Theissen Jessica, Boensch Marc, Spitz Ruediger, Betts David, Stegmaier Sabine, Christiansen Holger, Niggli Felix, Schilling Freimut, Schwab Manfred, Simon Thorsten, Westermann Frank, Berthold Frank, Hero Barbara
Department of Pediatric Oncology and Hematology, Children's Hospital, University of Cologne, Cologne, Germany.
Clin Cancer Res. 2009 Mar 15;15(6):2085-90. doi: 10.1158/1078-0432.CCR-08-1648. Epub 2009 Mar 10.
MYCN amplification is an important therapy-stratifying marker in neuroblastoma. Fluorescence in situ hybridization with signal detection on the single-cell level allows a critical judgement of MYCN intratumoral heterogeneity.
The MYCN status was investigated by fluorescence in situ hybridization at diagnosis and relapse. Heterogeneity was defined as the simultaneous presence of amplified cells (>/=5 cells per slide) and nonamplified cells within one tumor or sequential change of the amplification status during the course of the disease. Likewise, heterogeneity can be detected between primary tumor and metastasis.
From 1,341 patients analyzed, 1,071 showed no amplification, 250 showed homogeneous amplification, and 20 patients showed MYCN heterogeneity. Of the patients with heterogeneity, 12 of 20 had clusters of MYCN amplifications, 3 of 20 had amplified single cells, 3 of 20 showed MYCN amplifications in the bone marrow but not in the primary tumor, and 2 of 20 acquired MYCN amplification during the course of the disease. All stage 4 patients were treated according to high-risk protocols; 7 of 8 later progressed. Four patients with localized disease were treated according to high-risk protocol because of MYCN-amplified clusters; 1 of 4 later progressed. One patient treated with mild chemotherapy experienced progression. Seven patients with localized/4S disease underwent no chemotherapy: 4 of 5 patients with MYCN heterogeneity at diagnosis remained disease-free, and 1 of 5 experienced local progression. Two patients had normal MYCN status at diagnosis but acquired MYCN amplification during the course of the disease.
MYCN heterogeneity is rare. Our results suggest that small amounts of MYCN-amplified cells are not correlated to adverse outcomes. More patients with heterogeneity are warranted to clarify the role of MYCN heterogeneity for risk classification.
MYCN基因扩增是神经母细胞瘤中一种重要的治疗分层标志物。单细胞水平上的荧光原位杂交信号检测能够对MYCN基因的肿瘤内异质性进行关键判断。
通过荧光原位杂交在诊断和复发时研究MYCN基因状态。异质性定义为在一个肿瘤内同时存在扩增细胞（每张玻片≥5个细胞）和未扩增细胞，或在疾病过程中扩增状态的序贯变化。同样，在原发性肿瘤和转移灶之间也可检测到异质性。
在分析的1341例患者中，1071例未出现扩增，250例表现为均匀扩增，20例表现为MYCN基因异质性。在异质性患者中，20例中有12例存在MYCN基因扩增簇，20例中有3例存在单个扩增细胞，20例中有3例在骨髓中出现MYCN基因扩增但原发性肿瘤中未出现，20例中有2例在疾病过程中获得MYCN基因扩增。所有IV期患者均按照高危方案进行治疗；8例中有7例随后病情进展。4例局限性疾病患者因存在MYCN基因扩增簇而按照高危方案进行治疗；4例中有1例随后病情进展。1例接受轻度化疗的患者病情进展。7例局限性/4S期疾病患者未接受化疗：诊断时存在MYCN基因异质性的5例患者中有4例无病生存，5例中有1例出现局部进展。2例患者诊断时MYCN基因状态正常，但在疾病过程中获得MYCN基因扩增。
MYCN基因异质性罕见。我们的结果表明，少量MYCN基因扩增细胞与不良预后无关。需要更多异质性患者来阐明MYCN基因异质性在风险分类中的作用。
