Z Gastroenterol 2015; 53 - A4_33
DOI: 10.1055/s-0034-1397185

Methylome screen identifies epigenetically deregulated microRNAs in cholangiocarcinoma

B Goeppert 1, C Ernst 2, C Baer 2, A Mehrabi 3, M Hafezi 3, M Renner 1, A Warth 1, A Stenzinger 1, W Weichert 1, P Schirmacher 1, C Plass 2, D Weichenhan 2
  • 1Heidelberg University Hospital, Institute of Pathology, Heidelberg, Germany
  • 2German Cancer Research Center (DKFZ), Division of Epigenomics and Cancer Risk Factors, Heidelberg, Germany
  • 3Heidelberg University Hospital, Department of General, Visceral, and Transplantation Surgery, Heidelberg, Germany

Background & Aims: The molecular mechanisms, in particular epigenetic alterations, underlying the genesis of cholangiocarcinomas (CC) are poorly understood. We have previously shown data of global methylation changes in CC. Here, we focus on specific microRNAs (miRNAs) that showed drastic methylation alterations in our methylome screen.

Methods: Data of a previously presented genome-wide analysis that identified differentially methylated regions (DMRs) in 18 human CCs were used. Candidate miRNAs were selected by a previously described in silico analysis and technically confirmed by quantitative MassARRAY® analysis. MiRNA expression was examined in formalin-fixed-paraffin-embedded material of tumor specimen (n= 20) and normal biliary epithelium (n= 20) and functional experiments were performed in vitro using two CC cell lines (TFK-1 and EGI-1).

Results: In silico analysis of global methylation data in CC identified large numbers of CC-related hypermethylated and hypomethylated miRNA promoters which were exemplarily confirmed in a second patient cohort. Inverse correlation between promoter methylation and expression suggests miR-129 – 2 and members of the miR-200 family, miR-200a, miR-200b and miR-429, as novel tumor suppressors and oncomiRs in CC, respectively. Reporter assays revealed the tumor suppressive genes DLC1 (deleted in liver cancer 1), FBXW7 (F-box/WD-repeat-containing protein 7) and CDH6 (cadherin-6) as presumed targets in CC.

Conclusions: Data of the genome-wide methylation landscape of CC revealed specific changes in the methylation pattern of miRNAs. Herein, we could present specific miRNAs as putative novel tumor suppressors and oncomiRs in CC. Furthermore we offer a valuable repository enabling to study the role of epigenetically altered miRNAs in the onset and progression of CC.

Corresponding author: Goeppert, Benjamin

E-Mail: benjamin.goeppert@med.uni-heidelberg.de