In vitro Anti-angiogenic Activity of Persian Shallot (Allium Hirtifolium) Extract Is Mediated Through Inhibition of Endothelial Cell Proliferation/Migration and Down-regulation of VEGF and MMP Expression

Development of phytotherapies aimed at angiogenesis inhibition, in combination with classical anti-cancer therapies, is among the most intensively studied approaches for treatment of cancer. Epidemiological and animal studies have indicated that consumption of Allium species like shallot is associated with a reduced risk of cancer development. As a continuation of our efforts to study and characterize the effective anti-angiogenic agents from Allium species, here, we investigated the effects of aqueous extract of shallot on critical steps and mediators of in vitro angiogenesis. The anti-proliferation, -migration, and -tubulogenesis properties of the aqueous extract of shallot (at 100 - 1500 µg/ml) were evaluated using three-dimensional capillary tube formation as well as a wound-healing assay in endothelial cell-based experimental systems. In addition, the effect of the extract on vascular endothelial growth factor (VEGF) secretion and matrix metalloproteinase (MMP-2 and -9) expression was assayed using ELISA, gelatin zymography, and RT-PCR techniques. Treatment with the aqueous extract of shallot at ≥ 500 µg/ml concentrations resulted in significant decreases in endothelial cell proliferation, migration, and tubulogenesis. Moreover, the extract caused a dose-related inhibition of VEGF secretion and MMP-2/-9 expression. Taking all the data into account, the current study indicated that shallot – containing potent anti-angiogenic properties - exerts its inhibitory effect mainly through down-regulation of VEGF and MMP-2/-9; essential angiogenic mediators in many malignant and chronic inflammatory diseases.