WNY-0824

Though multifactorial, BET and PLK1 proteins have been found to be key players in the oncogenic process leading to castration‐resistant prostate cancer through regulation of AR and MYC‐mediated transcription. Hence, dual inhibition of these proteins appears to be an auspicious approach for CRPC therapy. WNY0824 has been reported to exhibit nanomolar range inhibition as well as significant anti‐proliferative activity on AR‐positive CRPC cells in vitro. However, structural, and mechanistic events associated with its dual inhibitory and anti‐proliferative mechanisms remain unclear. Utilizing integrative computer‐assisted atomistic techniques, analyses revealed that the dual‐inhibitory activity of WNY0824 against BRD4 and PLK1 proteins is mediated by conserved residues present in the binding cavities of both proteins which are shown to elicit various strong intermolecular interactions and thus favour binding affinity. Also, binding orientation of the ligand at the protein binding cavities allowed for important hydrophobic interactions which resulted in high binding free energy of −42.50 kcal/mol and −51.64 kcal/mol towards BRD4 and PLK1, respectively. While van der Waals interactions are very important to ligand binding in BRD4‐WNY complex, electrostatic interactions are pertinent to PLK1‐WNY complex. Intriguingly, WNY0824 triggered conformational alterations in both proteins through increased structural instability, decreased structural compactness and mitigation in exposure of residues to solvent surface area. Consequently, critical interactions peculiar to the oncogenic activities of BRD4 and PLK1 were inhibited, a phenomenon that results in an antagonism of CRPC progression. The mechanistic insights presented in this report would further assist in the structure‐based design of improved inhibitors useful in CRPC therapy.

Castration-resistant prostate cancer (CRPC) is a lethal disease with few treatment alternatives once patients become resistant to second-generation antiandrogens. In CRPC, BET proteins are key regulators of AR- and MYC-mediated transcription, while the PLK1 inhibitor potentially downregulates AR and MYC besides influencing the cell cycle. Therefore, synchronous inhibition of BET and PLK1 would be a promising approach for CRPC therapy. This study developed a dual BET and PLK1 inhibitor WNY0824 with nanomolar and equipotent inhibition of BRD4 and PLK1. In vitro, WNY0824 exhibited excellent antiproliferation activity on AR-positive CRPC cells and induced apoptosis. These activities are attributable to its disruption of the AR-transcriptional program and the inhibition of the ETS pathway. Furthermore, WNY0824 downregulated MYC and induced mitotic abnormality. In vivo, oral WNY0824 administration suppressed tumor growth in the CRPC xenograft model of enzalutamide resistance. These findings suggest that WNY0824 is a selective dual BET and PLK1 inhibitor with potent anti-CRPC oncogenic activity and provides insights into the development of other novel dual BET- and PLK1-inhibiting drugs.