2). In Mz-ChA-1 cells, miR-148a expression was decreased to 0.25- ± 0.03-fold, and miR-152 expression was decreased to 0.23- ± 0.02-fold relative to H69 nonmalignant human cholangiocytes. Similar reductions in expression were also seen in malignant KMCH and TFK cells. The reduced expression of this group of miRNAs is consistent with increased expression of DNMT-1 in cholangiocarcinoma, see more and suggests that this group of miRNAs may be involved in deregulation of genomic methylation in human cholangiocarcinoma. A recent study of miRNA expression in intrahepatic cholangiocarcinoma samples showed reduced expression of miR-148a and miR-152 in cholangiocytes compared with normal liver tissues,20 but these were not aberrantly

expressed in malignant tissues. These Midostaurin manufacturer may reflect differences in anatomical site of origin between these tumors and the cell lines used in our study. Notably, miR-148a expression is reduced in metastatic hepatocellular carcinoma supporting its potential as an oncosuppressor RNA gene. Chromosomal aberrations in genomic regions encoding miRNAs could contribute to altered expression in tumors. In order to evaluate the relationship between chromosomal aberrations and miRNA expression in biliary cancers, we evaluated the frequency

of chromosomal loss in the regions corresponding to miR-130a (11q12.1), miR-130b (22q11.21), miR-148a (7p15.2), miR-152 (17q21.32), and miR-301 (17q22) in intrahepatic and extrahepatic cholangiocarcinoma, using a comprehensive cytogenetic database (http://www.progenetix.de/∼pgscripts/progenetix). Chromosomal losses were observed in 11% in the sites of miR-152 and miR-301 and in 22% in the site of miR-130a of extrahepatic bile ducts tumors, while no losses were detected for the location of miR-148a and miR-130b. In

intrahepatic bile duct tumors, losses in both sites of chromosome 17 were detected in 6%, while no losses were observed in the sites of miR-148a and miR-130a. The highest frequency (11.8%) of losses was observed much for the site of miR-130b. Analysis of chromosomal changes in Mz-ChA-1 using a bacterial artificial chromosome array comparative genomic hybridization analysis did not show any significant changes in copy number for clones encompassing the genomic site of these miRNAs. Thus, chromosomal alterations do not account for altered expression of these microRNAs in Mz-ChA-1 cells. To determine the role of this specific group of miRNAs on IL-6–mediated DNMT-1 expression, Mz-ChA-1 human cholangiocarcinoma cells were stably transfected to overexpress IL-6 (Mz-IL-6 cells). When implanted as xenografts in athymic nude mice, the growth rate of Mz-IL-6 xenografts was increased compared with Mz-1 control cell xenografts, in conjunction with a decrease in the number of TUNEL-positive (apoptotic) cells.3 We used an miRNA microarray to assess the expression of human miRNAs in Mz-IL-6 cell lines overexpressing IL-6 and in Mz-IL-6–derived xenografts.