Figure 3.

Artesunate caused excessive mitochondrial ROS to induce cell senescence and inhibit cell proliferation. (A) Artesunate arrested cell cycle at G0/G1 phase in SW480 and HCT116. Cells were seeded in 6-well plates. Once attached, cells were maintained in FBS-free medium for about 16~24 h. Afterwards, cell were treated with artesunate (1, 2, and 4 μM in medium containing 10% FBS) for 72 h and then harvested for PI staining to analyze cell cycle by flow cytometry. (B) Artesunate induced cell senescence in SW480 and HCT116. Cells were seeded in 6-well plates and treated with artesunate (1, 2, and 4 μM) for 72 h. Cell senescence was represented via SA-β-gal activity, which was assayed using a SA-β-gal staining kit after artesunate treatment. (C) Artesunate treatment downregulated the protein levels of CDK 2/4/6 and upregulated the protein levels of CDKIs, p16, and p21 in SW480 and HCT116. Cells were seeded in 60 mm dishes and treated with artesunate (1, 2, and 4 μM) for 72 h. Then, cells were lysed with RIPA to extract total protein. The protein levels were measured by western blotting. The gray values of protein blots were evaluated by Image J. Relative protein expression was normalized to β-actin. (D) NAC attenuated the effect of artesunate on protein expression of p16 in SW480 and HCT116. NAC was used at a concentration of 2 mM and added alone or together with artesunate (4 μM) for 72 h. * p < 0.05, ** p < 0.01, and *** p < 0.001 vs. Ctrl. ### p < 0.001 vs. cells treated with artesunate alone. Data were shown as mean ± SD.