Methylation mediated silencing of MicroRNA-1 gene and its role in hepatocellular carcinogenesis.
Methylation mediated silencing of MicroRNA-1 gene and its role in hepatocellular carcinogenesis.
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DOI：
10.1158/0008-5472.can-07-6655
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发表时间：
2008-07-01
期刊：
影响因子：
11.2
通讯作者：
Jacob, Samson T.
中科院分区：
文献类型：
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作者：
Datta, Jharna;Kutay, Huban;Nasser, Mohd W.;Nuovo, Gerard J.;Wang, Bo;Majumder, Sarmila;Liu, Chang-Gong;Volinia, Stefano;Croce, Carlo M.;Schmittgen, Thomas D.;Ghoshal, Kalpana;Jacob, Samson T.
microRNA（miRs）是一类小的（~21个核苷酸）非编码RNA，通常负调控基因表达。一些携带CpG岛（CGI）的miR经历甲基化介导的沉默，这是许多肿瘤抑制基因的特征。为了鉴定肝癌中的此类miR，在用5-氮杂胞苷（DNA低甲基化剂）和/或阿司他丁A（组蛋白脱乙酰酶抑制剂）处理的肝癌（HCC）细胞系中分析microRNA表达谱。结果表明，这些表观遗传药物差异调节肝癌细胞中一些miR的表达，特别是miR-1-1。跨miR-1-1的外显子1和内含子1的CGI在HCC细胞系和原发性人HCC中甲基化，但在匹配的肝组织中未甲基化。miR-1-1基因在DNMT 1 −/− HCT 116细胞中被低甲基化和激活，但在DNMT 3B null细胞中没有，表明DNMT 1在其甲基化中起关键作用。与匹配的正常肝组织相比，原发性人肝细胞癌中的miR-1表达也显著降低。miR-1在HCC细胞中的异位表达抑制细胞生长，降低复制潜力和克隆形成存活。异位miR-1显著降低了FoxP 1和MET的表达，它们在各自的3′-UTR中分别含有3个和2个miR-1同源位点。几种miR-1靶点包括FoxP 1、MET和HDAC 4在原发性人HCC中的上调以及它们在5-AzaC处理的HCC细胞中的表达下调表明它们在肝癌发生中的作用。miR-1重新表达后抑制细胞周期进程和诱导凋亡是DNA低甲基化剂抑制肝癌细胞生长的机制之一。
MicroRNAs (miRs) are a class of small (~21 nucleotide) noncoding RNAs that, in general, negatively regulate gene expression. Some miRs harboring CpG islands (CGIs) undergo methylation-mediated silencing, a characteristic of many tumor suppressor genes. To identify such miRs in liver cancer the microRNA expression profile was analyzed in hepatocarcinoma (HCC) cell lines treated with 5-azacytidine (DNA hypomethylating agent) and/or trichostatin A (histone deacetylase inhibitor). The results showed that these epigenetic drugs differentially regulate expression of a few miRs, particularly miR-1-1, in HCC cells. The CGI spanning exon 1 and intron 1 of miR-1-1 was methylated in HCC cell lines and in primary human HCCs but not in matching liver tissues. The miR-1-1 gene was hypomethylated and activated in DNMT1−/− HCT 116 cells but not in DNMT3B null cells, indicating a key role for DNMT1 in its methylation. miR-1 expression was also markedly reduced in primary human hepatocellular carcinomas compared to matching normal liver tissues. Ectopic expression of miR-1 in HCC cells inhibited cell growth, reduced replication potential and clonogenic survival. The expression of FoxP1 and MET harboring three and two miR-1 cognate sites, respectively, in their respective 3′-UTRs, was markedly reduced by ectopic miR-1. Upregulation of several miR-1 targets including FoxP1, MET and HDAC4 in primary human HCCs and downregulation of their expression in 5-AzaC-treated HCC cells suggest their role in hepatocarcinogenesis. The inhibition of cell cycle progression and induction of apoptosis following re-expression of miR-1 are one of the mechanisms by which DNA hypomethylating agents suppress hepatocarcinoma cell growth.