Effect of miR-27b-3p and Nrf2 in human retinal pigment epithelial cell induced by high-glucose

AIM:To determine whether the microRNA-27b-3p(miR-27b-3p)/NF-E2-related factor 2(Nrf2)pathway plays a role in human retinal pigment epithelial(hRPE)cell response to high glucose,how miR-27b-3p and Nrf2 expression are regulated,and whether this pathway could be specifically targeted.METHODS:hRPE cells were cultured in normal glucose or high glucose for 1,3,or 6d before measuring cellular proliferation rates using cell counting kit-8 and reactive oxygen species(ROS)levels using a dihydroethidium kit.miR-27b-3p,Nrf2,NAD(P)H quinone oxidoreductase 1(NQO1)and heme oxygenase-1(HO-1)mRNA and protein levels were analyzed using reverse transcription quantitative polymerase chain reaction(RT-qPCR)and immunocytofluorescence(ICF),respectively.Western blot analyses were performed to determine nuclear and total Nrf2 protein levels.Nrf2,NQO1,and HO-1 expression levels by RT-qPCR,ICF,or Western blot were further tested after miR-27b-3p overexpression or inhibitor lentiviral transfection.Finally,the expression level of those target genes was analyzed after treating hRPE cells with pyridoxamine.RESULTS:Persistent exposure to high glucose gradually suppressed hRPE Nrf2,NQO1,and HO-1 mRNA and protein levels and increased miR-27b-3p mRNA levels.High glucose also promoted ROS release and inhibited cellular proliferation.Nrf2,NQO1,and HO-1 mRNA levels decreased after miR-27b-3p overexpression and,conversely,both mRNA and protein levels increased after expressing a miR-27b-3p inhibitor.After treating hRPE cells exposed to high glucose with pyridoxamine,ROS levels tended to decreased,proliferation rate increased,Nrf2,NQO1,and HO-1 mRNA and protein levels were upregulated,and miR-27b-3p mRNA levels were suppressed.CONCLUSION:Nrf2 is a downstream target of miR-27b-3p.Furthermore,the miR-27b-3p inhibitor pyridoxamine can alleviate high glucose injury by regulating the miR-27b-3p/Nrf2 axis.

Protective Effect and Autophagy Mechanism of Lycium barbarum Polysaccharides on Retinal Pigment Epithelial Cells Under High-Glucose Conditions

Objective:To study the effects of Lycium barbarum polysaccharide(LBP)on the proliferation,apoptosis,and autophagy of retinal pigment epithelial(RPE)cells cultured under high-glucose conditions.Methods:The ARPE-19 cell line was randomly divided into a control group(normally cultured in Dulbecco's Modified Eagle Medium/Nutrient Mixture F-12[DMEM/F-12]medium),a high-glucose group(HG;50 mmol/L glucose added to DMEM/F-12 medium),and a HG+LBP group(incubated in DMEM/F-12 medium containing 1 mg/mL LBP for 24 h,and then treated with 50 mmol/L glucose for 24 h).Following Ad-mCherry-GFP-LC3B infection,cell proliferation,apoptosis,mammalian target of rapamy-cin(mTOR)expression,and autophagic flux were determined by Cell Counting Kit-8(CCK-8),AnnexinV-APC/7-AAD Apoptosis Detection Kit,Western blot,and laser confocal microscopy,respectively.Results:The proliferation rate of ARPE-19 cells in the HG group was significantly lower than that in the control group(P<0.05),while the proliferation rate of ARPE-19 cells in the HG+LBP group was significantly higher than that in the HG group(P<0.05).The apoptosis rate of ARPE-19 cells in the HG group was significantly higher than that in the control group(P<0.05),while the apoptosis rate of ARPE-19 cells in the HG+LBP group was significantly lower than that in the HG group(P<0.05).The relative expression of phosphorylated mTOR(p-mTOR)of ARPE-19 cells in the HG group was significantly lower than that in the control group(P<0.05),with enhanced autophagic flux;when compared with the HG group,the HG+LBP group had significantly higher expression of p-mTOR(P<0.05),with diminished autophagic flux.Conclusion:LBP has a protective effect on RPE cells with high glucose-induced injury,and its mechanism may be related to LBP inhibition of high glucose-induced abnormal autophagy.

Effect of Aβ protein on inhibiting proliferation and promoting apoptosis of retinal pigment epithelial cells

AIM: To identify the effect and regulatory mechanism of amyloid β(Aβ) protein on retinal pigment epithelial(RPE)cells in cell proliferation and apoptosis, and clarify Aβ role in the pathogenesis of age-related macular degeneration(AMD).METHODS: The model of Aβ25-35 protein cytotoxicity in RPE cell was successfully established to investigate the effect of Aβ protein on RPE cells in vitro. Based on Aβprotein, the specific inhibitors(HY-50682 or BAY11-7082) or activating agent(lipopolysaccharide) was used to analyze the regulatory mechanism of Aβ protein to RPE cells on cell proliferation and apoptosis by flow cytometry, realtime polymerase chain reaction, Western blotting, enzymelinked immunosorbent assay and dual-luciferase reporter gene assay.RESULTS: The number of RPE cells, treated with Aβ25-35 from 0.3 to 60 μmol/L, significantly reduce(P<0.01), and had the dose-dependent effect. Aβ protein 60 μmol/L inhibits the G1/S phase transition(P<0.01) and down-regulated cyclin E mRNA level(P<0.01). Similarly, Aβ25-35 induced a significant increase of cell apoptosis, accompanied by the significantly higher level of activated caspase3 protein. Furthermore, nuclear factor-kappaB(NF-κB)activity and phosphorylated Iκ-Ba level would significantly lower in treated RPE cells. Using specific inhibitors or activating agent based on the Aβ, the cell numbers, NF-κB activity, phosphorylated Iκ-Ba level, receptor for advanced glycation endproducts(RAGE) gene expression levels,cyclin E mRNA level and activated caspase 3 level had accordingly changed by different methods, confirming that RAGE/NF-κB signaling pathway involved in the regulation of Aβ protein on RPE cell apoptosis and proliferation.CONCLUSION: Aβ protein inhibits cell proliferation and activates apoptosis via inactivation of the RAGE/NF-κB signaling pathway in RPE cell.

Cross-talk between microRNA-let7c and transforming growth factor-β2 during epithelial-to-mesenchymal transition of retinal pigment epithelial cells

AIM: To explore the roles of microRNA-let7 c(miR-let7 c) and transforming growth factor-β2(TGF-β2) and cellular signaling during epithelial-to-mesenchymal transition(EMT) of retinal pigment epithelial cells. METHODS: Retinal pigment epithelial(ARPE-19) cells were cultured with no serum for 12 h, and then with recombinant human TGF-β2 for different lengths of time. ARPE-19 cells were transfected with 1×106 TU/mL miR-let7 c mimcs(miR-let7 cM), miR-let7 c mimcs negative control(miR-let7cMNC) and miR-let7 c inhibitor(miR-let7 cI) using the transfection reagent. The expression of keratin-18, vimentin, N-cadherin, IKB alpha, p65 were detected by Western blot, quantitative polymerase chain reaction and immunofluorescence. RESULTS: The expression of miR-let7c was dramatically reduced and the nuclear factor-kappa B(NF-κB) signaling pathway was activated after induction by TGF-β2(P<0.05). In turn, overexpressed miR-let7 c significantly inhibited TGF-β2-induced EMT(P<0.05). However, miR-let7 c was unable to inhibit TGF-β2-induced EMT when the NF-κB signaling pathway was inhibited by BAY11-7082(P<0.01). CONCLUSION: The miR-let7 c regulates TGF-β2-induced EMT through the NF-κB signaling pathway in ARPE-19 cells.

A Trojan horse biomimetic delivery system using mesenchymal stem cells for HIF-1α siRNA-loaded nanoparticles on retinal pigment epithelial cells under hypoxia environment

AIM: To demonstrate the feasibility of mesenchymal stem cell(MSC)-mediated nano drug delivery, which was characterized by the “Trojan horse”-like transport of hypoxiainducible factor-1α small interfering RNA(HIF-1α si RNA) between MSCs and retinal pigment epithelial cells(RPE) under hypoxia environment.METHODS: Plasmid and lentivirus targeting the human HIF-1α gene were designed and constructed. HIF-1α si RNA was encapsulated into poly(lactic-co-glycolic acid) nanoparticles(PLGA-NPs) through the water-in-oil-in-water(w/o/w) multiple emulsion technique. The effect of PLGANPs uptake on the expression of HIF-1α m RNA was tested in RPE cells by real-time quantitative polymerase chain reaction(q PCR) and additional transfected conditions were used as control, including lentivirus group, nude plasmid group and blank PLGA group. MSCs were transfected with the NPs and the transfection efficacy was evaluated by flow cytometry. Transwell co-culture system of transfected MSCs and RPE cells was constructed under hypoxia environment. The effects of MSC-loaded HIF-1α si RNA PLGA-NPs on proliferation, apoptosis, and migration of RPE cells were then evaluated. The effect of transfected MSCs on HIF-1α expression of RPE cells was analyzed by using q PCR at the time points 24h, 3d, and 7d.RESULTS: The average diameter of PLGA-NPs loaded with HIF si RNA was 314.1 nm and the zeta potential was-0.36 m V. The transfection efficiency of PLGA-NPs was 67.3%±5.2% into MSCs by using flow cytometry. Compared with the lentivirus group, the PLGA-NPs loaded with HIF-1α si RNA can effectively reduce the expression of HIF-1α m RNA up to 7d in RPE(0.63±0.05 at 7d, P<0.001). In the Transwell co-culture system of transfected MSCs and RPE, the abilities of proliferation(2.34±0.17, 2.40±0.28, 2.47±0.24 at 48h, F=0.23, P=0.80), apoptosis(14.83%±2.43%, 12.94%±2.19%, 12.39%±3.21%;F=0.70, P=0.53) and migration(124.5±7.78, 119.5±5.32, 130±9.89, F=1.33, P=0.33) of the RPE cells had no differences between MSCloaded HIF-1α si RNA PLGA-NPs and other groups. The inhibition of PLGA on the HIF-1α m RNA expression in RPE cells could continue until the 7th day, the level of HIF-1α m RNA was lower than that of other groups(F=171.98, P<0.001). CONCLUSION: The delivery of PLGA-NPs loaded with HIF-1α si RNA carried by MSCs is found to be beneficial temporally for HIF-1α m RNA inhibition in RPE cells under hypoxia environment. The MSC-based bio-mimetic delivery of HIF-1α si RNA nanoparticles is a potential method for therapy against choroidal neovascularization.

Blocking VEGF signaling augments interleukin-8 secretion via MEK/ERK/1/2 axis in human retinal pigment epithelial cells

AIM:To identify proangiogenic factors engaged in neovascular age-related macular degeneration(AMD)except vascular endothelial growth factor(VEGF)from human retinal pigment epithelial(h RPE)cells and investigate the underlying mechanisms.METHODS:VEGF receptor 2(VEGFR2)in ARPE-19 cells was depleted by si RNA transfection or overexpressed through adenovirus infection.The m RNA and the protein levels of interleukin-8(IL-8)in ARPE-19 cells were measured by quantitative real-time polymerase chain reaction and enzyme-linked immunosorbent assay respectively.The protein levels of AKT,p-AKT,MEK,p-MEK,ERK1/2,p-ERK1/2,JNK,p-JNK,p38 and p-p38 were detected by Western blotting.A selective chemical inhibitor,LY3214996,was employed to inhibit phosphorylation of ERK1/2.Cell viability was determined by MTT assay.RESULTS:Knockdown of VEGFR2 in ARPE-19 cells robustly augmented IL-8 production at both the m RNA and the protein levels.Silencing VEGFR2 substantially enhanced phosphorylation of MEK and ERK1/2 while exerted no effects on phosphorylation of AKT,JNK and p38.Inhibiting ERK1/2 phosphorylation by LY3214996 reversed changes in VEGFR2 knockdown-induced IL-8 upregulation at the m RNA and the protein levels with no effects on cell viability.VEGFR2 overexpression significantly reduced IL-8 generation at the m RNA and the protein levels.CONCLUSION:Blockade of VEGF signaling augments IL-8 secretion via MEK/ERK1/2 axis and overactivation of VEGF pathway decreases IL-8 production in h RPE cells.Upregulated IL-8 expression after VEGF signaling inhibition in h RPE cells may be responsible for being incompletely responsive to anti-VEGF remedy in neovascular AMD,and IL-8 may serve as an alternative therapeutic target for neovascular AMD.

Effects of curcumin nanoparticles on proliferation and VEGF expression of human retinal pigment epithelial cells

AIM:To investigate the effects of curcumin(Cur)nanoparticles loaded with chitosan derivatives grafted by deoxycholic acid(Chit-DC)on human retinal pigment epithelial(h RPE)cell proliferation and vascular endothelial growth factor(VEGF)m RNA expression.METHODS:Cur nanoparticles were synthesized with Chit-DC as the carrier and Cur as the supported drug.Cell counting kit-8(CCK-8)method was used to detect the effects of different concentrations of Cur/Chit-DC,Chit-DC,and Cur on the proliferation of h RPE cells for different times.The changes of Cur/Chit-DC and Cur on h RPE cell cycle were determined by flow cytometry.Semi-quantitative reverse transcription-polymerase chain reaction(RT-PCR)was used to detect the m RNA expression levels of VEGF in h RPE cells treated with Cur,Chit-DC and Cur/Chit-DC at 10μg/m L for 24 h.RESULTS:Different concentrations of Chit-DC nanoparticle treated h RPE cells had no significant difference in terms of optical density(OD)values compared with the control group at 24 h and 48 h.Moreover,there was no change in the cell morphology under a light microscope.After 24 h treatment with Cur/Chit-DC and Cur,the percentage of G0-G1 phase cells increased and the percentage of S phase cells decreased in all concentration groups.Cur/Chit-DC and Cur in all concentration groups inhibited the proliferation of h RPE cells in a time and dose dependent manner,and reduced the expression level of VEGF m RNA.CONCLUSION:The Cur/Chit-DC nanoparticles can release Cur continuously and have sustained release function.Both Cur/Chit-DC nanoparticles and Cur could inhibit h RPE cells cultured in vitro,and could reduce the expression level of VEGF m RNA in h RPE cells.

Bone morphogenetic protein-6 suppresses TGF-β_(2)-induced epithelial-mesenchymal transition in retinal pigment epithelium

AIM:To evaluate the effect of bone morphogenetic protein-6(BMP-6)on transforming growth factor(TGF)-β_(2)-induced epithelial-mesenchymal transition(EMT)in retinal pigment epithelium(RPE).METHODS:Adult retinal pigment epithelial cell line(ARPE-19)were randomly divided into control,TGF-β_(2)(5μg/L),and BMP-6 small interfering RNA(siRNA)group.The cell morphology was observed by microscopy,and the cell migration ability were detected by Transwell chamber.The EMT-related indexes and BMP-6 protein levels were detected by Western blotting.Furthermore,a BMP-6 overexpression plasmid was constructed and RPE cells were divided into the control group,TGF-β_(2)+empty plasmid group,BMP-6 overexpression group,and TGF-β_(2)+BMP-6 overexpression group.The EMT-related indexes and extracellular regulated protein kinases(ERK)protein levels were detected.RESULTS:Compared with the control group,the migration of RPE cells in the TGF-β_(2) group was significantly enhanced.TGF-β_(2) increased the protein expression levels ofα-smooth muscle actin(α-SMA),fibronectin and vimentin but significantly decreased the protein levels of E-cadherin and BMP-6(P<0.05)in RPE.Similarly,the migration of RPE cells in the BMP-6 siRNA group was also significantly enhanced.BMP-6 siRNA increased the protein expression levels ofα-SMA,fibronectin and vimentin but significantly decreased the protein expression levels of E-cadherin(P<0.05).Overexpression of BMP-6 inhibited the migration of RPE cells induced by TGF-β_(2) and prevented TGF-β_(2) from affecting EMT-related biomarkers(P<0.05).CONCLUSION:BMP-6 prevents the EMT in RPE cells induced by TGF-β_(2),which may provide a theoretical basis for the prevention and treatment of proliferative vitreoretinopathy.

Effects of Lycium barbarum polysaccharide on the photoinduced autophagy of retinal pigment epithelium cells

AIM:To investigate the relationship between autophagy and apoptosis in photoinduced injuries in retinal pigment epithelium(RPE)cells and how Lycium barbarum polysaccharide(LBP)contributes to the increased of RPE cells to photoinduced autophagy.METHODS:In vitro cultures of human RPE strains(ARPE-19)were prepared and randomly divided into the blank control,model,low-dose LBP,middle-dose LBP,high-dose LBP,and 3-methyladenine(3MA)groups.The viability of the RPE cells and apoptosis levels in each group were tested through cell counting kit-8(CCK8)method with a flow cytometer(Annexin V/PI double staining technique).The expression levels of LC3II,LC3I,and P62 proteins were detected with the immunofluorescence method.The expression levels of beclin1,LC3,P62,PI3K,P-mTOR,mTOR,P-Akt,and Akt proteins were tested through Western blot.RESULTS:LBP considerably strengthens cell viability and inhibits the apoptosis of RPE cells after photoinduction.The PI3K/Akt/mTOR signal pathway is activated because of the upregulation of the phosphorylation levels of Akt and mTOR proteins,and thus autophagy is inhibited.CONCLUSION:LBP can inhibit the excessive autophagy in RPE cells by activating the PI3K/Akt/mTOR signaling pathways and thereby protect RPE cells from photoinduced injuries.

YM155 inhibits retinal pigment epithelium cell survival through EGFR/MAPK signaling pathway

AIM:To investigate YM155’s effect on retinal pigment epithelium(RPE)cells’viability and the potential regulatory mechanisms.METHODS:Human immortalized RPE cell lines(ARPE-19 cell line)were processed with YM155 and epidermal growth factor(EGF).ARPE-19 cell viability was detected by methyl thiazolyl tetrazolium assay,and apoptosis was tested by flow cytometry assay.ARPE-19 cell proliferation was assessed with bromodeoxyuridine tagged incorporation assay,and migration ability was evaluated via a wound-healing assay.Epidermal growth factor receptor(EGFR)/MAPK pathway proteins were tested via immunoblotting.EGFR localization was examined by immunofluorescence assay.RESULTS:YM155 suppressed ARPE-19 cells’viability in a time and concentration-dependent manner.A high dose of YM155 caused a small amount of ARPE-19 cell death.YM155 significantly diminished the ARPE-19 cells’proliferative and migrative capacity.YM155 downregulated total EGFR and phosphorylated external signalregulated protein kinase(ERK),and it up-regulated the phosphorylation of P38 MAPK and c-Jun N-terminal kinase(JNK).YM155 induced endocytosis of EGFR in ARPE-19 cell.YM155 also attenuated EGF-induced ARPE-19 cells’proliferative and migrative capacity.Moreover,YM155 significantly decreased the expression of phosphorylated EGFR and ERK after treated by EGF.CONCLUSION:YM155 inhibits RPE cell survival,the cell proliferative and migrative capacity,and it effectuates a small amount of cell death through the EGFR/MAPK signaling pathway.YM155 might,therefore,be an agent to prevent and treat abnormal RPE cell survival in proliferative vitreoretinopathy.

Lutein-stevioside nanoparticle attenuates H_(2)O_(2)-induced oxidative damage in ARPE cells

In order to improve the bioavailability of lutein(LUT),a novel lutein-stevio side nanoparticle(LUT-STE)were prepared previously,but the information about LUT-STE on protecting of eye health was limited.This study investigated the effect of LUT-STE on antioxidant activity of H_(2)O_(2)-induced human retinal pigment epithelial(ARPE)cells.LUT and LUT-STE(final concentration of 5μg/mL)significantly enhanced cell viability from(74.84±5.10)%to(81.92±10.01)%(LUT)and(89.33±4.34)%(LUT-STE),and inhibited the cell apoptosis(P<0.05).After pretreatment with LUT-STE in ARPE cells,the levels of superoxide dismutase(SOD),catalase(CAT)and glutathion peroxidase(GSH-Px)in ARPE cells were significantly increased(P<0.05),the contents of reactive oxygen species(ROS)and malondialdehyde(MDA)were decreased.In addition,the vascular endothelial growth factor(VEGF)levels were inhibited by 13.61%and 17.39%,respectively,pretreatment with LUT and LUT-STE.Western blotting results showed that the pretreatment with LUT-STE inhibited the expression of caspase-9 and caspase-3 and up-regulated Bcl-2/Bax pathway to inhibit H_(2)O_(2)-induced apoptosis.In summary,the novel delivery LUT-STE had more pronounced inhibitory effect on H_(2)O_(2)-induced damage in human ARPE cells.

Autophagy dysregulation mediates the damage of high glucose to retinal pigment epithelium cells

AIM:To observe the role and mechanism of autophagy in retinal pigment epithelial cell(RPE)damaged by high glucose,so as to offer a new idea for the treatment of diabetic retinopathy(DR).METHODS:ARPE-19,a human RPE cell line cultured in vitro was divided into the normal control(NC),autophagy inhibitor 3-methyladenine(3-MA),high-glucose(HG),and HG+3-MA groups.Cell viability was detected by CCK-8 assay and the apoptosis rate was measured by flow cytometry.The protein expressions of apoptosis markers,including Bax,Bcl-2,and Caspase-3,as well as autophagy marker including microtubule-related protein 1 light chain 3(LC3),p62,and mechanistic target of rapamycin(m TOR)were detected by Western blotting.Autophagic flux was detected by transfection with Ad-m Cherry-GFP-LC3 B.RESULTS:Under high glucose conditions,the viability of ARPE-19 was decreased,and the apoptosis rate increased,the protein expressions of Bax,Caspase-3,and LC3-II/LC3-I were all increased and the expressions of Bcl-2,p62 and p-m TOR decreased,and autophagic flux was increased compared with that of the controls.Treatment with 3-MA reversed all these changes caused by high glucose.CONCLUSION:The current study demonstrates the mechanisms of cell damage of ARPE-19 through high glucose/m TOR/autophagy/apoptosis pathway,and new strategies for DR may be developed based on autophagy regulation to manage cell death of RPE cells.

LIN28A attenuates high glucose-induced retinal pigmented epithelium injury through activating SIRT1-dependent autophagy

AIM:To evaluate the effects of LIN28A(human)on high glucose-induced retinal pigmented epithelium(RPE)cell injury and its possible mechanism.METHODS:Diabetic retinopathy model was generated following 48h of exposure to 30 mmol/L high glucose(HG)in ARPE-19 cells.Quantitative real-time polymerase chain reaction(qRT-PCR)and Western blot tested the expression of the corresponding genes and proteins.Cell viability as well as apoptosis was determined through cell counting kit-8(CCK-8)and flow cytometry assays.Immunofluorescence assay was adopted to evaluate autophagy activity.Caspase 3 activity,oxidative stress markers,and cytokines were appraised adopting their commercial kits,respectively.Finally,ARPE-19 cells were preincubated with EX527,a Sirtuin 1(SIRT1)inhibitor,prior to HG stimulation to validate the regulatory mechanism.RESULTS:LIN28A was downregulated in HG-challenged ARPE-19 cells.LIN28A overexpression greatly inhibited HGinduced ARPE-19 cell viability loss,apoptosis,oxidative damage as well as inflammatory response.Meanwhile,the repressed autophagy and SIRT1 in ARPE-19 cells challenged with HG were elevated after LIN28A overexpression.In addition,treatment of EX527 greatly inhibited the activated autophagy following LIN28A overexpression and partly abolished the protective role of LIN28A against HG-elicited apoptosis,oxidative damage as well as inflammation in ARPE-19 cells.CONCLUSION:LIN28A exerts a protective role against HG-elicited RPE oxidative damage,inflammation,as well as apoptosis via regulating SIRT1/autophagy.

Repression of retinal microvascular endothelial cells by transthyretin under simulated diabetic retinopathy conditions

AIM: To investigate biological effects of transthyretin(TTR) on the development of neovascularization under simulated diabetic retinopathy(DR) condition associated with high glucose and hypoxia. METHODS: Human retinal microvascular endothelial cells(h RECs) were cultured in normal and simulated DR environments with high glucose and hypoxia. The normal serum glucose concentration is approximately 5.5 mmol/L;thus, hyperglycemia was simulated with 25 mmol/L glucose, while hypoxia was induced using 200 μmol/L Co Cl2. The influence of TTR on h RECs and human retinal pigment epithelial cells(h RPECs) was determined by incubating the cells with 4 μmol/L TTR in normal and abnormal media. A co-culture system was then employed to evaluate the effects of h RPECs on h RECs. RESULTS: Decreased h RECs and h RPECs were observed under abnormal conditions, including high-glucose and hypoxic media. In addition, h RECs were significantly inhibited by 4 μmol/L exogenous TTR during hyperglycemic culture. During co-culture, h RPECs inhibited h RECs in both the normal and abnormal environments.CONCLUSION: h REC growth is inhibited by exogenous TTR under simulated DR environments with high-glucose and hypoxic, particularly in the medium containing 25 mmol/L glucose. h RPECs, which manufacture TTR in the eye, also represses h RECs in the same environment. TTR is predicted to inhibit the proliferation of h RECs and neovascularization.

Hepatocyte growth factor promotes retinal pigment epithelium cell activity through MET/AKT signaling pathway

AIM:To explore the effects of hepatocyte growth factor(HGF)on retinal pigment epithelium(RPE)cell behaviors.METHODS:The human adult retinal pigment epithelial cell line-19(ARPE-19)were treated by HGF or mesenchymalepithelial transition factor(MET)inhibitor SU11274 in vitro.Cell viability was detected by a Cell Counting Kit-8 assay.Cell proliferation and motility was detected by a bromodeoxyuridine incorporation assay and a wound healing assay,respectively.The expression levels of MET,phosphorylated MET,protein kinase B(AKT),and phosphorylated AKT proteins were determined by Western blot assay.The MET and phosphorylated MET proteins were also determined by immunofluorescence assay.RESULTS:HGF increased ARPE-19 cells’viability,proliferation and migration,and induced an increase of phosphorylated MET and phosphorylated AKT proteins.SU11274 significantly reduced cell viability,proliferation,and migration and decreased the expression of MET and AKT proteins.SU11274 suppressed HGF-induced increase of viability,proliferation,and migration in ARPE-19 cells.Additionally,SU11274 also blocked HGF-induced phosphorylation of MET and AKT proteins.CONCLUSION:HGF enhances cellular viability,proliferation,and migration in RPE cells through the MET/AKT signaling pathway,whereas this enhancement is suppressed by the MET inhibitor SU11274.HGF-induced MET/AKT signaling might be a vital contributor of RPE cells survival.