The BCL2-inhibitor, Venetoclax (VEN), has shown significant anti-leukemic efficacy in combination with the DNMT-inhibitor, Azacytidine (AZA). To explore the mechanisms underlying the selective sensitivity of mutant leukemia cells to VEN and AZA, we used cell-based isogenic models containing a common leukemia-associated mutation in the epigenetic regulator ASXL1. KBM5 cells with CRISPR/Cas9-mediated correction of the ASXL1^G710X mutation showed reduced leukemic growth, increased myeloid differentiation, and decreased HOXA and BCL2 gene expression in vitro compared to uncorrected KBM5 cells. Increased expression of the anti-apoptotic gene, BCL2, was also observed in bone marrow CD34+ cells from ASXL1 mutant MDS patients compared to CD34+ cells from wild-type MDS cases. ATAC-sequencing demonstrated open chromatin at the BCL2 promoter in the ASXL1 mutant KBM5 cells. BH3 profiling demonstrated increased dependence of mutant cells on BCL2. Upon treatment with VEN, mutant cells demonstrated increased growth inhibition. In addition, genome-wide methylome analysis of primary MDS samples and isogenic cell lines demonstrated increased gene-body methylation in ASXL1 mutant cells, with consequently increased sensitivity to AZA. These data mechanistically link the common leukemia-associated mutation ASXL1 to enhanced sensitivity to VEN and AZA via epigenetic upregulation of BCL2 expression and widespread alterations in DNA methylation.

BCL2 抑制剂 Venetoclax (VEN) 与 DNMT 抑制剂阿扎胞苷 (AZA) 联合使用已显示出显着的抗白血病功效。为了探索突变白血病细胞对 VEN 和 AZA 选择性敏感性的潜在机制，我们使用了基于细胞的同基因模型，该模型在表观遗传调节因子ASXL1中包含常见的白血病相关突变。与未校正的 KBM5 细胞相比，具有 CRISPR/Cas9 介导的ASXL1 ^G710X突变校正的 KBM5 细胞在体外显示出白血病生长减少、骨髓分化增加以及HOXA和BCL2基因表达降低。在骨髓 CD34+ 细胞中也观察到抗凋亡基因BCL2的表达增加。ASXL1突变 MDS 患者与来自野生型 MDS 病例的 CD34+ 细胞相比。ATAC 测序显示ASXL1 突变体 KBM5 细胞中BCL2启动子的染色质开放。BH3 分析表明突变细胞对BCL2的依赖性增加。在用 VEN 处理后，突变细胞表现出增加的生长抑制。此外，原代 MDS 样品和同基因细胞系的全基因组甲基化组分析表明，ASXL1突变细胞中基因体甲基化增加，因此对 AZA 的敏感性增加。这些数据通过BCL2的表观遗传上调将常见的白血病相关突变ASXL1与增强对 VEN 和 AZA 的敏感性联系起来DNA甲基化的表达和广泛改变。