Will et al.: Apoptosis induced by JAK2 inhibition is mediated by Bim and enhanced by the BH3 mimetic ABT-737 in JAK2 mutant human erythroid cells
Will, B; Siddiqi, T; Alberich Jordà, M; Shimamura, T; Luptakova, K; Staber, PB; Costa, DB; Steidl, U; Tenen, DG; Kobayashi, S.
Apoptosis induced by JAK2 inhibition is mediated by Bim and enhanced by the BH3 mimetic ABT-737 in JAK2 mutant human erythroid cells.
Blood. 2010; [Fulltext] [PubMed]
- The activating mutation JAK2 V617F plays a central role in the pathogenesis of polycythemia vera (PV), essential thrombocythemia, and primary myelofibrosis. Inhibition of JAK2 activity leads to growth inhibition and apoptosis in cells with mutated JAK2. However, the pro-apoptotic proteins involved in JAK2 inhibition-induced apoptosis remain unclear. In this study, we show that JAK2 inhibition-induced apoptosis correlated with up-regulation of the non-phosphorylated form of the BH3-only protein Bim in hematopoietic cell lines bearing JAK2 mutations. Knockdown of Bim dramatically inhibited apoptosis induced by JAK2 inhibition, which was reversed by the BH3 mimetic agent ABT-737. In addition, ABT-737 enhanced the apoptosis induced by JAK2 inhibition in JAK2 V617F+ HEL and SET-2 cells. The combination of JAK Inhibitor I and ABT-737 reduced the number of erythroid colonies derived from CD34+ cells isolated from JAK2 V617F+ PV patients more efficiently than either drug alone. These data suggest that Bim is a key effector molecule in JAK2 inhibition-induced apoptosis and that targeting this apoptotic pathway could be a novel therapeutic strategy for patients with activating JAK2 mutations.