Three Scutellaria baicalensis extracts induce the apoptosis of a human cutaneous squamous cell carcinoma cell line SCL-1: an experimental study

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 μ mol/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