Figure 1 from Oncogenic Mutant <i>p53</i> Sensitizes Non–Small Cell Lung Cancer Cells to Proteasome Inhibition via Oxidative Stress–Dependent Induction of Mitochondrial Apoptosis

<p>Onc-p53 regulates basal levels of 20S proteasome activity and is required for BTZ-induced cytotoxicity in NSCLC cells. <b>A,</b> 20S proteasome activity was determined in the indicated cell lines using a fluorometric proteosome activity assay and plotted as mean fluorescence units (MFU). All pairwise comparisons were made using the Student <i>t</i> test. <b>B,</b> (Left) Relative 20S proteasome activity in lysates of H1975-Control vs. H1975-p53KO cells. (Right) Cell lysates of H1975-Control and H1975-p53KO (p53KO) cell lines generated using CRISPR/Cas9 were immunoblotted with p53 and GAPDH antibodies. <b>C,</b> The indicated cells were treated with vehicle or increasing concentrations of BTZ (left) or CFZ (right) for 72 hours, and cell viability was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. A paired <i>t</i> test was performed to analyze differences in viability among the cell lines. <b>D,</b> (Left) H1975-Control or H1975-p53KO cells expressing GFP or p53^R273H were treated with BTZ (5 nmol/L) for 48 hours, and cell viability was determined by trypan blue exclusion assay. (Right) Lysates of the indicated cell lines were immunoblotted with p53 and GAPDH antibodies. <b>E,</b> (Left) H460 or H460-p53KO (<a href="#bib18" target="_blank">18</a>) cells were treated with vehicle (−) or BTZ (5 nmol/L) for 72 hours, and cell viability was determined by WST-1 assay. (Right) Cell lysates of H460 and H460-p53KO cells were immunoblotted with p53 and GAPDH antibodies. <b>F,</b> (Left) H460-p53KO cells stably expressing GFP or p53^R273H were treated with increasing concentrations of BTZ for 72 hours, and cell viability was determined by WST-1 assay. (Right) Cell lysates of H460-p53KO cells stably expressing GFP or p53^R273H were immunoblotted with p53 and GAPDH antibodies. *, <i>P</i> < 0.05; **, <i>P</i> < 0.01; ***, <i>P</i> < 0.005; ns, <i>P</i> > 0.05. Error bars indicate ± 1.0 SD.</p>

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Author Eziafa I Oduah Medicine, Medical Oncology