Metformin Downregulates the Insulin/IGF-I Signaling Pathway and Inhibits Different Uterine Serous Carcinoma (USC) Cells Proliferation and Migration in p53-Dependent or -Independent Manners
Figure 2
Regulation of IGF-IR and IR promoter activities and transcriptional activators by metformin in USC cells.
USPC-1 and USPC-2 cells were transiently transfected with an IGF-IR promoter-luciferase reporter plasmid, p(-476/+640)LUC (A), or an IR promoter-luciferase reporter construct (B), along with a ß-galactosidase expression plasmid. Promoter activities were expressed as luciferase values normalized for ⇓-galactosidase activity. Results are mean ± SEM (duplicates samples of three independent experiments). *, p<0.05 versus untreated cells; **, p<0.05 versus USPC-2 cells transfected with IGF-IR or IR promoter luciferase constructs. C, Western blot analysis of Sp1, pTen, and p53 in USPC-2 and USPC-1 cells treated with metformin (24 h) and/or IGF-I (10 min). Whole-cell lysates (100 µg) were resolved by SDS-PAGE and immunoblotted with the indicated antibodies. Results are representative of three independent experiments.
