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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 3. HGF-dependent MET activation rescues LIM1215, DiFi, and GEO cells from cetuximab inhibition.

Figure 3

(A) DiFi, LIM1215, and GEO cells were treated with serum-reduced media and cetuximab (left panel 5nM, right panel 50nM) and increasing concentrations of HGF for 72 hours followed by determination of cell proliferation, as described in Materials and Methods. Data points average of triplicates; bars SD. HGF reverses inhibitory effects of cetuximab in tested cell lines. (B) Cell lines were treated with serum-reduced media, cetuximab (5 nM), cetuximab + HGF (75 ng/ml), and cetuximab + HGF + PHA-665752 (0.4 uM), followed by determination of cell proliferation at 24, 48, and 72 hours. Data points average of triplicates; bars SD. All three cell lines showed cetuximab-dependent inhibition of proliferation, which was reversed with HGF. Inhibition of MET with PHA-665752 abrogated the HGF rescue effect. (C) Left panel: LIM1215 cells were treated with serum-reduced media, cetuximab (5nM), cetuximab + HGF (75 ng/ml), cetuximab + HGF + non-silencing siRNA (5 ul/well), and cetuximab + HGF + MET siRNA (5 ul/well). Proliferation was determined after 72 hours. Columns average of replicates of six; bars SD; *, p < 0.0001. Right Panel: LIM1215 cells were treated with non-silencing siRNA and MET siRNA for 72 hours followed by determination of relative MET mRNA expression using RT-PCR. Columns average of triplicates; bars SD; *, p < 0.0001. Knocking down MET expression abrogates the HGF rescue effect and restores cetuximab’s inhibitory effects on cell proliferation.