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

Abstract

Purpose: DNA-dependent 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 (PCa), and is associated with poor outcomes. DNA-PK was previously nominated as a therapeutic target and DNA-PK inhibitors are currently undergoing clinical investigation. While 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 pharmacological 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-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 antiproliferative effects in aggressive disease.Conclusions: Findings herein unveil novel DNA-PK partners, substrates, and function in PCa. The role of DNA-PK impacts glycolysis through direct interaction with glycolytic enzymes and modulation of enzymatic activity. These events support energy production Research.

DNA-Dependent Protein Kinase Catalytic Subunit (DNA-PKcs): Beyond the DNA Double-Strand Break Repair

“…Interestingly, upstream stimulatory factor (USF) 1/2 heterodimer has been shown to be phosphorylated by DNA-PKcs resulting in fatty acid synthase (FASN) promoter activation ( Wong et al, 2009 ). Consistent with this, Dylgjeri et al (2022) have also found FASN as one of the novel DNA-PK partners, indicating an essential role of DNA-PKcs in regulating the cellular metabolism.…”

“…While we have long been appreciating the role of DNA-PKcs in DNA DSB repair mechanism, recent evidence highlighting a significant amount of DNA-PKcs being present in the cytoplasm ( Dylgjeri et al, 2022 ) suggests the novel role of DNA-PKcs in cells. By performing DNA-PK protein interactome, Dylgjeri et al (2022) have reported novel interacting partners of DNA-PK, including those involved in ribonucleic acid metabolism (DOT1L [histone methyltransferase], RPLs [L ribosomal proteins], HNRPs [heterogeneous nuclear ribonucleoprotein Ks], eEFs [eukaryotic elongation factors]), energy metabolism (PGK1, PKM2, FASN, VDAC-2 [voltage-dependent anion channel-2]), heat shock proteins (HSPs), zinc finger proteins (ZNFs), and inflammation (MIF [macrophage migration inhibitory factor]). This suggests that inhibition of DNA-PK is likely to inhibit multi-substrates at multiple locations (nucleus and cytoplasm), which may yield a complex outcome.…”

“…Despite the role of DNA-PKcs in the nucleus, recent evidence suggests that approximately 20% of the total DNA-PKcs protein levels have been detected in the cytoplasm of castration-resistant prostate cancer cells ( Dylgjeri et al, 2022 ). Furthermore, this study has demonstrated that DNA-PKcs promotes Warburg effect through phosphorylation of various enzymes involved in the glycolytic pathway including glyceraldehyde 3 phosphate dehydrogenase (GAPDH), phosphoglycerate kinase 1 (PGK1), enolase 1, and pyruvate kinase M2 (PKM2), hence suggesting that inhibition of DNA-PK in conjunction with aerobic glycolysis would increase antitumor efficacy ( Dylgjeri et al, 2022 ) ( Fig. 1 ).…”

Increased Resection at DSBs in G2-Phase Is a Unique Phenotype Associated with DNA-PKcs Defects That Is Not Shared by Other Factors of c-NHEJ

“…DNA-PKcs, when present in the nucleus contributes to repair and the regulation of transcription, but in the cytoplasm [63], it also has functions in energy metabolism [64], fatty acid synthesis [65] and aging [66]. Although the functions of DNA-PKcs continue to expand [67], its involvement in c-NHEJ has received the most attention and has been profoundly enriched by recent structural studies revealing intriguing aspects of its function in this repair pathway [68,69]. The work presented here helps to further develop and consolidate the functions of DNA-PKcs related to resection.…”

Druggable Metabolic Vulnerabilities Are Exposed and Masked during Progression to Castration Resistant Prostate Cancer

“…Metabolically, PKM2 has reduced enzymatic activity and slows down pyruvate production, allowing more upstream biomolecules to be available for other biosynthetic processes [ 137 ]. A recent report suggests that deoxyribonucleic acid (DNA)-dependent protein kinase (DNA-PK) may play a role in regulating increased glycolytic flux by phosphorylating aldolase and PKM2 to increase their enzymatic activities [ 138 ]. Interestingly, PKM2 also possess non-metabolic kinase activity and can function as a transcription factor, thereby promoting metastasis and regulating responses to hypoxia in PCa [ 139 , 140 , 141 , 142 , 143 ].…”