title: Irradiance-dependent UVB Photocarcinogenesis.
abstract: Ultraviolet B (UVB) radiation from the sun may lead to photocarcinogenesis of the skin. Sunscreens were used to protect the skin by reducing UVB irradiance, but sunscreen use did not reduce sunburn episodes. It was shown that UVB-induced erythema depends on surface exposure but not irradiance of UVB. We previously showed that irradiance plays a critical role in UVB-induced cell differentiation. This study investigated the impact of irradiance on UVB-induced photocarcinogenesis. For hairless mice receiving equivalent exposure of UVB radiation, the low irradiance (LI) UVB treated mice showed more rapid tumor development, larger tumor burden, and more keratinocytes harboring mutant p53 in the epidermis as compared to their high irradiance (HI) UVB treated counterpart. Mechanistically, using cell models, we demonstrated that LI UVB radiation allowed more keratinocytes harboring DNA damages to enter cell cycle via ERK-related signaling as compared to its HI UVB counterpart. These results indicated that at equivalent exposure, UVB radiation at LI has higher photocarcinogenic potential as compared to its HI counterpart. Since erythema is the observed sunburn at moderate doses and use of sunscreen was not found to associate with reduced sunburn episodes, the biological significance of sunburn with or without sunscreen use warrants further investigation.
authors.affiliation: Department of Dermatology, Kaohsiung Medical University Hospital, Department of Dermatology, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.|Department of Dermatology, Kaohsiung Municipal Ta-Tung Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.|Lipid Science and Aging Research Center, Kaohsiung Medical University, Kaohsiung, Taiwan.|Center of Environmental Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Cheng-Che E
authors.initials: CE
authors.lastname: Lan
authors.affiliation: Lipid Science and Aging Research Center, Kaohsiung Medical University, Kaohsiung, Taiwan.|Center of Environmental Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.|Department of Medical Laboratory Science and Biotechnology, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Ching-Shuang
authors.initials: CS
authors.lastname: Wu
authors.affiliation: Department of Dermatology, Kaohsiung Medical University Hospital, Department of Dermatology, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Shu-Mei
authors.initials: SM
authors.lastname: Huang
authors.affiliation: Department of Dermatology, Kaohsiung Medical University Hospital, Department of Dermatology, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Chin-Han
authors.initials: CH
authors.lastname: Wu
authors.affiliation: Department of Dermatology, Kaohsiung Medical University Hospital, Department of Dermatology, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Hsiao-Chi
authors.initials: HC
authors.lastname: Lai
authors.affiliation: Department of Dermatology, Kaohsiung Medical University Hospital, Department of Dermatology, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Yu-Ting
authors.initials: YT
authors.lastname: Peng
authors.affiliation: Department of Dermatology, Kaohsiung Medical University Hospital, Department of Dermatology, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.|Lipid Science and Aging Research Center, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Pao-Sheng
authors.initials: PS
authors.lastname: Hou
authors.affiliation: Department of Dermatology, Kaohsiung Medical University Hospital, Department of Dermatology, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Hui-Jun
authors.initials: HJ
authors.lastname: Yang
authors.affiliation: Department of Dermatology, Kaohsiung Medical University Hospital, Department of Dermatology, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Gwo-Shing
authors.initials: GS
authors.lastname: Chen
mesh_terms: D000328:Adult; D000818:Animals; D001973:Bromodeoxyuridine / Q000378:metabolism; D002070:Butadienes / Q000494:pharmacology; D063646:Carcinogenesis / Q000187:drug effects / Q000473:pathology / Q000528:radiation effects*; D002452:Cell Count; D002470:Cell Survival / Q000528:radiation effects; D002478:Cells, Cultured; D004249:DNA Damage; D003877:Dermatitis, Contact / Q000473:pathology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D016195:G2 Phase / Q000528:radiation effects; D006801:Humans; D007165:Immunosuppression Therapy; D015603:Keratinocytes / Q000187:drug effects / Q000473:pathology / Q000528:radiation effects; D008812:Mice, Hairless; D008938:Mitosis / Q000528:radiation effects; D009154:Mutation / Q000235:genetics; D009570:Nitriles / Q000494:pharmacology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011740:Pyrimidine Dimers / Q000378:metabolism; D012878:Skin Neoplasms / Q000473:pathology; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D014466:Ultraviolet Rays
chemical_list: D002070:Butadienes; D009570:Nitriles; D047428:Protein Kinase Inhibitors; D011740:Pyrimidine Dimers; D016159:Tumor Suppressor Protein p53; C113580:U 0126; D048049:Extracellular Signal-Regulated MAP Kinases; D001973:Bromodeoxyuridine