1. Sp1 Is Involved in Akt-mediated Induction of VEGF Expression through an HIF-1–independent Mechanism
- Author
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Hui-Kuo G. Shu, Nabendu Pore, Gilles Pagès, Donald M. O'Rourke, Amit Maity, Bin Li, Eric J. Bernhard, Julie Milanini-Mongiat, Shuang Liu, David Stokoe, Daphne A. Haas-Kogan, Dept. of Radiation Oncology, University of Pennsylvania, University of Pennsylvania [Philadelphia], Dept. of Radiation Oncology, UCSF, University of California [San Francisco] (UCSF), University of California-University of California, Cancer Research Institute, UCSF, Institut de signalisation, biologie du développement et cancer (ISBDC), Centre National de la Recherche Scientifique (CNRS)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA), and Dept. of Neurosurgery, University of Pennsylvania
- Subjects
Small interfering RNA ,MESH: Ketones ,MESH: Base Sequence ,MESH: Animal Nutrition Physiology ,0302 clinical medicine ,Genes, Reporter ,MESH: Up-Regulation ,MESH: Animals ,Hypoxia ,0303 health sciences ,Neovascularization, Pathologic ,MESH: Laminin ,MESH: Diffusion ,MESH: Adenoviridae ,MESH: Transcription Factors ,Up-Regulation ,MESH: Promoter Regions (Genetics) ,Drug Combinations ,Vascular endothelial growth factor A ,MESH: Proteoglycans ,030220 oncology & carcinogenesis ,MESH: Feeding Behavior ,RNA Interference ,MESH: Exploratory Behavior ,Collagen ,Hypoxia-Inducible Factor 1 ,Transcriptional Activation ,Blotting, Western ,Molecular Sequence Data ,MESH: Plicamycin ,Transfection ,Adenoviridae ,MESH: Soil ,03 medical and health sciences ,MESH: Green Fluorescent Proteins ,MESH: Plasmids ,MESH: Blotting, Northern ,MESH: Blotting, Western ,MESH: Protein Binding ,Humans ,Molecular Biology ,Protein kinase B ,MESH: Sp1 Transcription Factor ,MESH: Drug Combinations ,MESH: Humans ,MESH: Molecular Sequence Data ,MESH: Phosphorylation ,MESH: Magnetic Resonance Spectroscopy ,MESH: Vascular Endothelial Growth Factor A ,MESH: Genes, Reporter ,MESH: Homing Behavior ,[SDV.BBM.BM]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Molecular biology ,MESH: Cell Line ,MESH: Hypoxia-Inducible Factor 1 ,MESH: Binding Sites ,chemistry ,Laminin ,MESH: Chromatography, Liquid ,MESH: Nuclear Proteins ,Densitometry ,Transcription Factors ,Vascular Endothelial Growth Factor A ,Angiogenesis ,MESH: Densitometry ,MESH: Anoxia ,MESH: Solvents ,MESH: Vascular Endothelial Growth Factors ,Phosphatidylinositol 3-Kinases ,Transactivation ,chemistry.chemical_compound ,MESH: Alkaline Phosphatase ,MESH: Collagen ,MESH: Reverse Transcriptase Polymerase Chain Reaction ,MESH: RNA, Small Interfering ,Epidermal growth factor receptor ,Phosphorylation ,RNA, Small Interfering ,Promoter Regions, Genetic ,Reverse Transcriptase Polymerase Chain Reaction ,Nuclear Proteins ,Articles ,Plicamycin ,DNA-Binding Proteins ,Vascular endothelial growth factor ,MESH: Phosphates ,Proteoglycans ,Plasmids ,Protein Binding ,MESH: Sodium Chloride ,MESH: Cell Line, Tumor ,Sp1 Transcription Factor ,MESH: RNA Interference ,Green Fluorescent Proteins ,[SDV.CAN]Life Sciences [q-bio]/Cancer ,Biology ,MESH: Hypoxia-Inducible Factor 1, alpha Subunit ,MESH: Hydrocarbons, Aromatic ,Cell Line ,Phosphates ,MESH: Diet ,Cell Line, Tumor ,MESH: Thailand ,PI3K/AKT/mTOR pathway ,030304 developmental biology ,Binding Sites ,Base Sequence ,MESH: Transcription, Genetic ,MESH: Transfection ,MESH: 1-Phosphatidylinositol 3-Kinase ,Cell Biology ,Alkaline Phosphatase ,Blotting, Northern ,Hypoxia-Inducible Factor 1, alpha Subunit ,MESH: Colobinae ,MESH: Trans-Activation (Genetics) ,Cancer research ,biology.protein ,MESH: Neovascularization, Pathologic ,MESH: DNA-Binding Proteins - Abstract
International audience; Increased expression of vascular endothelial growth factor (VEGF) contributes to the growth of many tumors by increasing angiogenesis. Although hypoxia is a potent inducer of VEGF, we previously showed that epidermal growth factor receptor amplification and loss of PTEN, both of which can increase phosphatidylinositol-3-kinase (PI3K) activity, increase VEGF expression. Using both adenoviral vectors and a cell line permanently expressing constitutively active myristoylated Akt (myrAkt), we show that activation of Akt, which is downstream of PI3K, increases VEGF expression in vitro and increases angiogenesis in a Matrigel plug assay. Transient transfection experiments using reporter constructs containing the VEGF promoter showed that up-regulation of VEGF by Akt is mediated through Sp1 binding sites located in the proximal promoter. Small interfering RNA directed against Sp1 prevented the induction of VEGF mRNA in response to myrAkt but not to hypoxia. Expression of myrAkt is associated with increased phosphorylation of Sp1 and its increased binding to a probe corresponding to the -88/-66 promoter region. In conclusion, our results indicate that Sp1 is required for transactivation of the VEGF by Akt. Others have proposed that the PI3K/Akt pathway can increase VEGF expression via the hypoxia-inducible factor 1 (HIF-1); however, our results suggest an alternative mechanism can also operate.
- Published
- 2004