title: Activation of vascular endothelial growth factor A transcription in tumorigenic glioblastoma cell lines by an enhancer with cell type-specific DNase I accessibility.
abstract: Unregulated expression of vascular endothelial growth factor-A (VEGF-A) plays an important role in tumor growth. We have identified a cell type-specific enhancer, HS-1100, that contributes to VEGF-A transcriptional activation in tumorigenic glioblastoma cell lines. This enhancer exhibits increased accessibility to DNase I in glioblastoma cell lines that express high levels of VEGF-A but not in several other cell lines that express much lower levels of VEGF-A. HS-1100 contains a number of sequence elements that are highly conserved among human, mouse, and rat, including the hypoxia-response element (HRE). We show that the HRE contributes significantly to the cell type-specific enhancer activity of HS-1100 in U87MG glioblastoma cells. We use chromatin immunoprecipitation assays to show that endothelial PAS domain protein 1 (EPAS1) can efficiently bind to the endogenous HRE in U87MG cells but not in HEK293 cells in which the chromosomal HS-1100 is not accessible to DNase I. A dominant negative EPAS1 significantly reduces HS-1100 enhancer activity and VEGF-A levels in U87MG cells. Our results provide insight into the molecular mechanisms of VEGF-A up-regulation during cancer development.
authors.affiliation: Sangamo BioSciences Incorporated, Richmond, California 94804, USA.
authors.forename: Yuxin
authors.initials: Y
authors.lastname: Liang
authors.forename: Xiao-Yong
authors.initials: XY
authors.lastname: Li
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Rebar
authors.forename: Peixiang
authors.initials: P
authors.lastname: Li
authors.forename: Yuanyue
authors.initials: Y
authors.lastname: Zhou
authors.forename: Bingliang
authors.initials: B
authors.lastname: Chen
authors.forename: Alan P
authors.initials: AP
authors.lastname: Wolffe
authors.forename: Casey C
authors.initials: CC
authors.lastname: Case
mesh_terms: D001483:Base Sequence; D051792:Basic Helix-Loop-Helix Proteins; D015153:Blotting, Western; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D002843:Chromatin / Q000378:metabolism; D003850:Deoxyribonuclease I / Q000378:metabolism*; D016228:Endothelial Growth Factors / Q000378:metabolism*; D005799:Genes, Dominant; D006801:Humans; D008156:Luciferases / Q000378:metabolism; D008969:Molecular Sequence Data; D009447:Neuroblastoma / Q000378:metabolism*; D011233:Precipitin Tests; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015534:Trans-Activators / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection; D014407:Tumor Cells, Cultured; D015854:Up-Regulation; D042461:Vascular Endothelial Growth Factor A; D000099162:Endothelial PAS Domain-Containing Protein 1
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D002843:Chromatin; D003850:Deoxyribonuclease I; D016228:Endothelial Growth Factors; D008156:Luciferases; D012333:RNA, Messenger; D015534:Trans-Activators; D042461:Vascular Endothelial Growth Factor A; D000099162:Endothelial PAS Domain-Containing Protein 1