Abstract 2433: Hepatitis B virus X protein induces metastasis-associated protein 1 gene expression through promoter methylation

Abstract

Abstract Expression of metastasis-associated protein 1 (mta1) gene is well correlated with the degree of invasion and lymphatic metastasis in colorectal, hepatocellular and breast carcinomas. Expression of MTA1 was induced by hepatitis B virus X protein (HBx), however, little is known about transcriptional regulation of mta1 gene expression. Here, we reported that 5′-flanking region of MTA1 promoter contains two CpG islands. CpG island 1 and CpG island 2. The CpG island 1 was highly methylated (32.5%) but CpG island 2 (<1%) was not. Using bisulfite-modified direct sequencing, transient expression of HBx led to an increase in methylation of the CpG island 1 up to 48.8 %. In addition, chromatin immunoprecipitation revealed that HBx recruited DNMT3A to CpG island 1 region of MTA1 promoter. In silico analysis of the CpG island 1 predicted an existence of putative p53 binding sequences. We demonstrated that p53 bound to the CpG island 1 by chromatin immunoprecipitation using specific anti-p53 antibody. Further, p53 was pull-downed by DNA probe encoding the p53 binding sequences. However p53 was not pull-downed by the methylated DNA probe using SssI DNA methyltransferase. These data showed that HBx induced methylation of CpG island 1, which interferes the DNA binding of p53 on the specific DNA region. This result may provide the molecular mechanism of how HBx induces the expression of MTA1 gene. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2433. doi:10.1158/1538-7445.AM2011-2433