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Sharma A, Jyotsana N, Lai CK, Chaturvedi A, Gabdoulline R, Görlich K, Murphy C, Blanchard JE, Ganser A, Brown E, Hassell JA, Humphries RK, Morgan M, Heuser M. Pyrimethamine as a Potent and Selective Inhibitor of Acute Myeloid Leukemia Identified by High-throughput Drug Screening. Curr Cancer Drug Targets 2017; 16:818-828. [PMID: 27321378 DOI: 10.2174/1568009616666160617103301] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Revised: 05/30/2016] [Accepted: 06/12/2016] [Indexed: 11/22/2022]
Abstract
Hematopoietic stem and progenitor cell differentiation are blocked in acute myeloid leukemia (AML) resulting in cytopenias and a high risk of death. Most patients with AML become resistant to treatment due to lack of effective cytotoxic and differentiation promoting compounds. High MN1 expression confers poor prognosis to AML patients and induces resistance to cytarabine and alltrans-retinoic acid (ATRA) induced differentiation. Using a high-throughput drug screening, we identified the dihydrofolate reductase (DHFR) antagonist pyrimethamine to be a potent inducer of apoptosis and differentiation in several murine and human leukemia cell lines. Oral pyrimethamine treatment was effective in two xenograft mouse models and specifically targeted leukemic cells in human AML cell lines and primary patient cells, while CD34+ cells from healthy donors were unaffected. The antileukemic effects of PMT could be partially rescued by excess folic acid, suggesting an oncogenic function of folate metabolism in AML. Thus, our study identifies pyrimethamine as a candidate drug that should be further evaluated in AML treatment.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | - Michael Heuser
- Department of Hematology, Hemostasis, Oncology and Stem cell Transplantation, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany.
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Bharat A, Blanchard JE, Brown ED. A high-throughput screen of the GTPase activity of Escherichia coli EngA to find an inhibitor of bacterial ribosome biogenesis. ACTA ACUST UNITED AC 2013; 18:830-6. [PMID: 23606650 DOI: 10.1177/1087057113486001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The synthesis of ribosomes is an essential process, which is aided by a variety of trans-acting factors in bacteria. Among these is a group of GTPases essential for bacterial viability and emerging as promising targets for new antibacterial agents. Herein, we describe a robust high-throughput screening process for inhibitors of one such GTPase, the Escherichia coli EngA protein. The primary screen employed an assay of phosphate production in a 384-well density. Reaction conditions were chosen to maximize sensitivity for the discovery of competitive inhibitors while maintaining a strong signal amplitude and low noise. In a pilot screen of 31,800 chemical compounds, 44 active compounds were identified. Furthermore, we describe the elimination of nonspecific inhibitors that were detergent sensitive or reactive as well as those that interfered with the high-throughput phosphate assay. Four inhibitors survived these common counterscreens for nonspecificity, but these chemicals were also inhibitors of the unrelated enzyme dihydrofolate reductase, suggesting that they too were promiscuously active. The high-throughput screen of the EngA protein described here provides a meticulous pilot study in the search for specific inhibitors of GTPases involved in ribosome biogenesis.
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Affiliation(s)
- Amrita Bharat
- 1M. G. DeGroote Institute for Infectious Disease Research and Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada
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Diallo JS, Le Boeuf F, Lai F, Cox J, Vaha-Koskela M, Abdelbary H, MacTavish H, Waite K, Falls T, Wang J, Brown R, Blanchard JE, Brown ED, Kirn DH, Hiscott J, Atkins H, Lichty BD, Bell JC. A high-throughput pharmacoviral approach identifies novel oncolytic virus sensitizers. Mol Ther 2010; 18:1123-9. [PMID: 20389287 PMCID: PMC2889739 DOI: 10.1038/mt.2010.67] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2010] [Accepted: 03/16/2010] [Indexed: 12/18/2022] Open
Abstract
Oncolytic viruses (OVs) are promising anticancer agents but like other cancer monotherapies, the genetic heterogeneity of human malignancies can lead to treatment resistance. We used a virus/cell-based assay to screen diverse chemical libraries to identify small molecules that could act in synergy with OVs to destroy tumor cells that resist viral infection. Several molecules were identified that aid in viral oncolysis, enhancing virus replication and spread as much as 1,000-fold in tumor cells. One of these molecules we named virus-sensitizers 1 (VSe1), was found to target tumor innate immune response and could enhance OV efficacy in animal tumor models and within primary human tumor explants while remaining benign to normal tissues. We believe this is the first example of a virus/cell-based "pharmacoviral" screen aimed to identify small molecules that modulate cellular response to virus infection and enhance oncolytic virotherapy.
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Affiliation(s)
- Jean-Simon Diallo
- Ottawa Hospital Research Institute, Center for Cancer Therapeutics, Ottawa, Ontario, Canada
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Tropak MB, Kornhaber GJ, Rigat BA, Maegawa GH, Buttner JD, Blanchard JE, Murphy C, Tuske SJ, Coales SJ, Hamuro Y, Brown ED, Mahuran DJ. Identification of pharmacological chaperones for Gaucher disease and characterization of their effects on beta-glucocerebrosidase by hydrogen/deuterium exchange mass spectrometry. Chembiochem 2009; 9:2650-62. [PMID: 18972510 DOI: 10.1002/cbic.200800304] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Point mutations in beta-glucocerebrosidase (GCase) can result in a deficiency of both GCase activity and protein in lysosomes thereby causing Gaucher Disease (GD). Enzyme inhibitors such as isofagomine, acting as pharmacological chaperones (PCs), increase these levels by binding and stabilizing the native form of the enzyme in the endoplasmic reticulum (ER), and allow increased lysosomal transport of the enzyme. A high-throughput screen of the 50,000-compound Maybridge library identified two, non-carbohydrate-based inhibitory molecules, a 2,4-diamino-5-substituted quinazoline (IC(50) 5 microM) and a 5-substituted pyridinyl-2-furamide (IC(50) 8 microM). They raised the levels of functional GCase 1.5-2.5-fold in N370S or F213I GD fibroblasts. Immunofluorescence confirmed that treated GD fibroblasts had decreased levels of GCase in their ER and increased levels in lysosomes. Changes in protein dynamics, monitored by hydrogen/deuterium-exchange mass spectrometry, identified a domain III active-site loop (residues 243-249) as being significantly stabilized upon binding of isofagomine or either of these two new compounds; this suggests a common mechanism for PC enhancement of intracellular transport.
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Affiliation(s)
- Michael B Tropak
- Research Institute, Hospital for Sick Children, 555 University Avenue, Toronto, Ontario M5G1X8, Canada
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Tropak MB, Kornhaber GJ, Rigat BA, Maegawa GH, Buttner JD, Blanchard JE, Murphy C, Tuske SJ, Coales SJ, Hamuro Y, Brown ED, Mahuran DJ. Cover Picture: Identification of Pharmacological Chaperones for Gaucher Disease and Characterization of Their Effects on β-Glucocerebrosidase by Hydrogen/Deuterium Exchange Mass Spectrometry (ChemBioChem 16/2008). Chembiochem 2008. [DOI: 10.1002/cbic.200890061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Ejim LJ, Blanchard JE, Koteva KP, Sumerfield R, Elowe NH, Chechetto JD, Brown ED, Junop MS, Wright GD. Inhibitors of Bacterial Cystathionine β-Lyase: Leads for New Antimicrobial Agents and Probes of Enzyme Structure and Function. J Med Chem 2007; 50:755-64. [PMID: 17300162 DOI: 10.1021/jm061132r] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The biosynthesis of methionine is an attractive antibiotic target given its importance in protein and DNA metabolism and its absence in mammals. We have performed a high-throughput screen of the methionine biosynthesis enzyme cystathionine beta-lyase (CBL) against a library of 50 000 small molecules and have identified several compounds that inhibit CBL enzyme activity in vitro. These hit molecules were of two classes: those that blocked CBL activity with mixed steady-state inhibition and those that covalently interacted with the enzyme at the active site pyridoxal phosphate cofactor with slow-binding inhibition kinetics. We determined the crystal structure of one of the slow-binding inhibitors in complex with CBL and used this structure as a guide in the synthesis of a small, focused library of analogues, some of which had improved enzyme inhibition properties. These studies provide the first lead molecules for antimicrobial agents that target cystathionine beta-lyase in methionine biosynthesis.
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Affiliation(s)
- Linda J Ejim
- Antimicrobial Research Centre, McMaster High Throughput Screening Laboratory, Department of Biochemistry and Biomedical Sciences, McMaster University, Ontario L8N 3Z5, Canada
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Elowe NH, Blanchard JE, Cechetto JD, Brown ED. Experimental Screening of Dihydrofolate Reductase Yields a “Test Set” of 50,000 Small Molecules for a Computational Data-Mining and Docking Competition. ACTA ACUST UNITED AC 2005; 10:653-7. [PMID: 16170050 DOI: 10.1177/1087057105281173] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
High-throughput screening (HTS) generates an abundance of data that are a valuable resource to be mined. Dockers and data miners can use “real-world” HTS data to test and further develop their tools. A screen of 50,000 diverse small molecules was carried out against Escherichia coli dihydrofolate reductase (DHFR) and compared with a previous screen of 50,000 compounds against the same target. Identical assays and conditions were maintained for both studies. Prior to the completion of the second screen, the original screening data were publicly released for use as a “training set,” and computational chemists and data analysts were challenged to predict the activity of compounds in this second “test set.” Upon completion, the primary screen of the test set generated no potent inhibitors of DHFR activity.
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Affiliation(s)
- Nadine H Elowe
- McMaster HTS Lab, Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada L8N 3Z5
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Blanchard JE, Elowe NH, Huitema C, Fortin PD, Cechetto JD, Eltis LD, Brown ED. High-throughput screening identifies inhibitors of the SARS coronavirus main proteinase. ACTA ACUST UNITED AC 2005; 11:1445-53. [PMID: 15489171 PMCID: PMC7134594 DOI: 10.1016/j.chembiol.2004.08.011] [Citation(s) in RCA: 157] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2004] [Revised: 07/20/2004] [Accepted: 08/10/2004] [Indexed: 11/24/2022]
Abstract
The causative agent of severe acute respiratory syndrome (SARS) has been identified as a novel coronavirus, SARS-CoV. The main proteinase of SARS-CoV, 3CLpro, is an attractive target for therapeutics against SARS owing to its fundamental role in viral replication. We sought to identify novel inhibitors of 3CLpro to advance the development of appropriate therapies in the treatment of SARS. 3CLpro was cloned, expressed, and purified from the Tor2 isolate. A quenched fluorescence resonance energy transfer assay was developed for 3CLpro to screen the proteinase against 50,000 drug-like small molecules on a fully automated system. The primary screen identified 572 hits; through a series of virtual and experimental filters, this number was reduced to five novel small molecules that show potent inhibitory activity (IC50 = 0.5-7 microM) toward SARS-CoV 3CLpro.
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Affiliation(s)
- Jan E Blanchard
- McMaster High Throughput Screening Laboratory, Department of Biochemistry, McMaster University, Hamilton, Ontario L8N 3Z5, Canada
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Blanchard JE, Withers SG. Rapid screening of the aglycone specificity of glycosidases: applications to enzymatic synthesis of oligosaccharides. Chem Biol 2001; 8:627-33. [PMID: 11451664 DOI: 10.1016/s1074-5521(01)00038-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
BACKGROUND Retaining glycosidases can catalyse glycosidic bond formation through transglycosylation from a donor sugar to an acceptor bound in the aglycone site. The aglycone specificity of a glycosidase is not easily determined, thereby complicating the choice of the most appropriate glycosidase for use as a catalyst for transglycosylation. We have developed a strategy to rapidly screen the aglycone specificity of a glycosidase and thereby determine which enzymes are best suited to catalyse specific transglycosylation reactions. RESULTS The reactivation, or turnover, of a glycosidase trapped as a fluoroglycosyl-enzyme species is accelerated in the presence of a compound that productively binds to the aglycone site. This methodology was used to rapidly screen six glycosidases with 44 potential acceptor sugars. Validation of the screening strategy was demonstrated by the identification of products formed from a transglycosylation reaction with positively screened acceptors for four of the enzymes studied. CONCLUSIONS The aglycone specificity of a glycosidase can be rapidly evaluated and requires only an appropriate fluorosugar inactivator, a substrate for assay of activity and a library of compounds for screening.
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Affiliation(s)
- J E Blanchard
- Protein Engineering Network of Centres of Excellence of Canada and the Department of Chemistry, University of British Columbia, V6T 1Z1, Vancouver, BC, Canada
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Blanchard JE, Gal L, He S, Foisy J, Warren RA, Withers SG. The identification of the catalytic nucleophiles of two beta-galactosidases from glycoside hydrolase family 35. Carbohydr Res 2001; 333:7-17. [PMID: 11423106 DOI: 10.1016/s0008-6215(01)00108-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The beta-galactosidases from Xanthomonas manihotis (beta-Gal Xmn) and Bacillus circulans (beta-Gal-3 Bcir) are retaining glycosidases that hydrolyze glycosidic bonds through a double displacement mechanism involving a covalent glycosyl-enzyme intermediate. The mechanism-based inactivator 2,4-dinitrophenyl 2-deoxy-2-fluoro-beta-D-galactopyranoside was shown to inactivate beta-Gal Xmn and beta-Gal-3 Bcir through the accumulation of 2-deoxy-2-fluorogalactosyl enzyme intermediates with half lives of 40 and 625 h, respectively. Peptic digestion of these labeled enzymes and analysis by LC-MS identified Glu(260) and Glu(233) as the catalytic nucleophiles involved in the formation of the glycosyl-enzyme intermediate during catalysis by beta-Gal Xmn and beta-Gal-3 Bcir, respectively. These findings confirm the previous prediction of the position of these residues based on primary sequence similarities to other members of the glycoside hydrolase family 35.
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Affiliation(s)
- J E Blanchard
- Department of Chemistry, Protein Engineering Network of Centres of Excellence of Canada, University of British Columbia, Vancouver, BC, Canada V6T 1Z1
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