Fig. 1

HT-29/EGFP/FUR cells are resistant to 5-FU, exhibit altered morphology and decreased proliferation. a HT-29/EGFP/FUR cells stably resistant to 5-FU were developed by exposing cell line HT-29/EGFP to gradually increasing concentrations of this chemotherapeutic till stable proliferation in concentration of 2 μg/ml. The chemoresistant cells, and in vivo-derived (FURiv) cells were used for subsequent analysis. b The chemoresistant cells (here referred to as FUR) exerted reduced apoptosis. The decreased proportion of apoptotic cells was determined by Annexin V assay. Cells positive for Annexin V are apoptotic, positivity for DAPI stands for necrotic ones. Mann-Whitney U test was used for statistical analysis. c Chemoresistant cells are 135-fold more resistant to 5-FU than parental counterparts HT-29/EGFP as evaluated by luminescence viability assay after 6-days-long treatment. Values were expressed as means of quadruplicates ± SD. Mann-Whitney U test was used for statistical analysis. d Fluorescent images from IncuCyte ZOOM™ kinetic imaging system documented altered cellular morphology and formation of colonies of chemoresistant cells stained with NucLight™ Red (referred to as FUR/NLR) when compared to parental cell line (also stained with red nuclei protein; HT-29/NLR). Scale bar: 200 μm. e Immunocytochemical staining of F-actin showed morphological differences between chemoresistant and parental cells. Magnification × 630. f Based on counting of the confluence by the kinetic imaging system we have shown that the proliferation rate of HT-29/EGFP cells and their chemoresistant counterparts significantly differ. SD are below resolution of the picture. Student’s t-test was used for the statistical analysis