Fig. 1

Characterization of the stemness properties of MB49 parental cells and MB49 F1 and S2 sub-clones. a Images showing differences in the morphology of MB49 parental, F1, and S2 cells. b CSC marker expression levels were compared among MB49 parental, F1, and S2 cells, with relative expression being normalized to MB49 parental cells. c MB49 cell sensitivity to CDDP and e gemcitabine was measured via MTT assay following treatment for 48 h with the indicated doses of these drugs (0, 0.03, 0.06, 0.125, 0.25, 0.5, 1, 2 µM). The absolute light absorbance at 540 nm was measured and normalized to vehicle control. d Determination of cell sensitivity to CDDP or f gemcitabine via clonogenic assay. Colonies were photographed and counted. g MB49 cell sphere formation assay. MB49 parental, F1 and S2 cells were cultured in serum-free CSC culture medium for 10 days and sphere images were taken on days 1 and 10 by phase-contrast microscope (50X). h Enhancement of CSC markers expression, as measured by qPCR, was observed when MB49 S2 were cultured in CSC medium. Relative expression levels were normalized to MB49 S2 cells in normal culture. Experiments were repeated independently at least three times. Data were compared via Student’s t-tests or one-way ANOVAs with Tukey’s multiple comparisons test, as appropriate. *P < 0.05; **P < 0.01; ***P < 0.001