Abstract:

Liu Saijun*, Guo Meiyan, Deng Liehua, Zhao Gang, Hu Yunfeng, Yi Min, Wu Shi. *Department of Dermatology, First Affiliated Hospital of Jinan University, Guangzhou 510630, China Corresponding authors: Deng Liehua, Email: liehuadeng@126.com; Guo Meiyan, Email: guomei04@163.com 【Abstract】 Objective To evaluate the effect of selenomethionine （Se-Met） against ultraviolet B （UVB）-induced oxidative damage to human HaCaT keratinocytes, and to explore its possible mechanisms. Methods Cultured HaCaT cells were divided into several groups: normal control group receiving no treatment, Se-Met groups treated with Se-Met at concentrations of 1, 10, 50, 100, 200 nmol/L and 1 μmol/L for 24 hours respectively, UVB groups irradiated with UVB of 30, 60 and 90 mJ/cm2 respectively, Se-Met + UVB groups treated with Se-Met at concentrations of 1, 10, 50, 100, 200 nmol/L and 1 μmol/L for 24 hours firstly, then irradiated with UVB of 30, 60 and 90 mJ/cm2 respectively. Subsequently, methyl thiazolyl tetrazolium （MTT） assay was performed to estimate cellular proliferative activity, flow cytometry to detect cell apoptosis, colorimetry to evaluate superoxide dismutase （SOD） and glutathione peroxidase （GSH-Px） activities and to determine malondialdehyde （MDA） levels. Statistical analysis was carried out by using factorial design analysis of variance （ANOVA）, one-way ANOVA and least significant difference （LSD） test. Results Factorial design ANOVA showed that UVB radiation had an inhibitory effect on the proliferative activity of HaCaT cells （F = 128.04, P < 0.05）, which significantly decreased along with the increase of UVB doses, with significant differences between the three UVB groups （P < 0.05）. Se-Met pretreatment also affected cellular proliferative activity （F = 5.95, P < 0.05）, which was significantly increased in Se-Met （10 nmol/L - 1 μmol/L） + UVB groups compared with the UVB groups at corresponding doses （all P < 0.05）. There was no significant interaction effect on cellular proliferative activity between UVB radiation and Se-Met pretreatment （F = 1.65, P > 0.05）. The apoptosis rate of HaCaT cells in the 30-mJ/cm2 UVB group was 31.9% ± 2.67%, significantly higher than that in the normal control group （4.1% ± 0.67%, P < 0.05） and in the 10-, 50-, 100-, 200-nmol/L and 1-μmol/L Se-Met + 30-mJ/cm2 UVB groups （21.9% ± 3.72%, 17.2% ± 1.67%, 4.6% ± 0.85%, 7.5% ± 1.86% and 13.5% ± 1.95% respectively, all P < 0.05）. Similarly, SOD and GSH-Px activities were significantly weaker （both P < 0.05）, while MDA levels were higher （all P < 0.05） in the 30-mJ/cm2 UVB group than in the normal control group; however, there was a significant increase in SOD and GSH-Px activities but a decrease in MDA levels in the Se-Met （10 nmol/L - 1 μmol/L ） + 30-mJ/cm2 UVB groups compared with the 30-mJ/cm2 UVB group （all P < 0.05）. Conclusions Se-Met can reduce UVB-induced oxidative damage to HaCaT cells, likely by enhancing antioxidase activity and decreasing oxygen radicals.