Abstract
The aim of this paper was to study the molecular mechanisms by which bcl-2 increases hypoxia-induced vascular endothelial growth factor (VEGF) expression. We demonstrated that bcl-2 overexpression in M14 human melanoma cell line enhances hypoxia-induced VEGF mRNA stability and promoter activation. In particular, the half-life of the message was longer in bcl-2 transfectants (approximately 330 min) than in control cells (approximately 180 min). In addition, bcl-2 overexpression increased VEGF promoter activity through the hypoxia-inducible factor-1 (HIF-1) transcription factor. Increased HIF-1a protein expression and DNA binding activity were detected in bcl-2 overexpressing cells compared with control cells. An enhanced functional activity of secreted VEGF was found both in in vitro and in vivo angiogenic assays, and the use of VEGF specific antibodies validated the role of VEGF on bcl-2-induced angiogenesis. Taken together our results indicate that bcl-2 plays an important role in melanoma angiogenesis, and that VEGF mRNA stabilization and HIF-1-mediated transcriptional activity are two important control points in bcl-2/hypoxia-induced VEGF expression.
MeSH terms
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Animals
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Cell Hypoxia
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Chick Embryo
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DNA-Binding Proteins / physiology*
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Endothelial Growth Factors / genetics*
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Endothelial Growth Factors / metabolism
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Gene Expression Regulation, Neoplastic*
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Humans
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Hypoxia-Inducible Factor 1
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Hypoxia-Inducible Factor 1, alpha Subunit
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Lymphokines / genetics*
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Lymphokines / metabolism
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Melanoma / blood
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Melanoma / genetics*
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Melanoma / metabolism
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Models, Biological
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Neovascularization, Pathologic
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Neovascularization, Physiologic
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Nuclear Proteins / physiology*
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Promoter Regions, Genetic
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Proto-Oncogene Proteins c-bcl-2 / genetics
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Proto-Oncogene Proteins c-bcl-2 / metabolism
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Proto-Oncogene Proteins c-bcl-2 / physiology*
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RNA Stability*
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RNA, Messenger / metabolism
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Transcription Factors*
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Transcriptional Activation
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Transfection
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Tumor Cells, Cultured
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Vascular Endothelial Growth Factor A
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Vascular Endothelial Growth Factors
Substances
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DNA-Binding Proteins
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Endothelial Growth Factors
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HIF1A protein, human
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Hypoxia-Inducible Factor 1
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Hypoxia-Inducible Factor 1, alpha Subunit
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Lymphokines
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Nuclear Proteins
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Proto-Oncogene Proteins c-bcl-2
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RNA, Messenger
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Transcription Factors
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Vascular Endothelial Growth Factor A
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Vascular Endothelial Growth Factors