Dual inhibition of p38α MAPK and Casein kinase δ/ϵ as a novel treatment strategy for AR-independent and taxane-resistant advanced prostate cancer

Prostate cancer (PCa) is the most commonly diagnosed cancer and the second leading cause of cancer death among US men. Metastatic castration-resistant PCa (mCRPC) is a clinically advanced form of PCa, often associated with increased aggressiveness, metastatic potential, morbidity, and a higher risk of developing resistance to taxanes (TX), the first-line chemotherapy for mCRPC. Furthermore, cancer stemness and epithelial to mesenchymal trans-differentiation (EMT) potentially contribute to aggressiveness and the development of drug resistance in mCRPC. Here, we applied our drug development pipeline, secDrug, which utilizes a pharmacogenomics data-driven computational algorithm, to demonstrate that TAK-715 - a dual inhibitor of p38 MAPK and Casein kinase {delta}/{epsilon}, is a promising treatment for these advanced/lethal variants of PCa. Using in vitro cytotoxicity assays followed by cell-based functional assays in a panel of mCRPC cell lines representing TX-sensitive mCRPC, clonally derived TX-resistant lines, and a highly aggressive metastatic variant of mCRPC, we demonstrated the efficacy of TAK-715 treatment as a single agent and in combination with TX, including cancer stem-like cells. Further, we showed that the apoptotic effects of TAK-715 occur via a mitochondrial-mediated pathway. Bulk tumor RNA sequencing followed by pathway analysis identified genes associated with mitochondrial dysfunction and cell cycle arrest as the top molecular networks associated with TAK-715 single-treatment. HES1, a gene associated with nodal metastasis and PCa progression, was the top differentially expressed gene. Single-cell transcriptomics analysis revealed that TAK-715 treatment erodes the subclonal populations responsible for cancer stemness, metastasis, and drug resistance. The clinical significance of these findings was validated in silico using multiple patient datasets. Our results suggest that TAK-715 treatment has the potential to decrease oncogenic progression and cancer stem cell-like activity in drug-resistant, aggressive, and stem-like mCRPC cells.