as an Immune-Related Biomarker for Breast Cancer: A Study Based on Multiple Databases.

Objectives: To screen the target genes that are associated with survival of breast cancer (BRCA) and explore their prognostic values and immune correlations with BRCA using multiple databases..

Methods: The microarray expression datasets of BRCA were downloaded from the Gene Expresssion Omnibus database (GEO) and analyzed to obtain differentially expressed genes (DEGs). Hub genes were obtained by constructing and visualizing the protein-protein interaction network of DEGs. The key gene was determined using R language, STRING, and Cytoscape, and the differential expression of the key gene was verified using external datasets The Cancer Genome Atlas (TCGA) and quantitative real-time PCR (qRT-PCR) for BRCA tissues of 37 patients. The prognostic value and immunological correlation of in BRCA were explored using R language, TIMER, and Gene Set Enrichment Analysis (GSEA).

Results: Of 10 hub genes seleceed from 302 DEGS, was identified as the gene associated with BRCA survival. The expression of was differentially upregulated in BRCA, as verified by TCGA and qRT-PCR. Prognostic analysis revealed that served as an independent prognostic factor. High expression of was associated with decreased immune infiltration levels of B cells, CD4+ T cells, CD8+ T cells, macrophages, and myeloid dendritic cells in BRCA tissue. The expression of in BRCA showed a significant correlation with immune checkpoints genes , , and expressions. There was a positive correlation between the expression of and the tumor mutational burden and microsatellite instability. GSEA demonstrated that expression significantly enriched 786 immune-related gene sets.

Conclusions: expression in BRCA tissues is closely related to the BRCA immune microenvironment and showes predictive values on the survivals and prognosis of BRCA patients and the effecacy of immunotherapy. may be an potential immune-related prognostic biomarker for BRCA.