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Epigenetic regulation of vascular endothelial growth factor a dynamic expression in transitional cell carcinoma
Author(s) -
Ping SzuYuan,
Shen KunHung,
Yu DahShyong
Publication year - 2013
Publication title -
molecular carcinogenesis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.254
H-Index - 97
eISSN - 1098-2744
pISSN - 0899-1987
DOI - 10.1002/mc.21892
Subject(s) - biology , dna methylation , cancer research , vascular endothelial growth factor , microbiology and biotechnology , chromatin immunoprecipitation , epigenetics , bisulfite sequencing , histone deacetylase inhibitor , cpg site , angiogenesis , histone , histone deacetylase , gene expression , promoter , gene , vegf receptors , biochemistry
Vascular endothelial growth factor A (VEGF‐A) is a key mediator in the neovascularization of cancers. We have found that VEGF‐A was expressed at significantly higher levels in high‐grade transitional cell carcinoma (TCC) cells than low‐grade TCC cells in our previous study. In the present study, promoter methylation pattern was assessed and quantified by bisulfite genomic sequencing (BGS) and specific VEGF‐A CpG sites in low‐grade, but not in high‐grade, TCC cells were observed. Reporter assays indicated that hypermethylation of nine CpG sites can inhibit the transcriptional activity of the VEGF‐A gene. Subsequent chromatin immunoprecipitation (ChIP) assay revealed down‐regulation of transcription activity of VEGF‐A with increasing binding of methyl‐CpG‐binding protein 2 (MBD2) and trimethyl‐histone H3 (Lys9) proteins to these CpG sites in low‐grade TCC cells during hypermethylation. Furthermore, treatment of low‐grade TCC cells with DNA methyltransferase inhibitor and histone deacetylase inhibitor can restore the expression of VEGF‐A and promote the invasive ability of low‐grade TCC cells. Hypermethylation with lower expression levels of VEGF‐A in low‐grade TCC tumors than high‐grade TCC tumors was also confirmed in clinical specimens by reverse transcriptase‐PCR and pyrosequencing analyses. Our findings are the first results indicating that VEGF‐A expression is suppressed in low‐grade TCC tumors by promoter hypermethylation. This offers a new perspective on the role of VEGF‐A in TCC tumor behavior. © 2012 Wiley Periodicals, Inc.