Figure 4. Co-targeting of IGF-1R and Ras signaling overrides the resistance to IGF-1R TKI driven by the K-Ras mutation in vitro and in vivo.

(A) Relative cell survival of mut Ras, resistant NSCLC cells after treatment with an IGF-1R TKI (PQIP, 5 µM), a MEK inhibitor (PD98059 [10 µM] or U0126 [2 µM or 1 µM]), or both. (B) Effect of combined IGF-1R and MEK inhibition on anchorage-independent colony-forming ability of NSCLC cells with mut Ras. The indicated NSCLC cells seeded in soft agar were treated with PQIP (1 µM), U0126 (2 µM), or both. Ad-MEK-DN, dominant negative form MEK expressing adenovirus ; Ad-EV, empty adenovirus. The relative colony numbers are shown. (C) Synergistic apoptotic effect of combined treatment with PQIP (5 µM) and U0126 (1 µM) on apoptosis of mut K-Ras-H157 NSCLC cells. The active form of caspase-3 was stained, and the percentage of apoptotic cells is plotted. (D) Mice bearing H226B-K-Ras xenograft tumors (2 tumors per mouse, 4 or 5 mice per group) were treated with vehicle (control), OSI-906 (40 mg/kg, once a day), U0126 (4 mg/kg, every other day), or both OSI-906 and U0126 as indicated. Day 0 represents the first day of drug treatment. Data are means and 95% confidence intervals. (E) IHC staining of the xenograft tumors in (D) with Ki67 and cleaved caspase-3 antibody was performed, and results are shown for at least 4 tumors in each group.