Allosteric Modulators of Src-family Kinases for Acute Myeloid Leukemia

摘要 哺乳动物Src家族的八个成员是非受体蛋白酪氨酸激酶，它们参与了近 所有的细胞信号通路。Hck和Fgr是该家族的成员，几乎仅在髓系中表达。 造血细胞及其祖细胞。这些激酶的过度表达与 急性髓性白血病（AML）的发展和预后较差。AML是一种常见的血液 成年人的癌症，在美国每年有近20，000例新发病例。大约三分之一的AML病例有激活 Flt 3受体酪氨酸激酶的突变，包括点突变和内部串联重复。电流 这类AML患者的治疗包括ATP位点激酶抑制剂，尽管获得性耐药 突变通常在开始治疗的一年内发生。Hck和Fgr的抑制剂也是 作为AML治疗的新方法而出现。我们的研究小组最近发现了一些小分子， 与激酶结构域的ATP结合位点相反，Hck的调节结构域（独特-SH 3-SH 2-接头）。 结合数据和对接模型表明，这些化合物结合到一个需要特定3D- SH 3和SH 2结构域的构象。它们还降低AML细胞系的活力， 过表达活性Hck和Fgr。基于这些结果，我们假设这些化合物抑制 通过SH 3和SH 2结构域干扰下游信号传导来抑制AML细胞生长。此外该 化合物可以变构地影响活性位点的构象以有利于ATP位点抑制剂作用。我们 旨在扩大这些发现，使用体外激酶和结合试验，探索Src- 激酶家族以及与ATP位点抑制剂可能的协同作用。抗AML的作用机制 化合物将在AML细胞系模型中通过将它们对激酶活性和下游的影响相关联来测试。 底物活化与生长抑制和凋亡。最后，我们将确定这些的结合位点 通过X-射线晶体学确定Hck内的假定变构抑制剂。这些实验将提供关键的见解 对于这些新化合物作为AML治疗的未来开发，无论是作为独立治疗，还是 与现有的ATP位点抑制剂组合。 1

Abstract The eight mammalian Src-family members are non-receptor protein-tyrosine kinases which are involved in nearly all cell signaling pathways. Hck and Fgr are members of this family expressed almost exclusively in myeloid hematopoietic cells and their progenitors. The overexpression of these kinases has been linked to the development of, and a poorer prognosis in, acute myeloid leukemia (AML). AML is a common form of blood cancer in adults, with nearly 20,000 new cases per year in the US. About one-third of AML cases have activating mutations in the Flt3 receptor tyrosine kinase, including point mutations and internal tandem duplications. Current treatments for this subset of AML patients include ATP-site kinase inhibitors, although acquired resistance mutations commonly develop within one year of the start of treatment. Inhibitors for Hck and Fgr are also emerging as a new approach to AML therapy. Our group recently identified small molecules that bind to the regulatory domains of Hck (unique-SH3-SH2-linker) as opposed to the ATP-binding site of the kinase domain. Binding data and docking models suggest that these compounds bind to a site that requires a specific 3D- conformation of the SH3 and SH2 domains. They also decrease the viability of an AML cell line that overexpresses active Hck and Fgr. Based on these results, we hypothesize that these compounds suppress AML cell growth by interfering with downstream signaling via the SH3 and SH2 domains. In addition, the compounds may allosterically influence the conformation of the active site to favor ATP-site inhibitor action. We aim to expand upon these findings using in vitro kinase and binding assays to explore selectivity within the Src- kinase family and possible synergy with ATP-site inhibitors. The anti-AML mechanism of action of the compounds will be tested in AML cell line models by correlating their effects on kinase activity and downstream substrate activation with growth suppression and apoptosis. Finally, we will determine the binding site for these putative allosteric inhibitors within Hck by X-ray crystallography. These experiments will provide crucial insight for the future development of these novel compounds as a treatment for AML, either as stand-alone therapy or in combination with existing ATP-site inhibitors. 1