Abstract: Liang Yinghong, Wei Ming, Liu Jia, Gong Yanjie, Tu Ling, Zhang Yihua Clinical Laboratory, Fifth Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China Corresponding author: Wei Ming, Email: gushiweiming@126.com 【Abstract】 Objective To investigate the of miRNA-203 in skin lesions of patients with psoriasis vulgaris, and to explore its effect on the proliferation of a human keratinocyte cell line HaCaT. Methods Lesional skin and adjacent non-lesional skin tissues were obtained from 23 patients with psoriasis vulgaris from 2014 to 2016. Fluorescence-based quantitative PCR was performed to determine the of miRNA-203 in these skin tissues. Targeted miRNA in skin tissues was in situ hybridized by using 5′ and 3′ digoxigenin-labelled probes, so as to localize the of miRNA-203 in skin tissues. Cultured HaCaT cells were divided into 3 groups: miRNA-203 mimic group and negative control group transfected with miRNA-203 mimics and negative control miRNA-203 respectively, and blank control group receiving no treatment. Methyl thiazolyl tetrazolium （MTT） assay, flow cytometry and Western blot analysis were performed to investigate changes in cellular proliferative activity, cell cycle and its related proteins Cyclin D1 and Cyclin B1 in HaCaT cells respectively. Results MiRNA-203 was specifically expressed in epidermal keratinocytes. Besides the cell nuclei, it could be expressed in the cytoplasm. In the patients with psoriasis vulgaris, the of miRNA-203 was significantly higher in lesional skin tissues than in non-lesional skin tissues （1.35 ± 0.28 vs. 0.52 ± 0.09, t = 6.76, P = 0.012）. The transfection with miRNA-203 mimics could significantly inhibit the proliferation of HaCaT cells （F = 9.36, P = 0.007）. Additionally, the blank control group, negative control group and miRNA-203 mimic group all showed a gradual increase in proliferative activity of HaCaT cells over time （F = 18.68, P < 0.001）. HaCaT cells were arrested in G2/M phase in the miRNA-203 mimic group with the percentage of cells in G2/M phase being 31.33% ± 4.56%, compared to 17.02% ± 3.53% in the negative control group （P < 0.05） and 16.67% ± 3.32% in the blank control group （P < 0.05）. Moreover, the miRNA-203 mimic group showed significantly higher protein of Cyclin D1 （1.15 ± 0.13）, but significantly lower protein of Cyclin B1 （0.43 ± 0.08）, compared with the negative control group （0.52 ± 0.05, 0.93 ± 0.16, respectively, both P < 0.05） and blank control group （0.56 ± 0.07, 0.91 ± 0.0.15, respectively, both P < 0.05）. Conclusion MiRNA-203 may participate in the occurrence and development of psoriasis vulgaris.

Key words: Vulgaris, psoriasis, MicroRNA, Keratinocyte cells, Cell proliferation