Abstract: Liu Mei, Zhou Chunlin, Zhu Hong, Jin Guangyu, Chen Hongduo, He Chundi. Key Laboratory of Immunodermatology of Ministry of Health; Department of Dermatology, First Affiliated Hospital of China Medical University, Shenyang 110001, China Corresponding author: He Chundi, Email: chundihe@hotmail.com 【Abstract】 Objective To investigate the effect of three Scutellaria baicalensis extracts （baicalin, baicalein and wogonin） on the apoptosis of a human cutaneous squamous cell carcinoma cell line, SCL-1. Methods Methyl thiazolyl tetrazolium （MTT） assay was performed to detect the proliferation of cultured SCL-1 cells treated with different concentrations （12.5, 25, 50, 75 and 100 μmol/L） of baicalin, baicalein and wogonin for various durations （12, 24 and 48 hours）. Some SCL-1 cells were treated with baicalin, baicalein and wogonin of 12.5 μmol/L respectively for 48 hours followed by the detection of cell apoptosis by double staining with annexin V-fluorescein isothiocyanate/propidium iodide in combination with enzyme-linked immunosorbent assay （ELISA）, as well as estimation of cell cycle by flow cytometry. The 50% inhibitory concentration was determined by line regression model and inner insert method, and statistical analysis was carried out by Student′s t test, one-way analysis of variance （ANOVA）, and Student-Newman-Keuls-q test. Results Baicalin, baicalein and wogonin all inhibited the proliferation of SCL-1 cells in a dose- and time-dependent manner （all P ＜ 0.01）. Under the same conditions （treatment concentration and duration）, baicalein showed the strongest inhibitory effect on the proliferation of SCL-1 cells, followed by wogonin and baicalin （all P ＜ 0.01）. All the Scutellaria baicalensis extracts induced the apoptosis of SCL-1 cells and arrested them in G1-phase. The percentage of cells in G1 phase was 56.37% ± 2.41%, 74.23% ± 2.02% and 64.15% ± 1.87%, and early apoptosis rate was 8.09% ± 1.02%, 24.13% ± 0.76% and 14.45% ± 1.57%, in SCL-1 cells treated with baicalin, baicalein and wogonin of 12.5 μmol/L for 48 hours, respectively, compared to 45.04% ± 1.93% and 4.12% ± 0.29% in the untreated control cells respectively （F = 83.29, 186.37, respectively, both P ＜ 0.01）. Similarly, there was a downward trend from baicalein to wogonin and baicalin in the effect on cell apoptosis and cell cycle arrest of SCL-1 cells. Conclusions Scutellaria baicalensis can inhibit the growth and induce the apoptosis of SCL-1 cells, which may provide new ideas for the treatment of cutaneous squamous cell carcinoma with traditional Chinese drugs.

Key words: Scutellaria baicalensis, Baicalin, Baicalein, Wogonin, Carcinoma, squamous cell, Apoptosis