Construction of a prognostic model for nasopharyngeal carcinoma based on serum exosomal circular RNAs and analysis of immune microenvironment

Accumulating evidence indicates that circular RNAs (circRNAs) play a pivotal role in tumor initiation and progression. However, their expression profiles and functional roles in serum exosomes from nasopharyngeal carcinoma (NPC) remain undefined. This study aims to explore the expression patterns, biological functions, and potential prognostic significance of circRNAs in serum exosomes of NPC. CircRNA expression profiles in serum exosomes were analyzed using a circRNA microarray, along with mRNA and miRNA data from RNA sequencing and the Gene Expression Omnibus (GEO). Initially, the competitive endogenous RNA (ceRNA) regulatory network was established by integrating multiple online databases and bioinformatics tools. Subsequently, LASSO and COX regression analyses were used to construct and validate the prognostic model. Additionally, the immunological characteristics analysis was conducted using CIBERSORT. qRT-PCR was performed to further validate the expression levels of circRNAs. Finally, a total of 314 differentially expressed circRNAs were identified in NPC serum exosomes, and a ceRNA regulatory network was constructed for three of them. The prognostic risk model effectively predicts outcomes for NPC patients. Immune cell infiltration analysis revealed a significant increase in M1-type macrophages in the high-risk group, whereas the low-risk group exhibited elevated levels of resting mast cells and activated CD4 memory T cells. Additionally, immune checkpoint gene analysis revealed significantly higher expression of CD276 and ICOSLG in the high-risk group compared to the low-risk group. Our findings suggest that serum exosomal circRNAs may be promising prognostic biomarkers in NPC, warranting further functional and clinical validation.