title: Induction of unscheduled DNA synthesis in hairless mouse epidermis by ultraviolet light.
abstract: The activity of ultraviolet (UV) light to induce unscheduled DNA synthesis (UDS) was investigated in hairless mouse epidermis by means of an in vivo-in vitro assay using a liquid scintillation counting method. Groups of three to five 8-week-old female hairless mice were irradiated with UV-B or UV-A, then skin samples were taken and cultured individually in medium containing [3H]thymidine with or without hydroxyurea (HU) for 2 hr. DNA of the epidermis was extracted, and incorporation of [3H]thymidine and the DNA content were determined with a liquid scintillation counter and a fluorescence spectrophotometer, respectively. Induction of UDS was judged in terms of the UDS index [(the ratio of DNA synthesis in the presence of HU to that in its absence) x 100]. UV-B increased the UDS index 1 hr after irradiation of 500 J/m2, which corresponds to approximately 1 minimal erythema dose or 1 minimal edema dose, and showed a dose-dependent increase up to 17-fold in the UDS index at irradiation doses of 500 to 2,000 J/m2. In a time-course study, UV-B also increased replicative DNA synthesis (RDS) 48 hr after irradiation at 1,000 J/m2. On the other hand, UV-A did not increase the UDS index at irradiation doses of 2 x 10(5) to 8 x 10(5) J/m2. These results show that induction of UDS by UV irradiation depends on wavelength and an increase of RDS in the epidermis exposed to UV-B irradiation appears after induction of UDS.
authors.affiliation: Life Science Research Center, Shiseido Co., Ltd., Kanagawa, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Mori
authors.forename: H
authors.initials: H
authors.lastname: Kobayashi
authors.forename: M
authors.initials: M
authors.lastname: Naganuma
authors.forename: C
authors.initials: C
authors.lastname: Sugiyama
authors.forename: Y
authors.initials: Y
authors.lastname: Katsumura
authors.forename: C
authors.initials: C
authors.lastname: Furihata
mesh_terms: D000818:Animals; D004247:DNA / Q000096:biosynthesis / Q000187:drug effects / Q000528:radiation effects*; D004249:DNA Damage; D004307:Dose-Response Relationship, Radiation; D004487:Edema / Q000209:etiology; D004817:Epidermis / Q000187:drug effects / Q000528:radiation effects*; D004890:Erythema / Q000209:etiology; D005260:Female; D006918:Hydroxyurea / Q000494:pharmacology; D051379:Mice; D008812:Mice, Hairless; D013997:Time Factors; D014466:Ultraviolet Rays / Q000009:adverse effects*
chemical_list: D004247:DNA; D006918:Hydroxyurea