Reduced expression of GNA11 and silencing of MCT1 in human breast cancers
Reduced expression of GNA11 and silencing of MCT1 in human breast cancers
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DOI：
10.1159/000070297
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发表时间：
2003-01-01
期刊：
影响因子：
3.5
通讯作者：
Ushijima, T
中科院分区：
文献类型：
--
作者：
Asada, K;Miyamoto, K;Ushijima, T
基因甲基化状态的改变通常与其表达的改变有关。基于 CpG 甲基化差异的基因组扫描技术、甲基化敏感的代表性差异分析，分离出人类乳腺癌中高甲基化的 DNA 片段。从鸟嘌呤核苷酸结合蛋白 α-11 (GNA11) 的内含子 1 中分离出 DNA 片段。 RTPCR 分析显示，16 种乳腺癌中有 10 种 GNA11 mRNA 表达降低，免疫组织化学观察到 16 种乳腺癌中有 14 种 GNA11 产物（异源三聚体 G 蛋白的 Gall 亚基）的免疫反应性降低。 GNA11 5' 区域或内含子 1 的 CpG 岛 (CGI) 甲基化与其表达减少没有显示出明显的相关性。另一个 DNA 片段是从单羧酸转运蛋白 1 (MM) 5' 上游区域的 CGI 中分离出来的，并在 20 例乳腺癌中的 4 例中被甲基化。 CGI 在人乳腺癌细胞系 MDA-MB-231 中也被甲基化，定量 RT-PCR 显示其表达在细胞系中几乎消失。通过用去甲基化剂 5-aza-2'-脱氧胞苷处理细胞，甲基化被去除并恢复表达。 GNA11 参与促性腺激素释放激素受体的信号传导，对细胞生长产生负调节。 MCT1 参与丁酸盐的细胞运输，从而诱导细胞分化。这两个基因的下调被认为与人类乳腺癌有关。
Alteration in the methylation status of a gene is often associated with its altered expression. Based on a genome scanning technique for differences in CpG methylations, methylation-sensitive representational difference analysis, DNA fragments hypermethylated in a human breast cancer were isolated. A DNA fragment was isolated from intron 1 of guanine-nucleotide-binding protein alpha-11 (GNA11). mRNA expression of GNA11 was shown to be decreased in 10 of 16 breast cancers by RTPCR analysis, and the immunoreactivity of the GNA11 product, Gall subunit of heterotrimeric G-protein, was observed to be reduced in 14 of the 16 cancers by immunohistochemistry. Methylation of a CpG island (CGI) in the 5' region of GNA11 or that of intron 1 did not show a clear correlation with its decreased expression. Another DNA fragment was isolated from a CGI in the 5' upstream region of monocarboxylate transporter 1 (MM), and was methylated in 4 of 20 breast cancers. The CGI was also methylated in a human breast cancer cell line, MDA-MB-231, and quantitative RT-PCR showed that its expression was almost lost in the cell line. By treatment of the cells with a demethylating agent, 5-aza-2'-deoxycytidine, the methylation was removed and the expression was restored. GNA11 is involved in signalling of gonadotropin-releasing hormone receptor, which negatively regulates cell growth. MCT1 is involved in cellular transportation of butyrate, which induces cellular differentiation. Downregulation of these two genes was suggested to be involved in human breast cancers.