Background: A major issue in Chronic Myeloid Leukemia (CML) is the persistence of quiescent leukemia stem cells (LSCs) in the hematopoietic niche under tyrosine kinase inhibitor (TKI) treatment. Results: Here, using CFSE sorting, we show that low-proliferating CD34+ cells from CML patients in 3D co-culture hide under HS27A stromal cells during TKI treatment—a behavior less observed in untreated cells. Under the same conditions, Ba/F3p210 cells lose their spontaneous motility. In CML CD34+ and Ba/F3p210 cells, while Rac1 is completely inhibited by TKI, RhoA remains activated but is unable to signal to ROCK. Co-incubation of Ba/F3p210 cells with TKI, SKF-96365 (a calcium channel inhibitor), and EGF restores myosin II activation and amoeboid motility to levels comparable to untreated cells, sustaining the activation of ROCK. In CFSE+ CD34+ cells containing quiescent leukemic stem cells, co-incubation of TKI with SKF-96365 induced the expulsion of these cells from the HS27A niche. Conclusions: This study underscores the role of RhoA in LSC behavior under TKI treatment and suggests that SKF-96365 could remobilize quiescent CML LSCs through reactivation of the RhoA/ROCK pathway.
背景：慢性髓系白血病（CML）治疗中的一个关键问题在于酪氨酸激酶抑制剂（TKI）治疗期间，静止的白血病干细胞（LSCs）在造血微环境中持续存在。结果：本研究通过CFSE分选技术发现，在三维共培养体系中，来自CML患者的低增殖性CD34+细胞在TKI治疗期间会隐匿于HS27A基质细胞层下，这种现象在未经处理的细胞中较少观察到。相同条件下，Ba/F3p210细胞的自发运动能力丧失。在CML CD34+细胞和Ba/F3p210细胞中，Rac1完全被TKI抑制，而RhoA虽保持激活状态却无法向ROCK传递信号。当Ba/F3p210细胞与TKI、钙通道抑制剂SKF-96365及表皮生长因子共孵育时，肌球蛋白II的激活和阿米巴样运动能力可恢复至未处理细胞水平，并维持ROCK的持续激活。在含有静止白血病干细胞的CFSE+ CD34+细胞中，TKI与SKF-96365联合处理可诱导这些细胞从HS27A微环境中迁出。结论：本研究揭示了RhoA在TKI治疗下LSC行为调控中的作用，并表明SKF-96365可能通过重新激活RhoA/ROCK通路，促使静止的CML LSCs重新动员。
肿瘤(癌症)患者之家