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Shawn C. Maloney, Emilia Antecka, Andre Nantel, Sheila Smiley, Alison Cameron-Vendrig, Miguel N. Burnier, Jr.; Nicotinamide Alters the Angiogenic Cytokine Profile of RPE Cells. Invest. Ophthalmol. Vis. Sci. 2011;52(14):415.
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© ARVO (1962-2015); The Authors (2016-present)
Nicotinamide (NIC) has been shown to alter expression of some angiogenic proteins. This study aimed to investigate the effects of NIC on ARPE-19 cells as a first step in evaluating this agent as a possible therapeutic candidate in neovascular eye disease.
ARPE-19 cells were treated with 10mM NIC for 48 hours in culture under normoxia or hypoxia (CoCl2). The supernatant from control and NIC conditions was used in an ELISA-based angiogenesis array to evaluate differences in secreted angiogenic proteins. TUNEL staining was performed to assess possible cytotoxicity of NIC and CoCl2. RNA was extracted from harvested cells and was analyzed by microarray. Genes with a 2-fold change or greater were considered significant.
Of the ten angiogenic proteins studied, only four - VEGF, PDGF-BB, ANG-2, and Angiogenin - were detectable in cell supernatant in any of the study conditions. NIC treatment decreased the secretion of all four proteins under normoxia; however, during hypoxia, NIC reduced secretion of VEGF only, while ANG-2 and Angiogenin secretion increased. TUNEL staining demonstrated that neither NIC, CoCl2, or the combination thereof significantly increased cell death compared to the control. Microarray analysis revealed 120 genes downregulated and 48 genes upregulated by NIC during normoxia, while 175 genes were downregulated and 185 upregulated during hypoxia. Only one gene - NOG - was downregulated by NIC under both normoxia and hypoxia and no genes were commonly upregulated. However, 37 of 48 genes that were upregulated by NIC under normoxia were downregulated by NIC under hypoxia. Similarly, 90 of 120 genes downregulated by NIC under normoxia were upregulated by NIC under hypoxia, including IL8.
Our data suggests that NIC can regulate expression and secretion of angiogenic cytokines in ARPE-19 cells. Accordingly, use of NIC may represent a therapeutic approach in AMD to alter angiogenic signaling. Further study of its potential anti-angiogenic effects in neovascular eye disease should consider the differential regulation of some angiogenic cytokines during normoxia and hypoxia.
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