Epigenetic silencing of prostaglandin E receptor 2 (PTGER2) is associated with progression of neuroblastomas
Epigenetic silencing of prostaglandin E receptor 2 (PTGER2) is associated with progression of neuroblastomas
复制标题
DOI：
10.1038/sj.onc.1210550
复制
发表时间：
2007-11-22
期刊：
影响因子：
8
通讯作者：
Inazawa, J.
中科院分区：
文献类型：
--
作者：
Sugino, Y.;Misawa, A.;Inazawa, J.
我们先前使用细菌人工染色体阵列甲基化CpG岛扩增方法鉴定了前列腺素受体基因簇，前列腺素D2受体（PTGDR）和前列腺素E受体2（PTGER 2），作为晚期神经母细胞瘤（NB）中DNA甲基化的可能靶点。其中，在本研究中，我们发现PTGER 2在NB细胞系中频繁沉默，特别是在MYCN扩增的那些细胞系中，通过表观遗传机制。在NB细胞系中，部分CpG岛内的DNA甲基化模式与PTGER 2表达呈负相关，而推定启动子区域内的组蛋白H3和H4去乙酰化以及组蛋白H3赖氨酸9甲基化与该基因的沉默更直接相关。与早期肿瘤相比，在晚期原发性NB中观察到更频繁的PTGER 2甲基化。通过瞬时和稳定转染恢复基因产物抑制缺乏内源性PTGER 2表达的NB细胞的生长。PTGER 2选择性激动剂布他前列素增加稳定表达外源性PTGER 2的NB细胞的细胞内环磷酸腺苷（cAMP）水平，抑制细胞生长并诱导细胞凋亡。8-溴-cAMP也抑制缺乏PTGER 2表达的NB细胞的生长，但不抑制表达该基因的细胞的生长。两者合计，这表明NB细胞可能通过PTGER 2的表观遗传沉默和/或在神经母细胞瘤发生期间下游cAMP依赖性通路的破坏而失去对PTGER 2介导的生长抑制/凋亡的响应性。
We previously identified a cluster of prostanoid receptor genes, prostaglandin D2 receptor (PTGDR) and prostaglandin E receptor 2 (PTGER2), as possible targets for DNA methylation in advanced types of neuroblastoma ( NB) using bacterial artificial chromosome array-based methylated CpG island amplification method. Among them, in this study, we found that PTGER2 was frequently silenced in NB cell lines, especially in those with MYCN amplification, through epigenetic mechanisms. In NB cell lines, DNA methylation pattern within a part of CpG island was inversely correlated with PTGER2 expression, and histone H3 and H4 deacetylation and histone H3 lysine 9 methylation within the putative promoter region were more directly correlated with silencing of this gene. Methylation of PTGER2 was observed more frequently in advanced-type of primary NBs compared with early-stage tumors. Growth of NB cells lacking endogenous PTGER2 expression was inhibited by restoration of the gene product by transient and stable transfection. A PTGER2-selective agonist, butaprost, increased intracellular cyclic adenosine monophosphate ( cAMP) level, inhibited cell growth and induced apoptosis of NB cells stably expressing exogenous PTGER2. 8-Bromo-cAMP also inhibited growth of NB cells lacking PTGER2 expression, but not cells expressing this gene. Taken together, it is suggested that NB cells may lose responsiveness to PTGER2-mediated growth inhibition/apoptosis through epigenetic silencing of PTGER2 and/or disruption of downstream cAMP-dependent pathway during the neuroblastomagenesis.