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Current therapeutic strategy for advanced prostate cancer is to suppress the androgen receptor (AR) signaling. However, lethal castration-resistant prostate cancer (CRPC) arises due to AR reactivation via multiple mechanisms, including mutations in the AR and cross-talk with other pathways such as NF-κB. We have previously identified two ionone-based antiandrogens (SC97 and SC245), which are full antagonists of the wild type and the clinically-relevant T877A, W741C and H874Y mutated ARs. Here, we discovered SC97 and SC245 also inhibit NF-κB. By synthesizing a series of derivatives of these two compounds, we have discovered a novel compound 3b that potently inhibits both AR and NF-κB signalling, including the AR F876L mutant. Compound 3b showed low micromolar antiproliferative activites in C4-2B and 22Rv1 cells, which express mutated ARs and are androgen-independent, as well as DU-145 and PC-3 cells, which exhibit constitutively activated NF-κB signalling. Our studies indicate 3b is effective against the CRPC cells.

A crucial event in prostate cancer progression is the transition from a hormone-sensitive to a lethal castration-refractory disease state. The antagonist-to-agonist conversion due to mutation in AR is a critical problem with the current clinically used antiandrogens. We aim to identify novel antiandrogens that remain as a pure antagonist even in the mutated ARs. By synthesizing a series of ionone-based chalcones, we have identified a novel chalcone (17) that is a pan-antagonist of the wild type and the clinically relevant T877A, W741C and H874Y mutated ARs in luciferase reporter assays in PC-3 cells. Further, chalcone 17 demonstrates sub-micromolar to low micromolar antiproliferative activity in LNCaP, MDA-PCa-2b, 22Rv1 and C4-2B prostate cancer cells, all of which express mutated ARs and confer resistance to the current clinically used antiandrogens. The results suggest that chalcone 17 could be a good candidate for further pre-clinical development as a novel antiandrogen for advanced prostate cancer.