Figure 1.
IGF-I stimulated PDK1 activity in MCF7 and T47D cells.
Breast cancer cell lines MCF7 and T47D were cultured in normal growth media (supplemented with 10% FBS) or serum starved for 24 hours. Growth factors EGF (A), TNFα (B), IGF-I (C), or insulin (D) were added to the culture media for 15 minutes after starvation. Cells were subsequently harvested and lysed, and lysates were subjected to SDS-PAGE. Western blot analysis was performed to examine the phosphorylation levels of AKT and p70S6K. GAPDH was included in each western blot analysis as a protein loading control.
Figure 2.
PDK1 inhibitor PF-5177624 decreased IGF-I induced AKT and p70S6K phosphorylation.
All IGF-1 stimulation experiments were subject to serum starvation for 24 hours prior to compound treatment or IGF-1 addition. MCF7 and T47D cells were stimulated with IGF-I at various time points, and phosphorylation levels of IGFR-I, AKT and p70S6K were determined (A). The structure of PF-5177624 is shown in (B). MCF7 or T47D cells were pre-treated with the PDK1 inhibitor, PF-5177624 at 0.2 uM, 1 uM, or 5 uM for two hours prior to stimulation with IGF-I as noted. Cell lysates were prepared and subjected to SDS-PAGE. Western blot analysis were performed to determine the phosphorylation levels of IGFR-I, AKT, and p70S6K (C), as well as PARP cleavage (E). (D) Cells were cultured in a 96-well microtiter plate and treated with PF-5177624. After two hours of compound treatment, cells were stimulated with IGF-I (15 minutes) and cell lysates were analyzed by pAKT (T308) ELISA assay to determine the IC50 value of PF-5177624. The data shown for the cell treatments and western blots analysis are representative of at least two experiments.
Figure 3.
PF-5177624 blocked IGF-I induced cell cycle progression in MCF7 and T47D cells.
Cells were serum-starved for 24 hours in order to synchronize cells at the G0/G1 stage. Cells were pre-treated with DMSO or PF-5177624 for 2 hours prior to addition of IGF-I for 6, 18, 24, 48, or 72 hours. Cells were subsequently harvested, fixed, and stained with PI and cell cycle profiles were obtained by flow cytometry. Bar graphs indicating the percentages of cells in the various cell cycle stages at the 72 hour time point are shown in (A) and (B). Phosphorylation of Histone H3 was determined on cells treated with 5 µM PF5177624 for 24, 48, and 72 hours and normalized to DMSO treatment at the same time points as shown in (C). MCF7 and T47D cells were also incubated with BrdU and subject to FACS to measure incorporation of new DNA. The fold decrease of BrdU incoporation relative to DMSO treatment at the same time point are shown in (D). The t-test was performed to determine if there were differences in samples treated with compound versus DMSO at the same time point; * = p<0.05, ** = p<0.001, *** = p<0.005.
Figure 4.
PF-5177624 inhibited cell proliferation and cell transformation in MCF7 and T47D cells.
Cells were cultured in complete medium and treated with PF-5177624 for 72 hours prior to addition of rezasurin to determine the IC50 value of cell proliferation inhibition by PF-5177624 (A). Soft agar assays were performed in MCF7 (B and C) and T47D cells (D and E). The images from representative dishes and microscopy are shown to demonstrate colony numbers and morphology (B and D). Colony numbers were also counted (C and E).