Purpose:
Nerve growth factor (NGF) has been widely applied to clinical use in neurology yet recently came into use in ophthalmology. Several studies had validated that NGF promoted the healing of corneal wound. However, the molecular mechanism by which NGF functions in human cornea is required to discover. Herein, we investigated the possible effects of NGF on several major signaling pathways and cell growth in human corneal epithelial cells (HCECs).
Methods:
We examined the effect of NGF on cell cycle and proliferation in HCECs by flow cytometry and cell proliferation assay, respectively. The levels of D-type cyclins in NGF-treated HCECs were determined by Western blot. The TrkA, PI3K and MAPK pathways were then checked in cells stimulated with NGF for different time periods or cells undergoing a dose-dependent treatment. Furthermore, HCECs were treated with pathway inhibitors, LY294002 or PD98059, to confirm NGF-induced activations.
Results:
By analyzing cell proliferation and cell cycle under NGF treatment, we found that NGF had positive effect on the growth of HCECs, as well as D-type cyclins,and was correlated with the percentage of the G1 phase population. We also observed the time-dependent and dose-dependent effect of NGF on PI3K and MAPK pathways. Furthermore, NGF was confirmed to affect cell cycle progression of HCECs by regulating cyclin D through Akt and Erk activation upon the treatment with pathway inhibitors, LY294002 for Akt or PD98059 for Erk pathways.
Conclusions:
NGF stimulation favored cell proliferation and cell cycle progression of human corneal epithelial cells by activation of cyclin D via Akt and Erk signaling pathways, and might be a potential therapeutic factor in human corneal wound healing.
Keywords: cornea: basic science • cornea: epithelium • growth factors/growth factor receptors