Abstract A068: Prostate luminal progenitors as the cell-of-origin for androgen receptor-independent prostate cancer

Abstract

Abstract In the recent years, we have witnessed the emergence of androgen receptor (AR)-independent prostate cancer (AIPC) with the clinical use of second-generation androgen deprivation therapy, namely Enzalutamide and Abiraterone. Unluckily, treatment options for the end-stage AIPC patients are mainly palliative but not curable. However, the cellular origin and mechanisms involved in the evolution of AIPCs remain unclear. Previously, we have discovered that AR is not required for the survival and maintenance of progenitor property of CA stration- R esistant N kx3.1-expressing cells (CARNs), thus highlighting the AR-independent nature of this luminal progenitor subset. Interestingly, AR-deleted CARNs demonstrate gene expression profile that is highly similar to human neuroendocrine prostate cancer (NEPC), a subtype of AIPC. Moreover, upon Pten deletion and mutated Kras activation, AR-deleted CARNs can generate tumors exhibiting focal neuroendocrine differentiation, indicating the ability of CARNs to serve as a cell-of-origin for NEPC. Based on these observations, we hypothesize that AR-independent prostate luminal progenitor subsets are capable of initiating AIPC upon oncogenic transformation, while the transformed cells represent distinct subsets in AIPC that possess cancer stem cell property. In our latest assessments, we have validated the ability of CARNs to initiate NEPC using a novel genetically-engineered mouse model of prostate cancer. Moreover, we have established tumor organoids from CARNs-initiated AIPC, which are capable of generating allografts in both immunodeficient and immunocompetent mice, implying their immune-evading capability. Lastly, we have performed small molecule library screening on the transformed CARNs-derived tumor organoids to identify effective treatment options for AIPC. Taken together, our study has provided novel insights into the cellular origin of AIPCs. Consequently, targeting these prostate luminal progenitors-initiated tumor cells as well as their molecular property may serve as novel therapeutic strategies to overcome AR independence in prostate cancer. Citation Format: Chee Wai Chua. Prostate luminal progenitors as the cell-of-origin for androgen receptor-independent prostate cancer [abstract]. In: Proceedings of the AACR Special Conference: Advances in Prostate Cancer Research; 2023 Mar 15-18; Denver, Colorado. Philadelphia (PA): AACR; Cancer Res 2023;83(11 Suppl):Abstract nr A068.