Integrative transcriptomic and single-cell analysis reveals IL27RA as a key immune regulator and therapeutic indicator in breast cancer.

BACKGROUND: Interleukin-27 receptor alpha (IL27RA), a key subunit of the interleukin-27 receptor, plays an essential role in T cell-mediated immunity. However, its relevance in breast cancer and response to immunotherapy remains unexplored. METHODS: We integrated bulk and single-cell RNA sequencing data from TCGA, GEO, and scRNA-seq datasets to analyze IL27RA expression, prognosis, immune infiltration, and treatment response. TIDE and immune checkpoint-treated clinical cohorts were used to assess immunotherapy responsiveness. Chemotherapy sensitivity was predicted using GDSC data, and IL27RA protein expression was validated by Western blot. RESULTS: IL27RA was downregulated in breast cancer but high expression correlated with favorable survival. It was primarily expressed in T cells, particularly CD8⁺ subsets, and associated with enriched immune infiltration and elevated checkpoint gene expression. IL27RA high-expression patients showed lower TIDE scores, better outcomes in ICI-treated cohorts, and higher sensitivity to multiple chemotherapeutic agents. CONCLUSION: IL27RA is a potential immune biomarker that reflects an inflamed tumor microenvironment and predicts benefit from immunotherapy and chemotherapy in breast cancer. These findings provide novel insights into immune-based stratification using single-cell transcriptomic data.