Kuzuhara Takashi, Tanabe Akitoshi, Sei Yoshihisa, Yamaguchi Kentaro, Suganuma Masami, Fujiki Hirota
Laboratory of Biochemistry, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho, Tokushima, Japan.
Mol Carcinog. 2007 Aug;46(8):640-5. doi: 10.1002/mc.20332.
This article reviews two main topics: (1) the synergistic effects of multiple treatments with green tea catechin and (2) the direct binding of (-)-epigallocatechin gallate (EGCG) to both DNA and RNA molecules. Japanese drink green tea throughout the day, so we studied whether multiple treatments of cells with EGCG would enhance the expression of apoptosis-related genes, such as growth arrest and DNA damage-inducible gene (GADD153) and cyclin-dependent kinase inhibitor gene (p21(waf1)): The results suggest that the synergistic enhancement of both GADD153 and p21(waf1) gene expressions by multiple treatments plays a significant role in human cancer prevention with green tea beverage. Our previous observation-that nucleic acids extracted from catechin-treated cells are colored-allowed us to speculate that catechins directly interact with nucleic acids. Surface plasmon resonance assay (Biacore) indicated that four catechins, EGCG, (-)-epicatechin gallate (ECG), (+)-gallocatechin gallate (GCG), and (+)-catechin gallate (CG), bound to DNA oligomers. Cold spray ionization mass spectrometry (CSI-MS) analysis showed that one to three EGCG molecules bound to single-stranded 18 mers of DNA and RNA. Moreover, one or two molecules of EGCG bound to double-stranded AG:CT oligomers of various nucleotide lengths. Double-stranded DNA (dsDNA) oligomers were detected only as EGCG-bound forms at high temperature, whereas at low temperature both the free and bound forms were detected, suggesting that EGCG protects double-stranded DNA oligomers from double-stranded melting into single-stranded DNA. We assume that catechins accumulate in both double-stranded DNA and RNA molecules through multiple administrations of green tea beverage in in vivo, and that the accumulated green tea catechins play a significant role for human cancer prevention.
（1）绿茶儿茶素多种处理的协同效应，以及（2）（-）-表没食子儿茶素没食子酸酯（EGCG）与DNA和RNA分子的直接结合。日本人一整天都喝绿茶，因此我们研究了用EGCG对细胞进行多次处理是否会增强凋亡相关基因的表达，如生长停滞和DNA损伤诱导基因（GADD153）和细胞周期蛋白依赖性激酶抑制基因（p21（waf1））：结果表明，多次处理对GADD153和p21（waf1）基因表达的协同增强在绿茶饮品预防人类癌症中起重要作用。我们之前的观察——从儿茶素处理过的细胞中提取的核酸会显色——使我们推测儿茶素与核酸直接相互作用。表面等离子体共振分析（Biacore）表明，四种儿茶素，即EGCG、（-）-表儿茶素没食子酸酯（ECG）、（+）-没食子儿茶素没食子酸酯（GCG）和（+）-儿茶素没食子酸酯（CG），与DNA寡聚物结合。冷喷雾电离质谱（CSI-MS）分析表明，一到三个EGCG分子与单链18聚体的DNA和RNA结合。此外，一或两个EGCG分子与不同核苷酸长度的双链AG:CT寡聚物结合。双链DNA（dsDNA）寡聚物在高温下仅以EGCG结合形式被检测到，而在低温下自由形式和结合形式均被检测到，这表明EGCG可保护双链DNA寡聚物不发生双链熔解为单链DNA。我们推测，儿茶素通过体内多次饮用绿茶饮品而在双链DNA和RNA分子中积累，并且积累的绿茶儿茶素在预防人类癌症中起重要作用。
