Inhibitory effect of microRNA-34a on retinal pigment epithelial cell proliferation and migration.

Purpose: Retinal pigment epithelial (RPE) cells play important roles in ophthalmologic diseases such as proliferative vitreoretinopathy, AMD, and diabetic retinopathy. MicroRNA-34a (miR-34a) has been reported to be important in the regulation of cell proliferation, migration, differentiation, and apoptosis. In this study, we explored the effects of miR-34a on RPE cells.

Methods: The expression level of miR-34a in subconfluent and postconfluent ARPE-19 cells was investigated with quantitative real-time PCR. MicroRNA mimic and small interfering RNA (siRNA) were transiently transfected into RPE cells. Transfected RPE cells were analyzed with WST-1 proliferation assay, and their migration was analyzed with transwell assay and in vitro scratch study. The expression or activation of target proteins was detected by Western blotting.

Results: MicroRNA-34a was significantly downregulated in subconfluent ARPE-19 cells compared with postconfluent cells. Introduction of miR-34a inhibited the proliferation and migratory ability of RPE cells without obvious cell apoptosis. In miR-34a transfected cells, many important proliferation and/or migration related molecules such as c-Met, CDK2, CDK4, CDK6, E2F1, and phosphorylated-Cdc2 (p-Cdc2) were downregulated. Small interfering RNA designed to target c-Met also inhibited the proliferation and migration of RPE cells and downregulated CDK2, CDK6, E2F1, and p-Cdc2.

Conclusions: MicroRNA-34a is downregulated in subconfluent RPE cells. MicroRNA-34a can inhibit the proliferation and migration of RPE cells through downregulation of its targets c-Met and other cell cycle-related molecules. Our results indicated that miR-34a is involved in the regulation of RPE cells.