Fig. 1: Phenotypic alterations distinguish drug tolerant persister cells (DTPs) from treatment-naïve cells.

A Treatment-naïve (Naïve) and DTP-derived (DTP) cell clones were treated with cisplatin for 48 h and cell death (Annexin V/PI) was analyzed by flow cytometry. Cell clones were categorized as sensitive or non-sensitive relative to the combined average of cell death in control and DTPs cell clones. B Colony formation assays of naïve and DTP cell clones after exposure to cisplatin. Based on the plating efficiency, the surviving fraction was calculated by counting the number of colonies formed from adherent cells in the presence (13 μM for 4 h) or absence of cisplatin. C Cells were seeded at identical density and a scratch was introduced. Cell migration was assessed by measuring the closed distance after 24 h. Dots represent the mean of biological triplicate analyses per clone, lines represent mean ± SD of all clones. D–F Microscopy reveals pseudopodia-like structures (red arrows) in DTPs that are not present in naïve or parental OVCAR-3 cells. All pictures were taken with the same magnification; the bar represents 200 µm. *p < 0.05; **p < 0.01; ***p < 0.001; ****p < 0.0001.