JQ1 treatment impairs growth and induces apoptosis of human T-ALL cell lines. (A) JQ1 treatment inhibits human T-ALL cell line growth. Human T-ALL cell lines were cultured with vehicle or increasing concentrations of JQ1 (100-1000 nM) for 5 days and growth and metabolism assayed by MTS. The absorbance levels were normalized to the vehicle control and the GI₅₀ of each cell line was calculated using Graph Pad Prism 5 software. The results are averages of 3 to 5 independent experiments and error bars represent SEM. (B) JQ1 treatment reduces C-MYC expression in human T-ALL lines. Human T-ALL lines were cultured with DMSO or JQ1 (1 μM) for 24 hours and C-MYC expression levels quantified by quantitative PCR. C-MYC expression was normalized to β-ACTIN and calculated using the ΔΔCT method. The results are averages of 3 independent experiments and error bars represent SEM. ***P < .001 for all JQ1-treated cell lines. (C-D) JQ1 induces apoptosis of human T-ALL lines. (C) KOPTK1 and Jurkat cell lines were treated with DMSO or JQ1 (1 μM) for 96 hours and the apoptotic cells detected by Annexin V and 7AAD staining followed by flow cytometry. A representation fluorescence-activated cell sorter plot is shown. (D) Collated data of Annexin V–positive cells from 7 human T-ALL cell lines treated with vehicle or JQ1 (1 μM) for 96 hours. The results are averages of 3 to 5 independent experiments and error bars represent SEM. *P < .05, **P < .01, ***P < .001.