TEA AND TEA POLYPHENOLS INHIBIT CELL HYPERPROLIFERATION, LUNG TUMORIGENESIS, AND TUMOR PROGRESSION

Both green and black tea have been shown to inhibit lung tumorigenesis in laboratory animal experiments. Green tea inhibited N-nitrosodiethy lamine-induced lung tumor incidence and multiplicity in female A/J mic e when tea was given either during the carcinogen treatment period or during the post-carcinogen treatment period. In a separate tumorigenes is model, both decaffeinated black tea and decaffeinated green tea inh ibited 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced lu ng tumor formation. Studies in which tea was administered during diffe rent time periods in relation to the NNK suggest that tea can inhibit lung tumorigenesis at both the initiation and promotion stages. The an tiproliferative effects of tea may be responsible for these anti-carci nogenic actions. Black tea polyphenol preparations decreased NNK-induc ed hyperproliferation. Black tea also inhibited the progression of pul monary adenomas to adenocarcinomas and the formation of spontaneous lu ng tumors in A/J mice. Growth inhibition by various tea polyphenols ha s been demonstrated in human lung H661 and H1299 cells. Although inhib ition of cell growth and signal transduction pathways by tea component s have been demonstrated the concentrations required to produce the ef fect are higher than achievable in tissues in vivo. More research is n ecessary to translate these laboratory results to applications in huma n chemoprevention.