[Expression profile, immunoregulatory function, and clinical prognostic value of CENPN in breast cancer]

Objective: To investigate the expression profile of Centromere Protein N (CENPN) in invasive breast cancer (BRCA), evaluate its prognostic significance, and assess its involvement in immune regulation. Methods: The expression, prognostic value, and correlation with tumor immunogenicity of CENPN in BRCA tissues were analyzed based on The Cancer Genome Atlas (TCGA) database. Verification was conducted using cancerous and adjacent normal tissues from BRCA patients who underwent surgical treatment at Yantai Mountain Hospital between January 2022 and April 2023. CENPN expression in various immune cells in the blood was examined using the Human Protein Atlas (HPA) database. Genetic alterations of CENPN in breast cancer tissues were analyzed via the cBioPortal database. CENPN-related genes were screened using the GEPIA 2.0 database, and the interaction network between CENPN and similar genes was visualized with the STRING database. Gene Ontology (GO) enrichment analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, and Gene Set Enrichment Analysis (GSEA) were employed to explore the potential biological functions of CENPN. The correlation between CENPN expression and immune cell infiltration, as well as immune cell markers in BRCA tissues, was assessed using the TIMER 2.0 database. The effect of CENPN on the proliferation ability of breast cancer MCF-7 cells was detected by the CCK-8 assay, and its impact on the migration ability of MCF-7 cells was evaluated by a wound healing assay. Results: Analysis of TCGA database data revealed that CENPN expression was significantly higher in BRCA tissues compared to adjacent normal tissues (P＜0.05). Validation in our institutional cohort demonstrated a significantly higher positivity rate for CENPN in the 17 breast cancer tissues (82.4%) than in the paired paracancerous tissues (5.9%, P＜0.001). According to the HPA database, elevated CENPN expression was observed in T-reg cells, naïve B cells, and myeloid dendritic cells. Kaplan-Meier survival analysis indicated that patients with high CENPN expression had poorer overall survival (HR=1.39, P＜0.001), recurrence-free survival (HR=1.31, P＜0.001), post-progression survival (HR=1.28, P=0.036), and distant metastasis-free survival (HR=1.6, P＜0.001). Correlation analysis revealed a negative association between CENPN expression and tumor mutational burden in BRCA patients (r=-0.196, P＜0.001). Furthermore, CENPN expression was positively correlated with 5 out of 20 common immune checkpoint genes and negatively correlated with the remaining 15, suggesting its potential for predicting immunotherapy response. Analysis via the cBioPortal database showed that invasive lobular breast carcinoma had the highest CENPN alteration frequency, with amplification being the most common alteration in BRCA. Invasive mixed mucinous breast carcinoma exhibited the highest mutation frequency, and a key missense mutation (K329N) was identified as a potential driver in BRCA.GO enrichment analysis demonstrated that CENPN-related genes were primarily involved in cell cycle, DNA metabolic processes, cell division, nuclear lumen, chromosomes, nucleoplasm, and functions related to ATP, nucleotide, and small molecule binding. KEGG pathway analysis indicated significant enrichment in DNA replication, cellular senescence, mismatch repair, homologous recombination, p53 signaling pathway, and FOXO signaling pathway. Correlation analysis using the TIMER 2.0 database established associations between CENPN expression and the infiltration levels of B cells, CD4⁺ T cells, CD8⁺ T cells, macrophages, neutrophils, and dendritic cells in BRCA. Positive correlations were also found with markers for CD8⁺ T cells, B cells, T cells, and T-cell exhaustion.CCK-8 assay and wound healing experiments confirmed that CENPN knockdown significantly suppressed malignant phenotypes, including proliferation and migration, in MCF-7 cells. Additionally, CENPN knockdown was found to enhance the chemosensitivity of MCF-7 cells to the anti-tumor agents 5-fluorouracil and gemcitabine. Conclusion: CENPN serves as a potential prognostic biomarker and a novel target for immunotherapy in BRCA.