Figure 2. Knockdown of FOXA1 leads to a decrease in IGF-IR expression, independently of estrogen receptor, but does not inhibit IGF-IR signal transduction.

A) MCF7 cells were either transfected with non-specific siRNA (NS siRNA) or siRNA targeted to FOXA1 (FOXA1 siRNA). Cells were then lysed and protein was harvested, followed by western blot analysis as indicated. B) MCF7 cells were either transfected with NS siRNA, FOXA1 siRNA or IGF-IR siRNA. Cells were then lysed and RNA was isolated. Q-RT-PCR analysis was used to calculate relative mRNA expression as fold change compared to NS siRNA. The data are an average of three biological replicates ± SEM. A t-test analysis was performed comparing the NS siRNA group to the FOXA1 siRNA group (* p<0.05). C) C4–12 cells were transfected with either NS siRNA or FOXA1 siRNA. Cells were then lysed and protein was harvested, followed by western blot analysis as indicated. D) MCF7 cells were either transfected with NS siRNA or FOXA1 siRNA and either maintained in serum-free medium or treated with IGF-I (100ng/mL) for 30, 60 and 180 minutes. Cells were then lysed and protein was harvested, followed by western blot analysis as indicated. E) MCF7 cells were either transfected with NS siRNA or IGF-IR siRNA (siIGF-IR) followed by treatment with IGF-I (100ng/mL). Cells were then lysed and RNA was isolated. Q-RT-PCR analysis was used to calculate relative mRNA expression as fold change compared to NS siRNA. The data are an average of three biological replicates ± SEM. A t-test analysis was performed comparing the IGF-I treated group with the serum-free group (* p<0.05).