Supplementary Figure 7: Additional data for Fig. 7.

(a) TP53 silencing or targeting with SAHA (Vorinostat) or PRIMA-1 sensitizes TNBC but not WT p53 cell lines to the proteasome inhibitor Carfilzomib (CFZ). Viability post 24 h treatment is shown. (b) Drug-mediated inhibition of proteasome and mutant p53 synergistically decreases the proteasome activity in MDA-MB-231 cells. (c) 24 h treatment of MDA-MB-231 cells with SAHA (2,5 μM), PRIMA-1 (1 μM) or APR-246 (1 μM) plus the proteasome inhibitor Carfilzomib (CFZ; 12.5 nM) induces tumour suppressive proteins KSRP, PUMA, p21 and NOXA (latter 3 are WT p53 targets) and the apoptosis marker PARP p85 increase. Representative of 2 repeats; (d) Simultaneous administration of PRIMA-1 and the proteasome inhibitor Carfilzomib (CFZ) inhibits the growth of primary xenograft tumours more effectively than a combination of SAHA and CFZ. Means of n = 4 animals with s.e.m. are shown, ANOVA test with Bonferroni correction: *P < 0.05,**P < 0.01, ***P < 0.001; (e) Concomitant treatment of MDA-MB-231 cells with Carfilzomib (CFZ) and APR-246 eliminates Carfilzomib resistant colonies while combining CFZ or APR-246 Cisplatin, Doxorubicin or Paclitaxel does not increase their toxicity. Means of two independent experiments; (f) Introduction of mutant p53 variants to MCF10A cells with stably silenced WT p53 increases their resistance to proteasome inhibitor Carfilzomib (CFZ) but sensitizes them to the CFZ + APR-246 combination (viability, 24 h treatment). Means of two independent experiments; (g) Mutant TP53, NRF2 silencing or APR-246 (PRIMA-1MET) treatment reduces the proteasome genes PSMA2 (left graph) and PSMC1 (right graph) transcript increase due to the bounce-back effect post treatment with Carfilzomib (CFZ) in TNBC cell lines. Means of of two independent experiments; (h) Primary MDA-MB-231-Luc (mutant p53, TNBC) subcutaneous xenograft growth in SCID mice is significantly reduced compared to the DMSO (caliper measurement, means of n = 8 independent animals with s.e.m. are shown, significance for the time-course is indicated—Friedman nonparametric matched pairs test with Dunn’s correction; ***P < 0.001). (a, b) Means of n = 3 biologically independent samples with s.d. are shown, ANOVA test with Bonferroni correction: *P < 0.05, **P < 0.01, ***P < 0.001; Unprocessed original scans of blots are shown in Supplementary Fig. 9. Statistics source data for 7a-b, d-g provided in Supplementary Table 10.