Claudin-1 Has Tumor Suppressive Activity and Is a Direct Target of RUNX3 in Gastric Epithelial Cells
Claudin-1 Has Tumor Suppressive Activity and Is a Direct Target of RUNX3 in Gastric Epithelial Cells
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DOI：
10.1053/j.gastro.2009.08.044
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发表时间：
2010-01-01
期刊：
影响因子：
29.4
通讯作者：
Ito, Yoshiaki
中科院分区：
文献类型：
--
作者：
Chang, Ti Ling;Ito, Kosei;Ito, Yoshiaki
背景和目的：转录因子 RUNX3 是一种胃肿瘤抑制因子。与非致瘤性 Runx3(+/+) 细胞相比，致瘤性 Runx3(-/-) 胃上皮细胞彼此附着较弱。我们准备鉴定促进细胞间接触的 RUNX3 靶基因，以提高我们对 RUNX3 在抑制胃癌发生中的作用的理解。方法：我们比较了 Runx3(+/+) 和 Runx3(-/-) 细胞的基因表达谱，并观察到 Runx3(-/-) 细胞中与细胞间粘附相关的基因的下调。使用报告基因、迁移率变化和染色质免疫沉淀测定来检查 RUNX3 对这些基因的调节。对人胃肿瘤进行肿瘤发生测定和免疫组织学分析，以确认候选基因在胃肿瘤发展中的作用。结果：迁移率变化和染色质免疫沉淀分析表明，编码紧密连接蛋白 claudin-1 的基因的启动子活性通过 RUNX3 与 RUNX 共有位点的结合而上调。通过恢复claudin-1表达，以及敲低claudin-1，Runx3(-/-)小鼠胃上皮细胞的致瘤性显着降低。增加人胃癌细胞的致瘤性。在人类正常胃上皮和癌症中观察到 RUNX3 和 Claudin-1 的同时表达。结论：紧密连接蛋白claudin-1具有胃肿瘤抑制活性，并且是RUNX3的直接转录靶标。 Claudin-1 在上皮-间质转化过程中下调；因此，RUNX3 可能作为肿瘤抑制因子来拮抗上皮-间质转化。
BACKGROUND & AIMS: The transcription Factor RUNX3 is a gastric tumor suppressor. Tumorigenic Runx3(-/-) gastric epithelial cells attach weakly to each other, compared with nontumorigenic Runx3(+/+) cells. We alined to identify RUNX3 target genes that promote cell-cell contact to Improve our understanding of RUNX3's role in Suppressing gastric carcinogenesis. METHODS: We compared gene expression profiles of Runx3(+/+) and Runx3(-/-) cells and observed down-regulation of genes associated with cell-cell adhesion in Runx3(-/-) cells. Reporter, mobility shift, and chromatin immunoprecipitation assays were used to examine the regulation of these genes by RUNX3. Tumorigenesis assays and immunohistologic, analyses of human gastric tumors were performed to confirm the role of the candidate genes ill gastric tumor development. RESULTS: Mobility shift and chromatin immunoprecipitation assays revealed that the promoter activity of the gene that encodes the tight Junction protein claudin-1 was up-regulated via the binding of RUNX3 to the RUNX consensus sites. The tumorigenicity of gastric epithelial cells From Runx3(-/-) mice was significantly reduced by restoration of claudin-1 expression, whereas knockdown of claudin-1. increased the tumorigenicity of human gastric cancer cells. Concomitant expression of RUNX3 and claudin-1 was observed in human normal gastric epithelium and cancers. CONCLUSIONS: The tight junction protein claudin-1 has gastric tumor suppressive activity and is a direct transcriptional target of RUNX3. Claudin-1 is down-regulated during the epithelial-mesenchymal transition; RUNX3 might therefore act as a tumor suppressor to antagonize the epithelial-mesenchymal transition.