CXCL12, A Potential Biomarker and A Vital Modulator of Tumor Immune Microenvironment (TIME) of Bladder Cancer: From A Comprehensive Analysis of TCGA Database
Abstract Background: Tumor immune microenvironment (TIME) played a significant role in the initiation and progression of bladder cancer (BC). However, there are few researches regarding the association between immune-related genes (IRGs) and tumor-infiltrating immune cells (TICs) in TME of BC. Methods: We calculated the proportion of immune/stromal component and TICs in TME of 414 BC samples and 19 normal samples downloaded from The Cancer Genome Atlas (TCGA) database with the help of ESTIMATE and CIBERSORT algorithms. Differentially expressed genes (DEGs) were obtained from the comparison between Stromal and Immune Score and further analyzed by GO and KEGG enrichment analysis, as well as protein–protein interaction (PPI) network and COX regression analysis. CXC chemokine ligand-12 (CXCL12) was overlapping from the above analysis. Afterwards, single gene analysis of CXCL12 was carried out through difference analysis, paired analysis and Gene Set Enrichment Analysis (GSEA). The association between the expression of CXCL12 and TICs was assessed by difference analysis and correlation analysis.Results: The results indicated that immune and stromal component in TME of BC were associated with patients’ clinic-pathological characteristics. We further confirmed that 284 DEGs were primarily enriched in immune-associated activities and CXCL12 was the most significant gene, which shared the leading nodes in PPI network and closely related with BC patients’ survival. Single gene analysis revealed that CXCL12 was down-regulated in BC samples and significantly related with the clinic-pathological characteristics of patients. Further analysis indicated that CXCL12 greatly participated in immune-associated activities through closely communicating with TICs in TIME of BC.Conclusions: CXCL12 might be a potential biomarker and a vital modulator of TIME through communicating with multiple TICs, which might provide an extra insight for the immunotherapy of BC.