The Expression and Prognostic Value of CCL19 in Breast Cancer

Abstract Background Breast cancer is the leading cause of cancer related death in women worldwide. Early diagnosis is the most effective way to reduce breast cancer mortality. Immune and tumor processes are closely related. This study aims to explore the mechanism of immune and potential biomarkers of breast cancer through bioinformatics. Objective First, differentially expressed genes (DEGs) were screened by consensus analysis of invasive breast cancer (BRCA) samples from The Cancer Genome Atlas (TCGA) database based on immune genes. Then, protein interaction (PPI) networks, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were used to narrow down the potential genes. Finally, expression analysis and prognostic analysis of hub genes were used to select reliable key genes to identify CCL19. Immunohistochemistry (IHC) was used to detect the differential expression of CCL19 in tumor tissues and adjacent tissues of breast cancer. Protein correlation analysis, signaling pathway analysis, immune infiltration analysis, gene co-expression analysis and drug sensitivity analysis of CCL19 were further used to explore the pathological clinical features and potential biological functions of CCL19. Results The expression of CCL19 was significantly increased in breast cancer. High expression of CCL19 correlates with tumor stage and predicts a better prognosis in breast cancer. The expression of CCL19 correlates with the levels of various tumor immune infiltrating cells (TILs). CCL19 has positive correlation with the expression of most immune-related genes, including immune activator, immunosuppressant, chemokine, chemokine receptor, and major histocompatibility complex (MHC) genes. Enrichment analysis showed that CCL19 was involved in immune-related pathways and PI3K-Akt signaling pathway. The above results indicate that CCL19 may modulate the prognosis of breast cancer through immune infiltration. CCL19 affects the sensitivity to chemotherapy and targeted therapy, which affects the sensitivity of TAK-715, KIN001-102 and 17-AAG. Conclusion CCL19 is overexpressed in breast cancer. CCL19 may serve as a promising biomarker for predicting breast prognosis and a candidate therapeutic target.