Original Article
Copyright ©2012 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Gastroenterol. Aug 7, 2012; 18(29): 3849-3861
Published online Aug 7, 2012. doi: 10.3748/wjg.v18.i29.3849
Mutual regulation between microRNA-373 and methyl-CpG-binding domain protein 2 in hilar cholangiocarcinoma
Yong-Jun Chen, Jian Luo, Guang-Yao Yang, Kang Yang, Song-Qi Wen, Sheng-Quan Zou
Yong-Jun Chen, Jian Luo, Guang-Yao Yang, Kang Yang, Song-Qi Wen, Sheng-Quan Zou, Department of Biliary-pancreatic Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, Hubei Province, China
Author contributions: Chen YJ and Zou SQ designed the research; Chen YJ, Luo L, Yang GY, Yang K and Wen SQ performed the research and analyzed the data; Chen YJ wrote the paper.
Supported by National Natural Science Foundation of China, No. 81071998; Hubei Natural Science Foundation, No. 2008CDB159; Specialized Research Fund for the Doctoral Program of Higher Education, No. 20070487114
Correspondence to: Yong-Jun Chen, MD, PhD, Associate Professor, Department of Biliary-pancreatic Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Ave, Wuhan 430030, Hubei Province, China. chenyongjun45@126.com
Telephone: +86-27-83663815 Fax: +86-27-83662398
Received: October 21, 2011
Revised: May 2, 2012
Accepted: May 5, 2012
Published online: August 7, 2012
Abstract

AIM: To investigate the reciprocal modulation between microRNA (miRNA) and DNA methylation via exploring the correlation between miR-373 and methyl-CpG-binding domain protein (MBD)2.

METHODS: MiR-373 expression was examined using the TaqMan miRNA assay. Methylation of miR-373 was investigated using methylation-specific polymerase chain reaction, and recruitment of methyl binding proteins was studied using the chromatin immunoprecipitation assay. Mutation analysis was conducted using the QuikChange™ Site-Directed Mutagenesis kit. The activity of miR-373 gene promoter constructs and targeting at MBD2-three prime untranslated region (3’UTR) by miR-373 were evaluated by a dual-luciferase reporter gene assay.

RESULTS: In hilar cholangiocarcinoma, miR-373 decreased and was closely associated with poor cell differentiation, advanced clinical stage, and shorter survival. The promoter-associated CpG island of miR-373 gene was hypermethylated and inhibited expression of miR-373. MBD2 was up-regulated and enriched at the promoter-associated CpG island of miR-373. Methylation-mediated suppression of miR-373 required MBD2 enrichment at the promoter-associated CpG island, and miR-373 negatively regulated MBD2 expression through targeting the 3’UTR.

CONCLUSION: MiR-373 behaves as a direct transcriptional target and negative regulator of MBD2 activity through a feedback loop of CpG island methylation.

Keywords: MicroRNA-373; Methyl-CpG binding domain proteins 2; Methylation; Hilar cholangiocarcinoma; Three prime untranslated region