e14099 Background:The identification of a targeted therapy for patients with triple-negative breast cancer (TNBC) is one of the most urgent needs in breast cancer therapeutics. Since the p53 gene is mutated in approximately 80% of TNBC patients, it is a potential therapeutic target for this form of breast cancer. PK11007 is a 2-sulfonypyrimidine that stabilizes and reactivates mutant p53 (Bauer et al, PNAS 2016). The compound recently was reported to preferentially decrease viability in p53-compromised cancer cells. The aim of this investigation was to evaluate PK11007 as a potential new treatment for TNBC. Methods: Cell viability was determined using the MTT assay. Apoptosis was detected using Annexin V Apoptosis Detection Kit. Migration was determined by Transwell migration assay. Knockdowns of p53 protein were carried out using predesigned Flexitube sequences (Qiagen). Results: IC50 values for inhibition of proliferation by PK11007 in the panel of 17 breast cell lines ranged from 2.3 to 42.2 μM. There were significantly lower IC50values for TNBC than for non-TNBC cell lines (p = 0.03) and for p53-mutated cell lines compared with p53 WT cells (p = 0.003). Response to PK11007 however, was independent of ER or HER2 status of the cells. In addition, PK11007 induced apoptosis and inhibited migration in p53 mutant cell lines. Using RNAseq and gene ontogeny analysis, we found that PK11007 altered the expression of genes enriched in pathways involved in regulated cell death, regulation of apoptosis, signal transduction, protein refolding and locomotion. To establish if PK11007 acts by targeting mutant p53, we used siRNA to knockdown p53 in 3 p53-mutated TNBC cell lines. Reduction in p53 protein levels resulted in a significant decrease in the growth inhibitory effects of PK11007, in all 3 cell lines investigated, suggesting that PK11007 mediates growth inhibition via p53. The observations that PK11007 inhibited cell growth, induced apoptosis, blocked cell migration and altered genes involved in cell death, are all consistent with the ability of PK11007 to activate mutant p53. Conclusions: Based on our data, we conclude that targeting mutant p53 with PK11007 is a potential approach for treating p53-mutated TNBC.
The p53 Protein Influences the Sensitivity of Testicular Germ Cells to Mono-(2-Ethylhexyl) Phthalate-Induced Apoptosis by Increasing the Membrane Levels of Fas and DR5 and Decreasing the Intracellular Amount of c-FLIP1
