Chk1磷酸化修饰及表达在FLT3-ITD阳性AML中的作用机制研究

Acute myeloid leukemia habouring FLT3-ITD pesents very poor prognosis. Recent studies demonstrate that replication stress is strongly enhanced by oncogenic transformation, the understanding of mechanisms that how cancer cells tame the catastrophic amouts of replication stress-derived DNA damage is important for discovering of new target therapy. Chk1 is a key regulator of replication stress, which was shown over-expressed in various human cancers. Our previous work has shown Chk1 facilitates leukemic cells proliferation down-stream of the onco-genic tyrosine kinase receptor FLT3-ITD. In this project, the molecular mechanism of Chk1 in the protection of leukemic cells is going to be studed by inhibiting of inducing Chk1 in FLT3-ITD positive cells, and be discussed if it would be by influencing the FLT3-ITD induced replication stress. Furthermore, this project can also clarify the importance of residue Ser280 in the Chk1 mediated FLT3-ITD protection signaling pathways, which will provide new insight into molecular mechanisms of the treatment of cancer cells with overexpressed replication stress through the inhibition of Chk1 pathways, and provide potential biomarkers of drug responsiveness.

FLT3-ITD阳性急性髓系白血病（AML）预后极差。近年来研究表明，癌变过程中致癌基因可诱发大量的DNA复制压力而对细胞的生存产生威胁，深入了解细胞逃逸复制压力所致毒性而获得急速增殖的机制将有助于我们发现新的抗肿瘤靶向治疗药物。Chk1是调控复制压力的关键激酶，已被证实在多数肿瘤中高表达。我们前期的工作表明Chk1影响FLT3-ITD 阳性AML细胞增殖。本项目拟以FLT3-ITD阳性AML细胞为研究对象，通过抑制和过表达Chk1，探讨Chk1在此类细胞中的表达及调控和保护机制，揭示Chk1是否通过调节DNA复制压力的相关信号通路影响携带FLT3-ITD突变的AML细胞的增殖。进一步通过影响Ser280的功能以阐明Ser280位点对Chk1介导的携带FLT3-ITD突变的AML细胞保护作用的影响，为FLT3-ITD阳性AML靶向治疗及疗效提供新的研究思路和理论依据。

目前尚不清楚在FLT3-ITD阳性急性髓细胞性白血病（AML）中CHK1的作用和机制。在这项研究中，我们研究了FLT3-ITD对CHK1 AML的调节作用以及CHK1在AML细胞存活中的作用。我们的结果阐明了FLT3-ITD阳性AML中的FLT3-ITD激活CHK1表观遗传机制。 CHK1在FLT3-ITD阳性AML中高表达。FLT3-ITD将p300募集到H3K27，随后将CHK1启动子乙酰化。干扰CHK1的表达可显着抑制MV4-11细胞的增殖并诱导其凋亡。此外，CHK1敲降促进了MV4-11细胞对表观遗传抑制剂JQ1和C646的敏感性。这项研究发现了FLT3-ITD + AML的新治疗靶点，并为表观遗传抑制剂联合治疗AML提供了依据。