ECRG4在胃癌上皮间质转化中的作用及分子机制研究

Epithelial-mesenchymal transition (EMT) is crucial for metastasis initiation of gastric cancer, but the underlying molecular mechanisms remains to be elucidated. We have demonstrated that esophageal carcinoma related gene 4 (ECRG4) could serve as a candidate tumor suppressor gene. Our latest results show that ① ECRG4 protein expression was significantly decreased in metastatic gastric cancer tissues; ② silencing of ECRG4 promoted malignant invasiveness of gastric cancer cells; and ③ the expression of EMT-related proteins were closely associated with ECRG4. Based on these results, we hypothesize that ECRG4 may regulate EMT and metastasis initiation of gastric cancer. Thus, we are going to investigate the molecular mechanism of ECRG4 on gastric cancer metastasis by ① testing the effect of ECRG4 to regulate metastasis initiation steps using in intro cell culture experiments; ② evaluating whether ECRG4 is a switch to control gastric cancer metastasis using tumor metastasis models in nude mice and in vivo fluorescence imaging technology; ③ exploring the potential molecular mechanism of ECRG4 to regulate EMT and metastasis initiation of gastric cancer; and ④ examining clinical specimens to illustrate the potential relationship between ECRG4 expression and cancer metastasis and patient prognosis. The present project aims to a better understanding of the functions and molecular mechanism of ECRG4 on EMT and metastasis initiation of gastric cancer, which may lead to new diagnostic, therapeutic and preventive strategies to this disease.

上皮间质转化（EMT）在胃癌转移起始过程中发挥着重要的作用，其具体分子机制仍有待充分阐明。课题组研究证实食管癌相关基因4（ECRG4）是潜在的抑癌基因。前期工作表明：①在已有转移的胃癌组织中ECRG4表达显著降低；②沉默ECRG4增强胃癌细胞恶性侵袭能力；③ECRG4与EMT关键蛋白表达密切相关。我们推测ECRG4是调控胃癌EMT和转移起始的重要基因。为了验证我们的假说，本课题拟对以下内容进行研究：①应用体外细胞实验明确ECRG4对转移起始关键步骤的调节；②活体成像技术结合裸鼠转移模型，在体验证ECRG4是控制胃癌转移的开关；③证实通过ECRG4调节EMT和转移起始的分子机制；④检查临床标本，分析ECRG4表达与胃癌转移和预后的关系。本课题针对胃癌转移的起始环节，探讨ECRG4对胃癌转移的作用与分子机制，对于揭示胃癌转移的调控机理和设计新的药物靶点具有重要意义。

食管癌相关基因4（ECRG4）是胃癌潜在的抑癌基因。我们检测了ECRG4在胃癌组织cDNA芯片中的表达，发现是显著下调的。分析其表达与临床病理参数、预后的关系；构建ECRG4过表达载体，并检测ECRG4过表达质粒在细胞中的过表达效率。筛选Snail作为ECRG4的下游调控基因，进行进一步的验证。我们将ECRG4在AGS细胞中过表达，然后进行转录组测序。根据测序的差异基因数据，结合文献查询，筛选2个表达上调且有文献报道为抑癌基因的上调差异基因进行表达验证。首先在ECRG4过表达的AGS样本中进行验证，发现目标基因上调更显著。然后在胃癌组织芯片中进行大样本验证，发现目标基因在胃癌样本中显著低表达，目前，我们得到的结论：在胃癌中ECRG4异常低表达。免疫组化中ECRG4胞核阳性是胃癌患者预后的独立预测因子。过表达ECRG4能够降低下调Snail，能够增强下游目标基因的转录活性，从而发挥抑癌作用。进一步说明了ECRG4是调控胃癌EMT和转移起始的重要基因。