Figure 4.

Reporter analysis of the transcriptional activity of AP-1 and NF-κB in the MCF-7/Rap and MCF-7/T cells. The MCF-7/Rap (a,b) and MCF-7/T (c,d) cells were pretreated with or without 2 mM metformin for 2 days, then the cells were transfected with the AP-1 (a,c) or NF-κB (b,d) plasmid containing the luciferase reporter gene under the AP-1 or NF-κB-responsive elements, respectively, and β-galactosidase plasmid. Three hours after transfection the cells were treated with 2 mM metformin (MF) and 1 µM rapamycin (a,b) or 2 mM metformin and 5 µM tamoxifen (c,d) for 24 h. The luciferase and β-galactosidase activities were determined as described in Materials and Methods. p < 0.05: * versus respective control, # versus control cells w/o metformin. Data represent the mean value ± SD of three independent experiments.