Background: Lung cancer is the most common malignant tumor in China, lung adenocarcinoma (LUAD) is the main type of lung cancer, which is a serious threat to people's life and health. At present, there are fewer studies on the role of Dikkopf1 (DKK1) in lung adenocarcinoma. The aim of this study was to investigate the role and potential prognostic value of DKK1 in the development of lung adenocarcinoma by bioinformatics methods.
Methods: Several databases, such as genotype-tissue expression (GTEx), The Cancer Genome Atlas (TCGA) and tumor-immune system interactions database (TISIDB), were used to analyze the expression, clinicopathological features, immune cell infiltration, prognosis and methylation of DKK1 in lung adenocarcinoma. Then, linked immune cell infiltration Omics database was used to analyze the co-expressed genes of DKK1 and their functional enrichment. Finally, 59 pathological samples of paraffin-embedded lung adenocarcinoma patients who underwent surgery at the Affiliated Cancer Hospital of Xinjiang Medical University between 2016 and 2017 were collected for the validation of the prognostic value of expression by immunohistochemistry (IHC) test.
Results: The results of bioconfidence analysis showed that the expression level of DKK1 in lung adenocarcinoma tissues was higher than that in normal tissues, the expression in advanced cancers was higher than that in early stages, and the experimental validation revealed that among 59 cases of lung adenocarcinoma, there were 15 cases of negative expression (25.4%), 18 cases of weakly positive expression (30.5%), and 26 cases of strongly positive expression (44.1%). The different expression of DKK1 is related to methylation, prognosis and the activities of various immune cells. Functional enrichment shows that DKK1 may be involved in skin development and cell-substrate junction, and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis shows that DKK1 is related to ABC transporters. Bioinformatics analysis and clinical case specimens showed that high DKK1 expression was associated with poorer prognosis in patients with lung adenocarcinoma.
Conclusions: High expression of DKK1 in lung adenocarcinoma is associated with poor prognosis. DKK1 is closely associated with tumor immune cell infiltration and pathways. DKK1 can be considered as a potential prognostic marker and a novel target for immunotherapy of lung adenocarcinoma.
【中文题目：基于生物信息学探索DKK1在肺腺癌发生中的作用】 【中文摘要：背景与目的 肺癌是我国最常见的恶性肿瘤，肺腺癌（lung adenocarcinoma, LUAD）是肺癌的主要类型，严重威胁着人民的生命健康，目前关于血清分泌型蛋白1（Dikkopf 1, DKK1）在LUAD中的作用研究较少，本研究旨在通过生物信息学方法探究DKK1在LUAD发生发展中的作用及潜在的预后价值。方法 应用基因型组织表达（genotype-tissue expression, GTEx）、癌症基因组图谱（The Cancer Genome Atlas, TCGA）数据库和肿瘤与免疫系统交互网站（tumor-immune system interactions database, TISIDB）等多个数据库，对DKK1在LUAD中的表达、临床病理特征、免疫细胞浸润、预后和甲基化等进行分析，同时应用LinkedOmics数据库分析DKK1的共表达基因及其功能富集。收集2016年至2017年于新疆医科大学附属肿瘤医院行手术治疗的59例石蜡包埋的LUAD患者病理样本，通过免疫组织化学试验（immunohistochemistry, IHC）进行表达预后验证。结果 生信分析结果显示DKK1在LUAD组织的表达水平高于正常组织，晚期癌症中的表达高于早期阶段，实验验证后发现59例LUAD中阴性表达15例（25.4%），弱阳性表达18例（30.5%），强阳性表达26例（44.1%）。DKK1的不同表达情况与甲基化、预后以及多种免疫细胞的活动相关。功能富集显示DKK1可能参与表皮发育、细胞-基质连接等过程，京都基因与基因组百科全书（Kyoto Encyclopedia of Genes and Genomes, KEGG）分析表明DKK1与ABC转运蛋白相关。生物信息学分析及临床病例标本显示DKK1高表达与LUAD患者较差的预后有关。结论 DKK1在LUAD中高表达，与患者预后不良有关，并且DKK1与肿瘤免疫细胞浸润和通路密切相关。DKK1可能是LUAD潜在的预后标志物和免疫治疗新靶点。 】 【中文关键词：肺肿瘤；DKK1；预后】.
Keywords: DKK1; Lung neoplasms; Prognosis.