Fig. 6: PX-866 induces proteasomal degradation of p21 in senescent cells. | Cell Death & Disease

Fig. 6: PX-866 induces proteasomal degradation of p21 in senescent cells.

From: Combined inhibition of class 1-PI3K-alpha and delta isoforms causes senolysis by inducing p21WAF1/CIP1 proteasomal degradation in senescent cells

Fig. 6

A, B Proliferating and senescent (day 7 after γIR) HCT116 cells were transfected with a non-targeting control siRNA or siRNAs directed against p53 or p21. 48 h after transfection, the cells were additionally treated with PX-866 (3 µM) for another 24 h. Cell death was assessed by quantifying LDH activity released into the cell culture supernatant (B), whereas inhibition of AKT phosphorylation and the knockdown of p53 or p21 protein expression was verified by western blotting (A). C–F Senescent (day 7 after γIR) HCT116 (C, D) or MCF-7 (E, F) cells were treated with either 3 µM PX-866, 10 µM MG-132 or a combination of both. At the indicated times, the cells were harvested and the cell extracts subjected to western blot analysis (C, E). The blots shown are representative of at least three independent experiments. The expression of p21 was quantified densitometrically using the Image Studio (Ver. 5.2) software (LI-COR). Relative p21 levels normalized to the no treatment sample (also indicated by a gray line) were plotted (D, F). Data shown are the mean ± SD of at least three independent experiments. Individual data points are represented in the bar charts by small black squares. ns not significant *p < 0.05, **p < 0.01, ***p < 0.001.

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