A feedback loop between the androgen receptor and 6-phosphogluoconate dehydrogenase (6PGD) drives prostate cancer growth
Alterations to the androgen receptor (AR) signalling axis and cellular metabolism are hallmarks of prostate cancer. This study provides insight into both hallmarks by uncovering a novel link between AR and the pentose phosphate pathway (PPP). Specifically, we identify 6-phosphogluoconate dehydrogenase (6PGD) as an AR-regulated gene that is upregulated in prostate cancer. Knockdown of 6PGD impairs growth and elicits death of prostate cancer cells, at least in part due to increased oxidative stress. We investigated the therapeutic potential of targeting 6PGD using 2 specific inhibitors, physcion and S3. Both compounds exhibited substantial anti-cancer activity in multiple models of prostate cancer, including aggressive models of castration-resistant disease that are resistant to contemporary therapy. Mechanistically, 6PGD inhibits AMPK signalling, resulting in increased activity of the anabolic pathways regulated by ACC1 and mTOR. Importantly, the ability of S3 to inhibit prostate cancer growth was recapitulated in prospectively collected tumours using a patient-derived explant (PDE) system. Interestingly, inhibition of 6PGD decreases the expression and activity of AR in both cell lines and PDEs, revealing a novel positive feedback loop between these factors. Supporting the biological relevance of this feedback loop, co-targeting of AR and 6PGD was more effective than targeting either factor alone. Collectively, this work provides new insight into the dysregulated metabolism of prostate cancer and provides impetus for further investigation of co-targeting AR and the PPP as a novel therapeutic strategy. Overall design: RNA-seq following Enzalutamide treatment or AR knockdown in LNCaP cells.