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Bo Tian, Haijiang Lin, Daniel E. Maidana, Bernard Dib, John B Miller, Peggy Bouzika, Joan W Miller, Demetrios Vavvas; Effect of MiR-17* on oxidative damage in human retinal epithelial cells. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):811.
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© ARVO (1962-2015); The Authors (2016-present)
Oxidative stress has been shown to contribute to the development of age-related macular degeneration (AMD), and the cellular defense system against oxidative damage in the retina may be compromised by deficient levels of mitochondrial antioxidant enzymes including superoxide dismutase 2 (SOD2), glutathione peroxidase (Gpx2) and thioredoxin reductase 2 (TrxR2). Interestingly, these enzymes have been shown to be regulated by miR-17* in prostate cancer. However, the function of miR-17* in RPE cells has not yet been described. The purpose of this study is to explore the role of miR-17* in oxidative stress in an established human RPE cell line.
ARPE-19 cells were treated with different concentrations of hydrogen peroxide (H2O2). RNA was extracted after 12 hours and the endogenous level of miR-17* was quantitated by qRT-PCR. ARPE-19 cells were transfected with miR-17* mimic and miR17* inhibitor with lipofectamine as transfection agent. Transfected cells were incubated with H2O2 (100uM) and t-butyl-hydroperoxide (tBH) (150uM) for 12 hours. Cell viability and apoptosis were determined by MTT and TUNEL assays. Subsequently, immunoblots were used to asses the levels of the mitochondrial antioxidant enzymes: SOD2, TrxR2, and Gpx2.
miR-17* expression in ARPE-19 cells was significantly upregulated compared to controls after incubation with increasing concentrations of H2O2 (25, 50 and 100uM) for 12 hours, but then decreased when a higher dose (200uM) was used. H2O2 and tBH-induced cell death were exacerbated by miR-17* mimic, however this effect was abrogated by co-transfection of miR-17* inhibitor. Increased expression of mitochondrial antioxidant enzymes elicited by H2O2 and tBH was supressed in transfected ARPE-19 cells with miR-17*mimic, but abolished by miR-17* inhibitor.
miR-17* aggravates the oxidative damage resulting in cell death to human ARPE-19 cells, while miR-17* inhibitor act as a potential protector from oxidative stress via regulating the expression of antioxidant enzyme. This post-transcriptional function may serve as a novel therapeutic target for AMD or other senescent ocular disorders.
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