Epigenetic silencing of miR-137 is an early event in colorectal carcinogenesis.
Epigenetic silencing of miR-137 is an early event in colorectal carcinogenesis.
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DOI：
10.1158/0008-5472.can-10-0622
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发表时间：
2010-08-15
期刊：
影响因子：
11.2
通讯作者：
Goel A
中科院分区：
文献类型：
--
作者：
Balaguer F;Link A;Lozano JJ;Cuatrecasas M;Nagasaka T;Boland CR;Goel A
microRNA的整体下调是结直肠癌（CRC）的常见特征。而CpG岛超甲基化构成了一种机制的miRNA沉默，这一领域在很大程度上仍然是未开发的。在此，我们描述了miR-137的表观遗传调控及其在结直肠癌发生中的作用。我们确定了一组6个CRC细胞系和409个结直肠组织（21个来自健康个体的正常结肠粘膜（N-N），160个原发性CRC组织及其相应的正常粘膜（N-C）和68个腺瘤）中miR-137 CpG岛的甲基化状态。采用TaqMan RT-PCR和原位杂交技术分析miR-137的表达。进行miR-137的体外功能分析。使用生物信息学和转录组学方法的组合鉴定miR-137的基因靶点。我们实验验证了miRNA：mRNA相互作用。miR-137 CpG岛的甲基化是一种癌症特异性事件，经常在CRC细胞系（100%）、腺瘤（82.3%）和CRC（81.4%）中观察到，但在N-C（14.4%，CRC p<0.0001）和N-N（4.7%，CRC p<0.0001）中未观察到。miR-137的表达仅限于正常黏膜的结肠细胞，且与甲基化水平呈负相关。在CRC细胞中转染miR-137前体显著抑制细胞增殖。miR-137转染后的基因表达谱发现了新的潜在mRNA靶点。我们验证了miR-137和LSD-1之间的相互作用。我们的数据首先表明miR-137在结肠中作为肿瘤抑制因子，并且经常被启动子超甲基化沉默。结直肠腺瘤中miR-137的甲基化沉默表明其是早期事件，具有预后和治疗意义。
Global downregulation of microRNAs is a common feature in colorectal cancer (CRC). Whereas CpG island hypermethylation constitutes a mechanism for miRNA silencing, this field largely remains unexplored. Herein, we describe the epigenetic regulation of miR-137 and its contribution to colorectal carcinogenesis. We determined the methylation status of miR-137 CpG island in a panel of six CRC cell lines and 409 colorectal tissues (21 normal colonic mucosa from healthy individuals (N-N), 160 primary CRC tissues and their corresponding normal mucosa (N-C) and 68 adenomas). TaqMan RT-PCR and in situ hybridization were used to analyze miR-137 expression. In vitro functional analysis of miR-137 was performed. Gene targets of miR-137 were identified using a combination of bio-informatic and transcriptomic approaches. We experimentally validated the miRNA:mRNA interactions. Methylation of the miR-137 CpG island was a cancer-specific event, and was frequently observed in CRC cell lines (100%), adenomas (82.3%) and CRC (81.4%) but not in N-C (14.4%, p<0.0001 for CRC) and N-N (4.7%, p<0.0001 for CRC). Expression of miR-137 was restricted to the colonocytes in normal mucosa, and inversely correlated with the level of methylation. Transfection of miR-137 precursor in CRC cells significantly inhibited cell proliferation. Gene expression profiling after miR-137 transfection discovered novel potential mRNA targets. We validated the interaction between miR-137 and LSD-1. Our data firstly indicate that miR-137 acts as a tumor suppressor in the colon and is frequently silenced by promoter hypermethylation. Methylation-silencing of miR-137 in colorectal adenomas suggests it to be an early event, which has prognostic and therapeutic implications.