ABSTRACT
Background Studies showed that microRNA (miR)-375 suppresses the growth,apoptosis,migration and adhesion of tumor cells,and it plays a regulation to the changes of vascular endothelial growth factor (VEGF) in tumor tissue to arrest neovascularization.However,whether miR-375 intervenes the formation of new blood vessel in eyes is unelucidated.Objective This study was to explore the effects of miR-375 on human retinal capillary endothelial cells (HRCECs) function induced by hypoxia.Methods HRCECs were cultured using IMDM and divided into normal control group,CoCl2 model group,CoCl2 +miR-375 mimic group,CoCl2 +miR-375 mimic control group,CoCl2+miR-375 inhibitor group and CoCl2 +miR-375 inhibitor control group,and hypoxia cell models were created by adding 200 μmol/L CoCl2.MiR-375 and frizzled 4 (FZD4) small interfering RNA (siRNA) were transfected into the cells by 50 nmol/L miRNA lipidosome for 48 hours.The proliferation of the cells was detected by MTT assay;migrated number of the cells was examined by Transwell chamber assay;ELISA was employed to detect the concentrations of VEGF and VE-cadherin in the medium;the expression of β-catenin,cyclinD1,matrix metalloproteinase-2 (MMP2) and VEGF proteins were analyzed by Western blot;tube length of vessel formation was evaluated by Matrigel assay.Cultured cells were divided into normal control group,CoCl2 model group,CoCl2 +mock group and CoCl2 + FZD4 siRNA group,the relative expression of FZD4,a miR-375 targeted gene,was detected by luciferase reporter.Results The relative expression of miR-375 mRNA was significantly increased in the CoCl2 +miR-375 mimic group compared with the CoCl2 + miR-375 mimic control group and reduced in the CoCo2 + miR-375 inhibitor group compared with the CoCo2 + miR-375 inhibitor control group (t =-19.237,8.764,both at P＜0.01),with a higher transfected efficacy for miR-375.The cell proliferative fold,migrated cell number,VEGF and VE-Cadherin contents in the medium and the tube length were significantly different among the CoCl2 model group,CoCl2 +miR-375 mimic group,CoCl2 +miR-375 mimic control group,CoCl2 +miR-375 inhibitor group and CoCl2 +miR-375 inhibitor control group (F =24.324,26.776,14.113,19.225,15.040,all at P＜0.001),and those in the CoCl2 +miR-375 mimic group were evidently reduced in the CoCl2 +miR-375 mimic group compared with the CoCl2 +miR-375 mimic control group,while those in the CoCl2 +miR-375 inhibitor group were considerably elevated in comparison with the CoCl2 +miR-375 inhibitor control group (all at P＜0.01).The expressions of β3-catenin,cyclinD1,MMP2 and VEGF protein were significantly different among the normal control group,CoCl2 model group,CoCl2 +miR-375 mimic group,CoCl2+miR-375 mimic control group,CoCl2 +miR-375 inhibitor group and CoCl2 +miR-375 inhibitor control group (F=11.753,13.283,16.770,10.334,all at P＜0.001).In addition,the cell proliferative fold,migrated cell number and the tube length were significantly increased in the CoCl2 model group and CoCl2+mock group,and those in the CoCl2+FZD4 siRNA group were decreased in comparison with the CoCl2 +mock group (all at P＜0.05).Conclusions MiR-375 inhibits the growth,migration and tube formation ability of HRCECs in hypoxic status probably by regulating the activation of Wnt pathway via directly targeting FZD4.
ABSTRACT
Background Pluripotent stem cell-derived retinal pigment epithelial (RPE) cells holds great promise for the treatment of age-related macular degeneration (AMD) and retinitis pigmentosa (RP),but the poor induction efficiency and the according high cost of RPE differentiation hindere its clinical applications.Curcumin is proved to have a promoting effect on the induced differentiation of embryonic stem cells (ESCs).However,the mechanism of curcumin on differentiation of human ESCs into RPE-like cells remains unclear.Objective This study aimed to explore the underlying molecular mechanism of curcumin on directed differentiation of human ESCs into RPE-like cells.Methods Human ESCs strains were cultured in the Matrigel-coated 6-well plate with mTeSRTM 1 medium until over-confluence,and basic fibroblast growth factor was withdrawn there after to induce automatic differentiation.Curcumin at the final concentration 1 μmol/L was added in the first day of differentiation for 24 hours,and the cells without curcumin in the medium served as the control group.Total RNA and protein were extracted at 3 weeks and 5 weeks after induction.RT-PCR,Western blot and immunofluorescence were performed to examine the expressions of the biomarks of stem cells and RPE cells as well as Wnt/β-catenin signaling pathway components.The endocytosis of polystyrene microsphere by induced RPE (iRPE) cells was investigated to verify their function of phagocytosis which features RPE cells.Results Pigmented cells were found from 3 weeks through 5 weeks after induction in the curcumin group,but only less pigmented cells were seen in the fifth week after induction in the control group.In the third and fifth week after induction,the relative expression levels of NANOG mRNA in the iRPE cells were significantly lower than those in the control group (t =13.086,P =0.022;t =34.186,P =0.004),and the relative expression levels of Pax6,RX,CRALBP and RPE65 mRNA were higher in the curcumin group than those of the control group (all at P＜0.01).Western blot assay showed that the expressing bands for CRALBP,RPE65 and MITF enhanced in iRPE cells with a similar appearance in human RPE cells.However,these expressions were all absent in human ESCs.Immunofluorescence staining showed the positive expressions of Pax6,MITF and ZO-1 in cytoplasm of iRPE cells in the curcumin group with a purified efficacy 100％.The fluorescence dye-doped polystyrene microspheres in cytoplasm were obvious in the iRPE cells like positive controls,but the polystyrene microsphere was absent in the negative controls.From 3 weeks through 5 weeks after induced,the relative expression levels of Lef1,MYC and TCF7 mRNA (the dwnstream target genes of Wnt signaling pathway),FZD3 mRNA (Wnt receptor),Wnt2B mRNA (Wnt ligand) and Wnt7B mRNA were significantly reduced in the curcumin group compared with the control group (all at P＜0.01).Conclusions Curcumin promotes the differentiation of human ESCs into RPE-like cells by stimulating the activation of Wnt signaling pathway,and therefore accelerate the differentiation and mature of iRPE cells.