Fig. 1.

Bone marrow-derived factors promote breast cancer stem cell colony formation. a Bone marrow conditioned media (CM) from three individual patients increased mammosphere colony formation in 5/6 breast cancer cell lines (ER+; oestrogen receptor positive, ER−; oestrogen receptor negative) compared to control treatment. Representative photomicrographs of mammospheres formed by MCF-7 and MDA-MB-231_BH cells treated with control media (CONT) and CM are shown. Scale bar 100 µM. b CM increased mammosphere colony formation in 15/17 early breast cancer (EBC) samples. Error bars represent six technical replicates for each sample. Representative photomicrographs of mammospheres formed by one sample treated with control and CM are shown. Scale bar 100 µM. c Response to CM did not differ when samples were grouped by ER status (n = 9 ER+, 8 ER−). d CM increased mammosphere self-renewal in four early breast cancer samples. e CM treatment did not increase the percentage of ALDH+ cells in the MCF-7 cell line. Examples of representative FACS plots are shown. f Mammosphere formation of MCF-7 cells increased ex vivo when cells were grown intra-femorally, compared to cells grown in vitro or subcutaneously in vivo, and this increase in mammosphere formation was lost following growth of isolated cells on plastic (shown at passage 2, (P2)). g CM did not increase the ability of MCF-7 cells to migrate. Data is presented as percentage wound closure following 18 h in culture, adjusted for wound size. Representative images of cells at 0 and 18 h shown. Scale bar 200 µM. Dashed line shows wound edge at 18 h. All graphs represent mean ± SEM, *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001