Opposing roles for HIF-1α and HIF-2α in the regulation of angiogenesis by mononuclear phagocytes.
Blood
; 117(1): 323-32, 2011 Jan 06.
Article
em En
| MEDLINE
| ID: mdl-20952691
ABSTRACT
Macrophages contribute to tumor growth through the secretion of the proangiogenic molecule vascular endothelial growth factor (VEGF). We previously observed that monocytes treated with the cytokine granulocyte-macrophage colony-stimulating factor (GM-CSF) produce a soluble form of the VEGF receptor-1 (sVEGFR-1), which neutralizes VEGF biologic activity. The VEGF and VEGFR-1 promoters both contain a hypoxia regulatory element, which binds the hypoxia-inducible factor (HIF) transcription factors under hypoxic conditions. Based on this observation, we examined VEGF and sVEGFR-1 production from monocytes cultured at various O(2) concentrations. The amount of sVEGFR-1 production observed from GM-CSF-treated monocytes increased with decreasing levels of O(2). This sVEGFR-1 was biologically active and sequestered VEGF. To evaluate the role of the HIFs in sVEGFR-1 production, we used macrophages with a genetic deletion of HIF-1α. HIF-1α(-/-) macrophages cultured with GM-CSF at hypoxia secreted diminished amounts of VEGF compared with HIF-1α(+/+) macrophages, whereas sVEGFR-1 secretion was unaffected. In contrast, siRNA-mediated knockdown of HIF-2α inhibited the production of sVEGFR-1 in response to GM-CSF and low O(2), whereas VEGF production was unaffected. These studies suggest that hypoxia, generally thought to promote angiogenesis, can induce antiangiogenic behavior from macrophages within a GM-CSF-rich environment. Furthermore, these results suggest specific and independent roles for HIF-1α and HIF-2α in hypoxic macrophages.
Texto completo:
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Base de dados:
MEDLINE
Assunto principal:
Sistema Fagocitário Mononuclear
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Endotélio Vascular
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Neovascularização Fisiológica
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Fatores de Transcrição Hélice-Alça-Hélice Básicos
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Subunidade alfa do Fator 1 Induzível por Hipóxia
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Hipóxia
Idioma:
En
Ano de publicação:
2011
Tipo de documento:
Article