title: Inhibition of both stage I and stage II skin tumor promotion in SENCAR mice by a polyphenolic fraction isolated from green tea: inhibition depends on the duration of polyphenol treatment.
abstract: The polyphenolic fraction isolated from green tea (GTP) is a potent inhibitor of phorbol ester 12-O-tetradecanoyl-phorbol-13-acetate (TPA)-induced tumor promotion in mouse skin. In this study, we assessed the effect of GTP on both stage I and stage II skin tumor promotion, and also analyzed the effect of duration of GTP treatment on skin tumor promotion in SENCAR mice. Topical application of GTP (6 mg/animal) concurrently with each application of either TPA (3.2 nmol) or mezerein (3.2 nmol) in stage I or stage II of the murine skin tumor promotion protocol, respectively, resulted in significant protection against skin papilloma formation in terms of both tumor multiplicity (42-50%) and tumor growth (43-54%). More profound and sustained protective effects of GTP were evident when it was applied continuously during both stage I and stage II of the skin tumor promotion protocol concurrently with TPA or mezerein treatments, respectively. Under this treatment regimen, compared to non-GTP-treated positive controls, GTP application showed 71%, 37% and 74% protection in terms of tumor multiplicity, tumor incidence and tumor growth, respectively. These data indicate that GTP inhibits both stage I and stage II of skin tumor promotion and that the inhibition of tumor promotion depends on the duration of GTP treatment.
authors.affiliation: Department of Dermatology, University Hospitals of Cleveland, Case Western Reserve University, OH 44106.
authors.forename: S K
authors.initials: SK
authors.lastname: Katiyar
authors.forename: R
authors.initials: R
authors.lastname: Agarwal
authors.forename: H
authors.initials: H
authors.lastname: Mukhtar
mesh_terms: D000818:Animals; D016588:Anticarcinogenic Agents / Q000494:pharmacology*; D002273:Carcinogens; D004224:Diterpenes; D005419:Flavonoids; D051379:Mice; D010636:Phenols / Q000494:pharmacology*; D010936:Plant Extracts / Q000494:pharmacology*; D011108:Polymers / Q000494:pharmacology*; D059808:Polyphenols; D012878:Skin Neoplasms / Q000139:chemically induced / Q000517:prevention & control*; D013662:Tea / Q000737:chemistry*; D013729:Terpenes; D013755:Tetradecanoylphorbol Acetate
chemical_list: D016588:Anticarcinogenic Agents; D002273:Carcinogens; D004224:Diterpenes; D005419:Flavonoids; D010636:Phenols; D010936:Plant Extracts; D011108:Polymers; D059808:Polyphenols; D013662:Tea; D013729:Terpenes; C011309:mezerein; D013755:Tetradecanoylphorbol Acetate