Essential Role of mTOR Signaling in Human Retinal Pigment Epithelial Cell Regeneration After Laser Photocoagulation

Abstract

This study assessed the role of mechanistic target of rapamycin (mTOR) pathway in the human adult retinal pigment epithelial (ARPE) cell response after laser photocoagulation (LP). The effect of mTOR inhibition on ARPE-19 cell was investigated by rapamycin treatment after LP. Cell viability and proliferation were explored using MTT and EdU assays, respectively. The expression of mTOR-related proteins and epithelial-mesenchymal transition (EMT) markers was verified by Western blot. Rapamycin retarded the LP area recovery in a dose-dependent manner by the 120h, while LP+DMSO vehicle-treated cells completely restored the lesion zone (P <= 0.01). ARPE-19 cell viability is significantly lower in LP + rapamycin 80 and 160 ng/ml treated cultures compared to LP control at 120 h (P <= 0.001). LP control group demonstrated significantly more proliferative cells compared to untreated cells at the 72 and 120h, whereas EdU-positive cell numbers in cultures treated with rapamycin at concentrations of 80 and 160 ng/ml were similar to baseline values (P <= 0.01). mTOR pathway activation is essential for regulation of the RPE cell migration and proliferation after LP. mTOR inhibition with rapamycin effectively blocks the migration and proliferation of the RPE cells. Our results demonstrate that mTOR has an important role in ARPE-19 cell as a regulator of cell behavior under stress conditions, suggesting that mTOR could be a promising therapeutic target for numerous retinal diseases.