Division of Life Sciences, College of Life Sciences and Biotechnology, Korea University, Seoul, 02841, Republic of Korea.
Department of Hematology, Chonnam National University Hwasun Hospital, Hwasun, 58128, Republic of Korea.
Int J Cancer. 2017 May 15;140(10):2364-2374. doi: 10.1002/ijc.30662. Epub 2017 Mar 9.
Treatment of acute myeloid leukemia (AML) largely depends on chemotherapy, but current regimens have been unsatisfactory for long-term remission. Although differentiation induction therapy utilizing 1,25(OH) D (VD3) has shown great promise for the improvement of AML treatment efficacy, severe side effects caused by its supraphysiological dose limit its clinical application. Here we investigated the combinatorial effect of l-asparaginase (ASNase)-mediated amino acid depletion and the latent alternation of VD3 activity on the induction of myeloid differentiation. ASNase treatment enhanced VD3-driven phenotypic and functional differentiation of three-different AML cell lines into monocyte/macrophages, along with c-Myc downregulation. Using gene silencing with shRNA and a chemical blocker, we found that reduced c-Myc is a critical factor for improving VD3 efficacy. c-Myc-dependent inhibition of mTORC1 signaling and induction of autophagy were involved in the enhanced AML cell differentiation. In addition, in a postculture of AML cells after each treatment, ASNase supports the antileukemic effect of VD3 by inhibiting cell growth and inducing apoptosis. Finally, we confirmed that the administration of ASNase significantly improved VD3 efficacy in the prolongation of survival time in mice bearing tumor xenograft. Our results are the first to demonstrate the extended application of ASNase, which is currently used for acute lymphoid leukemia, in VD3-mediated differentiation induction therapy for AML, and suggest that this drug combination may be a promising novel strategy for curing AML.
急性髓细胞白血病(AML)的治疗在很大程度上依赖于化疗,但目前的方案并不能长期缓解。虽然利用 1,25(OH)2D3(VD3)进行分化诱导治疗显示出提高 AML 治疗效果的巨大潜力,但由于其超生理剂量引起的严重副作用,限制了其临床应用。在这里,我们研究了 L-天冬酰胺酶(ASNase)介导的氨基酸耗竭与 VD3 活性的潜在改变联合作用对髓样分化的诱导作用。ASNase 治疗增强了三种不同 AML 细胞系向单核细胞/巨噬细胞的 VD3 驱动的表型和功能分化,同时下调了 c-Myc。通过 shRNA 和化学抑制剂的基因沉默,我们发现降低 c-Myc 是提高 VD3 疗效的关键因素。c-Myc 依赖性抑制 mTORC1 信号和诱导自噬参与了增强的 AML 细胞分化。此外,在每种处理后 AML 细胞的培养后,ASNase 通过抑制细胞生长和诱导细胞凋亡来支持 VD3 的抗白血病作用。最后,我们证实 ASNase 的给药显著提高了 VD3 在延长荷瘤小鼠生存时间方面的疗效。我们的研究结果首次证明了目前用于急性淋巴细胞白血病的 ASNase 在 VD3 介导的 AML 分化诱导治疗中的扩展应用,并表明这种药物联合可能是治疗 AML 的一种很有前途的新策略。
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