Nicardipine is a putative EED inhibitor and has high selectivity and potency against chemoresistant prostate cancer in preclinical models

BackgroundIt is imperative to develop novel therapeutics to overcome chemoresistance, a significant obstacle in the clinical management of prostate cancer (PCa) and other cancers.MethodsA phenotypic screen was performed to identify novel inhibitors of chemoresistant PCa cells. The mechanism of action of potential candidate(s) was investigated using in silico docking, and molecular and cellular assays in chemoresistant PCa cells. The in vivo efficacy was evaluated in mouse xenograft models of chemoresistant PCa.ResultsNicardipine exhibited high selectivity and potency against chemoresistant PCa cells via inducing apoptosis and cell cycle arrest. Computational, molecular, and cellular studies identified nicardipine as a putative inhibitor of embryonic ectoderm development (EED) protein, and the results are consistent with a proposed mechanism of action that nicardipine destabilised enhancer of zeste homologue 2 (EZH2) and inhibited key components of noncanonical EZH2 signalling, including transducer and activator of transcription 3, S-phase kinase-associated protein 2, ATP binding cassette B1, and survivin. As a monotherapy, nicardipine effectively inhibited the skeletal growth of chemoresistant C4-2B-TaxR tumours. As a combination regimen, nicardipine synergistically enhanced the in vivo efficacy of docetaxel against C4-2 xenografts.ConclusionOur findings provided the first preclinical evidence supporting nicardipine as a novel EED inhibitor that has the potential to be promptly tested in PCa patients to overcome chemoresistance and improve clinical outcomes.

Automated summary

Nicardipine exhibited high selectivity and potency against chemoresistant PCa cells by inducing apoptosis and cell cycle arrest. It inhibited key components of noncanonical EZH2 signaling pathway, thus improving the clinical efficacy of chemoresistant prostate cancer.