茶多酚诱导鼻咽癌细胞cyclin D1表达下调

Tea Polyphenols Down- Regulated Expression of Cyclin D1 in Nasopharyngeal Carcinoma Cells

目的：探索茶多酚及其单体抑制鼻咽癌细胞增殖的分子机制。方法：应用光学显微镜、 MTT测定、流式细胞仪、报告基因和 Western blot分析等方法，研究茶多酚及其单体对细胞增殖和细胞周期的影响及分子机理。结果：茶多酚处理鼻咽癌细胞 CNE1- LMP1 24 h后，分裂相细胞显著减少，细胞增殖受到抑制，细胞的生存率从 100％下降到 38.1％ (200μ g/ml)； S期细胞明显减少，从 22.20％下降至 13.16％ (200μ g/ml)， G0/G1细胞所占百分率增加，从 68.50％上升至 74.08％，细胞出现 G1/S阻滞。同时， cyclin D1基因启动子转录活性显著下调，与对照组比下降 4～ 5倍，但相同浓度的茶多酚与 (－ )- epigallocatechin- 3- gallate(EGCG)处理没有显著性差别， cyclin D1蛋白表达水平明显降低。采用荧光酶双报告基因系统分析，发现茶多酚处理 12～ 14 h后， AP- 1、 NFκ B的反式激活活性均显著下降，与对照组 (0μ g/ml)比分别下降 5～ 6倍、 7～ 8倍，且呈明显的量效关系。结论：茶多酚能抑制鼻咽癌细胞 CNE- LMP1增殖，茶多酚诱导所致 cyclin D1基因的转录和表达下调可能在其中起着重要作用。

Objective： This stduy was designed to investigate the molecular mechanism of cell proliferation inhibited by tea polyphenols in nasopharyngeal carcinoma cell line CNE- LMP1. Method： Light microscope, MTT assay, flow cytometry, Western blot,and reporter gene analysis were applied to investigate the effects of tea polyphenols and(－ )- epigallocatechin- 3- gallate (EGCG) on the cell cycle and related molecular mechanisms. Result： After treatment of CNE- LMP1 cells with tea polyphenols(200μ g/ml), the number of proliferating cells was obviously decreased as determined by light microscopy, and the survival rate of cells decreased from 100％ to 38.1％ as determined by MTT assay. With the increase of tea polyphenols concentrations, the number of cells in S- phase was obviously decreased from 22.20％ to 13.16％ (200μ g/ml), and the number of cells in Phase G1 were elevated from 68.50％ to 74.08％ . It suggested that tea polyphenols could arrest the cell cycle at G1/S checkpoint. The transcription and the expression of cyclin D1 were obviously declined 4－ 5 fold. Furthermore, after treatment with tea polyphenols, transactivities of NFκ B and AP- 1 was obviously down- regulated in CNE- LMP1 cells for 5－ 6 and 7－ 8 fold, respectively. Conclusion： Tea polyphenols could arrest cell cycle and inhibit cells proliferation of nasopharyngeal carcinoma, and down- regulation of the gene transcription and expression of cyclin D1 might also be involved in these events.