title: Ultraviolet-B-induced oxidative DNA base damage in primary normal human epidermal keratinocytes and inhibition by a hydroxyl radical scavenger.
abstract: To evaluate the effects of ultraviolet-induced environmental trauma on human skin cells, primary normal human epidermal keratinocytes were exposed to ultraviolet-B radiation (290-320 nm). We found that relatively low doses of ultraviolet-B (62.5-500 mJ per cm2) caused dose-dependent increases in 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG), a biomarker of oxidative DNA damage. Unirradiated normal human epidermal keratinocytes contained 1.49 (+/- 0.11) 8-oxo-dG per 10(6) 2'-deoxyguanosine (dG) residues in cellular DNA, which increased linearly to as high as 6.24 (+/- 0.85) 8-oxo-dG per 10(6) dG after irradiation with 500 mJ per cm2. Further, this oxidative damage was reduced by 60.7% when the cells were pretreated with 1 mM mannitol. As hydrogen peroxide (H2O2) is known to be generated during oxidative stress, its accumulation in ultraviolet-B-irradiated normal human epidermal keratinocytes was also assessed and correlated to 8-oxo-dG formation. An ultraviolet-B-induced increase in H2O2 was observed in normal human epidermal keratinocytes and its production was inhibited by the addition of catalase. Based on the ability of a neutral molecule like H2O2 to permeate membranes, our data indicate that, after ultraviolet-B irradiation, H2O2 migrates from the cytosol to the nucleus where it participates in a Fenton-like reaction that results in the production of hydroxyl radicals (OH*), which may then cause 8-oxo-dG formation in cellular DNA. This conclusion is supported by our data showing that OH* scavengers, such as mannitol, are effective inhibitors of oxidative DNA base damage. Although increased levels of 8-oxo-dG were previously found in immortalized mouse keratinocytes exposed to ultraviolet-B radiation, we now report the induction of 8-oxo-dG in normal human skin keratinocytes at ultraviolet-B doses relevant to human skin exposure.
authors.affiliation: Estee Lauder Research Laboratories, Melville, New York 11747, USA. epelle@estee.com
authors.forename: Edward
authors.initials: E
authors.lastname: Pelle
authors.forename: Xi
authors.initials: X
authors.lastname: Huang
authors.forename: Thomas
authors.initials: T
authors.lastname: Mammone
authors.forename: Kenneth
authors.initials: K
authors.lastname: Marenus
authors.forename: Daniel
authors.initials: D
authors.lastname: Maes
authors.forename: Krystyna
authors.initials: K
authors.lastname: Frenkel
mesh_terms: D000080242:8-Hydroxy-2'-Deoxyguanosine; D000970:Antineoplastic Agents / Q000494:pharmacology; D000975:Antioxidants / Q000494:pharmacology; D002478:Cells, Cultured; D004249:DNA Damage / Q000187:drug effects*; D003849:Deoxyguanosine / Q000031:analogs & derivatives* / Q000378:metabolism; D004234:Diuretics, Osmotic / Q000494:pharmacology; D000078404:Epidermal Cells; D004817:Epidermis / Q000378:metabolism / Q000528:radiation effects; D016166:Free Radical Scavengers / Q000494:pharmacology*; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D017665:Hydroxyl Radical / Q000378:metabolism; D015603:Keratinocytes / Q000166:cytology / Q000378:metabolism* / Q000528:radiation effects*; D008353:Mannitol / Q000494:pharmacology; D010084:Oxidation-Reduction; D012459:Salicylates / Q000494:pharmacology; D013890:Thiourea / Q000494:pharmacology; D014466:Ultraviolet Rays; D019207:beta Carotene / Q000494:pharmacology
chemical_list: D000970:Antineoplastic Agents; D000975:Antioxidants; D004234:Diuretics, Osmotic; D016166:Free Radical Scavengers; D012459:Salicylates; D019207:beta Carotene; C030865:copper bis(3,5-diisopropylsalicylate); D017665:Hydroxyl Radical; D008353:Mannitol; D000080242:8-Hydroxy-2'-Deoxyguanosine; D006861:Hydrogen Peroxide; D003849:Deoxyguanosine; D013890:Thiourea