Effects of gypenosides on the expressions of p53 and p21 protein in photodamaged BALB/c mouse skin

Abstract

Objective To explore the mechanism underlying the effects of gypenosides (GP) against photodamage. Methods Eighty BALB/c mice were equally divided into 8 groups, i.e., blank control group (untreated), UVB model group (irradiated with UVB), GP I group (irradiated with UVB before topical application of GP), GPⅡ group (irradiated with UVB followed by topical application of GP), VitE I group (irradiated with UVB after topical application of Vitamine E cream), VitE Ⅱ group (irradiated with UVB followed by topical application of Vitamine E cream), Vehicle group Ⅰ (irradiated with UVB after application of the drug vehicle),and Vehicle group Ⅱ (irradiated with UVB before application of the drug vehicle). UVB irradiation was performed once every other day for 14 days. Mice were sacrificed after the last irradiation and skin specimens were obtained from the irradiated sites, and the levels of p53 and p21 protein were measured by Western blot in the specimens. Results The expression level of p53 protein was significantly lower in the blank control group than in the UVB model group (0.11 ± 0.08 vs. 0.22 ± 0.12) and GP Ⅰ group (0.44 ± 0.23, P < 0.01),in the blank control group and UVB model group than in the GP Ⅱ group (0.48 ± 0.24, P < 0.01, 0.05). VitE Ⅰ group (0.49 ± 0.29) and VitE II group (0.50 ± 0.27) were similar to the GP groups in the expression of p53 protein. No statistical difference was observed in the expression of p21 protein between the eight groups. Conclusion The upregulation of p53 protein expression in epidermal cells may be related to the mechanisms underlying the protective effect of 1.5% GP cream against photodamage. Key words: Gypenosides; Tumor suppressor protein p53