Impact of Biomarkers Associated with CD8+ T cells in Idiopathic Pulmonary Fibrosis on LUSC Immune Infiltration and Construction of CeRNA

Abstract

Abstract Background: Idiopathic pulmonary fibrosis (IPF) has an insidious onset, no apparent symptoms in the early stage, and is easily combined with lung cancer in the late stage with a poor prognosis. Previous studies have found an overlap between the pathogenesis of IPF and lung cancer (LC), and immune infiltration plays an essential role in the development. But there are still no immune-related markers associated with IPF that have an impact on lung squamous cell carcinoma (LUSC) tumor infiltration. Methods: The IPF-related datasets GSE53845, GSE107797, and GSE110147 were acquired from the GEO database. WGCNA analyses of the GSE53845 dataset to identify the most relevant modules and candidate hub genes associated with CD8+ T cells. GO and KEGG analysis were performed on all genes within the module. Next, GSE107797 and GSE110147 were used to verify the relationship between candidate hub genes and CD8+ T cells to identify hub genes. The TIMER database was used to analyze the relationship between hub genes and CD8+ T cells in different cancers. UALCAN was used for the pan-cancer analysis of hub genes. And the mRNA expression levels, prognosis, and gene interrelationships of hub genes in LUSC i dentified by GEPIA, TIMER, TarBase v8, OncoLnc, and starBase to construct a ceRNA regulatory network. The role of hub gene expression in tumor immune infiltration was studied using the TIMER and GEPIA. Finally, we performed single-gene GSEA analysis of the hub genes, methylation analysis of the hub genes using the DiseaseMeth database, and protein expression analysis of the hub gene determined by the Human Protein Analysis (HPA) online database. Results: WGCNA identified the pink module as the most relevant module for CD8+ T cells and selected seven candidate hub genes. GO analysis and KEGG analysis further validated the IPF and immune correlation. Three hub genes (CCL5, CXorf65, and RASAL3) significantly associated with CD8+ T cells were validated and identified using the GSE107797 and GSE110147 datasets. Hub genes were positively associated with CD8+ T cells in various cancers. In the pan-cancer analysis, low expression of CXorf65 and RASAL3 was associated with poor prognosis in LUSC. In addition, we found that CXorf65 and RASAL3 were significantly and positively correlated with LUSC immune infiltration, immune cell biomarkers and immune checkpoint expression. We successfully constructed the ceRNA network of CXorf65 and RASAL3. CXorf65, RASAL3 methylation levels, and protein expression levels differed in LUSC and normal tissues. Single-gene GSEA analysis further confirmed the involvement of CXorf65 and RASAL3 in multiple immune responses. Conclusion: CXorf65 and RASAL3 were significantly associated with CD8+ T cells in IPF and play an impact on LUSC Immune infiltration.