MiRNA-17 encoded by the miR-17-92 cluster increases the potential for steatosis in hepatoma cells by targeting CYP7A1

Cell Mol Biol Lett. 2018 Apr 18:23:16. doi: 10.1186/s11658-018-0083-3. eCollection 2018.

Abstract

Background: The miRNA cluster miR-17-92 is known to act as an oncogene in various cancers. Members of this cluster were also found to be involved in some other pathological process, such as steatosis, which is a pivotal event in the initiation and progression of nonalcoholic fatty liver disease (NAFLD). This study aimed to explore whether miR-17, one of the most functional miRNAs in the miR-17-92 family, participates in the process of steatosis in hepatoma cells.

Methods: We developed both a miR-17-expressing transgenic mouse model and a miR-17-expressing HepG2 cell model, the latter was established via stable transfection. Real-time PCR and western blot were applied to measure the expression levels of miR-17 and the potential target gene CYP7A1. The luciferase assay was used to confirm direct binding of miR-17 and CYP7A1. The oleic acid induction assay and Oil-Red-O staining were performed to support the determination of steatotic changes in HepG2 cell.

Results: Extensive steatotic changes were observed in the livers of transgenic mice. Fewer were seen in the wild-type animals. CYP7A1 was confirmed as a target gene of miR-17, and the expression of CYP7A1 was found to be negatively regulated in both the transgenic mice liver cells and the miR-17-expressing HepG2 cells. CYP7A1 was found to participate in miR-17-induced steatosis, as its repressed expression in miR-17 HepG2 cells exacerbated steatotic change. Re-introduction of CYP7A1 into miR-17 HepG2 cell partially alleviated steatosis.

Conclusions: miR-17 is a novel regulator of CYP7A1 signaling in hepatic lipid metabolism, suggesting a potential therapeutic approach for fatty liver.

Keywords: CYP7A1; Fatty liver; MiRNA-17; Steatosis.

MeSH terms

  • Animals
  • Cholesterol 7-alpha-Hydroxylase / genetics
  • Cholesterol 7-alpha-Hydroxylase / metabolism*
  • Disease Models, Animal
  • Fatty Liver / chemically induced
  • Fatty Liver / genetics
  • Fatty Liver / metabolism*
  • Hep G2 Cells
  • Humans
  • Liver / pathology
  • Mice
  • Mice, Inbred C57BL
  • Mice, Transgenic
  • MicroRNAs / genetics*
  • MicroRNAs / metabolism*
  • Oleic Acid / pharmacology

Substances

  • MIRN17 microRNA, human
  • MicroRNAs
  • Mirn17 microRNA, mouse
  • Oleic Acid
  • CYP7A1 protein, human
  • Cholesterol 7-alpha-Hydroxylase
  • Cyp7a1 protein, mouse