?Targeting Pre-existing Club-Like Cells in Prostate Cancer Potentiates Androgen Deprivation Therapy

A critical knowledge gap in prostate cancer research is understanding whether castration-tolerant progenitor-like cells that reside in treatment-naïve tumors play a direct role in therapy resistance and tumor progression. Herein, we reveal that the castration tolerance of LSCmed (Lin-, Sca-1+, CD49fmed) progenitor cells, the mouse equivalent of human prostatic Club cells, arises not from intrinsic properties but from significant transcriptional reprogramming. Utilizing single-cell RNA sequencing of LSCmed cells isolated from prostate-specific Pten-deficient (Ptenpc-/-) mice, we identify the emergence of castration-resistant LSCmed cells enriched in stem-like features, driven by the transcription factor Fosl1/AP-1. We demonstrate that cells exhibiting Ptenpc-/- LSCmed characteristics are prevalent in the aggressive mesenchymal stem-like prostate cancer (MSPC) subtype recently identified in human castration-resistant prostate cancer (CRPC). Furthermore, our findings show that the dual-targeting agents JQ-1 and CX-6258—focused on Fosl1/AP-1 and PIM kinases, respectively—effectively suppress both the progenitor properties and the growth of mouse and human MSPC surrogates in vitro and in vivo. Thus, early eradication of castration-tolerant Club-like cells presents a promising therapeutic strategy to mitigate prostate cancer progression toward CRPC. Overall design: Two groups of experimental mice (n=8 each) were castrated and after 4-day recovery, we started treatment with JQ-1 (daily) and CX-6258 (bi-weekly) versus vehicle (Fig. 6C). After 28 days, mice were euthanized, then prostates were harvested, weighed, and processed for histopathological analyses or functional assays. Two mice per condition were used to perform digital spatial profiling using the GeoMx.