title: Green tea phenol extracts reduce UVB-induced DNA damage in human cells via interleukin-12.
abstract: Green tea chemoprevention has been a focus of recent research, as a polyphenolic fraction from green tea (GTP) has been suggested to prevent UV radiation-induced skin cancer. Recently, it was demonstrated that GTP reduced the risk for skin cancer in a murine photocarcinogenesis model. This was accompanied by a reduction in UV-induced DNA damage. These effects appeared to be mediated via interleukin (IL)-12, which was previously shown to induce DNA repair. Therefore, we studied whether GTP induction of IL-12 and DNA repair could also be observed in human cells. KB cells and normal human keratinocytes were exposed to GTP 5 h before and after UVB. UVB-induced apoptosis was reduced in UVB-exposed cells treated with GTP. GTP induced the secretion of IL-12 in keratinocytes. The reduction in UV-induced cell death by GTP was almost completely reversed upon addition of an anti-IL-12-antibody, indicating that the reduction of UV-induced cell death by GTP is mediated via IL-12. The ability of IL-12 to reduce DNA damage and sunburn cells was confirmed in "human living skin equivalent" models. Hence the previously reported UV-protective effects of GTP appear to be mediated in human cells via IL-12, most likely through induction of DNA repair.
authors.affiliation: Department of Dermatology, University Kiel, Kiel, Germany.
authors.forename: Agatha
authors.initials: A
authors.lastname: Schwarz
authors.forename: Akira
authors.initials: A
authors.lastname: Maeda
authors.forename: David
authors.initials: D
authors.lastname: Gan
authors.forename: Tom
authors.initials: T
authors.lastname: Mammone
authors.forename: Mary S
authors.initials: MS
authors.lastname: Matsui
authors.forename: Thomas
authors.initials: T
authors.lastname: Schwarz
mesh_terms: D045744:Cell Line, Tumor; D004247:DNA / Q000528:radiation effects*; D004249:DNA Damage / Q000187:drug effects*; D006801:Humans; D018664:Interleukin-12 / Q000502:physiology*; D010636:Phenols / Q000494:pharmacology*; D013662:Tea / Q000737:chemistry*; D014466:Ultraviolet Rays
chemical_list: D010636:Phenols; D013662:Tea; D018664:Interleukin-12; D004247:DNA