Targeted therapy for 11q23 acute leukemias

项目总结 染色体11q23处MLL基因重排预示患者预后不良 患有急性白血病。在5%-10%的急性白血病中发现MLL重排，并 尤其常见于白血病婴儿和化疗相关的继发性 白血病。治疗MLL白血病的新方法日益受到重视 积极的治疗只在存活率方面产生了适度的改善。 MLL基因座的相互易位是不同的，但最常见的两种 易位伙伴是AF4和AF9基因。我们之前证明了AF4和AF9 蛋白质形成多蛋白质复合体。此外，蛋白质复合体在体外和体内都可以被破坏。 通过模拟AF4的AF9结合部位的小的合成肽。当接触到这样的一种 表达MLL-AF4或MLL-AF9融合基因的白血病细胞株 细胞因坏死而发生程序性死亡。重要的是，对骨髓集落形成没有影响 观察到的多肽浓度对白血病细胞有毒性。 对这些观察结果的一种可能的解释是，大分子络合物包括 AF4和AF9嵌合蛋白对t(4；11)和t(9；11)白血病细胞的存活至关重要。通过 PFWT结合AF9并破坏MLL-AF4-AF9(或MLL-AF9-AF4)蛋白复合体抑制MLL 白血病。本研究的重点是AF4和AF4相互作用结构域的作用。 并将研究AF9与AF4或Dot1组蛋白甲基转移酶结合的要求 在白血病的发生中。 通过分析特定蛋白质对嵌合癌蛋白活性的贡献， 这些研究旨在揭示治疗MLL白血病的有前途的新方法。我们有 将PFWT肽设计为阻止蛋白质相互作用的分子原型，这些蛋白质相互作用对 白血病细胞存活率。然而，我们也希望将实验工具的影响扩大到可行 治疗策略。因此，PFWT多肽的高度取代和更有效的衍生物SPK- 107，将在人类MLL白血病的小鼠模型上进行测试。这些临床前研究是 旨在为药物开发奠定基础。

PROJECT SUMMARY Rearrangements of the MLL gene at chromosome 11q23 portend a poor prognosis in patients with acute leukemia. MLL rearrangements are found in 5-10% of acute leukemias and are particularly common both in babies with leukemia and in chemotherapy-associated secondary leukemia. New approaches to the treatment of MLL leukemia are warranted as increasingly aggressive therapy has yielded only modest improvements in survival. Reciprocal translocations at the MLL locus are heterogeneous, but the two most common translocation partners are the AF4 and AF9 genes. We previously demonstrated that AF4 and AF9 proteins form a multiprotein complex. Moreover, the protein complex can be disrupted in vitro and in vivo by small synthetic peptides that mimic the AF9 binding site of AF4. When exposed to one such peptide, designated PFWT, leukemia cell lines expressing MLL-AF4 or MLL-AF9 fusion genes undergo programmed cell death by necrosis. Importantly, no effect on bone marrow colony formation is observed at peptide concentrations that are toxic to leukemia cells. One possible explanation for these observations is that macromolecular complexes comprised of AF4 and AF9 chimeric proteins are crucial for the survival of t(4;11) and t(9;11) leukemia cells. By binding AF9 and disrupting MLL-AF4-AF9 (or MLL-AF9-AF4) protein complexes, PFWT inhibits MLL leukemias. This research project focuses on the role of the mutual interaction domains of AF4 and AF9 and will examine the requirement for binding of AF9 to AF4 or to Dot1 histone methyltransferase in leukemogenesis. By analyzing the contributions of specific proteins to the activity of chimeric oncoproteins, these studies are designed to reveal promising new approaches to treat MLL leukemia. We have devised the PFWT peptide as a prototype of molecules that block protein interactions critical to leukemia cell survival. However, we also hope to extend the impact of experimental tools to feasible treatment strategies. Thus, a highly substituted and more potent derivative of PFWT peptide, SPK- 107, will be tested in a mouse model of human MLL leukemia. These pre-clinical studies are intended to lay the groundwork for pharmaceutical drug development.