Figure 2

Sunitinib treatment significantly inhibited tumor growth, tumor angiogenesis, and the proliferation of the claudin-low triple negative breast cancer. Oral sunitinib at 80 mg/kg/2 days for 4 weeks significantly suppressed the claudin-low TNBC growth curve of tumor volume (A) and tumor angiogenesis (B) in MDA-MB-231/xenografts. When the tumor volume reached around 500 mm3, four female athymic nude-Foxn1 mice received sunitinib given by gavage at 80 mg/kg/2 days for 4 weeks and the other 4 mice received the vehicle only as the control group. In the end, the tumor volume was significantly reduced by 94% (P < 0.01; n = 4) in the sunitinib-treated group in contrast to the control group, which was consistent with the inhibition of tumor angiogenesis (B). Sunitinib- treatment caused a significant decrease in average microvessel density (the number of microvessels per mm² area) of the claudin-low TNBC tumors when compared to the control tumors (68 ± 9 vs. 125 ± 16 microvessels number per mm²; n = 4; p < 0.01). 3H-thymidine incorporation assay indicated that sunitinib-treatment caused a dose-related inhibition on proliferation in cultured MDA-MB-231 cells, by 23% at 1 μmol/L, by 40% at 5 μmol/L, and 55% at 10 μmol/L, compared to the control group (n = 6; P < 0.01), respectively (C).