Expression of focal adhesion kinase in human lens epithelial cells induced by hydrogen peroxide

Abstract

Background The pathogenesis of age-related cataract is associated with the apoptosis of lens epithelial cells (LECs) caused by oxidative stress.Previous studies showed that intracellular focal adhesion kinase (FAK) pathway can be activated by H2O2 in vitro,which induced apoptosis of cells.To investigate the effect of oxidative on FAK expression in LECs is one of important studies in the prevention of age-related cataract.Objective This study was to investigate the expression and function of FAK in human LECs treated by H2O2.Methods Human LECs strain (HLECs-B3) were cultured in vitro in the low glucose DMEM with 10％ fetal bovine serum.Different concentrations (0,30,50,70,100,300,500,700,1000 μmol/L) of H2O2 were added into the culture medium for 24 hours.The survival rate of the cells was detected by Cell Counting Kit-8 (CCK-8) assay.Cell morphology as well as the expression and distribution of FAK in the cells were observed by immunofluorescent staining under the laser confocal microscope.Apoptosis was observed by hoechst33258 staining,and Western blot assay was used to quantitatively detect the expression and phosphorylation of FAK.Results The survival rate of the cells was (1.00±0.03) ％,(1.24±0.03)％,(1.36±0.24) ％,(0.93±0.02)％,(1.75±0.19)％,(1.37±0.18) ％,(0.64±0.01)％,(0.59±0.11)％,(0.14±0.05)％ in 0,30,50,70,100,300,500,700,1000 μmol/L H2O2 groups,with a significant difference among them (F =95.30,P =0.00).The survival rates of the cells in the below 300 μmol/L H2O2 groups were significantly higher than those in the 0 μmol/L H2O2 group,and survival rates of the cells in the above 500 μmol/L H2O2 groups were significantly lower than those in the 0 μmol/L H2O2 group(all at P＜0.05).After H2 O2 treatment for 24 hours,HLECs-B3 cells transformed from polygon shape to spindle shape and extended pseudopodiums,meanwhile the green fluorescence for FAK exhibited in the cytoplasm.Cell apoptosis was found in the 1000 μ mol/L H2O2 group.Western blot assay revealed that the expressing levels (grey scale) were significantly different among the various groups (F=28.08,P=0.00),and FAK expressing levels in the below 300 μmol/L H2O2 groups were significantly higher than those of the 0 μmol/L H2O2 group; while the expressing levels in the above 500 μmol/L H2O2 groups were lower than those of the control 0 μmol/L H202 group (all at P＜0.05).After treated by different concentrations of H2O2,the phosphorylation level of intracellular FAK (p-FAK) was significantly higher in 3 hours group than that in 30 minutes group (all at P＜0.05).Conclusions H2 O2 can affect the survival,proliferation and morphology of human LECs by activating the intracellular FAK pathway,indicating that FAK may play roles in the regulation process of cell biological behavior. Key words: Oxidative stress; Hydrogen peroxide; Lens epithelial cell; Focal adhesion kinase