Comprehensive analysis of STAT family members as prognostic markers in human breast cancer

Breast cancer has the highest morbidity and mortality among cancers in women owing to its malignancy, and its incidence increases with age. However, the specific mechanisms underlying breast cancer recurrence and metastasis remain poorly understood. Numerous tumors have shown extensive dependence on janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling. However, the STAT family has not yet been studied systematically in breast cancer. In this study, we investigated the expression differences, prognostic values, molecular functions, and immune infiltration of STAT members in breast cancer. For these analyses, we used The Cancer Genome Atlas (TCGA), cBioPortal, Kaplan-Meier plotter, and the TIMER databases. Significant changes were observed in the STAT expression in breast cancer, and higher expression levels of STAT1/3/4/5A/5B/6 were associated with a longer overall survival in breast cancer. Moreover, significant differences in STAT3, STAT5A, and STAT6 expression were observed at different tumor stages. Members of the STAT family and the associated genes were found to be involved in the regulation of various biological functions, such as "defense response to virus", "innate immune response", and "protein binding" in breast cancer. The expression levels of the STAT family members were positively associated with the infiltration of B cells, CD4+T cells, CD8+T cells, macrophages, dendritic cells, and neutrophils in breast cancer. Our results indicate that the expression of the members of the STAT family may be correlated with breast cancer progression and prognosis. Therefore, the STAT family can be used as a prognostic biomarker for confirming disease prognosis and immune infiltration levels in breast cancer.