Figure 2. Coexistent PIK3CA mutation is associated with decreased dependency on MEK signaling for tumor growth in vitro and in vivo.
A: Immunoblots showing the effects of MEK inhibition in PD0325901 sensitive (SW620, H747) and resistant (HCT-15, DLD-1) cell lines. Cells were treated with 50nM PD0325901 and lysates immunoblotted with the specified antibodies.
B: MEK-dependent (SW620, H747) and MEK-independent (HCT-15, DLD-1) cells were treated with 50nM PD0325901 or DMSO control and harvested 48 hours later. Graphs show: (Top) the percent of cells with G1 DNA content and (Bottom) the apoptotic fraction reported as the percent of cells with sub-G1 DNA content. The results represent the mean ± SE of two independent experiments done in triplicate.
C: MEK-dependent (SW620, H747) and MEK-independent (HCT-15, DLD-1) cells were treated with PD0325901 in a soft agar colony formation assay. Representative images at 21 days post plating are shown.
D: Mice with established SW620 and HCT15 xenografts were treated with PD0325901 × 5 days/week, for 3 weeks, or with vehicle only. The results represent the mean percent increase in tumor volume ± SE (n = 5 mice/group).