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Rapamycin inhibits proliferation of hemangioma endothelial cells by reducing HIF-1-dependent expression of VEGF.

ABSTRACT: Hemangiomas are tumors formed by hyper-proliferation of vascular endothelial cells. This is caused by elevated vascular endothelial growth factor (VEGF) signaling through VEGF receptor 2 (VEGFR2). Here we show that elevated VEGF levels produced by hemangioma endothelial cells are reduced by the mTOR inhibitor rapamycin. mTOR activates p70S6K, which controls translation of mRNA to generate proteins such as hypoxia inducible factor-1 (HIF-1). VEGF is a known HIF-1 target gene, and our data show that VEGF levels in hemangioma endothelial cells are reduced by HIF-1? siRNA. Over-expression of HIF-1? increases VEGF levels and endothelial cell proliferation. Furthermore, both rapamycin and HIF-1? siRNA reduce proliferation of hemangioma endothelial cells. These data suggest that mTOR and HIF-1 contribute to hemangioma endothelial cell proliferation by stimulating an autocrine loop of VEGF signaling. Furthermore, mTOR and HIF-1 may be therapeutic targets for the treatment of hemangiomas.

SUBMITTER: Medici D

PROVIDER: S-EPMC3416768 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature

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Rapamycin inhibits proliferation of hemangioma endothelial cells by reducing HIF-1-dependent expression of VEGF.

Medici Damian D Olsen Bjorn R BR

PloS one 20120810 8

Hemangiomas are tumors formed by hyper-proliferation of vascular endothelial cells. This is caused by elevated vascular endothelial growth factor (VEGF) signaling through VEGF receptor 2 (VEGFR2). Here we show that elevated VEGF levels produced by hemangioma endothelial cells are reduced by the mTOR inhibitor rapamycin. mTOR activates p70S6K, which controls translation of mRNA to generate proteins such as hypoxia inducible factor-1 (HIF-1). VEGF is a known HIF-1 target gene, and our data show th ...[more]

PMID: 22900063

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Project description:The present study aimed to investigate the significant role of ?-elemene in mouse models of oxygen-induced retinopathy (OIR). C57BL/6J neonatal mice were used to establish OIR models. They were divided into four groups: Normoxia, OIR, OIR control and OIR?treated. Mice in the OIR group were exposed to 75±5% oxygen for 5 days and returned to a normal oxygen environment on postnatal day 12 (P12). The OIR treated group was intravitreally injected with 1 µl ??elemene on P12 and subsequently returned to a normal oxygen environment for 5 days (P12?P17). Retinas were obtained on P17. Retinal neovascularization (RNV) was detected using adenosine diphosphatase staining and analyzed by counting the nuclei of neovascular endothelial cells. Vascular endothelial growth factor (VEGF) expression was determined by reverse transcription?quantitative polymerase chain reaction, immunohistochemistry and western blot analysis. MicroRNA (miRNA/miR) microarrays were used to screen out differentially expressed miRNAs between the OIR and ??elemene?treated groups. Binding the 3'?untranslated region (UTR) of VEGF and miR?27a was confirmed using luciferase assays. It was found that high oxygen concentrations accelerated RNV and increased the number of preretinal neovascular cells; ??elemene treatment reduced these effects. VEGF mRNA and protein expression was higher in the OIR and OIR control groups, compared with the normoxia and OIR?treated groups. Further, it was shown that miR?22, miR?181a?1, miR?335?5p, miR?669n, miR?190b, miR?27a and miR?93 were upregulated in the OIR?treated group, and downregulated in the OIR group. The prediction websites TargetScan and miRanda revealed that VEGF contained a potential miR?27a binding site in its 3'?untranslated region (UTR). Luciferase assays demonstrated that miR?27a directly bound to the 3'?UTR of VEGF. In vitro experiments demonstrated that miR?27a inhibited VEGF expression. In addition, ??elemene treatment upregulate miR?27a expression in vivo and in vitro. When miR?27a expression was depleted by miR?27a inhibitor, the protective effect of ??elemene on RNV was eliminated. The present study demonstrated that ??elemene reduced RNV in mouse OIR models via miR?27a upregulation, leading to reduced VEGF expression. This finding may contribute to the development of novel therapeutic strategies for human retinopathy.

Dataset Information

Rapamycin inhibits proliferation of hemangioma endothelial cells by reducing HIF-1-dependent expression of VEGF.

Publications

Rapamycin inhibits proliferation of hemangioma endothelial cells by reducing HIF-1-dependent expression of VEGF.

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