Abstract
The von Hippel-Lindau tumor suppressor protein (pVHL) is a substrate receptor for the mammalian SCF-2 E3 ubiquitin ligase complex that targets several substrates for ubiquitination and proteasomal degradation. Among these targets are the alpha-regulatory subunits of the hypoxia-inducible factor (HIF). VHL-/- cells constitutively overexpress hypoxia-inducible genes through both transcriptional and posttranscriptional mechanisms and form tumors when injected into nude mice. Reintroduction of pVHL into VHL-/- cell lines restores normal oxygen-dependent regulation of these genes and suppresses tumor formation in the mouse xenograft assay. We report here that short hairpin RNA-mediated inactivation of HIF phenocopies the effects of pVHL reintroduction with respect to decreased expression of hypoxia-inducible genes, decreased ability to promote vascular endothelial cell proliferation in vitro, and tumor growth suppression in vivo. In addition, HIF inactivation abrogated the cellular response to hypoxia, indicating that HIF is the only pVHL target required for this response. These data suggest that deregulation of hypoxia-inducible genes in VHL-/- cells can be attributed mainly to deregulation of HIF and validate HIF as a therapeutic anticancer drug target.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Animals
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Basic Helix-Loop-Helix Transcription Factors
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Carcinoma, Renal Cell / blood supply
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Carcinoma, Renal Cell / genetics
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Carcinoma, Renal Cell / metabolism
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Carcinoma, Renal Cell / pathology*
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Cell Division
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Cell Line, Tumor
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Endothelial Cells
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Gene Deletion
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Humans
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Hypoxia / metabolism
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Hypoxia / pathology
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Kidney Neoplasms / blood supply
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Kidney Neoplasms / genetics
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Kidney Neoplasms / metabolism
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Kidney Neoplasms / pathology*
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Mice
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Neovascularization, Pathologic
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Phenotype
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RNA Interference
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Trans-Activators / biosynthesis
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Trans-Activators / deficiency*
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Trans-Activators / genetics
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Tumor Suppressor Proteins / deficiency*
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Tumor Suppressor Proteins / genetics
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Tumor Suppressor Proteins / metabolism
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Ubiquitin-Protein Ligases / deficiency*
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Ubiquitin-Protein Ligases / genetics
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Ubiquitin-Protein Ligases / metabolism
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Umbilical Veins
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Vascular Endothelial Growth Factor A / analysis
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Vascular Endothelial Growth Factor A / biosynthesis
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Von Hippel-Lindau Tumor Suppressor Protein
Substances
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Basic Helix-Loop-Helix Transcription Factors
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Trans-Activators
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Tumor Suppressor Proteins
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VEGFA protein, human
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Vascular Endothelial Growth Factor A
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endothelial PAS domain-containing protein 1
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Ubiquitin-Protein Ligases
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Von Hippel-Lindau Tumor Suppressor Protein
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VHL protein, human