Single Cell and Bulk RNA-seq Profiling of Non-Metastatic Versus Bone-Metastatic Prostate Cancer Identifies the CXCL10-CXCR3 Axis as a Key Determinant of Tumor Microenvironment and Treatment Resistance

Background: Bone metastasis is a major determinant of morbidity and therapeutic failure in advanced prostate cancer (PCa); however, the transcriptional programs and tumor microenvironmental alterations driving metastatic progression remain incompletely understood. This study aimed to systematically characterize transcriptomic differences between non-metastatic and bone-metastatic PCa and to identify key microenvironmental signaling pathways involved in tumor survival and chemoresistance. Methods: Bulk RNA sequencing was performed on 49 non-metastatic and 28 bone-metastatic PCa specimens. Differential expression analysis was integrated with weighted gene co-expression network analysis (WGCNA), gene set enrichment analysis, and immune/stromal deconvolution. Key findings were validated using in vitro functional assays, including Transwell co-culture models, small interfering RNA (siRNA)-mediated gene silencing, cell viability, apoptosis, and docetaxel resistance analyses. Results: Transcriptomic profiling identified 574 differentially expressed genes. Bone-metastatic tumors were enriched in ribosome-related and translational pathways, whereas non-metastatic tumors displayed immune-associated signatures, including natural killer (NK) cell-mediated cytotoxicity and cytokine signaling. WGCNA revealed immune-related gene modules preferentially enriched in non-metastatic disease. Immune deconvolution demonstrated significantly higher infiltration of NK cells and endothelial cells in non-metastatic tumors. Chemokine-receptor analysis highlighted upregulation of the CXCL10-CXCR3 axis in non-metastatic PCa. In vitro, PCa cells expressed CXCR3, while endothelial cells markedly increased CXCL10 expression upon co-culture. Functional assays showed that endothelial-derived CXCL10 promoted PCa cell survival, suppressed apoptosis, and conferred resistance to docetaxel via CXCR3-dependent signaling; these effects were reversed by CXCL10 or CXCR3 knockdown. Conclusions: These findings uncover a context-dependent endothelial-immune chemokine network distinguishing non-metastatic from bone-metastatic PCa and identify the CXCL10-CXCR3 axis as a critical mediator of tumor survival and chemoresistance, suggesting a potential therapeutic vulnerability in advanced prostate cancer.