Single-cell and spatial transcriptomic profiling identifies a fibroblast-like endothelial state and the MDK-NCL signaling axis in prostate cancer microenvironment remodeling.

Prostate cancer exhibits substantial microenvironmental heterogeneity, but endothelial plasticity and its clinical relevance remain insufficiently characterized. In this study, we integrated single-cell RNA sequencing, spatial transcriptomic data, and bulk transcriptomic cohorts to investigate endothelial heterogeneity in prostate cancer. Single-cell analysis identified a fibroblast-like endothelial (FLE) population characterized by the coexistence of endothelial and stromal transcriptional features. Endothelial subclustering further revealed a mesenchymal-like subset enriched in extracellular matrix remodeling, developmental, and lipid metabolic programs, supporting the presence of an EndMT-like endothelial state. Cell-cell communication analysis showed that FLE cells displayed strong incoming and outgoing signaling activity, with the MDK-NCL interaction emerging as a candidate ligand-receptor axis within the prostate cancer microenvironment. Based on an FLE-enriched co-expression module identified by hdWGCNA, we constructed a FLE-related prognostic model that consistently stratified patient outcomes across the TCGA-PRAD, GSE116918, and GSE46602 cohorts. High-risk patients exhibited poorer survival outcomes, while SHAP analysis showed cohort-dependent contributions of SPARC, IGFBP7, ESAM, CRIP2, and COL4A1 to risk prediction. Experimental validation demonstrated elevated NCL expression in prostate cancer tissues and cell lines. NCL knockdown suppressed cell viability, colony formation, and DNA synthesis in PC3 and DU145 cells. Collectively, these findings identify an FLE state associated with active intercellular communication and adverse clinical outcomes, highlighting endothelial plasticity and the MDK-NCL axis as potential components of prostate cancer microenvironment remodeling.