Khong Tiffany, Sharkey Janelle, Spencer Andrew
Myeloma Research Group, Department of Clinical Haematology and Bone Marrow Transplantation, Alfred Hospital, Melbourne, Victoria, Australia.
Haematologica. 2008 Jun;93(6):860-9. doi: 10.3324/haematol.12261. Epub 2008 Apr 28.
Azacitidine is a DNA methyltransferase inhibitor and cytotoxic agent known to induce apoptosis of some cancer cells. This study evaluated the pre-clinical potential of azacitidine as a therapeutic agent for multiple myeloma.
Dose responsiveness to azacitidine was determined utilizing a panel of genetically heterogenous human multiple myeloma cell lines. Azacitidine was also tested against primary multiple myeloma cells and in the 5T33MM murine model of systemic myelomatosis. Mechanistic studies included immunoblotting of key apoptosis signaling proteins, analysis of p16 gene methylation status, and characterization of both the interleukin-6 and nuclear factor-kappaB signaling pathways following azacitidine treatment.
Human myeloma cell lines and primary multiple myeloma cells underwent apoptosis following exposure to clinically achievable concentrations of azacitidine (1 microM-20 microM). Similarly, azacitidine prolonged survival from 24.5 days to 32 days (p=0.001, log rank) in the 5T33MM model. At a mechanistic level azacitidine down-regulated two crucial cell survival pathways in multiple myeloma. First, it inhibited the elaboration of both interleukin-6 receptor-alpha and interleukin- 6 resulting in the reduced expression of both phospho-STAT3 and Bcl-xl. Secondly, azacitidine inhibited both nuclear factor-kappaB nuclear translocation and DNA binding in a manner independent of IkappaB. The kinetics of these azacitidine-induced responses was more consistent with protein synthesis inhibition than with either hypomethylation or another DNA-mediated effect.
Azacitidine rapidly induces apoptosis of multiple myeloma cells, is effective in vivo against multiple myeloma and inhibits two crucial cell survival pathways in this disease. We conclude that azacitidine demonstrates novel and highly relevant anti-myeloma effects and warrants further evaluation in a clinical context.
阿扎胞苷是一种DNA甲基转移酶抑制剂和细胞毒性药物，已知可诱导某些癌细胞凋亡。本研究评估了阿扎胞苷作为多发性骨髓瘤治疗药物的临床前潜力。
利用一组基因异质性的人类多发性骨髓瘤细胞系确定对阿扎胞苷的剂量反应性。阿扎胞苷还在原发性多发性骨髓瘤细胞和系统性骨髓瘤病的5T33MM小鼠模型中进行了测试。机制研究包括关键凋亡信号蛋白的免疫印迹、p16基因甲基化状态分析以及阿扎胞苷处理后白细胞介素-6和核因子-κB信号通路的特征描述。
人类骨髓瘤细胞系和原发性多发性骨髓瘤细胞在暴露于临床可达到的阿扎胞苷浓度（1微摩尔/升 - 20微摩尔/升）后发生凋亡。同样，在5T33MM模型中，阿扎胞苷将生存期从24.5天延长至32天（p = 0.001，对数秩检验）。在机制层面，阿扎胞苷下调了多发性骨髓瘤中两条关键的细胞存活途径。首先，它抑制白细胞介素-6受体-α和白细胞介素-6的生成，导致磷酸化STAT3和Bcl-xl的表达降低。其次，阿扎胞苷以独立于IκB的方式抑制核因子-κB的核转位和DNA结合。这些阿扎胞苷诱导反应的动力学与蛋白质合成抑制比与低甲基化或其他DNA介导的效应更一致。
阿扎胞苷可迅速诱导多发性骨髓瘤细胞凋亡，在体内对多发性骨髓瘤有效，并抑制该疾病中两条关键的细胞存活途径。我们得出结论，阿扎胞苷显示出新颖且高度相关的抗骨髓瘤作用，值得在临床环境中进一步评估。
