曲西立滨选择性抑制FLT3-ITD阳性急性白血病的新作用靶点发现及作用机制研究

The FLT3-ITD mutation, which is found in approximately 25% of AML patients, has been validated as a driver oncogene for AML. PKC412 (midostaurin) receives breakthrough therapy designation from the FDA for newly diagnosed FLT3-mutated acute myeloid leukemia (AML) recently. A variety of small molecule inhibitors, including the first generation multi-targeted kinase inhibitors sunitinib, sorafenib and lestaurtinib, and more selective second generation kinase inhibitors, such as AC220, crenolanib and PLX3397, have been tested in the clinic and have led to initial transient responses followed by development of resistance. One of the main resistance mechanisms is drug treatment-induced elevation of FLT3 ligand levels that can lead to the persistent activation of downstream mediators, such as AKT and ERK.. With High Throughput Screening, we identified the previously reported special AKT inhibitor, Triciribine, exhibiting high sensitivity against FLT3-ITD+ AML Cells but not FLT3 wide type AML cell lines. In addition, triciribine is also able to overcome FLT3 ligand-induced drug resistance in FLT3 wt /ITD co-expressing cells. However, these phenotypes were not observed with other AKT kinase inhibitors. The primary mechanistic study demonstrated that triciribine did not affect FLT3-ITD mediated signaling pathway. In addition, kinome wide targets searching with KinomeScan technology did not reveal any effective kinase targets, which lead us to postulated that triciribine might exert its anti-FLT3-ITD+ AML efficacy through other non-kinase targets. Hence, we propose to use pharmacological method combining multi-omics technology to study the mechanism of Triciribine’s selectively sensitive against FLT3-ITD+ AML meanwhile capability to overcome FLT3 ligand induced drug resistance, which presumably would provide a new drug discovery targets for this kind of disease.

FLT3-ITD阳性的急性髓性白血病(FLT3-ITD+AML)患者约占AML的25%左右。其主要发病机制是激酶FLT3基因发生FLT3-ITD突变使其持续活化，从而导致疾病的发生。在前期的研究中，我们发现AKT激酶抑制剂曲西立滨能够选择性的强烈抑制FLT3-ITD+AML细胞的增殖，同时可以克服FLT3配体升高所引起的此类药物耐药性问题，而其它AKT激酶抑制剂却没有类似的效果。初步药理学研究发现，曲西立滨不影响FLT3激酶介导的信号通路，而且激酶组检测没有发现曲西立滨其它激酶类有效作用靶点，这暗示曲西立滨很可能是通过其它有效靶点来对FLT3-ITD+AML起作用。因此，我们拟综合使用药理学和多组学的技术手段，探寻曲西立滨区别于其它AKT抑制剂能够有效抑制FLT3-ITD+AML的作用靶点，并初步验证新靶点的病理功能，为寻找药物开发的新靶点提供支持。

FLT3-ITD阳性急性髓性白血病(FLT3-ITD+AML)患者在急性髓性白血病中约占25%。研究表明，FLT3-ITD+AML主要的发病机制是由于激酶FLT3基因发生了FLT3-ITD突变使其持续活化。我们在前期研究中发现，AKT激酶抑制剂曲西立滨能够选择性的强烈抑制FLT3-ITD+AML细胞的增殖，同时可以克服FLT3配体升高所引起的此类药物耐药，而其它AKT激酶抑制剂却没有类似的效果。在本项目中，我们通过药理学研究发现，曲西立滨是通过靶向核转录因子STAT5阻断FLT3介导的信号通路而发挥作用。曲西立滨影响了STAT5的二聚阻断其进入细胞核中，从而有效的减少了细胞增殖相关的蛋白C-MYC、MCL-1和BCL-XL在细胞中的表达。STAT5和AKT的过度活化是临床上常见的引起FLT3-ITD突变细胞耐药的主要原因，鉴于曲西立滨具有同时靶向AKT和STAT5的作用，体外细胞模型及小鼠动物模型研究都展现出曲西立滨具有克服细胞耐药的作用。本研究为曲西立滨应用于FLT3-ITD+AML的治疗提供了理论和实验依据，并为克服FLT3-ITD+AML耐药提供了新的治疗策略。此外，我们还围绕FLT3-ITD+AML开展了一系列关于新药物、新机制和新靶点的发现研究工作，包括：针对AML研发了FLT3-ITD突变选择性新型FLT3激酶抑制剂CHMFL-FLT3-335和成药性良好的抑制剂CHMFL-FLT3-362；解析了已知药物全反式维甲酸治疗FLT3-ITD+AML的新机制；通过新型热休克蛋白HSP70抑制剂QL47，发现靶向HSP70是针对FLT3-ITD+AML的潜在治疗手段等。目前标注本项目的相关科研成果已发表SCI论文5篇，申请专利1项，并培养毕业博士研究生2名。

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