Integrated Bioinformatics Analysis Found That Immune-related Gene C5AR1 May Be A Potential Prognostic Marker Of Glioma

Objective: Immune-related genes play an important role in tumor development,so our study aimed to discover immune-related genes associated with the prognosis of glioma patients and to explore the infiltration of immune cells in the tumor microenvironment of glioma associated with immune-related genes.Methods: First,the expression profiles(m RNAseq)data of glioma samples from the Chinese Glioma Genome Atlas(CGGA)database were downloaded,which needed to be normalized and batch corrected because they were divided into two batches.Then the primary glioma samples among them were selected for subsequent analysis.Next,the stromal score and immune score of the primary glioma samples were analyzed differentially using the ESTIMATE algorithm,and then the differentially expressed genes of the stromal score and immune score were intersected with the immune genes in the Immport database to obtain the common Immune Related Genes(IRGs),which were then subjected to functional enrichment analysis.In addition,we used the IRGs to construct a Protein-Protein Interaction(PPI)network and screened the top 30 genes with high degree of connectivity(Degree)from them.We screened the top 30 genes with the highest degree of connectivity in the PPI through the Pubmed database,and screened IRGs that have not been studied in depth in glioma,and performed differential expression analysis,survival analysis,association with tumor stage,Gene Set Enrichment Analysis(GSEA)of single genes,independent Prognostic factor analysis,Receiver Operating Characteristic(ROC)curve to predict the sensitivity and specificity of target genes,and other bioinformatics analyses.In addition,we performed immune-related pathway and Hallmark and Kyoto Encyclopedia of Genes and Genomes(KEGG)pathway enrichment analyses on target genes.Finally,we used the CIBERSORT algorithm to estimate the expression matrix of primary gliomas for 22 immune cell contents and analyzed the relationship between target gene expression and immune cells,as well as the correlation analysis between target genes and immune cells.Importantly,we also performed a survival analysis of immune cells.Results: A total of 915 differentially expressed genes(695 up-regulated genes and 220 down-regulated genes)were found in the stromal score;991differentially expressed genes(614 up-regulated genes and 377 down-regulated genes)were found in the immune score;then the above differential genes were intersected together with the Immport immune database,resulting in a total of118 IRGs.after Pub Med screening of PPI linkage degree of the top 30 genes,we found that only the C5AR1 gene was not studied in depth in glioma.Therefore,we selected C5AR1 gene for follow-up analysis.Integrative bioinformatics study revealed that C5AR1 gene was differentially expressed in low-grade glioma,glioblastoma and normal brain tissue(P<0.05).The results of survival analysis showed that the C5AR1 gene significantly reduced the overall survival of patients with low-grade glioma(WHO grade II)and high-grade glioma(WHO grade III and WHO grade IV)(P<0.05).Moreover,the expression of C5AR1 gene was proportional to the grade of glioma,and the gene expression increased with the increase of tumor grade(P<0.05).Single gene GSEA analysis revealed that C5AR1 gene was mainly enriched in Hallmark pathway in multiple pathways related to glioma development and progression,such as P53 pathway(P53 pathway),PI3K/AKT/MTOR signaling(PI3K/AKT/MTOR signaling pathway),Angiogenesis(angiogenesis generation pathway),etc.The KEGG pathway is mainly enriched in VEGF signaling pathway(VEGF signaling pathway),P53 signaling pathway(P53 signaling pathway),Pathways In Cancer(cancer pathway signaling pathway),JAK/STAT signaling pathway(JAK/STAT signaling pathway),etc.Independent prognostic analysis showed that C5AR1 gene could be an independent prognostic factor for glioma(P<0.05),and the area under the curve(AUC)of ROC curve was 0.71,which also supported that it could be a target gene and therapeutic target for glioma.In addition,tumor microenvironment analysis revealed that the expression of target genes was associated with neutrophil(P<0.05).Importantly,correlation analysis also suggested that target gene expression was associated with neutrophils(P<0.05),and survival analysis showed that high expression of target genes significantly reduced the overall survival of glioma patients(P<0.05).Conclusion: Integrative bioinformatics analysis revealed that C5AR1 gene was differentially expressed in normal brain tissue and primary glioma and was associated with the staging of primary glioma and the overall survival of primary glioma patients.In addition,high expression of C5AR1 gene is also involved in the development and progression of primary glioma through multiple biological pathways.And it can also be used as an independent prognostic factor in primary glioma disease to assess the prognosis of primary glioma patients.Analysis of the immune microenvironment of primary glioma revealed that C5AR1 gene expression is associated with neutrophils(Neutrophil)and that the higher the expression of Neutrophil in primary glioma patients,the lower the overall survival rate of patients.