HOP/HSP90 复合物介导转录因子Snail核转位促进胃癌EMT的分子机制

To solve the metastasis of gastric cancer is difficulty in the present clinical work, and clarifing its mechanisms is very important. In previous study, we found HOP is highly expressed in gastric cancer, knockdown of HOP could inhibit cell epithelial-to-mesenchymal transitions and reduce metastasis in gastric cancer; the mass spectrometry analysis indicated the combination of HOP and Snail, Co-IP assay confirmed the protein interactions in previous experimental, and we found that HOP and Snail positively coordinated expression in cell nuclear during gastric cancer cell EMT; the HSP90 is the scaffold protein that binding HOP and Snail, it could nuclear translocation during cell EMT, and down-regualtion of HSP90 could block the combination of HOP and Snail, while knockdown of Snail did not affect the interaction HOP and HSP90. Thus, we propose the hypothesis that HOP/HSP90 complex mediates nuclear translocation of Snail and promotes EMT in gastric cancer. In this study, the genome-wide expression profile array would be used to detect downstream target genes and signaling pathway of HOP; Co-IP combined with gene gain- or loss- assay were used to demonstrate the hypothesis of HOP/HSP90 complex mediating Snail nuclear translocation; with the functional domain mutation and Co-IP, we would explore the interaction sites of HOP and HSP90 or HSP90 and Snail; we would detect our findings in vivo; finally, the correlation and clinical significance of each gene would be detected in clinical specimens. This study is supposed to reveal the mechanism of EMT in gastric cancer, and provide evidences for clinical diagnosis and treatment strategy of gastric cancer.

解决胃癌转移是目前临床工作的难点，阐明其机制极为重要。前期发现HOP在胃癌高表达，下调HOP抑制胃癌EMT并减少转移；质谱分析发现HOP与Snail蛋白结合，Co-IP证实其蛋白互作，并在胃癌EMT时在细胞核协同增高；HOP与Snail结合由HSP90为中介，HSP90在胃癌EMT时入核增多，下调HSP90阻断HOP/Snail结合，而敲除Snail不影响HOP/HSP90结合。基于此提出假设：HOP/HSP90复合物介导Snail核转位促进胃癌EMT。后续用全基因组表达谱芯片检测HOP下游靶基因和信号通路，并进行验证；用Co-IP联合基因差异表达，明确HOP/HSP90介导Snail核转位；用缺失突变联合Co-IP明确HOP/HSP90与HSP90/Snail互作位点；并在体内验证；最后在临床标本分析各基因相关性和临床意义。本项目有助于揭示胃癌EMT机制，并为胃癌临床诊疗策略提供新思路

本项目证实HSP70/HSP90 组织蛋白 (HOP) 在胃癌组织中的表达水平显着高于正常组织。此外，胃癌患者血清中HOP 的血清水平也更高。胃癌细胞自分泌的HOP通过PLCγ1和ERK1/2抑制细胞凋亡，并且可以增强胃癌细胞化疗抵抗。我们的研究结果表明，HOP 是胃癌重要的分子标志物和预后影响因素，未来有望成为胃癌的治疗新靶点。此外，我们还证明幽门螺杆菌通过CXCR2的介导促进胃黏膜上皮细胞衰老。幽门螺杆菌感染不仅上调了CXCR2，CXCL1，CXCL8，并且直接通过NFKB1直接结合CXCR2的启动子调控其表达。此外，CXCR2 形成了一个与 p53 的正反馈回路促进细胞衰老，阐明了幽门螺杆菌通过促进细胞衰老诱导胃癌发生的新机制。