Ketone Body Utilization Research Articles

A Turkish Patient With Succinyl-CoA:3-Oxoacid CoA Transferase Deficiency Mimicking Diabetic Ketoacidosis

Succinyl-CoA:3-oxoacid CoA transferase (SCOT) deficiency is an autosomal recessive disorder of ketone body utilization that is clinically characterized with intermittent ketoacidosis crises. We rep...

EPN-09KETOLYTIC AND GLYCOLYTIC ENZYMATIC EXPRESSION IN PAEDIATRIC EPENDYMOMAS: IMPLICATION FOR KETOGENIC DIET THERAPY

EPN-09. KETOLYTIC AND GLYCOLYTIC ENZYMATIC EXPRESSION IN PAEDIATRIC EPENDYMOMAS: IMPLICATION FOR KETOGENIC DIET THERAPY Lisa C.D. Storer1, Angeline Darren1, Simon M.L. Paine2, Jen Kearns3, Robert Layfield4, David A. Walker1, and Richard G. Grundy1; Children’s Brain Tumour Research Centre, School of Medicine, University of Nottingham, Nottingham, UK; Department of Neuropathology, Nottingham University Hospitals NHS Trust, Nottingham, UK; Division of Nutritional Sciences, University of Nottingham, Nottingham, UK; School of Life Sciences, University of Nottingham, Nottingham, UK Ependymoma is the second most common paediatric malignant brain tumour. Overall survival remains relatively poor, and at relapse is dismal. One potential strategy to improve outcome is exploiting the metabolic differences between normal and tumour cells. Under normal physiological conditions, brain cells metabolise glucose for energy. If “starved” of glucose, ketone bodies are metabolised. Mitochondrial defects in brain tumour cells obviate this metabolic flexibility resulting in a dependence on glycolytic energy (Warburg effect). Thus, a high fat, low carbohydrate ketogenic diet (KD) may control tumour growth. We evaluated the expression of ketolytic enzymes; succinyl-CoA:3-oxoacid CoA transferase 1 (OXCT1) and D-b-hydroxybutyrate dehydrogenase 1 (BDH1), both involved in ketone body utilization and the glycolytic enzyme; pyruvate kinase M2 (PKM2), essential for aerobic glycolysis, in 75 paediatric ependymomas by immunohistochemistry. Expression was assessed as low (,20%) or high (.20%).84%showed lowexpression of OXCT1 and 91% of BDH1. Lowexpression of either results in an inability to metabolise ketones. 82% showed high expression of PKM2, increasing the Warburg effect and when combined with low expression of BDH1 (69%) or OXCT1 (83%), the optimal immunohistochemistry profile, arrests ketone metabolism. Children aged ,36 months were 5 times less likely to show high expression of OXCT1 compared to ≥36 months (p 1⁄4 0.0321) and 7 times more likely to show high expression of PKM2 (p 1⁄4 0.0097). The KD therefore offers a potential addition to current therapies including at relapse. However, the KD would need to be carefully evaluated prior to acceptance as a useful additional therapy. Neuro-Oncology 18:iii30–iii39, 2016. doi:10.1093/neuonc/now070.8 #The Author(s) 2016. Published by Oxford University Press on behalf of the Society for Neuro-Oncology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

High-fat diet-induced obesity stimulates ketone body utilization in osteoclasts of the mouse bone

Previous studies have shown that high-fat diet (HFD)-induced obesity increases the acetoacetyl-CoA synthetase (AACS) gene expression in lipogenic tissue. To investigate the effect of obesity on the AACS gene in other tissues, we examined the alteration of AACS mRNA levels in HFD-fed mice. In situ hybridization revealed that AACS was observed in several regions of the embryo, including the backbone region (especially in the somite), and in the epiphysis of the adult femur. AACS mRNA expression in the adult femur was higher in HFD-fed mice than in normal-diet fed mice, but this increase was not observed in high sucrose diet (HSD)-induced obese mice. In addition, HFD-specific increases were observed in the 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) and interleukin (IL)-6 genes. Moreover, we detected higher AACS mRNA expression in the differentiated osteoclast cells (RAW 264), and found that AACS mRNA expression was significantly up-regulated by IL-6 treatment only in osteoclasts. These results indicate the novel function of the ketone body in bone metabolism. Because the abnormal activation of osteoclasts by IL-6 induces bone resorption, our data suggest that AACS and ketone bodies are important factors in the relationship between obesity and osteoporosis.

Circulation : Clinical Summaries

<i>Circulation</i> : Clinical Summaries

Myocardial energy provision is preserved by increased utilization of glucose and ketone bodies in CD36 knockout mice

AimsCD36 is an important transporter of long-chain fatty acids (LCFAs) in the myocardium. As we have reported previously, CD36-deficient patients demonstrate a marked reduction in myocardial uptake of 123I-15-(p-iodophenyl)-(R, S)-methyl pentadecanoic acid (BMIPP), which is an analog of LCFAs, while myocardial 18F-fluorodeoxy-glucose (FDG) uptake is increased. However, it has not been clarified whether energy provision is preserved in patients with CD36 deficiency. The aims of the current study were to investigate the myocardial uptake of glucose and alterations in myocardial metabolites in wild-type (WT) and CD36 knockout (KO) mice. Methods and resultsHigh-resolution positron emission tomography (PET) demonstrated markedly enhanced glucose uptake in KO mouse hearts compared with those of WT mice in real-time. The myocardial protein expression of glucose transporter protein 1 (GLUT1) was significantly enhanced in KO mice compared to WT mice, whereas that of GLUT4 was not altered. While the myocardial expression of genes involved in fatty acid metabolism did not increase in KO mice, that of genes related to glucose utilization compensatorily increased in KO mice. The metabolomic analysis of cardiac tissues revealed that the myocardial concentrations of ATP and phosphocreatine were maintained, even in KO mice. The concentration of 3-hydroxybutyric acid and mRNA expression of hydroxybutyrate dehydrogenase in the heart were significantly higher in KO than in WT mice. ConclusionThese data suggest that high-energy phosphate might be preserved by the increased utilization of glucose and ketone bodies in CD36KO mouse hearts under conditions of deficient LCFA uptake.

SIRT3 Mediates Multi-Tissue Coupling for Metabolic Fuel Switching

SIRT3 is a member of the Sirtuin family of NAD(+)-dependent deacylases and plays a critical role in metabolic regulation. Organism-wide SIRT3 loss manifests in metabolic alterations; however, the coordinating role of SIRT3 among metabolically distinct tissues is unknown. Using multi-tissue quantitative proteomics comparing fasted wild-type mice to mice lacking SIRT3, innovative bioinformatic analysis, and biochemical validation, we provide a comprehensive view of mitochondrial acetylation and SIRT3 function. We find SIRT3 regulates the acetyl-proteome in core mitochondrial processes common to brain, heart, kidney, liver, and skeletal muscle, but differentially regulates metabolic pathways in fuel-producing and fuel-utilizing tissues. We propose an additional maintenance function for SIRT3 in liver and kidney where SIRT3 expression is elevated to reduce the acetate load on mitochondrial proteins. We provide evidence that SIRT3 impacts ketone body utilization in the brain and reveal a pivotal role for SIRT3 in the coordination between tissues required for metabolic homeostasis.

Rapid adaptation of rat brain and liver metabolism to a ketogenic diet: an integrated study using (1)H- and (13)C-NMR spectroscopy.

The ketogenic diet (KD) is an effective alternative treatment for refractory epilepsy in children, but the mechanisms by which it reduces seizures are poorly understood. To investigate how the KD modifies brain metabolism, we infused control (CT) and 7-day KD rats with either [1-(13)C]glucose (Glc) or [2,4-(13)C2]β-hydroxybutyrate (β-HB). Specific enrichments of amino acids (AAs) measured by (1)H- and (13)C-NMR in total brain perchloric acid extracts were similar between CT and KD rats after [1-(13)C]Glc infusion whereas they were higher in KD rats after [2,4-(13)C2]β-HB infusion. This suggests better metabolic efficiency of ketone body utilization on the KD. The relative rapid metabolic adaptation to the KD included (1) 11%-higher brain γ-amino butyric acid (GABA)/glutamate (Glu) ratio versus CT, (2) liver accumulation of the ketogenic branched-chain AAs (BCAAs) leucine (Leu) and isoleucine (ILeu), which were never detected in CT, and (3) higher brain Leu and ILeu contents. Since Glu and GABA are excitatory and inhibitory neurotransmitters, respectively, higher brain GABA/Glu ratio could contribute to the mechanism by which the KD reduces seizures in epilepsy. Increased BCAA on the KD may also contribute to better seizure control.

Inborn errors of ketone body utilization.

Succinyl-CoA:3-ketoacid CoA transferase (SCOT) deficiency and mitochondrial acetoacetyl-CoA thiolase (beta-ketothiolase or T2) deficiency are classified as autosomal recessive disorders of ketone body utilization characterized by intermittent ketoacidosis. Patients with mutations retaining no residual activity on analysis of expression of mutant cDNA are designated as severe genotype, and patients with at least one mutation retaining significant residual activity, as mild genotype. Permanent ketosis is a pathognomonic characteristic of SCOT-deficient patients with severe genotype. Patients with mild genotype, however, may not have permanent ketosis, although they may develop severe ketoacidotic episodes similar to patients with severe genotype. Permanent ketosis has not been reported in T2 deficiency. In T2-deficient patients with severe genotype, biochemical diagnosis is done on urinary organic acid analysis and blood acylcarnitine analysis to observe characteristic findings during both ketoacidosis and non-episodic conditions. In Japan, however, it was found that T2-deficient patients with mild genotype are common, and typical profiles were not identified on these analyses. Based on a clinical study of ketone body utilization disorders both in Japan and worldwide, we have developed guidelines for disease diagnosis and treatment. These diseases are treatable by avoiding fasting and by providing early infusion of glucose, which enable the patients to grow without sequelae.

Heterozygous Monocarboxylate Transporter 1 (MCT1, SLC16A1) Deficiency as a Cause of Recurrent Ketoacidosis.

We describe two half-siblings with monocarboxylate transporter 1 (MCT1, SLC16A1) deficiency, a defect on ketone body utilization, that has only recently been identified (van Hasselt et al., N Engl J Med, 371:1900-1907, 2014) as a cause for recurrent ketoacidoses. Our index patient is a boy with non-consanguineous parents who had presented acutely with impaired consciousness and severe metabolic ketoacidosis following a 3-day history of gastroenteritis at age 5 years. A 12.5-year-old half-brother who shared the proband's mother also had a previous history of recurrent ketoacidoses. Results of mutation and enzyme activity analyses in proband samples advocated against methylacetoacetyl-coenzyme A thiolase ("beta-ketothiolase") and succinyl-coenzyme A: 3-oxoacyl coenzyme A transferase (SCOT) deficiencies. A single heterozygous c.982C>T transition in the SLC16A1 gene resulting in a stop mutation (p.Arg328Ter) was detected in both boys. It was shared by their healthy mother and by the proband's half-sister, but was absent in the proband's father. MCT1 deficiency may be more prevalent than is apparent, as clinical manifestations can occur both in individuals with bi- and monoallelic mutations. It may be an important differential diagnosis in recurrent ketoacidosis with or without hypoglycemia, particularly in the absence of any specific metabolic profiles in blood and urine. Early diagnosis may enable improved disease management. Careful identification of potential triggers of metabolic decompensations in individuals even with single heterozygous mutations in the SLC16A1 gene is indicated.

Monocarboxylate Transporter 1 Deficiency and Ketone Utilization

Ketoacidosis is a potentially lethal condition caused by the imbalance between hepatic production and extrahepatic utilization of ketone bodies. We performed exome sequencing in a patient with recurrent, severe ketoacidosis and identified a homozygous frameshift mutation in the gene encoding monocarboxylate transporter 1 (SLC16A1, also called MCT1). Genetic analysis in 96 patients suspected of having ketolytic defects yielded seven additional inactivating mutations in MCT1, both homozygous and heterozygous. Mutational status was found to be correlated with ketoacidosis severity, MCT1 protein levels, and transport capacity. Thus, MCT1 deficiency is a novel cause of profound ketoacidosis; the present work suggests that MCT1-mediated ketone-body transport is needed to maintain acid–base balance.

Acute nutritional ketosis: implications for exercise performance and metabolism.

Ketone bodies acetoacetate (AcAc) and D-β-hydroxybutyrate (βHB) may provide an alternative carbon source to fuel exercise when delivered acutely in nutritional form. The metabolic actions of ketone bodies are based on sound evolutionary principles to prolong survival during caloric deprivation. By harnessing the potential of these metabolic actions during exercise, athletic performance could be influenced, providing a useful model for the application of ketosis in therapeutic conditions. This article examines the energetic implications of ketone body utilisation with particular reference to exercise metabolism and substrate energetics.

Abstract 1439: Combination of metformin plus orlistat prevents tumor progression: novel role of the metabolic hormone fibroblast growth factor 21 (FGF21)

Abstract Caloric Restriction (CR) is known to be the only model to consistently increase the lifespan and postpone age-related diseases in all species. CR increases glycogenolysis, lipolysis with fatty acid and ketone body utilization and accelerates protein catabolism. We previously reported that CR induces metabolic and signaling changes that affect the tumor microenvironment preventing the growth of 4T1 mammary tumors and their metastases. 4T1 is a highly metastatic mouse breast cancer model which resembles breast cancer in patients. Obesity causes subclinical inflammation in adipose tissue that contributes to insulin resistance and cancer progression. Chronic inflammation predisposes to different forms of cancer and diabetes, and is correlated with increased risk of breast cancer. CR reduces insulin resistance, adiposity and inflammation and the anti-diabetic drug metformin (MET) is a CR mimetic agent. In this study, we evaluated whether the combination of MET with the anti-obesity drug orlistat (OR) enhances the CR mimetic and anti-cancer properties of MET on 4T1 mammary tumor cells. Female 8 week-old BALB/c mice received: vehicle, MET (in drinking water, 3mg/ml), OR i.p. injection (240mg/kg/day) or MET + OR. After 3 weeks on drugs, 4T1 cells (105) were injected into mice and drugs continued till the end of the experiment. Treated-mice had a reduced adiposity (p&amp;lt;0.05) without any signs of toxicity. At 30 days, MET + OR co-treatment reduced tumor volume (p&amp;lt;0.01) and displayed a range of cellular alterations such as decreased proliferative index (p&amp;lt;0.05); increased apoptotic rate (p&amp;lt;0.01) and altered intra-tumor collagen deposit. MET + OR treatment reduced total vessel length (p&amp;lt;0.01) and the number of spontaneous lung metastases (p&amp;lt;0.01). In addition, combinations of MET (1-2.5mM) + OR (2.5-5µM) decreased in vitro 4T1 mammary cell proliferation (p&amp;lt;0.01), adhesion (p&amp;lt;0.05) and migration (p&amp;lt;0.01) compared to vehicle and drugs alone. Interestingly, we found that levels of fibroblast growth factor 21 (FGF21), an endocrine factor that regulates glucose and lipid metabolism, were significantly increased with MET + OR treatment (p&amp;lt;0.05). It has been shown that increased circulating levels of FGF21 correlated with decreased obesity and increased sensitivity to insulin; but up to date the role of FGF21 in tumor progression was not elucidated. We found that treatment of 4T1 cells with MET + OR increased the secretion of FGF21 (p&amp;lt;0.05) measured by ELISA assays. To elucidate the role of FGF21; we initially demonstrated that addition of recombinant protein FGF21 (0-10nM) did not change 4T1 cell proliferation. In contrast, the reduced cell proliferation and adhesion induced by MET + OR, were abolished by the pre- and co-treatment with anti-FGF21 neutralizing antibody; indicating that FGF21 may play an important role. Our results provide a new rationale basis for the use of MET plus OR as cancer therapy. Citation Format: Shobika Sivaram, Erdene Baljinnyam, Kousaku Iwatsubo, Lydia I. Puricelli, Mariana S. De Lorenzo. Combination of metformin plus orlistat prevents tumor progression: novel role of the metabolic hormone fibroblast growth factor 21 (FGF21). [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1439. doi:10.1158/1538-7445.AM2014-1439

Ketone Body Metabolism Attenuates Oxidative Stress and Cardiac Remodeling in Pressure Overload Heart Failure

The shift of energy substrate from fatty acid to glucose accompanied by myocardial energy compromise is the hallmark of metabolic remodeling in pathological cardiac hypertrophy. However, it has not been investigated the pathogenic contribution of ketone body metabolism in heart failure. Pressure overload heart failure was introduced with the transverse aortic constriction (TAC). Microarray and mitochondrial iTRAQ proteomics revealed that the expression of Bdh1, an enzyme that catalyzes the NAD+/NADH coupled interconversion of acetoacetate and beta-hydroxybutyrate (betaOHB), was increased 2.5-fold in TAC-operated heart. Ketone body oxidation determined by measuring 14CO2 released from [1-14C] betaOHB in the isolated perfused hearts was upregulated 1.8-fold in TAC-operated heart. To investigate the functional significance of increased ketone body oxidation we generated heart-specific Bdh1 Tg mice which had 1.7-fold increase of ketone body oxidation in the heart. When subjected to TAC operation Bdh1 Tg mice were resistant to cardiac hypertrophy, contractile dysfunction, and fibrosis. Immunochemical detection of carbonylated proteins demonstrated that protein oxidative damage was ameliorated in Bdh1 Tg mice. In vitro study with rat neonatal cardiomyocytes revealed that the adenovirus-mediated Bdh1 overexpression decreased ROS production and apoptosis. The present study demonstrates that ketone body oxidation is promoted in hypertrophied hearts. Increased ketone body utilization reduces oxidative stress and protects against heart failure progression after chronic pressure overload.

A Cause of Permanent Ketosis: GLUT-1 Deficiency.

GLUT-1-deficiency syndrome (GLUT1-DS; OMIM 606777) is a treatable metabolic disorder caused by a mutation of SLC2A1 gene. The functional deficiency of the GLUT1 protein leads to an impaired glucose transport into the brain, resulting in neurologic disorders.We report on a 6-month-old boy with preprandial malaises who was treated monthly by a sorcerer because of a permanent acetonemic odor. He subsequently developed pharmaco-resistant seizures with microcephaly and motor abnormalities. Metabolic explorations were unremarkable except for a fasting glucose test which revealed an abnormal increase of blood ketone bodies. At the age of 35 months, GLUT1-DS was diagnosed based on hypoglycorrhachia with a decreased CSF to blood glucose ratio, and subsequent direct sequencing of the SLC2A1 gene revealed a de novo heterozygous mutation, c.349A>T (p.Lys117X) on exon 4. It was noteworthy that the patient adapted to the deficient cerebral glucose transport by permanent ketone body production since early life. Excessive ketone body production in this patient provided an alternative energy substrate for his brain. We suggest a cerebral metabolic adaptation with upregulation of monocarboxylic acid transporter proteins (MCT1) at the blood-brain barrier provoked by neuroglycopenia and allowing ketone body utilization by the brain. This case illustrates that GLUT1-DS should be considered in the differential diagnosis of permanent ketosis.

Early Decline in Glucose Transport and Metabolism Precedes Shift to Ketogenic System in Female Aging and Alzheimer's Mouse Brain: Implication for Bioenergetic Intervention

We previously demonstrated that mitochondrial bioenergetic deficits in the female brain accompanied reproductive senescence and was accompanied by a shift from an aerobic glycolytic to a ketogenic phenotype. Herein, we investigated the relationship between systems of fuel supply, transport and mitochondrial metabolic enzyme expression/activity during aging (3–15 months) in the hippocampus of nontransgenic (nonTg) background and 3xTgAD female mice. Results indicate that during female brain aging, both nonTg and 3xTgAD brains undergo significant decline in glucose transport, as detected by FDG-microPET, between 6–9 months of age just prior to the transition into reproductive senescence. The deficit in brain metabolism was sustained thereafter. Decline in glucose transport coincided with significant decline in neuronal glucose transporter expression and hexokinase activity with a concomitant rise in phosphorylated/inactivated pyruvate dehydrogenase. Lactate utilization declined in parallel to the decline in glucose transport suggesting lactate did not serve as an alternative fuel. An adaptive response in the nonTg hippocampus was a shift to transport and utilization of ketone bodies as an alternative fuel. In the 3xTgAD brain, utilization of ketone bodies as an alternative fuel was evident at the earliest age investigated and declined thereafter. The 3xTgAD adaptive response was to substantially increase monocarboxylate transporters in neurons while decreasing their expression at the BBB and in astrocytes. Collectively, these data indicate that the earliest change in the metabolic system of the aging female brain is the decline in neuronal glucose transport and metabolism followed by decline in mitochondrial function. The adaptive shift to the ketogenic system as an alternative fuel coincided with decline in mitochondrial function. Translationally, these data provide insights into the earliest events in bioenergetic aging of the female brain and provide potential targets for preventing shifts to less efficient bioenergetic fuels and transition to the ketogenic phenotype of the Alzheimer's brain.

Human BDH2, an anti-apoptosis factor, is a novel poor prognostic factor for de novo cytogenetically normal acute myeloid leukemia

BackgroundThe relevance of recurrent molecular abnormalities in cytogenetically normal (CN) acute myeloid leukemia (AML) was recently acknowledged by the inclusion of molecular markers such as NPM1, FLT3, and CEBPA as a complement to cytogenetic information within both the World Health Organization and the European Leukemia Net classifications. Mitochondrial metabolism is different in cancer and normal cells. A novel cytosolic type 2-hydroxybutyrate dehydrogenase, BDH2, originally named DHRS6, plays a physiological role in the cytosolic utilization of ketone bodies, which can subsequently enter mitochondria and the tricarboxylic acid cycle. Moreover, BDH2 catalyzes the production of 2, 3-DHBA during enterobactin biosynthesis and participates in 24p3 (LCN2)-mediated iron transport and apoptosis.ResultsWe observed that BDH2 expression is an independent poor prognostic factor for CN-AML, with an anti-apoptotic role. Patients with high BDH2 expression have relatively shorter overall survival (P = 0.007) and a low complete response rate (P = 0.032). BDH2-knockdown (BDH2-KD) in THP1 and HL60 cells increased the apoptosis rate under reactive oxygen species stimulation. Decrease inducible survivin, a member of the inhibitors of apoptosis family, but not members of the Bcl-2 family, induced apoptosis via a caspase-3-independent pathway upon BDH2-KD.ConclusionsBDH2 is a novel independent poor prognostic marker for CN-AML, with the role of anti-apoptosis, through surviving.

The role of ketone body‐utilizing enzyme, acetoacetyl‐CoA synthetase, in lipogenic tissue

Acetoacetyl‐CoA synthetase (AACS) is a ketone body‐utilizing enzyme for the synthesis of cholesterol and fatty acids and is highly expressed in the lipogenic tissues. In this study, we investigated the regulation of AACS in liver, adipocyte and neuron to clarify the physiological role of AACS. ChIP assay and knockdown experiments showed that AACS is mainly regulated by SREBP‐2 in the neuron and liver, and by C/EBP alpha in adipocytes. In 3T3‐L1 adipocytes, treatment with shRNA against AACS resulted in inhibition of lipid storage and reduction of adipocyte markers, such as C/EBP alpha and PPAR gamma. In the liver, knockdown of AACS using hydrodynamics method decreased total serum cholesterol. Moreover, suppression of AACS by shRNA in primary neurons caused decreases in the expression of MAP‐2 and NeuN, which are markers of neuronal differentiation, as well as synaptopodin, a marker of spine apparatus. These results suggest that ketone body utilization via AACS is an important reaction for lipogenic cellular function.

A structural mapping of mutations causing succinyl‐CoA:3‐ketoacid CoA transferase (SCOT) deficiency

Succinyl-CoA:3-ketoacid CoA transferase (SCOT) deficiency is a rare inherited metabolic disorder of ketone metabolism, characterized by ketoacidotic episodes and often permanent ketosis. To date there are ∼20 disease-associated alleles on the OXCT1 gene that encodes the mitochondrial enzyme SCOT. SCOT catalyzes the first, rate-limiting step of ketone body utilization in peripheral tissues, by transferring a CoA moiety from succinyl-CoA to form acetoacetyl-CoA, for entry into the tricarboxylic acid cycle for energy production. We have determined the crystal structure of human SCOT, providing a molecular understanding of the reported mutations based on their potential structural effects. An interactive version of this manuscript (which may contain additional mutations appended after acceptance of this manuscript) may be found on the web address: http://www.thesgc.org/jimd/SCOT.Electronic supplementary materialThe online version of this article (doi:10.1007/s10545-013-9589-z) contains supplementary material, which is available to authorized users.

Ketogenic Diet in Advanced Cancer: A Pilot Feasibility and Safety Trial in the Veterans Affairs Cancer Patient Population

In their natural state within the body, normal cells use cellular respiration as their main source of ATP and energy. Carbohydrate deprived cells easily depend on the resulting ketone bodies for an alternative energy source. This natural evolutionary adaptation to starvation allows for survival of normal cells during times of fasting or famine. Cancer cells in contrast are defective in this respect, lacking the ability to utilize ketone bodies for energy and depend heavily on glycolysis for survival. The pancreas senses increased carbohydrate intake resulting in increased insulin secretion. Normal growth throughout the body depends on insulin, which by itself is also a potent growth factor which binds to cell membrane insulin receptors and stimulates mitosis via signal transduction and DNA synthesis, resulting in less apoptosis or tumor cell death. Consequentially, carbohydrate restriction will increase tumor cell destruction. We are conducting a pilot study to examine the safety and tolerability of the ketogenic diet KD in patients with advanced cancer within the Veteran Affairs Pittsburgh Healthcare System (VAPHS) oncology patient population.

Ketone body utilization drives tumor growth and metastasis

We have previously proposed that catabolic fibroblasts generate mitochondrial fuels (such as ketone bodies) to promote the anabolic growth of human cancer cells and their metastasic dissemination. We have termed this new paradigm “two-compartment tumor metabolism.” Here, we further tested this hypothesis by using a genetic approach. For this purpose, we generated hTERT-immortalized fibroblasts overexpressing the rate-limiting enzymes that promote ketone body production, namely BDH1 and HMGCS2. Similarly, we generated MDA-MB-231 human breast cancer cells overexpressing the key enzyme(s) that allow ketone body re-utilization, OXCT1/2 and ACAT1/2. Interestingly, our results directly show that ketogenic fibroblasts are catabolic and undergo autophagy, with a loss of caveolin-1 (Cav-1) protein expression. Moreover, ketogenic fibroblasts increase the mitochondrial mass and growth of adjacent breast cancer cells. However, most importantly, ketogenic fibroblasts also effectively promote tumor growth, without a significant increase in tumor angiogenesis. Finally, MDA-MB-231 cells overexpressing the enzyme(s) required for ketone re-utilization show dramatic increases in tumor growth and metastatic capacity. Our data provide the necessary genetic evidence that ketone body production and re-utilization drive tumor progression and metastasis. As such, ketone inhibitors should be designed as novel therapeutics to effectively treat advanced cancer patients, with tumor recurrence and metastatic disease. In summary, ketone bodies behave as onco-metabolites, and we directly show that the enzymes HMGCS2, ACAT1/2 and OXCT1/2 are bona fide metabolic oncogenes.