Single-cell transcriptome reveals OCIAD2 expression in malignant epithelial cells of lung adenocarcinoma and its relationship with immune infiltration

Objective The aim of this study was to investigate OCIAD2 expression in malignant epithelial cells of lung adenocarcinoma (LUAD) and its correlation with immune infiltration by scRNA-seq.Methods scRNA-seq data GSE117570, transcriptome GSE118370 and GSE30219 datasets were downloaded from GEO database to screen for LUAD-related differentially expressed genes in epithelial cells, the proposed temporal sequencing analysis revealed the dynamic development and differentiation relationship of the cells, GO and KEGG enrichment analysis identified the main pathways involved, and CIBERSORT algorithm to analyze the correlation between LUAD and immune-infiltrating cells, construction of weighted gene co-expression network to identify modules related to LUAD, plotting of ROC feature curves to diagnose the value of key genes, and finally analysis of key diagnostic genes' functions by single-gene GSEA.Results The target gene OCIAD2 was highly expressed in LUAD malignant epithelial cells as screened by scRNA-seq and differential analysis, and ROC curves showed that OCIAD2 had good diagnostic ability, and its expression was significantly different between LUAD patients and healthy controls. OCIAD2 expression was significantly correlated with T cells, plasma cells, mast cells, B cells and macrophages, and GSEA enrichment analysis showed that OCIAD2 was involved in the P53 signaling pathway, Ras signaling pathway, cAMP signaling pathway and chemokine signaling pathway.Conclusions OCIAD2 was identified as a key gene for the diagnosis of LUAD, providing a theoretical basis for the diagnosis of LUAD.