Association between Vitamin A and E Forms and Prostate Cancer Risk in the Singapore Prostate Cancer Study.

PURPOSE: This study aimed to assess associations between forms of vitamin A and E (both individually and collectively) and the risk of prostate cancer, as well as identify potential effect modifiers. METHODS: Utilizing data from the Singapore Prostate Cancer Study, a hospital-based case-control study, we measured the serum concentrations of 15 different forms of vitamins A and E in 156 prostate cancer patients and 118 control subjects, using a high-performance liquid chromatography technique. These forms included retinol, lutein, zeaxanthin, α-cryptoxanthin, ß-cryptoxanthin, α-carotene, ß-carotene, lycopene, ubiquinone, δ-tocopherol, γ-tocopherol, α-tocopherol, δ-tocotrienol, γ-tocotrienol, and α-tocotrienol. The odds ratio and 95% confidence interval for associations between vitamin A and E and prostate cancer risk were estimated using logistic regression models after adjustment for potential confounders. The analyses were further stratified by smoking and alcohol consumption status. The mixture effect of micronutrient groups was evaluated using weighted quantile sum regression. RESULTS: Higher concentrations of retinol, lutein, α-carotene, ß-carotene, ubiquinone, α-tocopherol, δ-tocotrienol, γ-tocotrienol, and α-tocotrienol were significantly and positively associated with overall prostate cancer risk. Among ever-smokers, associations were stronger for lutein, ß-cryptoxanthin and ß-carotene compared with never-smokers. Among regular alcohol drinkers, associations were stronger for lutein, ß-cryptoxanthin, ubiquinone, γ-tocotrienol and α-tocotrienol compared with non-regular alcohol drinkers. Retinol and α-tocotrienol contributed most to the group indices 'vitamin A and provitamin A carotenoids' and 'vitamin E', respectively. CONCLUSIONS: Several serum vitamin A and E forms were associated with prostate cancer risk, with significant effect modification by smoking and alcohol consumption status. Our findings shed light on prostate cancer etiology.

Annexin-A1 deficiency attenuates stress-induced tumor growth via fatty acid metabolism in mice: an Integrated multiple omics analysis on the stress- microbiome-metabolite-epigenetic-oncology (SMMEO) axis.

Background: High emotional or psychophysical stress levels have been correlated with an increased risk and progression of various diseases. How stress impacts the gut microbiota to influence metabolism and subsequent cancer progression is unclear. Methods: Feces and serum samples from BALB/c ANXA1+/+ and ANXA1-/- mice with or without chronic restraint stress were used for 16S rRNA gene sequencing and GC-MS metabolomics analysis to investigate the effect of stress on microbiome and metabolomics during stress and breast tumorigenesis. Breast tumors samples from stressed and non-stressed mice were used to perform Whole-Genome Bisulfite Sequencing (WGBS) and RNAseq analysis to construct the potential network from candidate hub genes. Finally, machine learning and integrated analysis were used to map the axis from chronic restraint stress to breast cancer development. Results: We report that chronic stress promotes breast tumor growth via a stress-microbiome-metabolite-epigenetic-oncology (SMMEO) axis. Chronic restraint stress in mice alters the microbiome composition and fatty acids metabolism and induces an epigenetic signature in tumors xenografted after stress. Subsequent machine learning and systemic modeling analyses identified a significant correlation among microbiome composition, metabolites, and differentially methylated regions in stressed tumors. Moreover, silencing Annexin-A1 inhibits the changes in the gut microbiome and fatty acid metabolism after stress as well as basal and stress-induced tumor growth. Conclusions: These data support a physiological axis linking the microbiome and metabolites to cancer epigenetics and inflammation. The identification of this axis could propel the next phase of experimental discovery in further understanding the underlying molecular mechanism of tumorigenesis caused by physiological stress.

PFKP alleviates glucose starvation-induced metabolic stress in lung cancer cells via AMPK-ACC2 dependent fatty acid oxidation.

Cancer cells adopt metabolic reprogramming to promote cell survival under metabolic stress. A key regulator of cell metabolism is AMP-activated protein kinase (AMPK) which promotes catabolism while suppresses anabolism. However, the underlying mechanism of AMPK in handling metabolic stress in cancer remains to be fully understood. In this study, by performing a proteomics screening of AMPK-interacting proteins in non-small-cell lung cancer (NSCLC) cells, we discovered the platelet isoform of phosphofructokinase 1 (PFKP), a rate-limiting enzyme in glycolysis. Moreover, PFKP was found to be highly expressed in NSCLC patients associated with poor survival. We demonstrated that the interaction of PFKP and AMPK was greatly enhanced upon glucose starvation, a process regulated by PFKP-associated metabolites. Notably, the PFKP-AMPK interaction promoted mitochondrial recruitment of AMPK which subsequently phosphorylated acetyl-CoA carboxylase 2 (ACC2) to enhance long-chain fatty acid oxidation, a process helping maintenance of the energy and redox homeostasis and eventually promoting cancer cell survival under glucose starvation. Collectively, we revealed a critical non-glycolysis-related function of PFKP in regulating long-chain fatty acid oxidation via AMPK to alleviate glucose starvation-induced metabolic stress in NSCLC cells.

Untargeted Metabolomic Analysis of Nonvolatile and Volatile Glucosinolates in Brassicaceae.

Glucosinolates (GLSs) are a group of plant secondary metabolites mainly found in Cruciferous plants. The main hydrolysis products of GLSs, isothiocyanates (ITCs), are the bioactive metabolites that have shown plant defense and human cancer prevention properties. Untargeted metabolomic analysis of plant metabolites can uncover the profiles of these bioactive phytochemicals in specific plants and discover potential human health promoting products. We have developed an integrated metabolomic analysis method for plant samples, with specific focus on nonvolatile GLSs and volatile ITCs. In this chapter, we describe in detail the protocols, including metabolite extraction, high resolution LC-MS and GC-MS analysis, and data processing. The method is readily applicable to untargeted analysis of other nonvolatile and volatile metabolites in plants.

Transcriptomic analysis identifies dysregulated genes and functional networks in human small airway epithelial cells exposed to ambient PM2.5.

Cellular models exhibiting human physiological features of pseudostratified columnar epithelia, provide a more realistic approach for elucidating detailed mechanisms underlying PM2.5-induced pulmonary toxicity. In this study, we characterized the barrier and mucociliary functions of differentiated human small airway epithelial cells (SAECs), cultured at the air-liquid interface (ALI). Due to the presence of mucociliary protection, particle internalization was reduced, with a concomitant decrease in cytotoxicity in differentiated S-ALI cells, as compared to conventional submerged SAEC cultures. After 24-hour exposure to PM2.5 surrogates, 117 up-regulated genes and 156 down-regulated genes were detected in S-ALI cells, through transcriptomic analysis using the Affymetrix Clariom™ S Human Array. Transcription-level changes in >60 signaling pathways, were revealed by functional annotation of the 273 differentially expressed genes, using the PANTHER Gene List Analysis. These pathways are involved in multiple cellular processes, that include inflammation and apoptosis. Exposure to urban PM2.5 led to complex responses in airway epithelia, including a net induction of downstream pro-inflammatory and pro-apoptotic responses. Collectively, this study highlights the importance of using the more advanced ALI model rather than the undifferentiated submerged model, to avoid over-assessment of inhaled particle toxicity in human. The results of our study also suggest that reduction of ambient PM2.5 concentrations would have a protective effect on respiratory health in humans.

Urban PM2.5 reduces angiogenic ability of endothelial cells in an alveolar-capillary co-culture lung model.

Adverse health effects arising from exposure to fine particulates have become a major concern. Angiogenesis is a vital physiological process for the growth and development of cells and structures in the human body, whereby excessive or insufficient vessel growth could contribute to pathogenesis of diseases. We therefore evaluated indirect effects of carbon black (CB) and inhalable airborne particles on the angiogenic ability of unexposed Human Umbilical Vein Endothelial Cells (HUVECs) by co-culturing HUVECs with pre-exposed Small Airway Epithelial Cells (SAECs). As endothelial cells are major components of blood vessels and potential targets of fine particles, we investigated if lung epithelial cells exposed to ambient PM2.5 surrogates could induce bystander effects on neighboring unexposed endothelial cells in an alveolar-capillary co-culture lung model. Epithelial exposure to CB at a non-toxic dose of 25 µg/mL reduced endothelial tube formation and cell adhesion in co-cultured HUVECs, and decreased expression of angiogenic genes in SAECs. Similarly, exposure of differentiated SAECs to PM2.5 surrogates reduced cell reproductive ability, adhesion and tube formation of neighboring HUVECs. This indicates epithelial exposure to CB and urban PM2.5 surrogates both compromised the angiogenic ability of endothelial cells through bystander effects, thereby potentially perturbing the ventilation-perfusion ratio and affecting lung function.

An Integrated Metabolomics Study of Glucosinolate Metabolism in Different Brassicaceae Genera.

Glucosinolates are a group of plant secondary metabolites that can be hydrolyzed into a variety of breakdown products such as isothiocyanates, thiocyanates, and nitriles. These breakdown products can facilitate plant defense and function as attractants to natural enemies of insect pests. As part of the diet, some of these compounds have shown cancer-preventing activities, and the levels of these metabolites in the edible parts of the plants are of interest. In this study, we systematically examined variations in glucosinolates, their precursors, and their breakdown products in 12 commonly consumed vegetables of the Brassicaceae family with gas chromatography-quadrupole time-of-flight mass spectrometer (GC-Q-TOF/MS), liquid chromatography-quadrupole time-of-flight mass spectrometer (LC-Q-TOF/MS), and liquid chromatography-triple quadrupole mass spectrometer (LC-QQQ/MS), using both untargeted and targeted approaches. The findings were integrated with data from literature to provide a comprehensive map of pathways for biosynthesis of glucosinolates and isothiocyanates. The levels of precursor glucosinolates are found to correlate well with their downstream breakdown products. Further, the types and abundances of glucosinolates among different genera are significantly different, and these data allow the classification of plants based on morphological taxonomy. Further validation on three genera, which are grown underground, in damp soil, and above ground, suggests that each genus has its specific biosynthetic pathways and that there are variations in some common glucosinolate biosynthesis pathways. Our methods and results provide a good starting point for further investigations into specific aspects of glucosinolate metabolism in the Brassica vegetables.

Toxicity Study of Zinc Oxide Nanoparticles in Cell Culture and in Drosophila melanogaster.

Zinc oxide nanoparticles (ZnO NPs) have a wide range of applications, but the number of reports on ZnO NP-associated toxicity has grown rapidly in recent years. However, studies that elucidate the underlying mechanisms for ZnO NP-induced toxicity are scanty. We determined the toxicity profiles of ZnO NPs using both in vitro and in vivo experimental models. A significant decrease in cell viability was observed in ZnO NP-exposed MRC5 lung fibroblasts, showing that ZnO NPs exert cytotoxic effects. Similarly, interestingly, gut exposed to ZnO NPs exhibited a dramatic increase in reactive oxygen species levels (ROS) in the fruit fly Drosophila. More in-depth studies are required to establish a risk assessment for the increased usage of ZnO NPs by consumers.

Association between serum heavy metals and prostate cancer risk - A multiple metal analysis.

BACKGROUND: Prostate cancer is one of the most prevalent cancers in men. Exposure to heavy metals and their association with prostate cancer risk has been studied extensively, but combined effects remain largely inconclusive. OBJECTIVES: To elucidate the association between serum concentrations of heavy metals and prostate cancer risk. METHODS: Inductively coupled plasma mass spectrometry (ICP-MS) was used to determine the concentrations of a panel of 10 heavy metals (Mn, Cu, Zn, As, Se, Sb, Co, Cu, Cd and Pb) in serum samples of 141 cases and 114 controls in the Singapore Prostate Cancer Study. Linear probit regression models were used to estimate risk differences (RDs) and 95% confidence intervals (CIs) for the associations between log-centered serum metal concentrations and prostate cancer risk with adjustment for potential confounders. Bayesian kernel machine regression (BKMR) models were used to account for nonlinear, interactive, and joint metal effects. RESULTS: Using probit regression, four heavy metals (As, Zn, Mn, Sb) were significantly and positively associated with prostate cancer risk in the unadjusted models. Using BKMR analysis, both As and Zn had positive risk differences on prostate cancer risk when all other metals were held fixed at the 25th and 50th percentiles (RD, 25th percentile: As: 0.15, Zn: 0.19, RD, 50th percentile: As: 0.45, Zn: 0.37). In addition, the overall mixture risk difference was positive and the 95% credible intervals did not include 0 when all metals in the mixture were jointly above their 55th percentile, as compared to when all metals were below their median values. CONCLUSIONS: In summary, we found positive associations between the serum levels of As and Zn and prostate cancer risk on the risk difference scale using BKMR models. The overall mixture effect was also associated with increased prostate cancer risk. Future studies are warranted to validate these findings in prospective studies.

Targeted metabolomics reveals differential biological effects of nanoplastics and nanoZnO in human lung cells.

Engineered nanomaterials are of public health concern. Recently, there has been an increasing attention on the toxicity of nanoplastics and nanoZnO because of their increasing utilization and presence in the environment. However, knowledge of their toxicological behavior and metabolic interactions with the cellular machinery that determine their potential health effects are extremely limited. In this study, the cellular uptake, cytotoxic effects, and metabolic responses of bronchus epithelial (BEAS-2B) cells exposed to nanopolystyrene (nanoPS) and a widely used metallic nanoparticle, nanoZnO, were investigated using a tandem mass spectrometry-based metabolomics approach. The results revealed that even with low cytotoxicity, these nanoparticles (NPs) affected cell metabolism. NanoPS exposure showed autophagic- and endoplasmic reticulum (ER) stress-related metabolic changes such as increased in amino acids and tricarboxylic acid cycle (TCA) intermediate metabolites, a process known to play a critical role in regulating cell resistance to cytotoxic effects. Both metabolomics profiling and ER-stress pathway, together with quantitative real-time RT-polymerase chain reaction (qRT-PCR) analyses, demonstrated that autophagy was reciprocally regulated to couple metabolic and transcriptional reprograming. In contrast, nanoZnO-induced ROS-mediated cell death was associated with mitochondrial dysfunction and interference in regulating energy metabolism. Collectively, these two types of NPs were observed to cause perturbations albeit differential in cellular metabolism associated with their cytotoxic effects. Our findings provided an in depth understanding of metabolic changes influenced by two different types of NPs, with contrasting molecular mechanisms for the adverse effects observed.

Employing multi-omics to elucidate the hormetic response against oxidative stress exerted by nC60 on Daphnia pulex.

This study evaluated hormetic effect of oxidative stress exerted by fullerene crystals (nC60) on Daphnia pulex, employing transcriptomics and metabolomics. D. pulex were exposed to various concentrations of nC60 for 21 days. Hormetic effect of oxidative stress was most evident after 7 days, with markedly increased L-Glutathione (GSH) concentration and Superoxide Dismutase (SOD) activity at low doses of nC60 exposure, and oppositely at high doses. The transcriptomics and metabolomics were used to elucidate the molecular mechanism underlying the hormesis in oxidative stress. There were significant alterations in major pathways involving oxidative stress and energy metabolism in D. pulex. Some important intermediates and the expression of their regulatory genes coincided with each other with first up-regulated and then down-regulated with the concentration increased, consistent with the hormesis description. The nC60 interfered the TCA cycle of D. pulex. The synthesis of L-cysteine and glutamate was directly affected, and further disturbed the synthesis of GSH. This work is of great significance to provide the molecular-level evidence into the hormetic effect in oxidative stress of D. pulex exposed to nC60.

Impacts of peat-forest smoke on urban PM2.5 in the Maritime Continent during 2012-2015: Carbonaceous profiles and indicators.

This study characterizes impacts of peat-forest (PF) smoke on an urban environment through carbonaceous profiles of >260 daily PM2.5 samples collected during 2012, 2013 and 2015. Organic carbon (OC) and elemental carbon (EC) comprising eight carbonaceous fractions are examined for four sample groups - non-smoke-dominant (NSD), smoke-dominant (SD), episodic PM2.5 samples at the urban receptor, and near-source samples collected close to PF burning sites. PF smoke introduced much larger amounts of OC than EC, with OC accounting for up to 94% of total carbon (TC), or increasing by up to 20 times in receptor PM2.5. SD PM2.5 at the receptor site and near-source samples have OC3 and EC1 as the dominant fractions. Both sample classes also exhibit char-EC >1.4 times of soot-EC, characterizing smoldering-dominant PF smoke, unlike episodic PM2.5 at the receptor site featuring large amounts of pyrolyzed organic carbon (POC) and soot-EC. Relative to the mean NSD PM2.5 at the receptor, increasing strength of transboundary PF smoke enriches OC3 and OC4 fractions, on average, by factors of >3 for SD samples, and >14 for episodic samples. A peat-forest smoke (PFS) indicator, representing the concentration ratio of (OC2+OC3+POC) to soot-EC, shows a temporal trend satisfactorily correlating with an organic marker (levoglucosan) of biomass burning. The PFS indicator systematically differentiates influences of PF smoke from source to urban receptor sites, with a progressive mean of 3.6, 13.4 and 20.1 for NSD, SD and episodic samples respectively at the receptor site, and 54.7 for the near-source PM2.5. A PFS indicator of ≥5.0 is proposed to determine dominant influence of transboundary PF smoke on receptor urban PM2.5 in the equatorial Asia with ∼90% confidence. Assessing >2900 hourly OCEC data in 2017-2018 supports the applicability of the PFS indicator to evaluate hourly impacts of PF smoke on receptor urban PM2.5 in the Maritime Continent.

Occurrence and distribution of pesticides in precipitation as revealed by targeted screening through GC-MS/MS.

Facing the tough challenge of precise measurement of ever-increasing numbers of organic contaminants in the environment, there is an urgent need for more reliable and cost-effective methodologies. In this study, we developed and validated a screening method for analysis of over 450 pesticides in precipitation using gas chromatography with tandem mass spectrometry (GC-MS/MS) in multiple reaction monitoring (MRM) mode. Solid phase extraction (SPE) was applied to extract target analytes from precipitation. Using this targeted approach, we managed to detect 123 pesticides with maximum retention time shifts below 0.1 min (except for DEET) in 101 precipitation samples collected between October 2015 and March 2017 in Singapore. This is probably the first study to report the measurements of a wide range of pesticides in precipitation. A spectrum of insecticides, herbicides, fungicides and their synergists were detected and among them DEET, malathion and carbaryl were the most frequently detected pesticides (detection frequency: 100%, 96% & 67%). The Spearman correlations suggest that some pesticides of different subgroups had significant correlations. It is believed that these finding could shed light on the understanding of the contribution of precipitation to environmental contaminants in water cycle.

Detection of Lung Cancer: Concomitant Volatile Organic Compounds and Metabolomic Profiling of Six Cancer Cell Lines of Different Histological Origins.

In recent years, there has been an extensive search for a non-invasive screening technique for early detection of lung cancer. Volatile organic compound (VOC) analysis in exhaled breath is one such promising technique. This approach is based on the fact that tumor growth is accompanied by unique oncogenesis, leading to detectable changes in VOC emitting profile. Here, we conducted a comprehensive profiling of VOCs and metabolites from six different lung cancer cell lines and one normal lung cell line using mass spectrometry. The concomitant VOCs and metabolite profiling allowed significant discrimination between lung cancer and normal cell, nonsmall cell lung cancer (NSCLC) and small cell lung cancer (SCLC), as well as between different subtypes of NSCLC. It was found that a combination of benzaldehyde, 2-ethylhexanol, and 2,4-decadien-1-ol could serve as potential volatile biomarkers for lung cancer. A detailed correlation between nonvolatile metabolites and VOCs can demonstrate possible biochemical pathways for VOC production by the cancer cells, thus enabling further optimization of VOCs as biomarkers. These findings could eventually lead to noninvasive early detection of lung cancer and differential diagnosis of lung cancer subtypes, thus revolutionizing lung cancer treatment.

Comparison of hepatic and serum lipid signatures in hepatocellular carcinoma patients leads to the discovery of diagnostic and prognostic biomarkers.

We compared hepatic and serum lipid changes in hepatocellular carcinoma (HCC) patients to have a better understanding of the molecular pathogenesis of this disease and discovery novel lipid biomarkers. Hepatic and serum lipid profiling was conducted in paired liver and serum samples from 50 HCC patients and 24 healthy controls. A total of 20 hepatic and 40 serum lipid signatures were identified, yet there was hardly any significant correlation between them. The results indicated that triglycerides and phosphatidylcholines contributed significantly to altered hepatic lipids, whereas triglycerides and phosphatidylethanolamine-based plasmalogens (PEp) contributed most to altered serum lipids. In serum, PEp (36:4) and (40:6) showed a fair capability to discriminate HCC patients from healthy controls, and were significantly associated with HCC tumor grades (p < 0.05), and thus were identified as potential diagnostic and prognostic biomarkers of HCC. These findings were confirmed by a validation study conducted in an independent cohort consisting of 18 HCC, 20 cirrhosis patients, and 20 healthy controls. This study suggests that hepatic and serum lipid signatures of HCC have to be considered as mostly independent, and the results imply potential roles of PEp species, particularly PEp (36:4) and (40:6), as serum biomarkers for HCC diagnosis and progression.

Simultaneous Quantification of 22 Glucosinolates in 12 Brassicaceae Vegetables by Hydrophilic Interaction Chromatography-Tandem Mass Spectrometry.

Glucosinolates, which are unique to Brassicaceae vegetables, have diverse biological activities, including antimicrobial, antioxidant, and anticancer actions. In this study, we applied hydrophilic interaction chromatography-tandem mass spectrometry (HILIC-MS/MS) to the simultaneous quantification of 22 glucosinolates in 12 Brassicaceae vegetables, including pak choi, choy sum, Chinese cabbage, cauliflower, cabbage, broccoli, Kai Lan, Brussels sprouts, rocket salad, daikon radish, red cherry radish, and watercress. Significant differences in concentration and composition of glucosinolates were observed among these vegetables. Cabbage had the highest level of total glucosinolates (µg/g dry weight: 19 551.2 ± 1317.7), whereas Kai Lan had the lowest level (7611.3 ± 868.4). Aliphatic and indole glucosinolates were the major components in the 12 vegetables ranging from 76 to 100%, except watercress (37%). On the basis of the content of glucosinolates, the 12 vegetables were well distinguishable and classified according to their morphological taxonomy. This study presents a HILIC-MS/MS approach for quantification of glucosinolates, and demonstrates the potential of glucosinolate profiles for Brassicaceae species identification.

Omega-6-derived oxylipin changes in serum of patients with hepatitis B virus-related liver diseases.

INTRODUCTION: Chronic hepatitis B virus (HBV) infection is the main etiologic risk factor for hepatocellular carcinoma (HCC). Early studies indicated that the increase of omega-6-derived oxylipins may be involved in the pathogenesis of HBV-related HCC, yet their changes during the distinct clinical phases of chronic HBV infection remain unclear. To fill this gap, in this study we investigated the omega-6-derived oxylipin profiles in patients with three major clinical stages of chronic HBV infection (chronic hepatitis B, liver cirrhosis, and HCC). METHODS: Eighteen omega-6-derived oxylipins were quantified in serum samples of 34 patients with chronic hepatitis B, 46 patients with HBV-related liver cirrhosis, 38 patients with HBV-related HCC, and 50 healthy controls using liquid chromatography tandem mass spectrometry. RESULTS: Seven oxylipins were found to be altered in patients with HBV-related liver diseases, including 9,10-dihydroxyoctadecenoic acid (9,10-DiHOME), 12,13-DiHOME, 14,15-dihydroxyeicosatrienoic acid (14,15-DiHETrE), 13-hydroxyoctadecadienoic acid (13-HODE), 12-hydroxyeicosatetraenoic acid (12-HETE), 11-HETE, and thromboxane B2 (TXB2). Of these, three oxylipins derived from the cytochrome P450 (CYP450) pathways including 9,10-DiHOME, 12,13-DiHOME, and 14,15-DiHETrE were found to be associated with the levels of α-fetoprotein (AFP), a tumor marker. In combination with AFP, age, and gender, a combination of these seven differential oxylipins could significantly enhance the prediction of HBV-related liver diseases, particularly for liver cirrhosis (p < 0.05). CONCLUSION: This study for the first time shows the correlations between CYP450-derived oxylipins and the progression of chronic HBV infection, and sheds a new light on the surveillance of HBV-related live diseases using oxylipins.

Metabolic signatures of four major histological types of lung cancer cells.

INTRODUCTION: Histologically lung cancer is classified into four major types: adenocarcinoma (Ad), squamous cell carcinoma (SqCC), large cell carcinoma (LCC), and small cell lung cancer (SCLC). Presently, our understanding of cellular metabolism among them is still not clear. OBJECTIVES: The goal of this study was to assess the cellular metabolic profiles across these four types of lung cancer using an untargeted metabolomics approach. METHODS: Six lung cancer cell lines, viz., Ad (A549 and HCC827), SqCC (NCl-H226 and NCl-H520), LCC (NCl-H460), and SCLC (NCl-H526), were analyzed using liquid chromatography quadrupole time-of-flight mass spectrometry, with normal human small airway epithelial cells (SAEC) as the control group. The principal component analysis (PCA) was performed to identify the metabolic signatures that had characteristic alterations in each histological type. Further, a metabolite set enrichment analysis was performed for pathway analysis. RESULTS: Compared to the SAEC, 31, 27, 34, 34, 32, and 39 differential metabolites mainly in relation to nucleotides, amino acid, and fatty acid metabolism were identified in A549, HCC827, NCl-H226, NCl-H520, NCl-H460, and NCl-H526 cells, respectively. The metabolic signatures allowed the six cancerous cell lines to be clearly separated in a PCA score plot. CONCLUSION: The metabolic signatures are unique to each histological type, and appeared to be related to their cell-of-origin and mutation status. The changes are useful for assessing the metabolic characteristics of lung cancer, and offer potential for the establishment of novel diagnostic tools for different origin and oncogenic mutation of lung cancer.

Plasma fatty acids and risk of colon and rectal cancers in the Singapore Chinese Health Study.

Fatty acid composition in plasma captures both dietary intake and endogenous synthesis. Prospective analyses of plasma fatty acid composition are needed to establish the role of monounsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs) on risk of developing colorectal cancer. To evaluate associations between plasma fatty acid composition and colon or rectal cancer risk separately, a nested case-control study of 350 colorectal (211 colon and 139 rectal) cancer cases and an equal number of individually matched control subjects was conducted within the Singapore Chinese Health Study, a cohort of 63,257 men and women recruited between 1993 and 1998. Fatty acids in pre-diagnostic plasma were quantified using gas chromatography-tandem mass spectrometry. Conditional odds ratios (ORs) and 95% confidence intervals (CIs) comparing highest to lowest quartiles are presented. For colon cancer, inverse associations were reported with higher essential PUFAs, α-linolenic acid (OR = 0.41; 95% CI: 0.23, 0.73; Ptrend = 0.005) and linoleic acid (OR = 0.43; 95% CI: 0.23, 0.82; Ptrend = 0.008). Higher desaturase activity in the n-6 PUFA synthesis pathway estimated by the arachidonic:linoleic acid ratio was associated with increased colon cancer risk (OR = 3.53; 95% CI: 1.82, 6.85; Ptrend = 0.006), whereas higher desaturase activity in the MUFA synthesis pathway estimated by the oleic:stearic acid ratio was associated with decreased colon cancer risk (OR = 0.42; 95% CI: 0.19, 0.92; Ptrend = 0.024). There was no significant association between the essential fatty acids or the desaturase indices and rectal cancer risk. Endogenous synthesis of arachidonic and oleic acids has an impact on colon cancer development.

Metabolic signatures and risk of type 2 diabetes in a Chinese population: an untargeted metabolomics study using both LC-MS and GC-MS.

AIMS/HYPOTHESIS: Metabolomics has provided new insight into diabetes risk assessment. In this study we characterised the human serum metabolic profiles of participants in the Singapore Chinese Health Study cohort to identify metabolic signatures associated with an increased risk of type 2 diabetes. METHODS: In this nested case-control study, baseline serum metabolite profiles were measured using LC-MS and GC-MS during a 6-year follow-up of 197 individuals with type 2 diabetes but without a history of cardiovascular disease or cancer before diabetes diagnosis, and 197 healthy controls matched by age, sex and date of blood collection. RESULTS: A total of 51 differential metabolites were identified between cases and controls. Of these, 35 were significantly associated with diabetes risk in the multivariate analysis after false discovery rate adjustment, such as increased branched-chain amino acids (leucine, isoleucine and valine), non-esterified fatty acids (palmitic acid, stearic acid, oleic acid and linoleic acid) and lysophosphatidylinositol (LPI) species (16:1, 18:1, 18:2, 20:3, 20:4 and 22:6). A combination of six metabolites including proline, glycerol, aminomalonic acid, LPI (16:1), 3-carboxy-4-methyl-5-propyl-2-furanpropionic acid and urea showed the potential to predict type 2 diabetes in at-risk individuals with high baseline HbA1c levels (≥6.5% [47.5 mmol/mol]) with an AUC of 0.935. Combined lysophosphatidylglycerol (LPG) (12:0) and LPI (16:1) also showed the potential to predict type 2 diabetes in individuals with normal baseline HbA1c levels (<6.5% [47.5 mmol/mol]; AUC = 0.781). CONCLUSIONS/INTERPRETATION: Our findings show that branched-chain amino acids and NEFA are potent predictors of diabetes development in Chinese adults. Our results also indicate the potential of lysophospholipids for predicting diabetes.