Figure 4. IGF1R-specific inhibition does not alter Taxol resistance.

(A) Combination treatment using Taxol and IMC-A12 in mice with HEY-T30 xenografts. HEY-T30 xenografts were grown as described in Figure 2D, then treated with Taxol (black circles), according to the same dose/schedule described in Figure 2D, or with IMC-A12 (intraperitoneal injection of 40 mg/kg three times per week, grey *), or with combination treatment of Taxol and IMC-A12 (grey x). Data points show the mean tumor volume±SEM for each treatment group (n = 8 animals per group). No significant differences in tumor volume were observed with IMC-A12 or combined Taxol/IMC-A12 treatment compared to D5W or Taxol alone. This experiment was repeated a second independent time with similar results. (B) Effect of IMC-A12 on Taxol sensitivity, evaluated by SRB cytotoxicity assay. In 96-well plates, cells were treated with serial dilutions of Taxol alone (solid lines) or together with a fixed dose of 10 µg/ml IMC-A12 (dashed lines). Dose response curves show the mean of the surviving fraction±SEM of cells relative to untreated cells at the indicated Taxol concentrations (n = 7 independent experiments, each done in six replicates). No significant Taxol sensitization was observed in the presence of IMC-A12. (C) Effect of NVP-AEW541 on Taxol sensitivity, evaluated by SRB cytotoxicity assay. In 96-well plates, cells were treated with serial dilutions of Taxol alone (solid lines) or together with a fixed dose of 1 µM NVP-AEW541 (dashed lines). Dose response curves show the mean±SEM of the surviving fraction of cells relative to untreated cells at the indicated Taxol concentrations. The bar graphs depict the IC₅₀ of Taxol for the indicated cell lines and drug treatments, and show the mean±SEM calculated from at least four independent experiments (each done in six replicates). NVP-AEW541 sensitizes A2780-T15 to Taxol. ***p<0.001, ****p<0.0001; One-way ANOVA with Bonferroni posttest. (D) ABCB1 (p-glycoprotein) function in HEY and HEY-T30 in the presence and absence of NVP-AEW541. Cells were incubated with labeled Taxol (Oregon Green 488 Taxol, bis-acetate) in the presence or absence of NVP-AEW541 or verapamil. The ABCB1-overexpressing HEY-T30 cells (light gray shaded graph) retain less labeled Taxol than HEY cells (unfilled black outline). Verapamil, a known p-glycoprotein inhibitor, markedly increases the retention of labeled Taxol in HEY-T30 cells (and to a lesser degree in HEY cells), as demonstrated by the rightward shift of the peaks. Shown in the right panel with the dashed black line, treatment with 1 µM NVP-AEW541 does not appear to affect retention of labeled Taxol in HEY-T30 cells. Two independent experiments were done with similar results.