Integrative single-cell and spatial transcriptomic analysis reveals 4-HNE-related stromal remodeling in lung adenocarcinoma.

BACKGROUND: 4-HNE is a lipid peroxidation product involved in oxidative stress, tumor microenvironment remodeling, and tumor progression. This study aimed to characterize the cellular distribution, prognostic relevance, and functional roles of 4-HNE-related molecular features in lung adenocarcinoma. METHODS: 4-HNE-related targets were collected from ChEMBL and SwissTargetPrediction, followed by enrichment, differential expression, and survival analyses in TCGA-LUAD. A HNE_score was constructed using single-cell RNA-seq data. Cell-cell communication, fibroblast trajectory, transcription factor activity, spatial transcriptomics, machine learning, molecular docking, virtual knockout, and EdU assays were further performed. RESULTS: A total of 1,280 4-HNE-related candidate targets were identified and were mainly associated with xenobiotic response, PPAR signaling, estrogen signaling, and chemical carcinogenesis-related pathways. At the single-cell level, higher HNE_score values were mainly observed in macrophage, epithelial, and fibroblast populations. The HNE_high state was associated with enhanced stromal communication and a matrix-remodeling pattern involving fibroblasts, epithelial cells, and myeloid cells, together with enrichment of CTHRC1-positive myofibroblastic cancer-associated fibroblast features. RRM2 and CYP4B1 were identified as stable HNE_score-related prognostic candidates with opposite prognostic associations. RRM2 knockdown reduced DNA synthesis and proliferation in PC9 cells, supporting its functional relevance in lung adenocarcinoma. CONCLUSION: This study provides a multilayered map of 4-HNE-related cellular states in lung adenocarcinoma and links 4-HNE activity to stromal remodeling, altered cell-cell communication, and prognostic gene screening. RRM2 and CYP4B1 may represent key HNE-related prognostic candidates, with RRM2 showing functional relevance in tumor cell proliferation.