Promising activity of BET protein inhibitors (BETis) is compromised by adaptive or innate resistance in AML. Here, modeling of BETi-persister/resistance (BETi-P/R) in human post-MPN secondary AML (sAML) cells demonstrated accessible and active chromatin in specific super-enhancers/enhancers, which was associated with increased levels of nuclear β-catenin, TCF7L2, JMJD6, and c-Myc in BETi-P/R sAML cells. Following BETi treatment, c-Myc levels were rapidly restored in BETi-P/R sAML cells. CRISPR/Cas9-mediated knockout of TCF7L2 or JMJD6 reversed BETi-P/R, whereas ectopic overexpression conferred BETi-P/R in sAML cells; confirming the mechanistic role of the β-catenin-TCF7L2-JMJD6-MYC axis in BETi-resistance. Patient-derived, post-MPN, CD34+ sAML blasts exhibiting relative resistance to BETi, as compared to sensitive sAML blasts, displayed higher mRNA and protein expressions of TCF7L2, JMJD6 and c-Myc, and following BETi washout exhibited rapid restoration of c-Myc and JMJD6. CRISPR/Cas9 knockout of TCF7L2 and JMJD6 depleted their levels, inducing loss of viability of the sAML blasts. Disruption of co-localization of nuclear β-catenin with TBL1 and TCF7L2 by the small molecule inhibitor BC2059 combined with depletion of BRD4 by BET-PROTAC reduced c-Myc levels and exerted synergistic lethality in BETi-P/R sAML cells. This combination also reduced leukemia burden and improved survival of mice engrafted with BETi-P/R sAML cells or with patient-derived AML blasts innately resistant to BETi. Therefore, multi-targeted disruption of β-catenin-TCF7L2-JMJD6-MYC axis overcomes adaptive and innate BETi-resistance, exhibiting pre-clinical efficacy against human post-MPN sAML cells.

中文翻译：

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靶向 β-catenin-TCF7L2-JMJD6-c-Myc 轴克服对 BET 抑制剂耐药性的机制基础和功效

BET 蛋白抑制剂 (BETis) 的有希望的活性受到 AML 中适应性或先天性耐药性的影响。在这里，人类 MPN 后继发性 AML (sAML) 细胞中 BETi 持久性/抗性 (BETi-P/R) 的建模证明了特定超级增强子/增强子中可接近和活跃的染色质，这与核 β- 水平增加有关BETi-P/R sAML 细胞中的连环蛋白、TCF7L2、JMJD6 和 c-Myc。BETi 处理后，BETi-P/R sAML 细胞中的 c-Myc 水平迅速恢复。CRISPR/Cas9 介导的 TCF7L2 或 JMJD6 敲除逆转了 BETi-P/R，而异位过表达在 sAML 细胞中赋予了 BETi-P/R；证实了 β-catenin-TCF7L2-JMJD6-MYC 轴在 BETi 抗性中的机械作用。与敏感的 sAML 原始细胞相比，患者来源的 MPN 后 CD34+ sAML 原始细胞对 BETi 表现出相对抗性，显示出更高的 TCF7L2、JMJD6 和 c-Myc mRNA 和蛋白质表达，并且在 BETi 洗脱后显示 c-Myc 和 JMJD6 的快速恢复。TCF7L2 和 JMJD6 的 CRISPR/Cas9 敲除耗尽了它们的水平，导致 sAML 母细胞丧失活力。小分子抑制剂 BC2059 破坏核 β-连环蛋白与 TBL1 和 TCF7L2 的共定位，结合 BET-PROTAC 消耗 BRD4，降低了 c-Myc 水平，并在 BETi-P/R sAML 细胞中发挥协同致死作用。这种组合还减少了白血病负担并提高了植入 BETi-P/R sAML 细胞或患者来源的 AML 原始细胞对 BETi 具有先天抗性的小鼠的存活率。因此，β-catenin-TCF7L2-JMJD6-MYC 轴的多靶点破坏克服了适应性和先天性 BETi 抗性，对人 MPN 后 sAML 细胞表现出临床前疗效。