Chen Yuan, Zhao Hu, Luo Jing, Liao Youping, Tan Kui, Hu Guoyu
Department of Hematology, The Affiliated Zhuzhou Hospital Xiangya Medical College CSU, Zhuzhou, Hunan 412000, P.R. China.
Oncol Lett. 2021 May;21(5):351. doi: 10.3892/ol.2021.12612. Epub 2021 Mar 4.
Janus kinase 2 (JAK2) inhibitors, the first targeted treatments for myeloproliferative neoplasms (MPNs), provide substantial benefits, including a marked reduction in splenomegaly and MPN-associated symptoms. However, these drugs rarely induce molecular remission in patients with MPNs. Zileuton, a 5-lipoxygenase (5-LO) inhibitor, has been demonstrated to selectively deplete hematopoietic stem cells (HSCs) expressing a JAK2 point mutation (JAK2V617F) in mouse models of JAK2V617F-induced polycythemia vera (PV). To determine the potential activity of 5-LO inhibitors in combination with JAK inhibitors against human PV HSCs, the present study first analyzed 5-LO expression in CD34 bone marrow cells from patients with JAK2V617F-positive PV using western blotting and reverse transcription-quantitative PCR, and then examined the effect of zileuton combined with ruxolitinib on colony formation using a colony formation assay. Furthermore, cell cycle and apoptosis in CD34 cells from patients with PV and healthy volunteers were determined by flow cytometry. In the present study, 5-LO expression was upregulated in CD34 cells from patients with PV compared with in CD34 cells from healthy volunteers. Higher levels of leukotriene B4, a product of the 5-LO signaling pathway, were detected in patients with PV compared with in healthy volunteers. Zileuton treatment suppressed the colony formation of CD34 cells from patients with PV in a dose-dependent manner. Furthermore, zileuton and ruxolitinib exerted their anticancer effects by suppressing hematopoietic colony formation, inducing apoptosis and arresting the cell cycle of human CD34 cells from patients with PV. The combination of these two drugs exerted a more beneficial effect than either agent alone. Based on these data, zileuton enhanced the antitumor activity of low-dose ruxolitinib in hematopoietic progenitor cells from patients with PV, providing conceptual validation for further clinical applications of combination treatment with ruxolitinib and zileuton for patients with PV.
Janus激酶2（JAK2）抑制剂是骨髓增殖性肿瘤（MPN）的首批靶向治疗药物，具有显著疗效，包括脾肿大和MPN相关症状明显减轻。然而，这些药物很少能使MPN患者实现分子缓解。齐留通是一种5-脂氧合酶（5-LO）抑制剂，在JAK2V617F诱导的真性红细胞增多症（PV）小鼠模型中，已证明其能选择性消耗表达JAK2点突变（JAK2V617F）的造血干细胞（HSC）。为了确定5-LO抑制剂与JAK抑制剂联合使用对人PV HSC的潜在活性，本研究首先使用蛋白质免疫印迹法和逆转录定量PCR分析JAK2V617F阳性PV患者CD34+骨髓细胞中的5-LO表达，然后使用集落形成试验检测齐留通与鲁索替尼联合使用对集落形成的影响。此外，通过流式细胞术测定PV患者和健康志愿者CD34+细胞的细胞周期和凋亡情况。在本研究中，与健康志愿者的CD34+细胞相比，PV患者的CD34+细胞中5-LO表达上调。与健康志愿者相比，PV患者中检测到更高水平的白三烯B4（5-LO信号通路的产物）。齐留通治疗以剂量依赖性方式抑制PV患者CD34+细胞的集落形成。此外，齐留通和鲁索替尼通过抑制造血集落形成、诱导凋亡以及使PV患者的人CD34+细胞的细胞周期停滞来发挥抗癌作用。这两种药物联合使用比单独使用任何一种药物都具有更有益的效果。基于这些数据，齐留通增强了低剂量鲁索替尼对PV患者造血祖细胞的抗肿瘤活性，为鲁索替尼和齐留通联合治疗PV患者的进一步临床应用提供了概念验证。
