title: Inhibitory effects of silk protein, sericin on UVB-induced acute damage and tumor promotion by reducing oxidative stress in the skin of hairless mouse.
abstract: This study was conducted to assess protective effect of an antioxidant protein, sericin, on UVB-induced acute damage and tumor promotion in mouse skin. In experiment 1, HR-1 hairless mice were treated with 180 mJ/cm2 of ultraviolet B light (UVB) once daily for 1 and 7 days. The treatment for 7 days caused red sunburn lesions of the skin. The intensity of red color and area of these lesions were inhibited by the topical application of sericin at the dose of 5 mg after UVB treatment. Immunohistochemical analyses showed that the application of sericin significantly suppressed UVB-induced elevations in 4-hydroxynonenal (4-HNE), expression of cyclooxygenase-2 (COX-2) protein, and proliferating cell nuclear antigen (PCNA)-labeling index in the UVB-exposed epidermis. In experiment 2, HR-1 hairless mice were treated with 200 nmol of 7,12-dimethylbenz [alpha] anthracene (DMBA) followed 1 week later by irradiation with 180 mJ/ cm2 of UVB twice weekly for 22 weeks. The protective effect of sericin was evident in terms of significant reduction in tumor incidence and tumor multiplicity at the dose of 5 mg. The results suggest that sericin possesses photoprotective effect against UVB-induced acute damage and tumor promotion by reducing oxidative stress, COX-2 and cell proliferation in mouse skin.
authors.affiliation: Graduate School of Biosphere Science, Hiroshima University, Higashi-Hiroshima 739-8528, Japan.
authors.forename: Siqin
authors.initials: S
authors.lastname: Zhaorigetu
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Yanaka
authors.forename: Masahiro
authors.initials: M
authors.lastname: Sasaki
authors.forename: Hiromitsu
authors.initials: H
authors.lastname: Watanabe
authors.forename: Norihisa
authors.initials: N
authors.lastname: Kato
mesh_terms: D000818:Animals; D051379:Mice; D008812:Mice, Hairless; D018384:Oxidative Stress; D010456:Peptides, Cyclic / Q000502:physiology*; D047030:Sericins; D012878:Skin Neoplasms / Q000209:etiology / Q000517:prevention & control*; D014466:Ultraviolet Rays
chemical_list: D010456:Peptides, Cyclic; D047030:Sericins