Chromosome translocations involving mixed lineage leukemia (MLL) gene cause acute leukemia with a poor prognosis. MLL is frequently fused with transcription cofactors AF4 (~35%), AF9 (25%) or its paralog ENL (10%). The AHD domain of AF9/ENL binds to AF4, its paralog AFF4, or histone-H3 lysine-79 (H3K79) methyltransferase DOT1L. Formation of AF9/ENL/AF4/AFF4-containing super elongation complexes (SEC) and the catalytic activity of DOT1L are essential for MLL-rearranged leukemia. Protein-protein interactions (PPI) between AF9/ENL and DOT1L/AF4/AFF4 are therefore a potential drug target./nMethods: Compound screening followed by medicinal chemistry was used to find inhibitors of such PPIs, which were examined for their biological activities against MLL-rearranged leukemia and other cancer cells./nResults: Compound-1 was identified to be a novel small-molecule inhibitor of the AF9/ENL-DOT1L/AF4/AFF4 interaction with IC50s of 0.9-3.5 µM. Pharmacological inhibition of the PPIs significantly reduced SEC and DOT1L-mediated H3K79 methylation in the leukemia cells. Gene profiling shows compound-1 significantly suppressed the gene signatures related to onco-MLL, DOT1L, HoxA9 and Myc. It selectively inhibited proliferation of onco-MLL- or Myc-driven cancer cells and induced cell differentiation and apoptosis. Compound-1 exhibited strong antitumor activity in a mouse model of MLL-rearranged leukemia./nConclusions: The AF9/ENL-DOT1L/AF4/AFF4 interactions are validated to be an anticancer target and compound-1 is a useful in vivo probe for biological studies as well as a pharmacological lead for further drug development.

中文翻译：

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AF9/ENL-DOT1L/AF4/AFF4 相互作用的小分子抑制剂抑制恶性基因表达和肿瘤生长

涉及混合谱系白血病（MLL）基因的染色体易位导致急性白血病，预后不良。MLL 经常与转录辅助因子 AF4 (~35%)、AF9 (25%) 或其旁系同源 ENL (10%) 融合。AF9/ENL 的 AHD 结构域与 AF4、其旁系同源物 AFF4 或组蛋白-H3 赖氨酸-79 (H3K79) 甲基转移酶 DOT1L 结合。含有 AF9/ENL/AF4/AFF4 的超延伸复合物 (SEC) 的形成和 DOT1L 的催化活性对于 MLL 重排白血病至关重要。因此，AF9/ENL 和 DOT1L/AF4/AFF4 之间的蛋白质-蛋白质相互作用 (PPI) 是潜在的药物靶点。/n方法：化合物筛选和药物化学用于寻找此类 PPI 的抑制剂，并检查其生物活性抗 MLL 重排白血病和其他癌细胞。/n结果：化合物-1被确定为一种新型的 AF9/ENL-DOT1L/AF4/AFF4 相互作用的小分子抑制剂，IC50 为 0.9-3.5 µM。PPI 的药理学抑制显着降低了白血病细胞中 SEC 和 DOT1L 介导的 H3K79 甲基化。基因分析显示化合物1显着抑制了与 onco-MLL、DOT1L、HoxA9 和 Myc 相关的基因特征。它选择性地抑制 onco-MLL 或 Myc 驱动的癌细胞的增殖并诱导细胞分化和凋亡。化合物- 1在 MLL 重排白血病小鼠模型中表现出很强的抗肿瘤活性。/n结论： AF9/ENL-DOT1L/AF4/AFF4 相互作用被证实是抗癌靶点，化合物- 1 是用于生物学研究的有用的体内探针，也是进一步药物开发的药理学先导。