Publications by authors named "Daina Avizonis"

31 Publications

Glucose metabolism and pyruvate carboxylase enhance glutathione synthesis and restrict oxidative stress in pancreatic islets.

Cell Rep 2021 Nov;37(8):110037

Department of Cancer Biology, Dana-Farber Cancer Institute, 450 Brookline Ave., Boston, MA 02115, USA; Department of Medical Oncology, Dana-Farber Cancer Institute, Boston 02115, MA, USA; Department of Medicine, Harvard Medical School, 240 Longwood Ave., Boston, MA 02115, USA. Electronic address:

Glucose metabolism modulates the islet β cell responses to diabetogenic stress, including inflammation. Here, we probed the metabolic mechanisms that underlie the protective effect of glucose in inflammation by interrogating the metabolite profiles of primary islets from human donors and identified de novo glutathione synthesis as a prominent glucose-driven pro-survival pathway. We find that pyruvate carboxylase is required for glutathione synthesis in islets and promotes their antioxidant capacity to counter inflammation and nitrosative stress. Loss- and gain-of-function studies indicate that pyruvate carboxylase is necessary and sufficient to mediate the metabolic input from glucose into glutathione synthesis and the oxidative stress response. Altered redox metabolism and cellular capacity to replenish glutathione pools are relevant in multiple pathologies beyond obesity and diabetes. Our findings reveal a direct interplay between glucose metabolism and glutathione biosynthesis via pyruvate carboxylase. This metabolic axis may also have implications in other settings where sustaining glutathione is essential.
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http://dx.doi.org/10.1016/j.celrep.2021.110037DOI Listing
November 2021

Autophagy-dependent glutaminolysis drives superior IL21 production in HIV-1-specific CD4 T cells.

Autophagy 2021 Oct 6:1-18. Epub 2021 Oct 6.

Institut National de la Recherche Scientifique (INRS)-Centre Armand-Frappier Santé Biotechnologie, Laval, Quebec, Canada.

The maintenance of a strong IL21 production in memory CD4 T cells, especially in HIV-1-specific cells, represents a major correlate of natural immune protection against the virus. However, the molecular mechanisms underlying IL21 production during HIV-1 infection, which is only elevated among the naturally protected elite controllers (EC), are still unknown. We recently found out that lipophagy is a critical immune mediator that control an antiviral metabolic state following CD8A T cell receptor engagement, playing an important role in the natural control of HIV-1 infection. This led us to investigate whether the beneficial role of a strong macroautophagy/autophagy, could also be used to ensure effective IL21 production as well. Herein, we confirm that after both polyclonal and HIV-1-specific activation, memory CD4 T cells (Mem) from EC display enhanced activity of the autophagy-mediated proteolysis compared to ART. Our results indicate that the enhanced autophagy activity in EC was controlled by the energy-sensing PRKAA1 (protein kinase AMP-activated catalytic subunit alpha 1). We further confirmed the critical role of the autophagy-mediated proteolysis in the strong IL21 production in EC by using gene silencing as well as protease, PRKAA1, and lysosomal inhibitors. Finally, we established that high autophagy-mediated proteolysis in EC fuels their cellular rates of mitochondrial respiration due to glutaminolysis. Our data confirm the critical role of autophagy in dictating the metabolic input, which is required not only to ensure protective cytotoxic CD8A T cell responses, but also to provide strong IL21 production among antiviral CD4 T cells. AKG: alpha-ketoglutarate; ART: patients under antiretroviral therapy; ATG7: autophagy related 7; BaF: bafilomycin A; BECN1: beclin 1; Chloro.: chloroquine; EC: elite controllers; EIF4EBP1: eukaryotic translation initiation factor 4E binding protein 1; FOXO3: forkhead box O3; GLS: glutaminase; GLUD1: glutamate dehydrogenase 1; HIV: HIV-1-uninfected control donors; IFNG/IFN-γ: interferon gamma; IL21: interleukin 21; MTOR: mechanistic target of rapamycin kinase; PBMC: peripheral blood mononuclear cells; PRKAA1: protein kinase AMP-activated catalytic subunit alpha 1; SQSTM1: sequestosome 1; TCA: tricarboxylic acid cycle; ULK1: unc-51 like autophagy activating kinase.
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http://dx.doi.org/10.1080/15548627.2021.1972403DOI Listing
October 2021

STAT1 potentiates oxidative stress revealing a targetable vulnerability that increases phenformin efficacy in breast cancer.

Nat Commun 2021 06 3;12(1):3299. Epub 2021 Jun 3.

Department of Biochemistry, Microbiology and Immunology, Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, ON, Canada.

Bioenergetic perturbations driving neoplastic growth increase the production of reactive oxygen species (ROS), requiring a compensatory increase in ROS scavengers to limit oxidative stress. Intervention strategies that simultaneously induce energetic and oxidative stress therefore have therapeutic potential. Phenformin is a mitochondrial complex I inhibitor that induces bioenergetic stress. We now demonstrate that inflammatory mediators, including IFNγ and polyIC, potentiate the cytotoxicity of phenformin by inducing a parallel increase in oxidative stress through STAT1-dependent mechanisms. Indeed, STAT1 signaling downregulates NQO1, a key ROS scavenger, in many breast cancer models. Moreover, genetic ablation or pharmacological inhibition of NQO1 using β-lapachone (an NQO1 bioactivatable drug) increases oxidative stress to selectively sensitize breast cancer models, including patient derived xenografts of HER2+ and triple negative disease, to the tumoricidal effects of phenformin. We provide evidence that therapies targeting ROS scavengers increase the anti-neoplastic efficacy of mitochondrial complex I inhibitors in breast cancer.
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http://dx.doi.org/10.1038/s41467-021-23396-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8175605PMC
June 2021

Reprogramming of Nucleotide Metabolism Mediates Synergy between Epigenetic Therapy and MAP Kinase Inhibition.

Mol Cancer Ther 2021 01 21;20(1):64-75. Epub 2020 Oct 21.

Departments of Oncology and Experimental Medicine, McGill University, Lady Davis Institute and Segal Cancer Centre, Jewish General Hospital, Montreal, Quebec, Canada.

Small cell carcinoma of the ovary, hypercalcemic type (SCCOHT) is a rare but often lethal cancer that is diagnosed at a median age of 24 years. Optimal management of patients is not well defined, and current treatment remains challenging, necessitating the discovery of novel therapeutic approaches. The identification of SMARCA4-inactivating mutations invariably characterizing this type of cancer provided insights facilitating diagnostic and therapeutic measures against this disease. We show here that the BET inhibitor OTX015 acts in synergy with the MEK inhibitor cobimetinib to repress the proliferation of SCCOHT Notably, this synergy is also observed in some SMARCA4-expressing ovarian adenocarcinoma models intrinsically resistant to BETi. Mass spectrometry, coupled with knockdown of newly found targets such as thymidylate synthase, revealed that the repression of a panel of proteins involved in nucleotide synthesis underlies this synergy both and , resulting in reduced pools of nucleotide metabolites and subsequent cell-cycle arrest. Overall, our data indicate that dual treatment with BETi and MEKi represents a rational combination therapy against SCCOHT and potentially additional ovarian cancer subtypes.
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http://dx.doi.org/10.1158/1535-7163.MCT-20-0259DOI Listing
January 2021

Bisphosphoglycerate Mutase Deficiency Protects against Cerebral Malaria and Severe Malaria-Induced Anemia.

Cell Rep 2020 09;32(12):108170

Department of Human Genetics, McGill University, Montreal, QC H3A 0C7, Canada; McGill University Research Centre on Complex Traits, McGill University, Montreal, QC H3G 0B1, Canada; Department of Biochemistry, McGill University, Montreal, QC H3A 1A3, Canada. Electronic address:

The replication cycle and pathogenesis of the Plasmodium malarial parasite involves rapid expansion in red blood cells (RBCs), and variants of certain RBC-specific proteins protect against malaria in humans. In RBCs, bisphosphoglycerate mutase (BPGM) acts as a key allosteric regulator of hemoglobin/oxyhemoglobin. We demonstrate here that a loss-of-function mutation in the murine Bpgm (Bpgm) gene confers protection against both Plasmodium-induced cerebral malaria and blood-stage malaria. The malaria protection seen in Bpgm mutant mice is associated with reduced blood parasitemia levels, milder clinical symptoms, and increased survival. The protective effect of Bpgm involves a dual mechanism that enhances the host's stress erythroid response to Plasmodium-driven RBC loss and simultaneously alters the intracellular milieu of the RBCs, including increased oxyhemoglobin and reduced energy metabolism, reducing Plasmodium maturation, and replication. Overall, our study highlights the importance of BPGM as a regulator of hemoglobin/oxyhemoglobin in malaria pathogenesis and suggests a new potential malaria therapeutic target.
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http://dx.doi.org/10.1016/j.celrep.2020.108170DOI Listing
September 2020

Genome-Wide Screens Reveal that Resveratrol Induces Replicative Stress in Human Cells.

Mol Cell 2020 09 4;79(5):846-856.e8. Epub 2020 Aug 4.

Institute for Research in Immunology and Cancer, Université de Montréal, PO Box 6128, Downtown Station, Montréal, QC H3C 3J7, Canada. Electronic address:

Resveratrol is a natural product associated with wide-ranging effects in animal and cellular models, including lifespan extension. To identify the genetic target of resveratrol in human cells, we conducted genome-wide CRISPR-Cas9 screens to pinpoint genes that confer sensitivity or resistance to resveratrol. An extensive network of DNA damage response and replicative stress genes exhibited genetic interactions with resveratrol and its analog pterostilbene. These genetic profiles showed similarity to the response to hydroxyurea, an inhibitor of ribonucleotide reductase that causes replicative stress. Resveratrol, pterostilbene, and hydroxyurea caused similar depletion of nucleotide pools, inhibition of replication fork progression, and induction of replicative stress. The ability of resveratrol to inhibit cell proliferation and S phase transit was independent of the histone deacetylase sirtuin 1, which has been implicated in lifespan extension by resveratrol. These results establish that a primary impact of resveratrol on human cell proliferation is the induction of low-level replicative stress.
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http://dx.doi.org/10.1016/j.molcel.2020.07.010DOI Listing
September 2020

Glucose-dependent partitioning of arginine to the urea cycle protects β-cells from inflammation.

Nat Metab 2020 05 11;2(5):432-446. Epub 2020 May 11.

Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, USA.

Chronic inflammation is linked to diverse disease processes, but the intrinsic mechanisms that determine cellular sensitivity to inflammation are incompletely understood. Here, we show the contribution of glucose metabolism to inflammation-induced changes in the survival of pancreatic islet β-cells. Using metabolomic, biochemical and functional analyses, we investigate the protective versus non-protective effects of glucose in the presence of pro-inflammatory cytokines. When protective, glucose metabolism augments anaplerotic input into the TCA cycle via pyruvate carboxylase (PC) activity, leading to increased aspartate levels. This metabolic mechanism supports the argininosuccinate shunt, which fuels ureagenesis from arginine and conversely diminishes arginine utilization for production of nitric oxide (NO), a chief mediator of inflammatory cytotoxicity. Activation of the PC-urea cycle axis is sufficient to suppress NO synthesis and shield cells from death in the context of inflammation and other stress paradigms. Overall, these studies uncover a previously unappreciated link between glucose metabolism and arginine-utilizing pathways via PC-directed ureagenesis as a protective mechanism.
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http://dx.doi.org/10.1038/s42255-020-0199-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7568475PMC
May 2020

Repression of LKB1 by Sensitizes -Dependent Lymphoma to Biguanide Treatment.

Cell Rep Med 2020 May 19;1(2):100014. Epub 2020 May 19.

Goodman Cancer Research Centre, McGill University, Montreal, QC H3A 1A3, Canada.

Cancer cells display metabolic plasticity to survive stresses in the tumor microenvironment. Cellular adaptation to energetic stress is coordinated in part by signaling through the liver kinase B1 (LKB1)-AMP-activated protein kinase (AMPK) pathway. Here, we demonstrate that miRNA-mediated silencing of LKB1 confers sensitivity of lymphoma cells to mitochondrial inhibition by biguanides. Using both classic (phenformin) and newly developed (IM156) biguanides, we demonstrate that elevated expression in lymphoma cells promotes increased apoptosis to biguanide treatment and . This effect is driven by the -dependent silencing of LKB1, which reduces AMPK activation in response to complex I inhibition. Mechanistically, biguanide treatment induces metabolic stress in lymphoma cells by inhibiting TCA cycle metabolism and mitochondrial respiration, exposing metabolic vulnerability. Finally, we demonstrate a direct correlation between expression and biguanide sensitivity in human cancer cells. Our results identify expression as a potential biomarker for biguanide sensitivity in malignancies.
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http://dx.doi.org/10.1016/j.xcrm.2020.100014DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7249503PMC
May 2020

Methotrexate elicits pro-respiratory and anti-growth effects by promoting AMPK signaling.

Sci Rep 2020 05 12;10(1):7838. Epub 2020 May 12.

Department of Biochemistry, McGill University, Montréal, QC, H3G 1Y6, Canada.

One-carbon metabolism fuels the high demand of cancer cells for nucleotides and other building blocks needed for increased proliferation. Although inhibitors of this pathway are widely used to treat many cancers, their global impact on anabolic and catabolic processes remains unclear. Using a combination of real-time bioenergetics assays and metabolomics approaches, we investigated the global effects of methotrexate on cellular metabolism. We show that methotrexate treatment increases the intracellular concentration of the metabolite AICAR, resulting in AMPK activation. Methotrexate-induced AMPK activation leads to decreased one-carbon metabolism gene expression and cellular proliferation as well as increased global bioenergetic capacity. The anti-proliferative and pro-respiratory effects of methotrexate are AMPK-dependent, as cells with reduced AMPK activity are less affected by methotrexate treatment. Conversely, the combination of methotrexate with the AMPK activator, phenformin, potentiates its anti-proliferative activity in cancer cells. These data highlight a reciprocal effect of methotrexate on anabolic and catabolic processes and implicate AMPK activation as a metabolic determinant of methotrexate response.
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http://dx.doi.org/10.1038/s41598-020-64460-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7217946PMC
May 2020

eIF4A supports an oncogenic translation program in pancreatic ductal adenocarcinoma.

Nat Commun 2019 11 13;10(1):5151. Epub 2019 Nov 13.

Institute for Cancer Genetics, Department of Genetics and Development, Columbia University Medical Center, New York, NY, 10032, USA.

Pancreatic ductal adenocarcinoma (PDA) is a lethal malignancy with limited treatment options. Although metabolic reprogramming is a hallmark of many cancers, including PDA, previous attempts to target metabolic changes therapeutically have been stymied by drug toxicity and tumour cell plasticity. Here, we show that PDA cells engage an eIF4F-dependent translation program that supports redox and central carbon metabolism. Inhibition of the eIF4F subunit, eIF4A, using the synthetic rocaglate CR-1-31-B (CR-31) reduced the viability of PDA organoids relative to their normal counterparts. In vivo, CR-31 suppresses tumour growth and extends survival of genetically-engineered murine models of PDA. Surprisingly, inhibition of eIF4A also induces glutamine reductive carboxylation. As a consequence, combined targeting of eIF4A and glutaminase activity more effectively inhibits PDA cell growth both in vitro and in vivo. Overall, our work demonstrates the importance of eIF4A in translational control of pancreatic tumour metabolism and as a therapeutic target against PDA.
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http://dx.doi.org/10.1038/s41467-019-13086-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6853918PMC
November 2019

Translational and HIF-1α-Dependent Metabolic Reprogramming Underpin Metabolic Plasticity and Responses to Kinase Inhibitors and Biguanides.

Cell Metab 2018 12 20;28(6):817-832.e8. Epub 2018 Sep 20.

Lady Davis Institute, SMBD JGH, McGill University, Montreal, QC H3A 1A3, Canada; Gerald Bronfman Department of Oncology, McGill University, Montreal, QC H3A 1A3, Canada; Department of Biochemistry, McGill University, Montreal, QC H3A 1A3, Canada; Department of Experimental Medicine, McGill University, Montreal, QC H3A 1A3, Canada. Electronic address:

There is increasing interest in therapeutically exploiting metabolic differences between normal and cancer cells. We show that kinase inhibitors (KIs) and biguanides synergistically and selectively target a variety of cancer cells. Synthesis of non-essential amino acids (NEAAs) aspartate, asparagine, and serine, as well as glutamine metabolism, are major determinants of the efficacy of KI/biguanide combinations. The mTORC1/4E-BP axis regulates aspartate, asparagine, and serine synthesis by modulating mRNA translation, while ablation of 4E-BP1/2 substantially decreases sensitivity of breast cancer and melanoma cells to KI/biguanide combinations. Efficacy of the KI/biguanide combinations is also determined by HIF-1α-dependent perturbations in glutamine metabolism, which were observed in VHL-deficient renal cancer cells. This suggests that cancer cells display metabolic plasticity by engaging non-redundant adaptive mechanisms, which allows them to survive therapeutic insults that target cancer metabolism.
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http://dx.doi.org/10.1016/j.cmet.2018.09.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7252493PMC
December 2018

Interplay between ShcA Signaling and PGC-1α Triggers Targetable Metabolic Vulnerabilities in Breast Cancer.

Cancer Res 2018 09 21;78(17):4826-4838. Epub 2018 Jun 21.

Lady Davis Institute for Medical Research, Montreal, Quebec, Canada.

The ShcA adaptor protein transduces oncogenic signals downstream of receptor tyrosine kinases. We show here that breast tumors engage the ShcA pathway to increase their metabolism. ShcA signaling enhanced glucose catabolism through glycolysis and oxidative phosphorylation, rendering breast cancer cells critically dependent on glucose. ShcA signaling simultaneously increased the metabolic rate and flexibility of breast cancer cells by inducing the PGC-1α transcriptional coactivator, a central regulator of mitochondrial metabolism. Breast tumors that engaged ShcA signaling were critically dependent on PGC-1α to support their increased metabolic rate. PGC-1α deletion drastically delayed breast tumor onset in an orthotopic mouse model, highlighting a key role for PGC-1α in tumor initiation. Conversely, reduced ShcA signaling impaired both the metabolic rate and flexibility of breast cancer cells, rendering them reliant on mitochondrial oxidative phosphorylation. This metabolic reprogramming exposed a targetable metabolic vulnerability, leading to a sensitization of breast tumors to inhibitors of mitochondrial complex I (biguanides). Genetic inhibition of ShcA signaling in the Polyoma virus middle T (MT) breast cancer mouse model sensitized mammary tumors to biguanides during the earliest stages of breast cancer progression. Tumor initiation and growth were selectively and severely impaired in MT/ShcA-deficient animals. These data demonstrate that metabolic reprogramming is a key component of ShcA signaling and serves an unappreciated yet vital role during breast cancer initiation and progression. These data further unravel a novel interplay between ShcA and PGC-1α in the coordination of metabolic reprogramming and demonstrate the sensitivity of breast tumors to drugs targeting oxidative phosphorylation. This study uncovers a previously unrecognized mechanism that links aberrant RTK signaling with metabolic perturbations in breast cancer and exposes metabolic vulnerabilities that can be targeted by inhibitors of oxidative phosphorylation. .
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http://dx.doi.org/10.1158/0008-5472.CAN-17-3696DOI Listing
September 2018

Leveraging increased cytoplasmic nucleoside kinase activity to target mtDNA and oxidative phosphorylation in AML.

Blood 2017 05 10;129(19):2657-2666. Epub 2017 Mar 10.

Princess Margaret Cancer Centre, Toronto, ON, Canada.

Mitochondrial DNA (mtDNA) biosynthesis requires replication factors and adequate nucleotide pools from the mitochondria and cytoplasm. We performed gene expression profiling analysis of 542 human acute myeloid leukemia (AML) samples and identified 55% with upregulated mtDNA biosynthesis pathway expression compared with normal hematopoietic cells. Genes that support mitochondrial nucleotide pools, including mitochondrial nucleotide transporters and a subset of cytoplasmic nucleoside kinases, were also increased in AML compared with normal hematopoietic samples. Knockdown of cytoplasmic nucleoside kinases reduced mtDNA levels in AML cells, demonstrating their contribution in maintaining mtDNA. To assess cytoplasmic nucleoside kinase pathway activity, we used a nucleoside analog 2'3'-dideoxycytidine (ddC), which is phosphorylated to the activated antimetabolite, 2'3'-dideoxycytidine triphosphate by cytoplasmic nucleoside kinases. ddC is a selective inhibitor of the mitochondrial DNA polymerase γ. ddC was preferentially activated in AML cells compared with normal hematopoietic progenitor cells. ddC treatment inhibited mtDNA replication, oxidative phosphorylation, and induced cytotoxicity in a panel of AML cell lines. Furthermore, ddC preferentially inhibited mtDNA replication in a subset of primary human leukemia cells and selectively targeted leukemia cells while sparing normal progenitor cells. In animal models of human AML, treatment with ddC decreased mtDNA, electron transport chain proteins, and induced tumor regression without toxicity. ddC also targeted leukemic stem cells in secondary AML xenotransplantation assays. Thus, AML cells have increased cytidine nucleoside kinase activity that regulates mtDNA biogenesis and can be leveraged to selectively target oxidative phosphorylation in AML.
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http://dx.doi.org/10.1182/blood-2016-10-741207DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5766841PMC
May 2017

Metabolomics Analyses of Cancer Cells in Controlled Microenvironments.

Methods Mol Biol 2016 ;1458:273-90

Department of Biochemistry, McGill University, Montréal, QC, Canada, H3G 1Y6.

The tumor microenvironment is a complex and heterogeneous milieu in which cancer cells undergo metabolic reprogramming to fuel their growth. Cancer cell lines grown in vitro using traditional culture methods represent key experimental models to gain a mechanistic understanding of tumor biology. This protocol describes the use of gas chromatography-mass spectrometry (GC-MS) to assess metabolic changes in cancer cells grown under varied levels of oxygen and nutrients that may better mimic the tumor microenvironment. Intracellular metabolite changes, metabolite uptake and release, as well as stable isotope ((13)C) tracer analyses are done in a single experimental setup to provide an integrated understanding of metabolic adaptation. Overall, this chapter describes some essential tools and methods to perform comprehensive metabolomics analyses.
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http://dx.doi.org/10.1007/978-1-4939-3801-8_20DOI Listing
January 2018

High Sensitivity of an Ha-RAS Transgenic Model of Superficial Bladder Cancer to Metformin Is Associated with ∼240-Fold Higher Drug Concentration in Urine than Serum.

Mol Cancer Ther 2016 Mar 26;15(3):430-8. Epub 2016 Feb 26.

Department of Urology, University of California, Irvine, Orange, California. Department of Pharmacology, University of California, Irvine, Orange, California. Chao Family Comprehensive Cancer Center, University of California, Irvine, Orange, California.

While pharmacoepidemiologic and laboratory studies have supported the hypothesis that the antidiabetic drug metformin may be useful in treating or preventing cancer, there is limited evidence to suggest which specific cancer sites may be particularly sensitive. Sensitivity likely is determined both by features of tumor pathophysiology and by pharmacokinetic factors. We used UPII-mutant Ha-ras transgenic mice that develop hyperplasia and low-grade, papillary urothelial cell carcinoma to determine whether metformin has activity in a model of superficial bladder cancer. Metformin significantly improved survival, reduced urinary tract obstruction, reduced bladder weight (a surrogate for tumor volume), and led to clear activation of AMP α kinase and inhibition of mTOR signaling in neoplastic tissue. We investigated the basis of the unusual sensitivity of this model to metformin, and observed that following oral dosing, urothelium is exposed to drug concentrations via the urine that are approximately 240-fold higher than those in the circulation. In addition, we observed that bladder cancer cell lines (RT4, UMUC-3, and J82) with homozygous deletion of either TSC1 or PTEN are more sensitive to metformin than those (TEU2, TCCSUP, and HT1376) with wild-type TSC1 and PTEN genes. Our findings provide a strong rationale for clinical trials of oral metformin in treatment of superficial bladder cancer.
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http://dx.doi.org/10.1158/1535-7163.MCT-15-0714-TDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4783238PMC
March 2016

Mitochondrial Phosphoenolpyruvate Carboxykinase Regulates Metabolic Adaptation and Enables Glucose-Independent Tumor Growth.

Mol Cell 2015 Oct;60(2):195-207

Goodman Cancer Research Centre, McGill University, Montreal, QC H3A 1A3, Canada; Department of Physiology, McGill University, Montreal, QC H3G 1Y6, Canada. Electronic address:

Cancer cells adapt metabolically to proliferate under nutrient limitation. Here we used combined transcriptional-metabolomic network analysis to identify metabolic pathways that support glucose-independent tumor cell proliferation. We found that glucose deprivation stimulated re-wiring of the tricarboxylic acid (TCA) cycle and early steps of gluconeogenesis to promote glucose-independent cell proliferation. Glucose limitation promoted the production of phosphoenolpyruvate (PEP) from glutamine via the activity of mitochondrial PEP-carboxykinase (PCK2). Under these conditions, glutamine-derived PEP was used to fuel biosynthetic pathways normally sustained by glucose, including serine and purine biosynthesis. PCK2 expression was required to maintain tumor cell proliferation under limited-glucose conditions in vitro and tumor growth in vivo. Elevated PCK2 expression is observed in several human tumor types and enriched in tumor tissue from non-small-cell lung cancer (NSCLC) patients. Our results define a role for PCK2 in cancer cell metabolic reprogramming that promotes glucose-independent cell growth and metabolic stress resistance in human tumors.
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http://dx.doi.org/10.1016/j.molcel.2015.08.013DOI Listing
October 2015

Deletion of the gene encoding G0/G 1 switch protein 2 (G0s2) alleviates high-fat-diet-induced weight gain and insulin resistance, and promotes browning of white adipose tissue in mice.

Diabetologia 2015 Jan 9;58(1):149-57. Epub 2014 Nov 9.

Goodman Cancer Research Centre, McGill University, Room 616, 1160 Ave des Pins, Montréal, QC, H3A 1A3, Canada.

Aims/hypothesis: Obesity is a global epidemic resulting from increased energy intake, which alters energy homeostasis and results in an imbalance in fat storage and breakdown. G0/G1 switch gene 2 (G0s2) has been recently characterised in vitro as an inhibitor of adipose triglyceride lipase (ATGL), the rate-limiting step in fat catabolism. In the current study we aim to functionally characterise G0s2 within the physiological context of a mouse model.

Methods: We generated a mouse model in which G0s2 was deleted. The homozygous G0s2 knockout (G0s2 (-/-)) mice were studied over a period of 22 weeks. Metabolic variables were measured including body weight and body composition, food intake, glucose and insulin tolerance tests, energy metabolism and thermogenesis.

Results: We report that G0s2 inhibits ATGL and regulates lipolysis and energy metabolism in vivo. G0s2 (-/-) mice are lean, resistant to weight gain induced by a high-fat diet and are glucose tolerant and insulin sensitive. The white adipose tissue of G0s2 (-/-) mice has enhanced lipase activity and adipocytes showed enhanced stimulated lipolysis. Energy metabolism in the G0s2 (-/-) mice is shifted towards enhanced lipid metabolism and increased thermogenesis. G0s2 (-/-) mice showed enhanced cold tolerance and increased expression of thermoregulatory and oxidation genes within white adipose tissue, suggesting enhanced 'browning' of the white adipose tissue.

Conclusions/interpretation: Our data show that G0s2 is a physiological regulator of adiposity and energy metabolism and is a potential target in the treatment of obesity and insulin resistance.
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http://dx.doi.org/10.1007/s00125-014-3429-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5001162PMC
January 2015

Synergy between the NAMPT inhibitor GMX1777(8) and pemetrexed in non-small cell lung cancer cells is mediated by PARP activation and enhanced NAD consumption.

Cancer Res 2014 Nov 21;74(21):5948-54. Epub 2014 Aug 21.

Laboratory for Therapeutic Development, McGill University, Montreal, Québec, Canada.

GMX1778 and its prodrug GMX1777 represent a new class of cancer drugs that targets nicotinamide phosphoribosyltransferase (NAMPT) as a new strategy to interfere with biosynthesis of the key enzymatic cofactor NAD, which is critical for a number of cell functions, including DNA repair. Using a genome-wide synthetic lethal siRNA screen, we identified the folate pathway-related genes, deoxyuridine triphosphatase and dihydrofolate reductase, the silencing of which sensitized non-small cell lung carcinoma (NSCLC) cells to the cytotoxic effects of GMX. Pemetrexed is an inhibitor of dihydrofolate reductase currently used to treat patients with nonsquamous NSCLC. We found that combining pemetrexed with GMX1777 produced a synergistic therapeutic benefit in A549 and H1299 NSCLC cells in vitro and in a mouse A549 xenograft model of lung cancer. Pemetrexed is known to activate PARPs, thereby accelerating NAD consumption. Genetic or pharmacologic blockade of PARP activity inhibited this effect, impairing cell death by pemetrexed either alone or in combination with GMX1777. Conversely, inhibiting the base excision repair pathway accentuated NAD decline in response to GMX and the cytotoxicity of both agents either alone or in combination. These findings provide a mechanistic rationale for combining GMX1777 with pemetrexed as an effective new therapeutic strategy to treat nonsquamous NSCLC.
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http://dx.doi.org/10.1158/0008-5472.CAN-14-0809DOI Listing
November 2014

Stable isotope tracer analysis in isolated mitochondria from mammalian systems.

Metabolites 2014 Apr 10;4(2):166-83. Epub 2014 Apr 10.

Rosalind and Morris Goodman Cancer Research Centre, 1160 Pine Ave. West, Montréal H3A 1A3, Québec, Canada.

Mitochondria are a focal point in metabolism, given that they play fundamental roles in catabolic, as well as anabolic reactions. Alterations in mitochondrial functions are often studied in whole cells, and metabolomics experiments using 13C-labeled substrates, coupled with mass isotopomer distribution analyses, represent a powerful approach to study global changes in cellular metabolic activities. However, little is known regarding the assessment of metabolic activities in isolated mitochondria using this technology. Studies on isolated mitochondria permit the evaluation of whether changes in cellular metabolic activities are due to modifications in the intrinsic properties of the mitochondria. Here, we present a streamlined approach to accurately determine 13C, as well as 12C enrichments in isolated mitochondria from mammalian tissues or cultured cells by GC/MS. We demonstrate the relevance of this experimental approach by assessing the effects of drugs perturbing mitochondrial functions on the mass isotopomer enrichment of metabolic intermediates. Furthermore, we investigate 13C and 12C enrichments in mitochondria isolated from cancer cells given the emerging role of metabolic alterations in supporting tumor growth. This original method will provide a very sensitive tool to perform metabolomics studies on isolated mitochondria.
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http://dx.doi.org/10.3390/metabo4020166DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4101501PMC
April 2014

Oxidative metabolism enables Salmonella evasion of the NLRP3 inflammasome.

J Exp Med 2014 Apr 17;211(4):653-68. Epub 2014 Mar 17.

Department of Pathobiology, School of Veterinary Medicine; and 2 Immunology Graduate Group and 3 Cell and Molecular Biology Graduate Group, University of Pennsylvania, Kennett Square, PA 19104.

Microbial infection triggers assembly of inflammasome complexes that promote caspase-1-dependent antimicrobial responses. Inflammasome assembly is mediated by members of the nucleotide binding domain leucine-rich repeat (NLR) protein family that respond to cytosolic bacterial products or disruption of cellular processes. Flagellin injected into host cells by invading Salmonella induces inflammasome activation through NLRC4, whereas NLRP3 is required for inflammasome activation in response to multiple stimuli, including microbial infection, tissue damage, and metabolic dysregulation, through mechanisms that remain poorly understood. During systemic infection, Salmonella avoids NLRC4 inflammasome activation by down-regulating flagellin expression. Macrophages exhibit delayed NLRP3 inflammasome activation after Salmonella infection, suggesting that Salmonella may evade or prevent the rapid activation of the NLRP3 inflammasome. We therefore screened a Salmonella Typhimurium transposon library to identify bacterial factors that limit NLRP3 inflammasome activation. Surprisingly, absence of the Salmonella TCA enzyme aconitase induced rapid NLRP3 inflammasome activation. This inflammasome activation correlated with elevated levels of bacterial citrate, and required mitochondrial reactive oxygen species and bacterial citrate synthase. Importantly, Salmonella lacking aconitase displayed NLRP3- and caspase-1/11-dependent attenuation of virulence, and induced elevated serum IL-18 in wild-type mice. Together, our data link Salmonella genes controlling oxidative metabolism to inflammasome activation and suggest that NLRP3 inflammasome evasion promotes systemic Salmonella virulence.
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http://dx.doi.org/10.1084/jem.20130627DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3978275PMC
April 2014

Loss of the tumor suppressor LKB1 promotes metabolic reprogramming of cancer cells via HIF-1α.

Proc Natl Acad Sci U S A 2014 Feb 3;111(7):2554-9. Epub 2014 Feb 3.

Goodman Cancer Research Centre, McGill University, Montreal, QC, Canada H3A 1A3.

One of the major metabolic changes associated with cellular transformation is enhanced nutrient utilization, which supports tumor progression by fueling both energy production and providing biosynthetic intermediates for growth. The liver kinase B1 (LKB1) is a serine/threonine kinase and tumor suppressor that couples bioenergetics to cell-growth control through regulation of mammalian target of rapamycin (mTOR) activity; however, the influence of LKB1 on tumor metabolism is not well defined. Here, we show that loss of LKB1 induces a progrowth metabolic program in proliferating cells. Cells lacking LKB1 display increased glucose and glutamine uptake and utilization, which support both cellular ATP levels and increased macromolecular biosynthesis. This LKB1-dependent reprogramming of cell metabolism is dependent on the hypoxia-inducible factor-1α (HIF-1α), which accumulates under normoxia in LKB1-deficient cells and is antagonized by inhibition of mTOR complex I signaling. Silencing HIF-1α reverses the metabolic advantages conferred by reduced LKB1 signaling and impairs the growth and survival of LKB1-deficient tumor cells under low-nutrient conditions. Together, our data implicate the tumor suppressor LKB1 as a central regulator of tumor metabolism and growth control through the regulation of HIF-1α-dependent metabolic reprogramming.
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http://dx.doi.org/10.1073/pnas.1312570111DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3932920PMC
February 2014

The complete targeted profile of the organic acid intermediates of the citric acid cycle using a single stable isotope dilution analysis, sodium borodeuteride reduction and selected ion monitoring GC/MS.

Metabolomics 2013 17;9(5):1019-1030. Epub 2013 Apr 17.

Metabolomics Core Facility, Rosalind and Morris Goodman Cancer Research Centre, McGill University, 1160 Pine Avenue West, Room 418, Montreal, QC H3A 1A3 Canada.

The quantitative profiling of the organic acid intermediates of the citric acid cycle (CAC) presents a challenge due to the lack of commercially available internal standards for all of the organic acid intermediates. We developed an analytical method that enables the quantitation of all the organic acids in the CAC in a single stable isotope dilution GC/MS analysis with deuterium-labeled analogs used as internal standards. The unstable α-keto acids are rapidly reduced with sodium borodeuteride to the corresponding stable α-deutero-α-hydroxy acids and these, along with their unlabeled analogs and other CAC organic acid intermediates, are converted to their -butyldimethylsilyl derivatives. Selected ion monitoring is employed with electron ionization. We validated this method by treating an untransformed mouse mammary epithelial cell line with well-known mitochondrial toxins affecting the electron transport chain and ATP synthase, which resulted in profound perturbations of the concentration of CAC intermediates.
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http://dx.doi.org/10.1007/s11306-013-0521-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3855487PMC
April 2013

PGC-1α supports glutamine metabolism in breast cancer.

Cancer Metab 2013 Dec 5;1(1):22. Epub 2013 Dec 5.

Goodman Cancer Research Centre, McGill University, 1160 Pine Ave. West, Montréal, PQ H3A 1A3, Canada.

Background: Glutamine metabolism is a central metabolic pathway in cancer. Recently, reductive carboxylation of glutamine for lipogenesis has been shown to constitute a key anabolic route in cancer cells. However, little is known regarding central regulators of the various glutamine metabolic pathways in cancer cells.

Methods: The impact of PGC-1α and ERRα on glutamine enzyme expression was assessed in ERBB2+ breast cancer cell lines with quantitative RT-PCR, chromatin immunoprecipitation, and immunoblotting experiments. Glutamine flux was quantified using 13C-labeled glutamine and GC/MS analyses. Functional assays for lipogenesis were performed using 14C-labeled glutamine. The expression of glutamine metabolism genes in breast cancer patients was determined by bioinformatics analyses using The Cancer Genome Atlas.

Results: We show that the transcriptional coactivator PGC-1α, along with the transcription factor ERRα, is a positive regulator of the expression of glutamine metabolism genes in ERBB2+ breast cancer. Indeed, ERBB2+ breast cancer cells with increased expression of PGC-1α display elevated expression of glutamine metabolism genes. Furthermore, ERBB2+ breast cancer cells with reduced expression of PGC-1α or when treated with C29, a pharmacological inhibitor of ERRα, exhibit diminished expression of glutamine metabolism genes. The biological relevance of the control of glutamine metabolism genes by the PGC-1α/ERRα axis is demonstrated by consequent regulation of glutamine flux through the citric acid cycle. PGC-1α and ERRα regulate both the canonical citric acid cycle (forward) and the reductive carboxylation (reverse) fluxes; the latter can be used to support de novo lipogenesis reactions, most notably in hypoxic conditions. Importantly, murine and human ERBB2+ cells lines display a significant dependence on glutamine availability for their growth. Finally, we show that PGC-1α expression is positively correlated with that of the glutamine pathway in ERBB2+ breast cancer patients, and high expression of this pathway is associated with reduced patient survival.

Conclusions: These data reveal that the PGC-1α/ERRα axis is a central regulator of glutamine metabolism in ERBB2+ breast cancer. This novel regulatory link, as well as the marked reduction in patient survival time associated with increased glutamine pathway gene expression, suggests that targeting glutamine metabolism may have therapeutic potential in the treatment of ERBB2+ breast cancer.
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http://dx.doi.org/10.1186/2049-3002-1-22DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4178216PMC
December 2013

LKB1 is a central regulator of tumor initiation and pro-growth metabolism in ErbB2-mediated breast cancer.

Cancer Metab 2013 Aug 14;1(1):18. Epub 2013 Aug 14.

Goodman Cancer Research Centre, McGill University, Montréal, Québec, Canada.

Background: Germline and somatic mutations in STK11, the gene encoding the serine/threonine kinase LKB1, are strongly associated with tumorigenesis. While loss of LKB1 expression has been linked to breast cancer, the mechanistic role of LKB1 in regulating breast cancer development, metastasis, and tumor metabolism has remained unclear.

Methods: We have generated and analyzed transgenic mice expressing ErbB2 in the mammary epithelium of LKB1 wild-type or LKB1-deficient mice. We have also utilized ErbB2-expressing breast cancer cells in which LKB1 levels have been reduced using shRNA approaches. These transgenic and xenograft models were characterized for the effects of LKB1 loss on tumor initiation, growth, metastasis and tumor cell metabolism.

Results: We demonstrate that loss of LKB1 promotes tumor initiation and induces a characteristic shift to aerobic glycolysis ('Warburg effect') in a model of ErbB2-mediated breast cancer. LKB1-deficient breast cancer cells display enhanced early tumor growth coupled with increased cell migratory and invasive properties in vitro. We show that ErbB2-positive tumors deficient for LKB1 display a pro-growth molecular and phenotypic signature characterized by elevated Akt/mTOR signaling, increased glycolytic metabolism, as well as increased bioenergetic markers both in vitro and in vivo. We also demonstrate that mTOR contributes to the metabolic reprogramming of LKB1-deficient breast cancer, and is required to drive glycolytic metabolism in these tumors; however, LKB1-deficient breast cancer cells display reduced metabolic flexibility and increased apoptosis in response to metabolic perturbations.

Conclusions: Together, our data suggest that LKB1 functions as a tumor suppressor in breast cancer. Loss of LKB1 collaborates with activated ErbB2 signaling to drive breast tumorigenesis and pro-growth metabolism in the resulting tumors.
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http://dx.doi.org/10.1186/2049-3002-1-18DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4178213PMC
August 2013

mTORC1 controls mitochondrial activity and biogenesis through 4E-BP-dependent translational regulation.

Cell Metab 2013 Nov;18(5):698-711

Department of Biochemistry, McGill University, Montreal, QC H3A 1A3, Canada; Goodman Cancer Research Centre, McGill University, Montreal, QC H3A 1A3, Canada.

mRNA translation is thought to be the most energy-consuming process in the cell. Translation and energy metabolism are dysregulated in a variety of diseases including cancer, diabetes, and heart disease. However, the mechanisms that coordinate translation and energy metabolism in mammals remain largely unknown. The mechanistic/mammalian target of rapamycin complex 1 (mTORC1) stimulates mRNA translation and other anabolic processes. We demonstrate that mTORC1 controls mitochondrial activity and biogenesis by selectively promoting translation of nucleus-encoded mitochondria-related mRNAs via inhibition of the eukaryotic translation initiation factor 4E (eIF4E)-binding proteins (4E-BPs). Stimulating the translation of nucleus-encoded mitochondria-related mRNAs engenders an increase in ATP production capacity, a required energy source for translation. These findings establish a feed-forward loop that links mRNA translation to oxidative phosphorylation, thereby providing a key mechanism linking aberrant mTOR signaling to conditions of abnormal cellular energy metabolism such as neoplasia and insulin resistance.
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http://dx.doi.org/10.1016/j.cmet.2013.10.001DOI Listing
November 2013

AMPK is a negative regulator of the Warburg effect and suppresses tumor growth in vivo.

Cell Metab 2013 Jan 27;17(1):113-24. Epub 2012 Dec 27.

Department of Physiology, McGill University, Montreal, QC, H3G 1Y6, Canada.

AMPK is a metabolic sensor that helps maintain cellular energy homeostasis. Despite evidence linking AMPK with tumor suppressor functions, the role of AMPK in tumorigenesis and tumor metabolism is unknown. Here we show that AMPK negatively regulates aerobic glycolysis (the Warburg effect) in cancer cells and suppresses tumor growth in vivo. Genetic ablation of the α1 catalytic subunit of AMPK accelerates Myc-induced lymphomagenesis. Inactivation of AMPKα in both transformed and nontransformed cells promotes a metabolic shift to aerobic glycolysis, increased allocation of glucose carbon into lipids, and biomass accumulation. These metabolic effects require normoxic stabilization of the hypoxia-inducible factor-1α (HIF-1α), as silencing HIF-1α reverses the shift to aerobic glycolysis and the biosynthetic and proliferative advantages conferred by reduced AMPKα signaling. Together our findings suggest that AMPK activity opposes tumor development and that its loss fosters tumor progression in part by regulating cellular metabolic pathways that support cell growth and proliferation.
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http://dx.doi.org/10.1016/j.cmet.2012.12.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3545102PMC
January 2013

Alterations in cellular energy metabolism associated with the antiproliferative effects of the ATM inhibitor KU-55933 and with metformin.

PLoS One 2012 21;7(11):e49513. Epub 2012 Nov 21.

Department of Oncology, McGill University, Montreal, Quebec, Canada.

KU-55933 is a specific inhibitor of the kinase activity of the protein encoded by Ataxia telangiectasia mutated (ATM), an important tumor suppressor gene with key roles in DNA repair. Unexpectedly for an inhibitor of a tumor suppressor gene, KU-55933 reduces proliferation. In view of prior preliminary evidence suggesting defective mitochondrial function in cells of patients with Ataxia Telangiectasia (AT), we examined energy metabolism of cells treated with KU-55933. The compound increased AMPK activation, glucose uptake and lactate production while reducing mitochondrial membrane potential and coupled respiration. The stimulation of glycolysis by KU-55933 did not fully compensate for the reduction in mitochondrial functions, leading to decreased cellular ATP levels and energy stress. These actions are similar to those previously described for the biguanide metformin, a partial inhibitor of respiratory complex I. Both compounds decreased mitochondrial coupled respiration and reduced cellular concentrations of fumarate, malate, citrate, and alpha-ketogluterate. Succinate levels were increased by KU-55933 levels and decreased by metformin, indicating that the effects of ATM inhibition and metformin are not identical. These observations suggest a role for ATM in mitochondrial function and show that both KU-55933 and metformin perturb the TCA cycle as well as oxidative phosphorylation.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0049513PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3504012PMC
May 2013

PGC-1α promotes the growth of ErbB2/Neu-induced mammary tumors by regulating nutrient supply.

Cancer Res 2012 Mar 19;72(6):1538-46. Epub 2012 Jan 19.

Department of Biochemistry and Goodman Cancer Research Centre, McGill University, Montreal, Quebec, Canada.

Cancer cells display an increased reliance on glycolysis despite the presence of sufficient oxygen levels to support mitochondrial functions. In this study, we asked whether ameliorating mitochondrial functions in cancer cells might limit their proliferative capacity. Specifically, we increased mitochondrial metabolism in a murine cellular model of ErbB2/Neu-induced breast cancer by ectopically expressing the transcriptional coactivator peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α), a master regulator of mitochondrial metabolism. As predicted, ErbB2/Neu cells ectopically expressing PGC-1α displayed an increased level of mitochondrial metabolism and reduced proliferative capacity in vitro, compared with controls. In contrast, ErbB2/Neu cells ectopically expressing PGC-1α formed larger tumors in vivo. These tumors exhibited increased concentrations of glucose and the angiogenic factor VEGF as well as higher expression of ErbB2/Neu compared with controls. We discovered that ErbB2/Neu levels were sensitive to nutrient availability, such that reduced glucose concentrations resulted in diminished ErbB2/Neu protein levels. Therefore, our data indicate that PGC-1α prevents the nutrient-mediated downregulation of ErbB2/Neu in tumors by increasing glucose supply. Mechanistic investigations revealed that the regulation of ErbB2/Neu levels by glucose was mediated by the unfolded protein response (UPR). Incubation of ErbB2/Neu-induced breast cancer cells in limited glucose concentrations or with drugs that activate the UPR led to significant reductions in ErbB2/Neu protein levels. Also, ErbB2/Neu-induced tumors ectopically expressing PGC-1α displayed lowered UPR activation compared with controls. Together, our findings uncover an unexpected link between PGC-1α-mediated nutrient availability, UPR, and ErbB2/Neu levels.
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http://dx.doi.org/10.1158/0008-5472.CAN-11-2967DOI Listing
March 2012

Electronic referencing techniques for quantitative NMR: pitfalls and how to avoid them using amplitude-corrected referencing through signal injection.

Anal Chem 2008 Nov 10;80(21):8320-3. Epub 2008 Oct 10.

Varian MR Systems, 3120 Hansen Way M/S D-298 Palo Alto California, California 94304, USA.

NMR spectroscopy can be a superior analytical technique for quantification of compounds dissolved in solution. Traditionally a chemical reference standard of known concentration is added to the sample. The concentration of the solute can then be determined by comparing the signal integrals. However, it can be inconvenient or impossible to use internal references. Electronic referencing was developed to circumvent problems with internal standards and has been used successfully in well-controlled situations. However, it is not always possible or convenient to have samples where the dielectric sample properties do not change from one to the next. We propose a modification of the old electronic referencing technique that takes into account the electronic changes between dissimilar samples. We have called this new technique Amplitude-corrected Referencing Through Signal Injection or ARTSI.
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http://dx.doi.org/10.1021/ac800865cDOI Listing
November 2008

Improving NMR sensitivity by use of salt-tolerant cryogenically cooled probes.

Anal Bioanal Chem 2007 Jan 25;387(2):529-32. Epub 2006 Nov 25.

Pfizer Global Research and Development, 2800 Plymouth Road, Ann Arbor, MI 48105, USA.

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http://dx.doi.org/10.1007/s00216-006-0982-4DOI Listing
January 2007
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