Abstract The approval of bedaquiline (BDQ) for the treatment of tuberculosis has generated substantial interest in inhibiting energy metabolism as a therapeutic paradigm. However, it is not known precisely how BDQ triggers cell death in Mycobacterium tuberculosis ( Mtb) . Using 13 C isotopomer analysis, we show that BDQ-treated Mtb redirects central carbon metabolism to induce a metabolically vulnerable state susceptible to genetic disruption of glycolysis and gluconeogenesis. Metabolic flux profiles indicate that BDQ-treated Mtb is dependent on glycolysis for ATP production, operates a bifurcated TCA cycle by increasing flux through the glyoxylate shunt, and requires enzymes of the anaplerotic node and methylcitrate cycle. Targeting oxidative phosphorylation (OXPHOS) with BDQ and simultaneously inhibiting substrate level phosphorylation via genetic disruption of glycolysis leads to rapid sterilization. Our findings provide insight into the metabolic mechanism of BDQ-induced cell death and establish a paradigm for the development of combination therapies that target OXPHOS and glycolysis.
Stahl is a siphophage active against Bacillus megaterium, a Gram-positive bacterium often used as a model system in research and as a protein production strain in industrial applications. Here, we present the complete annotated genome of phage Stahl and describe its major features.
Abstract INTRODUCTION: Strong clinical evidence demonstrates a link between acute bacterial infection and metastasis. We and others have shown that activation of certain membrane pattern recognition receptors (PRRs), such as Toll-like receptors, on cancer cells can be implicated in this process. There is emerging data that a cytoplasmic PRR, the nucleotide oligomerization domain receptor 1 (NOD1), may also play an important and complementary role in the immune response to bacterial infection, however its role in cancer progression is entirely unknown. We sought to determine the influence of NOD1 activation on metastasis. METHODS: NOD1 expression in human and murine colon (HT29, MC38) and lung (A549, H59) cancer cells were confirmed using flow cytometry (FC) and immunoblotting (WB). A series of in vitro and in vivo functional assays, including adhesion, migration and hepatic intravital microscopy (IVM), was conducted to assess the effect of NOD1 activation and inhibition. C12-iE-DAP, a highly selective NOD1 ligand derived from gram-negative bacterial wall, was used to simulate NOD1-activation under infectious condition. ML130, a specific NOD1 inhibitor, was used to block C12-iE-DAP activation. Stable knockdown (KD) of NOD1 in HT29 and A549 cells were constructed with shRNA lentiviral transduction and the functional assays were thus repeated. The predominant signaling pathway, downstream cytokines and cell adhesion molecules of NOD1-activation were identified using WB in the presence of kinase inhibitors. RESULTS: WB and FC showed abundant NOD1 expression in all tested cell lines. Cancer cells stimulated with C12-iE-DAP doubled the in vitro adhesion to collagen I, IV and fibronectin, as well as in vitro migration, an effect completely attenuated with ML130 inhibition and NOD1 knockdown. Using a murine hepatic adhesion assay under IVM, we observed a doubling in the amount of in vivo capture of cancer cells within hepatic sinusoids of C57BL6 mice in the C12-iE-DAP group compared to control, an effect again abrogated by ML130 inhibition and NOD1 knockdown. Immunoblotting using HT29 cells under a panel of kinase inhibitors revealed that NOD1 activation is p38 dependent. Subsequently, the use of p38 inhibitor, BIRB0796, abolished C12-iE-DAP mediated adhesion to collagen I and fibronectin. Using human cytokine quantification array, we determined that NOD1 activation led to increase in IL-8, 15, MCP1 and RANTES, all of which have been shown to link to cancer progression or to chemoattract neutrophils, which we have recently shown to mediate metastasis. CONCLUSION: Our data demonstrate that NOD1 activation by the gram-negative bacterial wall component, C12-iE-DAP is important in enhancing the metastatic potential of cancer cells, and its mechanism is dependent on p38 activation and the upregulation of downstream cytokines. This is the first study to implicate NOD1 in metastasis, and thus identify this receptor as a putative therapeutic target. Citation Format: Henry Jiang, Sara Najmeh, Julie Berube, Arielle Leone, Paul Savage, Betty Giannias, France Bourdeau, Simon Rousseau, Morag Park, Lorenzo Edwin Ferri. NOD1 augments cancer cell metastatic potential through p38 MAP kinase activation. [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 3162. doi:10.1158/1538-7445.AM2015-3162
Catalytic promiscuity is the coincidental ability to catalyze nonbiological reactions in the same active site as the native biological reaction. Several lines of evidence show that catalytic promiscuity plays a role in the evolution of new enzyme functions. Thus, studying catalytic promiscuity can help identify structural features that predispose an enzyme to evolve new functions. This study identifies a potentially preadaptive residue in a promiscuous N-succinylamino acid racemase/o-succinylbenzoate synthase (NSAR/OSBS) enzyme from Amycolatopsis sp. T-1-60. This enzyme belongs to a branch of the OSBS family which includes many catalytically promiscuous NSAR/OSBS enzymes. R266 is conserved in all members of the NSAR/OSBS subfamily. However, the homologous position is usually hydrophobic in other OSBS subfamilies, whose enzymes lack NSAR activity. The second-shell amino acid R266 is close to the catalytic acid/base K263, but it does not contact the substrate, suggesting that R266 could affect the catalytic mechanism. Mutating R266 to glutamine in Amycolatopsis NSAR/OSBS profoundly reduces NSAR activity but moderately reduces OSBS activity. This is due to a 1000-fold decrease in the rate of proton exchange between the substrate and the general acid/base catalyst K263. This mutation is less deleterious for the OSBS reaction because K263 forms a cation−π interaction with the OSBS substrate and/or the intermediate, rather than acting as a general acid/base catalyst. Together, the data explain how R266 contributes to NSAR reaction specificity and was likely an essential preadaptation for the evolution of NSAR activity.
In mammals, there are four p38 protein kinases: p38α, p38β, p38γ and p38δ. p38β was identified in 1996 as a closely related protein kinase of p38α, sharing 74% sequence identity and the Thr-Gly-Tyr dual phosphorylation motif characteristic of all p38 MAPKs. p38β is widely distributed in cells and tissues, but less so than p38α; p38β is particularly abundant in endothelial cells. p38β is activated in vivo by dual phosphorylation at Thr180 and Tyr182 by the MAP2K, MKK3 and MKK6 in response to a multitude of stimuli including environmental stressors, cytokines and growth factors. p38β can be dephosphorylated on both its Thr and Tyr residues by Dual-Specificity Phosphatases. p38β, like p38α, is targeted by a class of pyridinyl imidazole drugs that do not target the other two p38 MAPKs. These compounds were invaluable in discovering functions regulated by p38α and p38β. However, they do not permit to distinguish functions mediated by p38β from those regulated by p38α. This distinction has been made possible by the use of genetically engineered mice. p38β-deficient mice are not embryonic lethal such as those lacking p38α. However ectopic expression of p38β can rescue the lethality of p38α-deficiency. This suggests that p38α is the “dominant” form but that functional redundancy exists between the two related protein kinase. p38β has been shown to play specific roles in gene expression, regulation of cell death, cell differentiation and neuropathic pain. However, p38β is not involved in transducing pro-inflammatory signals, myogenesis or cell motility, when p38α is present.
Targeting the dynamic tumor immune microenvironment can provide effective therapeutic strategies for cancer. Neutrophils (polymorphonuclear neutrophils, PMNs) are the predominant circulating leukocyte population in humans and are vital to fight infection. Despite mounting evidence that PMNs can promote tumor progression, depleting PMNs is not a viable therapeutic option. Neutrophil extracellular traps (NETs) are networks of extracellular neutrophil DNA fibers that are capable of trapping tumor cells and promoting their growth and their metastasis. Targeting NETs can therefore be a potentially successful therapeutic option to block the tumor promoting functions of PMNs. Here we demonstrate that circulating NET levels are elevated in esophageal, gastric and lung cancer patients compared to healthy controls. This increase correlates with disease stage and NET levels are independent predictors of advanced stage. Using pre-clinical murine models of lung and colon cancer, we observe elevated NET levels in tumor bearing mice compared to non-tumor bearing mice; these levels correlated with tumor size. NET levels significantly decrease following tumor resection or treatment with DNase1, a NET degrader, or neutrophil elastase inhibitor (NEi), a NET inhibitor. NET levels do not rise following tumor inoculation in peptidyl arginine deiminase-IV knock out (PAD4-/-) mice; PAD4 being an enzyme essential for citrullination of histones, a crucial step in NET release. Moreover, PMNs from tumor bearing mice are more primed for NETosis than PMNs from non-tumor bearing mice or NEi-treated or PAD4-/- tumor bearing mice. Finally, elevated in vivo hepatic adhesion and spontaneous liver and lung metastases are observed in tumor bearing mice compared to DNase1- or NEi-treated or PAD4-/- tumor bearing mice. Therefore, inhibiting NETs represents a promising strategy to impede metastatic dissemination in several types of cancer patients.Citation Format: Roni F. Rayes, Jack G. Mouhanna, Ioana Nicolau, Phil Vourtzoumis, Carson Wong, Jules Eustache, France Bourdeau, Betty Giannias, Aya Siblini, Emma Lee, Veena Sangwan, Simon Rousseau, Daniela Quail, Logan Walsh, Nicholas Bertos, Jonathan Cools-Lartigue, Lorenzo E. Ferri, Jonathan D. Spicer. Primary tumors induce neutrophil extracellular traps with targetable metastasis promoting effects [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1508.
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