Figure 5

Combined targeting of pure and mixed-cell pure luminal (pLUM) and pure luminobasal (pLB) colonies with fulvestrant/gefitinib. (A) Pure pLUM, pLB or 1:1 and 5:1 pLUM:pLB mixtures were grown as three-dimensional Matrigel colonies in the absence of hormones for 48 h. Colonies were switched for 5 days to media containing no drug (days 1 to 5); 1 uM gefitinib (days 4 to 5); 100 nM ICI (days 1 to 5); or both (ICI days 1 to 5; gefitinib days 4 + 5). Colonies were treated with bromodeoxyuridine (BrdU), processed for immunohistochemistry (IHC) and a BrdU proliferation index was quantified. Data are average of triplicates ± standard error of the mean (SEM). *P ≤0.05; **P ≤0.01, ***P ≤0.001, ****P ≤0.0001, ns, not-significant. (B) Same as A except MCF-7 cells were substituted for pLUM. (C) 1:1 mix of pLUM:pLB cells was injected into cleared fat pads of ovariectomized non-obese diabetic/severe combined immunodeficient (NSG) mice and tumors were grown 6 weeks without hormones. Mice were treated 10 days with no drug (Control), fulvestrant (ICI), gefitinib or both. Tumor volumes are expressed as % volume on treatment day 0, for ≥4 tumors ± SEM at each time point.