Figure 3

Pharmacological OGG1 inhibition results in telomere losses and post-mitotic defects. (A) Representative Telo-FISH images of an unaltered chromosome in metaphase stained with DAPI (in blue) with the corresponding telomeric signals (in green) at the end of each chromatid. Below, Representative Telo-FISH images of altered chromosomes showing telomere signal loss in one of the chromatids, multi-telomeric signals, and a micronucleus (orange arrows). (B) Quantification of telomeric signal-free ends for the indicated conditions in U2OS OGG1-GFP or OGG1-KO cells. Bars show the mean and the SEM for frequency events/metaphase (30 to 35 metaphases per condition from 2 independent experiments). Statistical significance was determined using unpaired, two-sided T-tests (**P < 0.01, ***P < 0.001 and ns: not significant). (C) Comparative analysis of the frequency of multi-telomeric signals for the indicated conditions in U2OS OGG1-GFP or OGG1-KO cells. Bars show the mean and the SEM for frequency events/metaphase (30 to 35 metaphases per condition from 2 independent experiments). Statistical significance was determined using unpaired, two-sided T-tests (P > 0.05, ns: not significant). (D) Comparative analysis of micronuclei formation frequency for U2OS OGG1-GFP incubated with DMSO or TH5487 and for OGG1-KO at basal conditions or during OS. More than 200 cells per condition were analyzed. Data is the average of 2 independent experiments. Significant differences were calculated using the Mann–Whitney test for non-parametric distributions (**P < 0.01, ***P < 0.001, **** P < 0.0001). (E) Up, comparative analysis for the colony area generated in each condition. Significant differences were calculated using the Mann–Whitney test for non-parametric distributions (**** P < 0.0001). Down, summary for the schedule of treatment to evaluate a specific clonogenic potential feature (area of colonies). Data are average of the mean colony area values of a single experiment.