Purpose: Transforming growth factor-beta 2 (TGF-beta2) is a potent growth inhibitor and apoptosis inducer. However, typically TGF-beta2 loses its growth-inhibitory and apoptosis-inducing effects but stimulates the migratory capacity of epithelial cells. In this study, we investigate the possible involvement of integrin and integrin-mediated signaling in TGF-beta2-promoted migration and adhesion in human lens epithelial cells.
Methods: A human lens epithelial cell line (HLE B-3) was treated with 100 pg/ml TGF-beta2 for 6 h, 12 h, and 24 h. In vitro wound healing assay and cell adhesion assay were performed to detect the effect of TGF-beta2 on HLEC adhesion and migration. Integrin beta1 expression changes in HLECs during the treatment of TGF-beta2 were detected in protein levels and mRNA levels using confocal microscopy, flow cytometric analysis, and real time quantitative reverse transcription polymerase chain reaction (RT-PCR). Focal adhesion kinase (FAK) activity was examined by FAK phosphorylation and total tyrosine phosphorylation during treatment with TGF-beta2 in HLEC. Production of endogenous TGF-beta2 was measured by ELISA assay.
Results: In this study, we found that TGF-beta2 significantly stimulated cell adhesion and migration in HLECs. By immunofluorescence staining and western blotting, we observed that TGF-beta2 markedly enhanced the expression of integrin beta1 and the Tyr-phosphorylation of focal adhesion kinase (FAK). Real time quantitative RT-PCR also showed the mRNA level of integrin beta1 was upregulated. Neutralizing anti-integrin beta1 monoclonal antibody significantly (p<0.05) inhibited TGF-beta2-promoted HLEC adhesion and migration.
Conclusions: TGF-beta2 promoted HLEC adhesion and migration in vitro. Integrin beta1 and integrin-mediated signaling are necessary for TGF-beta2-promoted adhesion and migration in human lens epithelial cells.