Synthesis and biological evaluation of novel 2,4-diaminoquinazoline derivatives as SMN2 promoter activators for the potential treatment of spinal muscular atrophy
Synthesis and biological evaluation of novel 2,4-diaminoquinazoline derivatives as SMN2 promoter activators for the potential treatment of spinal muscular atrophy
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DOI：
10.1021/jm061475p
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发表时间：
2008-02-14
影响因子：
7.3
通讯作者：
Singh, Jasbir
中科院分区：
文献类型：
--
作者：
Thurmond, John;Butchbach, Matthew E. R.;Singh, Jasbir
近端脊髓性肌萎缩症（SMA）是一种常染色体隐性遗传疾病，其特征是由运动神经元存活基因（SMN 1）缺失和/或突变引起的脊髓运动神经元死亡。与SMN 1相邻的是可变数量的SMN 2基因拷贝。这两种基因本质上相差一个核苷酸，这导致SMN 2的大部分RNA转录物缺乏外显子7。虽然SMN 1和SMN 2编码相同的Smn蛋白氨基酸序列，但SMN 1的缺失和SMN 2的不正确剪接导致Smn蛋白水平不足以维持运动神经元的存活。我们的药物化学努力的治疗目标是确定SMN 2启动子的小分子激活剂，通过上调基因转录，将产生更大量的全长Smn蛋白。我们最初的药物化学工作探索了一系列基于C5取代苄基醚的2，4-二氨基喹唑啉衍生物，发现这些衍生物是SMN 2启动子的有效激活剂;然而，DHFR的抑制被证明是与ATP消耗相关的脱靶活性。我们使用结构指导的方法来克服DHFR抑制，同时保留SMN 2启动子激活。先导化合物11 a被鉴定为具有高效力（EC 50 = 4 nM）和SMN 2启动子的2.3倍诱导。化合物IIa具有所需的药物性质，包括对小鼠口服给药后优异的脑暴露和长的脑半衰期。哌啶化合物IIa在NSC-34细胞（一种小鼠运动神经元杂交细胞系）中上调小鼠SMN基因的表达。在I型SMA患者成纤维细胞中，当通过免疫印迹分析时，化合物IIa以剂量依赖性方式诱导Smn，并增加称为gems的核内颗粒的数量。该化合物将I型SMA患者成纤维细胞中的宝石数量恢复到接近未受影响的SMA遗传载体的水平。
Proximal spinal muscular atrophy (SMA) is an autosomal recessive disorder characterized by death of motor neurons in the spinal cord that is caused by deletion and/or mutation of the survival motor neuron gene (SMN1). Adjacent to SMN1 are a variable number of copies of the SMN2 gene. The two genes essentially differ by a single nucleotide, which causes the majority of the RNA transcripts from SMN2 to lack exon 7. Although both SMN1 and SMN2 encode the same Smn protein amino acid sequence, the loss of SMN1 and incorrect splicing of SMN2 have the consequence that Smn protein levels are insufficient for the survival of motor neurons. The therapeutic goal of our medicinal chemistry effort was to identify small-molecule activators of the SMN2 promoter that, by up-regulating gene transcription, would produce greater quantities of full-length Smn protein. Our initial medicinal chemistry effort explored a series of C5 substituted benzyl ether based 2,4-diaminoquinazoline derivatives that were found to be potent activators of the SMN2 promoter; however, inhibition of DHFR was shown to be an off-target activity that was linked to ATP depletion. We used a structure-guided approach to overcome DHFR inhibition while retaining SMN2 promoter activation. A lead compound 11a was identified as having high potency (EC50 = 4 nM) and 2.3-fold induction of the SMN2 promoter. Compound Ila possessed desirable pharmaceutical properties, including excellent brain exposure and long brain half-life following oral dosing to mice. The piperidine compound Ila up-regulated expression of the mouse SMN gene in NSC-34 cells, a mouse motor neuron hybrid cell line. In type I SMA patient fibroblasts, compound Ila induced Smn in a dose-dependent manner when analyzed by immuno-blotting and increased the number of intranuclear particles called gems. The compound restored gems numbers in type I SMA patient fibroblasts to levels near unaffected genetic carriers of SMA.