title: Vascular endothelial growth factor regulates primate choroid-retinal endothelial cell proliferation and tube formation through PI3K/Akt and MEK/ERK dependent signaling.
abstract: Vascular endothelial growth factor (VEGF) is a hypoxia-induced angiogenic protein that exhibits a broad range of biological and pathological effects in wet age-related macular degeneration and proliferative diabetic retinopathy. However, its specific mechanism is still not fully understood. Here, we examined the effects of VEGF on choroid-retinal endothelial cells (RF/6A) proliferation and tube formation, and the underlying signal pathways responsible in this process. RF/6A cells were pretreated with MEK inhibitor or PI3K inhibitor, and then incubated in a hypoxia chamber. Real-time PCR and Western blot analysis were carried out to explore VEGF expression on mRNA and protein levels. Hypoxia inducible factor-1α (HIF-1α) and VEGFR2 expression levels were also investigated in the presence and absence of hypoxic conditions. CCK-8 analysis and tube formation assay were tested under hypoxia, exogenous recombinant VEGF, and different signal pathway inhibitors, respectively. Mean while, the PI3K/Akt and MEK/ERK pathways in this process were also investigated. Our results showed that VEGF, HIF-1α, VEGFR2, p-ERK, and p-Akt were up-regulated in RF/6A cells under hypoxic conditions. MEK inhibitor (PD98059) and PI3K inhibitor (LY294002) decreased ERK and Akt activity, respectively, and reduced VEGF expression. VEGF-induced RF/6A proliferation and tube formation requires MEK/ERK and PI3K/Akt signaling, and both of the two pathways were needed in regulating VEGF expression. These suggest that VEGF plays an important role in RF/6A proliferation and tube formation, and MEK/ERK and PI3K/Akt pathway may be responsible for this process.
authors.affiliation: Department of Ophthalmology, Zhongshan Hospital, Fudan University, Shanghai, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Jin
authors.forename: Fei
authors.initials: F
authors.lastname: Yuan
authors.forename: Min-qian
authors.initials: MQ
authors.lastname: Shen
authors.forename: Yi-fan
authors.initials: YF
authors.lastname: Feng
authors.forename: Qi-liu
authors.initials: QL
authors.lastname: He
mesh_terms: D000818:Animals; D015153:Blotting, Western; D015687:Cell Hypoxia / Q000187:drug effects; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D002829:Choroid / Q000166:cytology*; D003094:Collagen / Q000378:metabolism; D015536:Down-Regulation / Q000187:drug effects; D004338:Drug Combinations; D042783:Endothelial Cells / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology; D004789:Enzyme Activation / Q000187:drug effects; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism; D042541:Intracellular Space / Q000187:drug effects / Q000201:enzymology; D007797:Laminin / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008253:Macaca mulatta / Q000378:metabolism*; D018919:Neovascularization, Physiologic / Q000187:drug effects; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011509:Proteoglycans / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D012160:Retina / Q000166:cytology*; D015854:Up-Regulation / Q000187:drug effects; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism* / Q000494:pharmacology; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism
chemical_list: D004338:Drug Combinations; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D007797:Laminin; D047428:Protein Kinase Inhibitors; D011509:Proteoglycans; D042461:Vascular Endothelial Growth Factor A; C059485:matrigel; D003094:Collagen; D019869:Phosphatidylinositol 3-Kinases; D040301:Vascular Endothelial Growth Factor Receptor-2; D051057:Proto-Oncogene Proteins c-akt