TGF-β2 induces epithelial-mesenchymal transition in cultured human lens epithelial cells through activation of the PI3K/Akt/mTOR signaling pathway

The present study aimed to investigate whether the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) signaling pathway is involved in the transforming growth factor β2 (TGF-β2)-induced epithelial-mesenchymal transition (EMT) in human lens epithelial (HLE) cells. HLEB-3 cells were cultured and stimulated with 10 ng/ml TGF-β2 for 24 h. Western blotting was then performed to analyze the expression levels of connexin 43 and fibronectin, and the activities of Akt and mTOR. Confocal cell immunofluorescence was used to observe the expression of phosphorylated (p)-Akt. The toxicity of 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (LY294002) was assessed using a Cell Counting Kit-8 assay, and inhibition investigations were performed using a PI3K inhibitor. The expression of connexin 43 was suppressed and the expression of fibronectin was increased when the cells were stimulated with 10 ng/ml TGF-β2 for 24 h. In addition, Akt and mTOR were activated during TGF-β2-induced EMT. Treatment of with LY294002 (20 µM) inhibited the activation of Akt and mTOR and effectively prevented TGF-β2-induced EMT in the HLECs. Therefore, the results of the present study indicated that TGF-β2 induces EMT by activating the PI3K/Akt/mTOR signaling pathway in cultured HLECs.