Abstract
Hypoxia-inducible factors (HIFs) are highly conserved transcription factors that play a crucial role in oxygen homeostasis. Intratumoral hypoxia and genetic alterations lead to HIF activity, which is a hallmark of solid cancer and is associated with poor clinical outcome. HIF activity is regulated by an evolutionary conserved mechanism involving oxygen-dependent HIFalpha protein degradation. To identify novel components of the HIF pathway, we performed a genome-wide RNA interference screen in Caenorhabditis elegans, to suppress HIF-dependent phenotypes, like egg-laying defects and hypoxia survival. In addition to hif-1 (HIFalpha) and aha-1 (HIFbeta), we identified hlh-8, gska-3 and spe-8. The hlh-8 gene is homologous to the human oncogene TWIST1. We show that TWIST1 expression in human cancer cells is enhanced by hypoxia in a HIF-2alpha-dependent manner. Furthermore, intronic hypoxia response elements of TWIST1 are regulated by HIF-2alpha, but not HIF-1alpha. These results identify TWIST1 as a direct target gene of HIF-2alpha, which may provide insight into the acquired metastatic capacity of hypoxic tumors.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Basic Helix-Loop-Helix Transcription Factors / physiology*
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Blotting, Western
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Caenorhabditis elegans / genetics
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Caenorhabditis elegans / growth & development
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Caenorhabditis elegans / metabolism
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Caenorhabditis elegans Proteins / genetics
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Caenorhabditis elegans Proteins / metabolism
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Cell Hypoxia*
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Cells, Cultured
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Deferoxamine / pharmacology
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Gene Expression Regulation*
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Genome
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HeLa Cells
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Humans
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Hypoxia-Inducible Factor 1, alpha Subunit / genetics
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Hypoxia-Inducible Factor 1, alpha Subunit / metabolism
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Nuclear Proteins / metabolism*
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Procollagen-Proline Dioxygenase / antagonists & inhibitors
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Procollagen-Proline Dioxygenase / metabolism
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RNA, Messenger / metabolism
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RNA, Small Interfering / genetics
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RNA, Small Interfering / metabolism*
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Repressor Proteins / genetics
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Repressor Proteins / metabolism
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Response Elements
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Transcription, Genetic
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Transcriptional Activation
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Transfection
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Twist-Related Protein 1 / metabolism*
Substances
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Basic Helix-Loop-Helix Transcription Factors
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Caenorhabditis elegans Proteins
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HIF1A protein, human
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Hypoxia-Inducible Factor 1, alpha Subunit
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Nuclear Proteins
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RNA, Messenger
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RNA, Small Interfering
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Repressor Proteins
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TWIST1 protein, human
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Twist-Related Protein 1
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endothelial PAS domain-containing protein 1
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Procollagen-Proline Dioxygenase
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Deferoxamine