Purpose: The aim of this study was to evaluate the anti-angiogenic properties of soy isoflavones using two breast cancer cell lines, by measuring the concentration of 30 cytokines involved in angiogenesis using a multiplex glass slide ELISA-based array.
Methods: Estrogen-dependent MCF-7 cells and estrogen-independent MDA-MB-231 cells were exposed to genistein (Gen), daidzein (Dai) and a soy seed extract (Ext) for 72 hrs, at selected concentration levels. The conditioned medium was analyzed using a glass slide, multiplex sandwich ELISA-based platform with fluorescent detection which allowed the identification and the quantification of 30 angiogenesis-related cytokines.
Results: In MCF-7 cells, low, stimulatory concentrations of test compounds determined the increase of CXCL16 and VEGF-A level. Gen induced the greatest effect, with 1.5-fold change compared to control. When MDA-MB-231 cells were exposed to inhibitory concentrations, all test compounds determined a reduction of CXCL16 and VEGF-A level with approximately 30%.
Conclusions: Soluble CXCL16 and VEGF-A are two promoters of angiogenesis and metastasis in breast cancer. The stimulation of these two angiogenesis-related cytokines could represent one of the mechanisms explaining the proliferative effects of low isoflavone doses in estrogen-dependent cells. In estrogen-independent cells, soy isoflavones inhibited their secretion, demonstrating promising anti-angiogenic properties.