title: Epigenetic regulation of vascular endothelial growth factor a dynamic expression in transitional cell carcinoma.
abstract: 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.
authors.affiliation: Graduate Institute of Life Science, National Defense Medical Center, Taipei, Taiwan, Republic of China.
authors.forename: Szu-Yuan
authors.initials: SY
authors.lastname: Ping
authors.forename: Kun-Hung
authors.initials: KH
authors.lastname: Shen
authors.forename: Dah-Shyong
authors.initials: DS
authors.lastname: Yu
mesh_terms: D015153:Blotting, Western; D002295:Carcinoma, Transitional Cell / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D047369:Chromatin Immunoprecipitation; D019175:DNA Methylation; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D057890:Epigenomics; D015972:Gene Expression Regulation, Neoplastic; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology; D006801:Humans; D060787:Neoplasm Grading; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured; D001749:Urinary Bladder Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics* / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; D056572:Histone Deacetylase Inhibitors; C489325:MBD2 protein, human; D012333:RNA, Messenger; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A