A novel androgen receptor antagonist JJ‐450 inhibits enzalutamide‐resistant mutant ARF876L nuclear import and function. Issue 4 (23rd December 2019)

• Record Type: Journal Article
• Authors: Wu, Zeyu; Wang, Ke; Yang, Zhenyu; Pascal, Laura E.; Nelson, Joel B.; Takubo, Keita; Wipf, Peter; Wang, Zhou
• Is Part Of: Prostate. Volume 80:Issue 4(2020)
• Page Start: 319
• Page End: 328
• Publication Date: 2019-12-23
• Subjects: C4‐2 -- CRPC -- JJ‐450 -- LNCaP -- PC3 -- prostate cancer; Prostate -- Diseases -- Periodicals; 616
• DOI: 10.1002/pros.23945
• Languages: English
• ISSNs: 0270-4137

Abstract

Abstract: Background: Castration‐resistant prostate cancer can develop resistance to enzalutamide because of androgen receptor (AR) point mutations, AR overexpression, constitutively active AR splice variants, and/or elevated intratumoral androgen synthesis. The point mutation AR F876L was reported to be stimulated, instead of inhibited, by enzalutamide, thus contributing to enzalutamide resistance. We have recently developed JJ‐450 as a novel AR antagonist with the potential to treat enzalutamide‐resistant castration‐resistant prostate cancer (CRPC). Methods: We employed several assays to determine the impact of JJ‐450 and enzalutamide on prostate cancer cell lines expressing green fluorescent protein (GFP)‐AR F876L . These assays include a prostate‐specific antigen enhancer/promoter‐based luciferase assay to determine AR transcriptional activity, a quantitative real‐time polymerase chain reaction assay, and Western blot analysis to detect expression of AR‐target genes at the messenger RNA and protein level, fluorescence microscopy to show AR subcellular localization, and a 5‐bromo‐2′‐deoxyuridine assay to measure prostate cancer cell proliferation. Results: As expected, enzalutamide inhibited wild‐type (WT) AR but not AR F876L transcriptional activity in the luciferase assay. In contrast, JJ‐450 inhibited both WT‐AR and AR F876L transcriptional activity to a similar extent. Also, enzalutamide retarded androgen‐induced nuclear import of GFP‐AR, but not GFP‐AR F876L, whereas JJ‐450 retarded nuclear import of both GFP‐AR and GFP‐AR F876L . To further evaluate JJ‐450 inhibition of AR F876L, we stably transfected C4‐2 cells separately with GFP‐AR or GFP‐AR F876L . Enzalutamide inhibited endogenous AR‐target gene expression in C4‐2‐GFP‐AR WT, but not in the C4‐2–GFP‐AR F876L subline, whereas JJ‐450 inhibited AR‐target gene expression in both C4‐2 sublines. More importantly, enzalutamide inhibited proliferation of C4‐2‐GFP‐AR WT, but not of the C4‐2‐GFP‐AR F876L subline, whereas JJ‐450 inhibited proliferation of both C4‐2 sublines. Conclusion: JJ‐450 inhibits enzalutamide‐resistant AR F876L mutant nuclear translocation and function. Our findings suggest that JJ‐450 and its analogs should be further developed to provide a potential new approach for the treatment of enzalutamide‐resistant CRPC.