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Gastroenterology Research and Practice
Volume 2017 (2017), Article ID 3804146, 9 pages
https://doi.org/10.1155/2017/3804146
Research Article

The Methylation Status and Expression of Epstein-Barr Virus Early Genes BARF1 and BHRF1 in Epstein-Barr Virus-Associated Gastric Carcinomas

1Department of Clinical Laboratory, The Affiliated Hospital of Qingdao University, 19 Jiangsu Road, Qingdao 266003, China
2Department of Medical Microbiology, Qingdao University Medical College, 38 Dengzhou Road, Qingdao 266021, China
3Department of Central Laboratory, The Affiliated Hospital of Qingdao University, 19 Jiangsu Road, Qingdao 266003, China
4Department of Clinical Laboratory, Zibo Central Hospital, 19 Gongqingtuan Road, Zibo 255036, China

Correspondence should be addressed to Bing Luo; moc.361@gnibouldq

Received 31 December 2016; Revised 1 March 2017; Accepted 8 March 2017; Published 11 April 2017

Academic Editor: Haruhiko Sugimura

Copyright © 2017 Jing Li et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Epstein-Barr virus (EBV) is an important DNA virus which establishes latent infection in human malignancies. Expression of EBV-encoded genes in the associated tumors is strongly modulated by promoter CpG methylation of EBV genome. This study aimed to explore the methylation status of the promoters of EBV BamHI-A rightward frame 1 (BARF1) and BamHI-H rightward open reading frame 1 (BHRF1) and their influence on transcriptional expression, to further understand the roles of BARF1 and BHRF1 in the occurrence of EBV-associated cancer. We evaluated the methylation status of BARF1 and BHRF1 promoters in 43 EBV-associated gastric carcinoma (EBVaGC) tissues and EBV-positive cell lines. Their expressions were evaluated by real-time quantitative PCR. We found that the promoters of BARF1 and BHRF1 were methylated by varying degrees in different EBV-positive cell lines and were almost hypermethylated in all EBVaGC tissues. The methylation status of BARF1 and BHRF1 promoters were significantly reduced by 5-Aza-CdR along with the increasing gene expressions. Hypermethylation of Ap and Hp mediates the frequent silencing of BARF1 and BHRF1 in EBV-associated tumors, which could be reactivated by a demethylation agent, suggesting that promoter demethylation and activation is important for BARF1 and BHRF1 transcription and their further action.