Fig. 1. Breast CAFs, but not NFs, protect some TNBC lines from chemotherapy.

a MDA-MB-231-luc cells were cultured alone (0% fibroblasts) or with increasing proportions of immortalised breast NFs (left panel) or CAFs (right panel). Cultures were treated with three different doses of epirubicin as shown, or with vehicle control for 24 h. Cultures were incubated for a further 48 h in fresh medium, before survival of MDA-MB-231 was assessed using luciferase assays. Data represent survival after epirubicin relative to matched vehicle control cultures, and are means (±SE) of three independent experimental replicates. b MDA-MB-231-GFP/luc (top panels) or MDA-MB-468-GFP cells (bottom panels) were cultured alone (0% fibroblasts) or with increasing proportions of immortalised breast NFs or CAFs. Cultures were treated with 10 nM epirubicin or vehicle control for 24 h. Epithelial cells were then collected by FACS and clonogenic survival was determined. Data are presented as colony counts (left panels) or relative survival after epirubicin (colony counts after epirubicin relative to matched untreated cultures; right panels). Data represent means (±SE) of three independent experimental repeats. c MDA-MB-231-GFP/luc cells were cultured alone (0% fibroblasts) or with increasing proportions of primary (p) breast NFs or CAFs cultured from a triple negative breast cancer resection. Cultures, cells and data were treated as for part B. Data represent means (±SD) of technical duplicates from one experimental repeat. Statistics: linear regression was carried out for analyses in A and B, with selected significant differences in the overall trend across the fibroblast proportions shown (ns not significant). ANOVA tests were performed in addition; these also demonstrated that CAFs provided significant protection from epirubicin in MDA-MB-231 cells (p < 0.01; lowest dose Fig. 1a and Fig. 1b right panel) and not in MDA-MB-468 cells.