Expression of the prognostic marker IL-8 correlates with the immune signature and epithelial-mesenchymal transition in breast cancer.

BACKGROUND: IL-8 has been implicated in the malignant progression of various types of cancers; however, the precise molecular mechanisms associated with IL-8 in breast cancer (BRCA) are unclear. METHODS: We analyzed the clinical signature and immune characteristics of BRCA patients and its correlation with IL-8 expression using The Cancer Genome Atlas (TCGA) datasets. The role of IL-8 in epithelial-mesenchymal transition (EMT) was verified through Western blotting, Cell Counting Kit-8 assay, and wound healing assays, as well as cell invasion experiments. RESULTS: Through a comprehensive bioinformatics study, we determined that high IL-8 expression was associated with poor prognosis. Enrichment analysis revealed that high IL-8 expression was enriched in immune-related processes and cancer-related signaling pathways. In addition, IL-8 was associated with most of the immune-infiltrating cells, and high IL-8 expression indicated poor response to immunotherapy. Importantly, we found that IL-8 induced EMT in vitro. CONCLUSIONS: Taken together, our data indicate that IL-8 may be a potential and valuable prognostic marker in BRCA, which may induce adverse outcomes by modulating the immune response and promoting EMT in BRCA patients.