Katiyar S K, Agarwal R, Mukhtar H
Department of Dermatology, University Hospitals of Cleveland, Case Western Reserve University, OH 44106.
Cancer Lett. 1993 Sep 30;73(2-3):167-72. doi: 10.1016/0304-3835(93)90260-g.
Our studies and others have shown the cancer chemopreventive effects of chronic administration of green tea in several animal tumor models. In this study, the administration of a polyphenolic fraction isolated from green tea (GTP) by oral intubation at a dose of 5 mg in 0.2 ml water 30 min prior to challenge with carcinogen, afforded significant protection against both diethylnitrosamine (DEN)- and benzo(a)pyrene (BP)-induced forestomach and lung tumorigenesis in A/J mice. The protective effects were evident by a decrease in numbers of tumors/mouse in GTP-fed groups compared to non GTP-fed controls. In the forestomach tumorigenesis protocol, GTP afforded 71 and 66% protection against, respectively DEN- and BP-induced tumor multiplicity. In the case of lung tumorigenesis protocol, however, the protective effects of GTP were 41 and 39%, respectively. Histological examination of forestomach tumors showed significantly lesser number of squamous cell carcinoma formation in GTP-fed groups of mice compared to carcinogen alone-treated controls. When pulmonary tumors were examined histologically, no adenocarcinomas were observed in GTP-fed groups compared to 15% mice with adenocarcinomas in DEN and BP alone-treated controls. The results of this study suggest that limited doses of GTP administration by gavage 30 min prior to carcinogen challenge may afford protection against carcinogen-induced tumorigenesis in internal body organs.
我们的研究以及其他研究表明，在多种动物肿瘤模型中，长期给予绿茶具有癌症化学预防作用。在本研究中，于用致癌物攻击前30分钟，通过口服插管以5毫克剂量在0.2毫升水中给予从绿茶中分离出的多酚组分（GTP），对A/J小鼠的二乙基亚硝胺（DEN）和苯并(a)芘（BP）诱导的前胃和肺肿瘤发生均提供了显著保护。与未喂食GTP的对照组相比，喂食GTP组的每只小鼠肿瘤数量减少，这表明了保护作用。在前胃肿瘤发生实验方案中，GTP分别对DEN和BP诱导的肿瘤多发性提供了71%和66%的保护。然而，在肺肿瘤发生实验方案中，GTP的保护作用分别为41%和39%。对前胃肿瘤的组织学检查显示，与仅用致癌物处理的对照组相比，喂食GTP的小鼠组中鳞状细胞癌形成的数量显著减少。当对肺部肿瘤进行组织学检查时，喂食GTP的组中未观察到腺癌，而在仅用DEN和BP处理的对照组中，有15%的小鼠出现腺癌。本研究结果表明，在致癌物攻击前30分钟通过灌胃给予有限剂量的GTP可能对致癌物诱导的体内器官肿瘤发生提供保护。
