BCL6 is induced in AML cells treated with chemotherapeutic agents. (A) Linear regression analysis showing correlation between basal BCL6 expression and sensitivity to AraC treatment in 11 different AML cell lines. (B) Linear regression analysis showing correlation between fold induction of BCL6 expression and sensitivity to AraC treatment (1.25 μM) using 11 different AML cell lines. Fold inductions in each of the cells were calculated based on mean fluorescence intensity (MFI) values by comparing treated vs untreated cells. (C-D) Induction of BCL6 in 4 different primary AML cells (AML54, AML74, AML95, and AML109) treated with AraC (111, 333, 1000, and 3000 nM, for 24 hours) in duplicates. Relative MFI of PE-BCL6 in each of the cells. The fold induction was calculated by normalization to untreated samples, and fractions of increase/decrease are presented. The data are plotted as averages of duplicates. Error bars indicate standard deviation. (E) Schematic illustration of BCL6 expression analysis after Ara C in vivo treatment of AML patient-derived xenografts. (F) Plot showing induction of BCL6 expression following engraftment of AML cells pretreated with AraC. (G) Analysis of BCL6 protein levels in AML cell lines treated with 6 different therapeutic drugs. BCL6 expression was evaluated by using flow cytometry. Rx, radiation.