Identification Of PPIA As A Prognostic Biomarker Of Lung Adenocarcinoma From Bioinformatics Analysis

Background: We aim to investigate the expression of the peptidylprolyl isomerase A (PPIA) gene in lung adenocarcinoma(LUAD),and to investigate the diagnostic, prognostic value and correlation with immune infiltrates of PPIA in LUAD. Methods: : Transcriptional expression profiles of PPIA between LUAD tissues and normal tissues were downloaded from the Cancer Genome Atlas (TCGA).The PPIA protein expression was assessed by the Clinical Proteomic Tumor Analysis Consortium (CPTAC) .Receiver operating characteristic(ROC) curve was used to differentiate LUAD from adjacent normal tissues.Kaplan-Meier method was conducted to assess the effect of PPIA on survival.Protein-protein interaction (PPI) networks were constructed by the STRING.Functional enrichment analyses were performed using the“ClusterProfiler”package.The relationship between PPIA mRNA expression and immune infiltrates was determined by tumor immune estimation resource (TIMER) and tumor-immune system interaction database (TISIDB). Results: : The expression of PPIA in LUAD tissues was significantly upregulated than those in adjacent normal tissues. High PPIA mRNA expression was associated with lymph node metastases and high TNM stage. The ROC curve analysis showed that PPIA had an AUC value of 0.804(95% CI: 0.764-0.843).Kaplan-Meier survival analysis showed LUAD patients with high-PPIA had a worse prognosis than those with low-PPIA(mOS: 42.2months VS 87.2months,P＜0.001). Correlation analysis indicated PPIA mRNA expression was correlated with immune infiltrates.PPIA expression had correlations with CD4+ T cell (r = -0.29, P = 5.51e-11),macrophage M1 (r = 0.106, P = 1.84e-02), and B cell (r = -0.181, P =5.40e-5). Conclusion: Our research showed that PPIA could be used as a prognostic biomarker.Up-regulation of PPIA expression is significantly related to poor prognosis and immune infiltration of LUAD and may be a potential therapeutic molecular target for LUAD patients.