PRKAR2B-HIF-1α loop promotes aerobic glycolysis and tumour growth in prostate cancer

Reprogramming of cellular metabolism is profoundly implicated in tumorigenesis and can be exploited to cancer treatment. Cancer cells are known for their propensity to use glucose-dependent glycolytic pathway instead of mitochondrial oxidative phosphorylation for energy generation even in the presence of oxygen, a phenomenon known as Warburg effect. The type II beta regulatory subunit of protein kinase A (PKA), PRKAR2B, is highly expressed in castration-resistant prostate cancer (CRPC) and contributes to tumour growth and metastasis. However, whether PRKAR2B regulates glucose metabolism in prostate cancer remains largely unknown.

Loss-of-function and gain-of-function studies were used to investigate the regulatory role of PRKAR2B in aerobic glycolysis. Real-time qPCR, Western blotting, luciferase reporter assay and chromatin immunoprecipitation were employed to determine the underlying mechanisms.

PRKAR2B was sufficient to enhance the Warburg effect as demonstrated by glucose consumption, lactate production and extracellular acidification rate. Mechanistically, loss-of-function and gain-of-function studies showed that PRKAR2B was critically involved in the tumour growth of prostate cancer. PRKAR2B was able to increase the expression level of hypoxia-inducible factor 1α (HIF-1α), which is a key mediator of the Warburg effect. Moreover, we uncovered that HIF-1α is a key transcription factor responsible for inducing PRKAR2B expression in prostate cancer. Importantly, inhibition of glycolysis by the glycolytic inhibitor 2-deoxy-d-glucose (2-DG) or replacement of glucose in the culture medium with galactose (which has a much lower rate than glucose entry into glycolysis) largely compromised PRKAR2B-mediated tumour-promoting effect. Similar phenomenon was noticed by genetic silencing of HIF-1α.

Our study identified that PRKAR2B-HIF-1α loop enhances the Warburg effect to enable growth advantage in prostate cancer.