Department of Medicine, Division of Hematology, Center for Molecular Medicine (CMM) and Bioclinicum, Karolinska Institutet, Karolinska University Hospital Solna, Stockholm, Sweden.
Department of Medicine, Division of Hematology, Center for Molecular Medicine (CMM) and Bioclinicum, Karolinska Institutet, Karolinska University Hospital Solna, Stockholm, Sweden.
Biochem Biophys Res Commun. 2020 Jun 25;527(2):425-431. doi: 10.1016/j.bbrc.2020.04.058. Epub 2020 Apr 22.
The activating-mutation of JAK2V617F drives the development of myeloproliferative neoplasms (MPNs). Several JAK2 inhibitors such as ruxolitinib and gandotinib (LY2784544) currently in clinical trials and, provide improvements in MPNs including myelofibrosis. However, JAK2 inhibitors are non-curative and murine experiments show that JAK2 inhibitors don't eradicate MPN stem cells and it is currently unclear how they escape. We thus determined the effect of the specific JAK2V617F inhibitor LY2784544 on leukemic stem (CD34) cells (LSCs) using the JAK2V617F-bearing erythroleukemia cell line HEL. The LY2784544 treatment caused a transient proliferation inhibition and apoptosis of HEL cells, but a recovery occurred within a week. Thereafter, the continuous LY2784544 exposure induced the accumulation of CD34 LSCs, and the CD34 cells increased from 2% to >90% by week 9, which was accompanied by increased clonogenic potentials. LY2784544 was capable of stimulating CD34 expression even in CD34 HEL cells, which indicated cellular de-differentiation. A significantly enhanced expression of the stem cell factor KLF4 was observed in LY2784544-treated HEL cells. Inhibiting KLF4 expression attenuated LY2784544-mediated accumulation of CD34 LSCs. Moreover, the telomerase inhibitor GRN163L abolished the LY2784544-effect. JAK2 inhibitors thus cause enrichment of LSCs and are unlikely to cure MPN as a monotherapy. Simultaneously targeting JAK2V617F and KLF4 or telomerase may be a novel strategy for MPN therapy, which should be of significance both biologically and clinically.
JAK2V617F 的激活突变驱动骨髓增殖性肿瘤 (MPN) 的发展。目前正在临床试验中的几种 JAK2 抑制剂，如鲁索替尼和甘替尼（LY2784544），可改善 MPN 包括骨髓纤维化。然而，JAK2 抑制剂并非治愈性的，并且鼠类实验表明 JAK2 抑制剂不能根除 MPN 干细胞，目前尚不清楚它们是如何逃避的。因此，我们使用携带 JAK2V617F 的红白血病细胞系 HEL 来确定特异性 JAK2V617F 抑制剂 LY2784544 对白血病干细胞 (CD34) 细胞 (LSCs) 的影响。LY2784544 处理导致 HEL 细胞短暂的增殖抑制和凋亡，但在一周内恢复。此后，连续的 LY2784544 暴露导致 CD34 LSCs 的积累，CD34 细胞从第 9 周的 2%增加到>90%，这伴随着克隆形成潜能的增加。LY2784544 甚至能够刺激 CD34 在 CD34 HEL 细胞中的表达，这表明细胞去分化。在 LY2784544 处理的 HEL 细胞中观察到干细胞因子 KLF4 的表达显著增强。抑制 KLF4 表达减弱了 LY2784544 介导的 CD34 LSCs 的积累。此外，端粒酶抑制剂 GRN163L 消除了 LY2784544 的作用。因此，JAK2 抑制剂会导致 LSCs 的富集，作为单一疗法不太可能治愈 MPN。同时靶向 JAK2V617F 和 KLF4 或端粒酶可能是 MPN 治疗的一种新策略，这在生物学和临床上都具有重要意义。
