Fig. 5: Knockdown or pharmacological inhibition of TIP60 decreases ΔNp63α and sensitizes cells to cisplatin.

A A431 Parental and A431 Pt B JHU029 and JHU006 were transfected with non-silencing control (NSC) siRNA or siRNA against TIP60 (siTIP60) and subjected to a 2-h cisplatin pulse treatment at the indicated doses. MTS was performed at 48-h post treatment. A431 Parental (control) and C Pt cells were treated with either vehicle or 100 μM NU9056, and D Pt cells were pre-treated with either vehicle or 75 μM TIP60 specific inhibitor TH1834 for 6 h. Cells were then subjected to a 2-h cisplatin pulse at the indicated doses and MTS was performed at 48-h post treatment. *p ≤ 0.05 compared to A431 Parental vehicle control and ^#p ≤ 0.05 compared to respective A431 Pt vehicle control at each dose of cisplatin. E Lenti A431-eGFP (control), ΔNp63α and TIP60 F Lenti JHU029-eGFP (control), ΔNp63α and TIP60 cells were subjected to a 2-h cisplatin pulse treatment at the indicated doses and MTS was performed at 24-h post treatment. *p < 0.05 compared to the Lenti-eGFP controls. Cell viability (y-axis) from an experiment representative of three independent experiments is shown in the top panels in A–F. The x-axis indicates the μg/μl concentration of cisplatin used for pulse treatment. Error bars indicate mean ±1SD from three technical replicates. Bar plots (middle panels in A–F) show the mean IC₅₀ + 1 SEM values calculated from three independent experiments. Immunoblot analysis (bottom panels in A–F) performed using antibodies specific for p63 and TIP60 is shown. Fold change in ΔNp63α protein relative to respective NSC or vehicle-treated control is listed above each band. β-actin was included as a loading control for equivalent protein.