Integrated single-cell and bulk transcriptomic analyses reveal ferro-aging-related molecular characteristics and immunological heterogeneity in renal cell carcinoma

Objective Ferro-aging, characterized by chronic iron-dependent oxidative damage and age-related transcriptional alterations, may contribute to the heterogeneity of renal cell carcinoma (RCC). This study aimed to identify ferro-aging-related candidate core genes and evaluate their diagnostic value and biological relevance in RCC. Methods GSE40435 and GSE66272 were integrated as the training cohort, and GSE53757 was used for external validation. Ferro-aging-related candidate genes were identified by differential expression and machine-learning analyses to construct a diagnostic model. Their biological relevance was investigated using immune, molecular subtype, WGCNA, single-cell, and virtual knockout analyses, followed by experimental validation of gene expression and LOX function. Results A total of 26 ferro-aging-related differentially expressed genes were identified, from which five candidate core genes—DPEP1, LCN2, LOX, NOX4, and TLR4—were selected. The five-gene diagnostic model showed strong discriminatory performance, with AUCs of 0.952 and 0.978 in the training and independent validation cohorts, respectively. These genes were associated with immune-related and molecular features and exhibited heterogeneous cell-type-resolved expression patterns, with the combined five-gene signature showing relatively higher module scores in the epithelial/tumor epithelial compartment. Virtual knockout identified NNMT and FAM134B as potential common response nodes. LOX knockdown significantly inhibited RCC cell proliferation, migration, and invasion and increased lipid peroxidation. Conclusion DPEP1, LCN2, LOX, NOX4, and TLR4 represent potential ferro-aging-related diagnostic biomarkers in RCC. LOX may be associated with RCC progression and ferro-aging-related lipid peroxidation, although the underlying mechanisms require further investigation.