Clinical, Neuroimaging, and Metabolic Footprint of the Neurodevelopmental Disorder Caused by Monoallelic HK1 Variants.

Background and Objectives: Hexokinase 1 (encoded by HK1) catalyzes the first step of glycolysis, the adenosine triphosphate-dependent phosphorylation of glucose to glucose-6-phosphate. Monoallelic HK1 variants causing a neurodevelopmental disorder (NDD) have been reported in 12 individuals. Methods: We investigated clinical phenotypes, brain MRIs, and the CSF of 15 previously unpublished individuals with monoallelic HK1 variants and an NDD phenotype. Results: All individuals had recurrent variants likely causing gain-of-function, representing mutational hot spots. Eight individuals (c.1370C>T) had a developmental and epileptic encephalopathy with infantile onset and virtually no development. Of the other 7 individuals (n = 6: c.1334C>T; n = 1: c.1240G>A), 3 adults showed a biphasic course of disease with a mild static encephalopathy since early childhood and an unanticipated progressive deterioration with, e.g., movement disorder, psychiatric disease, and stroke-like episodes, epilepsy, starting in adulthood. Individuals who clinically presented in the first months of life had (near)-normal initial neuroimaging and severe cerebral atrophy during follow-up. In older children and adults, we noted progressive involvement of basal ganglia including Leigh-like MRI patterns and cerebellar atrophy, with remarkable intraindividual variability. The CSF glucose and the CSF/blood glucose ratio were below the 5th percentile of normal in almost all CSF samples, while blood glucose was unremarkable. This biomarker profile resembles glucose transporter type 1 deficiency syndrome; however, in HK1-related NDD, CSF lactate was significantly increased in all patients resulting in a substantially different biomarker profile. Discussion: Genotype-phenotype correlations appear to exist for HK1 variants and can aid in counseling. A CSF biomarker profile with low glucose, low CSF/blood glucose, and high CSF lactate may point toward monoallelic HK1 variants causing an NDD. This can help in variant interpretation and may aid in understanding the pathomechanism. We hypothesize that progressive intoxication and/or ongoing energy deficiency lead to the clinical phenotypes and progressive neuroimaging findings.

Triple Therapy with Metformin, Ketogenic Diet, and Metronomic Cyclophosphamide Reduced Tumor Growth in MYCN-Amplified Neuroblastoma Xenografts.

Neuroblastoma (NB) is a childhood cancer in which amplification of the MYCN gene is the most acknowledged marker of poor prognosis. MYCN-amplified NB cells rely on both glycolysis and mitochondrial oxidative phosphorylation (OXPHOS) for energy production. Previously, we demonstrated that a ketogenic diet (KD) combined with metronomic cyclophosphamide (CP) delayed tumor growth in MYCN-amplified NB xenografts. The anti-diabetic drug metformin (MET) also targets complex I of the OXPHOS system. Therefore, MET-induced disruptions of mitochondrial respiration may enhance the anti-tumor effect of CP when combined with a KD. In this study, we found that MET decreased cell proliferation and mitochondrial respiration in MYCN-amplified NB cell lines, while the combination of KD, MET, and low-dose CP (triple therapy) also reduced tumor growth and improved survival in vivo in MYCN-amplified NB xenografts. Gene ontology enrichment analysis revealed that this triple therapy had the greatest effect on the transcription of genes involved in fatty acid ß-oxidation, which was supported by the increased protein expression of CPT1A, a key mitochondrial fatty acid transporter. We suspect that alterations to ß-oxidation alongside the inhibition of complex I may hamper mitochondrial energy production, thus explaining these augmented anti-tumor effects, suggesting that the combination of MET and KD is an effective adjuvant therapy to CP in MYCN-amplified NB xenografts.

Galanin System in the Human Bile Duct and Perihilar Cholangiocarcinoma.

BACKGROUND: Perihilar cholangiocarcinoma (pCCA) is characterised by poor outcomes. Early diagnosis is essential for patient survival. The peptide galanin (GAL) and its receptors GAL1-3 are expressed in various tumours. Detailed characterisation of the GAL system in pCCA is lacking. Our study sought to characterise GAL and GAL1-3 receptor (GAL1-3-R) expression in the healthy human bile duct, in cholestasis and pCCA. METHODS: Immunohistochemical staining was performed in healthy controls (n = 5) and in the peritumoural tissues (with and without cholestasis) (n = 20) and tumour tissues of pCCA patients (n = 33) using validated antibodies. The score values of GAL and GAL1-3-R expression were calculated and statistically evaluated. RESULTS: GAL and GAL1-R were expressed in various bile duct cell types. GAL2-R was only slightly but still expressed in almost all the examined tissues, and GAL3-R specifically in cholangiocytes and capillaries. In a small pCCA patient cohort (n = 18), high GAL expression correlated with good survival, whereas high GAL3-R correlated with poor survival. CONCLUSIONS: Our in-depth characterisation of the GAL system in the healthy human biliary duct and pCCA in a small patient cohort revealed that GAL and GAL3-R expression in tumour cells of pCCA patients could potentially represent suitable biomarkers for survival.

Ageing is associated with a reduction in markers of mitochondrial energy metabolism in the human epidermis.

The decline of mitochondrial function throughout the lifespan is directly linked to the development of ageing phenotypes of the skin. Here, we assessed alterations in markers of epidermal mitochondrial energy metabolism as a function of skin age. Human skin samples from distinct anatomical regions were obtained during routine dermatological surgery from 21 young (27.6 ± 1.71 year) and 22 old (76.2 ± 1.73 year) donors. Sections of skin samples were analysed by immunohistochemistry for mitochondrial subunits of each electron transport chain complex (I-V)/oxidative phosphorylation (OXPHOS), as well as proteins serving as a marker of mitochondrial mass (VDAC1) and the regulation of DNA transcription (TFAM). Staining intensities of ATP5F1A (comprising complex V) and TFAM in the epidermis of older subjects were significantly decreased compared with younger donors. Moreover, these effects were independent of UV exposure of the stained skin section. Overall, we demonstrate that ageing is associated with reduced protein levels of complex V of the mitochondrial respiratory chain and TFAM. These alterations may impair essential mitochondrial functions, exacerbating the cutaneous ageing process.

Genotypic and phenotypic spectrum of infantile liver failure due to pathogenic TRMU variants.

PURPOSE: This study aimed to define the genotypic and phenotypic spectrum of reversible acute liver failure (ALF) of infancy resulting from biallelic pathogenic TRMU variants and determine the role of cysteine supplementation in its treatment. METHODS: Individuals with biallelic (likely) pathogenic variants in TRMU were studied within an international retrospective collection of de-identified patient data. RESULTS: In 62 individuals, including 30 previously unreported cases, we described 47 (likely) pathogenic TRMU variants, of which 17 were novel, and 1 intragenic deletion. Of these 62 individuals, 42 were alive at a median age of 6.8 (0.6-22) years after a median follow-up of 3.6 (0.1-22) years. The most frequent finding, occurring in all but 2 individuals, was liver involvement. ALF occurred only in the first year of life and was reported in 43 of 62 individuals; 11 of whom received liver transplantation. Loss-of-function TRMU variants were associated with poor survival. Supplementation with at least 1 cysteine source, typically N-acetylcysteine, improved survival significantly. Neurodevelopmental delay was observed in 11 individuals and persisted in 4 of the survivors, but we were unable to determine whether this was a primary or a secondary consequence of TRMU deficiency. CONCLUSION: In most patients, TRMU-associated ALF was a transient, reversible disease and cysteine supplementation improved survival.

Hydrogen Sulfide Metabolizing Enzymes in the Intestinal Mucosa in Pediatric and Adult Inflammatory Bowel Disease.

Hydrogen sulfide (H2S) is a toxic gas that has important regulatory functions. In the colon, H2S can be produced and detoxified endogenously. Both too little and too much H2S exposure are associated with inflammatory bowel disease (IBD), a chronic intestinal disease mainly classified as Crohn's disease (CD) and ulcerative colitis (UC). As the pathogenesis of IBD remains elusive, this study's aim was to investigate potential differences in the expression of H2S-metabolizing enzymes in normal aging and IBD. Intestinal mucosal biopsies of 25 adults and 22 children with IBD along with those of 26 healthy controls were stained immunohistochemically for cystathionine-γ-lyase (CSE), 3-mercapto-sulfurtransferase (3-MST), ethylmalonic encephalopathy 1 protein (ETHE1), sulfide:quinone oxidoreductase (SQOR) and thiosulfate sulfurtransferase (TST). Expression levels were calculated by multiplication of the staining intensity and percentage of positively stained cells. Healthy adults showed an overall trend towards lower expression of H2S-metabolizing enzymes than healthy children. Adults with IBD also tended to have lower expression compared to controls. A similar trend was seen in the enzyme expression of children with IBD compared to controls. These results indicate an age-related decrease in the expression of H2S-metabolizing enzymes and a dysfunctional H2S metabolism in IBD, which was less pronounced in children.

Ketogenic diets slow melanoma growth in vivo regardless of tumor genetics and metabolic plasticity.

BACKGROUND: Growing evidence supports the use of low-carbohydrate/high-fat ketogenic diets as an adjunctive cancer therapy. However, it is unclear which genetic, metabolic, or immunological factors contribute to the beneficial effect of ketogenic diets. Therefore, we investigated the effect of ketogenic diets on the progression and metabolism of genetically and metabolically heterogeneous melanoma xenografts, as well as on the development of melanoma metastases in mice with a functional immune system. METHODS: Mice bearing BRAF mutant, NRAS mutant, and wild-type melanoma xenografts as well as mice bearing highly metastatic melanoma allografts were fed with a control diet or ketogenic diets, differing in their triglyceride composition, to evaluate the effect of ketogenic diets on tumor growth and metastasis. We performed an in-depth targeted metabolomics analysis in plasma and xenografts to elucidate potential antitumor mechanisms in vivo. RESULTS: We show that ketogenic diets effectively reduced tumor growth in immunocompromised mice bearing genetically and metabolically heterogeneous human melanoma xenografts. Furthermore, the ketogenic diets exerted a metastasis-reducing effect in the immunocompetent syngeneic melanoma mouse model. Targeted analysis of plasma and tumor metabolomes revealed that ketogenic diets induced distinct changes in amino acid metabolism. Interestingly, ketogenic diets reduced the levels of alpha-amino adipic acid, a biomarker of cancer, in circulation to levels observed in tumor-free mice. Additionally, alpha-amino adipic acid was reduced in xenografts by ketogenic diets. Moreover, the ketogenic diets increased sphingomyelin levels in plasma and the hydroxylation of sphingomyelins and acylcarnitines in tumors. CONCLUSIONS: Ketogenic diets induced antitumor effects toward melanoma regardless of the tumors´ genetic background, its metabolic signature, and the host immune status. Moreover, ketogenic diets simultaneously affected multiple metabolic pathways to create an unfavorable environment for melanoma cell proliferation, supporting their potential as a complementary nutritional approach to melanoma therapy.

Role of Energy Metabolism and Mitochondrial Function in Inflammatory Bowel Disease.

Inflammatory bowel disease (IBD) is a chronic recurring inflammation of the intestine which can be debilitating for those with intractable disease. However, the etiopathogenesis of inflammatory bowel disorders remains to be solved. The hypothesis that mitochondrial dysfunction is a crucial factor in the disease process is being validated by an increasing number of recent studies. Thus mitochondrial alteration in conjunction with previously identified genetic predisposition, changes in the immune response, altered gut microbiota, and environmental factors (eg, diet, smoking, and lifestyle) are all posited to contribute to IBD. The implicated factors seem to affect mitochondrial function or are influenced by mitochondrial dysfunction, which explains many of the hallmarks of the disease. This review summarizes the results of studies reporting links between mitochondria and IBD that were available on PubMed through March 2021. The aim of this review is to give an overview of the current understanding of the role of mitochondria in the pathogenesis of IBD.

We address the effect of energy metabolism and mitochondrial function on the pathogenesis of inflammatory bowel disease. Because many studies on this topic have been published recently, it is important to give an overview of the results of that work.

Expression of Oxidative Phosphorylation Complexes and Mitochondrial Mass in Pediatric and Adult Inflammatory Bowel Disease.

INTRODUCTION: Inflammatory bowel disease (IBD), which includes Crohn's disease (CD) and ulcerative colitis (UC), is a multifactorial intestinal disorder but its precise etiology remains elusive. As the cells of the intestinal mucosa have high energy demands, mitochondria may play a role in IBD pathogenesis. The present study is aimed at evaluating the expression levels of mitochondrial oxidative phosphorylation (OXPHOS) complexes in IBD. Material and Methods. 286 intestinal biopsy samples from the terminal ileum, ascending colon, and rectum from 124 probands (34 CD, 33 UC, and 57 controls) were stained immunohistochemically for all five OXPHOS complexes and the voltage-dependent anion-selective channel 1 protein (VDAC1 or porin). Expression levels were compared in multivariate models including disease stage (CD and UC compared to controls) and age (pediatric/adult). RESULTS: Analysis of the terminal ileum of CD patients revealed a significant reduction of complex II compared to controls, and a trend to lower levels was evident for VDAC1 and the other OXPHOS complexes except complex III. A similar pattern was found in the rectum of UC patients: VDAC1, complex I, complex II, and complex IV were all significantly reduced, and complex III and V showed a trend to lower levels. Reductions were more prominent in older patients compared to pediatric patients and more marked in UC than CD. CONCLUSION: A reduced mitochondrial mass is present in UC and CD compared to controls. This is potentially a result of alterations of mitochondrial biogenesis or mitophagy. Reductions were more pronounced in older patients compared to pediatric patients, and more prominent in UC than CD. Complex I and II are more severely compromised than the other OXPHOS complexes. This has potential therapeutic implications, since treatments boosting biogenesis or influencing mitophagy could be beneficial for IBD treatment. Additionally, substances specifically stimulating complex I activity should be tested in IBD treatment.

Mutations in HID1 Cause Syndromic Infantile Encephalopathy and Hypopituitarism.

OBJECTIVE: Precursors of peptide hormones undergo posttranslational modifications within the trans-Golgi network (TGN). Dysfunction of proteins involved at different steps of this process cause several complex syndromes affecting the central nervous system (CNS). We aimed to clarify the genetic cause in a group of patients characterized by hypopituitarism in combination with brain atrophy, thin corpus callosum, severe developmental delay, visual impairment, and epilepsy. METHODS: Whole exome sequencing was performed in seven individuals of six unrelated families with these features. Postmortem histopathological and HID1 expression analysis of brain tissue and pituitary gland were conducted in one patient. Functional consequences of the homozygous HID1 variant p.R433W were investigated by Seahorse XF Assay in fibroblasts of two patients. RESULTS: Bi-allelic variants in the gene HID1 domain-containing protein 1 (HID1) were identified in all patients. Postmortem examination confirmed cerebral atrophy with enlarged lateral ventricles. Markedly reduced expression of pituitary hormones was found in pituitary gland tissue. Colocalization of HID1 protein with the TGN was not altered in fibroblasts of patients compared to controls, while the extracellular acidification rate upon stimulation with potassium chloride was significantly reduced in patient fibroblasts compared to controls. INTERPRETATION: Our findings indicate that mutations in HID1 cause an early infantile encephalopathy with hypopituitarism as the leading presentation, and expand the list of syndromic CNS diseases caused by interference of TGN function. ANN NEUROL 2021;90:149-164.

Targeted Metabolomics Identifies Plasma Biomarkers in Mice with Metabolically Heterogeneous Melanoma Xenografts.

Melanomas are genetically and metabolically heterogeneous, which influences therapeutic efficacy and contributes to the development of treatment resistance in patients with metastatic disease. Metabolite phenotyping helps to better understand complex metabolic diseases, such as melanoma, and facilitates the development of novel therapies. Our aim was to characterize the tumor and plasma metabolomes of mice bearing genetically different melanoma xenografts. We engrafted the human melanoma cell lines A375 (BRAF mutant), WM47 (BRAF mutant), WM3000 (NRAS mutant), and WM3311 (BRAF, NRAS, NF1 triple-wildtype) and performed a broad-spectrum targeted metabolomics analysis of tumor and plasma samples obtained from melanoma-bearing mice as well as plasma samples from healthy control mice. Differences in ceramide and phosphatidylcholine species were observed between melanoma subtypes irrespective of the genetic driver mutation. Furthermore, beta-alanine metabolism differed between melanoma subtypes and was significantly enriched in plasma from melanoma-bearing mice compared to healthy mice. Moreover, we identified beta-alanine, p-cresol sulfate, sarcosine, tiglylcarnitine, two dihexosylceramides, and one phosphatidylcholine as potential melanoma biomarkers in plasma. The present data reflect the metabolic heterogeneity of melanomas but also suggest a diagnostic biomarker signature for melanoma screening.

The switch in the diagnosis of mitochondrial diseases from the classical 'function first' to the NGS-based 'genetics first' diagnostic era.

The knowledge of causes and pathophysiology of mitochondrial diseases has increased exponentially in the last four decades. Recently, due to the decreased costs of new sequencing technologies (exome and whole genome sequencing), these technologies were applied more and more in clinical routine. The traditional diagnostic approach ('biopsy first') of evaluating the patient and his body fluids and the analysis of enzymes of the oxidative phosphorylation system in skeletal muscle with subsequent Sanger sequencing of single candidate genes ('from function to gene') were replaced by next generation sequencing techniques with a diagnostic yield of >40%. In this 'genetics first' approach, the detection of new candidate genes necessitates often functional evaluations ('from gene to function') leading to reverse phenotyping of affected individuals. The new genetic era has offered a clear new challenge for the responsibility of the diagnostic centres: the interplay of clinicians, geneticists and functional biochemists is a prerequisite for a validated diagnosis. It becomes evident that expanded diagnostics builds an interface to research. Only competence centres with high numbers of patients, clinical and diagnostic experience and exchange of knowledge with other comparable units can fulfil all those requirements.

Targeting Mitochondria in Melanoma.

Drastically elevated glycolytic activity is a prominent metabolic feature of cancer cells. Until recently it was thought that tumor cells shift their entire energy production from oxidative phosphorylation (OXPHOS) to glycolysis. However, new evidence indicates that many cancer cells still have functional OXPHOS, despite their increased reliance on glycolysis. Growing pre-clinical and clinical evidence suggests that targeting mitochondrial metabolism has anti-cancer effects. Here, we analyzed mitochondrial respiration and the amount and activity of OXPHOS complexes in four melanoma cell lines and normal human dermal fibroblasts (HDFs) by Seahorse real-time cell metabolic analysis, immunoblotting, and spectrophotometry. We also tested three clinically approved antibiotics, one anti-parasitic drug (pyrvinium pamoate), and a novel anti-cancer agent (ONC212) for effects on mitochondrial respiration and proliferation of melanoma cells and HDFs. We found that three of the four melanoma cell lines have elevated glycolysis as well as OXPHOS, but contain dysfunctional mitochondria. The antibiotics produced different effects on the melanoma cells and HDFs. The anti-parasitic drug strongly inhibited respiration and proliferation of both the melanoma cells and HDFs. ONC212 reduced respiration in melanoma cells and HDFs, and inhibited the proliferation of melanoma cells. Our findings highlight ONC212 as a promising drug for targeting mitochondrial respiration in cancer.

Age-Related Deterioration of Mitochondrial Function in the Intestine.

Aging is an important and inevitable biological process in human life, associated with the onset of chronic disease and death. The mechanisms behind aging remain unclear. However, changes in mitochondrial function and structure, including reduced activity of the mitochondrial respiratory chain and increased production of reactive oxygen species-thus oxidative damage-are believed to play a major role. Mitochondria are the main source of cellular energy, producing adenosine triphosphate (ATP) via oxidative phosphorylation. Accumulation of damaged cellular components reduces a body's capacity to preserve tissue homeostasis and affects biological aging and all age-related chronic conditions. This includes the onset and progression of classic degenerative diseases such as cardiovascular disease, kidney failure, neurodegenerative diseases, and cancer. Clinical manifestations of intestinal disorders, such as mucosal barrier dysfunction, intestinal dysmotility, and chronic obstipation, are highly prevalent in the elderly population and have been shown to be associated with an age-dependent decline of mitochondrial function. This review summarizes our current understanding of the role of mitochondrial dysfunction in intestinal aging.

Metabolic reprogramming related to whole-chromosome instability in models for Hürthle cell carcinoma.

Hürthle cell carcinoma (HCC) is a recurrent subtype of non-medullary thyroid cancer. HCC is characterized by profound whole-chromosome instability (w-CIN), resulting in a near-homozygous genome (NHG), a phenomenon recently attributed to reactive oxygen species (ROS) generated during mitosis by malfunctioning mitochondria. We studied shared metabolic traits during standard and glucose-depleted cell culture in thyroid cancer cell lines (TCCLs), with or without a NHG, using quantitative analysis of extra and intracellular metabolites and ROS production following inhibition of complex III with antimycin A. We found that the XTC.UC1 and FTC-236 cell lines (both NHG) are functionally impaired in complex I and produce significantly more superoxide radicals than SW579 and BHP 2-7 (non-NHG) after challenge with antimycin A. FTC-236 showed the lowest levels of glutathione and SOD2. XTC.UC1 and FTC-236 both exhibited reduced glycolytic activity and utilization of alternative sources to meet energy demands. Both cell lines also shared low levels of α-ketoglutarate and high levels of creatine, phosphocreatine, uridine diphosphate-N-acetylglucosamine, pyruvate and acetylcarnitine. Furthermore, the metabolism of XTC.UC1 was skewed towards the de novo synthesis of aspartate, an effect that persisted even in glucose-free media, pointing to reductive carboxylation. Our data suggests that metabolic reprogramming and a subtle balance between ROS generation and scavenging/conversion of intermediates may be involved in ROS-induced w-CIN in HCC and possibly also in rare cases of follicular thyroid cancer showing a NHG.

From old to new - Repurposing drugs to target mitochondrial energy metabolism in cancer.

Although we have entered the era of personalized medicine and tailored therapies, drugs that target a large variety of cancers regardless of individual patient differences would be a major advance nonetheless. This review article summarizes current concepts and therapeutic opportunities in the area of targeting aerobic mitochondrial energy metabolism in cancer. Old drugs previously used for diseases other than cancer, such as antibiotics and antidiabetics, have the potential to inhibit the growth of various tumor entities. Many drugs are reported to influence mitochondrial metabolism. However, here we consider only those drugs which predominantly inhibit oxidative phosphorylation.

Ketogenic diet in the treatment of cancer - Where do we stand?

BACKGROUND: Cancer is one of the greatest public health challenges worldwide, and we still lack complementary approaches to significantly enhance the efficacy of standard anticancer therapies. The ketogenic diet, a high-fat, low-carbohydrate diet with adequate amounts of protein, appears to sensitize most cancers to standard treatment by exploiting the reprogramed metabolism of cancer cells, making the diet a promising candidate as an adjuvant cancer therapy. SCOPE OF REVIEW: To critically evaluate available preclinical and clinical evidence regarding the ketogenic diet in the context of cancer therapy. Furthermore, we highlight important mechanisms that could explain the potential antitumor effects of the ketogenic diet. MAJOR CONCLUSIONS: The ketogenic diet probably creates an unfavorable metabolic environment for cancer cells and thus can be regarded as a promising adjuvant as a patient-specific multifactorial therapy. The majority of preclinical and several clinical studies argue for the use of the ketogenic diet in combination with standard therapies based on its potential to enhance the antitumor effects of classic chemo- and radiotherapy, its overall good safety and tolerability and increase in quality of life. However, to further elucidate the mechanisms of the ketogenic diet as a therapy and evaluate its application in clinical practice, more molecular studies as well as uniformly controlled clinical trials are needed.

Targeting L-Lactate Metabolism to Overcome Resistance to Immune Therapy of Melanoma and Other Tumor Entities.

Although immunotherapy plays a significant role in tumor therapy, its efficacy is impaired by an immunosuppressive tumor microenvironment. A molecule that contributes to the protumor microenvironment is the metabolic product lactate. Lactate is produced in large amounts by cancer cells in response to either hypoxia or pseudohypoxia, and its presence in excess alters the normal functioning of immune cells. A key enzyme involved in lactate metabolism is lactate dehydrogenase (LDH). Elevated baseline LDH serum levels are associated with poor outcomes of current anticancer (immune) therapies, especially in patients with melanoma. Therefore, targeting LDH and other molecules involved in lactate metabolism might improve the efficacy of immune therapies. This review summarizes current knowledge about lactate metabolism and its role in the tumor microenvironment. Based on that information, we develop a rationale for deploying drugs that target lactate metabolism in combination with immune checkpoint inhibitors to overcome lactate-mediated immune escape of tumor cells.

Untargeted Metabolomics Reveals Molecular Effects of Ketogenic Diet on Healthy and Tumor Xenograft Mouse Models.

The application of ketogenic diet (KD) (high fat/low carbohydrate/adequate protein) as an auxiliary cancer therapy is a field of growing attention. KD provides sufficient energy supply for healthy cells, while possibly impairing energy production in highly glycolytic tumor cells. Moreover, KD regulates insulin and tumor related growth factors (like insulin growth factor-1, IGF-1). In order to provide molecular evidence for the proposed additional inhibition of tumor growth when combining chemotherapy with KD, we applied untargeted quantitative metabolome analysis on a spontaneous breast cancer xenograft mouse model, using MDA-MB-468 cells. Healthy mice and mice bearing breast cancer xenografts and receiving cyclophosphamide chemotherapy were compared after treatment with control diet and KD. Metabolomic profiling was performed on plasma samples, applying high-performance liquid chromatography coupled to tandem mass spectrometry. Statistical analysis revealed metabolic fingerprints comprising numerous significantly regulated features in the group of mice bearing breast cancer. This fingerprint disappeared after treatment with KD, resulting in recovery to the metabolic status observed in healthy mice receiving control diet. Moreover, amino acid metabolism as well as fatty acid transport were found to be affected by both the tumor and the applied KD. Our results provide clear evidence of a significant molecular effect of adjuvant KD in the context of tumor growth inhibition and suggest additional mechanisms of tumor suppression beyond the proposed constrain in energy supply of tumor cells.

Severe Deoxyguanosine Kinase Deficiency in Austria: A 6-Patient Series.

Mutations in the nuclear gene DGUOK, encoding deoxyguanosine kinase, cause an infantile hepatocerebral type of mitochondrial depletion syndrome (MDS). We report 6 MDS patients harboring bi-allelic DGUOK mutations, of which 3 are novel, including a large intragenic Austrian founder deletion. One patient was diagnosed with hepatocellular carcinoma aged 6 months, supporting a link between mitochondrial DNA depletion and tumorigenesis; liver transplantation proved beneficial with regard to both tumor treatment and psychomotor development.