Fig. 3

Effect of MZ1 in combination with standard therapies and in vivo efficacy of MZ1 in JQ1-resistant tumors. a. Antiproliferative properties of the combination of MZ1 and cisplatin, docetaxel, and olparib evaluated by MTT metabolization. Parental and resistant cells (MDA-MB-231) were treated with MZ1 (0.05, 0.1, and 0.2 μM), cisplatin (2.5, 5, and 10 nM), docetaxel (0.125, 0.25, and 0.5 nM), and olaparib (2.5, 5, and 10 nM) for 72 h as single agents or in combination. Statistics analysis was performed between MZ1 and combination results. b. Effect of MZ1 in combination treatments: synergy studies. Combination index (CI) for the different drug combinations were obtained using CalcuSyn program from viability values obtained in an MTT assay after 72 h of incubation with the drugs. Combination doses used are the same than in A. CI values lower than 0,8 indicate a synergistic action. c. Representation of the tumor volumes (mm³) of MDA-MB-231R-derived tumors treated with either JQ1 (25 mg/kg) for 3 weeks or MZ1 (10 mg/kg) for 2 week, after a 1 week treatment with JQ1. Tumors volumes were calculated as follow: V = (L× W²)/2, where V = volume (mm³), L = length (mm), and W = width (mm). Mean of tumor volume ± SEM was represented. *p < 0.05; **p < 0.01; ***p < 0.005. d. Expression levels of BRD4 and BRD2 in TNBC JQ1-resistant derived tumors. Tumor samples from C were collected, washed with cold PBS, minced, and homogenized in lysis buffer. Protein expression levels were analyzed by Western blotting as described above. Calnexin was used as a loading control. Image J software was used for quantification