Alterations of DNA mismatch repair proteins and microsatellite instability levels in gastric cancer cell lines
Alterations of DNA mismatch repair proteins and microsatellite instability levels in gastric cancer cell lines
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DOI：
10.1038/labinvest.3700117
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发表时间：
2004-07-01
影响因子：
5
通讯作者：
Sepulveda, AR
中科院分区：
文献类型：
--
作者：
Yao, Y;Tao, H;Sepulveda, AR
DNA错配修复（MMR）蛋白的改变导致微卫星不稳定性（MSI）、靶基因突变积累增加和癌症发展。大约三分之一的胃癌表现为高水平微卫星不稳定性（MSI-High），低水平微卫星不稳定性（MSI-Low）经常被检测到。为了确定胃癌细胞系中MMR蛋白水平的变化或主要DNA MMR基因的突变是否与MSI- low和MSI- high相关，使用5个微卫星标记的多克隆分析确定了14个胃癌细胞系的MSI状态（MSI- high， MSI- low或MS-Stable (MSS)）。Western blot检测hMLH1、hMSH2、hMSH6、hPMS2、hPMS1蛋白水平。对hMLH1和hMSH2进行序列分析，并检测hMLH1启动子的甲基化状态。细胞系SNU1和SNU638表现出MSI-High， hMLH1和hPMS2基本缺失，hPMS1和hMSH6蛋白水平降低。在SNU638细胞中，hMLH1启动子区域高甲基化。MKN28、MKN87、KATOIII和SNU601细胞系显示MSI-Low。MSI-Low状态细胞的MMR蛋白水平与MISS细胞相似。在胃癌细胞中，MutL MMR蛋白（hMLH1、hPMS2和hPMS1）表达水平的显著降低与MSI高水平突变有关。MSI-Low状态的胃癌细胞系在主要DNA MMR蛋白水平和DNA错配修复基因hMSH2和hMLH1的突变上没有明显变化。这些具有良好特征的胃癌细胞系为进一步了解DNA MMR缺陷在癌症发生、进展和预后中的作用提供了宝贵的资源。
Alterations in DNA mismatch repair (MMR) proteins result in microsatellite instability (MSI), increased mutation accumulation at target genes and cancer development. About one-third of gastric cancers display high-level microsatellite instability (MSI-High) and low-level microsatellite instability (MSI-Low) is frequently detected. To determine whether variations in the levels of MMR proteins or mutations in the main DNA MMR genes are associated with MSI-Low and MSI-High in gastric cancer cell lines, the MSI status (MSI-High, MSI-Low or MS-Stable (MSS)) of 14 gastric cancer lines was determined using multiple clone analysis with a panel of five microsatellite markers. Protein levels of hMLH1, hMSH2, hMSH6, hPMS2 and hPMS1 were determined by Western blot. Sequence analysis of hMLH1 and hMSH2 was performed and the methylation status of the hMLH1 promoter was examined. The cell lines SNU1 and SNU638 showed MSI-High, decreased to essentially absent hMLH1 and hPMS2 and reduced hPMS1 and hMSH6 protein levels. The hMLH1 promoter region was hypermethylated in SNU638 cells. The MKN28, MKN87, KATOIII and SNU601 cell lines showed MSI-Low. The MMR protein levels of cells with MSI-Low status was similar to the levels detected in MISS cells. A marked decrease in the expression levels of MutL MMR proteins (hMLH1, hPMS2 and hPMS1) is associated with high levels of MSI mutations in gastric cancer cells. Gastric cancer cell lines with MSI-Low status do not show significant changes in the levels of the main DNA MMR proteins or mutations in the DNA mismatch repair genes hMSH2 and hMLH1. These well-characterized gastric cancer cell lines are a valuable resource to further our understanding of DNA MMR deficiency in cancer development, progression and prognosis.