Hypoxia and TGF-β Drive Breast Cancer Bone Metastases through Parallel Signaling Pathways in Tumor Cells and the Bone Microenvironment
(A) Representative x-ray images from hindlimbs of mice 4 weeks post inoculation with MDA-MB-231 parental, shNT and shHIF cells. Arrows indicate osteolytic lesions. (B) Osteolytic lesion area measured on radiographs of hindlimbs and forelimbs of mice with bone metastases. Results are expressed as the mean area ± SEM per mouse (n = 5–10 per group). † P<0.01 and * P<0.001 compared to parental or shNT clones using a two-way ANOVA with a Bonferroni post-test at 4 weeks. (C) Kaplan-Meyer analysis of mouse survival. * P<0.05 shHIF#3 compared to Parental or shNT clones, † P<0.005 and ‡ P = 0.089 shHIF#11 respectively compared to Parental and shNT#7 using a Logrank test. (D) Representative histology of femurs with tumor indicated by arrows. Scale bar equal to 500 µm. (E) Tumor burden in hindlimbs was measured by quantitative histomorphometry. Results are expressed as the mean ± SEM area per bone. A one-way ANOVA with a Newman-Keuls multiple comparison test showed no significant differences (N.S.) between groups.