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Carrillo AK, Guiguemde WA, Guy RK. Evaluation of histone deacetylase inhibitors (HDACi) as therapeutic leads for human African trypanosomiasis (HAT). Bioorg Med Chem 2015; 23:5151-5. [DOI: 10.1016/j.bmc.2014.12.066] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 12/19/2014] [Accepted: 12/28/2014] [Indexed: 01/31/2023]
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Pettersson M, Bliman D, Jacobsson J, Nilsson JR, Min J, Iconaru L, Guy RK, Kriwacki RW, Andréasson J, Grøtli M. 8-Triazolylpurines: Towards Fluorescent Inhibitors of the MDM2/p53 Interaction. PLoS One 2015; 10:e0124423. [PMID: 25942498 PMCID: PMC4420247 DOI: 10.1371/journal.pone.0124423] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Accepted: 03/02/2015] [Indexed: 11/18/2022] Open
Abstract
Small molecule nonpeptidic mimics of α-helices are widely recognised as protein-protein interaction (PPIs) inhibitors. Protein-protein interactions mediate virtually all important regulatory pathways in a cell, and the ability to control and modulate PPIs is therefore of great significance to basic biology, where controlled disruption of protein networks is key to understanding network connectivity and function. We have designed and synthesised two series of 2,6,9-substituted 8-triazolylpurines as α-helix mimetics. The first series was designed based on low energy conformations but did not display any biological activity in a biochemical fluorescence polarisation assay targeting MDM2/p53. Although solution NMR conformation studies demonstrated that such molecules could mimic the topography of an α-helix, docking studies indicated that the same compounds were not optimal as inhibitors for the MDM2/p53 interaction. A new series of 8-triazolylpurines was designed based on a combination of docking studies and analysis of recently published inhibitors. The best compound displayed low micromolar inhibitory activity towards MDM2/p53 in a biochemical fluorescence polarisation assay. In order to evaluate the applicability of these compounds as biologically active and intrinsically fluorescent probes, their absorption/emission properties were measured. The compounds display fluorescent properties with quantum yields up to 50%.
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Paugh SW, Bonten EJ, Savic D, Ramsey LB, Thierfelder WE, Gurung P, Malireddi RKS, Actis M, Mayasundari A, Min J, Coss DR, Laudermilk LT, Panetta JC, McCorkle JR, Fan Y, Crews KR, Stocco G, Wilkinson MR, Ferreira AM, Cheng C, Yang W, Karol SE, Fernandez CA, Diouf B, Smith C, Hicks JK, Zanut A, Giordanengo A, Crona D, Bianchi JJ, Holmfeldt L, Mullighan CG, den Boer ML, Pieters R, Jeha S, Dunwell TL, Latif F, Bhojwani D, Carroll WL, Pui CH, Myers RM, Guy RK, Kanneganti TD, Relling MV, Evans WE. NALP3 inflammasome upregulation and CASP1 cleavage of the glucocorticoid receptor cause glucocorticoid resistance in leukemia cells. Nat Genet 2015; 47:607-14. [PMID: 25938942 PMCID: PMC4449308 DOI: 10.1038/ng.3283] [Citation(s) in RCA: 108] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 03/24/2015] [Indexed: 01/05/2023]
Abstract
Glucocorticoids are universally used in the treatment of acute lymphoblastic leukemia (ALL), and leukemia cell resistant to glucocorticoids confers a poor prognosis. To elucidate mechanisms of glucocorticoid resistance, we determined the sensitivity to prednisolone of primary leukemia cells from 444 newly diagnosed ALL patients, revealing significantly higher expression of caspase 1 (CASP1) and its activator NLRP3 in glucocorticoid resistant leukemia cells, due to significantly lower somatic methylation of CASP1 and NLRP3 promoters. Over-expression of CASP1 resulted in cleavage of the glucocorticoid receptor, diminished glucocorticoid-induced transcriptional response and increased glucocorticoid resistance. Knockdown or inhibition of CASP1 significantly increased glucocorticoid receptor levels and mitigated glucocorticoid resistance in CASP1 overexpressing ALL. Our findings establish a new mechanism by which the NLRP3/CASP1 inflammasome modulates cellular levels of the glucocorticoid receptor and diminishes cell sensitivity to glucocorticoids. The broad impact on glucocorticoid transcriptional response suggests this mechanism could also modify glucocorticoid effects in other diseases.
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Ortiz D, Guiguemde WA, Johnson A, Elya C, Anderson J, Clark J, Connelly M, Yang L, Min J, Sato Y, Guy RK, Landfear SM. Identification of Selective Inhibitors of the Plasmodium falciparum Hexose Transporter PfHT by Screening Focused Libraries of Anti-Malarial Compounds. PLoS One 2015; 10:e0123598. [PMID: 25894322 PMCID: PMC4404333 DOI: 10.1371/journal.pone.0123598] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Accepted: 02/20/2015] [Indexed: 12/04/2022] Open
Abstract
Development of resistance against current antimalarial drugs necessitates the search for novel drugs that interact with different targets and have distinct mechanisms of action. Malaria parasites depend upon high levels of glucose uptake followed by inefficient metabolic utilization via the glycolytic pathway, and the Plasmodium falciparum hexose transporter PfHT, which mediates uptake of glucose, has thus been recognized as a promising drug target. This transporter is highly divergent from mammalian hexose transporters, and it appears to be a permease that is essential for parasite viability in intra-erythrocytic, mosquito, and liver stages of the parasite life cycle. An assay was developed that is appropriate for high throughput screening against PfHT based upon heterologous expression of PfHT in Leishmania mexicana parasites that are null mutants for their endogenous hexose transporters. Screening of two focused libraries of antimalarial compounds identified two such compounds that are high potency selective inhibitors of PfHT compared to human GLUT1. Additionally, 7 other compounds were identified that are lower potency and lower specificity PfHT inhibitors but might nonetheless serve as starting points for identification of analogs with more selective properties. These results further support the potential of PfHT as a novel drug target.
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Min J, Attia RN, Arnold LA, Teske K, Connelly M, Lemieux G, Ashrafi K, Shelat A, Guy RK. Abstract 5389: Discovery of small molecule inhibitors of the interaction between PPARγ and SMRT. Cancer Res 2014. [DOI: 10.1158/1538-7445.am2014-5389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
The gamma isoform of the peroxisome proliferator-activated receptor (PPARγ) is a ligand-activated nuclear hormone receptor that plays central roles in regulating adipogenesis and maintaining lipid and glucose homeostasis. PPARγ is the molecular target for the thiazolidinedione (TZD) class of antidiabetic drugs. While clinically efficacious, the TZDs exhibit significant side effects that are mechanistically linked to PPARγ including weight gain, edema, and heart failure. SMRT (silencing mediator of retinoid acid and thyroid hormone receptor) and NCoR (nuclear receptor corepressor) are transcriptional corepressors that are critical for normal PPARγ function and act by repressing PPARγ-mediated transcriptional activity in the absence of agonist ligands. In order to explore an alternate method of activating PPARγ signaling, we designed a biochemical assay for the purpose of high-throughput screening (HTS) to identify inhibitors of the interaction between PPARγ and corepressors from our in-house library compounds (292K), which might act as pharmacological agonists. Herein, we report the use of this method to discover small molecule inhibitors of the corepressor interaction with PPARγ. Following hit validation and evaluation, we identified small molecule inhibitors acting through this novel mechanism that potently induce a cellular response similar to the known PPARγ agonist rosiglitazone. In addition, we also confirmed that our hit compound revealed induced adipogenesis in 3T3-L1 cell and reduced fat storage in C.elegans model. These findings highlight the potential of targeting the interaction of PPARγ and SMRT for the discovery of small molecule agonists of PPARγ.
Citation Format: Jaeki Min, Ramy Naguib Attia, Leggy A Arnold, Kelly Teske, Michele Connelly, George Lemieux, Kaveh Ashrafi, Anang Shelat, R. Kiplin Guy. Discovery of small molecule inhibitors of the interaction between PPARγ and SMRT. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5389. doi:10.1158/1538-7445.AM2014-5389
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Guiguemde WA, Hunt NH, Guo J, Marciano A, Haynes RK, Clark J, Guy RK, Golenser J. Treatment of murine cerebral malaria by artemisone in combination with conventional antimalarial drugs: antiplasmodial effects and immune responses. Antimicrob Agents Chemother 2014; 58:4745-54. [PMID: 24913162 PMCID: PMC4135990 DOI: 10.1128/aac.01553-13] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Accepted: 05/27/2014] [Indexed: 01/10/2023] Open
Abstract
The decreasing effectiveness of antimalarial therapy due to drug resistance necessitates constant efforts to develop new drugs. Artemisinin derivatives are the most recent drugs that have been introduced and are considered the first line of treatment, but there are already indications of Plasmodium falciparum resistance to artemisinins. Consequently, drug combinations are recommended for prevention of the induction of resistance. The research here demonstrates the effects of novel combinations of the new artemisinin derivative, artemisone, a recently described 10-alkylamino artemisinin derivative with improved antimalarial activity and reduced neurotoxicity. We here investigate its ability to kill P. falciparum in a high-throughput in vitro assay and to protect mice against lethal cerebral malaria caused by Plasmodium berghei ANKA when used alone or in combination with established antimalarial drugs. Artemisone effects against P. falciparum in vitro were synergistic with halofantrine and mefloquine, and additive with 25 other drugs, including chloroquine and doxycycline. The concentrations of artemisone combinations that were toxic against THP-1 cells in vitro were much higher than their effective antimalarial concentration. Artemisone, mefloquine, chloroquine, or piperaquine given individually mostly protected mice against cerebral malaria caused by P. berghei ANKA but did not prevent parasite recrudescence. Combinations of artemisone with any of the other three drugs did completely cure most mice of malaria. The combination of artemisone and chloroquine decreased the ratio of proinflammatory (gamma interferon, tumor necrosis factor) to anti-inflammatory (interleukin 10 [IL-10], IL-4) cytokines in the plasma of P. berghei-infected mice. Thus, artemisone in combinations with other antimalarial drugs might have a dual action, both killing parasites and limiting the potentially deleterious host inflammatory response.
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Vara BA, Mayasundari A, Tellis JC, Danneman MW, Arredondo V, Davis TA, Min J, Finch K, Guy RK, Johnston JN. Organocatalytic, diastereo- and enantioselective synthesis of nonsymmetric cis-stilbene diamines: a platform for the preparation of single-enantiomer cis-imidazolines for protein-protein inhibition. J Org Chem 2014; 79:6913-38. [PMID: 25017623 PMCID: PMC4120989 DOI: 10.1021/jo501003r] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
![]()
The
finding by scientists at Hoffmann-La Roche that cis-imidazolines could disrupt the protein–protein interaction
between p53 and MDM2, thereby inducing apoptosis in cancer cells,
raised considerable interest in this scaffold over the past decade.
Initial routes to these small molecules (i.e., Nutlin-3) provided
only the racemic form, with enantiomers being enriched by chromatographic
separation using high-pressure liquid chromatography (HPLC) and a
chiral stationary phase. Reported here is the first application of
an enantioselective aza-Henry approach to nonsymmetric cis-stilbene diamines and cis-imidazolines. Two novel
mono(amidine) organocatalysts (MAM) were discovered to provide high
levels of enantioselection (>95% ee) across a broad range of substrate
combinations. Furthermore, the versatility of the aza-Henry strategy
for preparing nonsymmetric cis-imidazolines is illustrated
by a comparison of the roles of aryl nitromethane and aryl aldimine
in the key step, which revealed unique substrate electronic effects
providing direction for aza-Henry substrate–catalyst matching.
This method was used to prepare highly substituted cis-4,5-diaryl imidazolines that project unique aromatic rings, and
these were evaluated for MDM2-p53 inhibition in a fluorescence polarization
assay. The diversification of access to cis-stilbene
diamine-derived imidazolines provided by this platform should streamline
their further development as chemical tools for disrupting protein–protein
interactions.
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Pritchard EM, Stewart E, Zhu F, Bradley C, Griffiths L, Yang L, Suryadevara PK, Zhang J, Freeman BB, Guy RK, Dyer MA. Pharmacokinetics and efficacy of the spleen tyrosine kinase inhibitor r406 after ocular delivery for retinoblastoma. Pharm Res 2014; 31:3060-72. [PMID: 24906597 PMCID: PMC4213378 DOI: 10.1007/s11095-014-1399-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Accepted: 04/28/2014] [Indexed: 12/14/2022]
Abstract
PURPOSE Retinoblastoma is a childhood cancer of the retina. Clinical trials have shown that local delivery of broad spectrum chemotherapeutic agents is efficacious. Recent studies characterizing the genomic and epigenomic landscape of retinoblastoma identified spleen tyrosine kinase (SYK) as a promising candidate for targeted therapy. The purpose of this study was to conduct preclinical testing of the SYK antagonist R406 to evaluate it as a candidate for retinoblastoma treatment. METHODS The efficacy of the SYK antagonist R406 delivered locally in a human orthotopic xenograft mouse model of retinoblastoma was tested. Intraocular exposure of R406 was determined for various routes and formulations. RESULTS There was no evidence of efficacy for subconjunctival. R406. Maximal vitreal concentration was 10-fold lower than the minimal concentration required to kill retinoblastoma cells in vitro. Dosage of R406 subconjunctivally from emulsion or suspension formulations, direct intravitreal injection of the soluble prodrug of R406 (R788), and repeated topical administration of R406 all increased vitreal exposure, but failed to reach the exposure required for retinoblastoma cell death in culture. CONCLUSION Taken together, these data suggest that R406 is not a viable clinical candidate for the treatment of retinoblastoma. This study highlights the importance of pharmacokinetic testing of molecular targeted retinoblastoma therapeutics.
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Yang J, Liang Q, Wang M, Jeffries C, Smithson D, Tu Y, Boulos N, Jacob MR, Shelat AA, Wu Y, Ravu RR, Gilbertson R, Avery MA, Khan IA, Walker LA, Guy RK, Li XC. UPLC-MS-ELSD-PDA as a powerful dereplication tool to facilitate compound identification from small-molecule natural product libraries. JOURNAL OF NATURAL PRODUCTS 2014; 77:902-9. [PMID: 24617915 PMCID: PMC4784093 DOI: 10.1021/np4009706] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The generation of natural product libraries containing column fractions, each with only a few small molecules, using a high-throughput, automated fractionation system, has made it possible to implement an improved dereplication strategy for selection and prioritization of leads in a natural product discovery program. Analysis of databased UPLC-MS-ELSD-PDA information of three leads from a biological screen employing the ependymoma cell line EphB2-EPD generated details on the possible structures of active compounds present. The procedure allows the rapid identification of known compounds and guides the isolation of unknown compounds of interest. Three previously known flavanone-type compounds, homoeriodictyol (1), hesperetin (2), and sterubin (3), were identified in a selected fraction derived from the leaves of Eriodictyon angustifolium. The lignan compound deoxypodophyllotoxin (8) was confirmed to be an active constituent in two lead fractions derived from the bark and leaves of Thuja occidentalis. In addition, two new but inactive labdane-type diterpenoids with an uncommon triol side chain were also identified as coexisting with deoxypodophyllotoxin in a lead fraction from the bark of T. occidentalis. Both diterpenoids were isolated in acetylated form, and their structures were determined as 14S,15-diacetoxy-13R-hydroxylabd-8(17)-en-19-oic acid (9) and 14R,15-diacetoxy-13S-hydroxylabd-8(17)-en-19-oic acid (10), respectively, by spectroscopic data interpretation and X-ray crystallography. This work demonstrates that a UPLC-MS-ELSD-PDA database produced during fractionation may be used as a powerful dereplication tool to facilitate compound identification from chromatographically tractable small-molecule natural product libraries.
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Lotharius J, Gamo-Benito FJ, Angulo-Barturen I, Clark J, Connelly M, Ferrer-Bazaga S, Parkinson T, Viswanath P, Bandodkar B, Rautela N, Bharath S, Duffy S, Avery VM, Möhrle JJ, Guy RK, Wells T. Repositioning: the fast track to new anti-malarial medicines? Malar J 2014; 13:143. [PMID: 24731288 PMCID: PMC4021201 DOI: 10.1186/1475-2875-13-143] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Accepted: 03/23/2014] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND Repositioning of existing drugs has been suggested as a fast track for developing new anti-malarial agents. The compound libraries of GlaxoSmithKline (GSK), Pfizer and AstraZeneca (AZ) comprising drugs that have undergone clinical studies in other therapeutic areas, but not achieved approval, and a set of US Food and Drug Administration (FDA)-approved drugs and other bio-actives were tested against Plasmodium falciparum blood stages. METHODS Molecules were tested initially against erythrocytic co-cultures of P. falciparum to measure proliferation inhibition using one of the following methods: SYBR®I dye DNA staining assay (3D7, K1 or NF54 strains); [(3)H] hypoxanthine radioisotope incorporation assay (3D7 and 3D7A strain); or 4',6-diamidino-2-phenylindole (DAPI) DNA imaging assay (3D7 and Dd2 strains). After review of the available clinical pharmacokinetic and safety data, selected compounds with low μM activity and a suitable clinical profile were tested in vivo either in a Plasmodium berghei four-day test or in the P. falciparum Pf3D7(0087/N9) huSCID 'humanized' mouse model. RESULTS Of the compounds included in the GSK and Pfizer sets, 3.8% (9/238) had relevant in vitro anti-malarial activity while 6/100 compounds from the AZ candidate drug library were active. In comparison, around 0.6% (24/3,800) of the FDA-approved drugs and other bio-actives were active. After evaluation of available clinical data, four investigational drugs, active in vitro were tested in the P. falciparum humanized mouse model: UK-112,214 (PAF-H1 inhibitor), CEP-701 (protein kinase inhibitor), CEP-1347 (protein kinase inhibitor), and PSC-833 (p-glycoprotein inhibitor). Only UK-112,214 showed significant efficacy against P. falciparum in vivo, although at high doses (ED90 131.3 mg/kg [95% CI 112.3, 156.7]), and parasitaemia was still present 96 hours after treatment commencement. Of the six actives from the AZ library, two compounds (AZ-1 and AZ-3) were marginally efficacious in vivo in a P. berghei model. CONCLUSIONS Repositioning of existing therapeutics in malaria is an attractive proposal. Compounds active in vitro at μM concentrations were identified. However, therapeutic concentrations may not be effectively achieved in mice or humans because of poor bio-availability and/or safety concerns. Stringent safety requirements for anti-malarial drugs, given their widespread use in children, make this a challenging area in which to reposition therapy.
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Morfouace M, Shelat A, Jacus M, Freeman BB, Turner D, Robinson S, Zindy F, Wang YD, Finkelstein D, Ayrault O, Bihannic L, Puget S, Li XN, Olson JM, Robinson GW, Guy RK, Stewart CF, Gajjar A, Roussel MF. Pemetrexed and gemcitabine as combination therapy for the treatment of Group3 medulloblastoma. Cancer Cell 2014; 25:516-29. [PMID: 24684846 PMCID: PMC3994669 DOI: 10.1016/j.ccr.2014.02.009] [Citation(s) in RCA: 106] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Revised: 10/29/2013] [Accepted: 02/18/2014] [Indexed: 01/05/2023]
Abstract
We devised a high-throughput, cell-based assay to identify compounds to treat Group3 medulloblastoma (G3 MB). Mouse G3 MBs neurospheres were screened against a library of approximately 7,000 compounds including US Food and Drug Administration-approved drugs. We found that pemetrexed and gemcitabine preferentially inhibited G3 MB proliferation in vitro compared to control neurospheres and substantially inhibited G3 MB proliferation in vivo. When combined, these two drugs significantly increased survival of mice bearing cortical implants of mouse and human G3 MBs that overexpress MYC compared to each agent alone, while having little effect on mouse MBs of the sonic hedgehog subgroup. Our findings strongly suggest that combination therapy with pemetrexed and gemcitabine is a promising treatment for G3 MBs.
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Wang C, Zhao Q, Min J, Muniyan S, Vargas M, Wang X, Dong Y, Guy RK, Lin MF, Keiser J, Vennerstrom JL. Antischistosomal versus antiandrogenic properties of aryl hydantoin Ro 13-3978. Am J Trop Med Hyg 2014; 90:1156-8. [PMID: 24686741 DOI: 10.4269/ajtmh.14-0029] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
In the early 1980s, the antischistosomal aryl hydantoin Ro 13-3978 (AH01), a close structural analogue of the androgen receptor antagonist nilutamide, was discovered. Administration of 100 mg/kg oral doses of AH01 to mice infected with adult and juvenile Schistosoma mansoni produced 95% and 64% total worm burden reductions, confirming its high activity against adult worms, and showing that AH01 is also effective against juvenile infections. AH01 had no measureable interaction with the androgen receptor in a ligand competition assay, but it did block dihydrotestosterone-induced cell proliferation in an androgen-dependent human prostate cancer cell line. For AH01, nilutamide, and three closely related aryl hydantoin derivatives, there was no correlation between antischistosomal activity and androgen receptor interaction.
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Guo K, Shelat AA, Guy RK, Kastan MB. Development of a cell-based, high-throughput screening assay for ATM kinase inhibitors. ACTA ACUST UNITED AC 2014; 19:538-46. [PMID: 24464432 DOI: 10.1177/1087057113520325] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The ATM (ataxia-telangiectasia, mutated) protein kinase is a major regulator of cellular responses to DNA double-strand breaks (DSBs), DNA lesions that can be caused by ionizing irradiation (IR), oxidative damage, or exposure to certain chemical agents. In response to DSBs, the ATM kinase is activated and subsequently phosphorylates numerous downstream substrates, including p53, Chk2, BRCA1, and KAP1, which affect processes such as cell cycle progression and DNA repair. Numerous studies have demonstrated that loss of ATM function results in enhanced sensitivity to ionizing irradiation in clinically relevant dose ranges, suggesting that ATM kinase is an attractive therapeutic target for enhancing tumor cell kill with radiotherapy. Previously identified small-molecule ATM kinase inhibitors, such as CP466722 and Ku55933, were identified using in vitro kinase assays carried out with recombinant ATM kinase isolated from mammalian cells. Since it has not been feasible to express full-length recombinant ATM in bacterial or baculovirus systems, a robust in vitro screening tool has been lacking. We have developed a cell-based assay that is robust, straightforward, and sensitive. Using this high-throughput assay, we screened more than 7000 compounds and discovered additional small molecules that inhibit the ATM kinase and further validated these hits by secondary assays.
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Hooft van Huijsduijnen R, Guy RK, Chibale K, Haynes RK, Peitz I, Kelter G, Phillips MA, Vennerstrom JL, Yuthavong Y, Wells TNC. Anticancer properties of distinct antimalarial drug classes. PLoS One 2013; 8:e82962. [PMID: 24391728 PMCID: PMC3877007 DOI: 10.1371/journal.pone.0082962] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Accepted: 10/22/2013] [Indexed: 12/31/2022] Open
Abstract
We have tested five distinct classes of established and experimental antimalarial drugs for their anticancer potential, using a panel of 91 human cancer lines. Three classes of drugs: artemisinins, synthetic peroxides and DHFR (dihydrofolate reductase) inhibitors effected potent inhibition of proliferation with IC50s in the nM- low µM range, whereas a DHODH (dihydroorotate dehydrogenase) and a putative kinase inhibitor displayed no activity. Furthermore, significant synergies were identified with erlotinib, imatinib, cisplatin, dasatinib and vincristine. Cluster analysis of the antimalarials based on their differential inhibition of the various cancer lines clearly segregated the synthetic peroxides OZ277 and OZ439 from the artemisinin cluster that included artesunate, dihydroartemisinin and artemisone, and from the DHFR inhibitors pyrimethamine and P218 (a parasite DHFR inhibitor), emphasizing their shared mode of action. In order to further understand the basis of the selectivity of these compounds against different cancers, microarray-based gene expression data for 85 of the used cell lines were generated. For each compound, distinct sets of genes were identified whose expression significantly correlated with compound sensitivity. Several of the antimalarials tested in this study have well-established and excellent safety profiles with a plasma exposure, when conservatively used in malaria, that is well above the IC50s that we identified in this study. Given their unique mode of action and potential for unique synergies with established anticancer drugs, our results provide a strong basis to further explore the potential application of these compounds in cancer in pre-clinical or and clinical settings.
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Nilsen A, LaCrue AN, White KL, Forquer IP, Cross RM, Marfurt J, Mather MW, Delves MJ, Shackleford DM, Saenz FE, Morrisey JM, Steuten J, Mutka T, Li Y, Wirjanata G, Ryan E, Duffy S, Kelly JX, Sebayang BF, Zeeman AM, Noviyanti R, Sinden RE, Kocken CHM, Price RN, Avery VM, Angulo-Barturen I, Jiménez-Díaz MB, Ferrer S, Herreros E, Sanz LM, Gamo FJ, Bathurst I, Burrows JN, Siegl P, Guy RK, Winter RW, Vaidya AB, Charman SA, Kyle DE, Manetsch R, Riscoe MK. Quinolone-3-diarylethers: a new class of antimalarial drug. Sci Transl Med 2013; 5:177ra37. [PMID: 23515079 DOI: 10.1126/scitranslmed.3005029] [Citation(s) in RCA: 164] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The goal for developing new antimalarial drugs is to find a molecule that can target multiple stages of the parasite's life cycle, thus impacting prevention, treatment, and transmission of the disease. The 4(1H)-quinolone-3-diarylethers are selective potent inhibitors of the parasite's mitochondrial cytochrome bc1 complex. These compounds are highly active against the human malaria parasites Plasmodium falciparum and Plasmodium vivax. They target both the liver and blood stages of the parasite as well as the forms that are crucial for disease transmission, that is, the gametocytes, the zygote, the ookinete, and the oocyst. Selected as a preclinical candidate, ELQ-300 has good oral bioavailability at efficacious doses in mice, is metabolically stable, and is highly active in blocking transmission in rodent models of malaria. Given its predicted low dose in patients and its predicted long half-life, ELQ-300 has potential as a new drug for the treatment, prevention, and, ultimately, eradication of human malaria.
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Singh H, Shelat AA, Singh A, Boulos N, Williams RT, Guy RK. A screening-based approach to circumvent tumor microenvironment-driven intrinsic resistance to BCR-ABL+ inhibitors in Ph+ acute lymphoblastic leukemia. ACTA ACUST UNITED AC 2013; 19:158-67. [PMID: 23989453 DOI: 10.1177/1087057113501081] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Signaling by the BCR-ABL fusion kinase drives Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) and chronic myelogenous leukemia (CML). Despite their clinical activity in many patients with CML, the BCR-ABL kinase inhibitors (BCR-ABL-KIs) imatinib, dasatinib, and nilotinib provide only transient leukemia reduction in patients with Ph+ ALL. While host-derived growth factors in the leukemia microenvironment have been invoked to explain this drug resistance, their relative contribution remains uncertain. Using genetically defined murine Ph+ ALL cells, we identified interleukin 7 (IL-7) as the dominant host factor that attenuates response to BCR-ABL-KIs. To identify potential combination drugs that could overcome this IL-7-dependent BCR-ABL-KI-resistant phenotype, we screened a small-molecule library including Food and Drug Administration-approved drugs. Among the validated hits, the well-tolerated antimalarial drug dihydroartemisinin (DHA) displayed potent activity in vitro and modest in vivo monotherapy activity against engineered murine BCR-ABL-KI-resistant Ph+ ALL. Strikingly, cotreatment with DHA and dasatinib in vivo strongly reduced primary leukemia burden and improved long-term survival in a murine model that faithfully captures the BCR-ABL-KI-resistant phenotype of human Ph+ ALL. This cotreatment protocol durably cured 90% of treated animals, suggesting that this cell-based screening approach efficiently identified drugs that could be rapidly moved to human clinical testing.
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Hwang JY, Smithson DC, Holbrook G, Zhu F, Connelly MC, Kaiser M, Brun R, Kiplin Guy R. Optimization of the electrophile of chloronitrobenzamide leads active against Trypanosoma brucei. Bioorg Med Chem Lett 2013; 23:4127-31. [PMID: 23746473 DOI: 10.1016/j.bmcl.2013.05.049] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Revised: 05/09/2013] [Accepted: 05/13/2013] [Indexed: 01/08/2023]
Abstract
We previously reported the phenylchloronitrobenzamides (PCNBs), a novel class of compounds active against the species of trypanosomes that cause Human African Trypanosomiasis (HAT). Herein, we explored the potential to adjust the reactivity of the electrophilic chloronitrobenzamide core. These studies identified compound 7d that potently inhibited the growth of trypanosomes (EC50=120nM for Trypanosoma b. brucei, 18nM for Trypanosoma b. rhodesiense, and 38nM for Trypanosoma b. gambiense) without significant cytotoxicity against mammalian cell lines (EC50>25μM for HepG2, HEK293, Raji, and BJ cell lines) and also had good stability in microsomal models (t1/2>4h in both human and mouse). Overall these properties indicate the compound 7d and its analogs are worth further exploration as potential leads for HAT.
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69
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Hwang JY, Smithson D, Zhu F, Holbrook G, Connelly MC, Kaiser M, Brun R, Guy RK. Optimization of chloronitrobenzamides (CNBs) as therapeutic leads for human African trypanosomiasis (HAT). J Med Chem 2013; 56:2850-60. [PMID: 23484493 DOI: 10.1021/jm301687p] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We previously reported the discovery of the activity of chloronitrobenzamides (CNBs) against bloodstream forms of Trypanosoma brucei . Herein we disclose extensive structure-activity relationship and structure-property relationship studies aimed at identification of tractable early leads for clinical development. These studies revealed a promising lead compound, 17b, that exhibited nanomolar potency against T. brucei (EC50 = 27 nM for T. b. brucei, 7 nM for T. b. rhodesiense, and 2 nM for T. b. gambiense ) with excellent selectivity for parasite cells relative to mammalian cell lines (EC50 > 25 μM). In addition compound 17b displayed suitable physiochemical characteristics and microsomal stability (t1/2 > 4 h for human and mouse) to justify pursuing in vivo studies.
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70
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Hwang JY, Attia RR, Carrillo AK, Connelly MC, Guy RK. Synthesis and evaluation of methylsulfonylnitrobenzamides (MSNBAs) as inhibitors of the thyroid hormone receptor-coactivator interaction. Bioorg Med Chem Lett 2013; 23:1891-5. [PMID: 23414840 PMCID: PMC3594046 DOI: 10.1016/j.bmcl.2012.12.055] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2012] [Revised: 12/13/2012] [Accepted: 12/17/2012] [Indexed: 12/01/2022]
Abstract
We previously identified the methylsulfonylnitrobenzoates (MSNBs) that block the interaction of the thyroid hormone receptor with its obligate transcriptional coactivators and prevent thyroid hormone signaling. As part of our lead optimization work we demonstrated that sulfonylnitrophenylthiazoles (SNPTs), which replace the ester linkage of MSNBs with a thiazole, also inhibited coactivator binding to TR. Here we report that replacement of the ester with an amide (methylsulfonylnitrobenzamides, MSNBA) also provides active TR antagonists.
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71
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Cloete TT, Krebs HJ, Clark JA, Connelly MC, Orcutt A, Sigal MS, Kiplin Guy R, N’Da DD. Antimalarial activity of 10-alkyl/aryl esters and -aminoethylethers of artemisinin. Bioorg Chem 2013; 46:10-6. [DOI: 10.1016/j.bioorg.2012.10.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2012] [Revised: 09/19/2012] [Accepted: 10/04/2012] [Indexed: 11/17/2022]
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72
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Zhang L, Fourches D, Sedykh A, Zhu H, Golbraikh A, Ekins S, Clark J, Connelly MC, Sigal M, Hodges D, Guiguemde A, Guy RK, Tropsha A. Discovery of novel antimalarial compounds enabled by QSAR-based virtual screening. J Chem Inf Model 2013; 53:475-92. [PMID: 23252936 DOI: 10.1021/ci300421n] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Quantitative structure-activity relationship (QSAR) models have been developed for a data set of 3133 compounds defined as either active or inactive against P. falciparum. Because the data set was strongly biased toward inactive compounds, different sampling approaches were employed to balance the ratio of actives versus inactives, and models were rigorously validated using both internal and external validation approaches. The balanced accuracy for assessing the antimalarial activities of 70 external compounds was between 87% and 100% depending on the approach used to balance the data set. Virtual screening of the ChemBridge database using QSAR models identified 176 putative antimalarial compounds that were submitted for experimental validation, along with 42 putative inactives as negative controls. Twenty five (14.2%) computational hits were found to have antimalarial activities with minimal cytotoxicity to mammalian cells, while all 42 putative inactives were confirmed experimentally. Structural inspection of confirmed active hits revealed novel chemical scaffolds, which could be employed as starting points to discover novel antimalarial agents.
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73
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Lowes D, Pradhan A, Iyer LV, Parman T, Gow J, Zhu F, Furimsky A, Lemoff A, Guiguemde WA, Sigal M, Clark JA, Wilson E, Tang L, Connelly MC, Derisi JL, Kyle DE, Mirsalis J, Guy RK. Lead optimization of antimalarial propafenone analogues. J Med Chem 2012; 55:6087-93. [PMID: 22708838 DOI: 10.1021/jm300286a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Previously reported studies identified analogues of propafenone that had potent antimalarial activity, reduced cardiac ion channel activity, and properties that suggested the potential for clinical development for malaria. Careful examination of the bioavailability, pharmacokinetics, toxicology, and efficacy of this series of compounds using rodent models revealed orally bioavailable compounds that are nontoxic and suppress parasitemia in vivo. Although these compounds possess potential for further preclinical development, they also carry some significant challenges.
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Bista M, Smithson D, Pecak A, Salinas G, Pustelny K, Min J, Pirog A, Finch K, Zdzalik M, Waddell B, Wladyka B, Kedracka-Krok S, Dyer MA, Dubin G, Guy RK. On the mechanism of action of SJ-172550 in inhibiting the interaction of MDM4 and p53. PLoS One 2012; 7:e37518. [PMID: 22675482 PMCID: PMC3366986 DOI: 10.1371/journal.pone.0037518] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2012] [Accepted: 04/20/2012] [Indexed: 12/22/2022] Open
Abstract
SJ-172550 (1) was previously discovered in a biochemical high throughput screen for inhibitors of the interaction of MDMX and p53 and characterized as a reversible inhibitor (J. Biol. Chem. 2010; 285∶10786). Further study of the biochemical mode of action of 1 has shown that it acts through a complicated mechanism in which the compound forms a covalent but reversible complex with MDMX and locks MDMX into a conformation that is unable to bind p53. The relative stability of this complex is influenced by many factors including the reducing potential of the media, the presence of aggregates, and other factors that influence the conformational stability of the protein. This complex mechanism of action hinders the further development of compound 1 as a selective MDMX inhibitor.
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Guiguemde WA, Shelat AA, Garcia-Bustos JF, Diagana TT, Gamo FJ, Guy RK. Global phenotypic screening for antimalarials. ACTA ACUST UNITED AC 2012; 19:116-29. [PMID: 22284359 DOI: 10.1016/j.chembiol.2012.01.004] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Revised: 01/10/2012] [Accepted: 01/10/2012] [Indexed: 12/20/2022]
Abstract
Malaria, a devastating infectious disease caused by Plasmodium spp., leads to roughly 655,000 deaths per year, mostly of African children. To compound the problem, drug resistance has emerged to all classical antimalarials and may be emerging for artemisinin-based combination therapies. To address the need for new antimalarials with novel mechanisms, several groups carried out phenotypic screening campaigns to identify compounds inhibiting growth of the blood stages of Plasmodium falciparum. In this review, we describe the characterization of these compounds, explore currently ongoing strategies to develop lead molecules, and endorse the concept of a "malaria box" of publicly accessible active compounds.
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