Supplementary Figure 3: Microvascular endothelium protects basal breast tumour cells from other therapies and luminal/ER⁺ breast tumour cells from doxorubicin.

T4-2 cells were seeded on bone marrow stroma or on bone marrow MVNs, as described in Fig. 2a, and treated with increasing doses of 5-FU or lapatinib. Dose response of T4-2 ‘DTCs’ to 5-FU on bone marrow a) stroma and b) MVNs (n = 3 independent experiments). NS denotes no significance, whereas * P = 0.020 and ** P = 0.005 by one-way ANOVA and Dunnett’s multiple comparison test, comparing the indicated dose to vehicle treatment. The percentage of TUNEL-positive cells was quantified across n = 3 independent experiments for c) stroma and d) MVNs. NS, no significance, *** P < 0.0001 by one-way ANOVA and Dunnett’s post-test compared to vehicle treatment. Dose response of T4-2 cells to lapatinib on bone marrow e) stroma and f) MVNs (n = 5 independent experiments). NS, no significance, * P = 0.038, ** P = 0.0038 by one-way ANOVA and Dunnett’s post-test, compared to vehicle treatment. g) The percentage of TUNEL-positive cells was quantified across n = 3 independent experimentsfor g) stroma and h) MVNs. NS, no significance, *** P < 0.0001 when comparing the condition indicated to vehicle by one-way ANOVA and Dunnett’s post-test. Dose response of MCF-7 breast tumour ‘DTCs’ to doxorubicin on bone marrow i) stroma and j) MVNs (n = 5 independent experiments). NS, no significance, * P = 0.0373, *** P = 0.0007 when comparing the indicated condition(s) to vehicle (0 nM) by one-way ANOVA and Dunnett’s post-test. TUNEL intensity within YFP⁺ tumour cells/cell clusters was quantified on bone marrow k) stroma and l) MVNs across n = 3 independent experiments. *** P < 0.0001. Indicated P values obtained by unpaired two-tailed t test. For TUNEL analyses, the number of cells (predominantly single cells and clusters of 2–4 cells) analyzed across n = 3 independent experiments is stated within each panel. For a-l, centre line represents the mean, error bars the s.e.m. Statistical tests and P values are indicated. Source data are provided in Supplementary Table 1.