MiR-376c down-regulation accelerates EGF-dependent migration by targeting GRB2 in the HuCCT1 human intrahepatic cholangiocarcinoma cell line

PLoS One. 2013 Jul 26;8(7):e69496. doi: 10.1371/journal.pone.0069496. Print 2013.

Abstract

MicroRNA miR-376c was expressed in normal intrahepatic biliary epithelial cells (HIBEpiC), but was significantly suppressed in the HuCCT1 intrahepatic cholangiocarcinoma (ICC) cell line. The biological significance of the down-regulation of miR-376c in HuCCT1 cells is unknown. We hypothesized that miR-376c could function as a tumor suppressor in these cells. To test this hypothesis, we sought the targets of miR-376c, and characterized the effect of its down-regulation on HuCCT1 cells. We performed proteomic analysis of miR-376c-overexpressing HuCCT1 cells to identify candidate targets of miR-376c, and validated these targets by 3'-UTR reporter assay. Transwell migration assays were performed to study the migratory response of HuCCT1 cells to miR-376c overexpression. Furthermore, microarrays were used to identify the signaling that were potentially involved in the miR-376c-modulated migration of HuCCT1. Finally, we assessed epigenetic changes within the potential promoter region of the miR-376c gene in these cells. Proteomic analysis and subsequent validation assays showed that growth factor receptor-bound protein 2 (GRB2) was a direct target of miR-376c. The transwell migration assay revealed that miR-376c significantly reduced epidermal growth factor (EGF)-dependent cell migration in HuCCT1 cells. DNA microarray and subsequent pathway analysis showed that interleukin 1 beta and matrix metallopeptidase 9 were possible participants in EGF-dependent migration of HuCCT1 cells. Bisulfite sequencing showed higher methylation levels of CpG sites upstream of the miR-376c gene in HuCCT1 relative to HIBEpiC cells. Combined treatment with the DNA-demethylating agent 5-aza-2'-deoxycytidine and the histone deacetylase inhibitor trichostatin A significantly upregulated the expression of miR-376c in HuCCT1 cells. We revealed that epigenetic repression of miR-376c accelerated EGF-dependent cell migration through its target GRB2 in HuCCT1 cells. These findings suggest that miR-376c functions as a tumor suppressor. Since metastasis is the major cause of death in ICC, microRNA manipulation could lead to the development of novel anti-cancer therapy strategies for ICC.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bile Duct Neoplasms / genetics
  • Bile Duct Neoplasms / pathology
  • Bile Ducts, Intrahepatic
  • Cell Line, Tumor
  • Cell Movement / drug effects
  • Cell Movement / genetics*
  • Cholangiocarcinoma / genetics*
  • Cholangiocarcinoma / pathology*
  • DNA Methylation / drug effects
  • DNA Methylation / genetics
  • Down-Regulation / drug effects
  • Down-Regulation / genetics*
  • Epidermal Growth Factor / pharmacology*
  • Epigenesis, Genetic / drug effects
  • GRB2 Adaptor Protein / metabolism*
  • Gene Expression Regulation, Neoplastic / drug effects
  • Gene Regulatory Networks / drug effects
  • Gene Regulatory Networks / genetics
  • Humans
  • Liver Neoplasms / genetics*
  • Liver Neoplasms / pathology*
  • MicroRNAs / genetics*
  • MicroRNAs / metabolism
  • Neoplasm Proteins / metabolism
  • Proteomics
  • Reproducibility of Results

Substances

  • GRB2 Adaptor Protein
  • GRB2 protein, human
  • MIRN376C microRNA, human
  • MicroRNAs
  • Neoplasm Proteins
  • Epidermal Growth Factor

Grants and funding

This work was supported by Grants-in-Aids for Scientific Research and Private University Strategic Research Foundation Support Program from the Ministry of Education, Culture, Sports, Science and Technology/Japan Society for the Promotion of Science, Japan. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.