1. EGFR is intrinsically active in FGFR3-activated cell lines with combination efficacy from targeting both EGFR and FGFR3.
EGFR is intrinsically active in FGFR3-activated cell lines with combination efficacy from targeting both EGFR and FGFR3. A, Western blot analyses of RT112M cells transfected 72 hours earlier with siCON or individual siRNA targeting EGFR (siEGFR-A/B). B, growth of RT112M cells transfected with siCON and two individual siRNA targeting EGFR (A and B) and 48 hours posttransfection exposed to a fixed dose of PD (+) or vehicle (−) for 72 hours. C, Western blot analysis of indicated cell lysates blotted for FGFR3, EGFR, and phosphorylated EGFR (P-EGFR), with actin loading control. The three FGFR3-activated cell lines are indicated. D, clonogenic survival assays in indicated cell lines treated continuously with 500 nmol/L PD (PD), 250 nmol/L gefitinib (Gef), the combination, or vehicle alone. Activating aberration in FGFR3 is indicated for each cell line, with cell lines classified as either partially FGFR3-dependent or primarily EGFR-dependent. Right, quantification of three independent experiments. E, analysis of S-phase fraction from propidium iodidie fluorescence-activated cell sorting profiles of indicated cell lines treated for 24 hours with 500 nmol/L PD173074, 250 nmol/L gefitinib, combination, or vehicle. *, P < 0.05, Student t test. F, expression of p27 increases with combination therapy at 24 hours, with a minor increase in cleaved PARP in 97-7 cells. DMSO, dimethyl sulfoxide.
Maria Teresa Herrera-Abreu et al. Cancer Discovery 2013;3:
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