Insulin-like growth factor-1 induces migration and expression of laminin-5 in cultured human corneal epithelial cells

PURPOSE. The effects of insulin-like growth factor (IGF)-1 on laminin (Ln)-5 and the associated integrins during in vitro HCEC migration were examined. Also investigated were the effects of IGF-1 on the migration of human corneal epithelial cells (HCECs). METHODS. HCEC migration was examined by wound-healing and chemoattraction assays. For migration inhibition assays, HCECs were pretreated with inhibitors of the IGF-1 receptor (αIR3), the PI3-K/AKT pathway (LY294002), and the MEK-ERK pathway (PD98059). The expression levels of Ln-5 and fibronectin (Fn) were determined by Western blot analysis, and the expression levels of the β1 and α3 integrins were determined by confocal microscopy and Western blot analysis. The migration inhibition with anti-integrin α3 and β1 antibodies was also determined. RESULTS. HCEC migration was significantly increased in the presence of IGF-1 and Ln-5. IGF-1 enhanced the production of Ln-5 in both a dose- and time-dependent manner, and this upregulation was blocked by pretreatment with αIR3 or LY294002. IGF-1 treatment upregulated expression of β1 integrin, but not α3 integrin. The HCEC migration facilitated by IGF-1 was inhibited with the anti-integrin antibody for β1. However, there was no cross-talk between Ln-5 and integrin β1 production. CONCLUSIONS. The results reveal that IGF-1 induces HCEC migration through the independent production of Ln-5 and β1 integrin, which are directed at least in part by activation of the PI3-K/AKT pathway, but are not affected by the MEK-ERK pathway.