Taylor Jordan S, Zeki Jasmine, Ornell Kimberly, Coburn Jeannine, Shimada Hiroyuki, Ikegaki Naohiko, Chiu Bill
Department of Surgery, Stanford University, Stanford, CA.
Department of Biomedical Engineering, Worcester Polytechnic Institute, Worcester, MA.
J Pediatr Surg. 2019 Jun;54(6):1192-1197. doi: 10.1016/j.jpedsurg.2019.02.028. Epub 2019 Feb 28.
MYCN oncogene amplification is an independent predictor of poor prognosis in neuroblastoma. CX-5461 is a small molecular inhibitor that prevents initiation of ribosomal RNA (rRNA) synthesis by RNA Pol I, down-regulating MYCN/MYC proteins. We hypothesize that neuroblastoma tumor growth can be suppressed by CX-5461.
MYCN-amplified (KELLY, IMR5) and nonamplified (SY5Y, SKNAS) neuroblastoma cells were treated with CX-5461. MYCN/MYC expression after 24-48 h was determined by Western blot. Orthotopic neuroblastoma tumors created in mice using KELLY cells were treated with CX-5461-loaded silk films implanted locally. Tumor growth was monitored using ultrasound. Histologic evaluation of tumors was performed.
IC for KELLY, IMR5, SY5Y, and SKNAS cells to CX-5461 was 0.75 μM, 0.02 μM, 0.8 μM, and 1.7 μM, respectively. CX-5461 down-regulated MYCN and MYC proteins at 0.25-1.0 μM on Western blot analysis. CX-5461-loaded silk film released 23.7±3 μg of the drug in 24 h and 48.2±3.9 μg at 120 h. KELLY tumors treated with CX-5461-loaded film reached 800 mm after 7.8±1.4 days, while those treated with control film reached the same size on 5.1±0.6 days (p=0.03). CX-5461-treated tumors showed collapse of nucleolar hypertrophy and MYCN protein downregulation.
We demonstrated that local delivery of CX-5461 via sustained release platform can suppress orthotopic neuroblastoma tumor growth, especially those with MYCN/MYC overexpression.
MYCN癌基因扩增是神经母细胞瘤预后不良的独立预测指标。CX - 5461是一种小分子抑制剂，可通过RNA聚合酶I阻止核糖体RNA（rRNA）合成的起始，下调MYCN/MYC蛋白。我们假设CX - 5461可抑制神经母细胞瘤肿瘤生长。
用CX - 5461处理MYCN扩增的（KELLY、IMR5）和未扩增的（SY5Y、SKNAS）神经母细胞瘤细胞。24 - 48小时后通过蛋白质印迹法测定MYCN/MYC表达。使用KELLY细胞在小鼠体内创建原位神经母细胞瘤肿瘤，用局部植入载有CX - 5461的丝膜进行治疗。使用超声监测肿瘤生长。对肿瘤进行组织学评估。
KELLY、IMR5、SY5Y和SKNAS细胞对CX - 5461的半数抑制浓度（IC）分别为0.75 μM、0.02 μM、0.8 μM和1.7 μM。蛋白质印迹分析显示，CX - 5461在0.25 - 1.0 μM时下调MYCN和MYC蛋白。载有CX - 5461的丝膜在24小时内释放23.7±3 μg药物，在120小时时释放48.2±3.9 μg。用载有CX - 5461的丝膜治疗的KELLY肿瘤在7.8±1.4天后达到800 mm³，而用对照丝膜治疗的肿瘤在5.1±0.6天达到相同大小（p = 0.03）。经CX - 5461治疗的肿瘤显示核仁肥大消失且MYCN蛋白下调。
我们证明，通过缓释平台局部递送CX - 5461可抑制原位神经母细胞瘤肿瘤生长，尤其是那些MYCN/MYC过表达的肿瘤。
