Abstract
Breast cancer remains a leading cause of cancer-related mortality among women, with triple-positive breast cancer (TPBC) being a particularly aggressive subtype. GATA binding protein 3 (GATA3) plays a crucial role in the luminal differentiation of breast epithelium and T-cell differentiation. However, the relationship between GATA3 and immune infiltration in TPBC remains unclear. This study collected and analyzed TPBC data from The Cancer Genome Atlas (TCGA), METABRIC, and GSE123845 databases. Univariate and multivariate Cox regression analyses, along with Kaplan-Meier survival analyses, were employed to assess the prognostic value of GATA3 and other clinical features. Subsequently, Gene Set Enrichment Analysis (GSEA) was conducted to explore the potential biological functions and regulatory mechanisms of GATA3 in TPBC. Additionally, ssGSEA analysis revealed the connection between GATA3 and immune infiltration. And the effects of neoadjuvant chemotherapy and immunotherapy on GATA3 expression were also explored. Finally, clinical samples were used to detect the relationship between GATA3 expression and tumor infiltrating lymphocyte (TIL) levels. Our results demonstrated that GATA3 was significantly overexpressed in TPBC tissues compared to normal tissues (P < 0.05). A positive correlation between GATA3 mRNA and protein levels was observed (R = 0.55, P < 0.05). Notably, high GATA3 expression was associated with poor overall survival (HR = 1.24, 95% confidence interval (CI) 1.25-11.76, P < 0.05). GSEA indicated significant enrichment of immune-related gene sets in low GATA3 expression groups. Furthermore, pathologic complete response (pCR) patients exhibited significantly lower GATA3 expression compared to residual disease (RD) patients. Mutation analysis revealed higher PIK3CA and TP53 mutation rates in high GATA3 expression groups. Finally, clinical validation data showed that the degree of TILs was significantly higher in the low GATA3 expression group. In conclusion, this study suggests that high GATA3 expression may be associated with poor prognosis and may reduce immune infiltration in TPBC.