Preclinical efficacy of targeting epigenetic mechanisms in AML with 3q26 lesions and EVI1 overexpression [RNA-Seq]

AML with chromosomal alterations involving 3q26 overexpress the transcription factor (TF) EVI1, associated with therapy refractoriness and inferior overall survival in AML. Consistent with a CRISPR screen highlighting BRD4 dependency, treatment with BET inhibitor (BETi) repressed EVI1, LEF1, c-Myc, c-Myb, CDK4/6, and MCL1, and induced apoptosis of AML cells with 3q26 lesions. Tegavivint (TV, BC-2059), known to disrupt binding of nuclear ß-catenin and TCF7L2/LEF1 with TBL1, also inhibited co-localization of EVI1 with TBL1 and dose-dependently induced apoptosis in AML cell lines and patient-derived (PD) AML cells with 3q26.2 lesions. TV treatment repressed EVI1, attenuated enhancer activity at ERG, TCF7L2, GATA2 and MECOM loci, abolished interactions between MYC enhancers, repressing AML stemness while upregulating mRNA gene-sets of interferon/inflammatory response, TGF-ß signaling and apoptosis-regulation. Co-treatment with TV and BETi or venetoclax induced synergistic in vitro lethality and reduced AML burden, improving survival of NSG mice harboring xenografts of AML with 3q26.2 lesions. Overall design: Paired end RNA Seq of MECOM (EVI1) expressing AML treated with tegavivint for 16 hours.

携带涉及3q26染色体区域畸变的急性髓系白血病（Acute Myeloid Leukemia, AML）会过表达转录因子（transcription factor, TF）EVI1，该特征与AML的治疗难治性及不良总生存期密切相关。与CRISPR筛选（CRISPR screen）所揭示的BRD4依赖性一致，BET抑制剂（BET inhibitor, BETi）处理可抑制EVI1、LEF1、c-Myc、c-Myb、CDK4/6及MCL1的表达，并诱导携带3q26异常的AML细胞发生凋亡。特加维特（Tegavivint, TV, BC-2059）作为可破坏核β-连环蛋白与TCF7L2/LEF1同TBL1结合的化合物，同样能够抑制EVI1与TBL1的共定位，并在携带3q26.2异常的AML细胞系及患者来源（patient-derived, PD）AML细胞中以剂量依赖性方式诱导细胞凋亡。TV处理可下调EVI1的表达，减弱ERG、TCF7L2、GATA2及MECOM基因座的增强子活性，破坏MYC增强子之间的相互作用，同时抑制AML干细胞干性，并上调干扰素/炎症反应、转化生长因子β（TGF-β）信号通路及细胞凋亡调控相关的mRNA基因集。TV与BETi或维奈克拉（venetoclax）联合给药可诱导体外协同致死效应，并降低体内AML负荷，同时改善携带3q26.2 AML异种移植瘤的NSG小鼠的存活情况。整体实验设计：对表达MECOM（EVI1）的AML细胞进行16小时特加维特处理后，开展双端RNA测序（Paired end RNA Seq）。