Figure 1.

The USP9X inhibitor WP1130 or G9 induces apoptosis more prominently in JAK2-V617F-dependent cells than in cells dependent on BCR/ABL or cytokine-activated JAK2. (A) HEL, PVTL-2, and K562 cells were treated with indicated concentrations of WP1130 for 24 h, and viable cell numbers were measured by the CCK-8 colorimetric assay. Each data point represents the mean of triplicate cultures, with error bars indicating standard errors, and is expressed as percentage of the cell numbers cultured without WP1130. The asterisks indicate significant differences between K562 and HEL or PVTL-2 determined by one-way ANOVA followed by Dunnett’s post-hoc test (* p < 0.05). (B) 32DE or UT7 cells transduced with either JAK2-V617F or empty vector (Control) and cultured with Epo were left untreated as control or treated for 24 h with 3 μM WP1130 (WP) or 2 µM G9, as indicated, in triplicate, and viable cell numbers were measured. The asterisks indicate significant differences between JAK2-V617F and control cells determined by Student’s t-test (* p < 0.05). (C) HEL, PVTL-2, and K562 cells were treated for 24 h with indicated concentrations of WP1130. Cells were analyzed for cellular DNA content by flow cytometry. Percentages of apoptotic cells with the sub-G1 DNA content are indicated. (D) 32DE/JAK2-V617F cells (JAK2-V617F) or vector-control cells (Control) cultured with Epo were treated for 5 h with indicated concentrations of WP1130 or G9 and analyzed.