Epigenetic regulation of vascular endothelial growth factor a dynamic expression in transitional cell carcinoma

Authors

  • Szu-Yuan Ping,

    1. Graduate Institute of Life Science, National Defense Medical Center, Taipei, Taiwan, Republic of China
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  • Kun-Hung Shen,

    1. Division of Urology, Departments of Surgery, Chi-Mei Medical Center, Tainan, Taiwan, Republic of China
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  • Dah-Shyong Yu

    Corresponding author
    1. Uro-Oncology Laboratory, Division of Urology, Department of Surgery, Tri-Service General Hospital and Institute of Preventive Medicine, National Defense Medical Center, Taipei, Taiwan, Republic of China
    • Tri-Service General Hospital, No. 325, Sec. 2, Cheng-Gung Rd, Nei-Hu, Taipei, Taiwan 114, Republic of China.
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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. © 2012 Wiley Periodicals, Inc.

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