Inhibition of adenoma progression to adenocarcinoma in a 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone-induced lung tumorigenesis model in A/J mice by tea polyphenols and caffeine

• Published in: Cancer research (Chicago, Ill.) Ill.), 2006-12, Vol.66 (23), p.11494-11501
• Main Authors: Lu, Gang, Liao, Jie, Yang, Guangyu, Reuhl, Kenneth R, Hao, Xingpei, Yang, Chung S
• Format: Article
• Language: English
• Subjects: Adenocarcinoma - metabolism; Adenocarcinoma - pathology; Adenocarcinoma - prevention & control; Adenoma - chemically induced; Adenoma - pathology; Adenoma - prevention & control; Analysis of Variance; Animals; Caffeine - administration & dosage; Caffeine - therapeutic use; Catechin - administration & dosage; Catechin - analogs & derivatives; Catechin - therapeutic use; Cell Proliferation - drug effects; Disease Progression; Female; Flavonoids - administration & dosage; Flavonoids - therapeutic use; Immunohistochemistry; JNK Mitogen-Activated Protein Kinases - metabolism; Lung - drug effects; Lung - metabolism; Lung - pathology; Lung Neoplasms - chemically induced; Lung Neoplasms - pathology; Lung Neoplasms - prevention & control; Mice; Mice, Inbred Strains; Mitogen-Activated Protein Kinase 1 - metabolism; Mitogen-Activated Protein Kinase 3 - metabolism; Nitrosamines - administration & dosage; Nitrosamines - toxicity; Phenols - administration & dosage; Phenols - therapeutic use; Phosphorylation - drug effects; Polyphenols; Proliferating Cell Nuclear Antigen - analysis; Tea - chemistry; Time Factors
• ISSN: 0008-5472; 1538-7445
• DOI: 10.1158/0008-5472.can-06-1497

The present study investigated the inhibitory effects of Polyphenon E [a standardized green tea polyphenol preparation containing 65% (-)-epigallocatechin-3-gallate] and caffeine on 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced lung tumor progression from adenoma to adenocarcinoma. Female A/J mice were treated with a single dose of NNK (103 mg/kg body weight, i.p.) and kept for 20 weeks for the mice to develop lung adenomas. The mice were then given a solution of 0.5% Polyphenon E or 0.044% caffeine as the sole source of drinking fluid until week 52. Both treatments significantly decreased the number of visible lung tumors. Histopathologic analysis indicated that Polyphenon E administration significantly reduced the incidence (by 52%) and multiplicity (by 63%) of lung adenocarcinoma. Caffeine also showed marginal inhibitory effects in incidence and multiplicity of adenocarcinoma (by 48% and 49%, respectively). Markers of cell proliferation, apoptosis, and related cell signaling were studied by immunohistochemistry, and the labeling index and staining intensity were quantified by the Image-Pro system. Polyphenon E and caffeine treatment inhibited cell proliferation (by 57% and 50%, respectively) in adenocarcinomas, enhanced apoptosis in adenocarcinomas (by 2.6- and 4-fold, respectively) and adenomas (both by 2.5-fold), and lowered levels of c-Jun and extracellular signal-regulated kinase (Erk) 1/2 phosphorylation. In the normal lung tissues, neither agent had a significant effect on cell proliferation or apoptosis. The results show that tea polyphenols (and perhaps caffeine) inhibit the progression of NNK-induced lung adenoma to adenocarcinoma. This effect is closely associated with decreased cell proliferation, enhanced apoptosis, and lowered levels of c-Jun and Erk1/2 phosphorylation.