title: Suppression of the proliferation of hypoxia-Induced retinal pigment epithelial cell by rapamycin through the /mTOR/HIF-1α/VEGF/ signaling.
abstract: Rapamycin, a highly specific inhibitor of mammalian target of rapamycin (mTOR), exhibits significant antitumor/antiangiogenic activity in human cancer cells. Its effect on the retinal pigment epithelial (RPE) cells was rarely investigated. This study assessed the proliferation of hypoxia-induced RPE and the inhibitory effects of rapamycin using 3-(4,5-dimethylthazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and examined the expression of hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) in RPE cells with or without rapamycin under normoxic and hypoxic conditions using real-time PCR and Western blot. We found that hypoxia increased the levels of mTOR, HIF-1α, and VEGF. The suppression of HIF-1α and VEGF by rapamycin was associated with dephosphorylation of mTOR and the downstream effector ribosomal protein S6 kinase (P70S6K) and 4E-binding protein-1 (4E-BP1) of mTORC1. Rapamycin only inhibited the protein levels and did not change the mRNA expression of HIF-1α. No cytotoxicity to the RPE cells by rapamycin was caused under either normoxia or hypoxia. Our data suggest that rapamycin suppresses hypoxia-induced RPE cell proliferation through a mechanism related to the targeting of mTOR/HIF-1α/VEGF signaling. Rapamycin may potentially provide a safe and effective novel treatment for choroidal vascular disease.
authors.affiliation: Department of Ophthalmology, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning Province, China.
authors.forename: Ning-Ning
authors.initials: NN
authors.lastname: Liu
authors.affiliation: Department of Ophthalmology, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning Province, China.
authors.forename: Ning
authors.initials: N
authors.lastname: Zhao
authors.affiliation: Department of Ophthalmology, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning Province, China.
authors.forename: Na
authors.initials: N
authors.lastname: Cai
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D018797:Cell Cycle Proteins; D015687:Cell Hypoxia / Q000187:drug effects; D002460:Cell Line / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism; D055213:Retinal Pigment Epithelium / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D020123:Sirolimus / Q000494:pharmacology*; D058570:TOR Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D018797:Cell Cycle Proteins; C087000:EIF4EBP1 protein, human; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D010750:Phosphoproteins; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; C546842:MTOR protein, human; D058570:TOR Serine-Threonine Kinases; D020123:Sirolimus
keywords: 4E-BP1; HIF-1α; P70S6K; VEGF; hypoxia; mTOR; rapamycin; retinal pigment epithelial cells