基于多数据库分析SCN7A在肺腺癌中的表达及意义

Expression and Significance of SCN7A in Lung Adenocarcinoma Based on Multi-Database Analysis

摘要: 目的：通过生物信息学的方法分析电压门控钠通道α亚基7 (Sodium Voltage-Gated Channel Alpha Subunit 7, SCN7A)基因在肺腺癌(lung adenocarcinoma, LUAD)和邻近非癌组织中的差异表达，探讨其与肺腺癌患者临床病理特征和预后的相关性，分析其可能调控的信号通路和在肿瘤免疫微环境中的作用，并通过细胞实验验证SCN7A在肺腺癌细胞中的生物学功能。方法：从癌症基因组图谱(The Cancer Genome Atlas, TCGA)数据库和基因型组织表达(Genotype-Tissue Expression, GTEx)数据库下载并整理33种肿瘤患者的基因表达数据进行SCN7A泛癌分析。利用TCGA数据库探讨SCN7A基因在肺腺癌及正常肺组织中的表达差异情况，并使用临床样本qRT-PCR对结果进行验证。ROC曲线评估SCN7A的诊断价值。从人类蛋白质图谱(The Human Protein Atlas, HPA)数据库下载LUAD患者及健康人群免疫组织化学数据。Cox回归分析寻找LUAD独立预后因素。临床相关性分析揭示SCN7A与LUAD患者临床病理特征的相关性。采用Kaplan-Meier Plotter数据库进行生存分析。通过功能注释工具分析SCN7A及其互作基因的功能。通过肿瘤免疫系统相互作用数据库(Tumor Immune System Interaction Database, TISIDB)分析SCN7A与肺癌肿瘤免疫浸润之间的关系。体外培养人正常肺上皮细胞BEAS-2B、肺腺癌细胞A549、H1395、H1975，qRT-PCR检测以上4株细胞中SCN7A的表达。构建SNC7A过表达质粒，转染至A549细胞中。采用cell counting kit8 (CCK8)、划痕试验、Transwell方法检测SCN7A基因过表达对肺腺癌A549细胞增殖、迁移及侵袭的影响。结果：SCN7A在肺腺癌中的表达显著低于正常肺组织(P < 0.001)，并与T分期、病理分级、总生存期(OS)等临床病理特征呈负相关(P < 0.05)。Cox回归分析发现SCN7A低表达是影响LUAD预后的独立危险因素(P < 0.05)。SCN7A低表达的肺腺癌患者总生存期、首次进展时间显著缩短(P < 0.001)。功能富集分析提示SCN7A主要参与E2f targets、G2m checkpoint等相关通路(P < 0.001)。免疫浸润分析显示SCN7A表达水平与LUAD中肥大细胞(Mast cell)、树突状细胞(DC)、巨噬细胞(Macrophages)、滤泡辅助性T细胞(TFH)浸润丰度相关(P < 0.001)。SCN7A在A549、H1395、H1975细胞中表达显著低于BEAS-2B细胞。过表达SCN7A后，A549细胞增殖、迁移和侵袭能力显著降低(P < 0.01)。结论：SCN7A低水平表达与LUAD患者的不良预后和免疫细胞浸润状况密切相关，其有望被确立为一种用于LUAD诊断和治疗的新型生物标志物。

Abstract: Objective: This study aimed to analyze the expression differences of Sodium Voltage-Gated Channel Alpha Subunit 7 (SCN7A) in lung adenocarcinoma (LUAD) and adjacent non-tumor tissues, investigating its correlation with the clinical pathological characteristics and outcomes of LUAD patients. It also analyzes the potential signaling pathways regulated by SCN7A and its role in the tumor immune microenvironment. The biological function of SCN7A in lung adenocarcinoma cells was investigated by cell experiments. Methods: Gene expression profiles of 33 tumor types were downloaded from the Human Protein Atlas (TCGA) database and Genotype-Tissue Expression (GTEx) databases for pan-cancer analysis of SCN7A. The expression difference of SCN7A gene in lung adenocarcinoma and adjacent normal tissues was investigated by using TCGA database, and the results were verified by qRT-PCR of clinical samples. ROC curve was employed to evaluate the diagnostic value of SCN7A. The immunohistochemical data of LUAD patients and healthy individuals were obtained from the Human Protein Atlas (HPA) database. Cox regression analysis was conducted to identify the independent prognostic factors. Clinical correlation analysis revealed the correlation between SCN7A and clinicopathological features of LUAD patients. Kaplan-Meier Plotter database was used for survival analysis. The function of SCN7A and its interacting genes was analyzed by functional annotation tools. The relationship between SCN7A and tumor immune infiltration in lung adenocarcinoma was analyzed through the Tumor Immune System Interaction Database (TISIDB). Human normal lung epithelial cells BEAS-2B, lung adenocarcinoma cells A549, H1395, H1975 were cultured in vitro. The expression of SCN7A in the above 4 cell lines was detected by qRT-PCR. SCN7A overexpression plasmid was constructed and transfected into A549 cells. The effects of SCN7A overexpression on the proliferation, migration and invasion of A549 cells were detected by Cell counting kit 8 (CCK8), scratch test and Transwell methods. Results: The expression of SCN7A in lung adenocarcinoma was significantly lower than in adjacent normal lung tissues (P < 0.001), and was negatively correlated with T stage, pathological grade, and overall survival (OS) (P < 0.05). Cox regression analysis revealed that low SCN7A expression was an independent risk factor for the prognosis of LUAD (P < 0.05). Patients with low SCN7A expression had a significantly reduced overall survival (OS) time and first progression (FP) time (P < 0.001). Function enrichment analysis suggested that SCN7A mainly participates in E2f targets, G2m checkpoint, etc. related pathways. Immune infiltration analysis showed that SCN7A expression correlated with mast cell, dendritic cell, macrophage, and follicular helper T cell infiltration in LUAD. The expression of SCN7A in A549, H1395 and H1975 cells was significantly lower than in BEAS-2B cells. After overexpression of SCN7A, proliferation, migration and invasion of A549 cells were significantly decreased (P < 0.01). Conclusion: The low expression level of the SCN7A gene is closely associated with poor prognosis and immune cell infiltration in lung adenocarcinoma patients, suggesting its potential to be established as a novel biomarker for the diagnosis and treatment of lung adenocarcinoma.