Notch信号通路抑制剂联合FLT3抑制剂是靶向治疗FLT3-ITD阳性急性髓系白血病的新策略？

Single drug FLT3 inhibitor(tyrosine kinase inhibitor,TKI)has been unable to meet the clinical needs of FLT3-ITD+AML; TKI synergizing with new target drugs is a more sensible treatment. We firstly found that the Notch signaling pathway inhibitor combining with TKI shows a more significantly antitumor effect than the single drug TKI in FLT3-ITD+AML. Since the Notch signaling pathway is a key factor that sustains the characteristics of leukemia stem cell(lsc), whether the Notch signaling pathway combining with TKI would be a new strategy for therapy of FLT3-ITD + AML? Would the mechanism of the antitumor effect interfere with LSC?To answer these questions, the project is going to validate the expression of Notch signaling pathway of FLT3-ITD+AML treated with TKI from the GEP database,clinical samples and LSCs. It would be evaluated that the antitumor effect and the ability to clear LSC of FLT3-ITD+AML treated with the TKI and Notch signaling pathway inhibitor in cell lines，animal models and clinical samples. The mechanism of the effect of these drugs on LSC would be explored by RT-PCR Array.After completed this project, it would provide a new strategy for clinical FLT3-ITD+AML treatment.

单药FLT3抑制剂TKI已经无法满足FLT3-ITD+AML的临床治疗需要；TKI联合新的靶向药物才是更为明智的治疗方式。我们首次在FLT3-ITD+AML发现Notch信号通路抑制剂联合TKI较单药TKI比有更明显杀瘤作用。由于Notch通路是维持白血病干细胞（LSC）特性的关键通路，那么，Notch通路抑制剂联合TKI是否能成为FLT3-ITD+AML治疗的新策略？其作用机制是否是干预LSC呢？本项目从表达谱数据库、临床标本、LSC水平等验证TKI作用的FLT3-ITD+AML中，Notch通路靶基因的表达变化；从细胞系、动物和临床等多个层面拟评估TKI联合Notch信号通路抑制剂对FLT3-ITD+AML的杀瘤作用和清除LSC的效应；通过RT-PCR Array芯片方法初步探讨其该药物联合应用对LSC影响的机制并加以验证。完成本项目，将为临床治疗FLT3-ITD+AML提供新策略。

FMS样酪氨酸激酶3的内部串联重复（Internal tandem duplication mutations of FMS-like tyrosine kinase-3，FLT3/ITD）突变是急性髓系白血病（acute myeloid leukemia，AML）中最常见的遗传改变并预后不良。FLT3酪氨酸激酶抑制剂（TKI）在FLT3/ITD+AML中应用，可出现早期的缓解，但对生存期无明显改善。Notch信号转导通路在许多类型的肿瘤细胞中都很重要，但在FLT3/ITD+AML中的作用仍有待阐明。在我们的研究中，我们发现Notch信号通路在经FLT3-TKI处理后的FLT3/ITD+细胞系和原代细胞中被激活。同时，我们检测了FLT3-TKI和Notch信号通路的抑制剂γ-分泌酶抑制剂（γ-secretase inhibitors，GSI）对FLT3/ITD+AML抗肿瘤作用和探索其潜在的分子机制。结果，我们观察到双药联合使用对FLT3/ITD+AML细胞系和原代AML细胞中降低细胞增殖并诱导凋亡。此外，原代FLT3/ITD+AML移植的老鼠模型中，FLT3-TKI和GSI的联合使用可清除动物模型中白血病细胞并延长了AML老鼠模型的生存期。从分子机制上讲，通过FLT3/ITD+AML细胞系表达谱差异分析，我们发现CXCR3可能通过ERK信号通路在该双药联合作用中起到一定协同作用。我们的研究结果表明，FLT3-TKIs与GSI的联合治疗可作为一种潜在的FLT3/ITD+AML的治疗策略。