胃癌临床病理分期相关基因MGP的发现及其表达验证

Discovery and verification of matrix gla protein, a TNM staging and prognosis-related biomarker for gastric cancer

目的通过对基因芯片数据库中一组大样本胃癌表达谱芯片的数据挖掘分析，筛选并验证与临床病理分期及预后密切相关的基因。方法检索基因表达谱芯片数据库，对其中符合分析要求（大样本、病理分型、临床病理分期以及随访资料齐全）的胃癌表达谱芯片数据进行再挖掘分析。利用基因芯片显著性差异基因分析（SAM）方法筛选出不同临床病理分期的差异基因，并通过逆转录聚合酶链反应（RT—PCR）、即时荧光定量PCR、Westernblot方法验证胃癌细胞株及54例胃癌组织MGP表达，利用免疫组织化学EnVision法观察MGP在胃癌中的定位特点。结果通过对GEO开放数据库内GES4007数据的挖掘分析，发现14个基因表达与胃癌临床病理分期显著相关，其中MGP基因表达升高与临床病理分期呈正相关，对预后有明显影响。定量PCR和Westernblot方法证实MGP在胃癌细胞系中存在不同程度表达，免疫组织化学染色显示MGP定位于肿瘤细胞胞质内。RT．PCR分析54例胃癌组织和对应癌旁组织内mRNA，结果显示22例癌组织MGP的mRNA表达明显高于癌旁组织（40．7％）。MGP的高表达与胃癌临床病理分期（P=0．001）和预后呈明显相关（P=0．006）。结论公共数据库存储的芯片数据具有再分析价值。MGP基因是与胃癌临床病理分期和预后相关的新型分子标志物。

Objective To analyze microarray datasets deposited in the public database and to identify TNM associated genes in gastric cancers. Methods Microarray datasets of gastric cancer were selected from GEO database. Differentially expressed genes related to TNM staging were evaluated by significant analysis of the microarray using MuhiExperiment Viewer （MEV） platform. Candidate gene expressions in gastric cancer tissues and cell lines were verified by reverse transcrlptase polymerase chain reaction（RT-PCR）, quantitative RT-PCR, Western blot and immunohistochemistry. Results GES4007 dataset was re-analyzed leading to the identification of 14 genes associated with TNM staging. Over- expression of matrix gla protein （MGP） was confirmed in gastric cancer cell lines and tumor tissues by quantitative RT-PCR, Western blot and immunohistochemistry. Increased MGP expression was found in 22 of 54 cases of （40. 7% ） gastric cancer specimens compared to the normal gastric tissues. The up-regulation of MGP mRNA expression closely correlated with TNM stage （ P = 0. 001 ） and prognosis （ P = 0. 006 ）. Conclusions Public databases of microarray studies are the valuable resources for data mining. MGP has been identified and confirmed as a novel biomarker for the TNM stage and prognosis of gastric cancer.