RASSF1A promoter region CpG island hypermethylation in phaeochromocytomas and neuroblastoma tumours
RASSF1A promoter region CpG island hypermethylation in phaeochromocytomas and neuroblastoma tumours
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DOI：
10.1038/sj.onc.1204968
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发表时间：
2001-11-08
期刊：
影响因子：
8
通讯作者：
Latif, F
中科院分区：
文献类型：
--
作者：
Astuti, D;Agathanggelou, A;Latif, F
染色体3 p的缺失在许多类型的肿瘤中是常见的，包括神经嵴肿瘤，如神经母细胞瘤（NB）和嗜铬细胞瘤。最近，我们分离出几个候选肿瘤抑制基因（TSGs）从一个120 kb的关键间隔在3p21.3定义的重叠纯合缺失在肺和乳腺肿瘤细胞系。虽然肺癌和乳腺癌中候选TSG的突变分析仅显示罕见的突变，但其中一种基因（RASSF 1A）的表达在大多数分析的肺肿瘤细胞系中不存在。随后，RASSF 1A启动子区域的CpG岛甲基化在大多数小细胞肺癌中得到证实，在非小细胞肺癌中程度较低。为了研究3 p TSGs在神经嵴肿瘤中的作用，我们（a）分析了嗜铬细胞瘤的3 p等位基因丢失（n = 41）和RASSF 1A甲基化（n = 23），（B）研究了67例神经母细胞瘤的RASSF 1A失活。46%的嗜铬细胞瘤显示3 p等位基因丢失（3p21.3为38.5%）。RASSF 1A基因启动子区甲基化在22%（5/23）的散发性嗜铬细胞瘤和55%（37/67）的神经母细胞瘤中被发现，但未发现RASSF 1A基因突变。在两个神经母细胞瘤细胞系中，RASSF 1A甲基化与RASSF 1A表达的丧失相关，并且在用去甲基化剂5-氮杂胞苷处理后RASSF 1A表达恢复。由于CASP 8基因的频繁甲基化在神经母细胞瘤中也有报道，我们研究了RASSF 1A和CASP 8甲基化是独立的还是相关的事件。CASP 8甲基化在有RASSF 1A甲基化的神经母细胞瘤中为56%，在无RASSF 1A甲基化的神经母细胞瘤中为17%（P = 0.0031）。这些结果表明：（a）RASSF 1A因过度甲基化而失活是神经嵴肿瘤发生中的常见事件，特别是神经母细胞瘤，并且RASSF 1A是候选的3p21.3神经母细胞瘤TSG;（B）神经母细胞瘤的一个亚群可能以CpG岛甲基化表型为特征。
Deletions of chromosome 3p are frequent in many types of neoplasia including neural crest tumours such as neuroblastoma (NB) and phaeochromocytoma. Recently we isolated several candidate tumour suppressor genes (TSGs) from a 120 kb critical interval at 3p21.3 defined by overlapping homozygous deletions in lung and breast tumour lines. Although mutation analysis of candidate TSGs in lung and breast cancers revealed only rare mutations, expression of one of the genes (RASSF1A) was absent in the majority of lung tumour cell lines analysed. Subsequently methylation of a CpG island in the promoter region of RASSF1A was demonstrated in a majority of small cell lung carcinomas and to a lesser extent in non-small cell lung carcinomas. To investigate the role of 3p TSGs in neural crest tumours, we (a) analysed phaeochromocytomas for 3p allele loss (n = 41) and RASSF1A methylation (n = 23) and (b) investigated 67 neuroblastomas for RASSF1A inactivation. 46% of phaeochromocytomas showed 3p allele loss (38.5% at 3p21.3). RASSF1A promoter region hypermethylation was found in 22% (5/23) of sporadic phaeochromocytomas and in 55% (37/67) of neuroblastomas analysed but RASSF1A mutations were not identified. In two neuroblastoma cell lines, methylation of RASSF1A correlated with loss of RASSF1A expression and RASSF1A expression was restored after treatment with the demethylating agent 5-azacytidine. As frequent methylation of the CASP8 gene has also been reported in neuroblastoma, we investigated whether RASSF1A and CASP8 methylation were independent or related events. CASP8 methylation was detected in 56% of neuroblastomas with RASSF1A methylation and 17% without RASSF1A methylation (P = 0.0031). These results indicate that (a) RASSF1A inactivation by hypermethylation is a frequent event in neural crest tumorigenesis, particularly neuroblastoma, and that RASSF1A is a candidate 3p21.3 neuroblastoma TSG and (b) a subset of neuroblastomas may be characterized by a CpG island methylator phenotype.