Abstract：
Acute myeloid leukaemia (AML) is one of the most common types of haematopoietic malignancy. Ribonucleotide reductase (RNR) is a key enzyme required for DNA synthesis and cell proliferation, and its small subunit RRM2 plays a key role for the enzymatic activity. We predicted monobenzone (MB) as a potential RRM2 target compound based on the crystal structure of RRM2. In vitro, MB inhibited recombinant RNR activity (IC50 = 0.25 μM). Microscale thermophoresis indicated that MB inhibited RNR activity by binding to RRM2. MB inhibited cell proliferation (MTT IC50 = 6-18 μM) and caused dose-dependent DNA synthesis inhibition, cell cycle arrest, and apoptosis in AML cells. The cell cycle arrest was reversed by the addition of deoxyribonucleoside triphosphates precursors, suggesting that RNR was the intracellular target of the compound. Moreover, MB overcame drug resistance to the common AML drugs cytarabine and doxorubicin, and treatment with the combination of MB and the Bcl-2 inhibitor ABT-737 exerted a synergistic inhibitory effect. Finally, the nude mice xenografts study indicated that MB administration produced a significant inhibitory effect on AML growth with relatively weak toxicity. Thus, we propose that MB has the potential as a novel anti-AML therapeutic agent in the future.
摘要：
急性髓性白血病（AML）是最常见的造血系统恶性肿瘤之一。核糖核苷酸还原酶（RNR）是DNA合成和细胞增殖所需的关键酶，它的小亚基RRM2对酶活性起着关键作用。根据RRM2的晶体结构，我们预测了单苯宗（MB）作为潜在的RRM2目标化合物。体外，MB抑制重组RNR活性(IC50=0.25μM)。微尺度热电泳表明MB通过与RRM2结合抑制RNR活性。MB抑制细胞增殖（MTTIC50=6-18μM），并引起剂量依赖性DNA合成抑制，细胞周期停滞,AML细胞凋亡。通过添加脱氧核糖核苷三磷酸前体逆转了细胞周期停滞，表明RNR是该化合物的细胞内靶标。此外，MB克服了对常见AML药物阿糖胞苷和阿霉素的耐药性，并且用MB和Bcl-2抑制剂ABT-737的组合治疗发挥协同抑制作用。最后,裸鼠异种移植研究表明,MB给药对AML生长产生显著的抑制作用,毒性相对较弱.因此，我们认为MB在未来具有作为新型抗AML治疗剂的潜力.
