Ratiometric Inclusion of Fibroblasts Promotes Both Castration‐Resistant and Androgen‐Dependent Tumorigenic Progression in Engineered Prostate Cancer Tissues

Abstract To investigate the ratiometric role of fibroblasts in prostate cancer (PCa) progression, this work establishes a matrix‐inclusive, 3D engineered prostate cancer tissue (EPCaT) model that enables direct coculture of neuroendocrine‐variant castration‐resistant (CPRC‐ne) or androgen‐dependent (ADPC) PCa cells with tumor‐supporting stromal cell types. Results show that the inclusion of fibroblasts within CRPC‐ne and ADPC EPCaTs drives PCa aggression through significant matrix remodeling and increased proliferative cell populations. Interestingly, this is observed to a much greater degree in EPCaTs formed with a small number of fibroblasts relative to the number of PCa cells. Fibroblast coculture also results in ADPC behavior more similar to the aggressive CRPC‐ne condition, suggesting fibroblasts play a role in elevating PCa disease state and may contribute to the ADPC to CRPC‐ne switch. Bulk transcriptomic analyses additionally elucidate fibroblast‐driven enrichment of hallmark gene sets associated with tumorigenic progression. Finally, the EPCaT model clinical relevancy is probed through a comparison to the Cancer Genome Atlas (TCGA) PCa patient cohort; notably, similar gene set enrichment is observed between EPCaT models and the patient primary tumor transcriptome. Taken together, study results demonstrate the potential of the EPCaT model to serve as a PCa‐mimetic tool in future therapeutic development efforts.