Miao Fang, Lou Zhiguo, Ji Shuhua, Wang Dan, Sun Yaolan, Liu Huan, Yang Chenggang
School of Basic Medical Sciences, Shandong First Medical University, Jinan, China.
Department of General Education, Shandong First Medical University, Jinan, China.
Front Oncol. 2021 Sep 20;11:682814. doi: 10.3389/fonc.2021.682814. eCollection 2021.
Abnormal CLEC9A expression is concerned with carcinogenesis. However, the role of CLEC9A in lung adenocarcinoma (LUAD) remains unknown. The goal of this study was to reveal the role of CLEC9A in LUAD based on bioinformatics and cellular functional experiments.
Data available from The Cancer Genome Atlas (TCGA) were employed to study CLEC9A expression and mutations in LUAD. Expression and alterations of CLEC9A were analyzed using UALCAN and cBioPortal, respectively. Kaplan-Meier analysis was used to analyze the effect of CLEC9A on the survival of LUAD. Protein-protein interaction (PPI) network was built using GeneMANIA analysis. The similar genes of CLEC9A were obtained using GEPIA analysis, while co-expression genes correlated with CLEC9A were identified using LinkedOmics analysis. The effects of CLEC9A expression on immune cell infiltration was assessed. The effect of CLEC9A on the proliferation, apoptosis, cell cycle distribution, and invasion of human LUAD cells was detected in the LUAD cell line.
CLEC9A was downregulated and the CLEC9A gene was often altered in LUAD. The survival of LUAD patients was correlated with the expression level of CLEC9A. The similar genes of CLEC9A were linked to functional networks involving positive regulation of interleukin-12 production, plasma membrane and CD40 receptor binding, primary immunodeficiency, intestinal immune network for IgA production, and cell adhesion molecules pathways. Cell cycle, apoptosis, EMT, and RAS/MAPK were significantly enriched pathways in positive and negative correlation genes with CLEC9A. A difference in the immune infiltration level of immune cell between the high and low CLEC9A expression groups was observed. Somatic cell copy number alternations (CNAs) of the CLEC9A, including arm-level gain and arm-level deletion, observably changed the infiltration levels of B cells, CD4+ T cells, macrophages, and neutrophils in LUAD. Except for LAG3, the expression of CD274, CTLA4, PDCD1, and TIGIT was positively correlated with the expression level of CLEC9A. After transfection, overexpression and knockdown of CLEC9A could affect the proliferation, apoptosis, cell cycle distribution, and invasion of LUAD cells.
CLEC9A is associated with prognosis and tumor immune microenvironment of LUAD, suggesting that CLEC9A may be considered as a novel biomarker for LUAD.
CLEC9A表达异常与肿瘤发生有关。然而，CLEC9A在肺腺癌（LUAD）中的作用尚不清楚。本研究的目的是基于生物信息学和细胞功能实验揭示CLEC9A在LUAD中的作用。
利用来自癌症基因组图谱（TCGA）的数据研究LUAD中CLEC9A的表达和突变情况。分别使用UALCAN和cBioPortal分析CLEC9A的表达和改变情况。采用Kaplan-Meier分析来分析CLEC9A对LUAD患者生存的影响。利用GeneMANIA分析构建蛋白质-蛋白质相互作用（PPI）网络。使用GEPIA分析获得CLEC9A的相似基因，同时使用LinkedOmics分析鉴定与CLEC9A相关的共表达基因。评估CLEC9A表达对免疫细胞浸润的影响。在LUAD细胞系中检测CLEC9A对人LUAD细胞增殖、凋亡、细胞周期分布和侵袭的影响。
CLEC9A在LUAD中表达下调，且CLEC9A基因常发生改变。LUAD患者的生存与CLEC9A的表达水平相关。CLEC9A的相似基因与涉及白细胞介素-12产生的正调控、质膜和CD40受体结合、原发性免疫缺陷、IgA产生的肠道免疫网络以及细胞粘附分子途径的功能网络相关联。细胞周期、凋亡、上皮-间质转化（EMT）和RAS/丝裂原活化蛋白激酶（MAPK）是与CLEC9A呈正相关和负相关基因中显著富集的途径。观察到CLEC9A高表达组和低表达组之间免疫细胞的免疫浸润水平存在差异。CLEC9A的体细胞拷贝数改变（CNAs），包括臂水平的扩增和缺失，明显改变了LUAD中B细胞、CD4 + T细胞、巨噬细胞和中性粒细胞的浸润水平。除淋巴细胞活化基因3（LAG3）外，程序性死亡蛋白配体1（CD274）、细胞毒性T淋巴细胞相关蛋白4（CTLA4）、程序性死亡蛋白1（PDCD1）和T细胞免疫球蛋白和粘蛋白结构域蛋白3（TIGIT）的表达与CLEC9A的表达水平呈正相关。转染后，CLEC9A的过表达和敲低可影响LUAD细胞的增殖、凋亡、细胞周期分布和侵袭。
CLEC9A与LUAD的预后和肿瘤免疫微环境相关，提示CLEC9A可被视为LUAD的一种新型生物标志物。
