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. Author manuscript; available in PMC: 2012 Feb 1.
Published in final edited form as: Clin Cancer Res. 2010 Nov 22;17(3):472–482. doi: 10.1158/1078-0432.CCR-10-0568

Figure 5. HGF rescues DiFi cells from cetuximab-induced apoptosis. HGF-dependent phosphorylation of MET reactivates AKT and MAPK in cetuximab-treated cells.

Figure 5

(A) DiFi cells were treated for 24 hours with serum-reduced media cetuximab (50 nM), cetuximab + HGF (75 ng/ml), and cetuximab + HGF + PHA-665752 (0.4 uM) followed by determination of cleaved caspase-3 levels, as described in Materials and Methods. Columns average of triplicates; bars SD; *, p < 0.0001. HGF rescues DiFi cells from cetuximab-induced apoptosis. MET inhibition with PHA-665752 restores pro-apoptotic effects of cetuximab in HGF-stimulated DiFi cells. (B) and (C) DiFi and LIM1215 cells were treated overnight with cetuximab (5 nM) and/or PHA-665752 (0.4 uM) with or without the addition of HGF (75 ng/ml) for the final 15 minutes. Whole-cell lysates were analyzed by SDS-PAGE, followed by Western blot. HGF-dependent phosphorylation of MET restored signaling through the AKT and MAPK pathways in cetuximab-treated cells. HER3 is not cross-activated by MET phosphorylation. A combination of cetuximab and PHA-665752 blocks the activation of AKT and MAPK by inhibiting MET and EGFR phosphorylation in HGF-stimulated cells.