儿茶素抑制兔晶状体上皮细胞增殖

目的：探讨在绿茶提取物表没食子儿茶素没食子酸酯（EGCG）抑制兔晶状体上皮细胞增殖过程中， MEK/ERK1/2(mitogen-activated protein kinase kinase, MAPKK, MEK; extracellular signal-regulated kinase，ERK)及c-jun氨基末端激酶（c-Jun NH2-terminal protein kinase， JNK）信号转导通路的作用。 方法： 实验按EGCG浓度分50、100和200 μmol/L 3组。预先分别加入25、50 μmol/L的ERK活性拮抗剂PD980059孵育1 h；用噻唑蓝比色法（MTT比色法）测定晶状体上皮细胞增殖；用蛋白质免疫沉淀法(Western blotting)法检测ERK及JNK的磷酸化水平。 结果： （1）PD980059能明显增强EGCG抑制晶状体上皮细胞增殖的作用，呈浓度依赖性。（2）晶状体上皮细胞内磷酸化的ERK基础水平高。加入EGCG后其活性升高，随后逐渐回降,但始终高于基础水平；ERK的活化水平也随EGCG浓度的增加而增高。（3）细胞内JNK的54 kD亚型磷酸化的基础水平较低而46 kD亚型的较高；呈剂量与时间依赖性。 结论： EGCG可能部分通过调节ERK和JNK的磷酸化水平而抑制晶状体上皮细胞的增殖。

Inhibitory role of EGCG on proliferation of rabbit lens epithelial cells

AIM: (-)-Epigallocatechin - 3 - gallate (EGCG) is an extract from green tea, it could strongly inhibit the growth of cultured rabbit lens epithelial cells. This study explored the role of MEK1/ERK1/2 and JNK pathways in the proliferation inhibition of rabbit lens epithelial cells (LECs) induced by EGCG. METHODS: MTT colormetric assay was used to study the LECs growth inhibition. Western blotting were applied to study the kinsae phosphorylation level of ERK and JNK. RESULTS: (1) ERK activity blocker PD980059 could enhance EGCG - induced inhibition effect on proliferation of LECs compared with control groups in a dose - dependent manner. (2) Basic phosphorylation level of ERK was fairy high in LECs; and was increased by EGCG in a dose - dependent manner. The ERK phosphorylation reached its peak immediately after EGCG was added and stayed high even at the end of the test. (3) The basic phosphorylation - level of 54 kD JNK was weak but 46 kD was high in LECs; EGCG increased phosphorylated JNK level in a time and concentration - dependent manner in our test. CONCLUSION: It is suggested that the LEC proliferation inhibition induced by EGCG is, at least in part, through ERK and JNK pathways.