A hallmark of acute myeloid leukaemias (AMLs) are chromosomal rearrangements that give rise to novel leukaemia-specific fusion genes. Most of these fusion genes are both initiating and driving events in AML and therefore constitute ideal therapeutic targets but are challenging to target by conventional drug development. siRNAs are frequently used for the specific suppression of fusion gene expression but require special formulations for efficient in vivo delivery. Here we describe the use of siRNA-loaded lipid nanoparticles for the specific therapeutic targeting of the leukaemic fusion gene RUNX1/ETO. Transient knockdown of RUNX1/ETO reduces its binding to its target genes and alters the binding of RUNX1 and its co-factor CBFB;. Transcriptomic changes in vivo were associated with substantially increased median survival of a t(8;21)-AML mouse model. Importantly, transient knockdown in vivo causes long-lasting inhibition of leukaemic proliferation and clonogenicity, induction of myeloid differentiation and a markedly impaired re-engraftment potential in vivo. These data strongly suggest that temporary inhibition of RUNX1/ETO results in long-term restriction of leukaemic self-renewal. Our results provide proof for the feasibility of targeting RUNX1/ETO in a pre-clinical setting and support the further development of siRNA-LNPs for the treatment of fusion gene-driven malignancies.

中文翻译：

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纳米颗粒介导的融合基因 RUNX1/ETO 在 t(8;21) 阳性急性髓系白血病中的靶向作用

急性髓性白血病 (AML) 的一个标志是染色体重排，可产生新的白血病特异性融合基因。大多数这些融合基因在 AML 中既是启动事件又是驱动事件，因此构成理想的治疗靶点，但对常规药物开发的靶向具有挑战性。siRNA 经常用于特异性抑制融合基因的表达，但需要特殊的配方才能有效地进行体内递送。在这里，我们描述了使用负载 siRNA 的脂质纳米颗粒对白血病融合基因 RUNX1/ETO 进行特异性治疗。RUNX1/ETO 的瞬时敲低降低了其与其靶基因的结合并改变了 RUNX1 及其辅因子 CBFB 的结合；体内转录组变化与 at(8;21)-AML 小鼠模型的中位生存期显着增加有关。重要的是，体内瞬时敲低导致白血病增殖和克隆形成的长期抑制、骨髓分化的诱导和体内再移植潜力的显着受损。这些数据强烈表明 RUNX1/ETO 的暂时抑制会导致白血病自我更新的长期限制。我们的结果为在临床前环境中靶向 RUNX1/ETO 的可行性提供了证据，并支持进一步开发 siRNA-LNP 以治疗融合基因驱动的恶性肿瘤。这些数据强烈表明 RUNX1/ETO 的暂时抑制会导致白血病自我更新的长期限制。我们的结果为在临床前环境中靶向 RUNX1/ETO 的可行性提供了证据，并支持进一步开发 siRNA-LNP 以治疗融合基因驱动的恶性肿瘤。这些数据强烈表明 RUNX1/ETO 的暂时抑制会导致白血病自我更新的长期限制。我们的结果为在临床前环境中靶向 RUNX1/ETO 的可行性提供了证据，并支持进一步开发 siRNA-LNP 以治疗融合基因驱动的恶性肿瘤。