Inhibition of EGFR attenuates EGF-induced activation of retinal pigment epithelium cell via EGFR/AKT signaling pathway.

AIM: To explore the effect of epidermal growth factor receptor (EGFR) inhibition by erlotinib and EGFR siRNA on epidermal growth factor (EGF)-induced activation of retinal pigment epithelium (RPE) cells. METHODS: Human RPE cell line (ARPE-19 cells) was activated by 100 ng/mL EGF. Erlotinib and EGFR siRNA were used to intervene EGF treatment. Cellular viability, proliferation, and migration were detected by methyl thiazolyl tetrazolium (MTT) assay, bromodeoxyuridine (BrdU) staining assay and wound healing assay, respectively. EGFR/protein kinase B (AKT) pathway proteins and N-cadherin, α-smooth muscle actin (α-SMA), and vimentin were tested by Western blot assay. EGFR was also determined by immunofluorescence staining. RESULTS: EGF treatment for 24h induced a significant increase of ARPE-19 cells' viability, proliferation and migration, phosphorylation of EGFR/AKT proteins, and decreased total EGFR expression. Erlotinib suppressed ARPE-19 cells' viability, proliferation and migration through down regulating total EGFR and AKT protein expressions. Erlotinib also inhibited EGF-induced an increase of proliferative and migrative ability in ARPE-19 cells and clearly suppressed EGF-induced EGFR/AKT proteins phosphorylation and decreased expression of N-cadherin, α-SMA, and vimentin proteins. Similarly, EGFR inhibition by EGFR siRNA significantly affected EGF-induced an increase of cell proliferation, viability, and migration, phosphorylation of EGFR/AKT proteins, and up-regulation of N-cadherin, α-SMA, and vimentin proteins. CONCLUSION: Erlotinib and EGFR-knockdown suppress EGF-induced cell viability, proliferation, and migration via EGFR/AKT pathway in RPE cells. EGFR inhibition may be a possible therapeutic approach for proliferative vitreoretinopathy (PVR).

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 mesenchymal-epithelial 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.

Clinical efficacy and changes of serum VEGF-A, VEGF-B, and PLGF after conbercept treating neovascular age-related macular degeneration.

AIM: To evaluate the clinical efficacy and systemic safety profile of conbercept in clinical practice on vascular endothelial growth factor (VEGF)-A, VEGF-B, and placental growth factor (PLGF) levels after intravitreal injections for the neovascular age-related macular degeneration (AMD). METHODS: Thirty-five patients (35 eyes) with neovascular AMD received intravitreal injections of conbercept treatment with pro re nata protocol. Best-corrected visual acuity (BCVA) and central retinal thickness (CRT) were detected before the intravitreal injection and at 1, 3, and 12mo after conbercept treatment. The levels of serum VEGF-A, VEGF-B, and PLGF were measured by enzyme-linked immunosorbent assay before the injection and 1 and 12mo after conbercept treatments. RESULTS: At baseline, the mean BCVA score was 39.89±14.64 letters. The mean BCVA scores were 51.03±15.78, 56.71±14.38, and 52.49±10.16 letters at 1, 3, and 12mo after conbercept treatment, and the BCVA improvements were all significant, respectively (P<0.05). At baseline, the mean CRT was 436.7±141.9 µm. At 1, 3, and 12mo after conbercept treatment, the mean CRT values were 335.1±147.8, 301.1±116.5, and 312.2±98.22 µm, and the CRT improvements were all significant, respectively (P<0.05). At baseline, 1 and 12mo after conbercept treatment, the mean levels of serum VEGF-A were 1013.8±454.3, 953.1±426.4, and 981.5±471.7 pg/mL, the mean levels of serum VEGF-B were 46.93±24.76, 42.99±19.16, and 45.32±18.76 pg/mL, the mean levels of serum PLGF at these points were 251.7±154.9, 241.3±166.7, and 245.6±147.2 pg/mL, respectively. Compared with the baseline, the levels of serum VEGF-A, VEGF-B, and PLGF did not significantly change at 1 and 12mo after conbercept treatment, respectively (P>0.05). CONCLUSION: Conbercept intravitreal injection leads to BCVA and CRT improvement, however, it does not significantly affect systemic serum VEGF-A, VEGF-B, and PLGF levels at 1 and 12mo after intravitreal injection treating neovascular AMD.

Initial subduction-related magmatism in southern Alaska identified by geochemistry and zircon Hf-O isotopes.

Abundant arc-type magmatic and metamorphic rocks exist on Earth today, which provide insights into the equilibrium state of the subduction process. However, magmatic samples generated during the initial stage of subduction is largely unknown. This hinders our understanding of the subduction initiation process and by inference, the onset of plate tectonics as well as the history of crustal formation. To address this issue, we carried out a comprehensive geochemical-geochronological study of a suite of Late Triassic to mid-Jurassic plutonic rocks from southern Alaska that potentially represent magmas from the initial to mature stages of arc formation. While all studied samples show typical arc-type geochemical signatures, i.e., enrichment of large ion lithophile elements (LILEs) and depletion of high field strength elements (HFSEs) relative to the heavy rare earth elements (HREEs), the Late Triassic trondhjemites show unique geochemical features such as strongly positive εHf(t) and εNd(t) coupled with lower δ18O (average 4.77‰ ± 0.09‰). These signatures, along with its higher zircon saturation temperatures compared with younger plutonic rocks, are best explained by shallow partial melting of subducting high-temperature hydrothermally altered lower oceanic crust (i.e., gabbro). If true, these surprising findings would open up new ways to study subduction initiation which would have important bearing on future research on the onset of global plate tectonics and the formation of the continental crust.