Jerome Lipper Multiple Myeloma Center, Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts.
Department of Hematology, Saitama Medical Center, Saitama Medical University, Kawagoe, Saitama, Japan.
Clin Cancer Res. 2017 Sep 1;23(17):5225-5237. doi: 10.1158/1078-0432.CCR-17-0263. Epub 2017 Apr 25.
To investigate the biological and clinical significance of ribonucleotide reductase (RR) in multiple myeloma. We assessed the impact of RR expression on patient outcome in multiple myeloma. We then characterized the effect of genetic and pharmacologic inhibition of ribonucleotide reductase catalytic subunit M1 (RRM1) on multiple myeloma growth and survival using siRNA and clofarabine, respectively, in both and mouse xenograft models. Newly diagnosed multiple myeloma patients with higher RRM1 expression have shortened survival. Knockdown of RRM1 triggered significant growth inhibition and apoptosis in multiple myeloma cells, even in the context of the bone marrow microenvironment. Gene expression profiling showed upregulation of DNA damage response genes and p53-regulated genes after RRM1 knockdown. Immunoblot and qRT-PCR analysis confirmed that γ-H2A.X, ATM, ATR, Chk1, Chk2, RAD51, 53BP1, BRCA1, and BRCA2 were upregulated/activated. Moreover, immunoblots showed that p53, p21, Noxa, and Puma were activated in p53 wild-type multiple myeloma cells. Clofarabine, a purine nucleoside analogue that inhibits RRM1, induced growth arrest and apoptosis in p53 wild-type cell lines. Although clofarabine did not induce cell death in p53-mutant cells, it did trigger synergistic toxicity in combination with DNA-damaging agent melphalan. Finally, we demonstrated that tumor growth of RRM1-knockdown multiple myeloma cells was significantly reduced in a murine human multiple myeloma cell xenograft model. Our results therefore demonstrate that RRM1 is a novel therapeutic target in multiple myeloma in the preclinical setting and provide the basis for clinical evaluation of RRM1 inhibitor, alone or in combination with DNA-damaging agents, to improve patient outcome in multiple myeloma. .
为了研究核糖核苷酸还原酶（RR）在多发性骨髓瘤中的生物学和临床意义。我们评估了 RR 表达对多发性骨髓瘤患者预后的影响。然后，我们使用 siRNA 和氯法拉滨分别在 和 小鼠异种移植模型中，对核糖核苷酸还原酶催化亚基 M1（RRM1）的遗传和药物抑制对多发性骨髓瘤生长和存活的影响进行了表征。RRM1 表达较高的新诊断多发性骨髓瘤患者的生存时间缩短。RRM1 敲低可导致多发性骨髓瘤细胞明显的生长抑制和凋亡，即使在骨髓微环境中也是如此。基因表达谱分析显示 RRM1 敲低后 DNA 损伤反应基因和 p53 调控基因上调。免疫印迹和 qRT-PCR 分析证实 RRM1 敲低后 γ-H2A.X、ATM、ATR、Chk1、Chk2、RAD51、53BP1、BRCA1 和 BRCA2 被上调/激活。此外，免疫印迹显示 p53 野生型多发性骨髓瘤细胞中 p53、p21、Noxa 和 Puma 被激活。氯法拉滨是一种抑制 RRM1 的嘌呤核苷类似物，可诱导 p53 野生型细胞系生长停滞和凋亡。虽然氯法拉滨不能诱导 p53 突变细胞死亡，但它与 DNA 损伤药物美法仑联合使用时会引发协同毒性。最后，我们证明了在小鼠人多发性骨髓瘤细胞异种移植模型中，RRM1 敲低多发性骨髓瘤细胞的肿瘤生长明显减少。我们的结果因此表明，RRM1 是一种新的多发性骨髓瘤治疗靶点，为临床评估 RRM1 抑制剂单独或与 DNA 损伤剂联合使用，以改善多发性骨髓瘤患者的预后提供了依据。
