Involvement of epigenetically silenced microRNA-181c in gastric carcinogenesis
Involvement of epigenetically silenced microRNA-181c in gastric carcinogenesis
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DOI：
10.1093/carcin/bgq013
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发表时间：
2010-05-01
期刊：
影响因子：
4.7
通讯作者：
Yuasa, Yasuhito
中科院分区：
文献类型：
--
作者：
Hashimoto, Yutaka;Akiyama, Yoshimitsu;Yuasa, Yasuhito
microRNA（miRNA）的异常表达已在多种癌症中被报道。为了阐明miRNA在胃癌发生中的作用，我们进行了miRNA微阵列分析，并研究了5-aza-CdR处理的胃癌细胞系KATO-III中miRNA的表达变化。在微阵列分析中，发现与未处理的细胞相比，5-aza-CdR处理后的5种miRNA上调（> 3倍）。其中，miR-181 c和miR-432 AS在其上游序列中显示CpG岛，并且通过逆转录-聚合酶链反应分析验证了它们的上调。特别是，miR-181 c上调不仅在KATO-III中发现，而且在5-aza-CdR处理的另外两个胃癌细胞系和一个结直肠癌细胞系中也发现。16例原发性胃癌组织中有9例miR-181 c表达低于相应的非癌胃组织。在一些培养的和原代的胃癌细胞中观察到miR-181 c的上游区域的高甲基化信号，而miR-181 c表达为阴性或低表达。前体miR-181 c分子的转染诱导了两种胃癌细胞系KATO-III和MKN 45的生长下降。对于miR-181 c的靶点，通过前体miR-181 c分子转染后的互补DNA微阵列分析、miRNA靶点数据库的计算搜索和使用两个基因的3 '-非翻译区的报告基因测定来鉴定致癌的NOTCH 4和KRAS。这些结果表明miR-181 c可能通过甲基化沉默，并通过其靶基因如NOTCH 4和KRAS在胃癌发生中发挥重要作用。
Aberrant expression of microRNA (miRNA) has been reported in various cancers. To clarify the role of miRNA in gastric carcinogenesis, we performed miRNA microarray analysis and investigated expression changes of miRNAs in a 5-aza-2'-deoxycytidine (5-aza-CdR)-treated gastric cancer cell line, KATO-III. On microarray analysis, five miRNAs were found to be upregulated (> 3-fold) after 5-aza-CdR treatment compared with untreated cells. Among them, miR-181c and miR-432AS exhibited CpG islands in their upstream sequences on computational analysis, and their upregulation was verified by reverse transcription-polymerase chain reaction analyses. In particular, miR-181c upregulation was found not only in KATO-III but also in two other gastric and one colorectal cancer cell line with 5-aza-CdR treatment. Decreased expression of miR-181c was observed in 9 of 16 primary gastric carcinoma (GC) cases compared with the corresponding non-cancerous stomach tissues. Hypermethylation signals in the upstream region of miR-181c were observed in some cultured and primary GC cells with negative or low miR-181c expression. Transfection of the precursor miR-181c molecule induced decreased growth of two gastric cancer cell lines, KATO-III and MKN45. As for targets of miR-181c, oncogenic NOTCH4 and KRAS were identified by complementary DNA microarray analysis after precursor miR-181c molecule transfection, computational searches of miRNA target databases and reporter assaying using the 3'-untranslated regions of the two genes. These results indicate that miR-181c may be silenced through methylation and play important roles in gastric carcinogenesis through its target genes, such as NOTCH4 and KRAS.