A Novel Role for DNA-PK in Metabolism by Regulating Glycolysis in Castration-Resistant Prostate Cancer.

PURPOSE: DNA-dependent protein kinase catalytic subunit (DNA-PKcs, herein referred as DNA-PK) is a multifunctional kinase of high cancer relevance. DNA-PK is deregulated in multiple tumor types, including prostate cancer, and is associated with poor outcomes. DNA-PK was previously nominated as a therapeutic target and DNA-PK inhibitors are currently undergoing clinical investigation. Although DNA-PK is well studied in DNA repair and transcriptional regulation, much remains to be understood about the way by which DNA-PK drives aggressive disease phenotypes. EXPERIMENTAL DESIGN: Here, unbiased proteomic and metabolomic approaches in clinically relevant tumor models uncovered a novel role of DNA-PK in metabolic regulation of cancer progression. DNA-PK regulation of metabolism was interrogated using pharmacologic and genetic perturbation using in vitro cell models, in vivo xenografts, and ex vivo in patient-derived explants (PDE). RESULTS: Key findings reveal: (i) the first-in-field DNA-PK protein interactome; (ii) numerous DNA-PK novel partners involved in glycolysis; (iii) DNA-PK interacts with, phosphorylates (in vitro), and increases the enzymatic activity of glycolytic enzymes ALDOA and PKM2; (iv) DNA-PK drives synthesis of glucose-derived pyruvate and lactate; (v) DNA-PK regulates glycolysis in vitro, in vivo, and ex vivo; and (vi) combination of DNA-PK inhibitor with glycolytic inhibitor 2-deoxyglucose leads to additive anti-proliferative effects in aggressive disease. CONCLUSIONS: Findings herein unveil novel DNA-PK partners, substrates, and function in prostate cancer. DNA-PK impacts glycolysis through direct interaction with glycolytic enzymes and modulation of enzymatic activity. These events support energy production that may contribute to generation and/or maintenance of DNA-PK-mediated aggressive disease phenotypes.

A quantitative proteomics approach identifies ETV6 and IKZF1 as new regulators of an ERG-driven transcriptional network.

Aberrant stem cell-like gene regulatory networks are a feature of leukaemogenesis. The ETS-related gene (ERG), an important regulator of normal haematopoiesis, is also highly expressed in T-ALL and acute myeloid leukaemia (AML). However, the transcriptional regulation of ERG in leukaemic cells remains poorly understood. In order to discover transcriptional regulators of ERG, we employed a quantitative mass spectrometry-based method to identify factors binding the 321 bp ERG +85 stem cell enhancer region in MOLT-4 T-ALL and KG-1 AML cells. Using this approach, we identified a number of known binders of the +85 enhancer in leukaemic cells along with previously unknown binders, including ETV6 and IKZF1. We confirmed that ETV6 and IKZF1 were also bound at the +85 enhancer in both leukaemic cells and in healthy human CD34+ haematopoietic stem and progenitor cells. Knockdown experiments confirmed that ETV6 and IKZF1 are transcriptional regulators not just of ERG, but also of a number of genes regulated by a densely interconnected network of seven transcription factors. At last, we show that ETV6 and IKZF1 expression levels are positively correlated with expression of a number of heptad genes in AML and high expression of all nine genes confers poorer overall prognosis.