Abstract: TIAN Li-ming, XIE Hong-fu, LI Ji, YANG Ting*, HU Wei, PENG Yuan. *Department of Dermatology, Nanhua Hospital, University of South China, Hengyang 421002, Hunan, China 【Abstract】 Objective To observe the effect of high expression of β-catenin on senescent phenotypes in normal human skin fibroblasts （NHSFs） induced by hydrogen peroxide （H2O2）. Methods Cultured NHSFs were classified into three groups: β-catenin + H2O2 group transfected with a recombinant plasmid pcDNA3.1-β-catenin and treated with H2O2 of 150 μmol/L for two hours, H2O2 group transfected with the empty vector pcDNA3.1 and treated by H2O2 of 150 μmol/L for two hours, and vector group transfected with the empty vector pcDNA3.1 and receiving no treatment. Reverse transcription （RT）-PCR and Western blot were performed to quantify the mRNA and protein expressions of β-catenin in these cells, microscopy to observe the morphological changes of cells. The activity of senescence-associated β-galactosidase （SA-β-Gal） and superoxide dismutase （SOD） as well as the level of reactive oxygen species （ROS） were detected by using commercial kits. Data were processed with the software SPSS 13.0, and analysis of variance （ANOVA） was conducted for multiple group comparisons. Results The expression of β-catenin was significantly upregulated in NHSFs transfected with the recombinant plasmid pcDNA3.1-β-catenin. Both the mRNA and protein expression levels of β-catenin described as β-catenin/glyceraldehyde-3-phosphate dehydrogenase （GAPDH） ratio were significantly lower in the H2O2 group compared with the vector group （0.2900 ± 0.0195 vs. 0.5963 ± 0.0400, 0.3130 ± 0.0171 vs. 0.6190 ± 0.0090, both P < 0.05）, while the protein expression level of β-catenin was statistically higher in the β-catenin + H2O2 group than in the H2O2 group （0.7953 ± 0.0074 vs. 0.3130 ± 0.0171, P < 0.05）. Significant differences were observed between the vector group, H2O2 group and β-catenin+ H2O2 group in the percentage of SA-β-gal-positive cells （（2.9667 ± 0.2517）% vs. （37.70 ± 0.9539）% vs.（29.330 ± 0.6359）%, P < 0.05）, ROS activity （（50.9963 ± 9.2688）% vs. （109.9190 ± 11.5215）% vs.（75.1063 ± 3.0138）%, P < 0.05） , and SOD levels （（88.0856 ± 3.9181） vs.（35.5585 ± 3.4438） vs.（61.7029 ± 3.1716） U/mg, P < 0.05）. Conclusion The overexpression of β-catenin can downregulate the activity of SA-β-Gal and ROS level, but enhance the activity of SOD. 【Key words】 Beta catenin; Hydrogen peroxide; Fibroblasts; Oxidative stress; Cell aging

Key words: Hydrogen peroxide