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.