胃癌细胞中S100A4蛋白核转位的机制及其核功能研究

Many studies have reported recently that nuclear expression of S100A4 protein is closely related to the metastasis of many kinds of cancers and poor prognosis of the cancer patients ,including gastric cancer. But the mechanisms of nuclear translocation of S100A4 and the function of nuclear S100A4 are still to be uncovered. We will investigate the effect of IL-1β on the nuclear translocation of S100A4 in gastric cancer cells, so as to unravel the mechanisms of nuclear translocation of S100A4 in it. Then we will perform the genome-wide mapping of S100A4 binding by ChIP-Sequencing technology , and we will also detect the differentially expressed gene profile in the downstream of S100A4 by Microarray . By comparison of the above two results, we will extensively learn the mechanisms by which S100A4 regulates the downstream gene expression, which means we can understand the molecular biological function of nuclear S100A4. By studying the effect of nuclear S100A4 on the stem-like properties of gastric cancer cells , we will learn the cellular biological function of nuclear S100A4. We will detect the expression of S100A4 , CA Ⅸ,IL-1β,the products of S100A4 target genes and CD44 etc, mainly paying attention to the correlation of nuclear S100A4 with other molecules , the clinicopathological characteristics of gastric cancers and the prognosis of the patients. So we can learn the clinicopathological significance of nuclear S100A4 and its mechanisms. We hope to unravel novel cellular and molecular mechanism for S100A4 by the study above on nuclear S100A4，finding new markers and targets for the diagnosis and therapy of gastric cancer in the context of S100A4 pathway or networks .

近年来一些研究报道细胞核中S100A4蛋白与多种肿瘤包括胃癌转移及病人预后密切相关，而肿瘤细胞S100A4蛋白核转位的机制及其核功能仍不清楚。本课题研究IL-1β对胃癌细胞中S100A4蛋白核转位的影响，初步探明其核转位的分子机制；经ChIP-Seq 研究S100A4与全基因组基因结合谱，基因芯片检测S100A4下游差异基因表达谱，将二者比对分析，全面认识胞核S100A4调控基因表达的机制即胞核S100A4的分子生物学功能。研究胞核S100A4蛋白对胃癌细胞干样特性的影响，认识其细胞生物学功能；检测胃癌标本中S100A4及IL-1β、CA Ⅸ、S100A4靶基因产物、CD44等表达，重点关注胞核S100A4与其他检测指标及胃癌临床病理特征及病人预后的关系，认识其临床病理学意义及机制。本研究可望揭示S100A4新的细胞分子作用机制，发现胃癌诊治的新标志物、新靶点。

近年来有研究表明，S100A4蛋白在多种肿瘤细胞的核中高表达，且与胃癌等肿瘤病人预后不良相关，提示细胞核中S100A4蛋白在肿瘤发生发展中具有重要作用，而肿瘤细胞S100A4蛋白核转位的机制及细胞核S100A4蛋白的功能尚不清楚。我们研究了胃癌细胞MGC803中S100A4蛋白核转位的机制、细胞核S100A4蛋白的分子生物学、细胞生物学功能以及其临床病理学意义等。结果表明，IL-1β促进胃癌细胞MGC803中S100A4蛋白核转位，且该效应经PI3K通路介导；应用基因芯片技术检测发现沉默S100A4表达后，MGC803细胞中有179个基因呈差异表达（38个基因上调，141个基因下调），从中选择了两个重要基因GDF15和FAM107B进行深入研究。ChIP-qPCR技术证明S100A4蛋白可与GDF15启动子结合，为细胞核S100A4蛋白调控GDF15基因转录提供了重要证据。功能研究表明，S100A4通过上调GDF15表达而促进胃癌细胞干样特性等；S100A4通过下调FAM107B表达而促进胃癌细胞增殖、迁移等特性；研究还表明，IL-1β经PI3K通路及S100A4介导促进胃癌细胞干样特性等。上述成果为加深理解胃癌细胞中S100A4蛋白核转位机制及细胞核S100A4蛋白的分子、细胞生物学功能提供了新线索，也证实了以S100A4为核心的新通路即IL-1β-PI3K-S100A4-GDF15或FAM107B的存在，以及该通路对胃癌细胞干样特性、增殖、迁移等特性的影响。胃癌组织芯片的研究结果正在分析中，细胞核S100A4蛋白的临床病理学意义有待揭示。其他的相关研究结果也具有重要意义。我们的研究结果加深了对胃癌发生、发展分子机制的认识，为研发胃癌诊治的新方法、新策略、新药物提供了有价值的靶点/靶通路，具有较重要的学术价值和良好的转化应用前景。