(-)-epigallocatechin-3-gallate blocks the induction of nitric oxide synthase by down-regulating lipopolysaccharide-induced activity of transcription factor nuclear factor-kappa B
(-)-epigallocatechin-3-gallate blocks the induction of nitric oxide synthase by down-regulating lipopolysaccharide-induced activity of transcription factor nuclear factor-kappa B
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DOI：
10.1124/mol.52.3.465
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发表时间：
1997-09-01
影响因子：
3.6
通讯作者：
Lin, JK
中科院分区：
文献类型：
--
作者：
Lin, YL;Lin, JK
一氧化氮（NO）在炎症和多个阶段的癌症发生中起着重要作用。我们研究了各种茶多酚和咖啡因对巯基乙酸诱导和脂多糖（LPS）激活的腹腔巨噬细胞中NO合酶（NOS）诱导的影响。大蒜酸（GA）、（-）-表没食子儿茶素（EGC）和（-）-表没食子儿茶素-3-没食子酸酯（EGCG）（主要的茶儿茶素）被发现抑制活化的巨噬细胞中的诱导型一氧化氮合酶（iNOS）蛋白。EGCG是一种有效的抗肿瘤剂，具有抗炎和抗氧化特性，抑制NO的产生，通过释放到培养基中的亚硝酸盐的量来测量。EGCG和LPS共处理可抑制细胞NO的产生。用EGCG（5和10 μ M）处理6-24小时的脂多糖激活的巨噬细胞的可溶性提取物中的iNOS活性显著低于未经EGCG处理的巨噬细胞中的iNOS活性。Western印迹、逆转录-聚合酶链反应和北方印迹分析表明，与不含EGCG的巨噬细胞相比，含EGCG的脂多糖激活的巨噬细胞中iNOS的130-kDa蛋白和4.5-kb mRNA水平显著降低。电泳迁移率变动分析表明，EGCG阻断了核因子-κ B的激活，这是诱导iNOS所必需的转录因子。EGCG还阻断抑制剂kappa B从胞质组分中消失。这些结果表明，EGCG通过降低iNOS mRNA的表达来降低iNOS的活性和蛋白水平，并且这种降低可能通过阻止核因子-κ B与iNOS启动子的结合，从而抑制iNOS转录的诱导而发生。
Nitric oxide (NO) plays an important role in inflammation and multiple stages of carcinogenesis. We investigated the effect of various tea polyphenols and caffeine on the induction of NO synthase (NOS) in thioglycollate-elicited and lipopolysaccharide (LPS)-activated peritoneal macrophages. Garlic acid (GA), (-)-epigallocatechin (EGC), and (-)-epigallocatechin-3-gallate (EGCG), the major tea catechin, were found to inhibit inducible NOS (iNOS) protein in activated macrophages. EGCG, a potent antitumor agent with anti-inflammatory and antioxidant properties, inhibited NO generation, as measured by the amount of nitrite released into the culture medium. Inhibition of NO production was observed when cells were cotreated with EGCG and LPS. iNOS activity in soluble extracts of lipopolysaccharide-activated macrophages treated with EGCG (5 and 10 mu M) for 6-24 hr was significantly lower than that in macrophages without EGCG treatment. Western blot, reverse transcription-polymerase chain reaction, and Northern blot analyses demonstrated that significantly reduced 130-kDa protein and 4.5-kb mRNA levels of iNOS were expressed in lipopolysaccharide-activated macrophages with EGCG compared with those without EGCG. Electrophoretic mobility shift assay indicated that EGCG blocked the activation of nuclear factor-kappa B, a transcription factor necessary for iNOS induction. EGCG also blocked disappearance of inhibitor kappa B from cytosolic fraction. These results suggest that EGCG decreases the activity and protein levels of iNOS by reducing the expression of iNOS mRNA and the reduction could occur through prevention of the binding of nuclear factor-kappa B to the iNOS promoter, thereby inhibiting the induction of iNOS transcription.