Nuclear ARRB1 induces pseudohypoxia and cellular metabolism reprogramming in prostate cancer

Tumour cells sustain their high proliferation rate through metabolic reprogramming, whereby cellular metabolism shifts from oxidative phosphorylation to aerobic glycolysis, even under normal oxygen levels. Hypoxia-inducible factor 1A (HIF1A) is a major regulator of this process, but its activation under normoxic conditions, termed pseudohypoxia, is not well documented. Here, using an integrative approach combining the first genome-wide mapping of chromatin binding for an endocytic adaptor, ARRB1, both in vitro and in vivo with gene expression profiling, we demonstrate that nuclear ARRB1 contributes to this metabolic shift in prostate cancer cells via regulation of HIF1A transcriptional activity under normoxic conditions through regulation of succinate dehydrogenase A (SDHA) and fumarate hydratase (FH) expression. ARRB1-induced pseudohypoxia may facilitate adaptation of cancer cells to growth in the harsh conditions that are frequently encountered within solid tumours. Our study is the first example of an endocytic adaptor protein regulating metabolic pathways. It implicates ARRB1 as a potential tumour promoter in prostate cancer and highlights the importance of metabolic alterations in prostate cancer. Synopsis Global chromatin occupancy- and gene expression data, together with 'pseudohypoxic' regulation of HIF1alpha stability establish a predominantly metabolic function of nuclear ARRB1 in prostate cancer. Unbiased, genome-wide occupancy map of nuclear ARRB1 Integrated expression data that highlight ARRB1-regulated gene networks Discovery of ARRB1 as novel metabolic and cell cycle control regulator Evidence for pseudohypoxic stabilisation of HIFA by ARRB1 Global chromatin occupancy- and gene expression data, together with 'pseudohypoxic' regulation of HIF1alpha stability establish a predominantly metabolic function of nuclear ARRB1 in prostate cancer.