Abstract
BACKGROUND Cataract is associated with increased apoptosis of the epithelial cells of the ocular lens. Previous studies have shown that microRNA-378a (miR-378a) has a role in the development of cataract, but the molecular mechanisms remain unclear. This study aimed to investigate the effects of miR-378a in human lens epithelial cells (HLECs) in vitro and normal lens tissues and cataract tissues. MATERIAL AND METHODS HLECs were grown in culture. Quantitative reverse transcription polymerase chain reaction (RT-qPCR) and Western blot were used to examine gene expression levels. The MTT and TUNEL assay measured cell growth and apoptosis. Changes in the fluorescence ratio of ethidium to dihydroethidium (E: DHE) and in 6-carboxy-2',7'-dichlorodihydrofluorescein diacetate (C-H₂DCFDA) were used to detect superoxide (O₂⁻) and hydrogen peroxide (H₂O₂). The expression levels of miR-378a and the superoxide dismutase 1 gene (SOD1) were measured in normal human lens tissues and cataract tissues. RESULTS Upregulation of miR-378a reduced the expression of SOD1. Levels of O₂⁻ were upregulated and H₂O₂ was slightly down-regulated by miR-378a. The use of a miR-378a mimic suppressed cell growth and enhanced apoptosis of HLECs, which were reversed by the use of a miR-378a inhibitor. SOD1 overexpression rescued the miR-378a-induced phenotypes of HLEC cells. Treatment with the PI3K inhibitor, LY294002, reversed miR-378a and ROS-regulated proliferation and apoptosis of HLEC cells. Also, miR-378a was upregulated, and SOD1 was down-regulated in human cataract tissues. CONCLUSIONS In HLECs, expression of miR-378a regulated ROS and PI3K/AKT signaling, and miR-378a was upregulated, and SOD1 was down-regulated in human cataract tissue.