胃癌是一种消化道癌症，具有较高的患病率和死亡率，严重影响全球健康负担。对免疫系统功能的更多研究将改善胃癌患者的治疗和生存。我们尝试通过生物信息学分析方法，确定胃癌的潜在生物标志物或靶点。从基因表达杂志数据库获取了三个胃组织样本的基因表达剖面数据集（GSE79973、GSE103236和GSE118916）。从三个微阵列中鉴定出了65个重叠的差异表达基因（DEGs）。对DEGs的关键功能和通路进行了基因本体论和Kyoto基因和基因组百科全书通路分析。然后，通过蛋白质相互作用网络鉴定了十个中心基因。此外，我们观察到胶原Vα2（COL5A2）与胃癌预后以及M2型巨噬细胞浸润有关。此外，COL5A2通过PI3K-AKT信号通路促进胃癌细胞增殖并极化M2型巨噬细胞。因此，在本研究中，我们发现COL5A2与胃癌的发展有关，可能成为该疾病的潜在治疗靶点。

Gastric cancer is a type of digestive tract cancer with a high morbidity and mortality, which leads to a major health burden worldwide. More research into the functions of the immune system will improve therapy and survival in gastric cancer patients. We attempted to identify potential biomarkers or targets in gastric cancer via bioinformatical analysis approaches. Three gene expression profile datasets (GSE79973, GSE103236, and GSE118916) of gastric tissue samples were obtained from the Gene Expression Omnibus database. There were 65 overlapping differentially expressed genes (DEGs) identified from three microarrays. Gene ontology and Kyoto Encyclopedia of Genes and Genomes pathway were carried out for the key functions and pathways enriched in the DEGs. Then, ten hub genes were identified by protein-protein interaction network. In addition, we observed that collagen type V alpha 2 (COL5A2) was linked to gastric cancer prognosis as well as M2 macrophage infiltration. Furthermore, COL5A2 enhanced gastric cancer cell proliferation through the PI3K-AKT signaling pathway and polarized M2 macrophage cells. Therefore, in this study, we found that COL5A2 was associated with the development of gastric cancer which might function as a potential therapeutic target for the disease.