Fig. 4

Susceptibility of TOP1 cleavage-ligation to CPT and TDP1 in nuclear extracts for eight selected BC cell lines. a Efficiency of the TOP1 cleavage-ligation step was measured in nuclear extracts isolated from selected cultured cells after incubation with DMSO (control) or 60 μM CPT using the REEAD assay. Intensity of the REEAD signal obtained when measuring TOP1 activity in the presence of CPT was normalized to the signal obtained in DMSO for each cell line (REEAD signal in CPT/REEAD signal in DMSO). Results were plotted as mean ± SD (four independent experiments). Yellow bars - Luminal cell lines; blue bars - HER2 cell lines; orange bars - TNBC cell lines. b Bar charts of TDP1 activity measured in cell extracts from selected cell lines. TDP1 activity measured in terms of fluorescence signals was plotted as average ± SD (three independent experiments). Yellow bars - Luminal cell lines; blue bars - HER2 cell lines; orange bars - TNBC cell lines