Abstract 308: Reductive Carboxylation Contributes to Cardiac Adaptation in Response to the Oncometabolite D2-hydroxyglutarate

2020 ◽  
Vol 127 (Suppl_1) ◽  
Author(s):  
Anja Karlstaedt ◽  
Brandon Faubert ◽  
Heidi M Vitrac ◽  
Rebecca L Salazar ◽  
Benjamin D Gould ◽  
...  
Keyword(s):  
Cancer Cells ◽  
Rat Heart ◽  
Metabolic Flux ◽  
Adult Mouse ◽  
Epigenetic Modifications ◽  
Oxidative Decarboxylation ◽  
Flux Analysis ◽  
Chip Sequencing ◽  
Ventricular Cardiomyocytes ◽  
Reductive Carboxylation

Cancer cells rewire metabolism to support tumor growth and proliferation. In isocitrate dehydrogenase (IDH) 1 and 2 mutant tumors, increased plasma levels of the oncometabolite D-2-hydroxyglutarate (D2-HG) are associated with systemic effects, including myopathy. D2-HG causes inhibition of alpha-ketoglutarate dehydrogenase (AKGDH), which is associated with reduced cardiac contractile function. How tumor cells influence the metabolism of cardiomyocytes remains mostly unknown. Specific cancer cells use glutamine-dependent reductive carboxylation to circumvent defective mitochondrial metabolism by producing citrate and acetyl-CoA for lipid synthesis, which tumors require for growth. Here, we explore the hypothesis that inhibition of AKGDH by the oncometabolite D2-HG increases glutamine-dependent reductive carboxylation in the heart. We combined ex vivo rat heart perfusions with mass-spectrometry-based stable isotope tracer studies and in silico metabolic flux analysis. In response to D2-HG-mediated inhibition of AKGDH, we observed an increased reductive carboxylation of alpha-ketoglutarate to citrate rather than oxidative decarboxylation. This pathway increases glutamine uptake and glutamine-derived citrate formation in both working rat heart perfusions and cultured adult mouse ventricular cardiomyocytes. When we perfused rat hearts with 13C-labelled D2-HG, we observed a similarly increased formation of citrate. To identify which IDH isoform is responsible for redirecting carbon flux, we modulated IDH1, 2, and 3 in adult mouse ventricular cardiomyocytes using siRNAs. Reduced expression of IDH1 impaired reductive formation of citrate. Importantly, we observed a significant correlation between reductive citrate formation and epigenetic modifications of histones, including increased histone 3 lysine 9 acetylation and di-methylation. To explore these observations, we conducted ChIP-sequencing and identified distinct transcriptional remodeling. Taken together, we demonstrate how oncometabolic stress in the heart causes redirection of central carbon metabolism via reductive carboxylation, and provide evidence of how reductive-citrate formation may induce epigenetic modifications in the heart.

scholarly journals A feedback loop between the androgen receptor and 6-phosphogluoconate dehydrogenase (6PGD) drives prostate cancer growth

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Joanna L Gillis ◽  
Josephine A Hinneh ◽  
Natalie K Ryan ◽  
Swati Irani ◽  
Max Moldovan ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Androgen Receptor ◽  
Cancer Cells ◽  
Metabolic Flux ◽  
Therapeutic Potential ◽  
Regulatory Element ◽  
Single Agent ◽  
Flux Analysis ◽  
Prostate Cancer Cells ◽  
Insight Into

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 androgen-regulated gene that is upregulated in prostate cancer. AR increased the expression of 6PGD indirectly via activation of sterol regulatory element binding protein 1 (SREBP1). Accordingly, loss of 6PGD, AR or SREBP1 resulted in suppression of PPP activity, as revealed by 1,2-13C2 glucose metabolic flux analysis. Knockdown of 6PGD also impaired growth and elicited death of prostate cancer cells, at least in part due to increased oxidative stress. We investigated the therapeutic potential of targeting 6PGD using two specific inhibitors, physcion and S3, and observed substantial anti-cancer activity in multiple models of prostate cancer, including aggressive, therapy-resistant models of castration-resistant disease as well as prospectively-collected patient-derived tumour explants. Targeting of 6PGD was associated with two important tumour-suppressive mechanisms: first, increased activity of the AMP-activated protein kinase (AMPK), which repressed anabolic growth-promoting pathways regulated by ACC1 and mTOR; and second, enhanced AR ubiquitylation, associated with a reduction in AR protein levels and activity. Supporting the biological relevance of positive feedback between AR and PGD, pharmacological co-targeting of both factors was more effective in suppressing the growth of prostate cancer cells than single agent therapies. 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.

scholarly journals Reductive carboxylation is a major metabolic pathway in the retinal pigment epithelium

2016 ◽  
Vol 113 (51) ◽  
pp. 14710-14715 ◽  
Author(s):  
Jianhai Du ◽  
Aya Yanagida ◽  
Kaitlen Knight ◽  
Abbi L. Engel ◽  
Anh Huan Vo ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Retinal Pigment Epithelium ◽  
Cancer Cell ◽  
Metabolic Pathway ◽  
Metabolic Flux ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Cancer Cell Line ◽  
Flux Analysis ◽  
Reductive Carboxylation

The retinal pigment epithelium (RPE) is a monolayer of pigmented cells that requires an active metabolism to maintain outer retinal homeostasis and compensate for oxidative stress. Using13C metabolic flux analysis in human RPE cells, we found that RPE has an exceptionally high capacity for reductive carboxylation, a metabolic pathway that has recently garnered significant interest because of its role in cancer cell survival. The capacity for reductive carboxylation in RPE exceeds that of all other cells tested, including retina, neural tissue, glial cells, and a cancer cell line. Loss of reductive carboxylation disrupts redox balance and increases RPE sensitivity to oxidative damage, suggesting that deficiencies of reductive carboxylation may contribute to RPE cell death. Supporting reductive carboxylation by supplementation with an NAD+precursor or its substrate α-ketoglutarate or treatment with a poly(ADP ribose) polymerase inhibitor protects reductive carboxylation and RPE viability from excessive oxidative stress. The ability of these treatments to rescue RPE could be the basis for an effective strategy to treat blinding diseases caused by RPE dysfunction.

scholarly journals Global Transcription and Metabolic Flux Analysis of Escherichia coli in Glucose-Limited Fed-Batch Cultivations

2008 ◽  
Vol 74 (22) ◽  
pp. 7002-7015 ◽  
Author(s):  
K. Lemuth ◽  
T. Hardiman ◽  
S. Winter ◽  
D. Pfeiffer ◽  
M. A. Keller ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Carbon Flux ◽  
Metabolic Flux ◽  
Genetic Regulation ◽  
Tca Cycle ◽  
Carbon Limitation ◽  
Oxidative Decarboxylation ◽  
Flux Analysis ◽  
Fed Batch ◽  
K 12

ABSTRACT A time series of whole-genome transcription profiling of Escherichia coli K-12 W3110 was performed during a carbon-limited fed-batch process. The application of a constant feed rate led to the identification of a dynamic sequence of diverse carbon limitation responses (e.g., the hunger response) and at the same time provided a global view of how cellular and extracellular resources are used: the synthesis of high-affinity transporters guarantees maximal glucose influx, thereby preserving the phosphoenolpyruvate pool, and energy-dependent chemotaxis is reduced in order to provide a more economic “work mode.” σS-mediated stress and starvation responses were both found to be of only minor relevance. Thus, the experimental setup provided access to the hunger response and enabled the differentiation of the hunger response from the general starvation response. Our previous topological model of the global regulation of the E. coli central carbon metabolism through the crp, cra, and relA/spoT modulons is supported by correlating transcript levels and metabolic fluxes and can now be extended. The substrate is extensively oxidized in the tricarboxylic acid (TCA) cycle to enhance energy generation. However, the general rate of oxidative decarboxylation within the pentose phosphate pathway and the TCA cycle is restricted to a minimum. Fine regulation of the carbon flux through these pathways supplies sufficient precursors for biosyntheses. The pools of at least three precursors are probably regulated through activation of the (phosphoenolpyruvate-)glyoxylate shunt. The present work shows that detailed understanding of the genetic regulation of bacterial metabolism provides useful insights for manipulating the carbon flux in technical production processes.

scholarly journals Aerobic glycolysis in cancer cells supplies ATP while preventing excess metabolic thermogenesis

2021 ◽  
Author(s):  
Nobuyuki Okahashi ◽  
Tomoki Shima ◽  
Yuya Kondo ◽  
Chie Araki ◽  
Shuma Tsuji ◽  
...  
Keyword(s):  
Oxidative Phosphorylation ◽  
Cancer Cells ◽  
Metabolic Flux ◽  
Cancer Metabolism ◽  
Aerobic Glycolysis ◽  
Flux Analysis ◽  
13C Metabolic Flux Analysis ◽  
Metabolic Heat ◽  
Substrate Level ◽  
Atp Regeneration

A general feature of cancer metabolism is ATP regeneration via substrate-level phosphorylation even under normoxic conditions (aerobic glycolysis). However, it is unclear why cancer cells prefer the inefficient aerobic glycolysis over the highly efficient process of oxidative phosphorylation for ATP regeneration. Here, we show that a beneficial aspect of aerobic glycolysis is that it reduces metabolic heat generation during ATP regeneration. 13C-metabolic flux analysis of 12 cultured cancer cell lines and in silico metabolic simulation revealed that metabolic heat production during ATP regeneration via aerobic glycolysis was considerably lesser than that produced via oxidative phosphorylation. The dependency on aerobic glycolysis was partly alleviated upon culturing under low temperatures. In conclusion, thermogenesis is required for maintaining thermal homeostasis and can govern aerobic glycolysis in cancer cells.

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