MP27-08: Evaluating the efficacy of a novel AKR1C3 inhibitor in patient-derived prostate cancer cell line and xenograft models

Joy C. Yang, Shu Ning, Sacramento, CA, Hans Adomat, Martin Gleave, Vancouver, Canada, Allen C. Gao, Christopher P. Evans, Chengfei Liu*, Sacramento, CA

Introduction: Prostate cancer (PCa) is a highly heterogeneous cancer type with distinct genomic and phenotypic characteristics that drive tumorigenesis and the differential response to drug therapies. A limit number of PCa cell lines and patient-derived xenograft (PDX) models hinders research to improve disease outcome. Some currently available PDX models were derived from the primary tumor samples are insufficient to recapitulate the clinical response at more advanced stages. In this study, we developed patient-derived models from patients with advanced disease and evaluated a novel AKR1C3 inhibitor in these novel models.

Methods: Samples received from our Pathology Biorepository Shared Resource were divided into four groups and subjected to pathological staining, RNA extraction, xenografting in NSG mice via renal capsule and subcutaneous implantation in SCID mice and conditional reprogramed cultures (CRCs) or organoid culturing. The AKR1C3 inhibitor PB was modified from celecoxib. AR and AR-V7 expression were determined by western blot. The effects of the AKR1C3 inhibitor on enzalutamide sensitivity were characterized by growth assay and colony formation assay.

Results: Eight PDX models have been developed from patients with high Gleason score and/or at the castration-resistant stages. Among the PDX models, one spontaneous indefinite cell line PS1172 was established. Early passage CRCs showed the epithelial morphology with AR positive expression. Through serially passaging PS1172 PDX with castration in SCID mice, the castration resistant cell line 1172CR was re-cultured from castration resistant PS1172 PDX tumors. 1172CR cells were resistant to enzalutamide treatment and expressed high level of AKR1C3 and AR-V7. A novel AKR1C3 inhibitor (PB) which displayed superior potential to inhibit AKR1C3 activity and suppress enzalutamide resistant prostate cancer cell growth was tested in these models. At the same dose, PB significantly suppressed 1172CR cell growth and colony formation compared to indomethacin and enzalutamide. PB also significantly suppressed AR/AR-V7 protein expression compared to indomethacin in 1172CR cells.

Conclusions: PS1172 and castration-resistant 1172CR cells are novel models with significant characteristics such as AR-V7 and AKR1C3. These models are ideal for small molecule testing and resistant mechanism investigating.

Source of Funding: This work was supported in part by grants NIH/NCI R37CA249108 (C, Liu), R01CA251253 (C, Liu), and Paul Calabresi Clinical Oncology K12 Program (C, Liu).