Figure 2.

Effects of BET inhibitors JQ1 and PFI-1 on proliferation of AtT20 cells. JQ1 and PFI-1 significantly reduced proliferation of AtT20 cells, when compared to untreated (UT) cells, DMSO-only treated cells and JQ1-treated cells. Proliferation was assessed using CellTiter Blue assays after 96 h treatment with 1 µM of each compound. Control treatments are represented by black bars and test compound treatment by white bars (A). Dose escalation studies using 20 nM, 50 nM, 100 nM, 500 nM and 1 µM JQ1 or PFI-1 and their effects on proliferation of AtT20 cells after 96 h treatment. The EC₅₀ value is indicated by a solid line. Responses to JQ1 (filled squares and solid line), JQ1- (filled circles and broken line) and PFI-1 (filled triangles and broken line) are shown (B). The efficacy of the BET inhibitors JQ1 and PFI-1 was further examined by time course analysis of cell proliferation after a single treatment with 1 µM JQ1 or PFI-1. Cells were treated with 1 µM JQ1-, JQ1 or PFI-1 and proliferation measured every 24 h and up to 96 h following treatment. Control treatments are represented by dashed lines and drug treatments by solid lines (C). After 96 h treatment with 1 µM JQ1-, JQ1 or PFI-1, compounds were removed (indicated by the arrow) and AtT20 cells culture in standard culture media. Proliferation was measured every 24 h for the following 96 h (D). For all experiments, significance is relative to DMSO vehicle only treatment with (A) ***P < 0.0005 and in (B, C and D) PFI-1 statistics represented by the symbol § and JQ1 statistics by *; ^§/*P < 0.05, ^§§/**P < 0.005 and ^§§§/***P < 0.0005. For all experiments untreated (UT), vehicle only (DMSO) and JQ1- were used as negative controls, and experiments were performed in n = 4 biological replicates, with four technical replicates per experiment.