Figure 3.

Combination of proteasome and BET inhibitors results in exacerbation of the UPR. (A) BET inhibitors (JQ1 1 µM and I-BET762 10 µM) and proteasome inhibitor (CFZ 200 nM) were added either alone or in combination to A549, HCT 116, and MDA-MB-231 cells for 8 h, as indicated. DMSO was used as the vehicle control. RNA was isolated from these cells and subjected to quantitative RT-PCR to measure transcript levels of select stress response genes, as shown. The mRNA levels of 18s rRNA were used for normalization. Error bars denote SD (n = 3); (B) Cells treated as above were used for Western blot analysis employing specific antibodies as indicated and β-Actin was used as the loading control. The experiments were performed three independent times and a representative blot is shown; (C) A549, HCT116, and MDA-MB-231 cells were treated with BET inhibitors (JQ1 1 µM and I-BET762 10 µM) and proteasome inhibitor (CFZ 200 nM), similar as above, for 14 h and lysates were used to analyze cleaved caspase-3 using specific antibody. β-Actin served as the loading control. A representative blot of three independent experiments is shown. *, p < 0.05, **, p < 0.005, ***, and p < 0.0005 as compared with controls; #, p < 0.05, ##, p < 0.005, ###, and p < 0.0005 as compared with the CFZ-treated group.