自噬抑制剂3-MA对高糖诱导的人视网膜色素上皮细胞增生的抑制作用

背景糖尿病视网膜病变(DR)是糖尿病常见的并发症之一,视网膜色素上皮(RPE)细胞作为视网膜重要的组成细胞在DR的发生和发展中至关重要. 目的 探讨自噬抑制剂3-MA对高糖培养的人RPE细胞(hRPECs)增生的影响.方法 将体外培养的hRPECs分为对照组、高糖组和3-MA+高糖组,对照组细胞用含5 mmol/L葡萄糖的DMEM/F12培养基进行培养,高糖组采用含30 mmol/L葡萄糖的DMEM/F12培养基进行培养,干预组细胞先在DMEM/F12培养基中添加10 mmol/L的3-MA处理1h后,再添加30 mmol/L葡萄糖溶液进行培养.将培养的细胞以1×105/孔的密度接种于24孔细胞培养板中,待细胞80％融合后用含体积分数0.5％胎牛血清的培养基继续孵育24 h,使细胞周期同步化.倒置光学显微镜和透射电子显微镜下观察各组jRPECs的形态及超微结构;采用CCK-8法检测各组hRPECs的增生率;采用Western blot法检测各组hRPECs中自噬相关基因微管相关蛋白轻链3B(LC3B)蛋白的表达.结果 对照组细胞生长状态良好,细胞排列整齐;高糖组细胞体积稍增大,细胞数量明显多于对照组,而3-MA+高糖组细胞形态不规则,排列紊乱.透射电子显微镜下可见对照组细胞核呈圆形或卵圆形,亚细胞器形态均正常,未发现自噬小体;高糖组细胞中可见自噬溶酶体,而3-MA+高糖组可见自噬小体.对照组、高糖组、3-MA+高糖组细胞的增生率分别为(100.0±2.0)％、(116.9±5.2)%和(103.7±4.7)％,总体比较差异有统计学意义(F=13.526,P=0.006),高糖组的细胞增生率明显高于对照组和3-MA+高糖组,差异均有统计学意义(均P＜0.05),3-MA+高糖组与对照组间细胞增生率的差异无统计学意义(P＞0.05).与对照组比较,高糖组细胞中LC3B-Ⅰ蛋白表达减弱,LC3B-Ⅱ蛋白表达增强,而3-MA+高糖组细胞中LC3B-Ⅰ和LC3B-Ⅱ蛋白的表达强度与对照组接近.对照组、高糖组、3-MA+高糖组细胞中LC3B-Ⅱ/LC3B-Ⅰ值分别为0.131±0.065、2.504±0.097和0.274±0.007,组间总体比较差异有统计学意义(F=1 694.676,P=0.000),高糖组细胞中LC3B-Ⅱ/LC3B-Ⅰ值明显高于对照组和3-MA+高糖组,差异均有统计学意义(均P＜0.05),3-MA+高糖组与对照组间细胞中LC3B-Ⅱ/LC3B-Ⅰ值的差异无统计学意义(P＞0.05).结论 高糖可激活自噬过程并促进hRPECs增生,而自噬抑制剂3-MA在一定程度上抑制自噬进程,从而发挥抑制细胞增生的作用.

Inhibitory effects of autophagy inhibitor 3-MA on high glucose-induced proliferation of human retinal pigment epithelium cells

Background Diabetic retinopathy (DR) is one of the common complications of diabetes.Retinal pigment epithelium (RPE) cells,as important constituent cells of the retina,play important roles in the development and progression of DR.Objective This study was to investigate the suppressive effects of autophagy inhibitor 3-MA on the proliferation of human retinal pigment epithelium cells (hRPECs) following high glucose culture.Methods HRPECs were divided into control group,high-glucose group and 3-MA+high glucose group.The cells were cultured by the DMEM/F12 with 5 mmol/L glucose in the control group,and by the DMEM/F12 with 5 mmol/L glucose in the high glucose group and by the DMEM/F12 with 10 mmol/L 3-MA (for 1 hour firstly) and 30 mmol/L glucose in the 3-MA+high glucose group.The cells were inoculated into 24-well plate with the content of 1 ×105/well,and then the cells were consecutively cultured for 24 hours with DMEM/F12 containing 0.5％ fetal bovine serum after achieved attached 80％ confluence.The morphology and uhrastructure of the cells were examined by optics microscope and transmission electronic microscope.The proliferative rate of the cells was assayed by CCK-8 kit.The expression of autophagy-related gene microtubule associated protein light chain 3B (LC3B) in the cells was detected by Western blot and LC3B-Ⅱ/LC3B-Ⅰ value was quantitatively evaluated among the groups.Results The cells grew well with uniform size and regulatory arrangement in the control group.The cells in the high glucose group enlarged and the number of cells evidently increased.In the 3-MA+high glucose group,the cells decreased with a disorder arrangement.Under the transmission electron microscope,the cells were normal with the round-or oval-like nucleus and normal organelles in the control group,and autolysosome could be seen in the cells in the high glucose group.In the 3-MA+high glucose group,some autophagic bodies were found.The proliferative rate of the cells was (100.0±2.0) ％,(116.9-±5.2)％ and (103.7 ±4.7)％ in the control group,high glucose group and 3-MA+high glucose group respectively,showing a significant difference among the groups (F =13.526,P =0.006).The proliferative rate was considerably raised in the high glucose group compared with the control group and 3-MA+high glucose group (both at P＜0.05),but there was no significant difference in the proliferative rate of the cells between the control group and 3-MA+high glucose group (P＞0.05).Compared with the control group,the expressing intensity of LC3B-Ⅰ protein was weakened and that of LC3-Ⅱ protein was enhanced,and the expression intensity of LC3B-Ⅰ and LC3B-Ⅱ proteins in the 3-MA+high glucose group was similar to that in the control group.The LC3-Ⅱ/LC3-Ⅰ ratio was 0.131 ±0.065,2.504±0.097 and 0.274±0.007 in the control group,high glucose group and 3-MA+high glucose group,respectively,with significant differences among the groups (F =1 694.676,P =0.000),and the LC3-Ⅱ/LC3-Ⅰ ratio was increased in the high glucose group in comparison with the control group and the 3-MA+high glucose group (all at P＜0.05).No significant difference was found in the LC3B-Ⅱ/LC3B-Ⅰ ratio between the control group and 3-MA + high glucose group (P ＞ 0.05).Conclusions High glucose culture of hRPECs can activate autophagy process and promote cell proliferation.3-MA,an autophagy inhibitor,suppresses the high glucoseinduced growth of HRPECs by inhibiting autophagy process.