Original Article
Copyright ©2011 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Gastroenterol. Aug 7, 2011; 17(29): 3407-3419
Published online Aug 7, 2011. doi: 10.3748/wjg.v17.i29.3407
Identification of methylation profile of HOX genes in extrahepatic cholangiocarcinoma
Yi Shu, Bing Wang, Ji Wang, Jian-Ming Wang, Sheng-Quan Zou
Yi Shu, Bing Wang, Ji Wang, Jian-Ming Wang, Sheng-Quan Zou, General Surgery Department of Tongji Hospital, Tongji Medical College of Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan 430030, Hubei Province, China
Author contributions: Shu Y conducted the Methyl-DNA immunoprecipitation, bisulfite-PCR, treatment with 5-Aza-2’-deoxycytidine and statistical analysis and drafted the manuscript; Wang B did immunofluorescence assays, statistical analysis and drafted the manuscript; Wang J and Wang JM participated in the statistical analysis and drafted the manuscript. Zou SQ conceived and designed the studies; all authors discussed the results, commented on the manuscript, read and approved the final manuscript.
Supported by The grant for “Development of Novel Nano-Drug Delivery System Loaded with Traditional Chinese Anticancer Medicine for the Targeted Therapy of Malignant Tumors” issued by the Chinese Ministry of Science and Technology, Grant No. 2010DFA31870
Correspondence to: Sheng-Quan Zou, Professor, General Surgery Department of Tongji Hospital, Tongji Medical College of Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan 430030, Hubei Province, China. sqzou05@yahoo.com.cn
Telephone: +86-27-83662688 Fax: +86-27-83662398
Received: March 11, 2011
Revised: May 17, 2011
Accepted: May 24, 2011
Published online: August 7, 2011
Abstract

AIM: To identify methylation profile and novel tumor marker of extrahepatic cholangiocarcinoma (CCA) with high throughout microarray.

METHODS: Differential methylation profile was compared between normal bile duct epithelial cell lines and CCA cell lines by methyl-DNA immunoprecipitation (MeDIP) microarray. Bisulfite-polymerase chain reaction (BSP) was performed to identify the methylated allels of target genes. Expression of target genes was investigated before and after the treatment with DNA demethylating agent. Expression of candidate genes was also evaluated by immunofluorescence in 30 specimens of CCA tissues and 9 normal bile duct tissues.

RESULTS: Methylation profile of CCA was identified with MeDIP microarray in the respects of different gene functions and signaling pathways. Interestingly, 97 genes with hypermethylated CpG islands in the promoter region were homeobox genes. The top 5 hypermethylated homeobox genes validated by BSP were HOXA2 (94.29%), HOXA5 (95.38%), HOXA11 (91.67%), HOXB4 (90.56%) and HOXD13 (94.38%). Expression of these genes was reactivated with 5’-aza-2’-deoxycytidine. Significant expression differences were found between normal bile duct and extrahepatic CCA tissues (66.67%-100% vs 3.33%-10%).

CONCLUSION: HOXA2, HOXA5, HOXA11, HOXB4 and HOXD13 may work as differential epigenetic biomarkers between malignant and benign biliary tissues.

Keywords: DNA methylation; Epigenetic; Promoter microarray; Cholangiocarcinoma