Figure 6. Aurora B inhibition in a Myc overexpressing medulloblastoma flank xenograft model.

A) Flank tumors were established in female nude mice by subcutaneous injection of UW426-Myc cells in a matrigel matrix. At 24 days post tumor cell implantation, mice were randomized to receive vehicle or 25 mg/kg/day AZD1152-HQPA x 4 days. Tumors were excised and frozen in liquid nitrogen on the 5^th day for Western blot analysis. Western blot shows inhibition of Aurora kinase B target Histone H3 Serine 10 (pH3 Ser10) and inhibition of autophosphorylation of Aurora B at threonine 232 (pAurB) in tumors from animals that received AZD1152-HQPA. Total protein loaded was 30 μg. B) H&E stain of flank UW426-Myc tumors in mice that received either vehicle or AZD1152-HQPA 25 mg/kg/day x 4 days. Scale bar 100 μm. C) Immunohistochemistry for Histone H3 Serine 10 phosphorylation and cleaved caspase-3 in UW426-Myc flank tumors from mice treated with vehicle (n=7) or AZD1152-HQPA (n=5). Graphs represent cell counts in more than 1000 cells per tumor per condition, *P<0.05. Scale bars 100 μm. D) Flank tumor mass on day 29 after tumor cell implantation in animals that received 50 mg/kg twice daily for 2 days starting on day 14 after cell implantation. Median and interquartile range depicted (Vehicle, n=7; AZD1152, n=10). E) Flank tumor volume in mice treated with vehicle (circles, n=6) or AZD1152-HQPA (squares, n=10) at 50 mg/kg day twice daily for 2 days starting on day 14 after tumor cell implantation. Tumor volumes are significantly different (P<0.05) from 4 days after treatment onwards.