Upregulation of DARS2 by HBV promotes hepatocarcinogenesis through the miR-30e-5p/MAPK/NFAT5 pathway

J Exp Clin Cancer Res. 2017 Oct 19;36(1):148. doi: 10.1186/s13046-017-0618-x.

Abstract

Background: Infection with the hepatitis B virus (HBV) is closely associated with the development of hepatocellular carcinoma (HCC). The osmoregulatory transcription factor nuclear factor of activated T-cells 5 (NFAT5) has been shown to play an important role in the development of many types of human cancers. The role of NFAT5 in HBV-associated HCC has never previously been investigated.

Methods: We compared expression profiles of NFAT5, DARS2 and miR-30e-5p in HCC samples, adjacent nontumor tissues and different hepatoma cell lines by quantitative real-time polymerase chain reaction and /or Western blot. Clinical data of HCC patients for up to 80 months were analyzed. The regulatory mechanisms upstream and convergent downstream pathways of NFAT5 in HBV-associated HCC were investigated by ChIP-seq, MSP, luciferase report assay and bioinformation anaylsis.

Results: We first found that higher levels of NFAT5 expression predict a good prognosis, suggesting that NFAT5 is a potential tumor-suppressing gene, and verified that NFAT5 promotes hepatoma cell apoptosis and inhibits cell growth in vitro. Second, our results showed that HBV could suppress NFAT5 expression by inducing hypermethylation of the AP1-binding site in the NFAT5 promoter in hepatoma cells. In addition, HBV also inhibited NFAT5 through miR-30e-5p targeted MAP4K4, and miR-30e-5p in turn inhibited HBV replication. Finally, we demonstrated that NFAT5 suppressed DARS2 by directly binding to its promoter. DARS2 was identified as an HCC oncogene that promotes HCC cell cycle progression and inhibits HCC cell apoptosis.

Conclusion: HBV suppresses NFAT5 through the miR-30e-5p/mitogen-activated protein kinase (MAPK) signaling pathway upstream of NFAT5 and inhibits the NFAT5 to enhance HCC tumorigenesis via the downstream target genes of DARS2.

Keywords: DARS2; HBV; Hepatocellular carcinoma; NFAT5; miR-30e-5p.

Publication types

  • Comparative Study

MeSH terms

  • Aspartate-tRNA Ligase / genetics*
  • Aspartate-tRNA Ligase / metabolism
  • Carcinoma, Hepatocellular / genetics
  • Carcinoma, Hepatocellular / metabolism
  • Carcinoma, Hepatocellular / virology*
  • Cell Line, Tumor
  • DNA Methylation
  • Female
  • Gene Expression Regulation, Neoplastic
  • Hep G2 Cells
  • Hepatitis B / genetics*
  • Hepatitis B / metabolism
  • Hepatitis B virus / physiology*
  • Humans
  • Liver Neoplasms / genetics
  • Liver Neoplasms / metabolism
  • Liver Neoplasms / virology*
  • Male
  • MicroRNAs / genetics*
  • Mitogen-Activated Protein Kinases / genetics
  • Mitogen-Activated Protein Kinases / metabolism
  • Prognosis
  • Promoter Regions, Genetic
  • Signal Transduction
  • Transcription Factors / genetics*
  • Transcription Factors / metabolism
  • Up-Regulation*
  • Virus Replication

Substances

  • MIRN30b microRNA, human
  • MicroRNAs
  • NFAT5 protein, human
  • Transcription Factors
  • Mitogen-Activated Protein Kinases
  • Aspartate-tRNA Ligase
  • DARS2 protein, human