Downregulation of microRNA-181a attenuates hydrogen peroxide-induced human lens epithelial cell apoptosis in vitro

The aim of the present study was to explore the effect of miRNA-181a on the ability of H2O2-induced apoptosis in human lens epithelial (HLE-B3) cells, which was closely linked with cataract. Lentivirus-based RNAi plasmid pLKO.1-puro-miR-181a was constructed. We transfected HLE-B3 cells with pLKO.1-puro-miR-181a lentivirus particles to down-regulate miR-181a expression. Cell apoptosis assay of HLE-B3 stable cell line with lenti-shR-miR-181a and the normal HLE-B3 cells in the presence of hydrogen peroxide (H2O2) was assessed by flow cytometry. Expression levels of two apoptosis-related genes [caspase-3 and BCL2 Associated X Protein (BAX)] and three potential target genes for miR-181a [c-MET Proto-Oncogene, Receptor Tyrosine Kinase (c-MET), cyclooxygenase 2(COX-2), Snail Family Zinc Finger 2(Slug)] were measured with real-time quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Malondialdehyde (MDA), superoxide dismutase (SOD), and catalase (CAT) levels were assessed by enzyme-linked immunosorbentassay (ELISA). Using qRT-PCR, we demonstrated that miR-181a was down-regulated in HLE-B3 cells after transfection of pLKO.1-puro-miR-181a lentivirus particles(P=0.0008). H2O2 induced a great loss of cell viability and down-regulation of miR-181a could partially compromise the cell viability following H2O2 treatment(P=0.0089). Moreover, the down-regulation of miR-181a significantly decreased H2O2-induced cell apoptosis. Additionally, down-regulation of miR-181a was also accompanied by suppression of caspase-3 and BAX, as well as down-regulation of COX-2 and MDA. Down-regulation of miR-181a can protect or rescue HLE-B3 cells in vitro from undergoing apoptosis after H2O2 exposure. The underlying molecular mechanisms of this protection may involve caspase-3 and BAX suppression, as well as COX-2 and MDA inhibition. Key words: Cataract; Lentivirus-based RNAi; Cell apoptosis; Human lens epithelial cells; miRNA-181a