Assay Development for NSD1 Methyltransferase Inhibitor Discovery

一个突出的例子是由NUP 98（核孔蛋白，核孔复合物的98-kd组分）和NSD 1（核受体结合SET结构域蛋白1）基因重排引起的特别侵袭性类型的急性髓性白血病（AML）。这种重排导致通常分离的NUP 98和NSD 1蛋白的融合。第一个NUP 98-NSD 1融合体是在不到15年前发现的，此后很明显，这些遗传病变经常被AML患者的常规基因检测所遗漏。最近使用特定检测方法的综合研究发现，携带NUP 98-NSD 1的AML存在于4-5%的儿科AML中，与10- 30%的严峻的4年无事件生存率相关。因此，迫切需要专门针对这组儿科患者的新疗法。携带NUP 98-NSD 1融合体的AML是通过激活特定致癌癌基因的表达而引发的，这导致细胞分化的正常过程无法产生特定类型的血细胞。未分化的细胞获得了不受抑制的增殖能力，正是这种获得的“自我更新”能力是这些儿童白血病病例的关键触发因素。NSD 1是一种甲基转移酶，通过甲基化组蛋白中的特定赖氨酸残基来激活基因表达，从而影响组蛋白与DNA的相互作用。因此，抑制NSD 1的酶活性的小分子应该能有效逆转导致AML的特定基因的激活，并允许恶性细胞恢复到正常的分化形式。我们的目标是开发一套检测方法，以高通量筛选数十万种化合物，发现NSD 1酶的抑制剂，并表征这些抑制剂，以确定选择性化学探针和领先的候选分子疗法，靶向具有NUP 98-NSD 1融合的儿童白血病。

DESCRIPTION (provided by applicant): Despite dramatic treatment advances in the past few decades, there remain subsets of pediatric leukemia that are very difficult to treat. A striking example is a particularly aggressive type of acute myeloid leukemia (AML) caused by rearrangement of the genes NUP98 (nucleoporin, 98-kd component of nuclear pore complex) and NSD1 (nuclear receptor-binding SET domain protein 1). This rearrangement leads to fusion of the normally separate NUP98 and NSD1 proteins. The first NUP98-NSD1 fusion was identified less than fifteen years ago, and it has since become clear that these genetic lesions are often missed by routine genetic testing of AML patients. Recent comprehensive studies using a specific detection method found that AML harboring NUP98- NSD1 was present in 4-5% of pediatric AML, associated with a grim 4-year event-free survival rate of 10-30%. Thus novel therapies specifically targeted to this group of pediatric patients are urgently needed. AML harboring NUP98-NSD1 fusions is initiated through activation of the expression of specific cancer-causing oncogenes, which results in a failure of the normal process of cell differentiation to give specific types of blood cell. Undifferentiated cells acquire the ability to proliferate unchecked, and it is this acquired capacity for "self- renewal" that is the key trigger for these cases of pediatric leukemia. NSD1 is a methyltransferase enzyme that activates gene expression by methylating a specific lysine residue in histones, affecting their interaction with DNA. Therefore, small molecules that inhibit the enzyme activity of NSD1 should be effective in reversing activation of the specific genes causing AML and allow malignant cells to revert to a normal differentiated form. Our goal is to develop a suite of assays to enable high-throughput screening of several hundred thousand compounds to discover inhibitors of the NSD1 enzyme, and to characterize these inhibitors to identify selective chemical probes and lead candidates as molecular therapies targeted to childhood leukemia's harboring the NUP98-NSD1 fusion.