title: (-)-Epigallocatechin-3-gallate inhibition of ultraviolet B-induced AP-1 activity.
abstract: Green tea polyphenols have been shown to inhibit cancer in a variety of tumor models, including ultraviolet B (UVB)-induced non-melanoma skin cancer. In green tea extracts, the major dry mass constituent is the family of catechins, of which (-)-epigallocatechin-(3)-gallate (EGCG) is considered to be important for the chemopreventive activity. EGCG has been shown to have antioxidant properties, but there has been little progress toward identifying the specific targets and mechanisms of its action. Using cultured human keratinocytes, we show that UVB-induced AP-1 activity is inhibited by EGCG in a dose range of 5.45 nM to 54.5 microM. EGCG is effective at inhibiting AP-1 activity when applied before, after or both before and after UVB irradiation. EGCG also inhibits AP-1 activity in the epidermis of a transgenic mouse model. This work begins to define a mechanism by which EGCG could be acting to inhibit UVB-induced tumor formation.
authors.affiliation: Department of Radiation Oncology, University of Arizona Health Sciences Center, Tucson 85724, USA.
authors.forename: M
authors.initials: M
authors.lastname: Barthelman
authors.forename: W B
authors.initials: WB
authors.lastname: Bair
authors.forename: K K
authors.initials: KK
authors.lastname: Stickland
authors.forename: W
authors.initials: W
authors.lastname: Chen
authors.forename: B N
authors.initials: BN
authors.lastname: Timmermann
authors.forename: S
authors.initials: S
authors.lastname: Valcic
authors.forename: Z
authors.initials: Z
authors.lastname: Dong
authors.forename: G T
authors.initials: GT
authors.lastname: Bowden
mesh_terms: D000818:Animals; D016588:Anticarcinogenic Agents / Q000494:pharmacology*; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D002460:Cell Line; D006801:Humans; D015603:Keratinocytes / Q000378:metabolism / Q000528:radiation effects; D051379:Mice; D008822:Mice, Transgenic; D012680:Sensitivity and Specificity; D012878:Skin Neoplasms / Q000209:etiology / Q000517:prevention & control; D013662:Tea; D018808:Transcription Factor AP-1 / Q000037:antagonists & inhibitors* / Q000528:radiation effects*; D014466:Ultraviolet Rays
chemical_list: D016588:Anticarcinogenic Agents; D013662:Tea; D018808:Transcription Factor AP-1; D002392:Catechin; C045651:epigallocatechin gallate