Imperial College London

ProfessorHectorKeun

Faculty of MedicineDepartment of Surgery & Cancer

Professor of Biochemistry
 
 
 
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Contact

 

+44 (0)20 7594 3161h.keun

 
 
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Location

 

officesInstitute of Reproductive and Developmental BiologyHammersmith Campus

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Summary

 

Publications

Publication Type
Year
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149 results found

Georgiadis P, Gavriil M, Rantakokko P, Ladoukakis E, Botsivali M, Kelly RS, Bergdahl IA, Kiviranta H, Vermeulen RCH, Spaeth F, Hebbels DGAJ, Kleinjans JCS, de Kok TMCM, Palli D, Vineis P, Kyrtopoulos SA, EnviroGenomarkers consortiumet al., 2019, DNA methylation profiling implicates exposure to PCBs in the pathogenesis of B-cell chronic lymphocytic leukemia, Environment International, Vol: 126, Pages: 24-36, ISSN: 0160-4120

OBJECTIVES: To characterize the impact of PCB exposure on DNA methylation in peripheral blood leucocytes and to evaluate the corresponding changes in relation to possible health effects, with a focus on B-cell lymphoma. METHODS: We conducted an epigenome-wide association study on 611 adults free of diagnosed disease, living in Italy and Sweden, in whom we also measured plasma concentrations of 6 PCB congeners, DDE and hexachlorobenzene. RESULTS: We identified 650 CpG sites whose methylation correlates strongly (FDR < 0.01) with plasma concentrations of at least one PCB congener. Stronger effects were observed in males and in Sweden. This epigenetic exposure profile shows extensive and highly statistically significant overlaps with published profiles associated with the risk of future B-cell chronic lymphocytic leukemia (CLL) as well as with clinical CLL (38 and 28 CpG sites, respectively). For all these sites, the methylation changes were in the same direction for increasing exposure and for higher disease risk or clinical disease status, suggesting an etiological link between exposure and CLL. Mediation analysis reinforced the suggestion of a causal link between exposure, changes in DNA methylation and disease. Disease connectivity analysis identified multiple additional diseases associated with differentially methylated genes, including melanoma for which an etiological link with PCB exposure is established, as well as developmental and neurological diseases for which there is corresponding epidemiological evidence. Differentially methylated genes include many homeobox genes, suggesting that PCBs target stem cells. Furthermore, numerous polycomb protein target genes were hypermethylated with increasing exposure, an effect known to constitute an early marker of carcinogenesis. CONCLUSIONS: This study provides mechanistic evidence in support of a link between exposure to PCBs and the etiology of CLL and underlines the utility of omic profiling in the evaluation o

Journal article

Allen SP, Hall B, Castelli LM, Francis L, Woof R, Siskos AP, Kouloura E, Gray E, Thompson AG, Talbot K, Higginbottom A, Myszczynska M, Allen CF, Stopford MJ, Hemingway J, Bauer CS, Webster CP, De Vos KJ, Turner MR, Keun HC, Hautbergue GM, Ferraiuolo L, Shaw PJet al., 2019, Astrocyte adenosine deaminase loss increases motor neuron toxicity in amyotrophic lateral sclerosis, Brain, Vol: 142, Pages: 586-605, ISSN: 1460-2156

As clinical evidence supports a negative impact of dysfunctional energy metabolism on the disease progression in amyotrophic lateral sclerosis, it is vital to understand how the energy metabolic pathways are altered and whether they can be restored to slow disease progression. Possible approaches include increasing or rerouting catabolism of alternative fuel sources to supplement the glycolytic and mitochondrial pathways such as glycogen, ketone bodies and nucleosides. To analyse the basis of the catabolic defect in amyotrophic lateral sclerosis we used a novel phenotypic metabolic array. We profiled fibroblasts and induced neuronal progenitor-derived human induced astrocytes from C9orf72 amyotrophic lateral sclerosis patients compared to normal controls, measuring the rates of production of reduced nicotinamide adenine dinucleotides from 91 potential energy substrates. This approach shows for the first time that C9orf72 human induced astrocytes and fibroblasts have an adenosine to inosine deamination defect caused by reduction of adenosine deaminase, which is also observed in induced astrocytes from sporadic patients. Patient-derived induced astrocyte lines were more susceptible to adenosine-induced toxicity, which could be mimicked by inhibiting adenosine deaminase in control lines. Furthermore, adenosine deaminase inhibition in control induced astrocytes led to increased motor neuron toxicity in co-cultures, similar to the levels observed with patient derived induced astrocytes. Bypassing metabolically the adenosine deaminase defect by inosine supplementation was beneficial bioenergetically in vitro, increasing glycolytic energy output and leading to an increase in motor neuron survival in co-cultures with induced astrocytes. Inosine supplementation, in combination with modulation of the level of adenosine deaminase may represent a beneficial therapeutic approach to evaluate in patients with amyotrophic lateral sclerosis.

Journal article

Behrends V, Giskeodegard GF, Bravo-Santano N, Letek M, Keun HCet al., 2019, Acetaminophen cytotoxicity in HepG2 cells is associated with a decoupling of glycolysis from the TCA cycle, loss of NADPH production, and suppression of anabolism, Archives of Toxicology, Vol: 93, Pages: 341-353, ISSN: 0340-5761

Acetaminophen (APAP) is one of the most commonly used analgesics worldwide, and overdoses are associated with lactic acidosis, hepatocyte toxicity, and acute liver failure due to oxidative stress and mitochondrial dysfunction. Hepatoma cell lines typically lack the CYP450 activity to generate the reactive metabolite of APAP observed in vivo, but are still subject to APAP cytotoxicity. In this study, we employed metabolic profiling and isotope labelling approaches to investigate the metabolic impact of acute exposure to cytotoxic doses of APAP on the widely used HepG2 cell model. We found that APAP exposure leads to limited cellular death and substantial growth inhibition. Metabolically, we observed an up-regulation of glycolysis and lactate production with a concomitant reduction in carbon from glucose entering the pentose-phosphate pathway and the TCA cycle. This was accompanied by a depletion of cellular NADPH and a reduction in the de novo synthesis of fatty acids and the amino acids serine and glycine. These events were not associated with lower reduced glutathione levels and no glutathione conjugates were seen in cell extracts. Co-treatment with a specific inhibitor of the lactate/H+ transporter MCT1, AZD3965, led to increased apoptosis in APAP-treated cells, suggesting that lactate accumulation could be a cause of cell death in this model. In conclusion, we show that APAP toxicity in HepG2 cells is largely independent of oxidative stress, and is linked instead to a decoupling of glycolysis from the TCA cycle, lactic acidosis, reduced NADPH production, and subsequent suppression of the anabolic pathways required for rapid growth.

Journal article

Parzych K, Saavedra Garcia P, Valbuena G, Alsadah HAH, Robinson M, Penfold L, Kuzeva D, Ruiz Tellez A, Loaiza S, Holzmann V, Caputo V, Johnson DC, Kaiser MF, Karadimitris A, Lam E, Chevet E, Feldhahn N, Keun H, Auner Het al., 2019, The coordinated action of VCP/p97 and GCN2 regulates cancer cell metabolism and proteostasis during nutrient limitation, Oncogene, ISSN: 0950-9232

VCP/p97 regulates numerous cellular functions by mediating protein degradation through its segregase activity. Its key role in governing protein homoeostasis has made VCP/p97 an appealing anticancer drug target. Here, we provide evidence that VCP/p97 acts as a regulator of cellular metabolism. We found that VCP/p97 was tied to multiple metabolic processes on the gene expression level in a diverse range of cancer cell lines and in patient-derived multiple myeloma cells. Cellular VCP/p97 dependency to maintain proteostasis was increased under conditions of glucose and glutamine limitation in a range of cancer cell lines from different tissues. Moreover, glutamine depletion led to increased VCP/p97 expression, whereas VCP/p97 inhibition perturbed metabolic processes and intracellular amino acid turnover. GCN2, an amino acid-sensing kinase, attenuated stress signalling and cell death triggered by VCP/p97 inhibition and nutrient shortages and modulated ERK activation, autophagy, and glycolytic metabolite turnover. Together, our data point to an interconnected role of VCP/p97 and GCN2 in maintaining cancer cell metabolic and protein homoeostasis.

Journal article

Limonciel A, van Breda SG, Jiang X, Tredwell GD, Wilmes A, Aschauer L, Siskos AP, Sachinidis A, Keun HC, Kopp-Schneider A, de Kok TM, Kleinjans JCS, Jennings Pet al., 2018, Persistence of epigenomic effects after recovery from repeated treatment with two nephrocarcinogens, Frontiers in Genetics, Vol: 9, ISSN: 1664-8021

The discovery of the epigenetic regulation of transcription has provided a new source of mechanistic understanding to long lasting effects of chemicals. However, this information is still seldom exploited in a toxicological context and studies of chemical effect after washout remain rare. Here we studied the effects of two nephrocarcinogens on the human proximal tubule cell line RPTEC/TERT1 using high-content mRNA microarrays coupled with miRNA, histone acetylation (HA) and DNA methylation (DM) arrays and metabolomics during a 5-day repeat-dose exposure and 3 days after washout. The mycotoxin ochratoxin A (OTA) was chosen as a model compound for its known impact on HA and DM. The foremost effect observed was the modulation of thousands of mRNAs and histones by OTA during and after exposure. In comparison, the oxidant potassium bromate (KBrO3) had a milder impact on gene expression and epigenetics. However, there was no strong correlation between epigenetic modifications and mRNA changes with OTA while with KBrO3 the gene expression data correlated better with HA for both up- and down-regulated genes. Even when focusing on the genes with persistent epigenetic modifications after washout, only half were coupled to matching changes in gene expression induced by OTA, suggesting that while OTA causes a major effect on the two epigenetic mechanisms studied, these alone cannot explain its impact on gene expression. Mechanistic analysis confirmed the known activation of Nrf2 and p53 by KBrO3, while OTA inhibited most of the same genes, and genes involved in the unfolded protein response. A few miRNAs could be linked to these effects of OTA, albeit without clear contribution of epigenetics to the modulation of the pathways at large. Metabolomics revealed disturbances in amino acid balance, energy catabolism, nucleotide metabolism and polyamine metabolism with both chemicals. In conclusion, the large impact of OTA on transcription was confirmed at the mRNA level but also with

Journal article

Haug LS, Sakhi AK, Cequier E, Casas M, Maitre L, Basagana X, Andrusaityte S, Chalkiadaki G, Chatzi L, Coen M, de Bont J, Dedele A, Ferrand J, Grazuleviciene R, Ramon Gonzalez J, Gutzkow KB, Keun H, McEachan R, Meltzer HM, Petraviciene I, Robinson O, Saulnier P-J, Slama R, Sunyer J, Urquiza J, Vafeiadi M, Wright J, Vrijheid M, Thomsen Cet al., 2018, In-utero and childhood chemical exposome in six European mother-child cohorts, Environment International, Vol: 121, Pages: 751-763, ISSN: 0160-4120

BackgroundHarmonized data describing simultaneous exposure to a large number of environmental contaminants in-utero and during childhood is currently very limited.ObjectivesTo characterize concentrations of a large number of environmental contaminants in pregnant women from Europe and their children, based on chemical analysis of biological samples from mother-child pairs.MethodsWe relied on the Early-Life Exposome project, HELIX, a collaborative project across six established population-based birth cohort studies in Europe. In 1301 subjects, biomarkers of exposure to 45 contaminants (i.e. organochlorine compounds, polybrominated diphenyl ethers, per- and polyfluoroalkyl substances, toxic and essential elements, phthalate metabolites, environmental phenols, organophosphate pesticide metabolites and cotinine) were measured in biological samples from children (6–12 years) and their mothers during pregnancy, using highly sensitive biomonitoring methods.ResultsMost of the exposure biomarkers had high detection frequencies in mothers (35 out of 45 biomarkers with >90% detected) and children (33 out of 45 biomarkers with >90% detected). Concentrations were significantly different between cohorts for all compounds, and were generally higher in maternal compared to children samples. For most of the persistent compounds the correlations between maternal and child concentrations were moderate to high (Spearman Rho > 0.35), while for most non-persistent compounds correlations were considerably lower (Spearman Rho < 0.15). For mercury, PFOS and PFOA a considerable proportion of the samples of both mothers and their children exceeded the HBM I value established by The Human Biomonitoring Commission of the German Federal Environment Agency.DiscussionAlthough not based on a representative sample, our study suggests that children across Europe are exposed to a wide range of environmental contaminants in fetal life and childhood including many with potential advers

Journal article

Maitre L, Robinson O, Martinez D, Toledano MB, Ibarluzea J, Santa Marina L, Sunyer J, Villanueva CM, Keun HC, Vrijheid M, Coen Met al., 2018, Urine metabolic signatures of multiple environmental pollutants in pregnant women - an exposome approach, Environmental Science and Technology, Vol: 52, Pages: 13469-13480, ISSN: 0013-936X

Exposure to environmental pollutants, particularly during pregnancy, can have adverse consequences on child development but little is known about the effects of pollutant mixtures on endogenous metabolism in pregnant women. We aimed to identify urinary metabolic signatures associated with low level exposure to multiple environmental pollutants in pregnant women from the INMA (INfancia y Medio Ambiente) birth cohort (Spain, N = 750). 35 chemical exposures were quantified in first trimester blood samples (organochlorine pesticides, PCBs, PFAS), in cord blood (mercury), and twice in urine at 12 and 32 weeks of pregnancy (metals, phthalates, bisphenol A). 1H nuclear magnetic resonance (NMR) metabolic profiles of urine were acquired in the same samples as pollutants. We explored associations between exposures and metabolism through an exposome-metabolome wide association scan and multivariate O2PLS modeling. Novel and reproducible associations were found across two periods of pregnancy for three nonpersistent pollutants and across two subcohorts for four of the persistent pollutants. We found novel metabolic signatures associated with arsenic exposure: TMAO and dimethylamine possibly related to gut microbial methylamine metabolism and homarine related to fish intake. Tobacco smoke exposure was related to coffee metabolism and PCBs with 3-hydroxyvaleric acid, usually released under ketoacidosis. These findings will have implications for further understanding of maternal-fetal health, and health across the life-course.

Journal article

Lau CH, Siskos AP, Maitre L, Robinson O, Athersuch TJ, Want EJ, Urquiza J, Casas M, Vafeiadi M, Roumeliotaki T, McEachan RRC, Azad R, Haug LS, Meltzer HM, Andrusaityte S, Petraviciene I, Grazuleviciene R, Thomsen C, Wright J, Slama R, Chatzi L, Vrijheid M, Keun HC, Coen Met al., 2018, Determinants of the urinary and serum metabolome in children from six European populations, BMC Medicine, Vol: 16, ISSN: 1741-7015

BackgroundEnvironment and diet in early life can affect development and health throughout the life course. Metabolic phenotyping of urine and serum represents a complementary systems-wide approach to elucidate environment–health interactions. However, large-scale metabolome studies in children combining analyses of these biological fluids are lacking. Here, we sought to characterise the major determinants of the child metabolome and to define metabolite associations with age, sex, BMI and dietary habits in European children, by exploiting a unique biobank established as part of the Human Early-Life Exposome project (http://www.projecthelix.eu).MethodsMetabolic phenotypes of matched urine and serum samples from 1192 children (aged 6–11) recruited from birth cohorts in six European countries were measured using high-throughput 1H nuclear magnetic resonance (NMR) spectroscopy and a targeted LC-MS/MS metabolomic assay (Biocrates AbsoluteIDQ p180 kit).ResultsWe identified both urinary and serum creatinine to be positively associated with age. Metabolic associations to BMI z-score included a novel association with urinary 4-deoxyerythronic acid in addition to valine, serum carnitine, short-chain acylcarnitines (C3, C5), glutamate, BCAAs, lysophosphatidylcholines (lysoPC a C14:0, lysoPC a C16:1, lysoPC a C18:1, lysoPC a C18:2) and sphingolipids (SM C16:0, SM C16:1, SM C18:1). Dietary-metabolite associations included urinary creatine and serum phosphatidylcholines (4) with meat intake, serum phosphatidylcholines (12) with fish, urinary hippurate with vegetables, and urinary proline betaine and hippurate with fruit intake. Population-specific variance (age, sex, BMI, ethnicity, dietary and country of origin) was better captured in the serum than in the urine profile; these factors explained a median of 9.0% variance amongst serum metabolites versus a median of 5.1% amongst urinary metabolites. Metabolic pathway correlations were identified, and concentrations of

Journal article

Vermeulen R, Saberi Hosnijeh F, Bodinier B, Portengen L, Liquet B, Garrido Manriquez J, Lokhorst H, Bergdahl I, Kyrtopoulos S, Johansson A-S, Georgiadis P, Melin B, Palli D, Krogh V, Panico S, Sacerdote C, Tumino R, Vineis P, Castagne RS, Chadeau Met al., 2018, Pre-diagnostic blood immune markers, incidence and progression of B-cell lymphoma and multiple myeloma; univariate and functionally-informed multivariate analyses, International Journal of Cancer, Vol: 143, Pages: 1335-1347, ISSN: 0020-7136

Recent prospective studies have shown that dysregulation of the immune system may precede the development of B-cell lymphomas (BCL) in immunocompetent individuals. However, to date, the studies were restricted to a few immune markers, which were considered separately. Using a nested case-control study within two European prospective cohorts, we measured plasma levels of 28 immune markers in samples collected a median of 6 years prior to diagnosis (range, 2.01-15.97) in 268 incident cases of BCL (including multiple myeloma) and matched controls. Linear mixed models, and Partial Least Square analyses were used to analyze the association between levels of immune marker and the incidence of BCL and its main histological subtypes, and to investigate potential biomarkers predictive of the time to diagnosis. Linear mixed modelIrrespective of the model, our analyses identified associations linking blood lower immune markerslevels of and BCL incidence. In particular, we identified growth factors, and within that family, fibroblast growth factor-2 (FGF-2,p=7.2x10-4), ) and transforming growth factor alpha (TGF-α, p=6.5x10-5) and BCL incidence.Analyses stratified by histological subtypes identified inverse associations for MM subtype including FGF-2 (p=7.8x10-7), TGF-α (p=4.08x10-5),fractalkine (p=1.12x10-3), monocyte chemotactic protein-3 (p=1.36x10-4), macrophage inflammatory protein 1-alpha (p=4.6x10-4), and vascular endothelial growth factor (p=4.23x10-5). , and vascular endothelial growth factor (VEGF), to be consistently (and inversely) associated with MM incidence. Our results also provided marginal support for already reported associations between chemokines and diffuse large B-Cell lymphoma (DLBCL), and cytokines and chronic lymphocytic leukemia (CLL). Case-only analyses showed that GM-CSF levels were consistently higher closer to diagnosis, which provides further evidence of its role in tumor progression.In conclusion, our study suggests a role of gr

Journal article

Maitre L, de Bont J, Casas M, Robinson O, Aasvang GM, Agier L, Andrušaitytė S, Ballester F, Basagaña X, Borràs E, Brochot C, Bustamante M, Carracedo A, de Castro M, Dedele A, Donaire-Gonzalez D, Estivill X, Evandt J, Fossati S, Giorgis-Allemand L, R Gonzalez J, Granum B, Grazuleviciene R, Bjerve Gützkow K, Småstuen Haug L, Hernandez-Ferrer C, Heude B, Ibarluzea J, Julvez J, Karachaliou M, Keun HC, Hjertager Krog N, Lau C-HE, Leventakou V, Lyon-Caen S, Manzano C, Mason D, McEachan R, Meltzer HM, Petraviciene I, Quentin J, Roumeliotaki T, Sabido E, Saulnier P-J, Siskos AP, Siroux V, Sunyer J, Tamayo I, Urquiza J, Vafeiadi M, van Gent D, Vives-Usano M, Waiblinger D, Warembourg C, Chatzi L, Coen M, van den Hazel P, Nieuwenhuijsen MJ, Slama R, Thomsen C, Wright J, Vrijheid Met al., 2018, Human Early Life Exposome (HELIX) study: a European population-based exposome cohort, BMJ Open, Vol: 8, ISSN: 2044-6055

Purpose Essential to exposome research is the collection of data on many environmental exposures from different domains in the same subjects. The aim of the Human Early Life Exposome (HELIX) study was to measure and describe multiple environmental exposures during early life (pregnancy and childhood) in a prospective cohort and associate these exposures with molecular omics signatures and child health outcomes. Here, we describe recruitment, measurements available and baseline data of the HELIX study populations.Participants The HELIX study represents a collaborative project across six established and ongoing longitudinal population-based birth cohort studies in six European countries (France, Greece, Lithuania, Norway, Spain and the UK). HELIX used a multilevel study design with the entire study population totalling 31 472 mother-child pairs, recruited during pregnancy, in the six existing cohorts (first level); a subcohort of 1301 mother-child pairs where biomarkers, omics signatures and child health outcomes were measured at age 6–11 years (second level) and repeat-sampling panel studies with around 150 children and 150 pregnant women aimed at collecting personal exposure data (third level).Findings to date Cohort data include urban environment, hazardous substances and lifestyle-related exposures for women during pregnancy and their offspring from birth until 6–11 years. Common, standardised protocols were used to collect biological samples, measure exposure biomarkers and omics signatures and assess child health across the six cohorts. Baseline data of the cohort show substantial variation in health outcomes and determinants between the six countries, for example, in family affluence levels, tobacco smoking, physical activity, dietary habits and prevalence of childhood obesity, asthma, allergies and attention deficit hyperactivity disorder.Future plans HELIX study results will inform on the early life exposome and its association with molecul

Journal article

Bravo-Santano N, Ellis JK, Mateos LM, Calle Y, Keun HC, Behrends V, Letek Met al., 2018, Intracellular Staphylococcus aureus Modulates Host Central Carbon Metabolism To Activate Autophagy, MSPHERE, Vol: 3, ISSN: 2379-5042

Staphylococcus aureus is a facultative intracellular pathogen that invades and replicates within many types of phagocytic and nonphagocytic cells. During intracellular infection, S. aureus is capable of subverting xenophagy and escaping to the cytosol of the host cell. Furthermore, drug-induced autophagy facilitates the intracellular replication of S. aureus, but the reasons behind this are unclear. Here, we have studied the host central carbon metabolism during S. aureus intracellular infection. We found extensive metabolic rerouting and detected several distinct metabolic changes that suggested starvation-induced autophagic flux in infected cells. These changes included increased uptake but lower intracellular levels of glucose and low abundance of several essential amino acids, as well as markedly upregulated glutaminolysis. Furthermore, we show that AMP-activated protein kinase (AMPK) and extracellular signal-regulated kinase (ERK) phosphorylation levels are significantly increased in infected cells. Interestingly, while autophagy was activated in response to S. aureus invasion, most of the autophagosomes detected in infected cells did not contain bacteria, suggesting that S. aureus induces the autophagic flux during cell invasion for energy generation and nutrient scavenging. Accordingly, AMPK inhibition halted S. aureus intracellular proliferation.

Journal article

Berger E, Delpierre C, Hosnijeh FS, Kelly-Irving M, Portengen L, Bergdahl IA, Johansson A-S, Krogh V, Palli D, Panico S, Sacerdote C, Tumino R, Kyrtopoulos SA, Vineis P, Chadeau-Hyam M, Vermeulen R, Castagne Ret al., 2018, Association between low-grade inflammation and Breast cancer and B-cell Myeloma and Non-Hodgkin Lymphoma: findings from two prospective cohorts, Scientific Reports, Vol: 8, ISSN: 2045-2322

Chronic inflammation may be involved in cancer development and progression. Using 28 inflammatory-related proteins collected from prospective blood samples from two case-control studies nested in the Italian component of the European Prospective Investigation into Cancer and nutrition (n = 261) and in the Northern Sweden Health and Disease Study (n = 402), we tested the hypothesis that an inflammatory score is associated with breast cancer (BC) and Β-cell Non-Hodgkin Lymphoma (B-cell NHL, including 68 multiple myeloma cases) onset. We modelled the relationship between this inflammatory score and the two cancers studied: (BC and B-cell NHL) using generalised linear models, and assessed, through adjustments the role of behaviours and lifestyle factors. Analyses were performed by cancer types pooling both populations, and stratified by cohorts, and time to diagnosis. Our results suggested a lower inflammatory score in B-cell NHL cases (β = −1.28, p = 0.012), and, to lesser, extent with BC (β = −0.96, p = 0.33) compared to controls, mainly driven by cancer cases diagnosed less than 6 years after enrolment. These associations were not affected by subsequent adjustments for potential intermediate confounders, notably behaviours. Sensitivity analyses indicated that our findings were not affected by the way the inflammatory score was calculated. These observations call for further studies involving larger populations, larger variety of cancer types and repeated measures of larger panel of inflammatory markers.

Journal article

Sborchia M, De Prez EG, Bienfait L, Indra R, Dracinska H, Nortier J, Stiborova M, Keun H, Arlt VMet al., 2018, Toxicogenomics changes induced by the human carcinogen aristolochic acid I in Trp53(+/+), Trp53(+/-) and Trp53(-/-) mice, Publisher: WILEY, Pages: 11-12, ISSN: 2211-5463

Conference paper

Rodrigues RM, Kollipara L, Chaudhari U, Sachinidis A, Zahedi RP, Sickmann A, Kopp-Schneider A, Jiang X, Keun H, Hengstler J, Oorts M, Annaert P, Hoeben E, Gijbels E, De Kock J, Vanhaecke T, Rogiers V, Vinken Met al., 2018, Omics-based responses induced by bosentan in human hepatoma HepaRG cell cultures, Archives of Toxicology, Vol: 92, Pages: 1939-1952, ISSN: 0340-5761

Bosentan is well known to induce cholestatic liver toxicity in humans. The present study was set up to characterize the hepatotoxic effects of this drug at the transcriptomic, proteomic, and metabolomic levels. For this purpose, human hepatoma-derived HepaRG cells were exposed to a number of concentrations of bosentan during different periods of time. Bosentan was found to functionally and transcriptionally suppress the bile salt export pump as well as to alter bile acid levels. Pathway analysis of both transcriptomics and proteomics data identified cholestasis as a major toxicological event. Transcriptomics results further showed several gene changes related to the activation of the nuclear farnesoid X receptor. Induction of oxidative stress and inflammation were also observed. Metabolomics analysis indicated changes in the abundance of specific endogenous metabolites related to mitochondrial impairment. The outcome of this study may assist in the further optimization of adverse outcome pathway constructs that mechanistically describe the processes involved in cholestatic liver injury.

Journal article

Ebbels TMD, Rodriguez-Martinez A, Dumas M-E, Keun HCet al., 2018, Advances in Computational Analysis of Metabolomic NMR Data, NMR-based Metabolomics

Book chapter

Athersuch TJ, Lau CH, Behrends V, Keun HCet al., 2018, CHAPTER 13: NMR Spectroscopy of Cell Culture, Tissues, and Other Biofluids, New Developments in NMR, Pages: 324-359

© The Royal Society of Chemistry 2018. NMR spectroscopy can provide a wealth of information on cellular metabolism and is frequently used in metabolomics application that use cultured cells, tissues, and whole organisms. Central to these analyses are the protocols for sample harvest, which incorporate procedures for quenching metabolic processes to preserve samples in a state that is representative of their source. In this chapter, the main considerations are discussed with reference to literature exemplars. In the latter half of the chapter, less commonly studied biofluids that also have specific sample preparation requirements are discussed, with a focus on cerebrospinal fluid, faeces, bile, seminal fluid, and milk.

Book chapter

Hilmenyuk T, Ruckstuhl CA, Hayoz M, Berchtold C, Nuoffer J-M, Solanki S, Keun HC, Beavis PA, Riether C, Ochsenbein AFet al., 2017, T cell inhibitory mechanisms in a model of aggressive Non-Hodgkin's Lymphoma, OncoImmunology, Vol: 7, ISSN: 2162-4011

A reduced immune surveillance due to immune deficiency or treatment with immunosuppressive drugs is associated with a higher risk to develop aggressive Non-Hodgkin's lymphoma (NHL). Nevertheless, NHL also develops in immunocompetent patients indicating an escape from the immune system. T cell function in advanced aggressive lymphoma is not well characterized and the molecular mechanisms how malignant B cells influence T cell function are ill-defined. We therefore studied T cell function in Eμ-myc transgenic mice that develop an aggressive B cell lymphoma with some similarities to human Burkitt-lymphoma (BL). In advanced lymphoma, the number of T cells was severely reduced and the remaining CD4+ and CD8+ T cells lost the capacity to produce effector cytokines and expand upon re-stimulation. T cells in lymphoma-bearing mice were characterized by the expression of the immune inhibitory molecules programmed death (PD)-1, 2B4 and lymphocyte activation protein (LAG)-3. The proto-oncogene c-Myc not only drives cell proliferation and disease progression but also induces apoptosis of the malignant cells. We found that apoptotic lymphoma cells release purine metabolites that inhibit T cell function. Taken together, our data document that the characteristic high cell turnover and apoptotic rate in aggressive NHL induce a severe T cell dysfunction mediated by several immune-inhibitory mechanisms including ligation of inhibitory ligands and purine metabolites. Blocking a single mechanism only partially restored T cell function and did not increase survival of lymphoma mice.

Journal article

Georgiadis P, Liampa I, Hebels DG, Krauskopf J, Chatziioannou A, Valavanis I, de Kok TMCM, Kleinjans JCS, Bergdahl IA, Melin B, Spaeth F, Palli D, Vermeulen RCH, Vlaanderen J, Chadeau-Hyam M, Vineis P, Kyrtopoulos SA, EnviroGenomarkers consortiumet al., 2017, Evolving DNA methylation and gene expression markers of B-cell chronic lymphocytic leukemia are present in pre-diagnostic blood samples more than 10 years prior to diagnosis., BMC Genomics, Vol: 18, ISSN: 1471-2164

BACKGROUND: B-cell chronic lymphocytic leukemia (CLL) is a common type of adult leukemia. It often follows an indolent course and is preceded by monoclonal B-cell lymphocytosis, an asymptomatic condition, however it is not known what causes subjects with this condition to progress to CLL. Hence the discovery of prediagnostic markers has the potential to improve the identification of subjects likely to develop CLL and may also provide insights into the pathogenesis of the disease of potential clinical relevance. RESULTS: We employed peripheral blood buffy coats of 347 apparently healthy subjects, of whom 28 were diagnosed with CLL 2.0-15.7 years after enrollment, to derive for the first time genome-wide DNA methylation, as well as gene and miRNA expression, profiles associated with the risk of future disease. After adjustment for white blood cell composition, we identified 722 differentially methylated CpG sites and 15 differentially expressed genes (Bonferroni-corrected p < 0.05) as well as 2 miRNAs (FDR < 0.05) which were associated with the risk of future CLL. The majority of these signals have also been observed in clinical CLL, suggesting the presence in prediagnostic blood of CLL-like cells. Future CLL cases who, at enrollment, had a relatively low B-cell fraction (<10%), and were therefore less likely to have been suffering from undiagnosed CLL or a precursor condition, showed profiles involving smaller numbers of the same differential signals with intensities, after adjusting for B-cell content, generally smaller than those observed in the full set of cases. A similar picture was obtained when the differential profiles of cases with time-to-diagnosis above the overall median period of 7.4 years were compared with those with shorted time-to-disease. Differentially methylated genes of major functional significance include numerous genes that encode for transcription factors, especially members of the homeobox family, while

Journal article

Kuepfer L, Clayton O, Thiel C, Cordes H, Nudischer R, Blank LM, Baier V, Heymans S, Caiment F, Roth A, Fluri DA, Kelm JM, Castell J, Selevsek N, Schlapbach R, Keun H, Hynes J, Sarkans U, Gmuender H, Herwig R, Niederer S, Schuchhardt J, Segall M, Kleinjans Jet al., 2017, A model-based assay design to reproduce in vivo patterns of acute drug-induced toxicity., Archives of Toxicology, Vol: 92, Pages: 553-555, ISSN: 0340-5761

For more than a decade pharmaceutical R&D has been hampered by considerable attrition rates during clinical trials. The main reasons for drug failure is related to the lack of efficacy, limitations with respect to ADME (absorption, distribution, metabolism and excretion) properties, and—in approximately 30% of the cases—unforeseen toxicity (Kola and Landis 2004). The majority of adverse drug reactions observed in the clinical phase refer to organ injuries, e.g. of the cardiovascular system, the liver, the central nervous system and skeletal muscle (Cook et al. 2014). This clearly demonstrates the limited predictive accuracy of current preclinical models such as the rodent bioassay in evaluating repeated dose toxicity for predicting human toxic risks. It has been argued that overall, only 43% of toxic effects in humans may be correctly predicted by applying rodent-based safety evaluation protocols due to the fact that these assays tend to generate relatively large numbers of false negative as well as false positive read outs (Hartung 2009).

Journal article

Maitre L, Lau C-HE, Vizcaino E, Robinson O, Casas M, Siskos AP, Want EJ, Athersuch T, Slama R, Vrijheid M, Keun HC, Coen Met al., 2017, Assessment of metabolic phenotypic variability in children's urine using H-1 NMR spectroscopy, Scientific Reports, Vol: 7, ISSN: 2045-2322

The application of metabolic phenotyping in clinical and epidemiological studies is limited by a poor understanding of inter-individual, intra-individual and temporal variability in metabolic phenotypes. Using 1H NMR spectroscopy we characterised short-term variability in urinary metabolites measured from 20 children aged 8–9 years old. Daily spot morning, night-time and pooled (50:50 morning and night-time) urine samples across six days (18 samples per child) were analysed, and 44 metabolites quantified. Intraclass correlation coefficients (ICC) and mixed effect models were applied to assess the reproducibility and biological variance of metabolic phenotypes. Excellent analytical reproducibility and precision was demonstrated for the 1H NMR spectroscopic platform (median CV 7.2%). Pooled samples captured the best inter-individual variability with an ICC of 0.40 (median). Trimethylamine, N-acetyl neuraminic acid, 3-hydroxyisobutyrate, 3-hydroxybutyrate/3-aminoisobutyrate, tyrosine, valine and 3-hydroxyisovalerate exhibited the highest stability with over 50% of variance specific to the child. The pooled sample was shown to capture the most inter-individual variance in the metabolic phenotype, which is of importance for molecular epidemiology study design. A substantial proportion of the variation in the urinary metabolome of children is specific to the individual, underlining the potential of such data to inform clinical and exposome studies conducted early in life.

Journal article

Chaudhari U, Ellis JK, Wagh V, Nemade H, Hescheler J, Keun HC, Sachinidis Aet al., 2017, Metabolite signatures of doxorubicin induced toxicity in human induced pluripotent stem cell-derived cardiomyocytes., Amino Acids, Vol: 49, Pages: 1955-1963, ISSN: 0939-4451

Drug-induced off-target cardiotoxicity, particularly following anti-cancer therapy, is a major concern in new drug discovery and development. To ensure patient safety and efficient pharmaceutical drug development, there is an urgent need to develop more predictive cell model systems and distinct toxicity signatures. In this study, we applied our previously proposed repeated exposure toxicity methodology and performed (1)H NMR spectroscopy-based extracellular metabolic profiling in culture medium of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) exposed to doxorubicin (DOX), an anti-cancer agent. Single exposure to DOX did not show alteration in the basal level of extracellular metabolites while repeated exposure to DOX caused reduction in the utilization of pyruvate and acetate, and accumulation of formate compared to control culture medium. During drug washout, only pyruvate showed reversible effect and restored its utilization by hiPSC-CMs. On the other hand, formate and acetate showed irreversible effect in response to DOX exposure. DOX repeated exposure increased release of lactate dehydrogenase (LDH) in culture medium suggesting cytotoxicity events, while declined ATP levels in hiPSC-CMs. Our data suggests DOX perturbed mitochondrial metabolism in hiPSC-CMs. Pyruvate, acetate and formate can be used as metabolite signatures of DOX induced cardiotoxicity. Moreover, the hiPSC-CMs model system coupled with metabolomics technology offers a novel and powerful approach to strengthen cardiac safety assessment during new drug discovery and development.

Journal article

Lau C-HE, Tredwell GD, Ellis JK, Lam EW-F, Keun HCet al., 2017, Metabolomic characterisation of the effects of oncogenic PIK3CA transformation in a breast epithelial cell line, SCIENTIFIC REPORTS, Vol: 7, ISSN: 2045-2322

Somatic mutations in PIK3CA are frequently found in a number of human cancers, including breast cancer, altering cellular physiology and tumour sensitivity to chemotherapy. This renders PIK3CA an attractive molecular target for early detection and personalised therapy. Using 1H Nuclear Magnetic Resonance spectroscopy (NMR) and Gas Chromatography – Mass Spectrometery (GC-MS) together with 13C stable isotope-labelled glucose and glutamine as metabolic tracers, we probed the phenotypic changes in metabolism following a single copy knock-in of mutant PIK3CA (H1047R) in the MCF10A cell line, an important cell model for studying oncogenic transformation in breast tissues. We observed effects in several metabolic pathways, including a decrease in glycerophosphocholine level together with increases in glutaminolysis, de novo fatty acid synthesis and pyruvate entry into the tricarboxylic acid cycle. Our findings highlight altered glyceroplipid metabolism and lipogenesis, as key metabolic phenotypes of mutant PIK3CA transformation that are recapitulated in the MCF10A cellular model.

Journal article

Itkonen HM, Brown M, Urbanucci A, Tredwell G, Lau CH, Barfeld S, Hart C, Guldvik IJ, Takhar M, Heemers HV, Erho N, Bloch K, Davicioni E, Derua R, Waelkens E, Mohler JL, Clarke N, Swinnen JV, Keun HC, Rekvig OP, Mills IGet al., 2017, Lipid degradation promotes prostate cancer cell survival, ONCOTARGET, Vol: 8, Pages: 38264-38275, ISSN: 1949-2553

Prostate cancer is the most common male cancer and androgen receptor (AR) is the major driver of the disease. Here we show that Enoyl-CoA delta isomerase 2 (ECI2) is a novel AR-target that promotes prostate cancer cell survival. Increased ECI2 expression predicts mortality in prostate cancer patients (p = 0.0086). ECI2 encodes for an enzyme involved in lipid metabolism, and we use multiple metabolite profiling platforms and RNA-seq to show that inhibition of ECI2 expression leads to decreased glucose utilization, accumulation of fatty acids and down-regulation of cell cycle related genes. In normal cells, decrease in fatty acid degradation is compensated by increased consumption of glucose, and here we demonstrate that prostate cancer cells are not able to respond to decreased fatty acid degradation. Instead, prostate cancer cells activate incomplete autophagy, which is followed by activation of the cell death response. Finally, we identified a clinically approved compound, perhexiline, which inhibits fatty acid degradation, and replicates the major findings for ECI2 knockdown. This work shows that prostate cancer cells require lipid degradation for survival and identifies a small molecule inhibitor with therapeutic potential.

Journal article

Valbuena GN, Tortarolo M, Bendotti C, Cantoni L, Keun HCet al., 2017, Altered metabolic profiles associate with toxicity in SOD1G93A astrocyte-neuron co-cultures, Scientific Reports, Vol: 7, ISSN: 2045-2322

Non-cell autonomous processes involving astrocytes have been shown to contribute to motor neuron degeneration in amyotrophic lateral sclerosis. Mutant superoxide dismutase 1 (SOD1G93A) expression in astrocytes is selectively toxic to motor neurons in co-culture, even when mutant protein is expressed only in astrocytes and not in neurons. To examine metabolic changes in astrocyte-spinal neuron co-cultures, we carried out metabolomic analysis by 1H NMR spectroscopy of media from astrocyte-spinal neuron co-cultures and astrocyte-only cultures. We observed increased glucose uptake with SOD1G93A expression in all co-cultures, but while co-cultures with only SOD1G93A neurons had lower extracellular lactate, those with only SOD1G93A astrocytes exhibited the reverse. Reduced branched-chain amino acid uptake and increased accumulation of 3-methyl-2-oxovalerate were observed in co-culture with only SOD1G93A neurons while glutamate was reduced in all co-cultures expressing SOD1G93A. The shifts in these coupled processes suggest a potential block in glutamate processing that may impact motor neuron survival. We also observed metabolic alterations which may relate to oxidative stress responses. Overall, the different metabolite changes observed with the two SOD1G93A cell types highlight the role of the astrocyte-motor neuron interaction in the resulting metabolic phenotype, requiring further examination of altered metabolic pathways and their impact on motor neuron survival.

Journal article

Sikka A, Barnes EME, Keun HC, 2017, The role of biophysics and engineering in investigating tumour pH and its regulation, Convergent Science Physical Oncology, Vol: 3, ISSN: 2057-1739

Solid tumours tend to have a high metabolic rate, inducing the intracellular accumulation of lactic acid and CO2 with a concomitant decrease in pH. Since many intracellular processes are pH-sensitive, tumour progression is therefore dependent on the maintenance of intracellular and extracellular pH within a narrow range. Cancer cells employ a number of functionally redundant regulatory mechanisms to maintain pH homeostasis. Several small molecule inhibitors which target these mechanisms are currently in clinical trials with promising outcomes. In order to investigate tumour pH regulation and to stratify and monitor patient response to these treatments, we need to be able to accurately measure pH in situ. Although pH measurement techniques are continually being developed, they are still limited for example by poor probe targeting and spatio-temporal resolution. In this review, we discuss the important role of biophysics and engineering in tackling the challenges faced when measuring tumour pH.

Journal article

Chatziioannou A, Georgiadis P, Hebels DG, Liampa I, Valavanis I, Bergdahl IA, Johansson A, Palli D, Chadeau-Hyam M, Siskos AP, Keun H, Botsivali M, de Kok TMCM, Perez AE, Kleinjans JCS, Vineis P, Kyrtopoulos SAet al., 2017, Blood-based omic profiling supports female susceptibility to tobacco smoke-induced cardiovascular diseases, SCIENTIFIC REPORTS, Vol: 7, ISSN: 2045-2322

We recently reported that differential gene expression and DNA methylation profiles in blood leukocytes of apparently healthy smokers predicts with remarkable efficiency diseases and conditions known to be causally associated with smoking, suggesting that blood-based omic profiling of human populations may be useful for linking environmental exposures to potential health effects. Here we report on the sex-specific effects of tobacco smoking on transcriptomic and epigenetic features derived from genome-wide profiling in white blood cells, identifying 26 expression probes and 92 CpG sites, almost all of which are affected only in female smokers. Strikingly, these features relate to numerous genes with a key role in the pathogenesis of cardiovascular disease, especially thrombin signaling, including the thrombin receptors on platelets F2R (coagulation factor II (thrombin) receptor; PAR1) and GP5 (glycoprotein 5), as well as HMOX1 (haem oxygenase 1) and BCL2L1 (BCL2-like 1) which are involved in protection against oxidative stress and apoptosis, respectively. These results are in concordance with epidemiological evidence of higher female susceptibility to tobacco-induced cardiovascular disease and underline the potential of blood-based omic profiling in hazard and risk assessment.

Journal article

Sood D, Johnson N, Jain P, Siskos AP, Bennett M, Gilham C, Busana MC, Peto J, dos-Santos-Silva I, Keun HC, Fletcher Oet al., 2017, CYP3A7*1C allele is associated with reduced levels of 2-hydroxylation pathway oestrogen metabolites, British Journal of Cancer, Vol: 116, Pages: 382-388, ISSN: 1532-1827

background: Endogenous sex hormones are well-established risk factors for breast cancer; the contribution of specific oestrogen metabolites (EMs) and/or ratios of specific EMs is less clear. We have previously identified a CYP3A7*1C allele that is associated with lower urinary oestrone (E1) levels in premenopausal women. The purpose of this analysis was to determine whether this allele was associated with specific pathway EMs.methods: We measured successfully 12 EMs in mid-follicular phase urine samples from 30 CYP3A7*1C carriers and 30 non-carriers using HPLC-MS/MS.results: In addition to having lower urinary E1 levels, CYP3A7*1C carriers had significantly lower levels of four of the 2-hydroxylation pathway EMs that we measured (2-hydroxyestrone, P=1.1 × 10−12; 2-hydroxyestradiol, P=2.7 × 10−7; 2-methoxyestrone, P=1.9 × 10−12; and 2-methoxyestradiol, P=0.0009). By contrast, 16α-hydroxylation pathway EMs were slightly higher in carriers and significantly so for 17-epiestriol (P=0.002).conclusions: The CYP3A7*1C allele is associated with a lower urinary E1 levels, a more pronounced reduction in 2-hydroxylation pathway EMs and a lower ratio of 2-hydroxylation:16α-hydroxylation EMs in premenopausal women. To further characterise the association between parent oestrogens, EMs and subsequent risk of breast cancer, characterisation of additional genetic variants that influence oestrogen metabolism and large prospective studies of a broad spectrum of EMs will be required.

Journal article

Siskos AP, Jain P, Romisch-Margl W, Bennet M, Achaintre D, Asad Y, Marney L, Richardson L, Koulman A, Griffin JL, Raynaud F, Scalbert A, Adamski J, Prehn C, Keun HCet al., 2016, Interlaboratory reproducibility of a targeted metabolomics platform for analysis of human serum and plasma, Analytical Chemistry, Vol: 89, Pages: 656-665, ISSN: 1086-4377

A critical question facing the field of metabolomics is whether data obtained from different centers can be effectively compared and combined. An important aspect of this is the interlaboratory precision (reproducibility) of the analytical protocols used. We analyzed human samples in six laboratories using different instrumentation but a common protocol (the AbsoluteIDQ p180 kit) for the measurement of 189 metabolites via liquid chromatography (LC) or flow injection analysis (FIA) coupled to tandem mass spectrometry (MS/MS). In spiked quality control (QC) samples 82% of metabolite measurements had an interlaboratory precision of <20%, while 83% of averaged individual laboratory measurements were accurate to within 20%. For 20 typical biological samples (serum and plasma from healthy individuals) the median interlaboratory coefficient of variation (CV) was 7.6%, with 85% of metabolites exhibiting a median interlaboratory CV of <20%. Precision was largely independent of the type of sample (serum or plasma) or the anticoagulant used but was reduced in a sample from a patient with dyslipidaemia. The median interlaboratory accuracy and precision of the assay for standard reference plasma (NIST SRM 1950) were 107% and 6.7%, respectively. Likely sources of irreproducibility were the near limit of detection (LOD) typical abundance of some metabolites and the degree of manual review and optimization of peak integration in the LC–MS/MS data after acquisition. Normalization to a reference material was crucial for the semi-quantitative FIA measurements. This is the first interlaboratory assessment of a widely used, targeted metabolomics assay illustrating the reproducibility of the protocol and how data generated on different instruments could be directly integrated in large-scale epidemiological studies.

Journal article

Perryman R, O'Neill K, Keun H, Syed Net al., 2016, DETERMINING THE ROLE OF NICOTINAMIDE METABOLISM IN CHEMOSENSITIVITY IN GLIOBLASTOMA MULTIFORME, 21st Annual Scientific Meeting and Education Day of the Society-for-Neuro-Oncology, Publisher: OXFORD UNIV PRESS INC, Pages: 36-36, ISSN: 1522-8517

Conference paper

Perng W, Oken E, Roumeliotaki T, Sood D, Siskos AP, Chalkiadaki G, Dermitzaki E, Vafeiadi M, Kyrtopoulos S, Kogevinas M, Keun HC, Chatzi Let al., 2016, Leptin, acylcarnitine metabolites and development of adiposity in the Rhea mother-child cohort in Crete, Greece., Obesity Science and Practice, Vol: 2, Pages: 471-476, ISSN: 2055-2238

OBJECTIVE: This study aims to investigate relations of serum leptin at age 4 with development of adiposity and linear growth during 3 years of follow-up among 75 Greek children and to identify serum metabolites associated with leptin at age 4 and to characterize their associations with adiposity gain and linear growth. METHODS: Linear regression models that accounted for maternal age, education and gestational weight gain and child's age and sex were used to examine associations of leptin and leptin-associated metabolites measured at age 4 with indicators of adiposity and linear growth at age 7. RESULTS: Each 1-unit increment in natural log-(ln)-transformed leptin corresponded with 0.33 (95% CI: 0.10, 0.55) units greater body mass index-for-age z-score gain during follow-up. Likewise, higher levels of the leptin-associated metabolites methylmalonyl-carnitine and glutaconyl-carnitine corresponded with 0.14 (95% CI: 0.01, 0.27) and 0.07 (95% CI: -0.01, 0.16) units higher body mass index-for-age z-score gain, respectively. These relationships did not differ by sex or baseline weight status and were independent of linear growth. CONCLUSIONS: These findings suggest that leptin, methylmalonyl-carnitine and possibly glutaconyl-carnitine are associated with weight gain during early childhood. Future studies are warranted to confirm these findings in other populations.

Journal article

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