Angiogenic Potential of 3-Nitro-4-Hydroxy Benzene Arsonic Acid (Roxarsone)

Abstract

BackgroundRoxarsone (3-nitro-4-hydroxy benzene arsonic acid) is an arsenic compound widely used in the poultry industry as a feed additive to prevent coccidiosis, stimulate growth, and to improve tissue pigmentation. Little is known about the potential human health effects from roxarsone released into the environment from chicken waste or from residual compound in chicken products.ObjectiveThe growth potentiation and enhanced tissue pigmentation suggest that low levels of roxarsone exposure may have an angiogenic potential similar to that of inorganic arsenite (AsIII). The goal of this investigation was to test the hypothesis described above using cultured human aortic and lung microvascular endothelial cells in high-content imaging tube-forming assays and begin developing a molecular level understanding of the process.MethodsWe used a three-dimensional Matrigel assay for probing angiogenesis in cultured human endothelial cells, and a polymerase chain reaction (PCR) array to probe the gene changes as a function of roxarsone or AsIII treatment. In addition, we used Western blot analysis for changes in protein concentration and activation.ResultsRoxarsone was found to exhibit a higher angiogenic index than AsIII at lower concentrations. Increased endothelial nitric oxide synthase (eNOS) activity was observed for roxarsone but not for AsIII-induced angiogenesis. However, AsIII caused more rapid and pronounced phosphorylation of eNOS. Quantitative PCR array on select genes revealed that the two compounds have different and often opposite effects on angiogenic gene expression.ConclusionsThe results demonstrate that roxarsone and AsIII promote angiogenic phenotype in human endothelial cells through distinctly different signaling mechanisms.