Effect of IGF-1 on expressions of VEGF under suppression of HIF-1α by shRNA in cultured human RPE cells / 中华实验眼科杂志

ABSTRACT

BackgroundProliferative vitreo-retinal disease (PVD)is one group of ocular complications marked by the enhanced proliferation of various cells included retinal pigment epithelial (RPE) cells.Insulin-like growth factor-1 (IGF-1)and vascular endothelial growth factor(VEGF) are implicated in the aberrant cell proliferation and pathological neovascularization that characterizes PVD,but the signaling mechanism is unclear now. Objective This study was to explore the effect of IGF-1 on VEGF in cultured human RPE cells under the small hairpin loop RNA (shRNA) keeping hypoxia-inducible factor-1 α ( HIF-1 α) silencing. Methods Human retinas were isolated from 4 healthy male donors,and the RPE cells were harvested and cultured.The ceils were identified using anti-human keratin antibody.The third to fifth generation of human RPE cells were used in the experiment.One target site of HIF-1α mRNA was chosen by certain design principle,and shRNA was designed and synthesized by the target site and transferred into the cells in vitro,and then the cells were cultivated with 50 μg/L IGF-1 for 24 hours.The mRNA and protein expressions of HIF-1α and VEGF were detected by RT-PCR and Western blot respectively. Results Cultured human RPE cells showed the flat irregularly multangular shape,and 97％cells appeared the positive response for keratin.HIF-1α mRNA expression in human RPE cells was significantly lower in 50 μg/L IGF-1 group than the 0 pg/L IGF-1 group ( 1.49±0.18 vs 1.46±0.17 ) ( t =0.335,P =0.743 ),however,the expressing levels of HIF-1α protein( 1049.86±172.54 vs 0.00±0.00) and VEGF mRNA(0.95±0.15 vs 0.35±0.07) and VEGF protein (391.98±56.77 vs 214.36±37.15)were raised in the 50 μg/L IGF-I group compared with 0 μg/L IGF-1 group (t=16.098,9.935,6.928,P＜0.05).After the HIF-1α-specific shRNA was transferred into cultured RPE cells,the expressions of both HIF-1α mRNA and its protein significantly decreased in RPE cells under 50 μg/L IGF-1 concentration condition( F=68.679,89.904,P=0.000),moreover,the expression of VEGF mRNA and its protein were significantly lowed(F=21.770,6.205,P＜0.05). ConclusionsIGF-1 promotes the accumulation of HIF-1α protein and induce the expression of VEGF in human RPE cells,which probably play a pivotal role in the development of PVD.