Inhibition of ultraviolet B-mediated activation of nuclear factor κB in normal human epidermal keratinocytes by green tea Constituent (-)-epigallocatechin-3-gallate
Inhibition of ultraviolet B-mediated activation of nuclear factor κB in normal human epidermal keratinocytes by green tea Constituent (-)-epigallocatechin-3-gallate
复制标题
DOI：
10.1038/sj.onc.1206206
复制
发表时间：
2003-02-20
期刊：
影响因子：
8
通讯作者：
Mukhtar, H
中科院分区：
文献类型：
--
作者：
Afaq, F;Adhami, VM;Mukhtar, H
表没食子儿茶素没食子酸酯（Epigallocatechin-3-gallate，EGCG）是绿色茶的主要成分，具有显著的抗炎和癌症化学预防特性。研究已经显示了绿色茶和EGCG在细胞培养、动物模型和人类皮肤中的光化学预防作用。表没食子儿茶素没食子酸酯（EGCG）光化学预防作用的分子机制还不完全清楚。我们最近发现，正常人表皮角质形成细胞（NHEK）的EGCG治疗抑制紫外线（UV）B介导的有丝分裂原活化蛋白激酶（MAPK）途径的激活。在这项研究中，我们评估了EGCG对UVB介导的核因子κ B（NF-κ B）通路的调节作用，该通路在多种生理功能中起着关键作用，并参与炎症和癌症的发展。免疫印迹分析表明，用EGCG（10-40 μ m）处理NHEK 24小时，以剂量依赖的方式显著抑制UVB（40 mJ/cm（2））介导的I κ B α降解和磷酸化以及I κ K α激活。在时间依赖性方案中（UVB暴露后15和30分钟，1、2、3、6、12小时）也观察到UVB介导的IkappaB α降解和磷酸化以及IKK α激活。采用免疫印迹分析，酶联免疫吸附试验和凝胶迁移试验，我们证明，EGCG治疗的细胞导致了显着的剂量和时间依赖性抑制UVB介导的激活和核转位的NF-κ B/p65。本研究结果提示，EGCG通过调节NF-κ B通路发挥抗紫外辐射的作用，为EGCG的光化学防护作用提供了分子基础。
Epigallocatechin-3-gallate (EGCG), the major constituent of green tea, possesses significant anti-inflammatory and cancer chemopreventive properties. Studies have shown the photochemopreventive effects of green tea and EGCG in cell culture, animal models, and human skin. The molecular mechanism(s) of photochemopreventive effects of EGCG are incompletely understood. We recently showed that EGCG treatment of the normal human epidermal keratinocytes (NHEK) inhibits ultraviolet (UV)B-mediated activation of the mitogen-activated protein kinase (MAPK) pathway. In this study, we evaluated the effect of EGCG on UVB-mediated modulation of the nuclear factor kappa B (NF-kappaB) pathway, which is known to play a critical role in a variety of physiological functions and is involved in inflammation and development of cancer. Immunoblot analysis demonstrated that the treatment of NHEK with EGCG (10-40 mum) for 24 h resulted in a significant inhibition of UVB (40mJ/cm(2))-mediated degradation and phosphorylation of IkappaBalpha and activation of IKKalpha, in a dose-dependent manner. UVB-mediated degradation and phosphorylation of IkappaBalpha and activation of IKKalpha was also observed in a time-dependent protocol (15 and 30min, 1, 2, 3, 6, 12h post-UVB exposure). Employing immunoblot analysis, enzyme-linked immunosorbent assay, and gel shift assay, we demonstrate that EGCG treatment of the cells resulted in a significant dose- and time-dependent inhibition of UVB-mediated activation and nuclear translocation of a NF-kappaB/p65. Our data suggest that EGCG protects against the adverse effects of UV radiation via modulations in NF-kappaB pathway, and provide a molecular basis for the photochemopreventive effect of EGCG.