bims-mascan Biomed News
on Mass spectrometry in cancer research
Issue of 2019‒08‒18
sixteen papers selected by
Giovanny Rodriguez Blanco
The Beatson Institute for Cancer Research


  1. Mol Metab. 2019 Jul 30. pii: S2212-8778(19)30431-4. [Epub ahead of print]
    Pietzke M, Meiser J, Vazquez A.
      BACKGROUND: Formate is a one-carbon molecule at the crossroad between cellular and whole body metabolism, between host and microbiome metabolism, and between nutrition and toxicology. This centrality confers formate with a key role in human physiology and disease that is currently unappreciated.SCOPE OF REVIEW: Here we review the scientific literature on formate metabolism, highlighting cellular pathways, whole body metabolism, and interactions with the diet and the gut microbiome. We will discuss the relevance of formate metabolism in the context of embryonic development, cancer, obesity, immunometabolism, and neurodegeneration.
    MAJOR CONCLUSIONS: We will conclude with an outlook of some open questions bringing formate metabolism into the spotlight.
    Keywords:  Cancer; Formate metabolism; Immune system; Neurodegeneration; Obesity; One-carbon-metabolism
    DOI:  https://doi.org/10.1016/j.molmet.2019.05.012
  2. Mol Cell. 2019 Jul 23. pii: S1097-2765(19)30496-4. [Epub ahead of print]
    Yu W, Wang Z, Zhang K, Chi Z, Xu T, Jiang D, Chen S, Li W, Yang X, Zhang X, Wu Y, Wang D.
      Activated macrophages adapt their metabolic pathways to drive the pro-inflammatory phenotype, but little is known about the biochemical underpinnings of this process. Here, we find that lipopolysaccharide (LPS) activates the pentose phosphate pathway, the serine synthesis pathway, and one-carbon metabolism, the synergism of which drives epigenetic reprogramming for interleukin-1β (IL-1β) expression. Glucose-derived ribose and one-carbon units fed by both glucose and serine metabolism are synergistically integrated into the methionine cycle through de novo ATP synthesis and fuel the generation of S-adenosylmethionine (SAM) during LPS-induced inflammation. Impairment of these metabolic pathways that feed SAM generation lead to anti-inflammatory outcomes, implicating SAM as an essential metabolite for inflammatory macrophages. Mechanistically, SAM generation maintains a relatively high SAM:S-adenosylhomocysteine ratio to support histone H3 lysine 36 trimethylation for IL-1β production. We therefore identify a synergistic effect of glucose and amino acid metabolism on orchestrating SAM availability that is intimately linked to the chromatin state for inflammation.
    Keywords:  H3K36me3; S-adenosylmethionine; amino-acid metabolism; epigenetic reprogramming; glycolysis offshoots; inflammation; one-carbon metabolism
    DOI:  https://doi.org/10.1016/j.molcel.2019.06.039
  3. Blood. 2019 Aug 15. pii: blood.2019001034. [Epub ahead of print]
    Tabe Y, Lorenzi PL, Konopleva M.
      Tumor cells rewire metabolic pathways to adapt to their increased nutritional demands for energy, reducing equivalents, and cellular biosynthesis. Alternations in amino acid metabolism are one modality for satisfying those demands. Amino acids are not only components of proteins but also intermediate metabolites fueling multiple biosynthetic pathways. Amino acid-depletion therapies use heterologous enzymes or recombinant or engineered human enzymes to decrease the concentration of amino acids upon which tumor cells have become dependent for survival. Notably, such therapies have minimal effect on normal cells due to their ability to synthesize the targeted amino acids under conditions of nutrient stress. Here we review novel aspects of amino acid metabolism in hematologic malignancies and deprivation strategies using heterologous or engineered enzymes, focusing on four key amino acids: arginine, asparagine, glutamine, and cysteine. We also present the roles of amino acid metabolism in the immunosuppressive tumor microenvironment and in drug resistance, and we present an argument for the reclassification of amino acid-depleting enzymes as targeted therapies.
    DOI:  https://doi.org/10.1182/blood.2019001034
  4. Metabolites. 2019 Aug 09. pii: E164. [Epub ahead of print]9(8):
    Sakaguchi CA, Nieman DC, Signini EF, Abreu RM, Catai AM.
      This systematic review provides a qualitative appraisal of 24 high-quality metabolomics-based studies published over the past decade exploring exercise-induced alterations of the human metabolome. Of these papers, 63% focused on acute metabolite changes following intense and prolonged exercise. The best studies utilized liquid chromatography mass spectrometry (LC-MS/MS) analytical platforms with large chemical standard libraries and strong, multivariate bioinformatics support. These studies reported large-fold changes in diverse lipid-related metabolites, with more than 100 increasing two-fold or greater within a few hours post-exercise. Metabolite shifts, even after strenuous exercise, typically return to near pre-exercise levels after one day of recovery. Few studies investigated metabolite changes following acute exercise bouts of shorter durations (< 60 min) and workload volumes. Plasma metabolite shifts in these types of studies are modest in comparison. More cross-sectional and exercise training studies are needed to improve scientific understanding of the human system's response to varying, chronic exercise workloads. The findings derived from this review provide direction for future investigations focused on the body's metabolome response to exercise.
    Keywords:  exercise; metabolism; metabolomics; sports
    DOI:  https://doi.org/10.3390/metabo9080164
  5. Anal Chim Acta. 2019 Nov 08. pii: S0003-2670(19)30691-9. [Epub ahead of print]1080 22-34
    El Amrani M, Donners AAM, Hack CE, Huitema ADR, van Maarseveen EM.
      The promising pipeline of therapeutic monoclonal antibodies (mAbs) demands robust bioanalytical methods with swift development times for pharmacokinetic studies. Over the past decades ligand binding assays were the methods of choice for absolute quantification. However, the production of the required anti-idiotypic antibodies and ligands limits high-throughput method development for sensitive, accurate, and reproducible quantification of therapeutic mAbs. In recent years, high-resolution liquid chromatography tandem mass-spectrometry (LC-MS) systems have enabled absolute quantification of therapeutic mAbs with short method development times. These systems have additional benefits, such as a large linear dynamic range, a high specificity and the option of multiplexing. Here, we briefly discuss the current strategies for the quantification of therapeutic mAbs in biological matrices using LC-MS analysis based on top-down and middle-down quantitative proteomics. Then, we present the widely used bottom-up method in a six-step workflow, which can be used as guidance for quantitative LC-MS/MS method development of mAbs. Finally, strengths and weaknesses of the bottom-up method, which currently provides the most benefits, are discussed in detail.
    Keywords:  LC-MS/MS; Method development; Quantitative proteomics; Sample purification; Therapeutic monoclonal antibodies; Trypsin digestion
    DOI:  https://doi.org/10.1016/j.aca.2019.05.076
  6. Biochem J. 2019 Aug 15. pii: BCJ20190500. [Epub ahead of print]
    Dewulf JP, Gerin I, Rider MH, Veiga-da-Cunha M, Van Schaftingen E, Bommer GT.
      Most fatty acids (FAs) are straight chains and are synthesized by fatty acid synthase (FASN) using acetyl-CoA and malonyl-CoA units. Yet, FASN is known to be promiscuous as it may use methylmalonyl-CoA instead of malonylCoA and thereby introduce methyl-branches. We have recently found that the cytosolic enzyme ECHDC1 degrades ethylmalonyl-CoA and methylmalonyl-CoA, which presumably result from promiscuous reactions catalyzed by acetyl-CoA carboxylase on butyryl- and propionyl-CoA. Here, we tested the hypothesis that ECHDC1 is a metabolite repair enzyme that serves to prevent the formation of methyl- or ethyl-branched FAs by FASN.Using purified enzyme, we found that FASN can incorporate not only methylmalonyl-CoA but also ethylmalonylCoA, producing methyl- or ethyl-branched FAs. Using a combination of gas-chromatography and liquid chromatography coupled to mass spectrometry, we observed that inactivation of ECHDC1 in adipocytes led to an increase in several methyl-branched FAs (present in different lipid classes), while its overexpression reduced them below wild type levels. In contrast, formation of ethyl-branched FAs was observed almost exclusively in ECHDC1 knockout cells, indicating that ECHDC1 and the low activity of FASN towards ethylmalonyl-CoA efficiently prevent their formation. We conclude that ECHDC1 performs a typical metabolite repair function by destroying methyl- and ethylmalonyl-CoA. This reduces the formation of methyl-branched FAs and prevents the formation of ethyl-branched FAs by FASN. The identification of ECHDC1 as a key modulator of the abundance of methyl-branched FAs opens the way to investigate their function.
    Keywords:  Branched-chain-fatty-acids; ECHDC1; Ethylmalonyl-CoA; Fatty acid synthase; Metabolite-repair; Methylmalonyl-CoA
    DOI:  https://doi.org/10.1042/BCJ20190500
  7. Expert Rev Mol Diagn. 2019 Aug 15.
    Cheung PK, Ma MH, Tse HF, Yeung KF, Tsang HF, Chu MKM, Kan CM, Cho WCS, Ng LBW, Chan LWC, Wong SCC.
      Introduction: Metabolomics, the study of metabolites, is a promising research field for cancers. The metabolic pathway in a tumor cell is different from a normal tissue cell. There are two approaches to study the metabolism, targeted and untargeted. The general approach is that metabolomic data are interpreted by bioinformatics tools correlating with metabolomic databases to obtain significant findings. With the use of specific analysis tools, such as nuclear magnetic resonance (NMR) and mass spectrometer (MS) combined with chromatography, metabolic profile or metabolic fingerprint of various biological specimens could be obtained. The applications of metabolomics are used to discover potential cancer biomarkers and monitor the metastatic state, therapeutic and drug response for better patient management. Areas covered: In this review, the author introduce metabolomics and discuss the use of metabolomics approaches in different cancers, including the study of colorectal cancer, prostate cancer, liver cancer, pancreatic cancer and breast cancer using NMR and MS. Expert opinion: Knowledge on the molecular basis of cancer metabolism and its potential clinical applications has been improving recently. However, there are still many challenges for the technological development and integration of metabolomics with other omics spaces such as genomics. In the near future, it is expected that metabolomics will play an important role in cancer molecular diagnostics.
    Keywords:  MS; Metabolomics; NMR; cancer; metabolite profiling; molecular diagnostics; pharmacometabolomics; precision medicine
    DOI:  https://doi.org/10.1080/14737159.2019.1656530
  8. Genes Dev. 2019 Aug 15.
    Venkateswaran N, Lafita-Navarro MC, Hao YH, Kilgore JA, Perez-Castro L, Braverman J, Borenstein-Auerbach N, Kim M, Lesner NP, Mishra P, Brabletz T, Shay JW, DeBerardinis RJ, Williams NS, Yilmaz OH, Conacci-Sorrell M.
      Tumors display increased uptake and processing of nutrients to fulfill the demands of rapidly proliferating cancer cells. Seminal studies have shown that the proto-oncogene MYC promotes metabolic reprogramming by altering glutamine uptake and metabolism in cancer cells. How MYC regulates the metabolism of other amino acids in cancer is not fully understood. Using high-performance liquid chromatography (HPLC)-tandem mass spectrometry (LC-MS/MS), we found that MYC increased intracellular levels of tryptophan and tryptophan metabolites in the kynurenine pathway. MYC induced the expression of the tryptophan transporters SLC7A5 and SLC1A5 and the enzyme arylformamidase (AFMID), involved in the conversion of tryptophan into kynurenine. SLC7A5, SLC1A5, and AFMID were elevated in colon cancer cells and tissues, and kynurenine was significantly greater in tumor samples than in the respective adjacent normal tissue from patients with colon cancer. Compared with normal human colonic epithelial cells, colon cancer cells were more sensitive to the depletion of tryptophan. Blocking enzymes in the kynurenine pathway caused preferential death of established colon cancer cells and transformed colonic organoids. We found that only kynurenine and no other tryptophan metabolite promotes the nuclear translocation of the transcription factor aryl hydrocarbon receptor (AHR). Blocking the interaction between AHR and kynurenine with CH223191 reduced the proliferation of colon cancer cells. Therefore, we propose that limiting cellular kynurenine or its downstream targets could present a new strategy to reduce the proliferation of MYC-dependent cancer cells.
    Keywords:  AFMID; AHR; MYC; SLC1A5; SLC7A5; cancer; kynurenine; organoid; tryptophan metabolism
    DOI:  https://doi.org/10.1101/gad.327056.119
  9. Mass Spectrom Rev. 2019 Aug 12.
    Gomes FP, Yates JR.
      Progress in proteomics research has led to a demand for powerful analytical tools with high separation efficiency and sensitivity for confident identification and quantification of proteins, posttranslational modifications, and protein complexes expressed in cells and tissues. This demand has significantly increased interest in capillary electrophoresis-mass spectrometry (CE-MS) in the past few years. This review provides highlights of recent advances in CE-MS for proteomics research, including a short introduction to top-down mass spectrometry and native mass spectrometry (native MS), as well as a detailed overview of CE methods. Both the potential and limitations of these methods for the analysis of proteins and peptides in synthetic and biological samples and the challenges of CE methods are discussed, along with perspectives about the future direction of CE-MS. @ 2019 Wiley Periodicals, Inc. Mass Spec Rev 00:1-16, 2019.
    Keywords:  capillary electrophoresis-mass spectrometry; electrospray ionization; native mass spectrometry; proteomics; top-down mass spectrometry
    DOI:  https://doi.org/10.1002/mas.21599
  10. Anal Chem. 2019 Aug 13.
    Teav T, Gallart-Ayala H, van der Velpen V, Mehl F, Henry H, Ivanisevic J.
      Acylcarnitines and amino acids are key players in energy metabolism, however, analytical methods for comprehensive and straightforward quantitative profiling of these metabolites, without derivatization or use of ion-pairing agents, are lacking. We therefore developed a hydrophilic interaction chromatography (HILIC)-based high-resolution mass spectrometry (HRMS) method for the simultaneous quantification of acylcarnitines and amino acids in a single run, while taking advantage of HRMS data acquired in full scan mode to screen for additional derivatives and other polar metabolites. A single-step metabolite extraction with internal standard mixture (in methanol) warranted high-throughput sample preparation whose applicability was demonstrated on a panel of human biofluids (i.e. blood plasma, CSF and urine) and brain tissue. Method accuracy was within 90-106 % of validated NIST reference plasma concentrations for the panel of measured amino acids. Amino acid and acylcarnitine extraction recoveries were 87-100 % on average, depending on the concentration range spiked. The coefficient of variation was 1-10% and 1-25% for intra- and inter-day measurements, respectively, with the highest values for the metabolites at the limit of quantification, depending on the biofluid. Acylcarnitine and amino acid signatures or chemical composition barcodes of the different biofluids and human brain tissue were acquired and biofluid- and tissue-associated differences were discussed in the context of their respective physiological roles. Significant differences were observed in the amino acid profiles whereas acylcarnitine composition did not show biofluid-characteristic or brain region-specific pattern. The retrospective exploration of full scan all-ion-fragmentation data allowed us to extract the information on unsaturated and hydroxylated acylcarnitine species, amines, and purine and pyrimidine metabolites. This merged targeted and untargeted approach provides an innovative strategy for simultaneous and comprehensive assessment of acylcarnitine and amino acid metabolism in clinical research studies using relevant biofluids and tissue extracts.
    DOI:  https://doi.org/10.1021/acs.analchem.9b02373
  11. IUBMB Life. 2019 Aug 16.
    Baranovičová E, Galanda T, Galanda M, Hatok J, Kolarovszki B, Richterová R, Račay P.
      The brain tumours represent a complex tissue that has its own characteristic metabolic features and is interfaced with the whole organism. We investigated changes in basal blood plasma metabolites in the presence of primary brain tumour, their correlation with tumour grade, as well as the feasibility of statistical discrimination based on plasma metabolites. Together 60 plasma samples from patients with clinically defined glioblastoma, meningioma, oligodendrioglioma, astrocytoma, and non-specific glial tumour and plasma samples from 28 healthy volunteers without any cancer history were measured by NMR spectroscopy. In blood plasma of primary brain tumour patients, we found significantly increased levels of glycolytic metabolites glucose and pyruvate, and significantly decreased level of glutamine and also metabolites participating in tricarboxylic acid (TCA) cycle, citrate and succinate, when compared with controls. Further, plasma metabolites levels: tyrosine, phenylalanine, glucose, creatine and creatinine correlated significantly with tumour grade. In general, observed changes are parallel to the biochemistry expected for tumourous tissue and metabolic changes in plasma seem to follow the similar rules in all primary brain tumours, with very subtle variations among tumour types. Only two plasma metabolites tyrosine and phenylalanine were increased exclusively in blood plasma of patients with glioblastoma. Based on metabolite levels, an excellent discrimination between plasma from patient's tumours and controls was attainable. The metabolites creatine, pyruvate, glucose, formate, creatinine and citrate were of the highest discriminatory power.
    Keywords:  NMR spectroscopy; brain tumour; cancer; metabolomics; plasma
    DOI:  https://doi.org/10.1002/iub.2149
  12. Anal Bioanal Chem. 2019 Aug 14.
    Wu Q, Xu Y, Ji H, Wang Y, Zhang Z, Lu H.
      It is a challenge to expand the metabolome coverage of liquid chromatography (LC)-electrospray ionization (ESI) mass spectrometry (MS) based untargeted metabolomics analysis. The limited coverage is attributed to the weak signal of hydroxyl and carboxyl groups in ESI-MS and the limited capacity of LC separation for metabolites with a wide range of polarities. Here a new sample preparation procedure is proposed to solve these problems. Mixed-mode (reversed-phase and anion-exchange) solid-phase extraction sorbents were used to separate metabolites into hydrophilic amine, hydrophobic amine/alcohol, and organic acid groups. Then, alcohols and carboxylic acids in separated groups were tagged with pyridine with use of two derivatization systems for signal enhancement. Finally, hydrophilic amines were analyzed by LC-MS with a hydrophilic interaction LC column, and the two hydrophobic compound groups were analyzed by LC-MS with a C18 column. From the results for standard samples, the detection limits of the new method are lower than those of the classic solvent extraction-protein precipitation method by 3.3-70 times for five amino acids and by 65-1141 times for five fatty acids. Moreover, the detection limit of this new method is 125 ng mL-1 for cholesterol, which has no signal with the classic method even at 10 μg mL-1. In seminal plasma samples, 110 more metabolites were identified by this new method than by the traditional solvent extraction-protein precipitation method in positive-mode ESI (new method vs traditional method, 65 vs 22 identified by comparing MS/MS spectra with those of standards, 203 vs 136 identified by searching MS spectra in a published database). Among them, 53 carboxylic acids and 21 alcohols were identified only by the new method, and more hydrophilic amine metabolites, such as amino acids and nucleosides, were identified by the new method than by the classic method. Finally, in application to the study of male infertility, more potential biomarkers of oligoasthenoteratospermic infertility were found with the new method (46 potential biomarkers) than with the classic method (19 potential biomarkers) and previously reported methods (10-30 potential biomarkers). Thus, it is demonstrated that this new sample preparation method expands the detection coverage of LC-MS-based untargeted metabolomics methods and has application potential in biological research.
    Keywords:  Detection coverage; Infertility study; Liquid chromatography–mass spectrometry; Mixed-mode solid-phase extraction; Untargeted metabolomics
    DOI:  https://doi.org/10.1007/s00216-019-02010-x
  13. Rapid Commun Mass Spectrom. 2019 Aug 14.
    Nagai K, Uranbileg B, Chen Z, Fujioka A, Yamazaki T, Matsmoto Y, Tsukamoto H, Ikeda H, Yatomi Y, Chiba H, Hui SP, Nakazawa T, Saito R, Koshiba S, Aoki J, Saigusa D, Tomioka Y.
      RATIONALE: Hepatocellular carcinoma (HCC) is a highly malignant disease for which the development of prospective or prognostic biomarkers is urgently required. Although metabolomics is widely used for biomarker discovery, there are some bottlenecks regarding the comprehensiveness of detected features, reproducibility of methods, and identification of metabolites. In addition, the information on localization of metabolites in the tumor tissue is needed for functional analysis. Here, we developed a wide-polarity global metabolomics (G-Met) method, identified HCC biomarkers in human liver samples by high-definition mass spectrometry (HDMS) and demonstrated localization in cryosections using desorption electrospray ionization (DESI)-MS imaging (MSI) analysis.METHODS: Metabolic profiling of tumor (n=38) and nontumor (n=72) regions in human livers of HCC was performed by an ultra-high-performance liquid chromatography quadruple time of flight MS (UHPLC-QTOF/MS) equipped with a mixed-mode column. The HCC biomarker candidates were extracted by multivariate analyses and identified by matching values of the collision cross section and their fragment ions on the mass spectra obtained by HDMS. Cryosections of HCC livers, which included both tumor and nontumor regions, were analyzed by DESI-MSI.
    RESULTS: From the multivariate analysis, m/z 904.83 and m/z 874.79 were significantly high and low, respectively, in tumor samples and were identified as triglyceride (TG) 16:0/18:1(9Z)/20:1(11Z) and TG 16:0/18:1(9Z)/18:2(9Z,12Z) using the synthetic compounds. The TGs were clearly localized in the tumor or nontumor areas of the cryosection.
    CONCLUSIONS: Novel biomarkers for HCC were identified by a comprehensive and reproducible G-Met method with HDMS using a mixed-mode column. The combination analysis of UHPLC-QTOF/MS and DESI-MSI revealed that the different molecular species of TGs were associated with tumor distribution and were useful for characterizing the progression of tumor cells and discovering prospective biomarkers.
    DOI:  https://doi.org/10.1002/rcm.8551
  14. Sci Rep. 2019 Aug 12. 9(1): 11623
    van der Spek A, Broer L, Draisma HHM, Pool R, Albrecht E, Beekman M, Mangino M, Raag M, Nyholt DR, Dharuri HK, Codd V, Amin N, de Geus EJC, Deelen J, Demirkan A, Yet I, Fischer K, Haller T, Henders AK, Isaacs A, Medland SE, Montgomery GW, Mooijaart SP, Strauch K, Suchiman HED, Vaarhorst AAM, van Heemst D, Wang-Sattler R, Whitfield JB, Willemsen G, Wright MJ, Martin NG, Samani NJ, Metspalu A, Eline Slagboom P, Spector TD, Boomsma DI, van Duijn CM, Gieger C.
      Telomere shortening has been associated with multiple age-related diseases such as cardiovascular disease, diabetes, and dementia. However, the biological mechanisms responsible for these associations remain largely unknown. In order to gain insight into the metabolic processes driving the association of leukocyte telomere length (LTL) with age-related diseases, we investigated the association between LTL and serum metabolite levels in 7,853 individuals from seven independent cohorts. LTL was determined by quantitative polymerase chain reaction and the levels of 131 serum metabolites were measured with mass spectrometry in biological samples from the same blood draw. With partial correlation analysis, we identified six metabolites that were significantly associated with LTL after adjustment for multiple testing: lysophosphatidylcholine acyl C17:0 (lysoPC a C17:0, p-value = 7.1 × 10-6), methionine (p-value = 9.2 × 10-5), tyrosine (p-value = 2.1 × 10-4), phosphatidylcholine diacyl C32:1 (PC aa C32:1, p-value = 2.4 × 10-4), hydroxypropionylcarnitine (C3-OH, p-value = 2.6 × 10-4), and phosphatidylcholine acyl-alkyl C38:4 (PC ae C38:4, p-value = 9.0 × 10-4). Pathway analysis showed that the three phosphatidylcholines and methionine are involved in homocysteine metabolism and we found supporting evidence for an association of lipid metabolism with LTL. In conclusion, we found longer LTL associated with higher levels of lysoPC a C17:0 and PC ae C38:4, and with lower levels of methionine, tyrosine, PC aa C32:1, and C3-OH. These metabolites have been implicated in inflammation, oxidative stress, homocysteine metabolism, and in cardiovascular disease and diabetes, two major drivers of morbidity and mortality.
    DOI:  https://doi.org/10.1038/s41598-019-47282-6
  15. Anal Chim Acta. 2019 Nov 08. pii: S0003-2670(19)30789-5. [Epub ahead of print]1080 127-137
    Sun X, Heinrich P, Berger RS, Oefner PJ, Dettmer K.
      Glutathione is an essential intra- and extracellular antioxidant. The level of glutathione in the body is highly related to different disease states and is a useful indicator of disease risk and oxidative stress status. We have developed a sensitive, selective, and comprehensive LC-MS/MS method for the absolute quantification and 13C-tracer analysis of total glutathione using dithiothreitol for the reduction of glutathione disulfide. The limit of detection (LOD) was 0.01 μM, while the lower limit of quantification (LLOQ) was 0.78 μM, with the linear (R = 0.9997) range extending up to 100 μM. The intra-run and inter-run coefficients of variation of 2.49% and 2.04%, respectively, attest to high repeatability. Mean (±SD) recoveries of three different concentrations (low, medium, high) of GSH spiked into aliquots of HCT116 cells prior to cell extraction were 108.9% (±2.1), 100.8% (±8.3), and 99.9% (±7.1), respectively. Finally, using a 20 Da wide Q1 window in MRM mode, we were able to detect and relatively quantify all isotopic labeling states of GSH extracted from HCT116 cells fed with either 13C-labeled glucose or glutamine.
    Keywords:  Dithiothreitol; Glutathione isotope labeling pattern; HPLC; Reduction; Tandem mass spectrometry; Total glutathione quantification
    DOI:  https://doi.org/10.1016/j.aca.2019.07.001
  16. Anal Chem. 2019 Aug 14.
    Nguyen SN, Kyle JE, Dautel S, Sontag R, Luders T, Corley R, Ansong C, Carson J, Laskin J.
      Lipids are a naturally occurring group of molecules that not only contribute to the structural integrity of the lung preventing alveolar collapse but also play important roles in the anti-inflammatory responses and antiviral protection. Alteration in the type and spatial localization of lipids in the lung plays a crucial role in various diseases such as respiratory distress syndrome (RDS) in preterm infants and oxidative stress-influenced diseases such as pneumonia, emphysema and lung cancer following exposure to environmental stressors. The ability to accurately measure spatial distributions of lipids and metabolites in lung tissues provides important molecular insights related to lung function, development, and disease states. Nanospray desorption electrospray ionization (nano-DESI) and other ambient ionization mass spectrometry techniques enable label-free imaging of complex samples in their native state with minimal to absolutely no sample preparation. However, lipid coverage obtained in nano-DESI mass spectrometry imaging (MSI) experiments has not been previously characterized. In this work, the depth of lipid coverage in nano-DESI MSI of mouse lung tissues was compared to liquid chromatography tandem mass spectrometry (LC-MS/MS) lipidomics analysis of tissue extracts prepared using two different procedures: standard Folch extraction method of the whole lung samples and extraction into a 90% methanol/10% water mixture used in nano-DESI MSI experiments. A combination of positive and negative ionization mode nano-DESI MSI identified 265 unique lipids across 20 lipids subclasses and 19 metabolites (284 in total) in mouse lung tissues. Except for triacylglycerols (TG) species, nano-DESI MSI provided comparable coverage to LC-MS/MS experiments performed using methanol/water tissue extracts and up to 50% coverage in comparison with the Folch extraction-based whole lung lipidomics analysis. These results demonstrate the utility of nano-DESI MSI for comprehensive spatially resolved analysis of lipids in tissue sections. A combination of nano-DESI MSI and LC-MS/MS lipidomics is particularly useful for exploring changes in lipid distributions during lung development, as well as resulting from disease or exposure to environmental toxicants.
    DOI:  https://doi.org/10.1021/acs.analchem.9b02045