Inhibition of the Hexosamine Biosynthetic Pathway Enhances Enzalutamide Response in Prostate Cancer Cells

Prostate cancer is one of the most frequently diagnosed malignancies in men and a leading cause of cancer-related mortality. Although androgen receptor signaling inhibitors (ARSIs) such as enzalutamide have significantly improved outcomes, therapeutic resistance remains a major clinical issue, potentially leading to disease progression and castration-resistant states. Emerging evidence highlights the role of metabolic adaptation in supporting therapeutic resistance. In particular, the hexosamine biosynthetic pathway (HBP) has gained attention for its role in producing UDP-N-acetylglucosamine, a key substrate for protein N- and O-glycosylation. This post-translational modification regulates protein stability, localization, and activity, and its dysregulation has been implicated in cancer progression and treatment failure. In this study, we will investigate the effects of FR054, a novel inhibitor of the HBP enzyme PGM3, in prostate cancer cells treated with enzalutamide. Our data show that FR054 can reduce cell proliferation and is associated with decreased expression of c-Myc, a transcription factor commonly associated with aggressive disease and therapeutic resistance. Notably, combined treatment with enzalutamide and FR054 also led to a significant increase in CHOP expression, indicative of the unfolded protein response (UPR) activation and endoplasmic reticulum (ER) stress-mediated apoptosis. These preliminary results suggest that HBP inhibition could disrupt glycosylation-dependent survival pathways and enhance sensitivity to enzalutamide by promoting proteotoxic stress and apoptotic signalling. Overall, our findings support further investigation of HBP inhibition as a complementary strategy to improve the efficacy of androgen receptor-targeted therapies in advanced prostate cancer.