Fig. 1
Cell lines serving as models for EMT-mediated resistance. a Growth of parental (black) and resistant (red) cells upon exposure to the drugs they were rendered resistant to, at concentrations estimated to inhibit the growth of parental cells by 50% (IC50, Table 1). Growth is calculated relative to cells unexposed to the drugs. Shown are individual data points and means of experiments performed in triplicate (except for the pair HCC4006P1 and HCC4006ER, n = 6), each replication consisting of nine technical replicates. Significance of the difference between parental and resistant cell growth is according to a one-sided Mann-Whitney U test. b Example of morphological changes associated with EMT, showing a parental epithelial cell line (HepG2) and two derived resistant mesenchymal cell lines (HepG2S1 and HepG2S3). c Expression differences (log2 fold-change) of common EMT markers, vimentin (VIM), N-cadherin (CDH2), E-cadherin (CDH1), and epithelial cell adhesion molecule (EPCAM), between resistant and parental cells. Names of resistant lines indicate cell line pairs. d Cell surface expression of EPCAM protein in a parental (HepG2) and two resistant cell lines (HepG2S1 and HepG2S3), measured using flow cytometry. Shown are signal intensities of APC-conjugated anti-EPCAM antibody (x-axis, log10 scale) and forward scatter area (FSC-A; y-axis, linear scale). e Expression changes in EMT marker genes following resistance acquisition. Boxplots illustrate expression differences (log2 fold-change) between resistant and parental cells of 16 epithelial (gray) and 34 mesenchymal (red) marker genes (Additional file 1: Table S1), determined using RNA sequencing. Significance of differences between epithelial and mesenchymal marker gene expression changes was calculated using a two-sided Mann-Whitney U test. f As in panel (E) for cells transfected with miRNA-200, determined using RT-qPCR. g As in panel (a) for cells transfected with miRNA-200, relative to miRNA-200 transfected cells unexposed to the drugs. For all cell line pairs: n = 6, except for HCC827P and HCC827GR: n = 3. ns non-significant, *p value < 0.05, **p value < 0.01, ***p value < 0.001, ****p value < 0.0001