Figure 3
CD44hi/CD24lo A4 cells are significantly more resistant to conventional chemotherapeutic reagents, but are more sensitive to salinomycin treatment than CD44hi/CD24− G4 cells. (A) Relative reduction in proliferation of A4 and G4 cells after treatment with various chemotherapeutics in at least four different concentrations for 96 h, as determined by an MTT proliferation assay. Three independent experiments were performed, and a representative experiment is shown. *p < 0.01. (B) Phase contrast pictures of G4 versus A4 treated for 10 d with 0.4 or 1 µmol/L doxorubicin, respectively. The arrows show dead Tryphan blue-stained cells. (C) CD24 expression of HMT3909S13 as shown by flow cytometry after treatment with 0.4 µmol/L doxorubicin, 40 µmol/L methotrexate, 5 µmol/L paclitaxel or 2 µmol/L salinomycin for 10 d, showing a selection of doxorubicin-methotrexate- and paclitaxel-treated cells that express more CD24 compared with untreated cells. No selection is observed with salinomycin treatment.