Apigenin Induced Apoptosis by Downregulating Sulfiredoxin Expression in Cutaneous Squamous Cell Carcinoma

Figure 5

Apigenin induced cell apoptosis and inhibited the expression of Srx via regulating the MAPK signaling pathway in cSCC. (a, b) TPA-induced JB6 cells (a) and A431 cells (b) were treated with the combination of apigenin and inhibitor of MEK1/2, Binimetinib (5 or 10 nM), for 8 h. Western blotting was used to analyze the expression of Srx, p-Erk, and the apoptosis-related proteins BAX and Bcl2. Representative images are shown on the left. The bar graph on the right indicated the intensity quantification of the protein band relative to GAPDH or total protein (ERK). Significant difference was designed by ANOVA, , , and vs. control (TPA-induced sample as control for JB6 cells). (c) Real-time PCR was conducted to quantify the mRNA expression of Srx in cSCC cell lines while cells were treated for indicated compounds. and vs control by ANOVA analysis. (d) Representative images of cell apoptosis analysis by flow cytometry after 5 nM Binimetinib (MEK1/2 inhibitor) treatment for 24 h, respectively, in TPA-induced JB6 (up) and A431 (down). The percentage of apoptosis cells after apigenin treatment with or without Binimetinib is shown in the bar graph. vs. control by ANOVA analysis. (e, f) TPA-induced JB6 (e) and A431 (f) were incubated with or without the MEK1/2 inhibitor (5 nM Binimetinib) for 24 h in the presence of 80 μM apigenin. Whole-cell lysates were subjected to western blotting to detect the apoptosis-associated proteins caspase 3, caspase 8, and PARP. The bar graph showed the intensity quantification of the protein bands from each treatment. Significant difference was designed by ANOVA, and vs. the apigenin-alone group.

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