Characterization of Rearrangements Involving the ALK Gene Reveals a Novel Truncated Form Associated with Tumor Aggressiveness in Neuroblastoma
Characterization of Rearrangements Involving the ALK Gene Reveals a Novel Truncated Form Associated with Tumor Aggressiveness in Neuroblastoma
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DOI：
10.1158/0008-5472.can-12-1242
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发表时间：
2013-01-01
期刊：
影响因子：
11.2
通讯作者：
Janoueix-Lerosey, Isabelle
中科院分区：
文献类型：
--
作者：
Cazes, Alex;Louis-Brennetot, Caroline;Janoueix-Lerosey, Isabelle
已在神经母细胞瘤（NB）（一种外周神经系统癌症）的散发性和家族性病例中发现ALK基因的激活突变，并被认为是该受体在该儿科肿瘤中致癌激活的主要机制。为了解决ALK激活可能通过在其他癌症中检测到的基因组重排发生的可能性，我们首先利用高分辨率阵列比较基因组杂交来搜索NB样本中的ALK重排。使用捕获/配对末端测序和FISH实验的互补实验，在几种NB细胞系和原发性肿瘤中充分表征了各种类型的重排，包括部分增益或扩增。在CLB-Bar细胞系中，我们描述了一种与ALK基因座扩增相关的基因组重排，导致表达一种170 kDa的蛋白，该蛋白缺乏由外显子4至11编码的部分胞外结构域，称为ALK（Delta 4-11）。在诊断和复发时对肿瘤的基因组DNA进行分析，发现ALK基因在诊断时扩增，但重排的ALK等位基因仅在复发阶段观察到，这表明它可能与肿瘤的侵袭性有关。ALK（Delta 4-11）变体在NIH 3 T3细胞中稳定表达后显示出一致性、致癌性和致瘤性。此外，我们记录了这种变体的组成性激酶活性增加，以及成熟和保留到细胞内隔室受损。这些结果表明，基因组重排是ALK点突变导致受体活化的替代机制。Cancer Res; 73（1）; 195-204. (C)2012年AACR。
Activating mutations of the ALK gene have been identified in sporadic and familial cases of neuroblastoma (NB), a cancer of the peripheral nervous system, and are thought to be the primary mechanism of oncogenic activation of this receptor in this pediatric neoplasm. To address the possibility that ALK activation may occur through genomic rearrangements as detected in other cancers, we first took advantage of high-resolution array-comparative genomic hybridization to search for ALK rearrangements in NB samples. Using complementary experiments by capture/paired-end sequencing and FISH experiments, various types of rearrangements were fully characterized, including partial gains or amplifications, in several NB cell lines and primary tumors. In the CLB-Bar cell line, we described a genomic rearrangement associated with an amplification of the ALK locus, leading to the expression of a 170 kDa protein lacking part of the extracellular domain encoded by exons 4 to 11, named ALK(Delta 4-11). Analysis of genomic DNA from the tumor at diagnosis and relapse revealed that the ALK gene was amplified at diagnosis but that the rearranged ALK allele was observed at the relapse stage only, suggesting that it may be implicated in tumor aggressiveness. Consistently, oncogenic and tumorigenic properties of the ALK(Delta 4-11) variant were shown after stable expression in NIH3T3 cells. Moreover, we documented an increased constitutive kinase activity of this variant, as well as an impaired maturation and retention into intracellular compartments. These results indicate that genomic rearrangements constitute an alternative mechanism to ALK point mutations resulting in receptor activation. Cancer Res; 73(1); 195-204. (C) 2012 AACR.