Translation initiation as a therapeutic target in neuroblastoma

项目总结/摘要 神经母细胞瘤（NB）是小儿交感神经系统的实体瘤，占15% 儿童癌症死亡率。在一半的患者中观察到MYCN转录因子的肿瘤细胞扩增 与高风险疾病，在那里它作为一个致癌驱动程序与转移性疾病和穷人 生存扩增的MYCN作为细胞生长的调节剂，通过刺激基因的表达， 在核糖体生物发生和蛋白质翻译的调节元件中的功能。我们已经确定了 翻译起始因子eIF 4A，一种RNA解旋酶，负责克服5′端翻译的障碍， 非翻译区（UTR）是转录特异性mRNA募集的主要调节因子， MYCN过表达NB细胞。eIF 4A是rocaglate类蛋白质合成的主要靶标 抑制剂，其通过将eIF 4A夹在 富含多聚嘌呤（PP-rich）的5′ UTR和阻止核糖体扫描。这种独特的作用方式提供了 - 对高度增殖性癌细胞的选择性，其中促存活转录物优先富集在PP中， 富有的领导者MYCN相关转录物在富含PP的5′ UTR序列中排名很高，其中大多数 在细胞增殖中起关键作用。从脒基-罗卡酸酯（ADR）的文库筛选， 由共同研究者，波士顿大学的John Porco博士开发的罗卡酸类似物，我们发现了一种 有希望的候选物，CMLD 012824，其破坏eIF 4A活性，从而抑制翻译并诱导 MYCN扩增的NB细胞中的选择性、剂量依赖性细胞毒性。我们假设ADR介导的 抑制eIF 4A将在MYCN扩增的NB细胞中诱导稳健的和选择性的细胞毒性， 将被证明是治疗这种侵袭性癌症的有效策略。在目标1中，我们将开发 有效的，高选择性的ADR和较新的胍基罗卡酸盐（GDR），对MYCN- 扩增的NB细胞，并表现出能够进行体内功效研究的药理学性质。在目标2中， 将研究ADR/GDR抑制在MYCN扩增的NB细胞系和肿瘤模型中的作用。的 这些研究的结果将为这类新的翻译抑制剂提供临床前验证， 治疗MYCN扩增的NB患者，并推动其向临床应用发展。我们 这些发现也可能与其他依赖于转录成瘾和非经典的癌症有关。 翻译起始机制，从而拓宽了这种治疗策略的范围。

PROJECT SUMMARY/ABSTRACT Neuroblastoma (NB) is a pediatric solid tumor of the sympathetic nervous system that accounts for 15% of childhood cancer deaths. Tumor cell amplification of the MYCN transcription factor is seen in half of patients with high-risk disease, where it functions as an oncogenic driver associated with metastatic disease and poor survival. Amplified MYCN functions as a regulator of cell growth by stimulating the expression of genes that function in ribosome biogenesis and regulatory elements of protein translation. We have identified the translation initiation factor eIF4A, an RNA-helicase responsible for overcoming blocks to translation of 5′ untranslated regions (UTRs) to be the predominant regulator of transcript-specific mRNA recruitment in MYCN-overexpressing NB cells. eIF4A is the primary target of the rocaglate class of protein synthesis inhibitors, which inhibit translation initiation in a transcript-specific manner by clamping eIF4A onto polypurine-rich (PP-rich) 5′ UTRs and preventing ribosome scanning. This unique mode of action provides selectivity for highly proliferative cancer cells in which pro-survival transcripts are preferentially enriched in PP- rich leaders. MYCN-associated transcripts rank highly in PP-rich 5′ UTR sequences, the majority of which have critical roles in cell proliferation. From a library screen of amidino-rocaglates (ADRs), novel synthetic rocaglate analogs developed by co-Investigator, Dr John Porco at Boston University, we identified a promising candidate, CMLD012824 that disrupts eIF4A activity, thereby inhibiting translation and inducing selective, dose-dependent cytotoxicity in MYCN-amplified NB cells. We hypothesize that ADR-mediated inhibition of eIF4A would induce robust and selective cytotoxicity in MYCN-amplified NB cells and would prove to be a valid therapeutic strategy in this aggressive cancer. In Aim 1, we will develop potent, highly selective ADRs and newer guanidino-rocaglates (GDRs) that have activity against MYCN- amplified NB cells and exhibit pharmacological properties that enable in vivo efficacy studies. In Aim 2, we will investigate the effects of ADR/GDR inhibition in MYCN-amplified NB cell line and tumor models. The results of these studies will provide preclinical validation of this new class of translation inhibitors for the treatment of MYCN-amplified NB patients, and propel their development towards clinical application. Our findings may also be relevant to other cancers that rely on transcriptional addiction and non-canonical translation initiation mechanisms, thereby broadening the scope of this therapeutic strategy.