title: Importance of UVA photoprotection as shown by genotoxic related endpoints: DNA damage and p53 status.
abstract: In order to demonstrate the importance of photoprotection in the UVA range (320-400 nm), an in vitro approach where sun formulations are spread on a quartz slide, and placed over human keratinocytes in culture is proposed as a convenient test for photoprotection assessment at the DNA level. Using the comet assay, DNA strand breaks, oxidative DNA damage or drug-induced DNA breaks were assessed. Accumulation of p53 protein was also studied as a marker for UV-induced genotoxic stress. Such a method was used to compare two formulations with different photostability. Spectroradiometry showed that a photounstable formulation lost its effectiveness in UVA screening when pre-irradiated by simulated sunlight (UVB+UVA). As a consequence, it was also shown that this formulation was not as protective as the photostable one at the genomic level. These data demonstrate that the loss of absorbing efficiency within UVA wavelengths due to photounstability may have detrimental consequences leading to impairments implicated in genotoxic events.
authors.affiliation: L'Oreal Research, Life Sciences Research, Phototoxicology Unit, Genotoxicity Group 1, av. E. Schueller, 93600 Aulnay-Sous-Bois, France. Imarrot@rd.loreal.com
authors.forename: Laurent
authors.initials: L
authors.lastname: Marrot
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Belaïdi
authors.forename: Jean-Roch
authors.initials: JR
authors.lastname: Meunier
mesh_terms: D002478:Cells, Cultured; D020552:Comet Assay; D004249:DNA Damage; D006801:Humans; D009153:Mutagens / Q000633:toxicity*; D013473:Sunscreening Agents; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D014466:Ultraviolet Rays
chemical_list: D009153:Mutagens; D013473:Sunscreening Agents; D016159:Tumor Suppressor Protein p53