Single-cell sequencing unveils the transcriptomic landscape of castration-resistant prostate cancer-associated fibroblasts and their association with prognosis and immunotherapy response.

BACKGROUND: The tumor microenvironment (TME) is increasingly acknowledged as a determinant in the malignant transformation and progression of castration-resistant prostate cancer (CRPC). Cancer-associated fibroblasts (CAFs), as a pivotal stromal cellular component in TME, are implicated in tumor progression and immune escape. However, the molecular characteristics and biological functions of CRPC-CAFs in prostate cancer necessitate further investigation. METHODS: We ascertained the differential transcriptomic profiles between CRPC-CAFs and PCa-CAFs through single-cell RNA-sequencing (scRNA-seq). Bulk RNA-seq data were employed to assess the prognostic implications of CRPC-CAFs in PCa. In addition, we examined the impact of CRPC-CAFs on the efficacy of immunotherapy and the composition of the tumor immune milieu. Furthermore, a subcutaneous PCa model was applied to determine the potential of TGF-β signaling blockade to augment the response to immunotherapeutic interventions. RESULTS: We observed a pronounced increase in the proportion of CAFs in CRPC compared to those in primary PCa. The functional pathways implicated in TGF-β signaling and ECM remodeling were remarkably upregulated in CRPC-CAFs. Moreover, gene regulatory network analysis uncovered substantial differences in the transcription factor activity profiles between CRPC-CAFs and PCa-CAFs. The elevated CRPC-CAFs abundance was associated with diminished recurrence-free survival and immunotherapy insensitivity. Substantially elevated infiltration of inhibitory immune cells and upregulated expression levels of immunosuppressive molecules were observed in patients with high CRPC-CAFs abundance. Importantly, administration of anti-TGF-β therapy remarkably potentiated the efficacy of anti-PD-1 immunotherapy through upregulating the anti-tumor immune response in the PCa model. CONCLUSION: Our results highlighted the impact of CRPC-CAFs on clinical prognosis and immunosuppressive tumor milieu, indicating that CRPC-CAFs may function as a promising therapeutic target for CRPC.