Chan Ho Yee, Wang Huan, Tsang David S C, Chen Zhen-Yu, Leung Lai K
Department of Biochemistry, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong.
Nutr Cancer. 2003;46(1):93-100. doi: 10.1207/S15327914NC4601_12.
Polycyclic aromatic hydrocarbons (PAHs) are established cancer initiators that can be found in our food and environment. Some dietary plant polyphenols are strong inhibitors to PAH-induced mutagenesis, whereas others may not be as effective. To identify the chemopreventive compounds from a huge volume of dietary components, the development of an efficient screening method is required. In this study, a xenobiotic response element (XRE)-luciferase reporter plasmid was constructed to screen for some potential chemopreventive agents in tea against PAH-induced DNA damage. Tea is one of the most consumed beverages worldwide, and its beneficial effects on health have been documented. Previous studies have claimed that tea polyphenols could be protective against various cancers, and the rich database can be a source for comparison. Among the green and black tea polyphenols, the XRE-luciferase reporter assays suggested that only epigallocatechin gallate (EGCG) was effective in reducing XRE-driven luciferase assay in MCF-7 cells at the concentrations tested. Further study indicated EGCG could reduce CYP1A1 and CYP1B1 mRNA abundances and decrease the DMBA-DNA lesions. The results of DNA covalent binding of all tea polyphenols tested were consistent with the XRE-reporter assays. This study illustrated that the XRE-reporter assay was a viable screening test for dietary chemopreventive agents against PAH-initiated breast mutagenesis. It has the advantages of shorter sample processing time and producing no radioactive waste over directly measuring the CYP1A1/1B1 expressions, DNA lesion, or gel mobility shift assay.
多环芳烃（PAHs）是已确定的致癌起始剂，可在我们的食物和环境中找到。一些膳食植物多酚是PAH诱导诱变的强抑制剂，而其他一些可能效果不佳。为了从大量膳食成分中鉴定出化学预防化合物，需要开发一种高效的筛选方法。在本研究中，构建了一种外源物反应元件（XRE）-荧光素酶报告质粒，以筛选茶叶中一些潜在的针对PAH诱导的DNA损伤的化学预防剂。茶是全球消费最多的饮品之一，其对健康的有益作用已有文献记载。先前的研究声称茶多酚可以预防各种癌症，丰富的数据库可作为比较的来源。在绿茶和红茶多酚中，XRE-荧光素酶报告分析表明，在所测试的浓度下，只有表没食子儿茶素没食子酸酯（EGCG）能有效降低MCF-7细胞中XRE驱动的荧光素酶分析。进一步研究表明，EGCG可降低CYP1A1和CYP1B1 mRNA丰度，并减少DMBA-DNA损伤。所有测试的茶多酚的DNA共价结合结果与XRE报告分析一致。本研究表明，XRE报告分析是一种可行的针对PAH引发的乳腺诱变的膳食化学预防剂筛选试验。与直接测量CYP1A1/1B1表达、DNA损伤或凝胶迁移率变动分析相比，它具有样品处理时间短且不产生放射性废物的优点。
