Differential Inhibition of Anaplerotic Pyruvate Carboxylation and Glutaminolysis-Fueled Anabolism Underlies Distinct Toxicity of Selenium Agents in Human Lung Cancer

Past chemopreventive human trials on dietary selenium supplements produced controversial outcomes. They largely employed selenomethionine (SeM)-based diets. SeM was less toxic than selenite or methylseleninic acid (MSeA) to lung cancer cells. We thus investigated the toxic action of these Se agents in two non-small cell lung cancer (NSCLC) cell lines and ex vivo organotypic cultures (OTC) of NSCLC patient lung tissues. Stable isotope-resolved metabolomics (SIRM) using 13C6-glucose and 13C5,15N2-glutamine tracers with gene knockdowns were employed to examine metabolic dysregulations associated with cell type- and treatment-dependent phenotypic changes. Inhibition of key anaplerotic processes, pyruvate carboxylation (PyC) and glutaminolysis were elicited by exposure to MSeA and selenite but not by SeM. They were accompanied by distinct anabolic dysregulation and reflected cell type-dependent changes in proliferation/death/cell cycle arrest. NSCLC OTC showed similar responses of PyC and/or glutaminolysis to the three agents, which correlated with tissue damages. Altogether, we found differential perturbations in anaplerosis-fueled anabolic pathways to underlie the distinct anti-cancer actions of the three Se agents, which could also explain the failure of SeM-based chemoprevention trials.

Abstract 1836: Triple negative breast cancer: Metabolomics and flux analysis to identify targets for drug development

To date, no targeted therapies are clinically available to treat triple negative breast cancer (TNBC). This highly aggressive form of breast cancer (BCa) derives its name from the absence of estrogen receptor (ER+), progesterone receptor (PR+), and HER2/neu receptor (HER2+). These receptors are expressed in other subtypes of BCa (i.e. Luminal, HER2-enriched) and have been successfully targeted with therapeutics such as Tamoxifen and Herceptin. New therapeutics are needed to improve the prognosis for patients with TNBC. Metabolomics and metabolic flux analysis (MFA) were conducted to reveal differences in TNBC cell lines compared with hormone receptor-positive cell lines (ER+ and +/-HER2+) prior to and following treatment with chemotherapy drugs. Two triple-negative (MDA-MB-231 and MDA-MB-468) and two hormone-responsive (BT474 and MCF-7) cell lines were compared before and after treatment with Taxol®/Paclitaxel. The metabolic profiles were assessed using 1H NMR broad spectrum metabolomics, MFA using [U-13C]-glucose and [U-13C]-glutamine enriched media, and cytokine profiling of the media. Broad spectrum metabolomics analysis demonstrated differences in the metabolic profiles between the TNBC and hormone-responsive cell lines in the absence of treatment, with a higher level of amino acids (e.g. alanine, glutamate, glutamine, glutathione), short chain fatty acids (isobutyrate, β-hydroxybutyrate), and nucleotides and nucleotide sugars (ADP, ATP, UDP-glucose, UDP-glucuronate) in the TNBC cell lines. Further, MFA demonstrated that glucose utilization was greater in the TNBC cells (MDA-MB-468) compared to the hormone-responsive cells (MCF-7). In addition, 13C-labeled glycine and 13C-labeled glutathione were only observed in TNBC cell lines treated in the presence of [U-13C]-glucose. In response to Taxol treatment, more metabolites were altered in the hormone-responsive cell lines compared with the TNBC cells. Profiling of 80 inflammatory cytokines (RayBiotech arrays) also demonstrated different responses in secreted inflammatory signals following treatment. We observed significant upregulation in interleukins-4 and -16 in MDA-MB-468 cells, while there was a downregulation of osteoprotegerin in all four cell lines after treatment with Taxol. This approach holds promise for identifying biomarkers which may be leveraged for development of targeted treatments.

Citation Format: Delisha A. Stewart, Jason Winnike, Susan McRitchie, Wimal Pathmasiri, Susan Sumner. Triple negative breast cancer: Metabolomics and flux analysis to identify targets for drug development. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1836. doi:10.1158/1538-7445.AM2015-1836

Metabolomic profiling of a modified alcohol liquid diet model for liver injury in the mouse uncovers new markers of disease

Metabolomic evaluation of urine and liver was conducted to assess the biochemical changes that occur as a result of alcohol-induced liver injury. Male C57BL/6J mice were fed an isocaloric control- or alcohol-containing liquid diet with 35% of calories from corn oil, 18% protein and 47% carbohydrate/alcohol for up to 36 days ad libitum. Alcohol treatment was initiated at 7 g/kg/day and gradually reached a final dose of 21 g/kg/day. Urine samples were collected at 22, 30 and 36 days and, in additional treatment groups, liver and serum samples were harvested at 28 days. Steatohepatitis was induced in the alcohol-fed group since a 5-fold increase in serum alanine aminotransferase activity, a 6-fold increase in liver injury score (necrosis, inflammation and steatosis) and an increase in lipid peroxidation in liver were observed. Liver and urine samples were analyzed by nuclear magnetic resonance spectroscopy and electrospray infusion/Fourier transform ion cyclotron resonance-mass spectrometry. In livers of alcohol-treated mice the following changes were noted. Hypoxia and glycolysis were activated as evidenced by elevated levels of alanine and lactate. Tyrosine, which is required for l-DOPA and dopamine as well as thyroid hormones, was elevated possibly reflecting alterations of basal metabolism by alcohol. A 4-fold increase in the prostacyclin inhibitor 7,10,13,16-docosatetraenoic acid, a molecule important for regulation of platelet formation and blood clotting, may explain why chronic drinking causes serious bleeding problems. Metabolomic analysis of the urine revealed that alcohol treatment leads to decreased excretion of taurine, a metabolite of glutathione, and an increase in lactate, n-acetylglutamine and n-acetylglycine. Changes in the latter two metabolites suggest an inhibition of the kidney enzyme aminoacylase I and may be useful as markers for alcohol consumption.

Outbreak of vancomycin-resistant enterococci in a burn unit

OBJECTIVE

To investigate and control an outbreak of colonization and infection caused by vancomycin-resistant enterococci (VRE) in a burn intensive care unit (BICU).

DESIGN

Epidemiological investigation, including multiple point-prevalence culture surveys of patients and environment, cultures from hands of healthcare workers (HCWs), pulsed-field gel electrophoresis (PFGE) typing of patient and environmental isolates, case-control study, and institution and monitoring of control measures.

SETTING

BICU in an 800-bed university medical center in Galveston, Texas.

RESULTS

Between June 6, 1996, and July 14, 1997, 21 patients were colonized by VRE, and 4 of these patients developed bacteremia. Of 2,844 environmental cultures, 338 (11.9%) were positive, but all hand cultures from HCWs were negative. PFGE typing indicated that the outbreak was clonal, with VRE isolates from patients differing by < or =4 bands from the index case. Thirteen of 14 environmental isolates varied by < or =4 bands from the pattern of the index case. A case-control study analyzed by exact logistic regression identified diarrhea (odds ratio [OR], 43.9; 95% confidence interval [CI95], 5.5-infinity; P=.0001) and administration of an antacid (OR, 24.2; CI95, 2.9-infinity; P=.002) as independent risk factors for acquisition of VRE. During a 5-week period in October and November 1996, all patient and 317 environmental cultures were negative for VRE. The outbreak recurred from a contaminated electrocardiogram lead that had not been identified during the prior 5 weeks. VRE were finally eradicated from the BICU in July 1997, using barrier isolation and a very aggressive environmental decontamination program.

CONCLUSIONS

A VRE outbreak in a BICU over 13 months was caused by a single clone. After apparent eradication of VRE from a BICU, recrudescence of the outbreak occurred, evidently from a small inapparent source of environmental contamination. Changes in gastrointestinal (GI) tract function (motility) and administration of medications, other than antibiotics, that have an effect on the GI tract may increase the risk of GI tract colonization by VRE in burn patients. Application of barrier isolation and an aggressive environmental decontamination program can eradicate VRE from a burn population.