Department of Oncogenomics, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
Proc Natl Acad Sci U S A. 2012 Nov 20;109(47):19190-5. doi: 10.1073/pnas.1208215109. Epub 2012 Oct 22.
Neuroblastoma is a pediatric tumor of the sympathetic nervous system. MYCN (V-myc myelocytomatosis viral-related oncogene, neuroblastoma derived [avian]) is amplified in 20% of neuroblastomas, and these tumors carry a poor prognosis. However, tumors without MYCN amplification also may have a poor outcome. Here, we identified downstream targets of MYCN by shRNA-mediated silencing MYCN in neuroblastoma cells. From these targets, 157 genes showed an expression profile correlating with MYCN mRNA levels in NB88, a series of 88 neuroblastoma tumors, and therefore represent in vivo relevant MYCN pathway genes. This 157-gene signature identified very poor prognosis tumors in NB88 and independent neuroblastoma cohorts and was more powerful than MYCN amplification or MYCN expression alone. Remarkably, this signature also identified poor outcome of a group of tumors without MYCN amplification. Most of these tumors have low MYCN mRNA levels but high nuclear MYCN protein levels, suggesting stabilization of MYCN at the protein level. One tumor has an MYC amplification and high MYC expression. Chip-on-chip analyses showed that most genes in this signature are directly regulated by MYCN. MYCN induces genes functioning in cell cycle and DNA repair while repressing neuronal differentiation genes. The functional MYCN-157 signature recognizes classical neuroblastoma with MYCN amplification, as well as a newly identified group marked by MYCN protein stabilization.
神经母细胞瘤是一种儿童交感神经系统肿瘤。MYCN（V-myc 髓母细胞瘤病毒相关癌基因，神经母细胞瘤衍生[禽类]）在 20%的神经母细胞瘤中扩增，这些肿瘤预后不良。然而，没有 MYCN 扩增的肿瘤也可能预后不良。在这里，我们通过 shRNA 介导的 MYCN 沉默在神经母细胞瘤细胞中鉴定了 MYCN 的下游靶标。从这些靶标中，有 157 个基因在 NB88（一系列 88 个神经母细胞瘤肿瘤）中与 MYCN mRNA 水平相关的表达谱，因此代表了体内相关的 MYCN 通路基因。该 157 个基因签名在 NB88 和独立的神经母细胞瘤队列中鉴定出预后非常差的肿瘤，并且比 MYCN 扩增或 MYCN 表达更有效。值得注意的是，该特征还鉴定出一组无 MYCN 扩增的肿瘤的不良预后。这些肿瘤中的大多数具有低水平的 MYCN mRNA，但高水平的核 MYCN 蛋白水平，表明 MYCN 在蛋白质水平上稳定。一个肿瘤具有 MYC 扩增和高 MYC 表达。芯片分析显示，该特征中的大多数基因都直接受到 MYCN 的调控。MYCN 诱导细胞周期和 DNA 修复的基因，同时抑制神经元分化基因。功能性 MYCN-157 特征识别具有 MYCN 扩增的经典神经母细胞瘤，以及一个新发现的以 MYCN 蛋白稳定为特征的新群体。
