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采用腹腔注射二乙基亚硝胺( D E N)启动、并用 C Cl4 加于三分之二肝切除促进形成的大鼠肝癌癌前病变模型,以研究茶多酚、茶色素对肝癌癌前病变的抑制作用。试验组分别饮用含01% 茶多酚或01% 茶色素的水,用谷胱甘肽硫转移酶( G S T) Pi阳性灶的密度和面积作为判断肝癌癌前病变发生和进展程度的指标,同时用免疫印迹法测定肝脏组织 G S T Pi蛋白水平,并用 Northern Blot方法检测 G S T Pim R N A 的转录活性。结果显示:茶多酚和茶色素组对 G S T Pi阳性灶的面积抑制率分别为72% 和60% ,对阳性灶数目的抑制率分别为44% 和50% 。用 G S T Pi多克隆抗体进行的免疫印迹分析显示:肝癌癌前病变模型中 G S T Pi蛋白表达明显升高,茶多酚和茶色素有不同程度的抑制作用。 G S T Pim R N A 的改变基本与 G S T Pi蛋白的变化相一致。试验表明:茶叶中抗氧化成分茶多酚和茶色素能够在不同水平上拮抗 G S T Pi的过度表达,这可能是茶多酚、茶色素抑制肿瘤发生和发展的机制之一。
Intraperitoneal injection of diethylnitrosamine (D E N) was initiated and CCl 4 was added to a two-thirds hepatectomy to promote the formation of rat precancerous lesion models of liver cancer to study the effects of tea polyphenols and tea pigments on precancerous liver cancer. Inhibition of the lesion. The experimental group drank water containing 01% tea polyphenols or 01% tea pigments respectively. The density and area of glutathione-S-transferase (GST)-P1 positive lesions were used as the precancerous lesions of hepatocellular carcinoma. And the degree of progress indicators, while the liver tissue G S T Pi protein level was measured by Western blotting, and the Northern blot assay was used to detect the transcription activity of G S T Pim R N A . The results showed that the area-specific inhibitory rates of G-sTP-positive lesions in the tea polyphenols and tea pigments group were 72% and 60%, respectively, and the inhibition rates for the number of positive lesions were 44% and 50%, respectively. The immunoblotting analysis with GST-PI polyclonal antibody showed that the expression of GSTp-Pi protein in the precancerous lesion model of liver cancer was significantly increased, and the tea polyphenols and tea pigments had different degrees of inhibition. The change of GST-PimRNA is basically consistent with the change of GSTp-Pi protein. Experiments showed that tea antioxidants such as tea polyphenols and tea pigments can antagonize the over-expression of GST-Pi at different levels. This may be one of the mechanisms by which tea polyphenols and tea pigments inhibit tumorigenesis and development.