Anti-Angiogenesis Efficacy of the Novel NF-B and Oxidative Stress Inhibitor, OT-551

Abstract

Purpose: : Recent reports have suggested the importance of mediators in addition to vascular endothelial growth factor (VEGF) in ocular angiogenesis-associated disorder. Hence, the purpose of this investigation was to evaluate the anti-angiogenesis efficacy of OT-551, a small molecule that inhibits nuclear factor-ΚB (NF-ΚB) and oxidative stress pathways, on angiogenesis in the chick chorioallantoic membrane (CAM) model as well as its efficacy on NF-ΚB associated pro-inflammatory pathways.

Methods: : OT-551 was tested for inhibition of various pro-angiogenesis stimuli, including oxidative stress (H₂O₂, lipid hydroperoxide), basic fibroblast growth factor (bFGF), VEGF, angiotensin II, bradykinin, and lipopolysaccharide (LPS). OT-551 was also tested in combination with bevacizumab or ranibizumab in inhibiting VEGF-induced angiogenesis in the CAM model. Additionally, NF-ΚB activation and oxidative stress pathways were evaluated using microarray, RT-PCR, Western blots, gel shift, and membrane lipid peroxidation assays ; LPS-induced, NF-ΚB-dependent upregulation of chemokines and cytokines was determined in vitro in human blood as well as in vivo in a mouse model treated with different doses OT-551.

Results: : OT-551 effectively inhibited angiogenesis-induced by various stimuli in CAM model. Furthermore, enhanced anti-angiogenesis efficacy was demonstrated when OT-551 was utilized in combination with bevacizumab or ranibizumab in inhibiting VEGF-induced angiogenesis in the CAM model. OT-551 demonstrated effective inhibition of LPS-induced NF-ΚB activation, nuclear translocation of p50/p65, degradation of IKBα, without any effect on nuclear p50/p65 DNA binding. OT-551 effectively inhibited LPS-mediated TNF-α production in vitro by human blood cells with an IC₅₀ of 9.2 µM. Similarly in mice, in a dose-dependent manner, OT-551 effectively inhibited up-regulation of chemokines and cytokines, without any effect on basal/constitutive levels of cytokines(e.g. TNF-α). Additionally, OT-551 inhibited membrane lipid peroxidation (80-90% inhibition at 1.0 -3.0 µM). Microarray results demonstrated effective inhibition of NADH oxidase in the human monocytic cell line.

Conclusions: : These results indicated a broad spectrum of anti-angiogenesis efficacy of OT-551 against various mediators. The compound enhanced the anti-angiogenesis efficacy of bevacizumab and ranibizumab. These properties of OT-551 are likely related to its ability to inhibit NF-ΚB activation and cellular oxidative stress pathways.

Keywords: inflammation • growth factors/growth factor receptors • antioxidants