Mechanism of no gene expression of hMLH1 in sporadic colorectal cancers : Identification of transcription factors and its establishment of detection method.

散发性结直肠癌hMLH1基因不表达的机制：转录因子的鉴定及其检测方法的建立。

基本信息

批准号：
10671223
负责人：
HEMMI Hiromichi
金额：
$ 2.05万
依托单位：
TOHO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

项目摘要

In 1993 and 1994, the hMSH2 and hMLH1 genes have been identified as responsible genes of hereditary nonpolyposis colorectal cancer (HNPCC). Defects of these genes are also associated with generation and development of many cancers. In this study, we focused in the mechanism of gene expression of hMLH1.The major findings obtained during the project years are follows :(1) Identification of promoter region essential for gene expressionBy reporter gene analysis, a region containing -301 to -76 is essential for the gene expression.(2) Protein binding regions and its consensus sequences for transcription factorsSix protein binding regions were identified by in vivo footprinting analysis. One CCAAT region was found by search program for transcription factor binding sites and protein binding to this site was confirmed by a get mobility shift assay. Among 7 sites, 3 sites were important for transcription. These results indicate that at least two or three regions are essential for the hMLH1 gene expression and also suggest that the factors may be unknown.(3) Mutations in promoter region in sporadic colorectal cancerWhen we searched the mutation in the promoter region of hMLH1 gene of tumor DNA of 90 sporadic colorectal cancer, 2 single nucleotide substitutions were found at -72 and -86. The former one is polymorphism, because same mutation was found in healthy population with high frequency. The later one was found in only cancer population and showed 70% of transcriptional activity compared to wild-type.It is required for further investigation to identify the transcription factor(s) and its dysfunctional status in colorectal cancer.

在1993年和1994年，HMSH2和HMLH1基因已被鉴定为遗传性非多型结直肠癌（HNPCC）的负责基因。这些基因的缺陷也与许多癌症的产生和发育有关。在这项研究中，我们专注于HMLH1基因表达的机制。在项目年中获得的主要发现如下：（1）鉴定基因表达的启动子区域对记者的基因分析必不可少，一个含-301至-76的区域对于基因表达而言是必不可少的。分析。通过搜索程序发现了一个CCAAT区域的转录因子结合位点，并通过GET迁移率转移测定法证实了与该位点的蛋白质结合。在7个站点中，有3个地点对于转录很重要。这些结果表明，至少两个或三个区域对于HMLH1基因表达至关重要，也表明这些因素可能未知。（3）当我们搜索了零星结直肠癌的启动子区域的突变，我们搜索了90个孢子结肠癌的90个sporactic molaradic癌症肿瘤DNA的启动子中的突变，2单核替代物。前者是多态性的，因为在高频的健康人群中发现了相同的突变。与野生型相比，后来仅在癌症人群中发现了70％的转录活性。进一步研究以确定转录因子及其在结直肠癌中的功能失调状态所必需。