Figure 6. Effect of silencing TP53 on genome instability in PA-1 cells after ETO treatment. PA-1 cells were treated with 8 µM ETO for 20 h, then washed and examined at the indicated time points for the (A) the proportion of normal (2 centrosomal; 2 cen), ≥ 4 cen bipolar and ≥ 4 cen multipolar mitoses and (B) micronucleation. (A) Cells were treated as before and then examined by IF staining for pCHK2 and α-tubulin. Silencing of TP53 caused multi-centrosomal mitoses (≥ 4 cen) that were mostly multi-polar or showed coalescence of centrosomes in two poles. (B) Cells were treated as before and then assessed for the extent of micronucleation following DNA in situ staining. An increase in the proportion of interphase cells with micronuclei was observed in response to ETO treatment. Silencing of TP53 significantly increased the amount of micronucleation, which was further enhanced in response to ETO (p < 0.05). Data are representative of three independent experiments.