Bandino Andrea, Geerts Dirk, Koster Jan, Bachmann André S
Department of Pharmaceutical Sciences, The Daniel K. Inouye College of Pharmacy, University of Hawaii at Hilo, 34 Rainbow Drive, Hilo, HI, 96720, USA.
Cell Oncol (Dordr). 2014 Dec;37(6):387-98. doi: 10.1007/s13402-014-0201-9. Epub 2014 Oct 15.
Neuroblastoma (NB) is an aggressive pediatric malignancy that typically occurs in infants and children under the age of 5 years. High-stage tumors relapse frequently even after aggressive multimodal treatment, resulting in therapy resistance and eventually in patient death. Clearly, new biologically-targeted drugs are needed that more efficiently suppress tumor growth and prevent relapse. We and others previously showed that polyamines such as spermidine play an essential role in NB tumorigenesis and that DFMO, an inhibitor of the central polyamine synthesis gene ODC, is effective in vitro and in vivo, prompting its evaluation in NB clinical trials. However, the specific molecular actions of polyamines remain poorly defined. Spermidine and deoxyhypusine synthase (DHPS) are essential components in the hypusination-driven post-translational activation of eukaryotic initiation factor 5A (eIF5A).
We assessed the role of DHPS in NB and the impact of its inhibition by N(1)-guanyl-1,7-diaminoheptane (GC7) on tumor cell growth using cell proliferation assays, Western blot, immunofluorescence microscopy, and Affymetrix micro-array mRNA expression analyses in NB tumor samples.
We found that GC7 inhibits NB cell proliferation in a dose-dependent manner, through induction of the cell cycle inhibitor p21 and reduction of total and phosphorylated Rb proteins. Strikingly, high DHPS mRNA expression correlated significantly with unfavorable clinical parameters, including poor patient survival, in a cohort of 88 NB tumors (all P < 0.04).
These results suggest that spermidine and DHPS are key contributing factors in NB tumor proliferation through regulation of the p21/Rb signaling axis.
神经母细胞瘤（NB）是一种侵袭性儿科恶性肿瘤，通常发生于5岁以下的婴幼儿。即使经过积极的多模式治疗，高分期肿瘤仍频繁复发，导致治疗耐药并最终致使患者死亡。显然，需要新的生物靶向药物来更有效地抑制肿瘤生长并预防复发。我们和其他人之前表明，诸如亚精胺之类的多胺在NB肿瘤发生中起关键作用，并且二氟甲基鸟氨酸（DFMO），一种中心多胺合成基因鸟氨酸脱羧酶（ODC）的抑制剂，在体外和体内均有效，这促使其在NB临床试验中得到评估。然而，多胺的具体分子作用仍不清楚。亚精胺和脱氧hypusine合酶（DHPS）是真核起始因子5A（eIF5A）的hypusination驱动的翻译后激活中的关键成分。
我们使用细胞增殖试验、蛋白质免疫印迹、免疫荧光显微镜检查以及对NB肿瘤样本进行Affymetrix微阵列mRNA表达分析，评估了DHPS在NB中的作用及其被N(1)-鸟苷基-1,7-二氨基庚烷（GC7）抑制对肿瘤细胞生长的影响。
我们发现GC7以剂量依赖的方式抑制NB细胞增殖，通过诱导细胞周期抑制剂p21以及降低总Rb蛋白和磷酸化Rb蛋白水平。令人惊讶的是，在一组88例NB肿瘤中，高DHPS mRNA表达与不良临床参数显著相关，包括患者生存率低（所有P < 0.04）。
这些结果表明，亚精胺和DHPS通过调节p21/Rb信号轴是NB肿瘤增殖的关键促成因素。
