnCl2
Summary
Ellagic acid (EA) is a dietary polyphenol known to be present abundantly in fruits and vegetables [1,2,3]. The multiple effects of EA such as antioxidant, anti-proliferative, chemopreventive, and anti-atherogenic properties have been demonstrated in different studies [1,2,3,4,5,6,7,8,9]. Only a few studies regarding the anti-angiogenic effect of ellagic acid have been reported. The more detailed mechanism responsible for the anti-angiogenic effect of EA is still needed to be further explored. Ellagic acid (EA), a dietary polyphenolic compound, has been demonstrated to exert anti-angiogenic effect but the detailed mechanism is not yet fully understood. The aim of this study was to investigate whether the zinc chelating activity of EA contributed to its anti-angiogenic effect
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