Long-Term Alteration of Reactive Oxygen Species Led to Multidrug Resistance in MCF-7 Cells

Figure 3

Long-term treatment of H₂O₂ and GSH induced MDR in MCF-7 cells. MCF-7 cells were treated by replacing the culture medium every other day for 20 weeks. MDR to ADM or taxol was determined by MTT (a) and SBR (b) assays. Control: normal culture medium (i.e., MCF-7 cells); ADM: 0.1 μM ADM; ADM + GSH: 0.1 μM ADM + 2 mM GSH; ROS (L): 0.001 μM H₂O₂; ROS (M): 0.01 μM H₂O₂; ROS (H): 0.1 μM H₂O₂ (i.e., MCF-7/ROS cells); GSH (L): 0.001 μM GSH; GSH (M): 0.01 μM GSH; GSH (H): 0.1 μM GSH (i.e., MCF-7/GSH cells). Data represents the mean ± SD, . Significant differences relative to control group were indicated as and , and significant differences relative to ADM group were indicated as and .

(a)

(b)