Hydroxycamptothecin-induced apoptosis of human Tenon capsule fibroblast and its mechanism / 中华实验眼科杂志

ABSTRACT

Background The hyperplasia of human Tenon capsule fibroblasts (HTFs) is a common cause of filtering surgery failure in glaucomous eye.Researches demonstrated that hydroxycamptothecin is a cell cycle arresting drug and induce apoptosis of cancer and fibroblasts.However,its mechanism is currently less understood.Objective This study was to investigate whether hydroxycamptothecin induce the apoptosis of HTFs and explore the possible mechanism.Methods Human Tenon capsule tissue was obtained from EyeBank of Jiangsu Province Hospital.HTFs were cultured using explant method in vivo and passaged in DMEM containing 10％ FBS.The cells were identified using vimentin and keratin by immunochemistry,and the cells of generation 3-6 in the logarithmic growth phase were used in the experiment.The cells were incubated with 0.01,0.05 or 0.10 g/L hydroxycamptothecin for 5 minutes respectively,and the cells without any hydroxycamptothecin were served as the control group.Cell viability then was assessed by cell counting kit-8 (CCK8) for the optimal inhibition concentration.The cells were treated by 0.10 g/L hydroxycamptothecin for 24 hours,and the apoptotic rate of the cells were assayed with annexin V/PI double-staining.Mitochondrial membrane potential of HTFs was assessed using JC-1 staining.The expressions of caspase-3,caspase-9 and cytochrome C (cyt C) in mitochondria and cytoplasm of HTFs were detected by Western blot.Results The proliferative value (A450) of the HTFs 0,0.01,0.05,0.10 g/L was 0.9716±0.0608,0.8035 ± 0.0346,0.7048 ±0.0446,0.6265 ±0.0286,with a significant difference (F =26.372,P =0.002).A450 of HTFs in the 0.01,0.05,0.10 g/L groups was significantly lower than the control group (P＜0.05),with the lowest A450 value in the 0.10 g/L group.The apoptotic percentage of HTFs was (18.72±1.41)％,in the 0.10 g/L hydroxycamptothecin group and that of the control group was (3.67 ±0.36)％,showing a significant difference between them (t =-10.374,P=0.001).The expression intensity of caspase-3 and caspase-9 protein in HTFs was higher in the 0.10 g/L hydroxycamptothecin group than that in the control group.JC-1 staining showed that the green fluorescence of the monomer JC-1 in cytoplasm was stronger in the 0.10 g/L hydroxycamptothecin group than that in the control group,but the red fluorescence of the polymer JC-1 in the 0.10 g/L hydroxycamptothecin group was weaker than that in the control group.The grey scale of cyt C protein in HTFs in mitochondrion was 0.0605±0.0022 in the 0.10 g/L hydroxycamptothecin group,showing a significant increase in comparison with 0.0301 ±0.0016 of the control group (t=4.865,P=0.014).However,the grey scale of cyt C protein in cytoplasm was declined in the 0.10 g/L hydroxycamptothecin group than that in the control group (0.0605 ±0.0022 vs.0.0301 ±0.0016) (t =-11.177,P =0.001).Conclusions Hydroxycamptothecin can induce the apoptosis of HTFs through activating the mitochondrial apoptosis pathway.