Fig. 4.

Combined inhibition of ERBB family members and FGFR leads to synergistic impairment of the growth of HNSCC cell lines. (A) UMSCC25 cells were treated in triplicate with DMSO, 3.0 nM AZD8931, or 10 nM AZD8931 alone or in combination with 0.5 μM AZ8010 or 1.0 μM AZ8010. The effect of the treatments on cell growth was measured by clonogenic assay. (B) UMSCC25 cells were plated in triplicate and treated with DMSO, AZ8010, AZD8931, and the combinations at the doses shown. Proliferation was measured after 1 week by the CyQuant assay as described in the Materials and Methods and plotted on the top chart. Data are the means of two independent experiments. Combination indices (CIs) were calculated using the CalcuSyn (Biosoft, Cambridge, UK) program and shown on the bottom table where the strength of the synergism is indicated by the darkness of shading. (C) As in (A), except 584-A2 cells were treated with DMSO, 30 nM AZD8931, 30 nM AZ8010, and the combination. CCL30 cells were treated with DMSO, 100 nM AZD8931, 100 nM AZ8010, and the combination. The growth of 584-A2 cells was measured by clonogenic assay and the growth of CCL30 cells was measured using an anchorage independent growth assay as described in the Materials and Methods. (D) As in (A), except UMSCC1 and UMSCC8 cells were treated with DMSO, 30 nM AZD8931, 30 nM AZ8010, and the combination. Data are the means and S.E.M. of three independent experiments. Statistical analysis using a two-tailed t test showed significant differences in clonogenic growth. ns, not significant. *P < 0.05; **P < 0.005; ****P < 0.0001.