title: Repression of vascular endothelial growth factor A in glioblastoma cells using engineered zinc finger transcription factors.
abstract: Angiogenic factors are necessary for tumor proliferation and thus are attractive therapeutic targets. In this study, we have used engineered zinc finger protein (ZFP) transcription factors (TFs) to repress expression of vascular endothelial growth factor (VEGF)-A in human cancer cell lines. We create potent transcriptional repressors by fusing a designed ZFP targeted to the VEGF-A promoter with either the ligand-binding domain of thyroid hormone receptor alpha or its viral relative, vErbA. Moreover, this ZFP-vErbA repressor binds its intended target site in vivo and mediates the specific deacetylation of histones H3 and H4 at the targeted promoter, a result that emulates the natural repression mechanism of these domains. The potential therapeutic relevance of ZFP-mediated VEGF-A repression was addressed using the highly tumorigenic glioblastoma cell line U87MG. Despite the aberrant overexpression of VEGF-A in this cell line, engineered ZFP TFs were able to repress the expression of VEGF-A by >20-fold. The VEGF-A levels observed after ZFP TF-mediated repression were comparable to those of a nonangiogenic cancer line (U251MG), suggesting that the degree of repression obtained with the ZFP TF would be sufficient to suppress tumor angiogenesis. Thus, engineered ZFP TFs are shown to be potent regulators of gene expression with therapeutic promise in the treatment of disease.
authors.affiliation: Sangamo BioSciences, Inc., Richmond, California 94841, USA.
authors.forename: Andrew W
authors.initials: AW
authors.lastname: Snowden
authors.forename: Lei
authors.initials: L
authors.lastname: Zhang
authors.forename: Fyodor
authors.initials: F
authors.lastname: Urnov
authors.forename: Carolyn
authors.initials: C
authors.lastname: Dent
authors.forename: Yann
authors.initials: Y
authors.lastname: Jouvenot
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Zhong
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Rebar
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Jamieson
authors.forename: H Steven
authors.initials: HS
authors.lastname: Zhang
authors.forename: Siyuan
authors.initials: S
authors.lastname: Tan
authors.forename: Casey C
authors.initials: CC
authors.lastname: Case
authors.forename: Carl O
authors.initials: CO
authors.lastname: Pabo
authors.forename: Alan P
authors.initials: AP
authors.lastname: Wolffe
authors.forename: Philip D
authors.initials: PD
authors.lastname: Gregory
mesh_terms: D045744:Cell Line, Tumor; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics; D005909:Glioblastoma / Q000098:blood supply / Q000235:genetics / Q000378:metabolism* / Q000628:therapy*; D006801:Humans; D009389:Neovascularization, Pathologic / Q000235:genetics / Q000378:metabolism; D018774:Oncogene Proteins v-erbA / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014162:Transfection; D042461:Vascular Endothelial Growth Factor A / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000235:genetics; D016335:Zinc Fingers / Q000235:genetics*
chemical_list: D004268:DNA-Binding Proteins; D018774:Oncogene Proteins v-erbA; D014157:Transcription Factors; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A