Figure 3

11PS04 impedes sphere formation. The frequency of oncosphere formation was measured by extreme limited dilution analysis (ELDA). (A,C) Sphere frequencies from MCF-7 and U87 single-cell suspensions are plotted against the number of cells seeded per well, showing a decrease in sphere formation in the presence of 11PS04: solid lines represent the estimated frequency and the broken lines are the 95% confidence intervals. The frequency of initiating sphere formation by cancer stem cells was calculated using the ELDA platform and a significant decrease in the frequency of oncosphere formation was produced by 11PS04 (P value < 0.001). (B,D) Representative phase-contrast images of mammospheres and gliospheres formed by day 15 (Scale bars 10 and 40 µm). (E) The frequencies obtained using mammary gland tumors from MMTV-neu^+/+ mice under the experimental conditions described in (A). (F) Representative phase-contrast images of mammospheres from MMTV-neu^+/+ mice formed by day 15 in the ELDA assay (scale bar 10 µm). (G) Relative survival of spheres obtained from CT2A xenograft tumors after 7 days in the presence of 11PS04. (mean ± SEM, n = 3, *P < 0.05, **P < 0.01). (H) Representative phase contrast images of the CT2A xenograft tumor spheres (scale bar 100 µm).