Acute liver injury upregulates microRNA-491-5p in mice, and its overexpression sensitizes Hep G2 cells for tumour necrosis factor-alpha-induced apoptosis.

BACKGROUND MicroRNAs (miRNAs) have emerged as novel genetic regulators of cell functions such as proliferation, apoptosis and cancer. AIMS The aim of this study was to evaluate the role of a specific miRNA in modulating hepatic cell functions. METHODS C57Bl/6 mice were administered anti-fas receptor antibodies to induce liver cell apoptosis. miRNAs were purified from the liver tissue and evaluated using an miRNA microarray. The role of miRNA-491_5p, which was overexpressed in the model, in modulating hepatic cell functions was evaluated. miRNA-491_5p was overexpressed in Hep G2 cells, followed by the addition of tumour necrosis factor (TNF)-alpha, and induction of apoptosis as well as genes involved in apoptosis pathways were evaluated. The effect of miRNA-491_5p target genes on apoptosis was also analysed by inhibiting their expression by siRNA-induced gene silencing. RESULTS Upregulation of miRNA-491_5p was found in a high-dose anti-fas receptor antibody group. Overexpression of microRNA-491_5p sensitized Hep G2 cells for TNF-alpha-induced apoptosis, and also caused an inhibition of alpha-fetoprotein, (AFP), heat shock protein-90 (hsp-90) and nuclear factor-kappaB (NF-kappaB). Overexpression of miRNA-491_5p or inhibition of AFP and hsp-90 resulted in an increased apoptosis in TNF-alpha-treated Hep G2 cells. CONCLUSIONS One of the miRNAs that is associated with the acute liver injury mouse model, miRNA-491_5p, sensitizes Hep G2 cells for TNF-alpha-induced apoptosis, at least in part, by inhibiting AFP, hsp-90 and NF-kappaB.