背景:脂质运载蛋白2(LCN2)是一种分泌的糖蛋白,在肿瘤发生和发展中起关键作用。有趣的是,LCN2在发展中的肺腺癌(LUAD)中似乎具有矛盾的功能。因此,我们拟通过生物信息学和实验验证,探讨LCN2在LUAD中的作用.
方法:在TCGA中研究LUAD的LCN2表达,TIMER和HPA数据库。通过KM绘图仪研究LCN2与预后的关系,TCGA和GEO数据库。GO,进行KEGG和蛋白质-蛋白质相互作用网络分析以探讨LCN2的潜在机制。在TCGA和TIMER数据库中研究了LCN2与癌症免疫浸润的相关性。定量逆转录PCR,采用westernblot和酶联免疫吸附试验鉴定LCN2在细胞和血清中的表达水平。CCK-8,伤口愈合和transwell试验用于证实LCN2对细胞增殖的影响,LUAD的迁移和入侵。利用受试者工作特征曲线进一步评估LCN2的诊断效率。
结果:LCN2在LUAD中表达明显上调(P<0.05),并与临床分期相关,肿瘤大小,淋巴结转移和远处转移(P<0.05)。高LCN2与LUAD患者预后差之间存在高度相关性。功能网络分析提示LCN2与多种信号通路在癌症中的作用有关。比如JAK-STAT,TNF,NF-κB,HIF-1和PI3K-Akt信号通路。此外,LCN2的敲除显著抑制细胞增殖能力,移民和入侵。免疫浸润分析表明LCN2与多种免疫细胞浸润有关。值得注意的是,LCN2对LUAD具有较高的诊断效能(AUC=0.818,P<0.05),尤其是III-IV期患者可达到0.895。
结论:LCN2作为一种致癌糖蛋白促进与免疫浸润有关的癌症进展,这可能是LUAD的潜在诊断和预后标志物。
BACKGROUND: lipocalin 2 (LCN2) is a secreted glycoprotein that plays key roles in tumorigenesis and progression. Interestingly, LCN2 appears to have a contradictory function in developing lung adenocarcinoma (LUAD). Thus, we intend to explore the role of LCN2 in LUAD through bioinformatics and experimental validation.
METHODS: LCN2 expression of LUAD was investigated in the TCGA, TIMER and HPA databases. The relationship between LCN2 and prognosis was investigated by KM plotter, TCGA and GEO databases. GO, KEGG and protein-protein interactions network analysis were conducted to investigate the potential mechanism of LCN2. The relevance of LCN2 to cancer-immune infiltrates was investigated in the TCGA and TIMER databases. Quantitative reverse transcription PCR, western blot and enzyme-linked immunosorbent assay were performed to identify the expression level of LCN2 in cells and serum samples. The CCK-8, wound healing and transwell assay were used to confirm the effect of LCN2 on cell proliferation, migration and invasion in LUAD. The receiver operating characteristic curve was utilized to assess the diagnostic efficiency of LCN2 further.
RESULTS: LCN2 expression was significantly upregulated in LUAD (P < 0.05), and was correlated with the clinical stage, tumor size, lymph node metastasis and distant metastasis (P < 0.05). There was a high correlation between high LCN2 and worse prognosis in LUAD. Functional network analysis suggested that LCN2 was associated with multiple signal pathways in cancers, such as JAK-STAT, TNF, NF-κB, HIF-1 and PI3K-Akt signal pathways. In addition, the knockdown of LCN2 significantly inhibited the ability of cell proliferation, migration and invasion. Immune infiltration analysis indicated that LCN2 is associated with multiple immune cell infiltration. Notably, LCN2 demonstrated high diagnostic efficiency for LUAD (AUC = 0.818, P < 0.05), especially for stage III-IV patients could reach 0.895.
CONCLUSIONS: LCN2 as an oncogenic glycoprotein promotes the cancer progression related to immune infiltrates, which might be a potential diagnostic and prognostic marker in LUAD.