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Suppression of the proliferation of hypoxia‐Induced retinal pigment epithelial cell by rapamycin through the / mTOR/HIF‐1α/VEGF / signaling
Author(s) -
Liu NingNing,
Zhao Ning,
Cai Na
Publication year - 2015
Publication title -
iubmb life
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.132
H-Index - 113
eISSN - 1521-6551
pISSN - 1521-6543
DOI - 10.1002/iub.1382
Subject(s) - pi3k/akt/mtor pathway , mtorc1 , ribosomal protein s6 , rptor , mechanistic target of rapamycin , cell growth , microbiology and biotechnology , vascular endothelial growth factor , hypoxia (environmental) , biology , kinase , signal transduction , chemistry , cancer research , p70 s6 kinase 1 , biochemistry , vegf receptors , organic chemistry , oxygen
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. © 2015 IUBMB Life, 67(6):446–452, 2015