Open AccessMechanisms of Platelet-Activating Factor-induced Enhancement of VEGF Expression
Author(s) -
Han-A Kim,
Kook Heon Seo,
Yeong-Rim Kang,
Hyun-Mi Ko,
Kyoung-Jin Kim,
Hae-Kyong Back,
Hern-Ku Lee,
Suhn-Young Im
Publication year - 2011
Publication title -
cellular physiology and biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.486
H-Index - 87
eISSN - 1421-9778
pISSN - 1015-8987
DOI - 10.1159/000325205
Subject(s) - transfection , luciferase , microbiology and biotechnology , downregulation and upregulation , vascular endothelial growth factor , immunoprecipitation , electrophoretic mobility shift assay , reporter gene , chemistry , cell culture , expression vector , vascular endothelial growth factor a , biology , gene expression , cancer research , vegf receptors , gene , biochemistry , recombinant dna , genetics
It has been previously reported that platelet-activating factor (PAF) induces the expression of vascular endothelial growth factor (VEGF) via the downregulation of p53 activity. In this study, we attempted to characterize the mechanism by which p53 activity negatively regulates PAF-induced VEGF expression. PAF increased luciferase activity as well as VEGF mRNA expression in human non-small cell lung cancer cell line H1299 transfected with VEGF luciferase reporter plasmid (VEGF-Luc). Cotransfection of the cells with wt p53, but not mutant p53, effected a blockage of PAF-induced VEGF mRNA expression. The ChIP assay revealed that p53 did not bind to the VEGF promoter. Transfection of Egr-1 or Sp-1 expression vector increased VEGF luciferase activity in VEGF-Luc-transfected cells, and this was inhibited by transfection with wt p53. The results of the Immunoprecipitation and immunoblot analysis showed that p53 binds to Egr-1 and Sp-1. Additionally, our electrophoretic mobility shift assay demonstrated that PAF induced the mobilization of Egr-1 and Sp-1 to the nucleus, and this activity was inhibited by transfection with wt p53. These data indicate that PAF inhibits protein complexes between p53 and Egr-1/Sp-1 via the downregulation of p53 levels, thus increasing the free form levels of Egr-1 and Sp-1, ultimately resulting in the transcriptional activation of VEGF.