Role of microRNA-155 at early stages of hepatocarcinogenesis induced by choline-deficient and amino acid-defined diet in C57BL/6 mice

Hepatology. 2009 Oct;50(4):1152-61. doi: 10.1002/hep.23100.

Abstract

MicroRNAs (miRs) are conserved, small (20-25 nucleotide) noncoding RNAs that negatively regulate expression of messenger RNAs (mRNAs) at the posttranscriptional level. Aberrant expression of certain microRNAs plays a causal role in tumorigenesis. Here, we report identification of hepatic microRNAs that are dysregulated at early stages of feeding C57BL/6 mice choline-deficient and amino acid-defined (CDAA) diet that is known to promote nonalcoholic steatohepatitis (NASH)-induced hepatocarcinogenesis after 84 weeks. Microarray analysis identified 30 hepatic microRNAs that are significantly (P < or = 0.01) altered in mice fed CDAA diet for 6, 18, 32, and 65 weeks compared with those fed choline-sufficient and amino acid-defined (CSAA) diet. Real-time reverse transcription polymerase chain reaction (RT-PCR) analysis demonstrated up-regulation of oncogenic miR-155, miR-221/222, and miR-21 and down-regulation of the most abundant liver-specific miR-122 at early stages of hepatocarcinogenesis. Western blot analysis showed reduced expression of hepatic phosphatase and tensin homolog (PTEN) and CCAAT/enhancer binding protein beta (C/EBPbeta), respective targets of miR-21 and miR-155, in these mice at early stages. DNA binding activity of nuclear factor kappa B (NF-kappaB) that transactivates miR-155 gene was significantly (P = 0.002) elevated in the liver nuclear extract of mice fed CDAA diet. Furthermore, the expression of miR-155, as measured by in situ hybridization and real-time RT-PCR, correlated with diet-induced histopathological changes in the liver. Ectopic expression of miR-155 promoted growth of hepatocellular carcinoma (HCC) cells, whereas its depletion inhibited cell growth. Notably, miR-155 was significantly (P = 0.0004) up-regulated in primary human HCCs with a concomitant decrease (P = 0.02) in C/EBPbeta level compared with matching liver tissues.

Conclusion: Temporal changes in microRNA profile occur at early stages of CDAA diet-induced hepatocarcinogenesis. Reciprocal regulation of specific oncomirs and their tumor suppressor targets implicate their role in NASH-induced hepatocarcinogenesis and suggest their use in the diagnosis, prognosis, and therapy of liver cancer.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Amino Acids / metabolism*
  • Animals
  • CCAAT-Enhancer-Binding Protein-beta / metabolism
  • Carcinoma, Hepatocellular / etiology
  • Carcinoma, Hepatocellular / metabolism*
  • Carcinoma, Hepatocellular / pathology
  • Cell Line, Tumor
  • Cell Proliferation
  • Choline Deficiency / metabolism*
  • Disease Models, Animal
  • Fatty Liver / complications*
  • Humans
  • Liver / metabolism
  • Liver / pathology
  • Liver Neoplasms / etiology
  • Liver Neoplasms / metabolism*
  • Liver Neoplasms / pathology
  • Membrane Proteins
  • Mice
  • Mice, Inbred C57BL
  • MicroRNAs / metabolism*
  • NF-kappa B / metabolism
  • PTEN Phosphohydrolase / metabolism

Substances

  • Amino Acids
  • CCAAT-Enhancer-Binding Protein-beta
  • MIRN155 microRNA, human
  • Membrane Proteins
  • MicroRNAs
  • Mirn122 microRNA, mouse
  • Mirn155 microRNA, mouse
  • NF-kappa B
  • Usmg5 protein, rat
  • PTEN Phosphohydrolase
  • Pten protein, mouse