title: Interplay Between Membrane Lipid Peroxidation and Photoproduct Formation in the Ultraviolet A-Induced Phototoxicity of Vemurafenib in Skin Keratinocytes.
abstract: According to some authors, the phototoxic response to ultraviolet A (UVA) of patients treated with vemurafenib (VB) may involve VB metabolites. However, the production of singlet oxygen and free radicals and photoproduct formation upon UVA light absorption by the lipophilic VB have been demonstrated. This work is aimed at determining the contribution of reactive oxygen species (ROS), lipid photoperoxidation, and VB photochemistry in the UVA-induced photocytotoxicity in NCTC 2544 keratinocytes. The potent membrane lipid peroxidation effectiveness of VB-photosensitization has been proved by the observation of an effective photohemolysis accompanied by thiobarbituric reactive substances (TBARS) formation in 2% red blood cell (RBC) suspensions. Photohemolysis is inhibited by human serum albumin (HSA) that binds VB and by the antioxidants 2,6-di-tert-butyl-4-methylphenol and Trolox. These data on RBC suggest that VB is readily incorporated in cell membranes and provide clues for understanding the UVA-induced VB-photosensitization of keratinocytes. In keratinocytes, ROS and TBARS formation with 10 µM VB is inhibited by approximately 40% and 50% by 30 µM Trolox and 50 µM vitamin E, respectively, but the light dose-dependent cell survival is unaffected. Whereas cell photokilling depends on the VB concentration, much smaller changes in the lethal doses (LD) than theoretically expected are observed for 25% or 50% cell photokilling when changing absorbed UVA doses and irradiation wavelengths. The lack of antioxidant effect on cell survival and the unexpectedly small LD dependence on absorbed UVA light doses and on irradiation wavelengths strongly suggest that, instead of metabolites, membrane photosensitization and photoproduct formation contribute to the cell photocytotoxicity.
authors: Hospital de Santa Maria, Faculdade de Medicina de Lisboa, Clínica Dermatologica Universitaria and Unidade de Investigação em Dermatologia, Instituto de Medicina Molecular, 1699 Lisboa Codex, Portugal.
authors: Ana
authors: A
authors: Teixeira
authors: INSERM, U1088, 80036 Amiens, France morliere.patrice@chu-amiens.fr.|CHU Amiens, Pôle Biologie, Pharmacie et Santé des Populations, Centre de Biologie Humaine, Laboratoire de Biochimie, D408, 80054 Amiens, France.|UFR de Pharmacie, Université de Picardie Jules Verne, 80036 Amiens, France.
authors: Patrice
authors: P
authors: Morlière
authors: Hospital de Santa Maria, Faculdade de Medicina de Lisboa, Clínica Dermatologica Universitaria and Unidade de Investigação em Dermatologia, Instituto de Medicina Molecular, 1699 Lisboa Codex, Portugal.
authors: João
authors: J
authors: Ferreira
authors: CHU Amiens, Pôle Biologie, Pharmacie et Santé des Populations, Centre de Biologie Humaine, Laboratoire de Biochimie, D408, 80054 Amiens, France.
authors: Marie-Alix
authors: MA
authors: Conte
authors: CHU Amiens, Pôle Biologie, Pharmacie et Santé des Populations, Centre de Biologie Humaine, Laboratoire de Biochimie, D408, 80054 Amiens, France.|UFR de Pharmacie, Université de Picardie Jules Verne, EA4666, 80036 Amiens, France.|UFR de Médecine, Université de Picardie Jules Verne, 80036 Amiens, France.
authors: Antoine
authors: A
authors: Galmiche
authors: INSERM, U1088, 80036 Amiens, France.|CHU Amiens, Pôle Biologie, Pharmacie et Santé des Populations, Centre de Biologie Humaine, Laboratoire de Biochimie, D408, 80054 Amiens, France.|UFR de Médecine, Université de Picardie Jules Verne, 80036 Amiens, France.
authors: Jean-Claude
authors: JC
authors: Mazière
authors: Département RDDM, Muséum National d'Histoire Naturelle, 75231 Paris, France.
authors: René
authors: R
authors: Santus
authors: Hospital de Santa Maria, Faculdade de Medicina de Lisboa, Clínica Dermatologica Universitaria and Unidade de Investigação em Dermatologia, Instituto de Medicina Molecular, 1699 Lisboa Codex, Portugal.
authors: Paulo
authors: P
authors: Filipe
mesh_terms: D000970:Antineoplastic Agents / Q000633:toxicity*; D000975:Antioxidants / Q000494:pharmacology; D002460:Cell Line; D017484:Dermatitis, Phototoxic / Q000209:etiology* / Q000378:metabolism / Q000473:pathology; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D004912:Erythrocytes / Q000187:drug effects* / Q000378:metabolism / Q000528:radiation effects; D006461:Hemolysis / Q000187:drug effects / Q000528:radiation effects; D006801:Humans; D007211:Indoles / Q000633:toxicity*; D015603:Keratinocytes / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects; D015227:Lipid Peroxidation / Q000187:drug effects*; D008563:Membrane Lipids / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects / Q000528:radiation effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D013449:Sulfonamides / Q000633:toxicity*; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism; D014466:Ultraviolet Rays / Q000009:adverse effects*; D000077484:Vemurafenib
chemical_list: D000970:Antineoplastic Agents; D000975:Antioxidants; D007211:Indoles; D008563:Membrane Lipids; D017382:Reactive Oxygen Species; D013449:Sulfonamides; D017392:Thiobarbituric Acid Reactive Substances; D000077484:Vemurafenib
keywords: UVA; keratinocytes.; photocytotoxicity; photoproduct; vemurafenib