Abstract
BACKGROUND: To investigate the relationship between NXPH4 expression and prognosis in breast cancer (BRCA) and to elucidate its potential functional role. METHODS: NXPH4 expression data in breast tumor and normal tissues were collected from the TCGA, GTEx, and GEO databases. Its expression localization was assessed using single-cell sequencing and spatial transcriptomics. The impact of NXPH4 on breast cancer cell proliferation and apoptosis was validated experimentally via CCK-8, EdU assays, and Western Blot. Kaplan-Meier analysis was used to evaluate the correlation between NXPH4 expression and Overall Survival (OS), Disease-Specific Survival (DSS), Progression-Free Interval (PFI), and Disease-Free Interval (DFI) in the TCGA cohort. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Gene Set Enrichment Analysis (GSEA) were performed to explore the biological pathways associated with NXPH4-related differentially expressed genes. The associations of NXPH4 with immune cell infiltration and immune-related genes were examined across multiple datasets. The UALCAN and MethSurv databases were utilized to assess NXPH4 promoter methylation levels and the prognostic significance of specific hypermethylated sites. Drug sensitivity in BRCA patients was predicted using the GDSC1 and GDSC2 databases. RESULT: NXPH4 expression was significantly upregulated in breast cancer tissues and was primarily localized to malignant cells. In vitro experiments demonstrated that inhibiting NXPH4 affected breast cancer cell proliferation and apoptosis levels. Patients with high NXPH4 expression had a significantly shorter overall survival. The methylation level of the NXPH4 promoter was higher in tumor tissues compared to normal tissues, and methylation at specific sites was closely associated with patient prognosis. NXPH4 expression was correlated with cell cycle regulation, invasion processes, immune cell infiltration, and immune-related gene expression. High NXPH4 expression was associated with higher IC50 values for most chemotherapeutic drugs, suggesting relative chemoresistance, whereas drugs with lower IC50 values showed potentially better inhibitory effects. CONCLUSION: NXPH4 is highly expressed in breast cancer and is associated with poor prognosis. It may influence disease progression by regulating cell proliferation, immune infiltration, and other processes, indicating its potential as a prognostic biomarker and therapeutic target.