Fig. 6

p53 transcriptionally repressed CDC20 expression by directly binding to CDC20 promoter. A Dual-luciferase reporter gene assay was conducted to verify whether p53 could regulate CDC20 promoter activity (TSS-1495 bp ~  + 26 bp). The results implied that p53 overexpression in 293 T cells could significantly inhibit CDC20 promoter activity. Relative luciferase activity was expressed as the ratio of firefly luciferase activity to renilla luciferase activity. Data were obtained from three independent experiments and presented as mean ± SD. ***P < 0.001. B CUT&Tag assay proved that p53 directly bound to CDC20 promoter region at TSS-492 bp ~  + 101 bp. Compared with the untreated control group, CDC20 promoter signal was significantly decreased in Z138 cells treated with 5 μM nutlin-3a for 24 h. The red box indicated the binding site of p53 on CDC20 promoter on chromosome 1, and the characteristic signal peaks of the control group (upper) and nutlin3a-treated group (lower) in this region. C Z138 cells were pre-treated with 15 μM PFT-α for 1 h, and then co-treated with 50 μM apcin for 24 h. WB results showed pre-treatment of Z138 cells with PFT-α could rescue CDC20 expression reduced by apcin treatment. Data were obtained from at least three independent experiments and presented as mean ± SD. **P < 0.01, ***P < 0.001, ns meant P > 0.05