Oncogenic miR-96-5p inhibits apoptosis by targeting the caspase-9 gene in hepatocellular carcinoma

Int J Oncol. 2018 Jul;53(1):237-245. doi: 10.3892/ijo.2018.4369. Epub 2018 Apr 12.

Abstract

The aberrant expression or alteration of microRNAs (miRNAs/miRs) contributes to the development and progression of cancer. In the present study, the functions of miR-96-5p in hepatocellular carcinoma (HCC) were investigated. It was identified that miR-96-5p expression was significantly upregulated in primary HCC tumors compared with their non-tumorous counterparts. A copy number gain was frequently observed at chromosomal region 7q32.2 in which the MIR96 locus is located, suggesting that gene amplification may be one of the mechanisms by which miR-96-5p expression is increased in HCC. Transfection of miR-96-5p mimic into HCC cells decreased the expression of CASP9, which encodes caspase-9, the essential initiator caspase in the mitochondrial apoptotic pathway, at the mRNA and protein levels. A putative binding site for miR-96-5p was identified in the CASP9 3'-untranslated region, and the results of a luciferase assay indicated that CASP9 is a potential direct target of miR-96-5p. The miR-96-5p mimic increased resistance to doxorubicin- and ultraviolet-induced apoptosis through the decrease in caspase-9 expression in HCC cells. Transfection of miR-96-5p inhibitor enhanced the cytotoxic effect of doxorubicin by increasing caspase-9 expression in the HCC cells, suggesting a synergistic effect between the miR-96-5p inhibitor and doxorubicin. In conclusion, the results of the present study suggest that miR-96-5p, which is frequently upregulated in HCC, inhibits apoptosis by targeting CASP9. Therefore, miR-96-5p may be a potential therapeutic target for HCC.

MeSH terms

  • Apoptosis / drug effects
  • Apoptosis / radiation effects
  • Carcinoma, Hepatocellular / drug therapy
  • Carcinoma, Hepatocellular / genetics*
  • Carcinoma, Hepatocellular / pathology
  • Caspase 9 / genetics*
  • Cell Movement / drug effects
  • Cell Movement / genetics
  • Cell Proliferation / drug effects
  • Cell Proliferation / genetics
  • Doxorubicin / administration & dosage
  • Drug Resistance, Neoplasm / drug effects
  • Drug Resistance, Neoplasm / radiation effects
  • Gene Expression Regulation, Neoplastic / drug effects
  • Gene Expression Regulation, Neoplastic / radiation effects
  • Hep G2 Cells
  • Humans
  • Liver Neoplasms / genetics*
  • Liver Neoplasms / pathology
  • MicroRNAs / antagonists & inhibitors
  • MicroRNAs / genetics*
  • Transfection
  • Ultraviolet Rays

Substances

  • MIRN96 microRNA, human
  • MicroRNAs
  • Doxorubicin
  • Caspase 9