Cancer research
-
The pathogenesis of pulmonary tumors induced by a tobacco carcinogen, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), and its inhibition by black tea have been characterized. Female A/J mice (6 weeks old) were treated with a single dose of NNK (103 mg/kg of body weight, i.p.) on day 0, and the cell proliferation index was measured by the incorporation of bromodeoxyuridine (BrdUrd) immunohistochemically. The number of BrdUrd-labeled cells increased in the bronchiolar epithelium from day 2 to day 14, with the highest proliferation rate observed on day 5. ⋯ The cell proliferation rate in adenomas was also suppressed by black tea treatment. The present work demonstrates the antiproliferative activities of black tea and its polyphenols. Such activities, at the early and late stages of lung tumorigenesis, may be important for the cancer-chemopreventive activities of black tea.