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Figure 3 | Breast Cancer Research

Figure 3

From: Hypoxia-inducible factor 1α promotes primary tumor growth and tumor-initiating cell activity in breast cancer

Figure 3

Deletion of Hif1α decreases primary tumor growth. (A) Wild-type (WT) or knockout (KO) cells (n = 50,000) were transplanted into FVB/Nj mice. All tumors were harvested at day 56 to evaluate tumor weight, volume and burden (percentage tumor weight/total body weight, BW) (n = 10 recipients/genotype, P < 0.05, unpaired Student's t-test). (B) The growth rate of WT and KO tumors following transplant of 50,000 cells. Best-fit curves were established based on a polynomial fit algorithm using GraphPad Prism 4.0 software. Data in (A) and (B) are representative of seven independent experiments (> 60 recipients/genotype). (C) When 500 WT and KO cells were implanted into the mammary fat pad, the median time until 50% of recipients developed tumors > 500 mm3 was 64 days for WT mice and 127 days for KO mice (n = 14 recipients/genotype, P < 0.001, logrank test). (D) Western blot for HIF-1α in three independent tumors (500 to 750 mm3) per genotype. WT and KO cells that were cultured for 6 hours under hypoxic conditions served as positive and negative controls, respectively. CRM, cross-reactive material. MTEC, mammary tumor epithelial cell. (E) Mean fold change ± SEM in expression of HIF-1 targets in KO tumors as determined by qRT-PCR (n = 5 tumors/genotype). Decreased gene expression in KO tumors is presented as a negative fold-change relative to WT tumors. (F) An increase in Ki67+ cells in KO tumors is balanced by an increase in caspase 3-positive cells (n = 5 tumors/genotype, *P < 0.05, Student's t-test). Representative immunostaining images are shown in Additional file 2 Figure S4.

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