Discovery of Potent and Selective Inhibitors for ADAMTS-4 through DNA-Encoded Library Technology (ELT).

Science.gov (United States)

Ding, Yun; O'Keefe, Heather; DeLorey, Jennifer L; Israel, David I; Messer, Jeffrey A; Chiu, Cynthia H; Skinner, Steven R; Matico, Rosalie E; Murray-Thompson, Monique F; Li, Fan; Clark, Matthew A; Cuozzo, John W; Arico-Muendel, Christopher; Morgan, Barry A

2015-08-13

The aggrecan degrading metalloprotease ADAMTS-4 has been identified as a novel therapeutic target for osteoarthritis. Here, we use DNA-encoded Library Technology (ELT) to identify novel ADAMTS-4 inhibitors from a DNA-encoded triazine library by affinity selection. Structure-activity relationship studies based on the selection information led to the identification of potent and highly selective inhibitors. For example, 4-(((4-(6,7-dimethoxy-3,4-dihydroisoquinolin-2(1H)-yl)-6-(((4-methylpiperazin-1-yl)methyl)amino)-1,3,5-triazin-2-yl)amino)methyl)-N-ethyl-N-(m-tolyl)benzamide has IC50 of 10 nM against ADAMTS-4, with >1000-fold selectivity over ADAMT-5, MMP-13, TACE, and ADAMTS-13. These inhibitors have no obvious zinc ligand functionality.

Developing selective histone deacetylases (HDACs inhibitors through ebselen and analogs

Directory of Open Access Journals (Sweden)

Wang Y

2017-05-01

Full Text Available Yuren Wang,1 Jason Wallach,2 Stephanie Duane,1 Yuan Wang,1 Jianghong Wu,1 Jeffrey Wang,1 Adeboye Adejare,2 Haiching Ma1 1Reaction Biology Corp., Malvern, 2Department of Pharmaceutical Sciences, Philadelphia College of Pharmacy, University of the Sciences, Philadelphia, PA, USA Abstract: Histone deacetylases (HDACs are key regulators of gene expression in cells and have been investigated as important therapeutic targets for cancer and other diseases. Different subtypes of HDACs appear to play disparate roles in the cells and are associated with specific diseases. Therefore, substantial effort has been made to develop subtype-selective HDAC inhibitors. In an effort to discover existing scaffolds with HDAC inhibitory activity, we screened a drug library approved by the US Food and Drug Administration and a National Institutes of Health Clinical Collection compound library in HDAC enzymatic assays. Ebselen, a clinical safe compound, was identified as a weak inhibitor of several HDACs, including HDAC1, HDAC3, HDAC4, HDAC5, HDAC6, HDAC7, HDAC8, and HDAC9 with half maximal inhibitory concentrations approximately single digit of µM. Two ebselen analogs, ebselen oxide and ebsulfur (a diselenide analog of ebselen, also inhibited these HDACs, however with improved potencies on HDAC8. Benzisothiazol, the core structure of ebsulfur, specifically inhibited HDAC6 at a single digit of µM but had no inhibition on other HDACs. Further efforts on structure–activity relationship based on the core structure of ebsulfur led to the discovery of a novel class of potent and selective HDAC6 inhibitors with RBC-2008 as the lead compound with single-digit nM potency. This class of histone deacetylase inhibitor features a novel pharmacophore with an ebsulfur scaffold selectively targeting HDAC6. Consistent with its inhibition on HDAC6, RBC-2008 significantly increased the acetylation levels of α-tubulin in PC-3 cells. Furthermore, treatment with these compounds led to

Design, Synthesis and Biological Evaluation of Histone Deacetylase (HDAC) Inhibitors: Saha (Vorinostat) Analogs and Biaryl Indolyl Benzamide Inhibitors Display Isoform Selectivity

Science.gov (United States)

Negmeldin, Ahmed Thabet

HDAC proteins have emerged as interesting targets for anti-cancer drugs due to their involvement in cancers, as well as several other diseases. Several HDAC inhibitors have been approved by the FDA as anti-cancer drugs, including SAHA (suberoylanilide hydroxamic acid, Vorinostat). Unfortunately, SAHA inhibits most HDAC isoforms, which limit its use as a pharmacological tool and may lead to side effects in the clinic. In this work we were interested in developing isoform selective HDAC inhibitors, which may decrease or eliminate the side effects associated with non-selective inhibitors treatment. In addition, isoform selective HDAC inhibitors can be used as biological tools to help understand the HDAC-related cancer biology. Our strategy was based on synthesis and screening of several derivatives of the non-selective FDA approved drug SAHA substituted at different positions of the linker region. Several SAHA analogs modified at the C4 and C5 positions of the linker were synthesized. The new C4- and C5-modified SAHA libraries, along with the previously synthesized C2-modified SAHA analogs were screened in vitro and in cellulo for HDAC isoform selectivity. Interestingly, several analogs exhibited dual HDAC6/HDAC8 selectivity. Enantioselective syntheses of the pure enantiomers of some of the interesting analogs were performed and the enantiomers were screened in vitro. Among the most interesting analogs, ( R)-C4-benzyl SAHA displayed 520- to 1300-fold selectivity for HDAC6 and HDAC8 over HDAC1, 2, and 3, with IC50 values of 48 and 27 nM with HDAC6 and 8, respectively. Docking studies were performed to provide structural rationale for the observed selectivity of the new analogs. In addition, rational design, synthesis, and screening of several other biaryl indolyl benzamide HDAC inhibitors is discussed, and some showed modest HDAC1 selectivity. The new biaryl indolyl benzamides can be useful to further develop HDAC1 selective inhibitors. The dual HDAC6/8 selective

Molecular Mechanism of Selectivity among G Protein-Coupled Receptor Kinase 2 Inhibitors

Energy Technology Data Exchange (ETDEWEB)

Thal, David M.; Yeow, Raymond Y.; Schoenau, Christian; Huber, Jochen; Tesmer, John J.G. (Sanofi); (Michigan)

2012-07-11

G protein-coupled receptors (GPCRs) are key regulators of cell physiology and control processes ranging from glucose homeostasis to contractility of the heart. A major mechanism for the desensitization of activated GPCRs is their phosphorylation by GPCR kinases (GRKs). Overexpression of GRK2 is strongly linked to heart failure, and GRK2 has long been considered a pharmaceutical target for the treatment of cardiovascular disease. Several lead compounds developed by Takeda Pharmaceuticals show high selectivity for GRK2 and therapeutic potential for the treatment of heart failure. To understand how these drugs achieve their selectivity, we determined crystal structures of the bovine GRK2-G{beta}{gamma} complex in the presence of two of these inhibitors. Comparison with the apoGRK2-G{beta}{gamma} structure demonstrates that the compounds bind in the kinase active site in a manner similar to that of the AGC kinase inhibitor balanol. Both balanol and the Takeda compounds induce a slight closure of the kinase domain, the degree of which correlates with the potencies of the inhibitors. Based on our crystal structures and homology modeling, we identified five amino acids surrounding the inhibitor binding site that we hypothesized could contribute to inhibitor selectivity. However, our results indicate that these residues are not major determinants of selectivity among GRK subfamilies. Rather, selectivity is achieved by the stabilization of a unique inactive conformation of the GRK2 kinase domain.

Identification and Structure-Function Analysis of Subfamily Selective G Protein-Coupled Receptor Kinase Inhibitors

Energy Technology Data Exchange (ETDEWEB)

Homan, Kristoff T.; Larimore, Kelly M.; Elkins, Jonathan M.; Szklarz, Marta; Knapp, Stefan; Tesmer, John J.G. [Michigan; (Oxford)

2015-02-13

Selective inhibitors of individual subfamilies of G protein-coupled receptor kinases (GRKs) would serve as useful chemical probes as well as leads for therapeutic applications ranging from heart failure to Parkinson’s disease. To identify such inhibitors, differential scanning fluorimetry was used to screen a collection of known protein kinase inhibitors that could increase the melting points of the two most ubiquitously expressed GRKs: GRK2 and GRK5. Enzymatic assays on 14 of the most stabilizing hits revealed that three exhibit nanomolar potency of inhibition for individual GRKs, some of which exhibiting orders of magnitude selectivity. Most of the identified compounds can be clustered into two chemical classes: indazole/dihydropyrimidine-containing compounds that are selective for GRK2 and pyrrolopyrimidine-containing compounds that potently inhibit GRK1 and GRK5 but with more modest selectivity. The two most potent inhibitors representing each class, GSK180736A and GSK2163632A, were cocrystallized with GRK2 and GRK1, and their atomic structures were determined to 2.6 and 1.85 Å spacings, respectively. GSK180736A, developed as a Rho-associated, coiled-coil-containing protein kinase inhibitor, binds to GRK2 in a manner analogous to that of paroxetine, whereas GSK2163632A, developed as an insulin-like growth factor 1 receptor inhibitor, occupies a novel region of the GRK active site cleft that could likely be exploited to achieve more selectivity. However, neither compound inhibits GRKs more potently than their initial targets. This data provides the foundation for future efforts to rationally design even more potent and selective GRK inhibitors.

Adaptive evolution and elucidating the potential inhibitor against schizophrenia to target DAOA (G72) isoforms.

Science.gov (United States)

Sehgal, Sheikh Arslan; Mannan, Shazia; Kanwal, Sumaira; Naveed, Ishrat; Mir, Asif

2015-01-01

Schizophrenia (SZ), a chronic mental and heritable disorder characterized by neurophysiological impairment and neuropsychological abnormalities, is strongly associated with D-amino acid oxidase activator (DAOA, G72). Research studies emphasized that overexpression of DAOA may be responsible for improper functioning of neurotransmitters, resulting in neurological disorders like SZ. In the present study, a hybrid approach of comparative modeling and molecular docking followed by inhibitor identification and structure modeling was employed. Screening was performed by two-dimensional similarity search against selected inhibitor, keeping in view the physiochemical properties of the inhibitor. Here, we report an inhibitor compound which showed maximum binding affinity against four selected isoforms of DAOA. Docking studies revealed that Glu-53, Thr-54, Lys-58, Val-85, Ser-86, Tyr-87, Leu-88, Glu-90, Leu-95, Val-98, Ser-100, Glu-112, Tyr-116, Lys-120, Asp-121, and Arg-122 are critical residues for receptor-ligand interaction. The C-terminal of selected isoforms is conserved, and binding was observed on the conserved region of isoforms. We propose that selected inhibitor might be more potent on the basis of binding energy values. Further analysis of this inhibitor through site-directed mutagenesis could be helpful for exploring the details of ligand-binding pockets. Overall, the findings of this study may be helpful in designing novel therapeutic targets to cure SZ.

Promiscuity and selectivity of small-molecule inhibitors across TAM receptor tyrosine kinases in pediatric leukemia.

Science.gov (United States)

Liu, Mao-Hua; Chen, Shi-Bing; Yu, Juan; Liu, Cheng-Jun; Zhang, Xiao-Jing

2017-08-01

The TAM receptor tyrosine kinase family member Mer has been recognized as an attractive therapeutic target for pediatric leukemia. Beside Mer the family contains other two kinases, namely, Tyro3 and Axl, which are highly homologues with Mer and thus most existing small-molecule inhibitors show moderate or high promiscuity across the three kinases. Here, the structural basis and energetic property of selective binding of small-molecule inhibitors to the three kinases were investigated at molecular level. It is found that the selectivity is primarily determined by the size, shape and configuration of kinase's ATP-binding site; the Mer and Axl possess a small, closed active pocket as compared to the bulky, open pocket of Tyro3. The location and conformation of active-site residues of Mer and Axl are highly consistent, suggesting that small-molecule inhibitors generally have a low Mer-over-Axl selectivity and a high Mer-over-Tyro3 selectivity. We demonstrated that the difference in ATP binding potency to the three kinases is also responsible for inhibitor selectivity. We also found that the long-range interactions and allosteric effect arising from rest of the kinase's active site can indirectly influence inhibitor binding and selectivity. Copyright © 2017 Elsevier Inc. All rights reserved.

Cysteine Protease Inhibitors as Chemotherapy: Lessons from a Parasite Target

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Selzer, Paul M.; Pingel, Sabine; Hsieh, Ivy; Ugele, Bernhard; Chan, Victor J.; Engel, Juan C.; Bogyo, Matthew; Russell, David G.; Sakanari, Judy A.; McKerrow, James H.

1999-09-01

Papain family cysteine proteases are key factors in the pathogenesis of cancer invasion, arthritis, osteoporosis, and microbial infections. Targeting this enzyme family is therefore one strategy in the development of new chemotherapy for a number of diseases. Little is known, however, about the efficacy, selectivity, and safety of cysteine protease inhibitors in cell culture or in vivo. We now report that specific cysteine protease inhibitors kill Leishmania parasites in vitro, at concentrations that do not overtly affect mammalian host cells. Inhibition of Leishmania cysteine protease activity was accompanied by defects in the parasite's lysosome/endosome compartment resembling those seen in lysosomal storage diseases. Colocalization of anti-protease antibodies with biotinylated surface proteins and accumulation of undigested debris and protease in the flagellar pocket of treated parasites were consistent with a pathway of protease trafficking from flagellar pocket to the lysosome/endosome compartment. The inhibitors were sufficiently absorbed and stable in vivo to ameliorate the pathology associated with a mouse model of Leishmania infection.

Hydroxybenzoic Acid Derivatives as Dual-Target Ligands: Mitochondriotropic Antioxidants and Cholinesterase Inhibitors.

Science.gov (United States)

Oliveira, Catarina; Cagide, Fernando; Teixeira, José; Amorim, Ricardo; Sequeira, Lisa; Mesiti, Francesco; Silva, Tiago; Garrido, Jorge; Remião, Fernando; Vilar, Santiago; Uriarte, Eugenio; Oliveira, Paulo J; Borges, Fernanda

2018-01-01

Alzheimer's disease (AD) is a multifactorial age-related disease associated with oxidative stress (OS) and impaired cholinergic transmission. Accordingly, targeting mitochondrial OS and restoring cholinergic transmission can be an effective therapeutic strategy toward AD. Herein, we report for the first time dual-target hydroxybenzoic acid (HBAc) derivatives acting as mitochondriotropic antioxidants and cholinesterase (ChE) inhibitors. The studies were performed with two mitochondriotropic antioxidants AntiOxBEN 1 (catechol derivative), and AntiOxBEN 2 (pyrogallol derivative) and compounds 15-18 , which have longer spacers. Compounds AntiOxBEN 1 and 15 , with a shorter carbon chain spacer (six- and eight-carbon) were shown to be potent antioxidants and BChE inhibitors (IC 50 = 85 ± 5 and 106 ± 5 nM, respectively), while compounds 17 and 18 with a 10-carbon chain were more effective AChE inhibitors (IC 50 = 7.7 ± 0.4 and 7.2 ± 0.5 μM, respectively). Interestingly, molecular modeling data pointed toward bifunctional ChEs inhibitors. The most promising ChE inhibitors acted by a non-competitive mechanism. In general, with exception of compounds 15 and 17 , no cytotoxic effects were observed in differentiated human neuroblastoma (SH-SY5Y) and human hepatocarcinoma (HepG2) cells, while Aβ-induced cytotoxicity was significantly prevented by the new dual-target HBAc derivatives. Overall, due to its BChE selectivity, favorable toxicological profile, neuroprotective activity and drug-like properties, which suggested blood-brain barrier (BBB) permeability, the mitochondriotropic antioxidant AntiOxBEN 1 is considered a valid lead candidate for the development of dual acting drugs for AD and other mitochondrial OS-related diseases.

Hydroxybenzoic Acid Derivatives as Dual-Target Ligands: Mitochondriotropic Antioxidants and Cholinesterase Inhibitors

Directory of Open Access Journals (Sweden)

Catarina Oliveira

2018-04-01

Full Text Available Alzheimer's disease (AD is a multifactorial age-related disease associated with oxidative stress (OS and impaired cholinergic transmission. Accordingly, targeting mitochondrial OS and restoring cholinergic transmission can be an effective therapeutic strategy toward AD. Herein, we report for the first time dual-target hydroxybenzoic acid (HBAc derivatives acting as mitochondriotropic antioxidants and cholinesterase (ChE inhibitors. The studies were performed with two mitochondriotropic antioxidants AntiOxBEN1 (catechol derivative, and AntiOxBEN2 (pyrogallol derivative and compounds 15–18, which have longer spacers. Compounds AntiOxBEN1 and 15, with a shorter carbon chain spacer (six- and eight-carbon were shown to be potent antioxidants and BChE inhibitors (IC50 = 85 ± 5 and 106 ± 5 nM, respectively, while compounds 17 and 18 with a 10-carbon chain were more effective AChE inhibitors (IC50 = 7.7 ± 0.4 and 7.2 ± 0.5 μM, respectively. Interestingly, molecular modeling data pointed toward bifunctional ChEs inhibitors. The most promising ChE inhibitors acted by a non-competitive mechanism. In general, with exception of compounds 15 and 17, no cytotoxic effects were observed in differentiated human neuroblastoma (SH-SY5Y and human hepatocarcinoma (HepG2 cells, while Aβ-induced cytotoxicity was significantly prevented by the new dual-target HBAc derivatives. Overall, due to its BChE selectivity, favorable toxicological profile, neuroprotective activity and drug-like properties, which suggested blood-brain barrier (BBB permeability, the mitochondriotropic antioxidant AntiOxBEN1 is considered a valid lead candidate for the development of dual acting drugs for AD and other mitochondrial OS-related diseases.

Hydroxybenzoic acid derivatives as dual-target ligands: mitochondriotropic antioxidants and cholinesterase inhibitors

Science.gov (United States)

Oliveira, Catarina; Cagide, Fernando; Teixeira, José; Amorim, Ricardo; Sequeira, Lisa; Mesiti, Francesco; Silva, Tiago; Garrido, Jorge; Remião, Fernando; Vilar, Santiago; Uriarte, Eugenio; Oliveira, Paulo J.; Borges, Fernanda

2018-04-01

Alzheimer’s disease (AD) is a multifactorial age-related disease associated with oxidative stress (OS) and impaired cholinergic transmission. Accordingly, targeting mitochondrial OS and restoring cholinergic transmission can be an effective therapeutic strategy towards AD. Herein, we report for the first time dual-target hydroxybenzoic acid (HBAc) derivatives acting as mitochondriotropic antioxidants and cholinesterase (ChE) inhibitors. The studies were performed with two mitochondriotropic antioxidants AntiOxBEN1 (catechol derivative), and AntiOxBEN2 (pyrogallol derivative) and compounds 15-18, which have longer spacers. Compounds AntiOxBEN1 and 15, with a shorter carbon chain spacer (six- and eight-carbon) were shown to be potent antioxidants and BChE inhibitors (IC50 = 85 ± 5 and 106 ± 5 nM, respectively), while compounds 17 and 18 with a ten-carbon chain were more effective AChE inhibitors (IC50 = 7.7 ± 0.4 and 7.2 ± 0.5 nM, respectively). Interestingly, molecular modelling data pointed towards bifunctional ChEs inhibitors. The most promising ChE inhibitors acted by a non-competitive mechanism. In general, with exception of compounds 15 and 17, no cytotoxic effects were observed in differentiated human neuroblastoma (SH-SY5Y) and human hepatocarcinoma (HepG2) cells, while Αβ-induced cytotoxicity was significantly prevented by the new dual-target HBAc derivatives. Overall, due to its BChE selectivity, favourable toxicological profile, neuroprotective activity and drug-like properties, which suggested blood-brain barrier (BBB) permeability, the mitochondriotropic antioxidant AntiOxBEN1 is considered a valid lead candidate for the development of dual acting drugs for AD and other mitochondrial OS-related disease

Design and optimization of a series of 1-sulfonylpyrazolo[4,3-b]pyridines as selective c-Met inhibitors.

Science.gov (United States)

Ma, Yuchi; Sun, Guangqiang; Chen, Danqi; Peng, Xia; Chen, Yue-Lei; Su, Yi; Ji, Yinchun; Liang, Jin; Wang, Xin; Chen, Lin; Ding, Jian; Xiong, Bing; Ai, Jing; Geng, Meiyu; Shen, Jingkang

2015-03-12

c-Met has emerged as an attractive target for targeted cancer therapy because of its abnormal activation in many cancer cells. To identify high potent and selective c-Met inhibitors, we started with profiling the potency and in vitro metabolic stability of a reported hit 7. By rational design, a novel sulfonylpyrazolo[4,3-b]pyridine 9 with improved DMPK properties was discovered. Further elaboration of π-π stacking interactions and solvent accessible polar moieties led to a series of highly potent and selective type I c-Met inhibitors. On the basis of in vitro and in vivo pharmacological and pharmacokinetics studies, compound 46 was selected as a preclinical candidate for further anticancer drug development.

Elaboration of a fragment library hit produces potent and selective aspartate semialdehyde dehydrogenase inhibitors.

Science.gov (United States)

Thangavelu, Bharani; Bhansali, Pravin; Viola, Ronald E

2015-10-15

Aspartate-β-semialdehyde dehydrogenase (ASADH) lies at the first branch point in the aspartate metabolic pathway which leads to the biosynthesis of several essential amino acids and some important metabolites. This pathway is crucial for many metabolic processes in plants and microbes like bacteria and fungi, but is absent in mammals. Therefore, the key microbial enzymes involved in this pathway are attractive potential targets for development of new antibiotics with novel modes of action. The ASADH enzyme family shares the same substrate binding and active site catalytic groups; however, the enzymes from representative bacterial and fungal species show different inhibition patterns when previously screened against low molecular weight inhibitors identified from fragment library screening. In the present study several approaches, including fragment based drug discovery (FBDD), inhibitor docking, kinetic, and structure-activity relationship (SAR) studies have been used to guide ASADH inhibitor development. Elaboration of a core structure identified by FBDD has led to the synthesis of low micromolar inhibitors of the target enzyme, with high selectivity introduced between the Gram-negative and Gram-positive orthologs of ASADH. This new set of structures open a novel direction for the development of inhibitors against this validated drug-target enzyme. Copyright © 2015 Elsevier Ltd. All rights reserved.

Virtual screening of selective inhibitors of phosphopantetheine adenylyltransferase from Mycobacterium tuberculosis

Science.gov (United States)

Podshivalov, D. D.; Timofeev, V. I.; Sidorov-Biryukov, D. D.; Kuranova, I. P.

2017-05-01

Bacterial phosphopantetheine adenylyltransferase from Mycobacterium tuberculosis (PPAT Mt) is a convenient target protein for the directed search for selective inhibitors as potent antituberculosis drugs. Four compounds suitable for the detailed investigation of their interactions with PPAT Mt were found by virtual screening. The active-site region of the enzyme was chosen as the ligand-binding site. The positions of the ligands found by the docking were refined by molecular dynamics simulation. The nearest environment of the ligands, the positions of which in the active site of the enzyme were found in a computational experiment, was analyzed. The compounds under consideration were shown to directly interact with functionally important active-site amino-acid residues and block access of substrates to the active site. Therefore, these compounds can be used for the design of selective inhibitors of PPAT Mt as potent antituberculosis drugs.

Designing Isoform-selective Inhibitors Against Classical HDACs for Effective Anticancer Therapy: Insight and Perspectives from In Silico.

Science.gov (United States)

Ganai, Shabir Ahmad

2018-01-01

Histone deacetylase inhibitors, the small molecules modulating the biological activity of histone deacetylases are emerging as potent chemotherapeutic agents. Despite their considerable therapeutic benefits in disease models, the lack of isoform specificity culminates in debilitating off target effects, raising serious concerns regarding their applicability. This emphasizes the pressing and unmet medical need of designing isoform selective inhibitors for safe and effective anticancer therapy. Keeping these grim facts in view, the current article sheds light on structural basis of off-targeting. Furthermore, the article discusses extensively the role of in silico strategies such as Molecular Docking, Molecular Dynamics Simulation and Energetically-optimized structure based pharmacophore approach in designing on-target inhibitors against classical HDACs. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Discovery of a selective catalytic p300/CBP inhibitor that targets lineage-specific tumours

DEFF Research Database (Denmark)

Lasko, Loren M; Jakob, Clarissa G; Edalji, Rohinton P

2017-01-01

-specific tumour types, including several haematological malignancies and androgen receptor-positive prostate cancer. A-485 inhibited the androgen receptor transcriptional program in both androgen-sensitive and castration-resistant prostate cancer and inhibited tumour growth in a castration-resistant xenograft...... to treat certain cancers, but progress on the development of drug-like histone actyltransferase inhibitors has lagged behind. The histone acetyltransferase paralogues p300 and CREB-binding protein (CBP) are key transcriptional co-activators that are essential for a multitude of cellular processes, and have...... also been implicated in human pathological conditions (including cancer). Current inhibitors of the p300 and CBP histone acetyltransferase domains, including natural products, bi-substrate analogues and the widely used small molecule C646, lack potency or selectivity. Here, we describe A-485, a potent...

Preferential Selectivity of Inhibitors with Human Tau Protein Kinase Gsk3 Elucidates Their Potential Roles for Off-Target Alzheimer’s Therapy

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Jagadeesh Kumar Dasappa

2013-01-01

Full Text Available Alzheimer’s disease (AD is a neurodegenerative disorder characterized by the accumulation of amyloid beta peptides (A and neurofibrillary tangles (NFTs. The abnormal phosphorylation of tau leads to the formation of NFTs produced by the action of tau kinases, resulting in the loss of neurons and synapse, leading to dementia. Hence, tau kinases have become potential drug target candidates for small molecule inhibitors. With an aim to explore the identification of a common inhibitor, this investigation was undertaken towards analyzing all 10 tau kinases which are implicated in phosphorylation of AD. A set of 7 inhibitors with varied scaffolds were collected from the Protein Data Bank (PDB. The analysis, involving multiple sequence alignment, 3D structural alignment, catalytic active site overlap, and docking studies, has enabled elucidation of the pharmacophoric patterns for the class of 7 inhibitors. Our results divulge that tau protein kinases share a specific set of conserved structural elements for the binding of inhibitors and ATP, respectively. The scaffold of 3-aminopyrrolidine (inhibitor 6 exhibits high preferential affinity with GSK3. Surprisingly, the PDB does not contain the structural details of GSK3 with this specific inhibitor. Thus, our investigations provide vital clues towards design of novel off-target drugs for Alzheimer’s.

Mapping in vivo target interaction profiles of covalent inhibitors using chemical proteomics with label-free quantification.

Science.gov (United States)

van Rooden, Eva J; Florea, Bogdan I; Deng, Hui; Baggelaar, Marc P; van Esbroeck, Annelot C M; Zhou, Juan; Overkleeft, Herman S; van der Stelt, Mario

2018-04-01

Activity-based protein profiling (ABPP) has emerged as a valuable chemical proteomics method to guide the therapeutic development of covalent drugs by assessing their on-target engagement and off-target activity. We recently used ABPP to determine the serine hydrolase interaction landscape of the experimental drug BIA 10-2474, thereby providing a potential explanation for the adverse side effects observed with this compound. ABPP allows mapping of protein interaction landscapes of inhibitors in cells, tissues and animal models. Whereas our previous protocol described quantification of proteasome activity using stable-isotope labeling, this protocol describes the procedures for identifying the in vivo selectivity profile of covalent inhibitors with label-free quantitative proteomics. The optimization of our protocol for label-free quantification methods results in high proteome coverage and allows the comparison of multiple biological samples. We demonstrate our protocol by assessing the protein interaction landscape of the diacylglycerol lipase inhibitor DH376 in mouse brain, liver, kidney and testes. The stages of the protocol include tissue lysis, probe incubation, target enrichment, sample preparation, liquid chromatography-mass spectrometry (LC-MS) measurement, data processing and analysis. This approach can be used to study target engagement in a native proteome and to identify potential off targets for the inhibitor under investigation. The entire protocol takes at least 4 d, depending on the number of samples.

Development of dihydropyridone indazole amides as selective Rho-kinase inhibitors.

Science.gov (United States)

Goodman, Krista B; Cui, Haifeng; Dowdell, Sarah E; Gaitanopoulos, Dimitri E; Ivy, Robert L; Sehon, Clark A; Stavenger, Robert A; Wang, Gren Z; Viet, Andrew Q; Xu, Weiwei; Ye, Guosen; Semus, Simon F; Evans, Christopher; Fries, Harvey E; Jolivette, Larry J; Kirkpatrick, Robert B; Dul, Edward; Khandekar, Sanjay S; Yi, Tracey; Jung, David K; Wright, Lois L; Smith, Gary K; Behm, David J; Bentley, Ross; Doe, Christopher P; Hu, Erding; Lee, Dennis

2007-01-11

Rho kinase (ROCK1) mediates vascular smooth muscle contraction and is a potential target for the treatment of hypertension and related disorders. Indazole amide 3 was identified as a potent and selective ROCK1 inhibitor but possessed poor oral bioavailability. Optimization of this lead resulted in the discovery of a series of dihydropyridones, exemplified by 13, with improved pharmacokinetic parameters relative to the initial lead. Indazole substitution played a critical role in decreasing clearance and improving oral bioavailability.

Furan-2-ylmethylene thiazolidinediones as novel, potent, and selective inhibitors of phosphoinositide 3-kinase gamma.

Science.gov (United States)

Pomel, Vincent; Klicic, Jasna; Covini, David; Church, Dennis D; Shaw, Jeffrey P; Roulin, Karen; Burgat-Charvillon, Fabienne; Valognes, Delphine; Camps, Montserrat; Chabert, Christian; Gillieron, Corinne; Françon, Bernard; Perrin, Dominique; Leroy, Didier; Gretener, Denise; Nichols, Anthony; Vitte, Pierre Alain; Carboni, Susanna; Rommel, Christian; Schwarz, Matthias K; Rückle, Thomas

2006-06-29

Class I phosphoinositide 3-kinases (PI3Ks), in particular PI3Kgamma, have become attractive drug targets for inflammatory and autoimmune diseases. Here, we disclose a novel series of furan-2-ylmethylene thiazolidinediones as selective, ATP-competitive PI3Kgamma inhibitors. Structure-based design and X-ray crystallography of complexes formed by inhibitors bound to PI3Kgamma identified key pharmacophore features for potency and selectivity. An acidic NH group on the thiazolidinedione moiety and a hydroxy group on the furan-2-yl-phenyl part of the molecule play crucial roles in binding to PI3K and contribute to class IB PI3K selectivity. Compound 26 (AS-252424), a potent and selective small-molecule PI3Kgamma inhibitor emerging from these efforts, was further profiled in three different cellular PI3K assays and shown to be selective for class IB PI3K-mediated cellular effects. Oral administration of 26 in a mouse model of acute peritonitis led to a significant reduction of leukocyte recruitment.

The role of multikinase inhibitors target therapy in radioiodine-resistant differentiated thyroid cancer

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P O Rumyantsev

2015-06-01

Full Text Available About 5-15% of patients with differentiated thyroid cancer (DTC primary or within follow-up have had distant metastases or inoperable tumor mass that are resistant to radioiodine therapy as well as dramatically deteriorate survival prognosis. Other treatment modalities (radiotherapy, chemotherapy etc. also ineffective. Certain expectances are associated with target therapy with multikinase inhibitors with are selectively blocking onco-kinase molecular pathways. This review is devoted to analysis of those multikinase inhibitors which have been implemented in patients with radioiodine DTC. Comparative analysis of two most perspective multikinase inhibitors (sorafenib and lenvatinib with evaluation of efficacy and adverse effects was conducted. Both of them successfully underwent 3 rd phase of clinical trial and were recommended as treatment of choice in progressive radioiodine-resistant DTC patients.

Discovery and optimization of potent and selective imidazopyridine and imidazopyridazine mTOR inhibitors.

Science.gov (United States)

Peterson, Emily A; Boezio, Alessandro A; Andrews, Paul S; Boezio, Christiane M; Bush, Tammy L; Cheng, Alan C; Choquette, Deborah; Coats, James R; Colletti, Adria E; Copeland, Katrina W; DuPont, Michelle; Graceffa, Russell; Grubinska, Barbara; Kim, Joseph L; Lewis, Richard T; Liu, Jingzhou; Mullady, Erin L; Potashman, Michele H; Romero, Karina; Shaffer, Paul L; Stanton, Mary K; Stellwagen, John C; Teffera, Yohannes; Yi, Shuyan; Cai, Ti; La, Daniel S

2012-08-01

mTOR is a critical regulator of cellular signaling downstream of multiple growth factors. The mTOR/PI3K/AKT pathway is frequently mutated in human cancers and is thus an important oncology target. Herein we report the evolution of our program to discover ATP-competitive mTOR inhibitors that demonstrate improved pharmacokinetic properties and selectivity compared to our previous leads. Through targeted SAR and structure-guided design, new imidazopyridine and imidazopyridazine scaffolds were identified that demonstrated superior inhibition of mTOR in cellular assays, selectivity over the closely related PIKK family and improved in vivo clearance over our previously reported benzimidazole series. Copyright © 2012. Published by Elsevier Ltd.

High throughput in vivo protease inhibitor selection platform

DEFF Research Database (Denmark)

2017-01-01

The invention relates to a recombinant microbial cell comprising a selection platform for screening for a protease inhibitor, wherein the platform comprises transgenes encoding a protease having selective peptide bond cleavage activity at a recognition site amino acid sequence; and transgenes...... platform for screening for a protease inhibitor....

Selective and membrane-permeable small molecule inhibitors of nicotinamide N-methyltransferase reverse high fat diet-induced obesity in mice.

Science.gov (United States)

Neelakantan, Harshini; Vance, Virginia; Wetzel, Michael D; Wang, Hua-Yu Leo; McHardy, Stanton F; Finnerty, Celeste C; Hommel, Jonathan D; Watowich, Stanley J

2018-01-01

There is a critical need for new mechanism-of-action drugs that reduce the burden of obesity and associated chronic metabolic comorbidities. A potentially novel target to treat obesity and type 2 diabetes is nicotinamide-N-methyltransferase (NNMT), a cytosolic enzyme with newly identified roles in cellular metabolism and energy homeostasis. To validate NNMT as an anti-obesity drug target, we investigated the permeability, selectivity, mechanistic, and physiological properties of a series of small molecule NNMT inhibitors. Membrane permeability of NNMT inhibitors was characterized using parallel artificial membrane permeability and Caco-2 cell assays. Selectivity was tested against structurally-related methyltransferases and nicotinamide adenine dinucleotide (NAD + ) salvage pathway enzymes. Effects of NNMT inhibitors on lipogenesis and intracellular levels of metabolites, including NNMT reaction product 1-methylnicotianamide (1-MNA) were evaluated in cultured adipocytes. Effects of a potent NNMT inhibitor on obesity measures and plasma lipid were assessed in diet-induced obese mice fed a high-fat diet. Methylquinolinium scaffolds with primary amine substitutions displayed high permeability from passive and active transport across membranes. Importantly, methylquinolinium analogues displayed high selectivity, not inhibiting related SAM-dependent methyltransferases or enzymes in the NAD + salvage pathway. NNMT inhibitors reduced intracellular 1-MNA, increased intracellular NAD + and S-(5'-adenosyl)-l-methionine (SAM), and suppressed lipogenesis in adipocytes. Treatment of diet-induced obese mice systemically with a potent NNMT inhibitor significantly reduced body weight and white adipose mass, decreased adipocyte size, and lowered plasma total cholesterol levels. Notably, administration of NNMT inhibitors did not impact total food intake nor produce any observable adverse effects. These results support development of small molecule NNMT inhibitors as therapeutics to

Effective DNA Inhibitors of Cathepsin G by In Vitro Selection

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Gatto, Barbara; Vianini, Elena; Lucatello, Lorena; Sissi, Claudia; Moltrasio, Danilo; Pescador, Rodolfo; Porta, Roberto; Palumbo, Manlio

2008-01-01

Cathepsin G (CatG) is a chymotrypsin-like protease released upon degranulation of neutrophils. In several inflammatory and ischaemic diseases the impaired balance between CatG and its physiological inhibitors leads to tissue destruction and platelet aggregation. Inhibitors of CatG are suitable for the treatment of inflammatory diseases and procoagulant conditions. DNA released upon the death of neutrophils at injury sites binds CatG. Moreover, short DNA fragments are more inhibitory than genomic DNA. Defibrotide, a single stranded polydeoxyribonucleotide with antithrombotic effect is also a potent CatG inhibitor. Given the above experimental evidences we employed a selection protocol to assess whether DNA inhibition of CatG may be ascribed to specific sequences present in defibrotide DNA. A Selex protocol was applied to identify the single-stranded DNA sequences exhibiting the highest affinity for CatG, the diversity of a combinatorial pool of oligodeoxyribonucleotides being a good representation of the complexity found in defibrotide. Biophysical and biochemical studies confirmed that the selected sequences bind tightly to the target enzyme and also efficiently inhibit its catalytic activity. Sequence analysis carried out to unveil a motif responsible for CatG recognition showed a recurrence of alternating TG repeats in the selected CatG binders, adopting an extended conformation that grants maximal interaction with the highly charged protein surface. This unprecedented finding is validated by our results showing high affinity and inhibition of CatG by specific DNA sequences of variable length designed to maximally reduce pairing/folding interactions. PMID:19325843

Effective DNA Inhibitors of Cathepsin G by In Vitro Selection

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Manlio Palumbo

2008-06-01

Full Text Available Cathepsin G (CatG is a chymotrypsin-like protease released upon degranulation of neutrophils. In several inflammatory and ischaemic diseases the impaired balance between CatG and its physiological inhibitors leads to tissue destruction and platelet aggregation. Inhibitors of CatG are suitable for the treatment of inflammatory diseases and procoagulant conditions. DNA released upon the death of neutrophils at injury sites binds CatG. Moreover, short DNA fragments are more inhibitory than genomic DNA. Defibrotide, a single stranded polydeoxyribonucleotide with antithrombotic effect is also a potent CatG inhibitor. Given the above experimental evidences we employed a selection protocol to assess whether DNA inhibition of CatG may be ascribed to specific sequences present in defibrotide DNA. A Selex protocol was applied to identify the single-stranded DNA sequences exhibiting the highest affinity for CatG, the diversity of a combinatorial pool of oligodeoxyribonucleotides being a good representation of the complexity found in defibrotide. Biophysical and biochemical studies confirmed that the selected sequences bind tightly to the target enzyme and also efficiently inhibit its catalytic activity. Sequence analysis carried out to unveil a motif responsible for CatG recognition showed a recurrence of alternating TG repeats in the selected CatG binders, adopting an extended conformation that grants maximal interaction with the highly charged protein surface. This unprecedented finding is validated by our results showing high affinity and inhibition of CatG by specific DNA sequences of variable length designed to maximally reduce pairing/folding interactions.

Fasxiator, a novel factor XIa inhibitor from snake venom, and its site-specific mutagenesis to improve potency and selectivity.

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Chen, W; Carvalho, L P D; Chan, M Y; Kini, R M; Kang, T S

2015-02-01

Bleeding remains a major limitation of standard anticoagulant drugs that target the extrinsic and common coagulation pathways. Recently, intrinsic coagulation factors are increasingly being investigated as alternative targets for developing anticoagulant drugs with lower bleeding risk. Goals were to (i) identify novel anticoagulants selectively targeting intrinsic coagulation pathway and (ii) characterize and further improve the properties of the identified anticoagulants. We have isolated and sequenced a specific factor XIa (FXIa) inhibitor, henceforth named Fasxiator, from the venom of the banded krait snake, Bungarus fasciatus. It is a Kunitz-type protease inhibitor that prolonged activated partial thromboplastin time without significant effects on prothrombin time. Fasxiator was recombinantly expressed (rFasxiator), purified, and characterized to be a slow-type inhibitor of FXIa that exerts its anticoagulant activities (doubled activated partial thromboplastin time at ~ 3 μmol L(-1) ) by selectively inhibiting human FXIa in in vitro assays. A series of mutants were subsequently generated to improve the potency and selectivity of recombinant rFasxiator. rFasxiatorN17R,L19E showed the best balance between potency (IC50 ~ 1 nmol L(-1) ) and selectivity (> 100 times). rFasxiatorN17R,L19E is a competitive slow-type inhibitor of FXIa (Ki  = 0.86 nmol L(-1) ), possesses anticoagulant activity that is ~ 10 times stronger in human plasma than in murine plasma, and prolonged the occlusion time of mice carotid artery in FeCl3 -induced thrombosis models. We have isolated an exogenous FXIa specific inhibitor, engineered it to improve its potency by ~ 1000 times and demonstrated its in vitro and in vivo efficacy. These proof-of-principle data supported the further development of Fasxiator as a novel anticoagulant candidate. © 2014 International Society on Thrombosis and Haemostasis.

Adaptive evolution and elucidating the potential inhibitor against schizophrenia to target DAOA (G72 isoforms

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Sehgal SA

2015-07-01

Full Text Available Sheikh Arslan Sehgal,1,2 Shazia Mannan,2,* Sumaira Kanwal,2,* Ishrat Naveed,1 Asif Mir1 1Department of Bioinformatics and Biotechnology, International Islamic University, Islamabad, Pakistan; 2Department of Biosciences, COMSATS Institute of Information Technology, Sahiwal, Pakistan *These authors contributed equally to this work Abstract: Schizophrenia (SZ, a chronic mental and heritable disorder characterized by neurophysiological impairment and neuropsychological abnormalities, is strongly associated with d-amino acid oxidase activator (DAOA, G72. Research studies emphasized that overexpression of DAOA may be responsible for improper functioning of neurotransmitters, resulting in neurological disorders like SZ. In the present study, a hybrid approach of comparative modeling and molecular docking followed by inhibitor identification and structure modeling was employed. Screening was performed by two-dimensional similarity search against selected inhibitor, keeping in view the physiochemical properties of the inhibitor. Here, we report an inhibitor compound which showed maximum binding affinity against four selected isoforms of DAOA. Docking studies revealed that Glu-53, Thr-54, Lys-58, Val-85, Ser-86, Tyr-87, Leu-88, Glu-90, Leu-95, Val-98, Ser-100, Glu-112, Tyr-116, Lys-120, Asp-121, and Arg-122 are critical residues for receptor–ligand interaction. The C-terminal of selected isoforms is conserved, and binding was observed on the conserved region of isoforms. We propose that selected inhibitor might be more potent on the basis of binding energy values. Further analysis of this inhibitor through site-directed mutagenesis could be helpful for exploring the details of ligand-binding pockets. Overall, the findings of this study may be helpful in designing novel therapeutic targets to cure SZ. Keywords: schizophrenia, bioinformatics, modeling, docking, DAOA, G72, DAO, computer-aided drug designing, phylogenetic analysis, d-amino acid oxidase

Targeting the active site of the placental isozyme of alkaline phosphatase by phage-displayed scFv antibodies selected by a specific uncompetitive inhibitor

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Kala Mrinalini

2005-12-01

Full Text Available Abstract Background The isozymes of alkaline phosphatase, the tissue non-specific, intestinal and placental, have similar properties and a high degree of identity. The placental isozyme (PLAP is an oncofetal antigen expressed in several malignancies including choriocarcinoma, seminoma and ovarian carcinoma. We had earlier attempted to isolate PLAP-specific scFv from a synthetic human immunoglobulin library but were unable to do so, presumably because of the similarity between the isozymes. In this work, we have employed a PLAP-specific uncompetitive inhibitor, L-Phe-Gly-Gly, to select isozyme specific scFvs. An uncompetitive inhibitor binds to the enzyme in the presence of substrate and stabilizes the enzyme-substrate complex. Several uncompetitive inhibitors have varying degrees of isozyme specificity for human alkaline phosphatase isozymes. A specific uncompetitive inhibitor would be able to unmask conformational differences between the otherwise very similar molecules. Also, such inhibitors would be directed to regions at/close to the active site of the enzyme. In this work, the library was first incubated with PLAP and the bound clones then eluted by incubation with L-Phe-Gly-Gly along with the substrate, para-nitro phenyl phosphate (pNPP. The scFvs were then studied with regard to the biochemical modulation of their binding, isozyme specificity and effect on enzyme activity. Results Of 13 clones studied initially, the binding of 9 was inhibited by L-Phe-Gly-Gly (with pNPP and 2 clones were inhibited by pNPP alone. Two clones had absolute and 2 clones had partial specificity to PLAP. Two clones were cross-reactive with only one other isozyme. Three scFv clones, having an accessible His6-tag, were purified and studied for their modulation of enzyme activity. All the three scFvs inhibited PLAP activity with the kinetics of competitive inhibition. Cell ELISA could demonstrate binding of the specific scFvs to the cell surface expressed PLAP

Effects of selective phosphodiesterases-4 inhibitors on learning and memory: a review of recent research.

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Peng, Sheng; Sun, Haiyan; Zhang, Xiaoqing; Liu, Gongjian; Wang, Guanglei

2014-09-01

Phosphodiesterase-4 (PDE-4) regulates the intracellular level of cyclic adenosine monophosphate. Recent studies demonstrated that PDE-4 inhibitors can counteract deficits in long-term memory caused by aging or increased expression of mutant forms of human amyloid precursor proteins, and can influence the process of memory function and cognitive enhancement. Therapeutics, such as ketamine, a drug used in clinical anesthesia, can also cause memory deficits as adverse effects. Targeting PDE-4 with selective inhibitors may offer a novel therapeutic strategy to prevent, slow the progress, and, eventually, treat memory deficits.

A novel cofactor-binding mode in bacterial IMP dehydrogenases explains inhibitor selectivity.

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Makowska-Grzyska, Magdalena; Kim, Youngchang; Maltseva, Natalia; Osipiuk, Jerzy; Gu, Minyi; Zhang, Minjia; Mandapati, Kavitha; Gollapalli, Deviprasad R; Gorla, Suresh Kumar; Hedstrom, Lizbeth; Joachimiak, Andrzej

2015-02-27

The steadily rising frequency of emerging diseases and antibiotic resistance creates an urgent need for new drugs and targets. Inosine 5'-monophosphate dehydrogenase (IMP dehydrogenase or IMPDH) is a promising target for the development of new antimicrobial agents. IMPDH catalyzes the oxidation of IMP to XMP with the concomitant reduction of NAD(+), which is the pivotal step in the biosynthesis of guanine nucleotides. Potent inhibitors of bacterial IMPDHs have been identified that bind in a structurally distinct pocket that is absent in eukaryotic IMPDHs. The physiological role of this pocket was not understood. Here, we report the structures of complexes with different classes of inhibitors of Bacillus anthracis, Campylobacter jejuni, and Clostridium perfringens IMPDHs. These structures in combination with inhibition studies provide important insights into the interactions that modulate selectivity and potency. We also present two structures of the Vibrio cholerae IMPDH in complex with IMP/NAD(+) and XMP/NAD(+). In both structures, the cofactor assumes a dramatically different conformation than reported previously for eukaryotic IMPDHs and other dehydrogenases, with the major change observed for the position of the NAD(+) adenosine moiety. More importantly, this new NAD(+)-binding site involves the same pocket that is utilized by the inhibitors. Thus, the bacterial IMPDH-specific NAD(+)-binding mode helps to rationalize the conformation adopted by several classes of prokaryotic IMPDH inhibitors. These findings offer a potential strategy for further ligand optimization. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

A Novel Cofactor-binding Mode in Bacterial IMP Dehydrogenases Explains Inhibitor Selectivity*

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Makowska-Grzyska, Magdalena; Kim, Youngchang; Maltseva, Natalia; Osipiuk, Jerzy; Gu, Minyi; Zhang, Minjia; Mandapati, Kavitha; Gollapalli, Deviprasad R.; Gorla, Suresh Kumar; Hedstrom, Lizbeth; Joachimiak, Andrzej

2015-01-01

The steadily rising frequency of emerging diseases and antibiotic resistance creates an urgent need for new drugs and targets. Inosine 5′-monophosphate dehydrogenase (IMP dehydrogenase or IMPDH) is a promising target for the development of new antimicrobial agents. IMPDH catalyzes the oxidation of IMP to XMP with the concomitant reduction of NAD+, which is the pivotal step in the biosynthesis of guanine nucleotides. Potent inhibitors of bacterial IMPDHs have been identified that bind in a structurally distinct pocket that is absent in eukaryotic IMPDHs. The physiological role of this pocket was not understood. Here, we report the structures of complexes with different classes of inhibitors of Bacillus anthracis, Campylobacter jejuni, and Clostridium perfringens IMPDHs. These structures in combination with inhibition studies provide important insights into the interactions that modulate selectivity and potency. We also present two structures of the Vibrio cholerae IMPDH in complex with IMP/NAD+ and XMP/NAD+. In both structures, the cofactor assumes a dramatically different conformation than reported previously for eukaryotic IMPDHs and other dehydrogenases, with the major change observed for the position of the NAD+ adenosine moiety. More importantly, this new NAD+-binding site involves the same pocket that is utilized by the inhibitors. Thus, the bacterial IMPDH-specific NAD+-binding mode helps to rationalize the conformation adopted by several classes of prokaryotic IMPDH inhibitors. These findings offer a potential strategy for further ligand optimization. PMID:25572472

Kinase inhibitors can produce off-target effects and activate linked pathways by retroactivity

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Wynn Michelle L

2011-10-01

Full Text Available Abstract Background It has been shown in experimental and theoretical work that covalently modified signaling cascades naturally exhibit bidirectional signal propagation via a phenomenon known as retroactivity. An important consequence of retroactivity, which arises due to enzyme sequestration in covalently modified signaling cascades, is that a downstream perturbation can produce a response in a component upstream of the perturbation without the need for explicit feedback connections. Retroactivity may, therefore, play an important role in the cellular response to a targeted therapy. Kinase inhibitors are a class of targeted therapies designed to interfere with a specific kinase molecule in a dysregulated signaling pathway. While extremely promising as anti-cancer agents, kinase inhibitors may produce undesirable off-target effects by non-specific interactions or pathway cross-talk. We hypothesize that targeted therapies such as kinase inhibitors can produce off-target effects as a consequence of retroactivity alone. Results We used a computational model and a series of simple signaling motifs to test the hypothesis. Our results indicate that within physiologically and therapeutically relevant ranges for all parameters, a targeted inhibitor can naturally induce an off-target effect via retroactivity. The kinetics governing covalent modification cycles in a signaling network were more important for propagating an upstream off-target effect in our models than the kinetics governing the targeted therapy itself. Our results also reveal the surprising and crucial result that kinase inhibitors have the capacity to turn "on" an otherwise "off" parallel cascade when two cascades share an upstream activator. Conclusions A proper and detailed characterization of a pathway's structure is important for identifying the optimal protein to target as well as what concentration of the targeted therapy is required to modulate the pathway in a safe and effective

Design, synthesis and biological evaluation of uncharged catechol derivatives as selective inhibitors of PTP1B.

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Li, Xiang-Qian; Xu, Qi; Luo, Jiao; Wang, Li-Jun; Jiang, Bo; Zhang, Ren-Shuai; Shi, Da-Yong

2017-08-18

Protein tyrosine phosphatases 1B (PTP1B) is a promising and validated therapeutic target to effectively treat T2DM and obesity. However, the development of charged PTP1B inhibitors was restricted due to their low cell permeability and poor bioavailability. Based on active natural products, two series of uncharged catechol derivatives were identified as PTP1B inhibitors by targeting a secondary aryl phosphate-binding site as well as the catalytic site. The most potent inhibitor 22 showed an IC 50 of 0.487 μM against PTP1B and strong selectivity (27-fold) over TCPTP. Kinetic studies were also performed that 22 act as a competitive PTP1B inhibitor. The treatment of C2C12 myotubes with 22 markedly increased the phosphorylation levels of IRβ, Akt and IRS1 phosphorylation. The similarity of its action profiling with that produced by insulin suggested its potential as a new non-insulin-dependent drug candidate. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Anticancer actions of lysosomally targeted inhibitor, LCL521, of acid ceramidase.

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Bai, Aiping; Mao, Cungui; Jenkins, Russell W; Szulc, Zdzislaw M; Bielawska, Alicja; Hannun, Yusuf A

2017-01-01

Acid ceramidase, which catalyzes ceramide hydrolysis to sphingosine and free fatty acid mainly in the lysosome, is being recognized as a potential therapeutic target for cancer. B13 is an effective and selective acid ceramidase inhibitor in vitro, but not as effective in cells due to poor access to the lysosomal compartment. In order to achieve targeting of B13 to the lysosome, we designed lysosomotropic N, N-dimethyl glycine (DMG)-conjugated B13 prodrug LCL521 (1,3-di-DMG-B13). Our previous results indicated the efficient delivery of B13 to the lysosome resulted in augmented effects of LCL521 on cellular acid ceramidase as evaluated by effects on substrate/product levels. Our current studies indicate that functionally, this translated into enhanced inhibition of cell proliferation. Moreover, there were greater synergistic effects of LCL521 with either ionizing radiation or Tamoxifen. Taken together, these results clearly indicate that compartmental targeting for the inhibition of acid ceramidase is an efficient and valuable therapeutic strategy.

Epigenetic Mechanisms Regulating Adaptive Responses to Targeted Kinase Inhibitors in Cancer.

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Angus, Steven P; Zawistowski, Jon S; Johnson, Gary L

2018-01-06

Although targeted inhibition of oncogenic kinase drivers has achieved remarkable patient responses in many cancers, the development of resistance has remained a significant challenge. Numerous mechanisms have been identified, including the acquisition of gatekeeper mutations, activating pathway mutations, and copy number loss or gain of the driver or alternate nodes. These changes have prompted the development of kinase inhibitors with increased selectivity, use of second-line therapeutics to overcome primary resistance, and combination treatment to forestall resistance. In addition to genomic resistance mechanisms, adaptive transcriptional and signaling responses seen in tumors are gaining appreciation as alterations that lead to a phenotypic state change-often observed as an epithelial-to-mesenchymal shift or reversion to a cancer stem cell-like phenotype underpinned by remodeling of the epigenetic landscape. This epigenomic modulation driving cell state change is multifaceted and includes modulation of repressive and activating histone modifications, DNA methylation, enhancer remodeling, and noncoding RNA species. Consequently, the combination of kinase inhibitors with drugs targeting components of the transcriptional machinery and histone-modifying enzymes has shown promise in preclinical and clinical studies. Here, we review mechanisms of resistance to kinase inhibition in cancer, with special emphasis on the rewired kinome and transcriptional signaling networks and the potential vulnerabilities that may be exploited to overcome these adaptive signaling changes.

Selectivity analysis of protein kinase CK2 inhibitors DMAT, TBB and resorufin in cisplatin-induced stress responses

DEFF Research Database (Denmark)

Fritz, Gerhard; Issinger, Olaf-Georg; Olsen, Birgitte Brinkmann

2009-01-01

Targeting protein kinases as a therapeutic approach to treat various diseases, especially cancer is currently a fast growing business. Although many inhibitors are available, exhibiting remarkable potency, the major challenge is their selectivity. Here we show that the protein kinase CK2 inhibito...

Allosteric small-molecule kinase inhibitors

DEFF Research Database (Denmark)

Wu, Peng; Clausen, Mads Hartvig; Nielsen, Thomas E.

2015-01-01

current barriers of kinase inhibitors, including poor selectivity and emergence of drug resistance. In spite of the small number of identified allosteric inhibitors in comparison with that of inhibitors targeting the ATP pocket, encouraging results, such as the FDA-approval of the first small...

Selectivity Profiling and Biological Activity of Novel β-Carbolines as Potent and Selective DYRK1 Kinase Inhibitors.

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Katharina Rüben

Full Text Available DYRK1A is a pleiotropic protein kinase with diverse functions in cellular regulation, including cell cycle control, neuronal differentiation, and synaptic transmission. Enhanced activity and overexpression of DYRK1A have been linked to altered brain development and function in Down syndrome and neurodegenerative diseases such as Alzheimer's disease. The β-carboline alkaloid harmine is a high affinity inhibitor of DYRK1A but suffers from the drawback of inhibiting monoamine oxidase A (MAO-A with even higher potency. Here we characterized a series of novel harmine analogs with minimal or absent MAO-A inhibitory activity. We identified several inhibitors with submicromolar potencies for DYRK1A and selectivity for DYRK1A and DYRK1B over the related kinases DYRK2 and HIPK2. An optimized inhibitor, AnnH75, inhibited CLK1, CLK4, and haspin/GSG2 as the only off-targets in a panel of 300 protein kinases. In cellular assays, AnnH75 dose-dependently reduced the phosphorylation of three known DYRK1A substrates (SF3B1, SEPT4, and tau without negative effects on cell viability. AnnH75 inhibited the cotranslational tyrosine autophosphorylation of DYRK1A and threonine phosphorylation of an exogenous substrate protein with similar potency. In conclusion, we have characterized an optimized β-carboline inhibitor as a highly selective chemical probe that complies with desirable properties of drug-like molecules and is suitable to interrogate the function of DYRK1A in biological studies.

Mutational analysis of target enzyme recognition of the beta-trefoil fold barley alpha-amylase/subtilisin inhibitor

DEFF Research Database (Denmark)

Bønsager, Birgit Christine; Nielsen, Per K.; Abou Hachem, Maher

2005-01-01

The barley alpha-amylase/subtilisin inhibitor ( BASI) inhibits alpha-amylase 2 (AMY2) with subnanomolar affinity. The contribution of selected side chains of BASI to this high affinity is discerned in this study, and binding to other targets is investigated. Seven BASI residues along the AMY2-BASI...... interface and four residues in the putative protease-binding loop on the opposite side of the inhibitor were mutated. A total of 15 variants were compared with the wild type by monitoring the alpha-amylase and protease inhibitory activities using Blue Starch and azoalbumin, respectively, and the kinetics...

Selective Inhibitors of Protozoan Protein N-myristoyltransferases as Starting Points for Tropical Disease Medicinal Chemistry Programs

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Bell, Andrew S.; Mills, James E.; Williams, Gareth P.; Brannigan, James A.; Wilkinson, Anthony J.; Parkinson, Tanya; Leatherbarrow, Robin J.; Tate, Edward W.; Holder, Anthony A.; Smith, Deborah F.

2012-01-01

Inhibition of N-myristoyltransferase has been validated pre-clinically as a target for the treatment of fungal and trypanosome infections, using species-specific inhibitors. In order to identify inhibitors of protozoan NMTs, we chose to screen a diverse subset of the Pfizer corporate collection against Plasmodium falciparum and Leishmania donovani NMTs. Primary screening hits against either enzyme were tested for selectivity over both human NMT isoforms (Hs1 and Hs2) and for broad-spectrum anti-protozoan activity against the NMT from Trypanosoma brucei. Analysis of the screening results has shown that structure-activity relationships (SAR) for Leishmania NMT are divergent from all other NMTs tested, a finding not predicted by sequence similarity calculations, resulting in the identification of four novel series of Leishmania-selective NMT inhibitors. We found a strong overlap between the SARs for Plasmodium NMT and both human NMTs, suggesting that achieving an appropriate selectivity profile will be more challenging. However, we did discover two novel series with selectivity for Plasmodium NMT over the other NMT orthologues in this study, and an additional two structurally distinct series with selectivity over Leishmania NMT. We believe that release of results from this study into the public domain will accelerate the discovery of NMT inhibitors to treat malaria and leishmaniasis. Our screening initiative is another example of how a tripartite partnership involving pharmaceutical industries, academic institutions and governmental/non-governmental organisations such as Medical Research Council and Wellcome Trust can stimulate research for neglected diseases. PMID:22545171

Optimization of dipeptidic inhibitors of cathepsin L for improved Toxoplasma gondii selectivity and CNS permeability.

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Zwicker, Jeffery D; Diaz, Nicolas A; Guerra, Alfredo J; Kirchhoff, Paul D; Wen, Bo; Sun, Duxin; Carruthers, Vern B; Larsen, Scott D

2018-06-01

The neurotropic protozoan Toxoplasma gondii is the second leading cause of death due to foodborne illness in the US, and has been designated as one of five neglected parasitic infections by the Center for Disease Control and Prevention. Currently, no treatment options exist for the chronic dormant-phase Toxoplasma infection in the central nervous system (CNS). T. gondii cathepsin L (TgCPL) has recently been implicated as a novel viable target for the treatment of chronic toxoplasmosis. In this study, we report the first body of SAR work aimed at developing potent inhibitors of TgCPL with selectivity vs the human cathepsin L. Starting from a known inhibitor of human cathepsin L, and guided by structure-based design, we were able to modulate the selectivity for Toxoplasma vs human CPL by nearly 50-fold while modifying physiochemical properties to be more favorable for metabolic stability and CNS penetrance. The overall potency of our inhibitors towards TgCPL was improved from 2 μM to as low as 110 nM and we successfully demonstrated that an optimized analog 18b is capable of crossing the BBB (0.5 brain/plasma). This work is an important first step toward development of a CNS-penetrant probe to validate TgCPL as a feasible target for the treatment of chronic toxoplasmosis. Copyright © 2018 Elsevier Ltd. All rights reserved.

DMPD: Ubiquitin: tool and target for intracellular NF-kappaB inhibitors. [Dynamic Macrophage Pathway CSML Database

Lifescience Database Archive (English)

Full Text Available 16982211 Ubiquitin: tool and target for intracellular NF-kappaB inhibitors. Wullaer...vg) (.html) (.csml) Show Ubiquitin: tool and target for intracellular NF-kappaB inhibitors. PubmedID 1698221...1 Title Ubiquitin: tool and target for intracellular NF-kappaB inhibitors. Author

Inferring selection in the Anopheles gambiae species complex: an example from immune-related serine protease inhibitors

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Little Tom J

2009-06-01

Full Text Available Abstract Background Mosquitoes of the Anopheles gambiae species complex are the primary vectors of human malaria in sub-Saharan Africa. Many host genes have been shown to affect Plasmodium development in the mosquito, and so are expected to engage in an evolutionary arms race with the pathogen. However, there is little conclusive evidence that any of these mosquito genes evolve rapidly, or show other signatures of adaptive evolution. Methods Three serine protease inhibitors have previously been identified as candidate immune system genes mediating mosquito-Plasmodium interaction, and serine protease inhibitors have been identified as hot-spots of adaptive evolution in other taxa. Population-genetic tests for selection, including a recent multi-gene extension of the McDonald-Kreitman test, were applied to 16 serine protease inhibitors and 16 other genes sampled from the An. gambiae species complex in both East and West Africa. Results Serine protease inhibitors were found to show a marginally significant trend towards higher levels of amino acid diversity than other genes, and display extensive genetic structuring associated with the 2La chromosomal inversion. However, although serpins are candidate targets for strong parasite-mediated selection, no evidence was found for rapid adaptive evolution in these genes. Conclusion It is well known that phylogenetic and population history in the An. gambiae complex can present special problems for the application of standard population-genetic tests for selection, and this may explain the failure of this study to detect selection acting on serine protease inhibitors. The pitfalls of uncritically applying these tests in this species complex are highlighted, and the future prospects for detecting selection acting on the An. gambiae genome are discussed.

Use of selective-serotonin reuptake inhibitors and platelet aggregation inhibitors among individuals with co-occurring atherosclerotic cardiovascular disease and depression or anxiety

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J Douglas Thornton

2016-12-01

Full Text Available Objective: Medications commonly used to treat heart disease, anxiety, and depression can interact resulting in an increased risk of bleeding, warranting a cautious approach in medical decision making. This retrospective, descriptive study examined the prevalence and the factors associated with the use of both selective-serotonin reuptake inhibitor and platelet aggregation inhibitor among individuals with co-occurring atherosclerotic cardiovascular disease and anxiety or depression. Methods: Respondents aged 22 years and older, alive throughout the study period, and diagnosed with co-occurring atherosclerotic cardiovascular disease and anxiety or depression (n = 1507 in years 2007 through 2013 of the Medical Expenditures Panel Survey were included. The use of treatment was grouped as follows: selective-serotonin reuptake inhibitor and platelet aggregation inhibitor, selective-serotonin reuptake inhibitor or platelet aggregation inhibitor, and neither selective-serotonin reuptake inhibitor nor platelet aggregation inhibitor. Results: Overall, 16.5% used both selective-serotonin reuptake inhibitor and platelet aggregation inhibitor, 61.2% used selective-serotonin reuptake inhibitor or platelet aggregation inhibitor, and 22.3% used neither selective-serotonin reuptake inhibitor nor platelet aggregation inhibitor. Respondents aged over 65 years (adjusted odds ratio = 1.93 (95% confidence interval = 1.08–3.45 and having a diagnosis of diabetes (adjusted odds ratio = 1.63 (95% confidence interval = 1.15–2.31 and hypertension (adjusted odds ratio = 1.84 (95% confidence interval = 1.04–3.27 were more likely to be prescribed the combination. Conclusion: The drug interaction was prevalent in patients who are already at higher risk of health disparities and worse outcomes thus requiring vigilant evaluation.

Selective small-chemical inhibitors of protein arginine methyltransferase 5 with anti-lung cancer activity.

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Gui-Mei Kong

Full Text Available Protein arginine methyltransferase 5 (PRMT5 plays critical roles in a wide variety of biological processes, including tumorigenesis. By screening a library of small chemical compounds, we identified eight compounds that selectively inhibit the PRMT5 enzymatic activity, with IC50 values ranging from 0.1 to 6 μM. Molecular docking simulation and site-directed mutagenesis indicated that identified compounds target the substrate-binding site in PRMT5. Treatment of lung cancer cells with identified inhibitors led to inhibition of the symmetrical arginine methylation of SmD3 and histones and the cellular proliferation. Oral administration of the inhibitor demonstrated antitumor activity in a lung tumor xenograft model. Thus, identified PRMT5-specific small-molecule inhibitors would help elucidate the biological roles of PRMT5 and serve as lead compounds for future drug development.

Rational optimization of drug-target residence time: Insights from inhibitor binding to the S. aureus FabI enzyme-product complex

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Chang, Andrew; Schiebel, Johannes; Yu, Weixuan; Bommineni, Gopal R.; Pan, Pan; Baxter, Michael V.; Khanna, Avinash; Sotriffer, Christoph A.; Kisker, Caroline; Tonge, Peter J.

2013-01-01

Drug-target kinetics has recently emerged as an especially important facet of the drug discovery process. In particular, prolonged drug-target residence times may confer enhanced efficacy and selectivity in the open in vivo system. However, the lack of accurate kinetic and structural data for series of congeneric compounds hinders the rational design of inhibitors with decreased off-rates. Therefore, we chose the Staphylococcus aureus enoyl-ACP reductase (saFabI) - an important target for the development of new anti-staphylococcal drugs - as a model system to rationalize and optimize the drug-target residence time on a structural basis. Using our new, efficient and widely applicable mechanistically informed kinetic approach, we obtained a full characterization of saFabI inhibition by a series of 20 diphenyl ethers complemented by a collection of 9 saFabI-inhibitor crystal structures. We identified a strong correlation between the affinities of the investigated saFabI diphenyl ether inhibitors and their corresponding residence times, which can be rationalized on a structural basis. Due to its favorable interactions with the enzyme, the residence time of our most potent compound exceeds 10 hours. In addition, we found that affinity and residence time in this system can be significantly enhanced by modifications predictable by a careful consideration of catalysis. Our study provides a blueprint for investigating and prolonging drug-target kinetics and may aid in the rational design of long-residence-time inhibitors targeting the essential saFabI enzyme. PMID:23697754

Chemical Proteomics Reveals Ferrochelatase as a Common Off-target of Kinase Inhibitors.

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Klaeger, Susan; Gohlke, Bjoern; Perrin, Jessica; Gupta, Vipul; Heinzlmeir, Stephanie; Helm, Dominic; Qiao, Huichao; Bergamini, Giovanna; Handa, Hiroshi; Savitski, Mikhail M; Bantscheff, Marcus; Médard, Guillaume; Preissner, Robert; Kuster, Bernhard

2016-05-20

Many protein kinases are valid drug targets in oncology because they are key components of signal transduction pathways. The number of clinical kinase inhibitors is on the rise, but these molecules often exhibit polypharmacology, potentially eliciting desired and toxic effects. Therefore, a comprehensive assessment of a compound's target space is desirable for a better understanding of its biological effects. The enzyme ferrochelatase (FECH) catalyzes the conversion of protoporphyrin IX into heme and was recently found to be an off-target of the BRAF inhibitor Vemurafenib, likely explaining the phototoxicity associated with this drug in melanoma patients. This raises the question of whether FECH binding is a more general feature of kinase inhibitors. To address this, we applied a chemical proteomics approach using kinobeads to evaluate 226 clinical kinase inhibitors for their ability to bind FECH. Surprisingly, low or submicromolar FECH binding was detected for 29 of all compounds tested and isothermal dose response measurements confirmed target engagement in cells. We also show that Vemurafenib, Linsitinib, Neratinib, and MK-2461 reduce heme levels in K562 cells, verifying that drug binding leads to a loss of FECH activity. Further biochemical and docking experiments identified the protoporphyrin pocket in FECH as one major drug binding site. Since the genetic loss of FECH activity leads to photosensitivity in humans, our data strongly suggest that FECH inhibition by kinase inhibitors is the molecular mechanism triggering photosensitivity in patients. We therefore suggest that a FECH assay should generally be part of the preclinical molecular toxicology package for the development of kinase inhibitors.

Acquisition of a potent and selective TC-PTP inhibitor via a stepwise fluorophore-tagged combinatorial synthesis and screening strategy.

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Zhang, Sheng; Chen, Lan; Luo, Yong; Gunawan, Andrea; Lawrence, David S; Zhang, Zhong-Yin

2009-09-16

Protein tyrosine phosphatases (PTPs) regulate a broad range of cellular processes including proliferation, differentiation, migration, apoptosis, and immune responses. Dysfunction of PTP activity is associated with cancers, metabolic syndromes, and autoimmune disorders. Consequently, small molecule PTP inhibitors should serve not only as powerful tools to delineate the physiological roles of these enzymes in vivo but also as lead compounds for therapeutic development. We describe a novel stepwise fluorophore-tagged combinatorial library synthesis and competitive fluorescence polarization screening approach that transforms a weak and general PTP inhibitor into an extremely potent and selective TC-PTP inhibitor with highly efficacious cellular activity. The result serves as a proof-of-concept in PTP inhibitor development, as it demonstrates the feasibility of acquiring potent, yet highly selective, cell permeable PTP inhibitory agents. Given the general nature of the approach, this strategy should be applicable to other PTP targets.

Anticancer actions of lysosomally targeted inhibitor, LCL521, of acid ceramidase.

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Aiping Bai

Full Text Available Acid ceramidase, which catalyzes ceramide hydrolysis to sphingosine and free fatty acid mainly in the lysosome, is being recognized as a potential therapeutic target for cancer. B13 is an effective and selective acid ceramidase inhibitor in vitro, but not as effective in cells due to poor access to the lysosomal compartment. In order to achieve targeting of B13 to the lysosome, we designed lysosomotropic N, N-dimethyl glycine (DMG-conjugated B13 prodrug LCL521 (1,3-di-DMG-B13. Our previous results indicated the efficient delivery of B13 to the lysosome resulted in augmented effects of LCL521 on cellular acid ceramidase as evaluated by effects on substrate/product levels. Our current studies indicate that functionally, this translated into enhanced inhibition of cell proliferation. Moreover, there were greater synergistic effects of LCL521 with either ionizing radiation or Tamoxifen. Taken together, these results clearly indicate that compartmental targeting for the inhibition of acid ceramidase is an efficient and valuable therapeutic strategy.

Epitope-Targeting of Tertiary Protein Structure Enables Target-Guided Synthesis of a Potent in Cell Inhibitor of Botulinum Neurotoxin**

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Farrow, Blake; Wong, Michelle; Malette, Jacquie; Lai, Bert; Deyle, Kaycie M.; Das, Samir; Nag, Arundhati; Agnew, Heather D.; Heath, James R.

2015-01-01

Botulinum neurotoxin (BoNT) serotype A is the most lethal known toxin and has an occluded structure, which prevents direct inhibition of its active site before it enters the cytosol. Target-guided synthesis by in situ click chemistry is combined with synthetic epitope targeting to exploit the tertiary structure of the BoNT protein as a landscape for assembling a competitive inhibitor. A substrate-mimicking peptide macrocycle is used as a direct inhibitor of BoNT. An epitope-targeting in situ ...

Targeting Type 2 Diabetes with C-Glucosyl Dihydrochalcones as Selective Sodium Glucose Co-Transporter 2 (SGLT2) Inhibitors: Synthesis and Biological Evaluation.

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Jesus, Ana R; Vila-Viçosa, Diogo; Machuqueiro, Miguel; Marques, Ana P; Dore, Timothy M; Rauter, Amélia P

2017-01-26

Inhibiting glucose reabsorption by sodium glucose co-transporter proteins (SGLTs) in the kidneys is a relatively new strategy for treating type 2 diabetes. Selective inhibition of SGLT2 over SGLT1 is critical for minimizing adverse side effects associated with SGLT1 inhibition. A library of C-glucosyl dihydrochalcones and their dihydrochalcone and chalcone precursors was synthesized and tested as SGLT1/SGLT2 inhibitors using a cell-based fluorescence assay of glucose uptake. The most potent inhibitors of SGLT2 (IC 50 = 9-23 nM) were considerably weaker inhibitors of SGLT1 (IC 50 = 10-19 μM). They showed no effect on the sodium independent GLUT family of glucose transporters, and the most potent ones were not acutely toxic to cultured cells. The interaction of a C-glucosyl dihydrochalcone with a POPC membrane was modeled computationally, providing evidence that it is not a pan-assay interference compound. These results point toward the discovery of structures that are potent and highly selective inhibitors of SGLT2.

Insight into the mechanism of action and selectivity of caspase-3 reversible inhibitors through in silico studies

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Minini, Lucía; Ferraro, Florencia; Cancela, Saira; Merlino, Alicia

2017-11-01

Alzheimer's disease (AD) is the most prevalent neurodegenerative disorder worldwide for which there is currently no cure. Recently, caspase-3 has been proposed as a potential therapeutic target for treating AD. Since this enzyme is overexpressed in brains from AD patients its selective modulation by non-covalent inhibitors becomes an interesting strategy in the search of potential drugs against this neuropathology. With this in mind, we have combined molecular docking, molecular dynamics simulations and QM calculations of unliganded caspase-3 and caspase-7 and in complex with a series of known inhibitors of caspase-3 described in the literature in order to assess the structural features responsible for good inhibitory activity and selectivity against this potential target. This work has allowed us to identify hotspots for drug binding as well as the importance of shape and charge distribution for interacting into the substrate binding cleft or into the dimer interface in each enzyme. Our results showed that most selective compounds against caspsase-3 bind into the substrate binding cleft acting as competitive inhibitors whereas in caspase-7 they bind close to an allosteric site at the dimer interface but since they are weakly bound their presence would not be affecting enzyme dynamics or function. In addition, for both enzymes we have found evidence indicating that differences in shape and accessibility exist between the substrate binding site of each monomer which could be modulating the binding affinity of non-covalent molecules.

Discovery of N-(Naphtho[1,2-b]Furan-5-Yl Benzenesulfonamides as Novel Selective Inhibitors of Triple-Negative Breast Cancer (TNBC

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Ya Chen

2018-03-01

Full Text Available Any type of breast cancer not expressing genes of the estrogen receptor (ER, progesterone receptor (PR, or human epidermal growth factor receptor 2 (HER2 is referred to as triple-negative breast cancer (TNBC. Accordingly, TNBCs do not respond to hormonal therapies or medicines targeting the ER, PR, or HER2. Systemic chemotherapy is therefore the only treatment option available today and prognoses remain poor. We report the discovery and characterization of N-(naphtho[1,2-b]furan-5-ylbenzenesulfonamides as selective inhibitors of TNBCs. These inhibitors were identified by virtual screening and inhibited different TNBC cell lines with IC50 values of 2–3 μM. The compounds did not inhibit normal (i.e. MCF-7 and MCF-10A cells in vitro, indicating their selectivity against TNBC cells. Considering the selectivity of these inhibitors for TNBC, these compounds and analogs can serve as a promising starting point for further research on effective TNBC inhibitors.

Pathway-based identification of biomarkers for targeted therapeutics: personalized oncology with PI3K pathway inhibitors.

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Andersen, Jannik N; Sathyanarayanan, Sriram; Di Bacco, Alessandra; Chi, An; Zhang, Theresa; Chen, Albert H; Dolinski, Brian; Kraus, Manfred; Roberts, Brian; Arthur, William; Klinghoffer, Rich A; Gargano, Diana; Li, Lixia; Feldman, Igor; Lynch, Bethany; Rush, John; Hendrickson, Ronald C; Blume-Jensen, Peter; Paweletz, Cloud P

2010-08-04

Although we have made great progress in understanding the complex genetic alterations that underlie human cancer, it has proven difficult to identify which molecularly targeted therapeutics will benefit which patients. Drug-specific modulation of oncogenic signaling pathways in specific patient subpopulations can predict responsiveness to targeted therapy. Here, we report a pathway-based phosphoprofiling approach to identify and quantify clinically relevant, drug-specific biomarkers for phosphatidylinositol 3-kinase (PI3K) pathway inhibitors that target AKT, phosphoinositide-dependent kinase 1 (PDK1), and PI3K-mammalian target of rapamycin (mTOR). We quantified 375 nonredundant PI3K pathway-relevant phosphopeptides, all containing AKT, PDK1, or mitogen-activated protein kinase substrate recognition motifs. Of these phosphopeptides, 71 were drug-regulated, 11 of them by all three inhibitors. Drug-modulated phosphoproteins were enriched for involvement in cytoskeletal reorganization (filamin, stathmin, dynamin, PAK4, and PTPN14), vesicle transport (LARP1, VPS13D, and SLC20A1), and protein translation (S6RP and PRAS40). We then generated phosphospecific antibodies against selected, drug-regulated phosphorylation sites that would be suitable as biomarker tools for PI3K pathway inhibitors. As proof of concept, we show clinical translation feasibility for an antibody against phospho-PRAS40(Thr246). Evaluation of binding of this antibody in human cancer cell lines, a PTEN (phosphatase and tensin homolog deleted from chromosome 10)-deficient mouse prostate tumor model, and triple-negative breast tumor tissues showed that phospho-PRAS40(Thr246) positively correlates with PI3K pathway activation and predicts AKT inhibitor sensitivity. In contrast to phosphorylation of AKT(Thr308), the phospho-PRAS40(Thr246) epitope is highly stable in tissue samples and thus is ideal for immunohistochemistry. In summary, our study illustrates a rational approach for discovery of drug

Discovery and quantitative structure-activity relationship study of lepidopteran HMG-CoA reductase inhibitors as selective insecticides.

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Zang, Yang-Yang; Li, Yuan-Mei; Yin, Yue; Chen, Shan-Shan; Kai, Zhen-Peng

2017-09-01

In a previous study we have demonstrated that insect 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR) can be a potential selective insecticide target. Three series of inhibitors were designed on the basis of the difference in HMGR structures from Homo sapiens and Manduca sexta, with the aim of discovering potent selective insecticide candidates. An in vitro bioassay showed that gem-difluoromethylenated statin analogues have potent effects on JH biosynthesis of M. sexta and high selectivity between H. sapiens and M. sexta. All series II compounds {1,3,5-trisubstituted [4-tert-butyl 2-(5,5-difluoro-2,2-dimethyl-6-vinyl-4-yl) acetate] pyrazoles} have some effect on JH biosynthesis, whereas most of them are inactive on human HMGR. In particular, the IC 50 value of compound II-12 (37.8 nm) is lower than that of lovastatin (99.5 nm) and similar to that of rosuvastatin (24.2 nm). An in vivo bioassay showed that I-1, I-2, I-3 and II-12 are potential selective insecticides, especially for lepidopteran pest control. A predictable and statistically meaningful CoMFA model of 23 inhibitors (20 as training sets and three as test sets) was obtained with a value of q 2 and r 2 of 0.66 and 0.996 respectively. The final model suggested that a potent insect HMGR inhibitor should contain suitable small and non-electronegative groups in the ring part, and electronegative groups in the side chain. Four analogues were discovered as potent selective lepidopteran HMGR inhibitors, which can specifically be used for lepidopteran pest control. The CoMFA model will be useful for the design of new selective insect HMGR inhibitors that are structurally related to the training set compounds. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

PI3Kδ-selective and PI3Kα/δ-combinatorial inhibitors in clinical development for B-cell non-Hodgkin lymphoma.

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Lampson, Benjamin L; Brown, Jennifer R

2017-11-01

The efficacy of the prototypical phosphatidylinositol-3-kinase (PI3K) inhibitor idelalisib for the treatment of chronic lymphocytic leukemia (CLL) and indolent non-Hodgkin lymphoma (iNHL) has led to development of multiple compounds targeting this pathway. Areas Covered: We review the hypothesized therapeutic mechanisms of PI3K inhibitors, including abrogation of B cell receptor signaling, blockade of microenvironmental pro-survival signals, and enhancement of anti-tumor immunity. We examine toxicities of idelalisib, including bacterial infections (possibly secondary to drug-induced neutropenia), opportunistic infections (possibly attributable to on-target inhibition of T cell function), and organ toxicities such as transaminitis and enterocolitis (possibly autoimmune, secondary to on-target inhibition of p110δ in regulatory T cells). We evaluate PI3K inhibitors that have entered trials for the treatment of lymphoma, focusing on agents with selectivity for PI3Kα and PI3Kδ. Expert Opinion: PI3K inhibitors, particularly those that target p110δ, have robust efficacy in the treatment of CLL and iNHL. However, idelalisib has infectious and autoimmune toxicities that limit its use. Outside of trials, idelalisib should be restricted to CLL patients with progression on ibrutinib or iNHL patients with progression on two prior therapies. Whether newer PI3K inhibitors will demonstrate differentiated toxicity profiles in comparable patient populations while retaining efficacy remains to be seen.

Selective serotonin reuptake inhibitors and risk for gastrointestinal bleeding

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Batić-Mujanović Olivera

2014-01-01

Full Text Available The most of the known effects of selective serotonin reuptake inhibitors, beneficial or harmful, are associated with the inhibitory action of the serotonin reuptake transporter. This mechanism is present not only in neurons, but also in other cells such as platelets. Serotoninergic mechanism seems to have an important role in hemostasis, which has long been underestimated. Abnormal activation may lead to a prothrombotic state in patients treated with selective serotonin reuptake inhibitors. On one hand there may be an increased risk of bleeding, and on the other hand reduction in thrombotic risk may be possible. Serotonin is critical to maintain a platelet haemostatic function, such as platelet aggregation. Evidences from the studies support the hypothesis that antidepressants with a relevant blockade of action of serotonin reuptake mechanism may increase the risk of bleeding, which can occur anywhere in the body. Epidemiological evidences are, however, the most robust for upper gastrointestinal bleeding. It is estimated that this bleeding can occur in 1 in 100 to 1 in 1.000 patient-years of exposure to the high-affinity selective serotonin reuptake inhibitors, with very old patients at the highest risk. The increased risk may be of particular relevance when selective serotonin reuptake inhibitors are taken simultaneously with nonsteroidal anti-inflammatory drugs, low dose of aspirin or warfarin.

Tyrosine kinase, aurora kinase and leucine aminopeptidase as attractive drug targets in anticancer therapy - characterisation of their inhibitors.

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Ziemska, Joanna; Solecka, Jolanta

Cancers are the leading cause of deaths all over the world. Available anticancer agents used in clinics exhibit low therapeutic index and usually high toxicity. Wide spreading drug resistance of cancer cells induce a demanding need to search for new drug targets. Currently, many on-going studies on novel compounds with potent anticancer activity, high selectivity as well as new modes of action are conducted. In this work, we describe in details three enzyme groups, which are at present of extensive interest to medical researchers and pharmaceutical companies. These include receptor tyrosine kinases (e.g. EGFR enzymes) and non-receptor tyrosine kinases (Src enzymes), type A, B and C Aurora kinases and aminopeptidases, especially leucine aminopeptidase. We discuss classification of these enzymes, biochemistry as well as their role in the cell cycle under normal conditions and during cancerogenesis. Further on, the work describes enzyme inhibitors that are under in vitro, preclinical, clinical studies as well as drugs available on the market. Both, chemical structures of discovered inhibitors and the role of chemical moieties in novel drug design are discussed. Described enzymes play essential role in cell cycle, especially in mitosis (Aurora kinases), cell differentiation, growth and apoptosis (tyrosine kinases) as well as G1/S transition (leucine aminopeptidase). In cancer cells, they are overexpressed and only their inhibition may stop tumor progression. This review presents the clinical outcomes of selected inhibitors and argues the safety of drug usage in human volunteers. Clinical studies of EGFR and Src kinase inhibitors in different tumors clearly show the need for molecular selection of patients (to those with mutations in genes coding EGFR and Src) to achieve positive clinical response. Current data indicates the great necessity for new anticancer treatment and actions to limit off-target activity.

Selective elimination of neuroblastoma cells by synergistic effect of Akt kinase inhibitor and tetrathiomolybdate.

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Navrátilová, Jarmila; Karasová, Martina; Kohutková Lánová, Martina; Jiráková, Ludmila; Budková, Zuzana; Pacherník, Jiří; Šmarda, Jan; Beneš, Petr

2017-09-01

Neuroblastoma is the most common extracranial solid tumour of infancy. Pathological activation of glucose consumption, glycolysis and glycolysis-activating Akt kinase occur frequently in neuroblastoma cells, and these changes correlate with poor prognosis of patients. Therefore, several inhibitors of glucose utilization and the Akt kinase activity are in preclinical trials as potential anti-cancer drugs. However, metabolic plasticity of cancer cells might undermine efficacy of this approach. In this work, we identified oxidative phosphorylation as compensatory mechanism preserving viability of neuroblastoma cells with inhibited glucose uptake/Akt kinase. It was oxidative phosphorylation that maintained intracellular level of ATP and proliferative capacity of these cells. The oxidative phosphorylation inhibitors (rotenone, tetrathiomolybdate) synergized with inhibitor of the Akt kinase/glucose uptake in down-regulation of both viability of neuroblastoma cells and clonogenic potential of cells forming neuroblastoma spheroids. Interestingly, tetrathiomolybdate acted as highly specific inhibitor of oxygen consumption and activator of lactate production in neuroblastoma cells, but not in normal fibroblasts and neuronal cells. Moreover, the reducing effect of tetrathiomolybdate on cell viability and the level of ATP in the cells with inhibited Akt kinase/glucose uptake was also selective for neuroblastoma cells. Therefore, efficient elimination of neuroblastoma cells requires inhibition of both glucose uptake/Akt kinase and oxidative phosphorylation activities. The use of tetrathiomolybdate as a mitochondrial inhibitor contributes to selectivity of this combined treatment, preferentially targeting neuroblastoma cells. © 2017 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

Design of inhibitors of thymidylate kinase from Variola virus as new selective drugs against smallpox.

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Guimarães, Ana P; de Souza, Felipe R; Oliveira, Aline A; Gonçalves, Arlan S; de Alencastro, Ricardo B; Ramalho, Teodorico C; França, Tanos C C

2015-02-16

Recently we constructed a homology model of the enzyme thymidylate kinase from Variola virus (VarTMPK) and proposed it as a new target to the drug design against smallpox. In the present work, we used the antivirals cidofovir and acyclovir as reference compounds to choose eleven compounds as leads to the drug design of inhibitors for VarTMPK. Docking and molecular dynamics (MD) studies of the interactions of these compounds inside VarTMPK and human TMPK (HssTMPK) suggest that they compete for the binding region of the substrate and were used to propose the structures of ten new inhibitors for VarTMPK. Further docking and MD simulations of these compounds, inside VarTMPK and HssTMPK, suggest that nine among ten are potential selective inhibitors of VarTMPK. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

An in silico high-throughput screen identifies potential selective inhibitors for the non-receptor tyrosine kinase Pyk2

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Meirson T

2017-05-01

Full Text Available Tomer Meirson, Abraham O Samson, Hava Gil-Henn Faculty of Medicine in the Galilee, Bar-Ilan University, Safed, Israel Abstract: The non-receptor tyrosine kinase proline-rich tyrosine kinase 2 (Pyk2 is a critical mediator of signaling from cell surface growth factor and adhesion receptors to cell migration, proliferation, and survival. Emerging evidence indicates that signaling by Pyk2 regulates hematopoietic cell response, bone density, neuronal degeneration, angiogenesis, and cancer. These physiological and pathological roles of Pyk2 warrant it as a valuable therapeutic target for invasive cancers, osteoporosis, Alzheimer’s disease, and inflammatory cellular response. Despite its potential as a therapeutic target, no potent and selective inhibitor of Pyk2 is available at present. As a first step toward discovering specific potential inhibitors of Pyk2, we used an in silico high-throughput screening approach. A virtual library of six million lead-like compounds was docked against four different high-resolution Pyk2 kinase domain crystal structures and further selected for predicted potency and ligand efficiency. Ligand selectivity for Pyk2 over focal adhesion kinase (FAK was evaluated by comparative docking of ligands and measurement of binding free energy so as to obtain 40 potential candidates. Finally, the structural flexibility of a subset of the docking complexes was evaluated by molecular dynamics simulation, followed by intermolecular interaction analysis. These compounds may be considered as promising leads for further development of highly selective Pyk2 inhibitors. Keywords: virtual screen, efficiency metrics, MM-GBSA, molecular dynamics

Cellular growth kinetics distinguish a cyclophilin inhibitor from an HSP90 inhibitor as a selective inhibitor of hepatitis C virus.

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Rudolf K F Beran

Full Text Available During antiviral drug discovery, it is critical to distinguish molecules that selectively interrupt viral replication from those that reduce virus replication by adversely affecting host cell viability. In this report we investigate the selectivity of inhibitors of the host chaperone proteins cyclophilin A (CypA and heat-shock protein 90 (HSP90 which have each been reported to inhibit replication of hepatitis C virus (HCV. By comparing the toxicity of the HSP90 inhibitor, 17-(Allylamino-17-demethoxygeldanamycin (17-AAG to two known cytostatic compounds, colchicine and gemcitabine, we provide evidence that 17-AAG exerts its antiviral effects indirectly through slowing cell growth. In contrast, a cyclophilin inhibitor, cyclosporin A (CsA, exhibited selective antiviral activity without slowing cell proliferation. Furthermore, we observed that 17-AAG had little antiviral effect in a non-dividing cell-culture model of HCV replication, while CsA reduced HCV titer by more than two orders of magnitude in the same model. The assays we describe here are useful for discriminating selective antivirals from compounds that indirectly affect virus replication by reducing host cell viability or slowing cell growth.

Epitope targeting of tertiary protein structure enables target-guided synthesis of a potent in-cell inhibitor of botulinum neurotoxin.

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Farrow, Blake; Wong, Michelle; Malette, Jacquie; Lai, Bert; Deyle, Kaycie M; Das, Samir; Nag, Arundhati; Agnew, Heather D; Heath, James R

2015-06-08

Botulinum neurotoxin (BoNT) serotype A is the most lethal known toxin and has an occluded structure, which prevents direct inhibition of its active site before it enters the cytosol. Target-guided synthesis by in situ click chemistry is combined with synthetic epitope targeting to exploit the tertiary structure of the BoNT protein as a landscape for assembling a competitive inhibitor. A substrate-mimicking peptide macrocycle is used as a direct inhibitor of BoNT. An epitope-targeting in situ click screen is utilized to identify a second peptide macrocycle ligand that binds to an epitope that, in the folded BoNT structure, is active-site-adjacent. A second in situ click screen identifies a molecular bridge between the two macrocycles. The resulting divalent inhibitor exhibits an in vitro inhibition constant of 165 pM against the BoNT/A catalytic chain. The inhibitor is carried into cells by the intact holotoxin, and demonstrates protection and rescue of BoNT intoxication in a human neuron model. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Burglar Target Selection

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Townsley, Michael; Bernasco, Wim; Ruiter, Stijn; Johnson, Shane D.; White, Gentry; Baum, Scott

2015-01-01

Objectives: This study builds on research undertaken by Bernasco and Nieuwbeerta and explores the generalizability of a theoretically derived offender target selection model in three cross-national study regions. Methods: Taking a discrete spatial choice approach, we estimate the impact of both environment- and offender-level factors on residential burglary placement in the Netherlands, the United Kingdom, and Australia. Combining cleared burglary data from all study regions in a single statistical model, we make statistical comparisons between environments. Results: In all three study regions, the likelihood an offender selects an area for burglary is positively influenced by proximity to their home, the proportion of easily accessible targets, and the total number of targets available. Furthermore, in two of the three study regions, juvenile offenders under the legal driving age are significantly more influenced by target proximity than adult offenders. Post hoc tests indicate the magnitudes of these impacts vary significantly between study regions. Conclusions: While burglary target selection strategies are consistent with opportunity-based explanations of offending, the impact of environmental context is significant. As such, the approach undertaken in combining observations from multiple study regions may aid criminology scholars in assessing the generalizability of observed findings across multiple environments. PMID:25866418

Selective Inhibition of Histone Deacetylation in Melanoma Increases Targeted Gene Delivery by a Bacteriophage Viral Vector

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Samuel Campbell

2018-04-01

Full Text Available The previously developed adeno-associated virus/phage (AAVP vector, a hybrid between M13 bacteriophage (phage viruses that infect bacteria only and human Adeno-Associated Virus (AAV, is a promising tool in targeted gene therapy against cancer. AAVP can be administered systemically and made tissue specific through the use of ligand-directed targeting. Cancer cells and tumor-associated blood vessels overexpress the αν integrin receptors, which are involved in tumor angiogenesis and tumor invasion. AAVP is targeted to these integrins via a double cyclic RGD4C ligand displayed on the phage capsid. Nevertheless, there remain significant host-defense hurdles to the use of AAVP in targeted gene delivery and subsequently in gene therapy. We previously reported that histone deacetylation in cancer constitutes a barrier to AAVP. Herein, to improve AAVP-mediated gene delivery to cancer cells, we combined the vector with selective adjuvant chemicals that inhibit specific histone deacetylases (HDAC. We examined the effects of the HDAC inhibitor C1A that mainly targets HDAC6 and compared this to sodium butyrate, a pan-HDAC inhibitor with broad spectrum HDAC inhibition. We tested the effects on melanoma, known for HDAC6 up-regulation, and compared this side by side with a normal human kidney HEK293 cell line. Varying concentrations were tested to determine cytotoxic levels as well as effects on AAVP gene delivery. We report that the HDAC inhibitor C1A increased AAVP-mediated transgene expression by up to ~9-fold. These findings indicate that selective HDAC inhibition is a promising adjuvant treatment for increasing the therapeutic value of AAVP.

Homology modeling of parasite histone deacetylases to guide the structure-based design of selective inhibitors.

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Melesina, Jelena; Robaa, Dina; Pierce, Raymond J; Romier, Christophe; Sippl, Wolfgang

2015-11-01

Histone deacetylases (HDACs) are promising epigenetic targets for the treatment of various diseases, including cancer and neurodegenerative disorders. There is evidence that they can also be addressed to treat parasitic infections. Recently, the first X-ray structure of a parasite HDAC was published, Schistosoma mansoni HDAC8, giving structural insights into its inhibition. However, most of the targets from parasites of interest still lack this structural information. Therefore, we prepared homology models of relevant parasitic HDACs and compared them to human and S. mansoni HDACs. The information about known S. mansoni HDAC8 inhibitors and compounds that affect the growth of Trypanosoma, Leishmania and Plasmodium species was used to validate the models by docking and molecular dynamics studies. Our results provide analysis of structural features of parasitic HDACs and should be helpful for selecting promising candidates for biological testing and for structure-based optimisation of parasite-specific inhibitors. Copyright © 2015 Elsevier Inc. All rights reserved.

Discovery of Highly Selective and Nanomolar Carbamate-Based Butyrylcholinesterase Inhibitors by Rational Investigation into Their Inhibition Mode.

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Sawatzky, Edgar; Wehle, Sarah; Kling, Beata; Wendrich, Jan; Bringmann, Gerhard; Sotriffer, Christoph A; Heilmann, Jörg; Decker, Michael

2016-03-10

Butyrylcholinesterase (BChE) is a promising target for the treatment of later stage cognitive decline in Alzheimer's disease. A set of pseudo-irreversible BChE inhibitors with high selectivity over hAChE was synthesized based on carbamates attached to tetrahydroquinazoline scaffolds with the 2-thiophenyl compound 2p as the most potent inhibitor of eqBChE (KC = 14.3 nM) and also of hBChE (KC = 19.7 nM). The inhibitors transfer the carbamate moiety onto the active site under release of the phenolic tetrahydroquinazoline scaffolds that themselves act as neuroprotectants. By combination of kinetic data with molecular docking studies, a plausible binding model was probed describing how the tetrahydroquinazoline scaffold guides the carbamate into a close position to the active site. The model explains the influence of the carrier scaffold onto the affinity of an inhibitor just before carbamate transfer. This strategy can be used to utilize the binding mode of other carbamate-based inhibitors.

Insight into the Selectivity of the G7-18NATE Inhibitor Peptide for the Grb7-SH2 Domain Target.

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Watson, Gabrielle M; Lucas, William A H; Gunzburg, Menachem J; Wilce, Jacqueline A

2017-01-01

Growth factor receptor bound protein 7 (Grb7) is an adaptor protein with established roles in the progression of both breast and pancreatic cancers. Through its C-terminal SH2 domain, Grb7 binds to phosphorylated tyrosine kinases to promote proliferative and migratory signaling. Here, we investigated the molecular basis for the specificity of a Grb7 SH2-domain targeted peptide inhibitor. We identified that arginine 462 in the BC loop is unique to Grb7 compared to Grb2, another SH2 domain bearing protein that shares the same consensus binding motif as Grb7. Using surface plasmon resonance we demonstrated that Grb7-SH2 binding to G7-18NATE is reduced 3.3-fold when the arginine is mutated to the corresponding Grb2 amino acid. The reverse mutation in Grb2-SH2 (serine to arginine), however, was insufficient to restore binding of G7-18NATE to Grb2-SH2. Further, using a microarray, we confirmed that G7-18NATE is specific for Grb7 over a panel of 79 SH2 domains, and identified that leucine at the βD6 position may also be a requirement for Grb7-SH2 binding. This study provides insight into the specificity defining features of Grb7 for the inhibitor molecule G7-18NATE, that will assist in the development of improved Grb7 targeted inhibitors.

Insight into the Selectivity of the G7-18NATE Inhibitor Peptide for the Grb7-SH2 Domain Target

Directory of Open Access Journals (Sweden)

Gabrielle M. Watson

2017-09-01

Full Text Available Growth factor receptor bound protein 7 (Grb7 is an adaptor protein with established roles in the progression of both breast and pancreatic cancers. Through its C-terminal SH2 domain, Grb7 binds to phosphorylated tyrosine kinases to promote proliferative and migratory signaling. Here, we investigated the molecular basis for the specificity of a Grb7 SH2-domain targeted peptide inhibitor. We identified that arginine 462 in the BC loop is unique to Grb7 compared to Grb2, another SH2 domain bearing protein that shares the same consensus binding motif as Grb7. Using surface plasmon resonance we demonstrated that Grb7-SH2 binding to G7-18NATE is reduced 3.3-fold when the arginine is mutated to the corresponding Grb2 amino acid. The reverse mutation in Grb2-SH2 (serine to arginine, however, was insufficient to restore binding of G7-18NATE to Grb2-SH2. Further, using a microarray, we confirmed that G7-18NATE is specific for Grb7 over a panel of 79 SH2 domains, and identified that leucine at the βD6 position may also be a requirement for Grb7-SH2 binding. This study provides insight into the specificity defining features of Grb7 for the inhibitor molecule G7-18NATE, that will assist in the development of improved Grb7 targeted inhibitors.

Insight into the Selectivity of the G7-18NATE Inhibitor Peptide for the Grb7-SH2 Domain Target

Science.gov (United States)

Watson, Gabrielle M.; Lucas, William A. H.; Gunzburg, Menachem J.; Wilce, Jacqueline A.

2017-01-01

Growth factor receptor bound protein 7 (Grb7) is an adaptor protein with established roles in the progression of both breast and pancreatic cancers. Through its C-terminal SH2 domain, Grb7 binds to phosphorylated tyrosine kinases to promote proliferative and migratory signaling. Here, we investigated the molecular basis for the specificity of a Grb7 SH2-domain targeted peptide inhibitor. We identified that arginine 462 in the BC loop is unique to Grb7 compared to Grb2, another SH2 domain bearing protein that shares the same consensus binding motif as Grb7. Using surface plasmon resonance we demonstrated that Grb7-SH2 binding to G7-18NATE is reduced 3.3-fold when the arginine is mutated to the corresponding Grb2 amino acid. The reverse mutation in Grb2-SH2 (serine to arginine), however, was insufficient to restore binding of G7-18NATE to Grb2-SH2. Further, using a microarray, we confirmed that G7-18NATE is specific for Grb7 over a panel of 79 SH2 domains, and identified that leucine at the βD6 position may also be a requirement for Grb7-SH2 binding. This study provides insight into the specificity defining features of Grb7 for the inhibitor molecule G7-18NATE, that will assist in the development of improved Grb7 targeted inhibitors. PMID:29018805

Tofacitinib and analogs as inhibitors of the histone kinase PRK1 (PKN1).

Science.gov (United States)

Ostrovskyi, Dmytro; Rumpf, Tobias; Eib, Julia; Lumbroso, Alexandre; Slynko, Inna; Klaeger, Susan; Heinzlmeir, Stephanie; Forster, Michael; Gehringer, Matthias; Pfaffenrot, Ellen; Bauer, Silke Mona; Schmidtkunz, Karin; Wenzler, Sandra; Metzger, Eric; Kuster, Bernhard; Laufer, Stefan; Schüle, Roland; Sippl, Wolfgang; Breit, Bernhard; Jung, Manfred

2016-09-01

The histone kinase PRK1 has been identified as a potential target to combat prostate cancer but selective PRK1 inhibitors are lacking. The US FDA -approved JAK1-3 inhibitor tofacitinib also potently inhibits PRK1 in vitro. We show that tofacitinib also inhibits PRK1 in a cellular setting. Using tofacitinib as a starting point for structure-activity relationship studies, we identified a more potent and another more selective PRK1 inhibitor compared with tofacitinib. Furthermore, we found two potential PRK1/JAK3-selectivity hotspots. The identified inhibitors and the selectivity hotspots lay the basis for the development of selective PRK1 inhibitors. The identification of PRK1, but also of other cellular tofacitinib targets, has implications on its clinical use and on future development of tofacitinib-like JAK inhibitors. [Formula: see text].

Identification of selective inhibitors of RET and comparison with current clinical candidates through development and validation of a robust screening cascade [version 1; referees: 2 approved

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Amanda J. Watson

2016-05-01

Full Text Available RET (REarranged during Transfection is a receptor tyrosine kinase, which plays pivotal roles in regulating cell survival, differentiation, proliferation, migration and chemotaxis. Activation of RET is a mechanism of oncogenesis in medullary thyroid carcinomas where both germline and sporadic activating somatic mutations are prevalent.   At present, there are no known specific RET inhibitors in clinical development, although many potent inhibitors of RET have been opportunistically identified through selectivity profiling of compounds initially designed to target other tyrosine kinases. Vandetanib and cabozantinib, both multi-kinase inhibitors with RET activity, are approved for use in medullary thyroid carcinoma, but additional pharmacological activities, most notably inhibition of vascular endothelial growth factor - VEGFR2 (KDR, lead to dose-limiting toxicity. The recent identification of RET fusions present in ~1% of lung adenocarcinoma patients has renewed interest in the identification and development of more selective RET inhibitors lacking the toxicities associated with the current treatments.   In an earlier publication [Newton et al, 2016; 1] we reported the discovery of a series of 2-substituted phenol quinazolines as potent and selective RET kinase inhibitors. Here we describe the development of the robust screening cascade which allowed the identification and advancement of this chemical series.  Furthermore we have profiled a panel of RET-active clinical compounds both to validate the cascade and to confirm that none display a RET-selective target profile.

Discovery of Novel Tricyclic Heterocycles as Potent and Selective DPP-4 Inhibitors for the Treatment of Type 2 Diabetes

Energy Technology Data Exchange (ETDEWEB)

Wu, Wen-Lian; Hao, Jinsong; Domalski, Martin; Burnett, Duane A.; Pissarnitski, Dmitri; Zhao, Zhiqiang; Stamford, Andrew; Scapin, Giovanna; Gao, Ying-Duo; Soriano, Aileen; Kelly, Terri M.; Yao, Zuliang; Powles, Mary Ann; Chen, Shiying; Mei, Hong; Hwa, Joyce (Merck)

2016-05-12

In our efforts to develop second generation DPP-4 inhibitors, we endeavored to identify distinct structures with long-acting (once weekly) potential. Taking advantage of X-ray cocrystal structures of sitagliptin and other DPP-4 inhibitors, such as alogliptin and linagliptin bound to DPP-4, and aided by molecular modeling, we designed several series of heterocyclic compounds as initial targets. During their synthesis, an unexpected chemical transformation provided a novel tricyclic scaffold that was beyond our original design. Capitalizing on this serendipitous discovery, we have elaborated this scaffold into a very potent and selective DPP-4 inhibitor lead series, as highlighted by compound 17c.

Small-molecule kinase inhibitors: an analysis of FDA-approved drugs

DEFF Research Database (Denmark)

Wu, Peng; Nielsen, Thomas Eiland; Clausen, Mads Hartvig

2016-01-01

Small-molecule kinase inhibitors (SMKIs), 28 of which are approved by the US Food and Drug Administration (FDA), have been actively pursued as promising targeted therapeutics. Here, we assess the key structural and physicochemical properties, target selectivity and mechanism of function, and ther......Small-molecule kinase inhibitors (SMKIs), 28 of which are approved by the US Food and Drug Administration (FDA), have been actively pursued as promising targeted therapeutics. Here, we assess the key structural and physicochemical properties, target selectivity and mechanism of function...

SAH derived potent and selective EZH2 inhibitors

Energy Technology Data Exchange (ETDEWEB)

Kung, Pei-Pei; Huang, Buwen; Zehnder, Luke; Tatlock, John; Bingham, Patrick; Krivacic, Cody; Gajiwala, Ketan; Diehl, Wade; Yu, Xiu; Maegley, Karen A.

2015-04-01

A series of novel enhancer of zeste homolog 2 (EZH2) inhibitors was designed based on the chemical structure of the histone methyltransferase (HMT) inhibitor SAH (S-adenosyl-l-homocysteine). These nucleoside-based EZH2 inhibitors blocked the methylation of nucleosomes at H3K27 in biochemical assays employing both WT PRC2 complex as well as a Y641N mutant PRC2 complex. The most potent compound, 27, displayed IC50’s against both complexes of 270 nM and 70 nM, respectively. To our knowledge, compound 27 is the most potent SAH-derived inhibitor of the EZH2 PRC2 complex yet identified. This compound also displayed improved potency, lipophilic efficiency (LipE), and selectivity profile against other lysine methyltransferases compared with SAH.

Discovery of PF-04620110, a Potent, Selective, and Orally Bioavailable Inhibitor of DGAT-1.

Science.gov (United States)

Dow, Robert L; Li, Jian-Cheng; Pence, Michael P; Gibbs, E Michael; LaPerle, Jennifer L; Litchfield, John; Piotrowski, David W; Munchhof, Michael J; Manion, Tara B; Zavadoski, William J; Walker, Gregory S; McPherson, R Kirk; Tapley, Susan; Sugarman, Eliot; Guzman-Perez, Angel; DaSilva-Jardine, Paul

2011-05-12

Acyl-CoA:diacylglycerol acyltransferase-1 (DGAT-1) catalyzes the final committed step in the biosynthesis of triglycerides. DGAT-1 knockout mice have been shown to be resistant to diet-induced obesity and have increased insulin sensitivity. Thus, inhibition of DGAT-1 may represent an attractive target for the treatment of obesity or type II diabetes. Herein, we report the discovery and characterization of a potent and selective DGAT-1 inhibitor PF-04620110 (3). Compound 3 inhibits DGAT-1 with an IC50 of 19 nM and shows high selectivity versus a broad panel of off-target pharmacologic end points. In vivo DGAT-1 inhibition has been demonstrated through reduction of plasma triglyceride levels in rodents at doses of ≥0.1 mg/kg following a lipid challenge. On the basis of this pharmacologic and pharmacokinetic profile, compound 3 has been advanced to human clinical studies.

A dual-color fluorescence-based platform to identify selective inhibitors of Akt signaling.

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Aranzazú Rosado

Full Text Available BACKGROUND: Inhibition of Akt signaling is considered one of the most promising therapeutic strategies for many cancers. However, rational target-orientated approaches to cell based drug screens for anti-cancer agents have historically been compromised by the notorious absence of suitable control cells. METHODOLOGY/PRINCIPAL FINDINGS: In order to address this fundamental problem, we have developed BaFiso, a live-cell screening platform to identify specific inhibitors of this pathway. BaFiso relies on the co-culture of isogenic cell lines that have been engineered to sustain interleukin-3 independent survival of the parental Ba/F3 cells, and that are individually tagged with different fluorescent proteins. Whilst in the first of these two lines cell survival in the absence of IL-3 is dependent on the expression of activated Akt, the cells expressing constitutively-activated Stat5 signaling display IL-3 independent growth and survival in an Akt-independent manner. Small molecules can then be screened in these lines to identify inhibitors that rescue IL-3 dependence. CONCLUSIONS/SIGNIFICANCE: BaFiso measures differential cell survival using multiparametric live cell imaging and permits selective inhibitors of Akt signaling to be identified. BaFiso is a platform technology suitable for the identification of small molecule inhibitors of IL-3 mediated survival signaling.

Discovery and characterization of a potent and selective inhibitor of Aedes aegypti inward rectifier potassium channels.

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Rene Raphemot

Full Text Available Vector-borne diseases such as dengue fever and malaria, which are transmitted by infected female mosquitoes, affect nearly half of the world's population. The emergence of insecticide-resistant mosquito populations is reducing the effectiveness of conventional insecticides and threatening current vector control strategies, which has created an urgent need to identify new molecular targets against which novel classes of insecticides can be developed. We previously demonstrated that small molecule inhibitors of mammalian Kir channels represent promising chemicals for new mosquitocide development. In this study, high-throughput screening of approximately 30,000 chemically diverse small-molecules was employed to discover potent and selective inhibitors of Aedes aegypti Kir1 (AeKir1 channels heterologously expressed in HEK293 cells. Of 283 confirmed screening 'hits', the small-molecule inhibitor VU625 was selected for lead optimization and in vivo studies based on its potency and selectivity toward AeKir1, and tractability for medicinal chemistry. In patch clamp electrophysiology experiments of HEK293 cells, VU625 inhibits AeKir1 with an IC50 value of 96.8 nM, making VU625 the most potent inhibitor of AeKir1 described to date. Furthermore, electrophysiology experiments in Xenopus oocytes revealed that VU625 is a weak inhibitor of AeKir2B. Surprisingly, injection of VU625 failed to elicit significant effects on mosquito behavior, urine excretion, or survival. However, when co-injected with probenecid, VU625 inhibited the excretory capacity of mosquitoes and was toxic, suggesting that the compound is a substrate of organic anion and/or ATP-binding cassette (ABC transporters. The dose-toxicity relationship of VU625 (when co-injected with probenecid is biphasic, which is consistent with the molecule inhibiting both AeKir1 and AeKir2B with different potencies. This study demonstrates proof-of-concept that potent and highly selective inhibitors of mosquito

Discovery of a highly selective chemical inhibitor of matrix metalloproteinase-9 (MMP-9) that allosterically inhibits zymogen activation.

Science.gov (United States)

Scannevin, Robert H; Alexander, Richard; Haarlander, Tara Mezzasalma; Burke, Sharon L; Singer, Monica; Huo, Cuifen; Zhang, Yue-Mei; Maguire, Diane; Spurlino, John; Deckman, Ingrid; Carroll, Karen I; Lewandowski, Frank; Devine, Eric; Dzordzorme, Keli; Tounge, Brett; Milligan, Cindy; Bayoumy, Shariff; Williams, Robyn; Schalk-Hihi, Celine; Leonard, Kristi; Jackson, Paul; Todd, Matthew; Kuo, Lawrence C; Rhodes, Kenneth J

2017-10-27

Aberrant activation of matrix metalloproteinases (MMPs) is a common feature of pathological cascades observed in diverse disorders, such as cancer, fibrosis, immune dysregulation, and neurodegenerative diseases. MMP-9, in particular, is highly dynamically regulated in several pathological processes. Development of MMP inhibitors has therefore been an attractive strategy for therapeutic intervention. However, a long history of failed clinical trials has demonstrated that broad-spectrum MMP inhibitors have limited clinical utility, which has spurred the development of inhibitors selective for individual MMPs. Attaining selectivity has been technically challenging because of sequence and structural conservation across the various MMPs. Here, through a biochemical and structural screening paradigm, we have identified JNJ0966, a highly selective compound that inhibited activation of MMP-9 zymogen and subsequent generation of catalytically active enzyme. JNJ0966 had no effect on MMP-1, MMP-2, MMP-3, MMP-9, or MMP-14 catalytic activity and did not inhibit activation of the highly related MMP-2 zymogen. The molecular basis for this activity was characterized as an interaction of JNJ0966 with a structural pocket in proximity to the MMP-9 zymogen cleavage site near Arg-106, which is distinct from the catalytic domain. JNJ0966 was efficacious in reducing disease severity in a mouse experimental autoimmune encephalomyelitis model, demonstrating the viability of this therapeutic approach. This discovery reveals an unprecedented pharmacological approach to MMP inhibition, providing an opportunity to improve selectivity of future clinical drug candidates. Targeting zymogen activation in this manner may also allow for pharmaceutical exploration of other enzymes previously viewed as intractable drug targets. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Selective Targeting of CTNBB1-, KRAS- or MYC-Driven Cell Growth by Combinations of Existing Drugs.

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Joost C M Uitdehaag

Full Text Available The aim of combination drug treatment in cancer therapy is to improve response rate and to decrease the probability of the development of drug resistance. Preferably, drug combinations are synergistic rather than additive, and, ideally, drug combinations work synergistically only in cancer cells and not in non-malignant cells. We have developed a workflow to identify such targeted synergies, and applied this approach to selectively inhibit the proliferation of cell lines with mutations in genes that are difficult to modulate with small molecules. The approach is based on curve shift analysis, which we demonstrate is a more robust method of determining synergy than combination matrix screening with Bliss-scoring. We show that the MEK inhibitor trametinib is more synergistic in combination with the BRAF inhibitor dabrafenib than with vemurafenib, another BRAF inhibitor. In addition, we show that the combination of MEK and BRAF inhibitors is synergistic in BRAF-mutant melanoma cells, and additive or antagonistic in, respectively, BRAF-wild type melanoma cells and non-malignant fibroblasts. This combination exemplifies that synergistic action of drugs can depend on cancer genotype. Next, we used curve shift analysis to identify new drug combinations that specifically inhibit cancer cell proliferation driven by difficult-to-drug cancer genes. Combination studies were performed with compounds that as single agents showed preference for inhibition of cancer cells with mutations in either the CTNNB1 gene (coding for β-catenin, KRAS, or cancer cells expressing increased copy numbers of MYC. We demonstrate that the Wnt-pathway inhibitor ICG-001 and trametinib acted synergistically in Wnt-pathway-mutant cell lines. The ERBB2 inhibitor TAK-165 was synergistic with trametinib in KRAS-mutant cell lines. The EGFR/ERBB2 inhibitor neratinib acted synergistically with the spindle poison docetaxel and with the Aurora kinase inhibitor GSK-1070916 in cell lines

Selective Targeting of CTNNB1-, KRAS- or MYC-Driven Cell Growth by Combinations of Existing Drugs

Science.gov (United States)

Uitdehaag, Joost C. M.; de Roos, Jeroen A. D. M.; van Doornmalen, Antoon M.; Prinsen, Martine B. W.; Spijkers-Hagelstein, Jill A. P.; de Vetter, Judith R. F.; de Man, Jos; Buijsman, Rogier C.; Zaman, Guido J. R.

2015-01-01

The aim of combination drug treatment in cancer therapy is to improve response rate and to decrease the probability of the development of drug resistance. Preferably, drug combinations are synergistic rather than additive, and, ideally, drug combinations work synergistically only in cancer cells and not in non-malignant cells. We have developed a workflow to identify such targeted synergies, and applied this approach to selectively inhibit the proliferation of cell lines with mutations in genes that are difficult to modulate with small molecules. The approach is based on curve shift analysis, which we demonstrate is a more robust method of determining synergy than combination matrix screening with Bliss-scoring. We show that the MEK inhibitor trametinib is more synergistic in combination with the BRAF inhibitor dabrafenib than with vemurafenib, another BRAF inhibitor. In addition, we show that the combination of MEK and BRAF inhibitors is synergistic in BRAF-mutant melanoma cells, and additive or antagonistic in, respectively, BRAF-wild type melanoma cells and non-malignant fibroblasts. This combination exemplifies that synergistic action of drugs can depend on cancer genotype. Next, we used curve shift analysis to identify new drug combinations that specifically inhibit cancer cell proliferation driven by difficult-to-drug cancer genes. Combination studies were performed with compounds that as single agents showed preference for inhibition of cancer cells with mutations in either the CTNNB1 gene (coding for β-catenin), KRAS, or cancer cells expressing increased copy numbers of MYC. We demonstrate that the Wnt-pathway inhibitor ICG-001 and trametinib acted synergistically in Wnt-pathway-mutant cell lines. The ERBB2 inhibitor TAK-165 was synergistic with trametinib in KRAS-mutant cell lines. The EGFR/ERBB2 inhibitor neratinib acted synergistically with the spindle poison docetaxel and with the Aurora kinase inhibitor GSK-1070916 in cell lines with MYC amplification

QStatin, a Selective Inhibitor of Quorum Sensing in Vibrio Species.

Science.gov (United States)

Kim, Byoung Sik; Jang, Song Yee; Bang, Ye-Ji; Hwang, Jungwon; Koo, Youngwon; Jang, Kyung Ku; Lim, Dongyeol; Kim, Myung Hee; Choi, Sang Ho

2018-01-30

Pathogenic Vibrio species cause diseases in diverse marine animals reared in aquaculture. Since their pathogenesis, persistence, and survival in marine environments are regulated by quorum sensing (QS), QS interference has attracted attention as a means to control these bacteria in aquatic settings. A few QS inhibitors of Vibrio species have been reported, but detailed molecular mechanisms are lacking. Here, we identified a novel, potent, and selective Vibrio QS inhibitor, named QStatin [1-(5-bromothiophene-2-sulfonyl)-1H-pyrazole], which affects Vibrio harveyi LuxR homologues, the well-conserved master transcriptional regulators for QS in Vibrio species. Crystallographic and biochemical analyses showed that QStatin binds tightly to a putative ligand-binding pocket in SmcR, the LuxR homologue in V. vulnificus , and changes the flexibility of the protein, thereby altering its transcription regulatory activity. Transcriptome analysis revealed that QStatin results in SmcR dysfunction, affecting the expression of SmcR regulon required for virulence, motility/chemotaxis, and biofilm dynamics. Notably, QStatin attenuated representative QS-regulated phenotypes in various Vibrio species, including virulence against the brine shrimp ( Artemia franciscana ). Together, these results provide molecular insights into the mechanism of action of an effective, sustainable QS inhibitor that is less susceptible to resistance than other antimicrobial agents and useful in controlling the virulence of Vibrio species in aquacultures. IMPORTANCE Yields of aquaculture, such as penaeid shrimp hatcheries, are greatly affected by vibriosis, a disease caused by pathogenic Vibrio infections. Since bacterial cell-to-cell communication, known as quorum sensing (QS), regulates pathogenesis of Vibrio species in marine environments, QS inhibitors have attracted attention as alternatives to conventional antibiotics in aquatic settings. Here, we used target-based high-throughput screening to identify

Second Generation Grp94-Selective Inhibitors Provide Opportunities for the Inhibition of Metastatic Cancer

Energy Technology Data Exchange (ETDEWEB)

Crowley, Vincent M. [Department of Medicinal Chemistry, The University of Kansas, 1251 Wescoe Hall Dr. Malott 4070 Lawrence KS 66045 USA; Huard, Dustin J. E. [School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta GA 30332 USA; Lieberman, Raquel L. [School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta GA 30332 USA; Blagg, Brian S. J. [Warren Family Research Center for Drug Discovery and Development, and Department of Chemistry & Biochemistry, University of Notre Dame, 305 McCourtney Hall Notre Dame IN 46556 USA

2017-09-27

Glucose regulated protein 94 (Grp94) is the endoplasmic reticulum (ER) resident isoform of the 90 kDa heat shock protein (Hsp90) family and its inhibition represents a promising therapeutic target for the treatment of many diseases. Modification of the first generation cis-amide bioisostere imidazole to alter the angle between the resorcinol ring and the benzyl side chain via cis-amide replacements produced compounds with improved Grp94 affinity and selectivity. Structure–activity relationship studies led to the discovery of compound 30, which exhibits 540 nm affinity and 73-fold selectivity towards Grp94. Grp94 is responsible for the maturation and trafficking of proteins associated with cell signaling and motility, including select integrins. The Grp94-selective inhibitor 30 was shown to exhibit potent anti-migratory effects against multiple aggressive and metastatic cancers.

A Potent and Selective Quinoxalinone-Based STK33 Inhibitor Does Not Show Synthetic Lethality in KRAS-Dependent Cells

Science.gov (United States)

2012-01-01

The KRAS oncogene is found in up to 30% of all human tumors. In 2009, RNAi experiments revealed that lowering mRNA levels of a transcript encoding the serine/threonine kinase STK33 was selectively toxic to KRAS-dependent cancer cell lines, suggesting that small-molecule inhibitors of STK33 might selectively target KRAS-dependent cancers. To test this hypothesis, we initiated a high-throughput screen using compounds in the Molecular Libraries Small Molecule Repository (MLSMR). Several hits were identified, and one of these, a quinoxalinone derivative, was optimized. Extensive SAR studies were performed and led to the chemical probe ML281 that showed low nanomolar inhibition of purified recombinant STK33 and a distinct selectivity profile as compared to other STK33 inhibitors that were reported in the course of these studies. Even at the highest concentration tested (10 μM), ML281 had no effect on the viability of KRAS-dependent cancer cells. These results are consistent with other recent reports using small-molecule STK33 inhibitors. Small molecules having different chemical structures and kinase-selectivity profiles are needed to fully understand the role of STK33 in KRAS-dependent cancers. In this regard, ML281 is a valuable addition to small-molecule probes of STK33. PMID:23256033

Discovery of novel, high potent, ABC type PTP1B inhibitors with TCPTP selectivity and cellular activity.

Science.gov (United States)

Liu, Peihong; Du, Yongli; Song, Lianhua; Shen, Jingkang; Li, Qunyi

2016-08-08

Protein tyrosine phosphatase 1B (PTP1B) as a key negative regulator of both insulin and leptin receptor pathways has been an attractive therapeutic target for the treatment of type 2 diabetes mellitus (T2DM) and obesity. With the goal of enhancing potency and selectivity of the PTP1B inhibitors, a series of methyl salicylate derivatives as ABC type PTP1B inhibitors (P1-P7) were discovered. More importantly, compound P6 exhibited high potent inhibitory activity (IC50 = 50 nM) for PTP1B with 15-fold selectivity over T-cell PTPase (TCPTP). Further studies on cellular activities revealed that compound P6 could enhance insulin-mediated insulin receptor β (IRβ) phosphorylation and insulin-stimulated glucose uptake. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Fuzzy target selection using RFM variables

NARCIS (Netherlands)

Kaymak, U.

2001-01-01

An important data mining problem from the world of direct marketing is target selection. The main task in target selection is the determination of potential customers for a product from a client database. Target selection algorithms identify the profiles of customer groups for a particular product,

Diverse modes of binding in structures of Leishmania majorN-myristoyltransferase with selective inhibitors

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James A. Brannigan

2014-07-01

Full Text Available The leishmaniases are a spectrum of global diseases of poverty associated with immune dysfunction and are the cause of high morbidity. Despite the long history of these diseases, no effective vaccine is available and the currently used drugs are variously compromised by moderate efficacy, complex side effects and the emergence of resistance. It is therefore widely accepted that new therapies are needed. N-Myristoyltransferase (NMT has been validated pre-clinically as a target for the treatment of fungal and parasitic infections. In a previously reported high-throughput screening program, a number of hit compounds with activity against NMT from Leishmania donovani have been identified. Here, high-resolution crystal structures of representative compounds from four hit series in ternary complexes with myristoyl-CoA and NMT from the closely related L. major are reported. The structures reveal that the inhibitors associate with the peptide-binding groove at a site adjacent to the bound myristoyl-CoA and the catalytic α-carboxylate of Leu421. Each inhibitor makes extensive apolar contacts as well as a small number of polar contacts with the protein. Remarkably, the compounds exploit different features of the peptide-binding groove and collectively occupy a substantial volume of this pocket, suggesting that there is potential for the design of chimaeric inhibitors with significantly enhanced binding. Despite the high conservation of the active sites of the parasite and human NMTs, the inhibitors act selectively over the host enzyme. The role of conformational flexibility in the side chain of Tyr217 in conferring selectivity is discussed.

ETORICOXIB IS A NEW SELECTIVE CYCLOOXYGENASE-2 INHIBITOR

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A E Karateev

2009-01-01

Full Text Available The paper provides the clinical characteristics of etoricoxib (Arcoxia, a new selective cyclooxygenase-2 inhibitor having unique properties, which permits it to be distinguished among other nonsteroidal anti-inflammatory agents.

ETORICOXIB IS A NEW SELECTIVE CYCLOOXYGENASE-2 INHIBITOR

Directory of Open Access Journals (Sweden)

A E Karateev

2009-06-01

Full Text Available The paper provides the clinical characteristics of etoricoxib (Arcoxia, a new selective cyclooxygenase-2 inhibitor having unique properties, which permits it to be distinguished among other nonsteroidal anti-inflammatory agents.

Quantification of gamma-secretase modulation differentiates inhibitor compound selectivity between two substrates Notch and amyloid precursor protein

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Yang Ting

2008-11-01

Full Text Available Abstract Background Deposition of amyloid-β protein (Aβ is a major pathological hallmark of Alzheimer's disease (AD. Aβ is generated from γ-secretase cleavage of amyloid precursor protein (APP. In addition to APP, γ-secretase also cleaves other type I integral membrane proteins, including the Notch receptor, a key molecule involved in embryonic development. Results To explore selective γ-secretase inhibitors, a combination of five methods was used to systematically determine these inhibitors' profiles on the γ-secretase cleavage of APP and Notch. When two potent γ-secretase inhibitors, compound E (cpd E and DAPT, were used in a conventional in vitro γ-secretase activity assay, cpd E completely blocked Aβ generation from the cleavage of substrate APP C100, but only had a minor effect on Notch cleavage and NICD generation. Next, cpd E and DAPT were applied to HEK293 cells expressing a truncated Notch substrate NotchΔE. Both cpd E and DAPT were more potent in blocking Aβ generation than NICD generation. Third, a reporter construct was created that carried the NICD targeting promoter with three Su(H binding sequences followed by the luciferase gene. We found that the inhibition of NICD generation by cpd E and DAPT was consistent with the reduced expression of luciferase gene driven by this Notch targeting promoter. Fourth, levels of "Notch-Aβ-like" (Nβ* peptide derived from two previously reported chimeric APP with its transmembrane domain or the juxtamembrane portion replaced by the Notch sequence were quantified. Measurement of Nβ* peptides by ELISA confirmed that EC50's of cpd E were much higher for Nβ* than Aβ. Finally, the expression levels of Notch target gene her6 in cpd E or DAPT-treated zebrafish were correlated with the degree of tail curvature due to defective somitogenesis, a well characterized Notch phenotype in zebrafish. Conclusion Our ELISA-based quantification of Aβ and Nβ* in combination with the test in

Computational-experimental approach to drug-target interaction mapping: A case study on kinase inhibitors.

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Anna Cichonska

2017-08-01

Full Text Available Due to relatively high costs and labor required for experimental profiling of the full target space of chemical compounds, various machine learning models have been proposed as cost-effective means to advance this process in terms of predicting the most potent compound-target interactions for subsequent verification. However, most of the model predictions lack direct experimental validation in the laboratory, making their practical benefits for drug discovery or repurposing applications largely unknown. Here, we therefore introduce and carefully test a systematic computational-experimental framework for the prediction and pre-clinical verification of drug-target interactions using a well-established kernel-based regression algorithm as the prediction model. To evaluate its performance, we first predicted unmeasured binding affinities in a large-scale kinase inhibitor profiling study, and then experimentally tested 100 compound-kinase pairs. The relatively high correlation of 0.77 (p < 0.0001 between the predicted and measured bioactivities supports the potential of the model for filling the experimental gaps in existing compound-target interaction maps. Further, we subjected the model to a more challenging task of predicting target interactions for such a new candidate drug compound that lacks prior binding profile information. As a specific case study, we used tivozanib, an investigational VEGF receptor inhibitor with currently unknown off-target profile. Among 7 kinases with high predicted affinity, we experimentally validated 4 new off-targets of tivozanib, namely the Src-family kinases FRK and FYN A, the non-receptor tyrosine kinase ABL1, and the serine/threonine kinase SLK. Our sub-sequent experimental validation protocol effectively avoids any possible information leakage between the training and validation data, and therefore enables rigorous model validation for practical applications. These results demonstrate that the kernel

Structure-Based Search for New Inhibitors of Cholinesterases

Directory of Open Access Journals (Sweden)

Barbara Malawska

2013-03-01

Full Text Available Cholinesterases are important biological targets responsible for regulation of cholinergic transmission, and their inhibitors are used for the treatment of Alzheimer’s disease. To design new cholinesterase inhibitors, of different structure-based design strategies was followed, including the modification of compounds from a previously developed library and a fragment-based design approach. This led to the selection of heterodimeric structures as potential inhibitors. Synthesis and biological evaluation of selected candidates confirmed that the designed compounds were acetylcholinesterase inhibitors with IC50 values in the mid-nanomolar to low micromolar range, and some of them were also butyrylcholinesterase inhibitors.

Small Molecule Inhibitors That Selectively Block Dengue Virus Methyltransferase*

OpenAIRE

Lim, Siew Pheng; Sonntag, Louis Sebastian; Noble, Christian; Nilar, Shahul H.; Ng, Ru Hui; Zou, Gang; Monaghan, Paul; Chung, Ka Yan; Dong, Hongping; Liu, Boping; Bodenreider, Christophe; Lee, Gladys; Ding, Mei; Chan, Wai Ling; Wang, Gang

2010-01-01

Crystal structure analysis of Flavivirus methyltransferases uncovered a flavivirus-conserved cavity located next to the binding site for its cofactor, S-adenosyl-methionine (SAM). Chemical derivatization of S-adenosyl-homocysteine (SAH), the product inhibitor of the methylation reaction, with substituents that extend into the identified cavity, generated inhibitors that showed improved and selective activity against dengue virus methyltransferase (MTase), but not related human enzymes. Crysta...

Ribociclib (LEE011): Mechanism of Action and Clinical Impact of This Selective Cyclin-Dependent Kinase 4/6 Inhibitor in Various Solid Tumors.

Science.gov (United States)

Tripathy, Debu; Bardia, Aditya; Sellers, William R

2017-07-01

The cyclin D-cyclin-dependent kinase (CDK) 4/6-p16-retinoblastoma (Rb) pathway is commonly disrupted in cancer, leading to abnormal cell proliferation. Therapeutics targeting this pathway have demonstrated antitumor effects in preclinical and clinical studies. Ribociclib is a selective, orally bioavailable inhibitor of CDK4 and CDK6, which received FDA approval in March 2017 and is set to enter the treatment landscape alongside other CDK4/6 inhibitors, including palbociclib and abemaciclib. Here, we describe the mechanism of action of ribociclib and review preclinical and clinical data from phase I, II, and III trials of ribociclib across different tumor types, within the context of other selective CDK4/6 inhibitors. The pharmacokinetics, pharmacodynamics, safety, tolerability, and clinical responses with ribociclib as a single agent or in combination with other therapies are discussed, and an overview of the broad portfolio of ongoing clinical trials with ribociclib across a wide range of indications is presented. On the basis of the available data, ribociclib has a manageable tolerability profile and therapeutic potential for a variety of cancer types. Its high selectivity makes it an important partner drug for other targeted therapies, and it has been shown to enhance the clinical activity of existing anticancer therapies and delay the development of treatment resistance, without markedly increasing toxicity. Ongoing trials of doublet and triplet targeted therapies containing ribociclib seek to identify optimal CDK4/6-based targeted combination regimens for various tumor types and advance the field of precision therapeutics in oncology. Clin Cancer Res; 23(13); 3251-62. ©2017 AACR . ©2017 American Association for Cancer Research.

A possible usage of a CDK4 inhibitor for breast cancer stem cell-targeted therapy

International Nuclear Information System (INIS)

Han, Yu Kyeong; Lee, Jae Ho; Park, Ga-Young; Chun, Sung Hak; Han, Jeong Yun; Kim, Sung Dae; Lee, Janet; Lee, Chang-Woo; Yang, Kwangmo; Lee, Chang Geun

2013-01-01

Highlights: ► A CDK4 inhibitor may be used for breast cancer stem cell-targeted therapy. ► The CDK4 inhibitor differentiated the cancer stem cell population (CD24 − /CD44 + ) of MDA-MB-231. ► The differentiation of the cancer stem cells by the CDK4 inhibitor radiosensitized MDA-MB-231. -- Abstract: Cancer stem cells (CSCs) are one of the main reasons behind cancer recurrence due to their resistance to conventional anti-cancer therapies. Thus, many efforts are being devoted to developing CSC-targeted therapies to overcome the resistance of CSCs to conventional anti-cancer therapies and decrease cancer recurrence. Differentiation therapy is one potential approach to achieve CSC-targeted therapies. This method involves inducing immature cancer cells with stem cell characteristics into more mature or differentiated cancer cells. In this study, we found that a CDK4 inhibitor sensitized MDA-MB-231 cells but not MCF7 cells to irradiation. This difference appeared to be associated with the relative percentage of CSC-population between the two breast cancer cells. The CDK4 inhibitor induced differentiation and reduced the cancer stem cell activity of MDA-MB-231 cells, which are shown by multiple marker or phenotypes of CSCs. Thus, these results suggest that radiosensitization effects may be caused by reducing the CSC-population of MDA-MB-231 through the use of the CDK4 inhibitor. Thus, further investigations into the possible application of the CDK4 inhibitor for CSC-targeted therapy should be performed to enhance the efficacy of radiotherapy for breast cancer

Potent and Selective Covalent Quinazoline Inhibitors of KRAS G12C

Energy Technology Data Exchange (ETDEWEB)

Zeng, Mei; Lu, Jia; Li, Lianbo; Feru, Frederic; Quan, Chunshan; Gero, Thomas W.; Ficarro, Scott B.; Xiong, Yuan; Ambrogio, Chiara; Paranal, Raymond M.; Catalano, Marco; Shao, Jay; Wong, Kwok-Kin; Marto, Jarrod A.; Fischer, Eric S.; Jänne, Pasi A.; Scott, David A.; Westover, Kenneth D.; Gray, Nathanael S. (DFCI); (UTSMC); (Harvard-Med); (NYUSM)

2017-08-01

Targeted covalent small molecules have shown promise for cancers driven by KRAS G12C. Allosteric compounds that access an inducible pocket formed by movement of a dynamic structural element in KRAS, switch II, have been reported, but these compounds require further optimization to enable their advancement into clinical development. We demonstrate that covalent quinazoline-based switch II pocket (SIIP) compounds effectively suppress GTP loading of KRAS G12C, MAPK phosphorylation, and the growth of cancer cells harboring G12C. Notably we find that adding an amide substituent to the quinazoline scaffold allows additional interactions with KRAS G12C, and remarkably increases the labeling efficiency, potency, and selectivity of KRAS G12C inhibitors. Structural studies using X-ray crystallography reveal a new conformation of SIIP and key interactions made by substituents located at the quinazoline 2-, 4-, and 7-positions. Optimized lead compounds in the quinazoline series selectively inhibit KRAS G12C-dependent signaling and cancer cell growth at sub-micromolar concentrations.

Novel orally bioavailable EZH1/2 dual inhibitors with greater antitumor efficacy than an EZH2 selective inhibitor.

Science.gov (United States)

Honma, Daisuke; Kanno, Osamu; Watanabe, Jun; Kinoshita, Junzo; Hirasawa, Makoto; Nosaka, Emi; Shiroishi, Machiko; Takizawa, Takeshi; Yasumatsu, Isao; Horiuchi, Takao; Nakao, Akira; Suzuki, Keisuke; Yamasaki, Tomonori; Nakajima, Katsuyoshi; Hayakawa, Miho; Yamazaki, Takanori; Yadav, Ajay Singh; Adachi, Nobuaki

2017-10-01

Polycomb repressive complex 2 (PRC2) methylates histone H3 lysine 27 and represses gene expression to regulate cell proliferation and differentiation. Enhancer of zeste homolog 2 (EZH2) or its close homolog EZH1 functions as a catalytic subunit of PRC2, so there are two PRC2 complexes containing either EZH2 or EZH1. Tumorigenic functions of EZH2 and its synthetic lethality with some subunits of SWItch/Sucrose Non-Fermentable (SWI/SNF) chromatin remodeling complexes have been observed. However, little is known about the function of EZH1 in tumorigenesis. Herein, we developed novel, orally bioavailable EZH1/2 dual inhibitors that strongly and selectively inhibited methyltransferase activity of both EZH2 and EZH1. EZH1/2 dual inhibitors suppressed trimethylation of histone H3 lysine 27 in cells more than EZH2 selective inhibitors. They also showed greater antitumor efficacy than EZH2 selective inhibitor in vitro and in vivo against diffuse large B-cell lymphoma cells harboring gain-of-function mutation in EZH2. A hematological cancer panel assay indicated that EZH1/2 dual inhibitor has efficacy against some lymphomas, multiple myeloma, and leukemia with fusion genes such as MLL-AF9, MLL-AF4, and AML1-ETO. A solid cancer panel assay demonstrated that some cancer cell lines are sensitive to EZH1/2 dual inhibitor in vitro and in vivo. No clear correlation was detected between sensitivity to EZH1/2 dual inhibitor and SWI/SNF mutations, with a few exceptions. Severe toxicity was not seen in rats treated with EZH1/2 dual inhibitor for 14 days at drug levels higher than those used in the antitumor study. Our results indicate the possibility of EZH1/2 dual inhibitors for clinical applications. © 2017 The Authors. Cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese Cancer Association.

A comprehensive target selectivity survey of the BCR-ABL kinase inhibitor INNO-406 by kinase profiling and chemical proteomics in chronic myeloid leukemia cells.

Science.gov (United States)

Rix, U; Remsing Rix, L L; Terker, A S; Fernbach, N V; Hantschel, O; Planyavsky, M; Breitwieser, F P; Herrmann, H; Colinge, J; Bennett, K L; Augustin, M; Till, J H; Heinrich, M C; Valent, P; Superti-Furga, G

2010-01-01

Resistance to the BCR-ABL tyrosine kinase inhibitor imatinib poses a pressing challenge in treating chronic myeloid leukemia (CML). This resistance is often caused by point mutations in the ABL kinase domain or by overexpression of LYN. The second-generation BCR-ABL inhibitor INNO-406 is known to inhibit most BCR-ABL mutants and LYN efficiently. Knowledge of its full target spectrum would provide the molecular basis for potential side effects or suggest novel therapeutic applications and possible combination therapies. We have performed an unbiased chemical proteomics native target profile of INNO-406 in CML cells combined with functional assays using 272 recombinant kinases thereby identifying several new INNO-406 targets. These include the kinases ZAK, DDR1/2 and various ephrin receptors. The oxidoreductase NQO2, inhibited by both imatinib and nilotinib, is not a relevant target of INNO-406. Overall, INNO-406 has an improved activity over imatinib but a slightly broader target profile than both imatinib and nilotinib. In contrast to dasatinib and bosutinib, INNO-406 does not inhibit all SRC kinases and most TEC family kinases and is therefore expected to elicit fewer side effects. Altogether, these properties may make INNO-406 a valuable component in the drug arsenal against CML.

Discovery of core-structurally novel PTP1B inhibitors with specific selectivity containing oxindole-fused spirotetrahydrofurochroman by one-pot reaction.

Science.gov (United States)

Dong, Suzhen; Lei, Yubing; Jia, Shikun; Gao, Lixin; Li, Jia; Zhu, Tong; Liu, Shunying; Hu, Wenhao

2017-02-15

Protein tyrosine phosphatase 1B (PTP1B) has been proposed to be an ideal target for treatment of type II diabetes and obesity. However, no druggable PTP1B inhibitor has been established and there is still an urgent demand for the development of structurally novel PTPIB inhibitor. Herein, we reported core-structurally novel PTP1B inhibitors with low micromole-ranged inhibitory activity by one-pot reaction from simple starting materials. Further studies demonstrated some of these active compounds had a specific selectivity over other PTPs. The structure and activity relationship was also described. The best active and selective compound 5e inhibited PTP1B activity with an IC 50 of 4.53μM. Molecular docking analysis further demonstrated that compound 5e bound to the active pocket of PTP1B. The results might provide some insights for further development of new drugs for type II diabetes and obesity. Copyright © 2016 Elsevier Ltd. All rights reserved.

Structure-guided evolution of potent and selective CHK1 inhibitors through scaffold morphing.

Science.gov (United States)

Reader, John C; Matthews, Thomas P; Klair, Suki; Cheung, Kwai-Ming J; Scanlon, Jane; Proisy, Nicolas; Addison, Glynn; Ellard, John; Piton, Nelly; Taylor, Suzanne; Cherry, Michael; Fisher, Martin; Boxall, Kathy; Burns, Samantha; Walton, Michael I; Westwood, Isaac M; Hayes, Angela; Eve, Paul; Valenti, Melanie; de Haven Brandon, Alexis; Box, Gary; van Montfort, Rob L M; Williams, David H; Aherne, G Wynne; Raynaud, Florence I; Eccles, Suzanne A; Garrett, Michelle D; Collins, Ian

2011-12-22

Pyrazolopyridine inhibitors with low micromolar potency for CHK1 and good selectivity against CHK2 were previously identified by fragment-based screening. The optimization of the pyrazolopyridines to a series of potent and CHK1-selective isoquinolines demonstrates how fragment-growing and scaffold morphing strategies arising from a structure-based understanding of CHK1 inhibitor binding can be combined to successfully progress fragment-derived hit matter to compounds with activity in vivo. The challenges of improving CHK1 potency and selectivity, addressing synthetic tractability, and achieving novelty in the crowded kinase inhibitor chemical space were tackled by multiple scaffold morphing steps, which progressed through tricyclic pyrimido[2,3-b]azaindoles to N-(pyrazin-2-yl)pyrimidin-4-amines and ultimately to imidazo[4,5-c]pyridines and isoquinolines. A potent and highly selective isoquinoline CHK1 inhibitor (SAR-020106) was identified, which potentiated the efficacies of irinotecan and gemcitabine in SW620 human colon carcinoma xenografts in nude mice.

The Structural Basis of Cryptosporidium-Specific IMP Dehydrogenase Inhibitor Selectivity

Energy Technology Data Exchange (ETDEWEB)

MacPherson, Iain S.; Kirubakaran, Sivapriya; Gorla, Suresh Kumar; Riera, Thomas V.; D’Aquino, J. Alejandro; Zhang, Minjia; Cuny, Gregory D.; Hedstrom, Lizbeth (BWH); (Brandeis)

2010-03-29

Cryptosporidium parvum is a potential biowarfare agent, an important AIDS pathogen, and a major cause of diarrhea and malnutrition. No vaccines or effective drug treatment exist to combat Cryptosporidium infection. This parasite relies on inosine 5{prime}-monophosphate dehydrogenase (IMPDH) to obtain guanine nucleotides, and inhibition of this enzyme blocks parasite proliferation. Here, we report the first crystal structures of CpIMPDH. These structures reveal the structural basis of inhibitor selectivity and suggest a strategy for further optimization. Using this information, we have synthesized low-nanomolar inhibitors that display 10{sup 3} selectivity for the parasite enzyme over human IMPDH2.

The potency and specificity of the interaction between the IA3 inhibitor and its target aspartic proteinase from Saccharomyces cerevisiae

DEFF Research Database (Denmark)

Phylip, L H; Lees, W E; Brownsey, B G

2001-01-01

The yeast IA3 polypeptide consists of only 68 residues, and the free inhibitor has little intrinsic secondary structure. IA3 showed subnanomolar potency toward its target, proteinase A from Saccharomyces cerevisiae, and did not inhibit any of a large number of aspartic proteinases with similar...... by the nontarget aspartic proteinases, it was not cleaved by proteinase A. The random coil IA3 polypeptide escapes cleavage by being stabilized in a helical conformation upon interaction with the active site of proteinase A. This results, paradoxically, in potent selective inhibition of the target enzyme....

In silico screening for inhibitors of p-glycoprotein that target the nucleotide binding domains.

Science.gov (United States)

Brewer, Frances K; Follit, Courtney A; Vogel, Pia D; Wise, John G

2014-12-01

Multidrug resistances and the failure of chemotherapies are often caused by the expression or overexpression of ATP-binding cassette transporter proteins such as the multidrug resistance protein, P-glycoprotein (P-gp). P-gp is expressed in the plasma membrane of many cell types and protects cells from accumulation of toxins. P-gp uses ATP hydrolysis to catalyze the transport of a broad range of mostly hydrophobic compounds across the plasma membrane and out of the cell. During cancer chemotherapy, the administration of therapeutics often selects for cells which overexpress P-gp, thereby creating populations of cancer cells resistant to a variety of chemically unrelated chemotherapeutics. The present study describes extremely high-throughput, massively parallel in silico ligand docking studies aimed at identifying reversible inhibitors of ATP hydrolysis that target the nucleotide-binding domains of P-gp. We used a structural model of human P-gp that we obtained from molecular dynamics experiments as the protein target for ligand docking. We employed a novel approach of subtractive docking experiments that identified ligands that bound predominantly to the nucleotide-binding domains but not the drug-binding domains of P-gp. Four compounds were found that inhibit ATP hydrolysis by P-gp. Using electron spin resonance spectroscopy, we showed that at least three of these compounds affected nucleotide binding to the transporter. These studies represent a successful proof of principle demonstrating the potential of targeted approaches for identifying specific inhibitors of P-gp. Copyright © 2014 by The American Society for Pharmacology and Experimental Therapeutics.

Small Molecule Inhibitors That Selectively Block Dengue Virus Methyltransferase*

Science.gov (United States)

Lim, Siew Pheng; Sonntag, Louis Sebastian; Noble, Christian; Nilar, Shahul H.; Ng, Ru Hui; Zou, Gang; Monaghan, Paul; Chung, Ka Yan; Dong, Hongping; Liu, Boping; Bodenreider, Christophe; Lee, Gladys; Ding, Mei; Chan, Wai Ling; Wang, Gang; Jian, Yap Li; Chao, Alexander Theodore; Lescar, Julien; Yin, Zheng; Vedananda, T. R.; Keller, Thomas H.; Shi, Pei-Yong

2011-01-01

Crystal structure analysis of Flavivirus methyltransferases uncovered a flavivirus-conserved cavity located next to the binding site for its cofactor, S-adenosyl-methionine (SAM). Chemical derivatization of S-adenosyl-homocysteine (SAH), the product inhibitor of the methylation reaction, with substituents that extend into the identified cavity, generated inhibitors that showed improved and selective activity against dengue virus methyltransferase (MTase), but not related human enzymes. Crystal structure of dengue virus MTase with a bound SAH derivative revealed that its N6-substituent bound in this cavity and induced conformation changes in residues lining the pocket. These findings demonstrate that one of the major hurdles for the development of methyltransferase-based therapeutics, namely selectivity for disease-related methyltransferases, can be overcome. PMID:21147775

Clonal evolution of AML on novel FMS-like tyrosine kinase-3 (FLT3 inhibitor therapy with evolving actionable targets

Directory of Open Access Journals (Sweden)

Pashtoon M. Kasi

2016-01-01

Full Text Available For acute myeloid leukemia (AML, identification of activating mutations in the FMS-like tyrosine kinase-3 (FLT3 has led to the development of several FLT3-inhibitors. Here we present clinical and next generation sequencing data at the time of progression of a patient on a novel FLT3-inhibitor clinical trial (ASP2215 to show that employing therapeutic interventions with these novel targeted therapies can lead to consequences secondary to selective pressure and clonal evolution of cancer. We describe novel findings alongside data on treatment directed towards actionable aberrations acquired during the process. (Clinical Trial: NCT02014558; registered at: 〈https://clinicaltrials.gov/ct2/show/NCT02014558〉

Identification of Selective Inhibitors of the Plasmodium falciparum Hexose Transporter PfHT by Screening Focused Libraries of Anti-Malarial Compounds.

Directory of Open Access Journals (Sweden)

Diana Ortiz

Full Text Available 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.

Rasagiline (TVP-1012): a new selective monoamine oxidase inhibitor for Parkinson's disease.

Science.gov (United States)

Guay, David R P

2006-12-01

This article reviews the chemistry, pharmacodynamics, pharmacokinetics, clinical efficacy, tolerability, drug-interaction potential, indications, dosing, and potential role of rasagiline mesylate, a new selective monoamine oxidase (MAO) type B (MAO-B) inhibitor, in the treatment of Parkinson's disease. A MEDLINE/PUBMED search (1986 through September 2006) was conducted to identify studies involving rasagiline written in English. Additional references were obtained from the bibliographies of these studies. All studies evaluating any aspect of rasagiline, including in vitro, in vivo (animal), and human studies, were reviewed. Rasagiline mesylate was developed with the goal of producing a selective MAO-B inhibitor that is not metabolized to (presumed) toxic metabolites (eg, amphetamine and methamphetamine, which are byproducts of the metabolism of selegiline, another selective MAO-B inhibitor). In vitro and in vivo data have confirmed the drug's selectivity for MAO-B. Rasagiline is almost completely eliminated by oxidative metabolism (catalyzed by cytochrome P-450 [CYP] isozyme 1A2) followed by renal excretion of conjugated parent compound and metabolites. Drug clearance is sufficiently slow to allow once-daily dosing. Several studies have documented its efficacy as monotherapy for early-stage disease and as adjunctive therapy in L-dopa recipients with motor fluctuations. As monotherapy, rasagiline is well tolerated with an adverse-effect profile similar to that of placebo. As adjunctive therapy, it exhibits the expected adverse effects of dopamine excess, which can be ameliorated by reducing the L-dopa dosage. CYP1A2 inhibitors slow the elimination of rasagiline and mandate dosage reduction. Hepatic impairment has an analogous effect. The recommended dosage regimens for monotherapy and adjunctive therapy are 1 and 0.5 mg PO QD, respectively. Despite the well-documented selectivity of rasagiline, the manufacturer recommends virtually all of the dietary (vis

Small molecules, inhibitors of DNA-PK, targeting DNA repair and beyond

Directory of Open Access Journals (Sweden)

David eDavidson

2013-01-01

Full Text Available Many current chemotherapies function by damaging genomic DNA in rapidly dividing cells ultimately leading to cell death. This therapeutic approach differentially targets cancer cells that generally display rapid cell division compared to normal tissue cells. However, although these treatments are initially effective in arresting tumor growth and reducing tumor burden, resistance and disease progression eventually occur. A major mechanism underlying this resistance is increased levels of cellular DNA repair. Most cells have complex mechanisms in place to repair DNA damage that occurs due to environmental exposures or normal metabolic processes. These systems, initially overwhelmed when faced with chemotherapy induced DNA damage, become more efficient under constant selective pressure and as a result chemotherapies become less effective. Thus, inhibiting DNA repair pathways using target specific small molecule inhibitors may overcome cellular resistance to DNA damaging chemotherapies. Non-homologous end joining (NHEJ a major mechanism for the repair of double strand breaks (DSB in DNA is regulated in part by the serine/threonine kinase, DNA dependent protein kinase (DNA-PK. The DNA-PK holoenzyme acts as a scaffold protein tethering broken DNA ends and recruiting other repair molecules. It also has enzymatic activity that may be involved in DNA damage signaling. Because of its’ central role in repair of DSBs, DNA-PK has been the focus of a number of small molecule studies. In these studies specific DNA-PK inhibitors have shown efficacy in synergizing chemotherapies in vitro. However, compounds currently known to specifically inhibit DNA-PK are limited by poor pharmacokinetics: these compounds have poor solubility and have high metabolic lability in vivo leading to short serum half-lives. Future improvement in DNA-PK inhibition will likely be achieved by designing new molecules based on the recently reported crystallographic structure of DNA

Potent nonnucleoside reverse transcriptase inhibitors target HIV-1 Gag-Pol.

Directory of Open Access Journals (Sweden)

Anna Figueiredo

2006-11-01

Full Text Available Nonnucleoside reverse transcriptase inhibitors (NNRTIs target HIV-1 reverse transcriptase (RT by binding to a pocket in RT that is close to, but distinct, from the DNA polymerase active site and prevent the synthesis of viral cDNA. NNRTIs, in particular, those that are potent inhibitors of RT polymerase activity, can also act as chemical enhancers of the enzyme's inter-subunit interactions. However, the consequences of this chemical enhancement effect on HIV-1 replication are not understood. Here, we show that the potent NNRTIs efavirenz, TMC120, and TMC125, but not nevirapine or delavirdine, inhibit the late stages of HIV-1 replication. These potent NNRTIs enhanced the intracellular processing of Gag and Gag-Pol polyproteins, and this was associated with a decrease in viral particle production from HIV-1-transfected cells. The increased polyprotein processing is consistent with premature activation of the HIV-1 protease by NNRTI-enhanced Gag-Pol multimerization through the embedded RT sequence. These findings support the view that Gag-Pol multimerization is an important step in viral assembly and demonstrate that regulation of Gag-Pol/Gag-Pol interactions is a novel target for small molecule inhibitors of HIV-1 production. Furthermore, these drugs can serve as useful probes to further understand processes involved in HIV-1 particle assembly and maturation.

Dual-Targeting Small-Molecule Inhibitors of the Staphylococcus aureus FMN Riboswitch Disrupt Riboflavin Homeostasis in an Infectious Setting.

Science.gov (United States)

Wang, Hao; Mann, Paul A; Xiao, Li; Gill, Charles; Galgoci, Andrew M; Howe, John A; Villafania, Artjohn; Barbieri, Christopher M; Malinverni, Juliana C; Sher, Xinwei; Mayhood, Todd; McCurry, Megan D; Murgolo, Nicholas; Flattery, Amy; Mack, Matthias; Roemer, Terry

2017-05-18

Riboswitches are bacterial-specific, broadly conserved, non-coding RNA structural elements that control gene expression of numerous metabolic pathways and transport functions essential for cell growth. As such, riboswitch inhibitors represent a new class of potential antibacterial agents. Recently, we identified ribocil-C, a highly selective inhibitor of the flavin mononucleotide (FMN) riboswitch that controls expression of de novo riboflavin (RF, vitamin B2) biosynthesis in Escherichia coli. Here, we provide a mechanistic characterization of the antibacterial effects of ribocil-C as well as of roseoflavin (RoF), an antimetabolite analog of RF, among medically significant Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA) and Enterococcus faecalis. We provide genetic, biophysical, computational, biochemical, and pharmacological evidence that ribocil-C and RoF specifically inhibit dual FMN riboswitches, separately controlling RF biosynthesis and uptake processes essential for MRSA growth and pathogenesis. Such a dual-targeting mechanism is specifically required to develop broad-spectrum Gram-positive antibacterial agents targeting RF metabolism. Copyright © 2017 Elsevier Ltd. All rights reserved.

Allosteric Mutant IDH1 Inhibitors Reveal Mechanisms for IDH1 Mutant and Isoform Selectivity

Energy Technology Data Exchange (ETDEWEB)

Xie, Xiaoling; Baird, Daniel; Bowen, Kimberly; Capka, Vladimir; Chen, Jinyun; Chenail, Gregg; Cho, YoungShin; Dooley, Julia; Farsidjani, Ali; Fortin, Pascal; Kohls, Darcy; Kulathila, Raviraj; Lin, Fallon; McKay, Daniel; Rodrigues, Lindsey; Sage, David; Touré, B. Barry; van der Plas, Simon; Wright, Kirk; Xu, Ming; Yin, Hong; Levell, Julian; Pagliarini, Raymond A. (Novartis)

2017-03-01

Oncogenic IDH1 and IDH2 mutations contribute to cancer via production of R-2-hydroxyglutarate (2-HG). Here, we characterize two structurally distinct mutant- and isoform-selective IDH1 inhibitors that inhibit 2-HG production. Both bind to an allosteric pocket on IDH1, yet shape it differently, highlighting the plasticity of this site. Oncogenic IDH1R132H mutation destabilizes an IDH1 “regulatory segment,” which otherwise restricts compound access to the allosteric pocket. Regulatory segment destabilization in wild-type IDH1 promotes inhibitor binding, suggesting that destabilization is critical for mutant selectivity. We also report crystal structures of oncogenic IDH2 mutant isoforms, highlighting the fact that the analogous segment of IDH2 is not similarly destabilized. This intrinsic stability of IDH2 may contribute to observed inhibitor IDH1 isoform selectivity. Moreover, discrete residues in the IDH1 allosteric pocket that differ from IDH2 may also guide IDH1 isoform selectivity. These data provide a deeper understanding of how IDH1 inhibitors achieve mutant and isoform selectivity.

Rational Design of a Highly Potent and Selective Peptide Inhibitor of PACE4 by Salt Bridge Interaction with D160 at Position P3.

Science.gov (United States)

Dianati, Vahid; Shamloo, Azar; Kwiatkowska, Anna; Desjardins, Roxane; Soldera, Armand; Day, Robert; Dory, Yves L

2017-08-08

PACE4, a member of the proprotein convertases (PCs) family of serine proteases, is a validated target for prostate cancer. Our group has developed a potent and selective PACE4 inhibitor: Ac-LLLLRVKR-NH 2 . In seeking for modifications to increase the selectivity of this ligand toward PACE4, we replaced one of its P3 Val methyl groups with a basic group capable of forming a salt bridge with D160 of PACE4. The resulting inhibitor is eight times more potent than the P3 Val parent inhibitor and two times more selective over furin, because the equivalent salt bridge with furin E257 is not optimal. Moreover, the β-branched nature of the new P3 residue favors the extended β-sheet conformation usually associated with substrates of proteases. This work provides new insight for better understanding of β-sheet backbone-backbone interactions between serine proteases and their peptidic ligands. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Efficacy and tolerability of lumiracoxib, a highly selective cyclo-oxygenase-2 (COX2 inhibitor, in the management of pain and osteoarthritis

Directory of Open Access Journals (Sweden)

Piet Geusens

2008-04-01

Full Text Available Piet Geusens1, Willem Lems21Department of Internal Medicine, Subdivision of Rheumatology, University Hospital, Maastricht, The Netherlands and Biomedical Research Institute, University Hasselt, Belgium; 2Vrije Universiteit Medical Centre, Department of Rheumatology, Amsterdam, the NetherlandsAbstract: Lumiracoxib is a COX2 inhibitor that is highly selective, is more effective than placebo on pain in osteoarthritis (OA, with similar analgesic and anti-inflammatory effects as non-selective NSAIDs and the selective COX2 inhibitor celecoxib, has a lower incidence of upper gastrointestinal (GI side effects in patients not taking aspirin, and a similar incidence of cardiovascular (CV side effects compared to naproxen or ibuprofen. In the context of earlier guidelines and taking into account the GI and CV safety results of the TARGET study, lumiracoxib had secured European Medicines Agency (EMEA approval with as indication symptomatic treatment of OA as well as short-term management of acute pain associated with primary dysmenorrhea and following orthopedic or dental surgery. In the complex clinical context of efficiency and safety of selective and non-selective COX inhibitors, its prescription and use should be based on the risk and safety profile of the patient. In addition, there is further need for long-term GI and CV safety studies and general post-marketing safety on its use in daily practice. Meanwhile, at the time of submission of this manuscript, the EMEA has withdrawn lumiracoxib throughout Europe because of the risk of serious side effects affecting the liver.Keywords: lumiracoxib, NSAIDs, COX2 inhibitors, gastro-intestinal and cardiovascular safety

Histone deacetylase (HDAC) inhibitors targeting HDAC3 and HDAC1 ameliorate polyglutamine-elicited phenotypes in model systems of Huntington's disease

Science.gov (United States)

Jia, Haiqun; Pallos, Judit; Jacques, Vincent; Lau, Alice; Tang, Bin; Cooper, Andrew; Syed, Adeela; Purcell, Judith; Chen, Yi; Sharma, Shefali; Sangrey, Gavin R.; Darnell, Shayna B.; Plasterer, Heather; Sadri-Vakili, Ghazaleh; Gottesfeld, Joel M.; Thompson, Leslie M.; Rusche, James R.; Marsh, J. Lawrence; Thomas, Elizabeth A.

2012-01-01

We have previously demonstrated amelioration of Huntington's disease (HD)-related phenotypes in R6/2 transgenic mice in response to treatment with the novel histone deacetylase (HDAC) inhibitor 4b. Here we have measured the selectivity profiles of 4b and related compounds against class I and class II HDACs and have tested their ability to restore altered expression of genes related to HD pathology in mice and to rescue disease effects in cell culture and Drosophila models of HD. R6/2 transgenic and wild-type (wt) mice received daily injections of HDAC inhibitors for 3 days followed by real-time PCR analysis to detect expression differences for 13 HD-related genes. We find that HDACi 4b and 136, two compounds showing high potency for inhibiting HDAC3 were most effective in reversing the expression of genes relevant to HD, including Ppp1r1b, which encodes DARPP-32, a marker for medium spiny striatal neurons. In contrast, compounds targeting HDAC1 were less effective at correcting gene expression abnormalities in R6/2 transgenic mice, but did cause significant increases in the expression of selected genes. An additional panel of 4b-related compounds was tested in a Drosophila model of HD and in STHdhQ111 striatal cells to further distinguish HDAC selectivity. Significant improvement in huntingtin-elicited Drosophila eye neurodegeneration in the fly was observed in response to treatment with compounds targeting human HDAC1 and/or HDAC3. In STHdhQ111 striatal cells, the ability of HDAC inhibitors to improve Htt-elicited metabolic deficits correlated with the potency at inhibiting HDAC1 and HDAC3, although the IC50 values for HDAC1 inhibition were typically 10-fold higher than for inhibition of HDAC3. Assessment of HDAC protein localization in brain tissue by Western blot analysis revealed accumulation of HDAC1 and HDAC3 in the nucleus of HD transgenic mice compared to wt mice, with a concurrent decrease in cytoplasmic localization, suggesting that these HDACs contribute

DUPA conjugation of a cytotoxic indenoisoquinoline topoisomerase I inhibitor for selective prostate cancer cell targeting.

Science.gov (United States)

Roy, Jyoti; Nguyen, Trung Xuan; Kanduluru, Ananda Kumar; Venkatesh, Chelvam; Lv, Wei; Reddy, P V Narasimha; Low, Philip S; Cushman, Mark

2015-04-09

Prostate-specific membrane antigen (PSMA) is overexpressed in most prostate cancer cells while being present at low or undetectable levels in normal cells. This difference provides an opportunity to selectively deliver cytotoxic drugs to prostate cancer cells while sparing normal cells that lack PSMA, thus improving potencies and reducing toxicities. PSMA has high affinity for 2-[3-(1,3-dicarboxypropyl)ureido]pentanedioic acid (DUPA) (Ki = 8 nM). After binding to a DUPA-drug conjugate, PSMA internalizes, unloads the conjugate, and returns to the surface. In the present studies, an indenoisoquinoline topoisomerase I inhibitor was conjugated to DUPA via a peptide linker and a drug-release segment that facilitates intracellular cleavage to liberate the drug cargo. The DUPA-indenoisoquinoline conjugate exhibited an IC50 in the low nanomolar range in 22RV1 cell cultures and induced a complete cessation of tumor growth with no toxicity, as determined by loss of body weight and death of treated mice.

New approaches of PARP-1 inhibitors in human lung cancer cells and cancer stem-like cells by some selected anthraquinone-derived small molecules.

Directory of Open Access Journals (Sweden)

Yu-Ru Lee

Full Text Available Poly (ADP-ribose polymerase-1 (PARP-1 and telomerase, as well as DNA damage response pathways are targets for anticancer drug development, and specific inhibitors are currently under clinical investigation. The purpose of this work is to evaluate anticancer activities of anthraquinone-derived tricyclic and tetracyclic small molecules and their structure-activity relationships with PARP-1 inhibition in non-small cell lung cancer (NSCLC and NSCLC-overexpressing Oct4 and Nanog clone, which show high-expression of PARP-1 and more resistance to anticancer drug. We applied our library selected compounds to NCI's 60 human cancer cell-lines (NCI-60 in order to generate systematic profiling data. Based on our analysis, it is hypothesized that these drugs might be, directly and indirectly, target components to induce mitochondrial permeability transition and the release of pro-apoptotic factors as potential anti-NSCLC or PARP inhibitor candidates. Altogether, the most active NSC747854 showed its cytotoxicity and dose-dependent PARP inhibitory manner, thus it emerges as a promising structure for anti-cancer therapy with no significant negative influence on normal cells. Our studies present evidence that telomere maintenance should be taken into consideration in efforts not only to overcome drug resistance, but also to optimize the use of telomere-based therapeutics. These findings will be of great value to facilitate structure-based design of selective PARP inhibitors, in general, and telomerase inhibitors, in particular. Together, the data presented here expand our insight into the PARP inhibitors and support the resource-demanding lead optimization of structurally related small molecules for human cancer therapy.

New Approaches of PARP-1 Inhibitors in Human Lung Cancer Cells and Cancer Stem-Like Cells by Some Selected Anthraquinone-Derived Small Molecules

Science.gov (United States)

Yu, Dah-Shyong; Huang, Kuo-Feng; Chou, Shih-Jie; Chen, Tsung-Chih; Lee, Chia-Chung; Chen, Chun-Liang; Chiou, Shih-Hwa; Huang, Hsu-Shan

2013-01-01

Poly (ADP-ribose) polymerase-1 (PARP-1) and telomerase, as well as DNA damage response pathways are targets for anticancer drug development, and specific inhibitors are currently under clinical investigation. The purpose of this work is to evaluate anticancer activities of anthraquinone-derived tricyclic and tetracyclic small molecules and their structure-activity relationships with PARP-1 inhibition in non-small cell lung cancer (NSCLC) and NSCLC-overexpressing Oct4 and Nanog clone, which show high-expression of PARP-1 and more resistance to anticancer drug. We applied our library selected compounds to NCI's 60 human cancer cell-lines (NCI-60) in order to generate systematic profiling data. Based on our analysis, it is hypothesized that these drugs might be, directly and indirectly, target components to induce mitochondrial permeability transition and the release of pro-apoptotic factors as potential anti-NSCLC or PARP inhibitor candidates. Altogether, the most active NSC747854 showed its cytotoxicity and dose-dependent PARP inhibitory manner, thus it emerges as a promising structure for anti-cancer therapy with no significant negative influence on normal cells. Our studies present evidence that telomere maintenance should be taken into consideration in efforts not only to overcome drug resistance, but also to optimize the use of telomere-based therapeutics. These findings will be of great value to facilitate structure-based design of selective PARP inhibitors, in general, and telomerase inhibitors, in particular. Together, the data presented here expand our insight into the PARP inhibitors and support the resource-demanding lead optimization of structurally related small molecules for human cancer therapy. PMID:23451039

Removal of PCR inhibitors using dielectrophoresis as a selective filter in a microsystem

DEFF Research Database (Denmark)

Perch-Nielsen, Ivan Ryberg; Bang, Dang Duong; Poulsen, Claus Riber

2003-01-01

, the removal of PCR inhibitors in sample preparation steps is essential and several methods have been published. The methods are either chemical or based on filtering. Conventional ways of filtering include mechanical filters or washing e. g. by centrifugation. Another way of filtering is the use of electric...... to manipulate cells in many microstructures. In this study, we used DEP as a selective filter for holding cells in a microsystem while the PCR inhibitors were flushed out of the system. Haemoglobin and heparin-natural components of blood-were selected as PCR inhibitors, since the inhibitory effects...

Treatment of selective mutism: focus on selective serotonin reuptake inhibitors.

Science.gov (United States)

Kaakeh, Yaman; Stumpf, Janice L

2008-02-01

Abstract Selective mutism is a pediatric psychiatric disorder that occurs when a child consistently fails to speak in specific situations in which speaking is expected, such as at school and social gatherings, but speaks appropriately in other settings. Selective mutism often is diagnosed when a child starts school and does not talk to teachers or peers, but talks to family members at home; the condition is frequently accompanied by anxiety and shyness. Although the underlying etiology of the condition remains unclear, psychotherapy is the preferred initial treatment, with the support of parents and teachers. If the child does not respond to psychotherapy, addition of pharmacologic treatment should be considered, depending on the severity of symptoms and presence of other illnesses. Although data are limited to case reports and trials with small patient populations and short follow-up periods, some patients with selective mutism respond to therapy with selective serotonin reuptake inhibitors (SSRIs). Fluoxetine is the most studied SSRI as treatment for the condition, although further investigation is required to determine the optimal dosage and duration of therapy.

Structure-based lead optimization to improve antiviral potency and ADMET properties of phenyl-1H-pyrrole-carboxamide entry inhibitors targeted to HIV-1 gp120.

Science.gov (United States)

Curreli, Francesca; Belov, Dmitry S; Kwon, Young Do; Ramesh, Ranjith; Furimsky, Anna M; O'Loughlin, Kathleen; Byrge, Patricia C; Iyer, Lalitha V; Mirsalis, Jon C; Kurkin, Alexander V; Altieri, Andrea; Debnath, Asim K

2018-05-12

We are continuing our concerted effort to optimize our first lead entry antagonist, NBD-11021, which targets the Phe43 cavity of the HIV-1 envelope glycoprotein gp120, to improve antiviral potency and ADMET properties. In this report, we present a structure-based approach that helped us to generate working hypotheses to modify further a recently reported advanced lead entry antagonist, NBD-14107, which showed significant improvement in antiviral potency when tested in a single-cycle assay against a large panel of Env-pseudotyped viruses. We report here the synthesis of twenty-nine new compounds and evaluation of their antiviral activity in a single-cycle and multi-cycle assay to derive a comprehensive structure-activity relationship (SAR). We have selected three inhibitors with the high selectivity index for testing against a large panel of 55 Env-pseudotyped viruses representing a diverse set of clinical isolates of different subtypes. The antiviral activity of one of these potent inhibitors, 55 (NBD-14189), against some clinical isolates was as low as 63 nM. We determined the sensitivity of CD4-binding site mutated-pseudoviruses to these inhibitors to confirm that they target HIV-1 gp120. Furthermore, we assessed their ADMET properties and compared them to the clinical candidate attachment inhibitor, BMS-626529. The ADMET data indicate that some of these new inhibitors have comparable ADMET properties to BMS-626529 and can be optimized further to potential clinical candidates. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

The selective Aurora B kinase inhibitor AZD1152 is a potential new treatment for multiple myeloma.

Science.gov (United States)

Evans, Robert P; Naber, Claudia; Steffler, Tara; Checkland, Tamara; Maxwell, Christopher A; Keats, Jonathan J; Belch, Andrew R; Pilarski, Linda M; Lai, Raymond; Reiman, Tony

2008-02-01

Aurora kinases are potential targets for cancer therapy. Previous studies have validated Aurora kinase A as a therapeutic target in multiple myeloma (MM), and have demonstrated in vitro anti-myeloma effects of small molecule Aurora kinase inhibitors that inhibit both Aurora A and B. This study demonstrated that Aurora B kinase was strongly expressed in myeloma cell lines and primary plasma cells. The selective Aurora B inhibitor AZD1152-induced apoptotic death in myeloma cell lines at nanomolar concentrations, with a cell cycle phenotype consistent with that reported previously for Aurora B inhibition. In some cases, AZD1152 in combination with dexamethasone showed increased anti-myeloma activity compared with the use of either agent alone. AZD1152 was active against sorted CD138(+) BM plasma cells from myeloma patients but also, as expected, was toxic to CD138(-) marrow cells from the same patients. In a murine myeloma xenograft model, AZD1152-inhibited tumour growth at well-tolerated doses and induced cell death in established tumours, with associated mild, transient leucopenia. AZD1152 shows promise in these preclinical studies as a novel treatment for MM.

A Holistic In silico Approach to Develop Novel Inhibitors Targeting ...

African Journals Online (AJOL)

Purpose: To design a dual inhibitor of natural origin capable of targeting ErbB1 and ErbB2 kinases for the treatment of lung cancer. Method: Advanced In silico drug designing techniques were explored in this study. Sequence and structure analysis of ErbB1 and ErbB2 was followed by three dimensional (3D) ...

Design and Discovery of N -(2-Methyl-5'-morpholino-6'-((tetrahydro-2 H -pyran-4-yl)oxy)-[3,3'-bipyridin]-5-yl)-3-(trifluoromethyl)benzamide (RAF709): A Potent, Selective, and Efficacious RAF Inhibitor Targeting RAS Mutant Cancers

Energy Technology Data Exchange (ETDEWEB)

Nishiguchi, Gisele A.; Rico, Alice; Tanner, Huw; Aversa, Robert J.; Taft, Benjamin R.; Subramanian, Sharadha; Setti, Lina; Burger, Matthew T.; Wan, Lifeng; Tamez, Victoriano; Smith, Aaron; Lou, Yan; Barsanti, Paul A.; Appleton, Brent A.; Mamo, Mulugeta; Tandeske, Laura; Dix, Ina; Tellew, John E.; Huang, Shenlin; Griner, Lesley A. Mathews; Cooke, Vesselina G.; Van Abbema, Anne; Merritt, Hanne; Ma, Sylvia; Gampa, Kalyani; Feng, Fei; Yuan, Jing; Wang, Yingyun; Haling, Jacob R.; Vaziri; #8741; , Sepideh; Hekmat-Nejad, Mohammad; Jansen, Johanna M.; Polyakov, Valery; Zang, Richard; Sethuraman, Vijay; Amiri, Payman; Singh, Mallika; Lees, Emma; Shao, Wenlin; Stuart, Darrin D.; Dillon, Michael P.; Ramurthy, Savithri (Novartis)

2017-06-06

RAS oncogenes have been implicated in >30% of human cancers, all representing high unmet medical need. The exquisite dependency on CRAF kinase in KRAS mutant tumors has been established in genetically engineered mouse models and human tumor cells. To date, many small molecule approaches are under investigation to target CRAF, yet kinase-selective and cellular potent inhibitors remain challenging to identify. Herein, we describe 14 (RAF709) [Aversa, Biaryl amide compounds as kinase inhibitors and their preparation. WO 2014151616, 2014], a selective B/C RAF inhibitor, which was developed through a hypothesis-driven approach focusing on drug-like properties. A key challenge encountered in the medicinal chemistry campaign was maintaining a balance between good solubility and potent cellular activity (suppression of pMEK and proliferation) in KRAS mutant tumor cell lines. We investigated the small molecule crystal structure of lead molecule 7 and hypothesized that disruption of the crystal packing would improve solubility, which led to a change from N-methylpyridone to a tetrahydropyranyl oxy-pyridine derivative. 14 proved to be soluble, kinase selective, and efficacious in a KRAS mutant xenograft model.

Discovery and preclinical pharmacology of a selective ATP-competitive Akt inhibitor (GDC-0068) for the treatment of human tumors.

Science.gov (United States)

Blake, James F; Xu, Rui; Bencsik, Josef R; Xiao, Dengming; Kallan, Nicholas C; Schlachter, Stephen; Mitchell, Ian S; Spencer, Keith L; Banka, Anna L; Wallace, Eli M; Gloor, Susan L; Martinson, Matthew; Woessner, Richard D; Vigers, Guy P A; Brandhuber, Barbara J; Liang, Jun; Safina, Brian S; Li, Jun; Zhang, Birong; Chabot, Christine; Do, Steven; Lee, Leslie; Oeh, Jason; Sampath, Deepak; Lee, Brian B; Lin, Kui; Liederer, Bianca M; Skelton, Nicholas J

2012-09-27

The discovery and optimization of a series of 6,7-dihydro-5H-cyclopenta[d]pyrimidine compounds that are ATP-competitive, selective inhibitors of protein kinase B/Akt is reported. The initial design and optimization was guided by the use of X-ray structures of inhibitors in complex with Akt1 and the closely related protein kinase A. The resulting compounds demonstrate potent inhibition of all three Akt isoforms in biochemical assays and poor inhibition of other members of the cAMP-dependent protein kinase/protein kinase G/protein kinase C extended family and block the phosphorylation of multiple downstream targets of Akt in human cancer cell lines. Biological studies with one such compound, 28 (GDC-0068), demonstrate good oral exposure resulting in dose-dependent pharmacodynamic effects on downstream biomarkers and a robust antitumor response in xenograft models in which the phosphatidylinositol 3-kinase-Akt-mammalian target of rapamycin pathway is activated. 28 is currently being evaluated in human clinical trials for the treatment of cancer.

Association between selective serotonin reuptake inhibitors and upper gastrointestinal bleeding: population based case-control study

Science.gov (United States)

de Abajo, Francisco José; Rodríguez, Luis Alberto García; Montero, Dolores

1999-01-01

Objective To examine the association between selective serotonin reuptake inhibitors and risk of upper gastrointestinal bleeding. Design Population based case-control study. Setting General practices included in the UK general practice research database. Subjects 1651 incident cases of upper gastrointestinal bleeding and 248 cases of ulcer perforation among patients aged 40 to 79 years between April 1993 and September 1997, and 10 000 controls matched for age, sex, and year that the case was identified. Interventions Review of computer profiles for all potential cases, and an internal validation study to confirm the accuracy of the diagnosis on the basis of the computerised information. Main outcome measures Current use of selective serotonin reuptake inhibitors or other antidepressants within 30 days before the index date. Results Current exposure to selective serotonin reuptake inhibitors was identified in 3.1% (52 of 1651) of patients with upper gastrointestinal bleeding but only 1.0% (95 of 10 000) of controls, giving an adjusted rate ratio of 3.0 (95% confidence interval 2.1 to 4.4). This effect measure was not modified by sex, age, dose, or treatment duration. A crude incidence of 1 case per 8000 prescriptions was estimated. A small association was found with non-selective serotonin reuptake inhibitors (relative risk 1.4, 1.1 to 1.9) but not with antidepressants lacking this inhibitory effect. None of the groups of antidepressants was associated with ulcer perforation. The concurrent use of selective serotonin reuptake inhibitors with non-steroidal anti-inflammatory drugs increased the risk of upper gastrointestinal bleeding beyond the sum of their independent effects (15.6, 6.6 to 36.6). A smaller interaction was also found between selective serotonin reuptake inhibitors and low dose aspirin (7.2, 3.1 to 17.1). Conclusions Selective serotonin reuptake inhibitors increase the risk of upper gastrointestinal bleeding. The absolute effect is, however

Loss in MCL-1 function sensitizes non-Hodgkin's lymphoma cell lines to the BCL-2-selective inhibitor venetoclax (ABT-199)

International Nuclear Information System (INIS)

Phillips, D C; Xiao, Y; Lam, L T; Litvinovich, E; Roberts-Rapp, L; Souers, A J; Leverson, J D

2015-01-01

As a population, non-Hodgkin's lymphoma (NHL) cell lines positive for the t(14;18) translocation and/or possessing elevated BCL2 copy number (CN; BCL2 High ) are exquisitely sensitive to navitoclax or the B-cell lymphoma protein-2 (BCL-2)-selective inhibitor venetoclax. Despite this, some BCL2 High cell lines remain resistant to either agent. Here we show that the MCL-1-specific inhibitor A-1210477 sensitizes these cell lines to navitoclax. Chemical segregation of this synergy with the BCL-2-selective inhibitor venetoclax or BCL-X L -selective inhibitor A-1155463 indicated that MCL-1 and BCL-2 are the two key anti-apoptotic targets for sensitization. Similarly, the CDK inhibitor flavopiridol downregulated MCL-1 expression and synergized with venetoclax in BCL2 High NHL cell lines to a similar extent as A-1210477. A-1210477 also synergized with navitoclax in the majority of BCL2 Low NHL cell lines. However, chemical segregation with venetoclax or A-1155463 revealed that synergy was driven by BCL-X L inhibition in this population. Collectively these data emphasize that BCL2 status is predictive of venetoclax potency in NHL not only as a single agent, but also in the adjuvant setting with anti-tumorigenic agents that inhibit MCL-1 function. These studies also potentially identify a patient population (BCL2 Low ) that could benefit from BCL-X L (navitoclax)-driven combination therapy

Prenatal exposure to selective serotonin reuptake inhibitors and childhood overweight at 7 years of age

DEFF Research Database (Denmark)

Grzeskowiak, Luke E; Gilbert, Andrew L; Sørensen, Thorkild

2013-01-01

To investigate a possible association between prenatal selective serotonin reuptake inhibitor (SSRI) exposure and childhood overweight at 7 years of age.......To investigate a possible association between prenatal selective serotonin reuptake inhibitor (SSRI) exposure and childhood overweight at 7 years of age....

Mixture and single-substance toxicity of selective serotonin reuptake inhibitors toward algae and crustaceans

DEFF Research Database (Denmark)

Christensen, Anne Munch; Faaborg-Andersen, S.; Ingerslev, Flemming

2007-01-01

Selective serotonin reuptake inhibitors (SSRIs) are used as antidepressant medications. primarily in the treatment of clinical depression. They are among the pharmaceuticals most often Prescribed in the industrialized countries. Selective serotonin reuptake inhibitors are compounds with an identi......Selective serotonin reuptake inhibitors (SSRIs) are used as antidepressant medications. primarily in the treatment of clinical depression. They are among the pharmaceuticals most often Prescribed in the industrialized countries. Selective serotonin reuptake inhibitors are compounds...... with an identical mechanism of action in mammals (inhibit reuptake of serotonin), and they have been found in different aqeous as well as biological samples collected in the environment. In the present study, we tested the toxicities of five SSRIs (citalopram, fluoxetine, fluoxamine, paroxetine, and sertraline.......027 to 1.6 mg/L, and in daphnids, test EC50s ranged from 0.92 to 20 mg/L, with sertraline being one of the most toxic compounds. The test design and statistical analysis of results from mixture tests were based on isobole analysis. It was demonstrated that the mixture toxicity of the SSRIs in the two...

Enhancement of vascular targeting by inhibitors of nitric oxide synthase

International Nuclear Information System (INIS)

Davis, Peter D.; Tozer, Gillian M.; Naylor, Matthew A.; Thomson, Peter; Lewis, Gemma; Hill, Sally A.

2002-01-01

Purpose: This study investigates the enhancement of the vascular targeting activity of the tubulin-binding agent combretastatin A4 phosphate (CA4P) by various inhibitors of nitric oxide synthases. Methods and Materials: The syngeneic tumors CaNT and SaS growing in CBA mice were used for this study. Reduction in perfused vascular volume was measured by injection of Hoechst 33342 24 h after drug administration. Necrosis (hematoxylin and eosin stain) was assessed also at 24 h after treatment. Combretastatin A4 phosphate was synthesized by a modification of the published procedure and the nitric oxide synthase inhibitors L-NNA, L-NMMA, L-NIO, L-NIL, S-MTC, S-EIT, AMP, AMT, and L-TC, obtained from commercial sources. Results: A statistically significant augmentation of the reduction in perfused vascular volume by CA4P in the CaNT tumor was observed with L-NNA, AMP, and AMT. An increase in CA4P-induced necrosis in the same tumor achieved significance with L-NNA, L-NMMA, L-NIL, and AMT. CA4P induced little necrosis in the SaS tumor, but combination with the inhibitors L-NNA, L-NMMA, L-NIO, S-EIT, and L-TC was effective. Conclusions: Augmentation of CA4P activity by nitric oxide synthase inhibitors of different structural classes supports a nitric oxide-related mechanism for this effect. L-NNA was the most effective inhibitor studied

A screen for kinase inhibitors identifies antimicrobial imidazopyridine aminofurazans as specific inhibitors of the Listeria monocytogenes PASTA kinase PrkA.

Science.gov (United States)

Schaenzer, Adam J; Wlodarchak, Nathan; Drewry, David H; Zuercher, William J; Rose, Warren E; Striker, Rob; Sauer, John-Demian

2017-10-13

Bacterial signaling systems such as protein kinases and quorum sensing have become increasingly attractive targets for the development of novel antimicrobial agents in a time of rising antibiotic resistance. The family of bacterial P enicillin-binding-protein A nd S erine/ T hreonine kinase- A ssociated (PASTA) kinases is of particular interest due to the role of these kinases in regulating resistance to β-lactam antibiotics. As such, small-molecule kinase inhibitors that target PASTA kinases may prove beneficial as treatments adjunctive to β-lactam therapy. Despite this interest, only limited progress has been made in identifying functional inhibitors of the PASTA kinases that have both activity against the intact microbe and high kinase specificity. Here, we report the results of a small-molecule screen that identified GSK690693, an imidazopyridine aminofurazan-type kinase inhibitor that increases the sensitivity of the intracellular pathogen Listeria monocytogenes to various β-lactams by inhibiting the PASTA kinase PrkA. GSK690693 potently inhibited PrkA kinase activity biochemically and exhibited significant selectivity for PrkA relative to the Staphylococcus aureus PASTA kinase Stk1. Furthermore, other imidazopyridine aminofurazans could effectively inhibit PrkA and potentiate β-lactam antibiotic activity to varying degrees. The presence of the 2-methyl-3-butyn-2-ol (alkynol) moiety was important for both biochemical and antimicrobial activity. Finally, mutagenesis studies demonstrated residues in the back pocket of the active site are important for GSK690693 selectivity. These data suggest that targeted screens can successfully identify PASTA kinase inhibitors with both biochemical and antimicrobial specificity. Moreover, the imidazopyridine aminofurazans represent a family of PASTA kinase inhibitors that have the potential to be optimized for selective PASTA kinase inhibition.

Side Effects of Nitrification Inhibitors on Non Target Microbial Processes in Soils

OpenAIRE

Johannes Carl Gottlieb Ottow; Gero Benckiser; Ferisman Tindaon

2011-01-01

Agricultural chemicals have been used extensively in modern agriculture and toxicological studies suggest a great potential for inducing undesirable effects on non target organisms. A model experiment was conducted in order to determine side effects of three nitrification inhibitors (NIs, 3,4dimethylpyrazolephosphate = DMPP, 4-Chlormethylpyrazole phosphate = ClMPP and dicyandiamide = DCD) on non target microbial processes in soils. Side effects and dose response curve of three NIs were quanti...

The Bruton Tyrosine Kinase (BTK) Inhibitor Acalabrutinib Demonstrates Potent On-Target Effects and Efficacy in Two Mouse Models of Chronic Lymphocytic Leukemia

DEFF Research Database (Denmark)

Herman, Sarah E M; Montraveta, Arnau; Niemann, Carsten U

2017-01-01

into the drinking water.Results: Utilizing biochemical assays, we demonstrate that acalabrutinib is a highly selective BTK inhibitor as compared with ibrutinib. In the human CLL NSG xenograft model, treatment with acalabrutinib demonstrated on-target effects, including decreased phosphorylation of PLCγ2, ERK......). In two complementary mouse models of CLL, acalabrutinib significantly reduced tumor burden and increased survival compared with vehicle treatment. Overall, acalabrutinib showed increased BTK selectivity compared with ibrutinib while demonstrating significant antitumor efficacy in vivo on par...... with ibrutinib. Clin Cancer Res; 23(11); 2831-41. ©2016 AACR....

The market dynamics of selective serotonin re-uptake inhibitors: a ...

African Journals Online (AJOL)

The market dynamics of selective serotonin re-uptake inhibitors: a private sector study in South Africa. Frasia Oosthuizen, Pariksha Jolene Kondiah, Hawa Bibi Moosa, Siddiqa Naroth, Nabeel Ismail Patel, Divashnee Reddy, Amanda Soobramoney ...

Discovery of Selective Phosphodiesterase 1 Inhibitors with Memory Enhancing Properties.

Science.gov (United States)

Dyck, Brian; Branstetter, Bryan; Gharbaoui, Tawfik; Hudson, Andrew R; Breitenbucher, J Guy; Gomez, Laurent; Botrous, Iriny; Marrone, Tami; Barido, Richard; Allerston, Charles K; Cedervall, E Peder; Xu, Rui; Sridhar, Vandana; Barker, Ryan; Aertgeerts, Kathleen; Schmelzer, Kara; Neul, David; Lee, Dong; Massari, Mark Eben; Andersen, Carsten B; Sebring, Kristen; Zhou, Xianbo; Petroski, Robert; Limberis, James; Augustin, Martin; Chun, Lawrence E; Edwards, Thomas E; Peters, Marco; Tabatabaei, Ali

2017-04-27

A series of potent thienotriazolopyrimidinone-based PDE1 inhibitors was discovered. X-ray crystal structures of example compounds from this series in complex with the catalytic domain of PDE1B and PDE10A were determined, allowing optimization of PDE1B potency and PDE selectivity. Reduction of hERG affinity led to greater than a 3000-fold selectivity for PDE1B over hERG. 6-(4-Methoxybenzyl)-9-((tetrahydro-2H-pyran-4-yl)methyl)-8,9,10,11-tetrahydropyrido[4',3':4,5]thieno[3,2-e][1,2,4]triazolo[1,5-c]pyrimidin-5(6H)-one was identified as an orally bioavailable and brain penetrating PDE1B enzyme inhibitor with potent memory-enhancing effects in a rat model of object recognition memory.

Rapid screening of selective serotonin re-uptake inhibitors in urine samples using solid-phase microextraction gas chromatography-mass spectrometry.

Science.gov (United States)

Salgado-Petinal, Carmen; Lamas, J Pablo; Garcia-Jares, Carmen; Llompart, Maria; Cela, Rafael

2005-07-01

In this paper a solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) method is proposed for a rapid analysis of some frequently prescribed selective serotonin re-uptake inhibitors (SSRI)-venlafaxine, fluvoxamine, mirtazapine, fluoxetine, citalopram, and sertraline-in urine samples. The SPME-based method enables simultaneous determination of the target SSRI after simple in-situ derivatization of some of the target compounds. Calibration curves in water and in urine were validated and statistically compared. This revealed the absence of matrix effect and, in consequence, the possibility of quantifying SSRI in urine samples by external water calibration. Intra-day and inter-day precision was satisfactory for all the target compounds (relative standard deviation, RSD, detection limits achieved were detected and tentatively identified.

Discovery of potent and selective CDK8 inhibitors through FBDD approach.

Science.gov (United States)

Han, Xingchun; Jiang, Min; Zhou, Chengang; Zhou, Zheng; Xu, Zhiheng; Wang, Lisha; Mayweg, Alexander V; Niu, Rui; Jin, Tai-Guang; Yang, Song

2017-09-15

A fragment library screen was carried out to identify starting points for novel CDK8 inhibitors. Optimization of a fragment hit guided by co-crystal structures led to identification of a novel series of potent CDK8 inhibitors which are highly ligand efficient, kinase selective and cellular active. Compound 16 was progressed to a mouse pharmacokinetic study and showed good oral bioavailability. Copyright © 2017 Elsevier Ltd. All rights reserved.

Nitrile in the Hole: Discovery of a Small Auxiliary Pocket in Neuronal Nitric Oxide Synthase Leading to the Development of Potent and Selective 2-Aminoquinoline Inhibitors.

Science.gov (United States)

Cinelli, Maris A; Li, Huiying; Chreifi, Georges; Poulos, Thomas L; Silverman, Richard B

2017-05-11

Neuronal nitric oxide synthase (nNOS) inhibition is a promising strategy to treat neurodegenerative disorders, but the development of nNOS inhibitors is often hindered by poor pharmacokinetics. We previously developed a class of membrane-permeable 2-aminoquinoline inhibitors and later rearranged the scaffold to decrease off-target binding. However, the resulting compounds had decreased permeability, low human nNOS activity, and low selectivity versus human eNOS. In this study, 5-substituted phenyl ether-linked aminoquinolines and derivatives were synthesized and assayed against purified NOS isoforms. 5-Cyano compounds are especially potent and selective rat and human nNOS inhibitors. Activity and selectivity are mediated by the binding of the cyano group to a new auxiliary pocket in nNOS. Potency was enhanced by methylation of the quinoline and by introduction of simple chiral moieties, resulting in a combination of hydrophobic and auxiliary pocket effects that yielded high (∼500-fold) n/e selectivity. Importantly, the Caco-2 assay also revealed improved membrane permeability over previous compounds.

Tricyclic GyrB/ParE (TriBE inhibitors: a new class of broad-spectrum dual-targeting antibacterial agents.

Directory of Open Access Journals (Sweden)

Leslie W Tari

Full Text Available Increasing resistance to every major class of antibiotics and a dearth of novel classes of antibacterial agents in development pipelines has created a dwindling reservoir of treatment options for serious bacterial infections. The bacterial type IIA topoisomerases, DNA gyrase and topoisomerase IV, are validated antibacterial drug targets with multiple prospective drug binding sites, including the catalytic site targeted by the fluoroquinolone antibiotics. However, growing resistance to fluoroquinolones, frequently mediated by mutations in the drug-binding site, is increasingly limiting the utility of this antibiotic class, prompting the search for other inhibitor classes that target different sites on the topoisomerase complexes. The highly conserved ATP-binding subunits of DNA gyrase (GyrB and topoisomerase IV (ParE have long been recognized as excellent candidates for the development of dual-targeting antibacterial agents with broad-spectrum potential. However, to date, no natural product or small molecule inhibitors targeting these sites have succeeded in the clinic, and no inhibitors of these enzymes have yet been reported with broad-spectrum antibacterial activity encompassing the majority of Gram-negative pathogens. Using structure-based drug design (SBDD, we have created a novel dual-targeting pyrimidoindole inhibitor series with exquisite potency against GyrB and ParE enzymes from a broad range of clinically important pathogens. Inhibitors from this series demonstrate potent, broad-spectrum antibacterial activity against Gram-positive and Gram-negative pathogens of clinical importance, including fluoroquinolone resistant and multidrug resistant strains. Lead compounds have been discovered with clinical potential; they are well tolerated in animals, and efficacious in Gram-negative infection models.

Low-dose aspirin, non-steroidal anti-inflammatory drugs, selective COX-2 inhibitors and breast cancer recurrence

DEFF Research Database (Denmark)

Cronin-Fenton, Deirdre P; Heide-Jørgensen, Uffe; Ahern, Thomas P

2016-01-01

BACKGROUND: Aspirin, nonsteroidal anti-inflammatory drugs (NSAIDs), and selective COX-2 inhibitors may improve outcomes in breast cancer patients. We investigated the association of aspirin, NSAIDs, and use of selective COX-2 inhibitors with breast cancer recurrence. METHODS: We identified incident...... stage I-III Danish breast cancer patients in the Danish Breast Cancer Cooperative Group registry, who were diagnosed during 1996-2008. Prescriptions for aspirin (>99% low-dose aspirin), NSAIDs, and selective COX-2 inhibitors were ascertained from the National Prescription Registry. Follow-up began....... RESULTS: We identified 34,188 breast cancer patients with 233,130 person-years of follow-up. Median follow-up was 7.1 years; 5,325 patients developed recurrent disease. Use of aspirin, NSAIDs, or selective COX-2 inhibitors was not associated with the rate of recurrence (HRadjusted aspirin = 1.0, 95% CI...

Selectivity criterion for pyrazolo[3,4-b]pyrid[az]ine derivatives as GSK-3 inhibitors: CoMFA and molecular docking studies.

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Patel, Dhilon S; Bharatam, Prasad V

2008-05-01

In the development of drugs targeted for GSK-3, its selective inhibition is an important requirement owing to the possibility of side effects arising from other kinases for the treatment of diabetes mellitus. A three-dimensional quantitative structure-activity relationship study (3D-QSAR) has been carried out on a set of pyrazolo[3,4-b]pyrid[az]ine derivatives, which includes non-selective and selective GSK-3 inhibitors. The CoMFA models were derived from a training set of 59 molecules. A test set containing 14 molecules (not used in model generation) was used to validate the CoMFA models. The best CoMFA model generated by applying leave-one-out (LOO) cross-validation study gave cross-validation r(cv)(2) and conventional r(conv)(2) values of 0.60 and 0.97, respectively, and r(pred)(2) value of 0.55, which provide the predictive ability of model. The developed models well explain (i) the observed variance in the activity and (ii) structural difference between the selective and non-selective GSK-3 inhibitors. Validation based on the molecular docking has also been carried out to explain the structural differences between the selective and non-selective molecules in the given series of molecules.

Selective phosphodiesterase inhibitors: a promising target for cognition enhancement

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Reneerkens, Olga A. H.; Rutten, Kris; Steinbusch, Harry W. M.; Blokland, Arjan; Prickaerts, Jos

2008-01-01

Rationale One of the major complaints most people face during aging is an impairment in cognitive functioning. This has a negative impact on the quality of daily life and is even more prominent in patients suffering from neurodegenerative and psychiatric disorders including Alzheimer?s disease, schizophrenia, and depression. So far, the majority of cognition enhancers are generally targeting one particular neurotransmitter system. However, recently phosphodiesterases (PDEs) have gained increa...

Identification of novel malarial cysteine protease inhibitors using structure-based virtual screening of a focused cysteine protease inhibitor library.

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Shah, Falgun; Mukherjee, Prasenjit; Gut, Jiri; Legac, Jennifer; Rosenthal, Philip J; Tekwani, Babu L; Avery, Mitchell A

2011-04-25

Malaria, in particular that caused by Plasmodium falciparum , is prevalent across the tropics, and its medicinal control is limited by widespread drug resistance. Cysteine proteases of P. falciparum , falcipain-2 (FP-2) and falcipain-3 (FP-3), are major hemoglobinases, validated as potential antimalarial drug targets. Structure-based virtual screening of a focused cysteine protease inhibitor library built with soft rather than hard electrophiles was performed against an X-ray crystal structure of FP-2 using the Glide docking program. An enrichment study was performed to select a suitable scoring function and to retrieve potential candidates against FP-2 from a large chemical database. Biological evaluation of 50 selected compounds identified 21 diverse nonpeptidic inhibitors of FP-2 with a hit rate of 42%. Atomic Fukui indices were used to predict the most electrophilic center and its electrophilicity in the identified hits. Comparison of predicted electrophilicity of electrophiles in identified hits with those in known irreversible inhibitors suggested the soft-nature of electrophiles in the selected target compounds. The present study highlights the importance of focused libraries and enrichment studies in structure-based virtual screening. In addition, few compounds were screened against homologous human cysteine proteases for selectivity analysis. Further evaluation of structure-activity relationships around these nonpeptidic scaffolds could help in the development of selective leads for antimalarial chemotherapy.

Preliminary in vitro and in vivo assessment of a new targeted inhibitor for choroidal neovascularization in age-related macular degeneration.

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Li, Wenbo; Dong, Lijie; Ma, Minwang; Hu, Bojie; Lu, Zhenyu; Liu, Xun; Liu, Juping; Li, Xiaorong

2016-01-01

Choroidal neovascularization (CNV) in age-related macular degeneration usually causes blindness. We established a novel targeted inhibitor for CNV in age-related macular degeneration. The inhibitor CR2-sFlt 1 comprises a CR2-targeting fragment and an anti-vascular endothelial growth factor (VEGF) domain (sFlt 1). The targeting of CR2-sFlt 1 was studied using the transwell assay in vitro and frozen sections in vivo using green fluorescent labeling. Transwell assay results showed that CR2-sFlt 1 migrated to the interface of complement activation products and was present in the retinal tissue of the CR2-sFlt 1-treated CNV mice. Treatment effects were assessed by investigating the VEGF concentration in retinal pigmented epithelial cell medium and the thickness of the CNV complex in the mice treated with CR2-sFlt 1. CR2-sFlt 1 significantly reduced the VEGF secretion from retinal pigmented epithelial cells in vitro and retarded CNV progress in a mouse model. Expression analysis of VEGF and VEGFRs after CR2-sFlt 1 intervention indicated the existence of feedback mechanisms in exogenous CR2-sFlt 1, endogenous VEGF, and VEGFR interaction. In summary, we demonstrated for the first time that using CR2-sFlt 1 could inhibit CNV with clear targeting and high selectivity.

Targeting Allostery with Avatars to Design Inhibitors Assessed by Cell Activity: Dissecting MRE11 Endo- and Exonuclease Activities.

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Moiani, Davide; Ronato, Daryl A; Brosey, Chris A; Arvai, Andrew S; Syed, Aleem; Masson, Jean-Yves; Petricci, Elena; Tainer, John A

2018-01-01

For inhibitor design, as in most research, the best system is question dependent. We suggest structurally defined allostery to design specific inhibitors that target regions beyond active sites. We choose systems allowing efficient quality structures with conformational changes as optimal for structure-based design to optimize inhibitors. We maintain that evolutionarily related targets logically provide molecular avatars, where this Sanskrit term for descent includes ideas of functional relationships and of being a physical embodiment of the target's essential features without requiring high sequence identity. Appropriate biochemical and cell assays provide quantitative measurements, and for biomedical impacts, any inhibitor's activity should be validated in human cells. Specificity is effectively shown empirically by testing if mutations blocking target activity remove cellular inhibitor impact. We propose this approach to be superior to experiments testing for lack of cross-reactivity among possible related enzymes, which is a challenging negative experiment. As an exemplary avatar system for protein and DNA allosteric conformational controls, we focus here on developing separation-of-function inhibitors for meiotic recombination 11 nuclease activities. This was achieved not by targeting the active site but rather by geometrically impacting loop motifs analogously to ribosome antibiotics. These loops are neighboring the dimer interface and active site act in sculpting dsDNA and ssDNA into catalytically competent complexes. One of our design constraints is to preserve DNA substrate binding to geometrically block competing enzymes and pathways from the damaged site. We validate our allosteric approach to controlling outcomes in human cells by reversing the radiation sensitivity and genomic instability in BRCA mutant cells. © 2018 Elsevier Inc. All rights reserved.

Nuclease Target Site Selection for Maximizing On-target Activity and Minimizing Off-target Effects in Genome Editing

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Lee, Ciaran M; Cradick, Thomas J; Fine, Eli J; Bao, Gang

2016-01-01

The rapid advancement in targeted genome editing using engineered nucleases such as ZFNs, TALENs, and CRISPR/Cas9 systems has resulted in a suite of powerful methods that allows researchers to target any genomic locus of interest. A complementary set of design tools has been developed to aid researchers with nuclease design, target site selection, and experimental validation. Here, we review the various tools available for target selection in designing engineered nucleases, and for quantifying nuclease activity and specificity, including web-based search tools and experimental methods. We also elucidate challenges in target selection, especially in predicting off-target effects, and discuss future directions in precision genome editing and its applications. PMID:26750397

High-throughput screening identifies Ceefourin 1 and Ceefourin 2 as highly selective inhibitors of multidrug resistance protein 4 (MRP4).

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Cheung, Leanna; Flemming, Claudia L; Watt, Fujiko; Masada, Nanako; Yu, Denise M T; Huynh, Tony; Conseil, Gwenaëlle; Tivnan, Amanda; Polinsky, Alexander; Gudkov, Andrei V; Munoz, Marcia A; Vishvanath, Anasuya; Cooper, Dermot M F; Henderson, Michelle J; Cole, Susan P C; Fletcher, Jamie I; Haber, Michelle; Norris, Murray D

2014-09-01

Multidrug resistance protein 4 (MRP4/ABCC4), a member of the ATP-binding cassette (ABC) transporter superfamily, is an organic anion transporter capable of effluxing a wide range of physiologically important signalling molecules and drugs. MRP4 has been proposed to contribute to numerous functions in both health and disease; however, in most cases these links remain to be unequivocally established. A major limitation to understanding the physiological and pharmacological roles of MRP4 has been the absence of specific small molecule inhibitors, with the majority of established inhibitors also targeting other ABC transporter family members, or inhibiting the production, function or degradation of important MRP4 substrates. We therefore set out to identify more selective and well tolerated inhibitors of MRP4 that might be used to study the many proposed functions of this transporter. Using high-throughput screening, we identified two chemically distinct small molecules, Ceefourin 1 and Ceefourin 2, that inhibit transport of a broad range of MRP4 substrates, yet are highly selective for MRP4 over other ABC transporters, including P-glycoprotein (P-gp), ABCG2 (Breast Cancer Resistance Protein; BCRP) and MRP1 (multidrug resistance protein 1; ABCC1). Both compounds are more potent MRP4 inhibitors in cellular assays than the most widely used inhibitor, MK-571, requiring lower concentrations to effect a comparable level of inhibition. Furthermore, Ceefourin 1 and Ceefourin 2 have low cellular toxicity, and high microsomal and acid stability. These newly identified inhibitors should be of great value for efforts to better understand the biological roles of MRP4, and may represent classes of compounds with therapeutic application. Copyright © 2014 Elsevier Inc. All rights reserved.

The kidney as a new target for antidiabetic drugs: SGLT2 inhibitors.

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Cangoz, S; Chang, Y-Y; Chempakaseril, S J; Guduru, R C; Huynh, L M; John, J S; John, S T; Joseph, M E; Judge, R; Kimmey, R; Kudratov, K; Lee, P J; Madhani, I C; Shim, P J; Singh, S; Singh, S; Ruchalski, C; Raffa, R B

2013-10-01

A novel class of antidiabetic drugs - SGLT2 (Na(+) /glucose cotransporter type 2) inhibitors - target renal reabsorption of glucose and promote normal glucose levels, independent of insulin production or its action at receptors. We review this new mechanistic approach and the reported efficacy and safety of clinical testing of lead compounds. Information was obtained from various bibliographic sources, including PubMed and others, on the basic science and the clinical trials of SGLT2 inhibitors. The information was then summarized and evaluated from the perspective of contribution to a fuller understanding of the potential and current status of the lead clinical candidates. Diabetes mellitus is a spectrum of disorders that involves inadequate insulin function resulting in adverse health sequelae due to acute and chronic hyperglycaemia. Current antidiabetic pharmacotherapy primarily addresses either insulin production at the pancreatic β-cells or insulin action at insulin receptors. These drugs have less than full clinical effectiveness and sometimes therapy-limiting adverse effects. The third major component of glucose balance, namely elimination, has not been a significant therapeutic target to date. SGLT2 inhibitors are a novel approach. A sufficient number of clinical trials have been conducted on sufficiently chemically diverse SGLT2 inhibitors to reasonably conclude that they have efficacy (HbA1c reductions of 0·4-1%), and thus far, the majority of adverse effects have been mild and transitory or treatable, with the caveat of possible association with increased risk of breast cancer in women and bladder cancer in men. © 2013 John Wiley & Sons Ltd.

Reversible targeting of noncatalytic cysteines with chemically tuned electrophiles

DEFF Research Database (Denmark)

Serafimova, Iana M; Pufall, Miles A; Krishnan, Shyam

2012-01-01

Targeting noncatalytic cysteine residues with irreversible acrylamide-based inhibitors is a powerful approach for enhancing pharmacological potency and selectivity. Nevertheless, concerns about off-target modification motivate the development of reversible cysteine-targeting strategies. Here we...... of these electrophiles into a noncovalent kinase-recognition scaffold produced slowly dissociating, covalent inhibitors of the p90 ribosomal protein S6 kinase RSK2. A cocrystal structure revealed specific noncovalent interactions that stabilize the complex by positioning the electrophilic carbon near the targeted...

Selective mGAT2 (BGT-1) GABA Uptake Inhibitor

DEFF Research Database (Denmark)

Vogensen, Stine Byskov; Jørgensen, Lars; Madsen, Karsten Kirkegaard

2013-01-01

β-Amino acids sharing a lipophilic diaromatic side chain were synthesized and characterized pharmacologically on mouse GABA transporter subtypes mGAT1−4. The parent amino acids were also characterized. Compounds 13a, 13b, and 17b displayed more than 6-fold selectivity for mGAT2 over mGAT1. Compou...... 17b displayed anticonvulsive properties inferring a role of mGAT2 in epileptic disorders. These results provide new neuropharmacological tools and a strategy for designing subtype selective GABA transport inhibitors....

The Design of New HIV-IN Tethered Bifunctional Inhibitors using Multiple Microdomain Targeted Docking.

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Ciubotaru, Mihai; Musat, Mihaela Georgiana; Surleac, Marius; Ionita, Elena; Petrescu, Andrei Jose; Abele, Edgars; Abele, Ramona

2018-04-05

Currently used antiretroviral HIV therapy drugs exclusively target critical groups in the enzymes essential for the viral life cycle. Increased mutagenesis of their genes, changes these viral enzymes which once mutated can evade therapeutic targeting, effects which confer drug resistance. To circumvent this, our review addresses a strategy to design and derive HIV-Integrase (HIV-IN) inhibitors which simultaneously target two IN functional domains, rendering it inactive even if the enzyme accumulates many mutations. First we review the enzymatic role of IN to insert the copied viral DNA into a chromosome of the host T lymphocyte, highlighting its main functional and structural features to be subjected to inhibitory action. From a functional and structural perspective we present all classes of HIV-IN inhibitors with their most representative candidates. For each chosen compound we also explain its mechanism of IN inhibition. We use the recently resolved cryo EM IN tetramer intasome DNA complex [1] onto which we dock various reference IN inhibitory chemical scaffolds such as to target adjacent functional IN domains. Pairing compounds with complementary activity, which dock in the vicinity of a IN structural microdomain, we design bifunctional new drugs which may not only be more resilient to IN mutations but also may be more potent inhibitors than their original counterparts. In the end of our review we propose synthesis pathways to link such paired compounds with enhanced synergistic IN inhibitory effects. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Structure-Based Design and Synthesis of Potent and Selective Matrix Metalloproteinase 13 Inhibitors.

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Choi, Jun Yong; Fuerst, Rita; Knapinska, Anna M; Taylor, Alexander B; Smith, Lyndsay; Cao, Xiaohang; Hart, P John; Fields, Gregg B; Roush, William R

2017-07-13

We describe the use of comparative structural analysis and structure-guided molecular design to develop potent and selective inhibitors (10d and (S)-17b) of matrix metalloproteinase 13 (MMP-13). We applied a three-step process, starting with a comparative analysis of the X-ray crystallographic structure of compound 5 in complex with MMP-13 with published structures of known MMP-13·inhibitor complexes followed by molecular design and synthesis of potent but nonselective zinc-chelating MMP inhibitors (e.g., 10a and 10b). After demonstrating that the pharmacophores of the chelating inhibitors (S)-10a, (R)-10a, and 10b were binding within the MMP-13 active site, the Zn 2+ chelating unit was replaced with nonchelating polar residues that bridged over the Zn 2+ binding site and reached into a solvent accessible area. After two rounds of structural optimization, these design approaches led to small molecule MMP-13 inhibitors 10d and (S)-17b, which bind within the substrate-binding site of MMP-13 and surround the catalytically active Zn 2+ ion without chelating to the metal. These compounds exhibit at least 500-fold selectivity versus other MMPs.

Discovery and development of inhibitors selective for human constitutive proteasome and immunoproteasome active sites

NARCIS (Netherlands)

Xin, B.

2017-01-01

This thesis describes the design and development of subunit‐selective inhibitors of particular catalytically active subunits of human constitutive proteasomes and immunoproteasomes. Most existing proteasome inhibitors are oligopeptides composed of 2‐4 amino acid residues, N‐terminally

Structure-Guided Strategy for the Development of Potent Bivalent ERK Inhibitors

Energy Technology Data Exchange (ETDEWEB)

Lechtenberg, Bernhard C. [Cancer; Mace, Peter D. [Cancer; Sessions, E. Hampton [Sanford Burnham Prebys Medical Discovery Institute at Lake Nona, Orlando, Florida 32827, United States; Williamson, Robert [Sanford Burnham Prebys Medical Discovery Institute at Lake Nona, Orlando, Florida 32827, United States; Stalder, Romain [Sanford Burnham Prebys Medical Discovery Institute at Lake Nona, Orlando, Florida 32827, United States; Wallez, Yann [Cancer; Roth, Gregory P. [Sanford Burnham Prebys Medical Discovery Institute at Lake Nona, Orlando, Florida 32827, United States; Riedl, Stefan J. [Cancer; Pasquale, Elena B. [Cancer; Pathology

2017-06-13

ERK is the effector kinase of the RAS-RAF-MEK-ERK signaling cascade, which promotes cell transformation and malignancy in many cancers and is thus a major drug target in oncology. Kinase inhibitors targeting RAF or MEK are already used for the treatment of certain cancers, such as melanoma. Although the initial response to these drugs can be dramatic, development of drug resistance is a major challenge, even with combination therapies targeting both RAF and MEK. Importantly, most resistance mechanisms still rely on activation of the downstream effector kinase ERK, making it a promising target for drug development efforts. Here, we report the design and structural/functional characterization of a set of bivalent ERK inhibitors that combine a small molecule inhibitor that binds to the ATP-binding pocket with a peptide that selectively binds to an ERK protein interaction surface, the D-site recruitment site (DRS). Our studies show that the lead bivalent inhibitor, SBP3, has markedly improved potency compared to the small molecule inhibitor alone. Unexpectedly, we found that SBP3 also binds to several ERK-related kinases that contain a DRS, highlighting the importance of experimentally verifying the predicted specificity of bivalent inhibitors. However, SBP3 does not target any other kinases belonging to the same CMGC branch of the kinome. Additionally, our modular click chemistry inhibitor design facilitates the generation of different combinations of small molecule inhibitors with ERK-targeting peptides.

Cell-Specific Establishment of Poliovirus Resistance to an Inhibitor Targeting a Cellular Protein

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Viktorova, Ekaterina G.; Nchoutmboube, Jules; Ford-Siltz, Lauren A.

2015-01-01

ABSTRACT It is hypothesized that targeting stable cellular factors involved in viral replication instead of virus-specific proteins may raise the barrier for development of resistant mutants, which is especially important for highly adaptable small (+)RNA viruses. However, contrary to this assumption, the accumulated evidence shows that these viruses easily generate mutants resistant to the inhibitors of cellular proteins at least in some systems. We investigated here the development of poliovirus resistance to brefeldin A (BFA), an inhibitor of the cellular protein GBF1, a guanine nucleotide exchange factor for the small cellular GTPase Arf1. We found that while resistant viruses can be easily selected in HeLa cells, they do not emerge in Vero cells, in spite that in the absence of the drug both cultures support robust virus replication. Our data show that the viral replication is much more resilient to BFA than functioning of the cellular secretory pathway, suggesting that the role of GBF1 in the viral replication is independent of its Arf activating function. We demonstrate that the level of recruitment of GBF1 to the replication complexes limits the establishment and expression of a BFA resistance phenotype in both HeLa and Vero cells. Moreover, the BFA resistance phenotype of poliovirus mutants is also cell type dependent in different cells of human origin and results in a fitness loss in the form of reduced efficiency of RNA replication in the absence of the drug. Thus, a rational approach to the development of host-targeting antivirals may overcome the superior adaptability of (+)RNA viruses. IMPORTANCE Compared to the number of viral diseases, the number of available vaccines is miniscule. For some viruses vaccine development has not been successful after multiple attempts, and for many others vaccination is not a viable option. Antiviral drugs are needed for clinical practice and public health emergencies. However, viruses are highly adaptable and can

Structure-Based Design of Potent and Selective 3-Phosphoinositide-Dependent Kinase-1 (PDK1) Inhibitors

Energy Technology Data Exchange (ETDEWEB)

Medina, Jesus R.; Becker, Christopher J.; Blackledge, Charles W.; Duquenne, Celine; Feng, Yanhong; Grant, Seth W.; Heerding, Dirk; Li, William H.; Miller, William H.; Romeril, Stuart P.; Scherzer, Daryl; Shu, Arthur; Bobko, Mark A.; Chadderton, Antony R.; Dumble, Melissa; Gardiner, Christine M.; Gilbert, Seth; Liu, Qi; Rabindran, Sridhar K.; Sudakin, Valery; Xiang, Hong; Brady, Pat G.; Campobasso, Nino; Ward, Paris; Axten, Jeffrey M. (GSKPA)

2014-10-02

Phosphoinositide-dependent protein kinase-1(PDK1) is a master regulator of the AGC family of kinases and an integral component of the PI3K/AKT/mTOR pathway. As this pathway is among the most commonly deregulated across all cancers, a selective inhibitor of PDK1 might have utility as an anticancer agent. Herein we describe our lead optimization of compound 1 toward highly potent and selective PDK1 inhibitors via a structure-based design strategy. The most potent and selective inhibitors demonstrated submicromolar activity as measured by inhibition of phosphorylation of PDK1 substrates as well as antiproliferative activity against a subset of AML cell lines. In addition, reduction of phosphorylation of PDK1 substrates was demonstrated in vivo in mice bearing OCl-AML2 xenografts. These observations demonstrate the utility of these molecules as tools to further delineate the biology of PDK1 and the potential pharmacological uses of a PDK1 inhibitor.

Development of antibody-based c-Met inhibitors for targeted cancer therapy

Directory of Open Access Journals (Sweden)

Lee D

2015-02-01

Full Text Available Dongheon Lee, Eun-Sil Sung, Jin-Hyung Ahn, Sungwon An, Jiwon Huh, Weon-Kyoo You Hanwha Chemical R&D Center, Biologics Business Unit, Daejeon, Republic of Korea Abstract: Signaling pathways mediated by receptor tyrosine kinases (RTKs and their ligands play important roles in the development and progression of human cancers, which makes RTK-mediated signaling pathways promising therapeutic targets in the treatment of cancer. Compared with small-molecule compounds, antibody-based therapeutics can more specifically recognize and bind to ligands and RTKs. Several antibody inhibitors of RTK-mediated signaling pathways, such as human epidermal growth factor receptor 2, vascular endothelial growth factor, epidermal growth factor receptor or vascular endothelial growth factor receptor 2, have been developed and are widely used to treat cancer patients. However, since the therapeutic options are still limited in terms of therapeutic efficacy and types of cancers that can be treated, efforts are being made to identify and evaluate novel RTK-mediated signaling pathways as targets for more efficacious cancer treatment. The hepatocyte growth factor/c-Met signaling pathway has come into the spotlight as a promising target for development of potent cancer therapeutic agents. Multiple antibody-based therapeutics targeting hepatocyte growth factor or c-Met are currently in preclinical or clinical development. This review focuses on the development of inhibitors of the hepatocyte growth factor/c-Met signaling pathway for cancer treatment, including critical issues in clinical development and future perspectives for antibody-based therapeutics. Keywords: hepatocyte growth factor, ligands, receptor tyrosine kinase, signaling pathway, therapeutic agent

3,4-Dimethoxyphenyl bis-benzimidazole, a novel DNA topoisomerase inhibitor that preferentially targets Escherichia coli topoisomerase I

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Bansal, Sandhya; Sinha, Devapriya; Singh, Manish; Cheng, Bokun; Tse-Dinh, Yuk-Ching; Tandon, Vibha

2012-01-01

Objectives Antibiotic resistance in bacterial pathogens is a serious clinical problem. Novel targets are needed to combat increasing drug resistance in Escherichia coli. Our objective is to demonstrate that 2-(3,4-dimethoxyphenyl)-5-[5-(4-methylpiperazin-1-yl)-1H-benzimidazol-2yl]-1H-benzimidazole (DMA) inhibits E. coli DNA topoisomerase I more strongly than human topoisomerase I. In addition, DMA is non-toxic to mammalian cells at antibiotic dosage level. Methods In the present study, we have established DMA as an antibacterial compound by determining MICs, post-antibiotic effects (PAEs) and MBCs for different standard as well as clinical strains of E. coli. We have described the differential catalytic inhibitory mechanism of bis-benzimidazole, DMA, for human and E. coli topoisomerase I and topoisomerase II by performing different assays, including relaxation assays, cleavage–religation assays, DNA unwinding assays, ethidium bromide displacement assays, decatenation assays and DNA gyrase supercoiling assays. Results DMA significantly inhibited bacterial growth at a very low concentration, but did not affect human cell viability at higher concentrations. Activity assays showed that it preferentially targeted E. coli topoisomerase I over human topoisomerase I, topoisomerase II and gyrase. Cleavage–religation assays confirmed DMA as a poison inhibitor of E. coli topoisomerase I. This study illuminates new properties of DMA, which may be further modified to develop an efficient topoisomerase inhibitor that is selective towards bacterial topoisomerase I. Conclusions This is the first report of a bis-benzimidazole acting as an E. coli topoisomerase I inhibitor. DMA is a safe, non-cytotoxic molecule to human cells at concentrations that are needed for antibacterial activity. PMID:22945915

Small Molecule Inhibitors in Acute Myeloid Leukemia: From the Bench to the Clinic

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Al-Hussaini, Muneera; DiPersio, John F.

2014-01-01

Many patients with acute myeloid leukemia (AML) will eventually develop refractory or relapsed disease. In the absence of standard therapy for this population, there is currently an urgent unmet need for novel therapeutic agents. Targeted therapy with small molecule inhibitors (SMIs) represents a new therapeutic intervention that has been successful for the treatment of multiple tumors (e.g., gastrointestinal stromal tumors, chronic myelogenous leukemia). Hence, there has been great interest in generating selective small molecule inhibitors targeting critical pathways of proliferation and survival in AML. This review highlights a selective group of intriguing therapeutic agents and their presumed targets in both preclinical models and in early human clinical trials. PMID:25025370

Fragment-based design of symmetrical bis-benzimidazoles as selective inhibitors of the trimethoprim-resistant, type II R67 dihydrofolate reductase.

Science.gov (United States)

Bastien, Dominic; Ebert, Maximilian C C J C; Forge, Delphine; Toulouse, Jacynthe; Kadnikova, Natalia; Perron, Florent; Mayence, Annie; Huang, Tien L; Vanden Eynde, Jean Jacques; Pelletier, Joelle N

2012-04-12

The continuously increasing use of trimethoprim as a common antibiotic for medical use and for prophylactic application in terrestrial and aquatic animal farming has increased its prevalence in the environment. This has been accompanied by increased drug resistance, generally in the form of alterations in the drug target, dihydrofolate reductase (DHFR). The most highly resistant variants of DHFR are known as type II DHFR, among which R67 DHFR is the most broadly studied variant. We report the first attempt at designing specific inhibitors to this emerging drug target by fragment-based design. The detection of inhibition in R67 DHFR was accompanied by parallel monitoring of the human DHFR, as an assessment of compound selectivity. By those means, small aromatic molecules of 150-250 g/mol (fragments) inhibiting R67 DHFR selectively in the low millimolar range were identified. More complex, symmetrical bis-benzimidazoles and a bis-carboxyphenyl were then assayed as fragment-based leads, which procured selective inhibition of the target in the low micromolar range (K(i) = 2-4 μM). The putative mode of inhibition is discussed according to molecular modeling supported by in vitro tests. © 2012 American Chemical Society

Discovery of amido-benzisoxazoles as potent c-Kit inhibitors

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Kunz, Roxanne K.; Rumfelt, Shannon; Chen, Ning; Zhang, Dawei; Tasker, Andrew S.; Bürli, Roland; Hungate, Randall; Yu, Violeta; Nguyen, Yen; Whittington, Douglas A.; Meagher, Kristin L.; Plant, Matthew; Tudor, Yanyan; Schrag, Michael; Xu, Yang; Ng, Gordon Y.; Hu, Essa (Amgen)

2010-01-12

Deregulation of the receptor tyrosine kinase c-Kit is associated with an increasing number of human diseases, including certain cancers and mast cell diseases. Interference of c-Kit signaling with multi-kinase inhibitors has been shown clinically to successfully treat gastrointestinal stromal tumors and mastocytosis. Targeted therapy of c-Kit activity may provide therapeutic advantages against off-target effects for non-oncology applications. A new structural class of c-Kit inhibitors is described, including in vitro c-Kit potency, kinase selectivity, and the observed binding mode.

The selectivity and promiscuity of brain-neuroregenerative inhibitors between ROCK1 and ROCK2 isoforms: An integration of SB-QSSR modelling, QM/MM analysis and in vitro kinase assay.

Science.gov (United States)

Zhu, L; Yang, Y; Lu, X

2016-01-01

The Rho-associated kinases (ROCKs) have long been recognized as an attractive therapeutic target for various neurological diseases; selective inhibition of ROCK1 and ROCK2 isoforms would result in distinct biological effects on neurogenesis, neuroplasticity and neuroregeneration after brain surgery and traumatic brain injury. However, the discovery and design of isoform-selective inhibitors remain a great challenge due to the high conservation and similarity between the kinase domains of ROCK1 and ROCK2. Here, a structure-based quantitative structure-selectivity relationship (SB-QSSR) approach was used to correlate experimentally measured selectivity with the difference in inhibitor binding to the two kinase isoforms. The resulting regression models were examined rigorously through both internal cross-validation and external blind validation; a nonlinear predictor was found to have high fitting stability and strong generalization ability, which was then employed to perform virtual screening against a structurally diverse, drug-like compound library. Consequently, five and seven hits were identified as promising candidates of 1-o-2 and 2-o-1 selective inhibitors, respectively, from which seven purchasable compounds were tested in vitro using a standard kinase assay protocol to determine their inhibitory activity against and selectivity between ROCK1 and ROCK2. The structural basis, energetic property and biological implication underlying inhibitor selectivity and promiscuity were also investigated systematically using a hybrid quantum mechanics/molecular mechanics (QM/MM) scheme.

Mechanism-based PK/PD modeling of selective serotonin reuptake inhibitors

NARCIS (Netherlands)

Geldof, Marian

2007-01-01

The main objective of the investigations was to explore the PK/PD correlations of fluvoxamine, as a prototype for the Selective Serotonin Reuptake Inhibitors (SSRIs). In the various investigations, a spectrum of different biomarkers was used, each reflecting a specific process on the causal path

A combination of SILAC and nucleotide acyl phosphate labelling reveals unexpected targets of the Rsk inhibitor BI-D1870.

Science.gov (United States)

Edgar, Alexander J; Trost, Matthias; Watts, Colin; Zaru, Rossana

2014-02-01

Protein kinase inhibitors frequently have interesting effects that cannot be fully ascribed to the intended target kinase(s) but identifying additional targets that might explain the effects is not straightforward. By comparing two different inhibitors of the Rsk (p90 ribosomal S6 kinase) kinases, we found that the increasingly used compound BI-D1870 had biological effects in murine DCs (dendritic cells) that could not be solely ascribed to Rsk or other documented targets. We assessed the ability of BI-D1870 and a second Rsk inhibitor, BIX 02565 to protect enzyme active sites from reaction with biotinylated nucleotide acyl phosphates. Using SILAC (stable isotope labelling by amino acids in cell culture)-labelled DC lysates as a source of enzyme targets, we identify several kinases that interact with BI-D1870 but not with BIX 02565. We confirmed that these kinases, including Slk, Lok and Mst1, are inhibited by BI-D1870 but to a much lesser extent by BIX 02565 and that phosphorylation of some of their substrates is blocked by BI-D1870 in living cells. Our results suggest that the BI-D1870 inhibitor should be used with caution. The SILAC-based methodology we used should be useful for further comparative unbiased profiling of the target spectrum of kinase inhibitors with interesting biological effects under conditions that closely mimic those found in cells. © 2014 The author(s).

Design, Synthesis and Biological Evaluation of Novel Benzothiazole Derivatives as Selective PI3Kβ Inhibitors

Directory of Open Access Journals (Sweden)

Shuang Cao

2016-07-01

Full Text Available A novel series of PI3Kβ (Phosphatidylinositol-3-kinases beta subunit inhibitors with the structure of benzothiazole scaffold have been designed and synthesized. All the compounds have been evaluated for inhibitory activities against PI3Kα, β, γ, δ and mTOR (Mammalian target of rapamycin. Two superior compounds have been further evaluated for the IC50 values against PI3Ks/mTOR. The most promising compound 11 displays excellent anti-proliferative activity and selectivity in multiple cancer cell lines, especially in the prostate cancer cell line. Docking studies indicate the morpholine group in 2-position of benzothiazole is necessary for the potent antitumor activity, which confirms our design is reasonable.

Selection of flowing liquid lead target structural materials for accelerator driven transmutation applications

International Nuclear Information System (INIS)

Park, J.J.; Buksa, J.J.

1994-01-01

The beam entry window and container for a liquid lead spallation target will be exposed to high fluxes of protons and neutrons that are both higher in magnitude and energy than have been experienced in proton accelerators and fission reactors, as well as in a corrosive environment. The structural material of the target should have a good compatibility with liquid lead, a sufficient mechanical strength at elevated temperatures, a good performance under an intense irradiation environment, and a low neutron absorption cross section; these factors have been used to rank the applicability of a wide range of materials for structural containment Nb-1Zr has been selected for use as the structural container for the LANL ABC/ATW molten lead target. Corrosion and mass transfer behavior for various candidate structural materials in liquid lead are reviewed, together with the beneficial effects of inhibitors and various coatings to protect substrate against liquid lead corrosion. Mechanical properties of some candidate materials at elevated temperatures and the property changes resulting from 800 MeV proton irradiation are also reviewed

The 'retro-design' concept for novel kinase inhibitors.

Science.gov (United States)

Müller, Gerhard; Sennhenn, Peter C; Woodcock, Timothy; Neumann, Lars

2010-07-01

Protein kinases are among the most attractive therapeutic targets for a broad range of diseases. This feature review highlights and classifies the main design principles employed to generate active and selective kinase inhibitors. In particular, emphasis is focused on a fragment-based lead-generation approach, which constitutes a novel design method for developing type II kinase inhibitors with distinct binding kinetic attributes. This 'retro-design' strategy relies on a customized fragment library, and contrasts the traditional approach used in the design of type II inhibitors.

Immune checkpoint inhibitors and targeted therapies for metastatic melanoma: A network meta-analysis.

Science.gov (United States)

Pasquali, Sandro; Chiarion-Sileni, Vanna; Rossi, Carlo Riccardo; Mocellin, Simone

2017-03-01

Immune checkpoint inhibitors and targeted therapies, two new class of drugs for treatment of metastatic melanoma, have not been compared in randomized controlled trials (RCT). We quantitatively summarized the evidence and compared immune and targeted therapies in terms of both efficacy and toxicity. A comprehensive search for RCTs of immune checkpoint inhibitors and targeted therapies was conducted to August 2016. Using a network meta-analysis approach, treatments were compared with each other and ranked based on their effectiveness (as measured by the impact on progression-free survival [PFS]) and acceptability (the inverse of high grade toxicity). Twelve RCTs enrolling 6207 patients were included. Network meta-analysis generated 15 comparisons. Combined BRAF and MEK inhibitors were associated with longer PFS as compared to anti-CTLA4 (HR: 0.22; 95% confidence interval [CI]: 0.12-0.41) and anti-PD1 antibodies alone (HR: 0.38; CI: 0.20-0.72). However, anti-PD1 monoclonal antibodies were less toxic than anti-CTLA4 monoclonal antibodies (RR: 0.65; CI: 0.40-0.78) and their combination significantly increased toxicity compared to either single agent anti-CTLA4 (RR: 2.06; CI: 1.45-2.93) or anti-PD1 monoclonal antibodies (RR: 3.67; CI: 2.27-5.96). Consistently, ranking analysis suggested that the combination of targeted therapies is the most effective strategy, whereas single agent anti-PD1 antibodies have the best acceptability. The GRADE level of evidence quality for these findings was moderate to low. The simultaneous inhibition of BRAF and MEK appears the most effective treatment for melanomas harboring BRAF V600 mutation, although anti-PD1 antibodies appear to be less toxic. Further research is needed to increase the quality of evidence. Copyright © 2017 Elsevier Ltd. All rights reserved.

Virtual screening for potential inhibitors of bacterial MurC and MurD ligases.

Science.gov (United States)

Tomašić, Tihomir; Kovač, Andreja; Klebe, Gerhard; Blanot, Didier; Gobec, Stanislav; Kikelj, Danijel; Mašič, Lucija Peterlin

2012-03-01

Mur ligases are bacterial enzymes involved in the cytoplasmic steps of peptidoglycan biosynthesis and are viable targets for antibacterial drug discovery. We have performed virtual screening for potential ATP-competitive inhibitors targeting MurC and MurD ligases, using a protocol of consecutive hierarchical filters. Selected compounds were evaluated for inhibition of MurC and MurD ligases, and weak inhibitors possessing dual inhibitory activity have been identified. These compounds represent new scaffolds for further optimisation towards multiple Mur ligase inhibitors with improved inhibitory potency.

Selecting Therapeutic Targets in Inflammatory Bowel Disease (STRIDE)

DEFF Research Database (Denmark)

Peyrin-Biroulet, L; Sandborn, W; Sands, B E

2015-01-01

OBJECTIVES: The Selecting Therapeutic Targets in Inflammatory Bowel Disease (STRIDE) program was initiated by the International Organization for the Study of Inflammatory Bowel Diseases (IOIBD). It examined potential treatment targets for inflammatory bowel disease (IBD) to be used for a "treat-t...... target. CONCLUSIONS: Evidence- and consensus-based recommendations for selecting the goals for treat-to-target strategies in patients with IBD are made available. Prospective studies are needed to determine how these targets will change disease course and patients' quality of life....

Dependence and withdrawal reactions to benzodiazepines and selective serotonin reuptake inhibitors. How did the health authorities react?

DEFF Research Database (Denmark)

Nielsen, Margrethe; Hansen, Ebba Holme; Gøtzsche, Peter C

2013-01-01

Our objective was to explore communications from drug agencies about benzodiazepine dependence and selective serotonin reuptake inhibitors (SSRIs) withdrawal reactions over time.......Our objective was to explore communications from drug agencies about benzodiazepine dependence and selective serotonin reuptake inhibitors (SSRIs) withdrawal reactions over time....

Use of selective serotonin reuptake inhibitors reduces fertility in men

DEFF Research Database (Denmark)

Nørr, L; Bennedsen, Birgit; Fedder, Jens

2016-01-01

Clinical review of the present data on the effects of selective serotonin reuptake inhibitors (SSRIs) on male fertility was the objective of the study. PubMed and Scopus were searched for publications in English or Danish and reviewed. Human trials, animal studies and in vitro studies were included...

Selective kallikrein inhibitors alter human neutrophil elastase release during extracorporeal circulation

NARCIS (Netherlands)

Wachtfogel, Y.T.; Hack, C.E.; Nuijens, J.H; Kettner, C.; Reilly, T.M.; Knabb, R.M.; Bischoff, Rainer; Tschesche, H.; Wenzel, H.; Kucich, U.

1995-01-01

Cardiopulmonary bypass causes hemorrhagic complications and initiates a biochemical and cellular "whole body inflammatory response." This study investigates whether a variety of selective inhibitors of the contact pathway of intrinsic coagulation modulate complement and neutrophil activation during

Identification of human triple-negative breast cancer subtypes and preclinical models for selection of targeted therapies

Science.gov (United States)

Lehmann, Brian D.; Bauer, Joshua A.; Chen, Xi; Sanders, Melinda E.; Chakravarthy, A. Bapsi; Shyr, Yu; Pietenpol, Jennifer A.

2011-01-01

Triple-negative breast cancer (TNBC) is a highly diverse group of cancers, and subtyping is necessary to better identify molecular-based therapies. In this study, we analyzed gene expression (GE) profiles from 21 breast cancer data sets and identified 587 TNBC cases. Cluster analysis identified 6 TNBC subtypes displaying unique GE and ontologies, including 2 basal-like (BL1 and BL2), an immunomodulatory (IM), a mesenchymal (M), a mesenchymal stem–like (MSL), and a luminal androgen receptor (LAR) subtype. Further, GE analysis allowed us to identify TNBC cell line models representative of these subtypes. Predicted “driver” signaling pathways were pharmacologically targeted in these cell line models as proof of concept that analysis of distinct GE signatures can inform therapy selection. BL1 and BL2 subtypes had higher expression of cell cycle and DNA damage response genes, and representative cell lines preferentially responded to cisplatin. M and MSL subtypes were enriched in GE for epithelial-mesenchymal transition, and growth factor pathways and cell models responded to NVP-BEZ235 (a PI3K/mTOR inhibitor) and dasatinib (an abl/src inhibitor). The LAR subtype includes patients with decreased relapse-free survival and was characterized by androgen receptor (AR) signaling. LAR cell lines were uniquely sensitive to bicalutamide (an AR antagonist). These data may be useful in biomarker selection, drug discovery, and clinical trial design that will enable alignment of TNBC patients to appropriate targeted therapies. PMID:21633166

Urea transporter proteins as targets for small-molecule diuretics.

Science.gov (United States)

Esteva-Font, Cristina; Anderson, Marc O; Verkman, Alan S

2015-02-01

Conventional diuretics such as furosemide and thiazides target salt transporters in kidney tubules, but urea transporters (UTs) have emerged as alternative targets. UTs are a family of transmembrane channels expressed in a variety of mammalian tissues, in particular the kidney. UT knockout mice and humans with UT mutations exhibit reduced maximal urinary osmolality, demonstrating that UTs are necessary for the concentration of urine. Small-molecule screening has identified potent and selective inhibitors of UT-A, the UT protein expressed in renal tubule epithelial cells, and UT-B, the UT protein expressed in vasa recta endothelial cells. Data from UT knockout mice and from rodents administered UT inhibitors support the diuretic action of UT inhibition. The kidney-specific expression of UT-A1, together with high selectivity of the small-molecule inhibitors, means that off-target effects of such small-molecule drugs should be minimal. This Review summarizes the structure, expression and function of UTs, and looks at the evidence supporting the validity of UTs as targets for the development of salt-sparing diuretics with a unique mechanism of action. UT-targeted inhibitors may be useful alone or in combination with conventional diuretics for therapy of various oedemas and hyponatraemias, potentially including those refractory to treatment with current diuretics.

Imidazopyridine derivatives as potent and selective Polo-like kinase (PLK) inhibitors.

Science.gov (United States)

Sato, Yoshiyuki; Onozaki, Yu; Sugimoto, Tetsuya; Kurihara, Hideki; Kamijo, Kaori; Kadowaki, Chie; Tsujino, Toshiaki; Watanabe, Akiko; Otsuki, Sachie; Mitsuya, Morihiro; Iida, Masato; Haze, Kyosuke; Machida, Takumitsu; Nakatsuru, Yoko; Komatani, Hideya; Kotani, Hidehito; Iwasawa, Yoshikazu

2009-08-15

A novel class of imidazopyridine derivatives was designed as PLK1 inhibitors. Extensive SAR studies supported by molecular modeling afforded a highly potent and selective compound 36. Compound 36 demonstrated good antitumor efficacy in xenograft nude rat model.

Discovery of novel high potent and cellular active ADC type PTP1B inhibitors with selectivity over TC-PTP via modification interacting with C site.

Science.gov (United States)

Du, Yongli; Zhang, Yanhui; Ling, Hao; Li, Qunyi; Shen, Jingkang

2018-01-20

PTP1B serving as a key negative regulator of insulin signaling is a novel target for type 2 diabetes and obesity. Modification at ring B of N-{4-[(3-Phenyl-ureido)-methyl]-phenyl}-methane-sulfonamide template to interact with residues Arg47 and Lys41 in the C site of PTP1B by molecular docking aided design resulted in the discovery of a series of novel high potent and selective inhibitors of PTP1B. The structure activity relationship interacting with the C site of PTP1B was well illustrated. Compounds 8 and 18 were shown to be the high potent and most promising PTP1B inhibitors with cellular activity and great selectivity over the highly homologous TCPTP and other PTPs. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

The pan phosphoinositide 3-kinase/mammalian target of rapamycin inhibitor SAR245409 (voxtalisib/XL765) blocks survival, adhesion and proliferation of primary chronic lymphocytic leukemia cells.

Science.gov (United States)

Thijssen, R; Ter Burg, J; van Bochove, G G W; de Rooij, M F M; Kuil, A; Jansen, M H; Kuijpers, T W; Baars, J W; Virone-Oddos, A; Spaargaren, M; Egile, C; van Oers, M H J; Eldering, E; Kersten, M J; Kater, A P

2016-02-01

The phosphoinositide 3-kinases (PI3Ks) are critical components of the B-cell receptor (BCR) pathway and have an important role in the pathobiology of chronic lymphocytic leukemia (CLL). Inhibitors of PI3Kδ block BCR-mediated cross-talk between CLL cells and the lymph node microenvironment and provide significant clinical benefit to CLL patients. However, the PI3Kδ inhibitors applied thus far have limited direct impact on leukemia cell survival and thus are unlikely to eradicate the disease. The use of inhibitors of multiple isoforms of PI3K might lead to deeper remissions. Here we demonstrate that the pan-PI3K/mammalian target of rapamycin inhibitor SAR245409 (voxtalisib/XL765) was more pro-apoptotic to CLL cells--irrespective of their ATM/p53 status--than PI3Kα or PI3Kδ isoform selective inhibitors. Furthermore, SAR245409 blocked CLL survival, adhesion and proliferation. Moreover, SAR245409 was a more potent inhibitor of T-cell-mediated production of cytokines, which support CLL survival. Taken together, our in vitro data provide a rationale for the evaluation of a pan-PI3K inhibitor in CLL patients.

Structural characterization of nonactive site, TrkA-selective kinase inhibitors

Energy Technology Data Exchange (ETDEWEB)

Su, Hua-Poo; Rickert, Keith; Burlein, Christine; Narayan, Kartik; Bukhtiyarova, Marina; Hurzy, Danielle M.; Stump, Craig A.; Zhang, Xufang; Reid, John; Krasowska-Zoladek, Alicja; Tummala, Srivanya; Shipman, Jennifer M.; Kornienko, Maria; Lemaire, Peter A.; Krosky, Daniel; Heller, Amanda; Achab, Abdelghani; Chamberlin, Chad; Saradjian, Peter; Sauvagnat, Berengere; Yang, Xianshu; Ziebell, Michael R.; Nickbarg, Elliott; Sanders, John M.; Bilodeau, Mark T.; Carroll, Steven S.; Lumb, Kevin J.; Soisson, Stephen M.; Henze, Darrell A.; Cooke, Andrew J. (Merck)

2016-12-30

Current therapies for chronic pain can have insufficient efficacy and lead to side effects, necessitating research of novel targets against pain. Although originally identified as an oncogene, Tropomyosin-related kinase A (TrkA) is linked to pain and elevated levels of NGF (the ligand for TrkA) are associated with chronic pain. Antibodies that block TrkA interaction with its ligand, NGF, are in clinical trials for pain relief. Here, we describe the identification of TrkA-specific inhibitors and the structural basis for their selectivity over other Trk family kinases. The X-ray structures reveal a binding site outside the kinase active site that uses residues from the kinase domain and the juxtamembrane region. Three modes of binding with the juxtamembrane region are characterized through a series of ligand-bound complexes. The structures indicate a critical pharmacophore on the compounds that leads to the distinct binding modes. The mode of interaction can allow TrkA selectivity over TrkB and TrkC or promiscuous, pan-Trk inhibition. This finding highlights the difficulty in characterizing the structure-activity relationship of a chemical series in the absence of structural information because of substantial differences in the interacting residues. These structures illustrate the flexibility of binding to sequences outside of—but adjacent to—the kinase domain of TrkA. This knowledge allows development of compounds with specificity for TrkA or the family of Trk proteins.

Metallochaperone UreG serves as a new target for design of urease inhibitor: A novel strategy for development of antimicrobials.

Directory of Open Access Journals (Sweden)

Xinming Yang

2018-01-01

Full Text Available Urease as a potential target of antimicrobial drugs has received considerable attention given its versatile roles in microbial infection. Development of effective urease inhibitors, however, is a significant challenge due to the deeply buried active site and highly specific substrate of a bacterial urease. Conventionally, urease inhibitors are designed by either targeting the active site or mimicking substrate of urease, which is not efficient. Up to now, only one effective inhibitor-acetohydroxamic acid (AHA-is clinically available, but it has adverse side effects. Herein, we demonstrate that a clinically used drug, colloidal bismuth subcitrate, utilizes an unusual way to inhibit urease activity, i.e., disruption of urease maturation process via functional perturbation of a metallochaperone, UreG. Similar phenomena were also observed in various pathogenic bacteria, suggesting that UreG may serve as a general target for design of new types of urease inhibitors. Using Helicobacter pylori UreG as a showcase, by virtual screening combined with experimental validation, we show that two compounds targeting UreG also efficiently inhibited urease activity with inhibitory concentration (IC50 values of micromolar level, resulting in attenuated virulence of the pathogen. We further demonstrate the efficacy of the compounds in a mammalian cell infection model. This study opens up a new opportunity for the design of more effective urease inhibitors and clearly indicates that metallochaperones involved in the maturation of important microbial metalloenzymes serve as new targets for devising a new type of antimicrobial drugs.

Metallochaperone UreG serves as a new target for design of urease inhibitor: A novel strategy for development of antimicrobials.

Science.gov (United States)

Yang, Xinming; Koohi-Moghadam, Mohamad; Wang, Runming; Chang, Yuen-Yan; Woo, Patrick C Y; Wang, Junwen; Li, Hongyan; Sun, Hongzhe

2018-01-01

Urease as a potential target of antimicrobial drugs has received considerable attention given its versatile roles in microbial infection. Development of effective urease inhibitors, however, is a significant challenge due to the deeply buried active site and highly specific substrate of a bacterial urease. Conventionally, urease inhibitors are designed by either targeting the active site or mimicking substrate of urease, which is not efficient. Up to now, only one effective inhibitor-acetohydroxamic acid (AHA)-is clinically available, but it has adverse side effects. Herein, we demonstrate that a clinically used drug, colloidal bismuth subcitrate, utilizes an unusual way to inhibit urease activity, i.e., disruption of urease maturation process via functional perturbation of a metallochaperone, UreG. Similar phenomena were also observed in various pathogenic bacteria, suggesting that UreG may serve as a general target for design of new types of urease inhibitors. Using Helicobacter pylori UreG as a showcase, by virtual screening combined with experimental validation, we show that two compounds targeting UreG also efficiently inhibited urease activity with inhibitory concentration (IC)50 values of micromolar level, resulting in attenuated virulence of the pathogen. We further demonstrate the efficacy of the compounds in a mammalian cell infection model. This study opens up a new opportunity for the design of more effective urease inhibitors and clearly indicates that metallochaperones involved in the maturation of important microbial metalloenzymes serve as new targets for devising a new type of antimicrobial drugs.

An AOP analysis of selective serotonin reuptake inhibitors (SSRIs) for fish.

Science.gov (United States)

McDonald, M Danielle

2017-07-01

Pharmaceuticals and personal care products (PPCPs) are found in measureable quantities within the aquatic environment. Selective serotonin reuptake inhibitor (SSRI) antidepressants are one class of pharmaceutical compound that has received a lot of attention. Consistent with most PPCPs, the pharmacokinetics and physiological impacts of SSRI treatment have been well-studied in small mammals and humans and this, combined with the evolutionary conservation of the serotonergic system across vertebrates, allows for the read-across of known SSRI effects in mammals to potential SSRI impacts on aquatic organisms. Using an Adverse Outcome Pathway (AOP) framework, this review examines the similarities and differences between the mammalian and teleost fish SSRI target, the serotonin transporter (SERT; SLC6A4), and the downstream impacts of elevated extracellular serotonin (5-HT; 5-hydroxytryptamine), the consequence of SERT inhibition, on organ systems and physiological processes within teleost fish. This review also intends to reveal potentially understudied endpoints for SSRI toxicity based on what is known to be controlled by 5-HT in fish. Copyright © 2017 Elsevier Inc. All rights reserved.

Design and synthesis of novel chalcones as potent selective monoamine oxidase-B inhibitors.

Science.gov (United States)

Hammuda, Arwa; Shalaby, Raed; Rovida, Stefano; Edmondson, Dale E; Binda, Claudia; Khalil, Ashraf

2016-05-23

A novel series of substituted chalcones were designed and synthesized to be evaluated as selective human MAO-B inhibitors. A combination of either methylsulfonyl or trifluoromethyl substituents on the aromatic ketone moiety with a benzodioxol ring on the other end of the chalcone scaffold was investigated. The compounds were tested for their inhibitory activities on both human MAO-A and B. All compounds appeared to be selective MAO-B inhibitors with Ki values in the micromolar to submicromolar range. Molecular modeling studies have been performed to get insight into the binding mode of the synthesized compounds to human MAO-B active site. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Target and Tissue Selectivity Prediction by Integrated Mechanistic Pharmacokinetic-Target Binding and Quantitative Structure Activity Modeling.

Science.gov (United States)

Vlot, Anna H C; de Witte, Wilhelmus E A; Danhof, Meindert; van der Graaf, Piet H; van Westen, Gerard J P; de Lange, Elizabeth C M

2017-12-04

Selectivity is an important attribute of effective and safe drugs, and prediction of in vivo target and tissue selectivity would likely improve drug development success rates. However, a lack of understanding of the underlying (pharmacological) mechanisms and availability of directly applicable predictive methods complicates the prediction of selectivity. We explore the value of combining physiologically based pharmacokinetic (PBPK) modeling with quantitative structure-activity relationship (QSAR) modeling to predict the influence of the target dissociation constant (K D ) and the target dissociation rate constant on target and tissue selectivity. The K D values of CB1 ligands in the ChEMBL database are predicted by QSAR random forest (RF) modeling for the CB1 receptor and known off-targets (TRPV1, mGlu5, 5-HT1a). Of these CB1 ligands, rimonabant, CP-55940, and Δ 8 -tetrahydrocanabinol, one of the active ingredients of cannabis, were selected for simulations of target occupancy for CB1, TRPV1, mGlu5, and 5-HT1a in three brain regions, to illustrate the principles of the combined PBPK-QSAR modeling. Our combined PBPK and target binding modeling demonstrated that the optimal values of the K D and k off for target and tissue selectivity were dependent on target concentration and tissue distribution kinetics. Interestingly, if the target concentration is high and the perfusion of the target site is low, the optimal K D value is often not the lowest K D value, suggesting that optimization towards high drug-target affinity can decrease the benefit-risk ratio. The presented integrative structure-pharmacokinetic-pharmacodynamic modeling provides an improved understanding of tissue and target selectivity.

Overcoming chemotherapy drug resistance by targeting inhibitors of apoptosis proteins (IAPs).

Science.gov (United States)

Rathore, Rama; McCallum, Jennifer E; Varghese, Elizabeth; Florea, Ana-Maria; Büsselberg, Dietrich

2017-07-01

Inhibitors of apoptosis (IAPs) are a family of proteins that play a significant role in the control of programmed cell death (PCD). PCD is essential to maintain healthy cell turnover within tissue but also to fight disease or infection. Uninhibited, IAPs can suppress apoptosis and promote cell cycle progression. Therefore, it is unsurprising that cancer cells demonstrate significantly elevated expression levels of IAPs, resulting in improved cell survival, enhanced tumor growth and subsequent metastasis. Therapies to target IAPs in cancer has garnered substantial scientific interest and as resistance to anti-cancer agents becomes more prevalent, targeting IAPs has become an increasingly attractive strategy to re-sensitize cancer cells to chemotherapies, antibody based-therapies and TRAIL therapy. Antagonism strategies to modulate the actions of XIAP, cIAP1/2 and survivin are the central focus of current research and this review highlights advances within this field with particular emphasis upon the development and specificity of second mitochondria-derived activator of caspase (SMAC) mimetics (synthetic analogs of endogenously expressed inhibitors of IAPs SMAC/DIABLO). While we highlight the potential of SMAC mimetics as effective single agent or combinatory therapies to treat cancer we also discuss the likely clinical implications of resistance to SMAC mimetic therapy, occasionally observed in cancer cell lines.

Synthesis, evaluation, and mechanism of N,N,N-trimethyl-D-glucosamine-(1→4)-chitooligosaccharides as selective inhibitors of glycosyl hydrolase family 20 β-N-acetyl-D-hexosaminidases.

Science.gov (United States)

Yang, You; Liu, Tian; Yang, Yongliang; Wu, Qingyue; Yang, Qing; Yu, Biao

2011-02-11

GH20 β-N-acetyl-D-hexosaminidases are enzymes involved in many vital processes. Inhibitors that specifically target GH20 enzymes in pests are of agricultural and economic importance. Structural comparison has revealed that the bacterial chitindegrading β-N-acetyl-D-hexosaminidases each have an extra +1 subsite in the active site; this structural difference could be exploited for the development of selective inhibitors. N,N,Ntrimethyl-D-glucosamine (TMG)-chitotriomycin, which contains three GlcNAc residues, is a natural selective inhibitor against bacterial and insect β-N-acetyl-D-hexosaminidases. However, our structural alignment analysis indicated that the two GlcNAc residues at the reducing end might be unnecessary. To prove this hypothesis, we designed and synthesized a series of TMG-chitotriomycin analogues containing one to four GlcNAc units. Inhibitory kinetics and molecular docking showed that TMG-(GlcNAc)(2), is as active as TMG-chitotriomycin [TMG-(GlcNAc)(3)]. The selective inhibition mechanism of TMG-chitotriomycin was also explained. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Clinical trials for BET inhibitors run ahead of the science.

Science.gov (United States)

Andrieu, Guillaume; Belkina, Anna C; Denis, Gerald V

2016-03-01

Several cancer clinical trials for small molecule inhibitors of BET bromodomain proteins have been initiated. There is enthusiasm for the anti-proliferative effect of inhibiting BRD4, one of the targets of these inhibitors, which is thought to cooperate with MYC, a long-desired target for cancer therapeutics. However, no current inhibitor is selective for BRD4 among the three somatic BET proteins, which include BRD2 and BRD3; their respective functions are partially overlapping and none are functionally redundant with BRD4. Each BET protein controls distinct transcriptional pathways that are important for functions beyond cancer cell proliferation, including insulin production, cytokine gene transcription, T cell differentiation, adipogenesis and most seriously, active repression of dangerous latent viruses like HIV. BET inhibitors have been shown to reactivate HIV in human cells. Failure to appreciate that at concentrations used, no available BET inhibitor is member-selective, or to develop a sound biological basis to understand the diverse functions of BET proteins before undertaking for these clinical trials is reckless and likely to lead to adverse events. More mechanistic information from new basic science studies should enable proper focus on the most relevant cancers and define the expected side effect profiles. Copyright © 2016 Elsevier Ltd. All rights reserved.

The growing pipeline of natural aminoacyl-tRNA synthetase inhibitors for malaria treatment.

Science.gov (United States)

Saint-Léger, Adélaïde; Sinadinos, Christopher; Ribas de Pouplana, Lluís

2016-04-02

Malaria remains a major global health problem. Parasite resistance to existing drugs makes development of new antimalarials an urgency. The protein synthesis machinery is an excellent target for the development of new anti-infectives, and aminoacyl-tRNA synthetases (aaRS) have been validated as antimalarial drug targets. However, avoiding the emergence of drug resistance and improving selectivity to target aaRS in apicomplexan parasites, such as Plasmodium falciparum, remain crucial challenges. Here we discuss such issues using examples of known inhibitors of P. falciparum aaRS, namely halofuginone, cladosporin and borrelidin (inhibitors of ProRS, LysRS and ThrRS, respectively). Encouraging recent results provide useful guidelines to facilitate the development of novel drug candidates which are more potent and selective against these essential enzymes.

CYP450 genotype and aggressive behavior on selective serotonin reuptake inhibitors

NARCIS (Netherlands)

Ekhart, Corine; Matic, Maja; Kant, Agnes; Schaik, Ron van; van Puijenbroek, Eugène

2017-01-01

AIM: Genetic variants for selective serotonin reuptake inhibitor (SSRI) metabolizing enzymes have been hypothesized to be a risk factor for aggression as adverse drug effect of SSRIs. Our aim was to assess the possible involvement of these polymorphisms on aggression when using SSRIs. MATERIALS &

Chemoproteomics-Aided Medicinal Chemistry for the Discovery of EPHA2 Inhibitors.

Science.gov (United States)

Heinzlmeir, Stephanie; Lohse, Jonas; Treiber, Tobias; Kudlinzki, Denis; Linhard, Verena; Gande, Santosh Lakshmi; Sreeramulu, Sridhar; Saxena, Krishna; Liu, Xiaofeng; Wilhelm, Mathias; Schwalbe, Harald; Kuster, Bernhard; Médard, Guillaume

2017-06-21

The receptor tyrosine kinase EPHA2 has gained attention as a therapeutic drug target for cancer and infectious diseases. However, EPHA2 research and EPHA2-based therapies have been hampered by the lack of selective small-molecule inhibitors. Herein we report the synthesis and evaluation of dedicated EPHA2 inhibitors based on the clinical BCR-ABL/SRC inhibitor dasatinib as a lead structure. We designed hybrid structures of dasatinib and the previously known EPHA2 binders CHEMBL249097, PD-173955, and a known EPHB4 inhibitor in order to exploit both the ATP pocket entrance as well as the ribose pocket as binding epitopes in the kinase EPHA2. Medicinal chemistry and inhibitor design were guided by a chemical proteomics approach, allowing early selectivity profiling of the newly synthesized inhibitor candidates. Concomitant protein crystallography of 17 inhibitor co-crystals delivered detailed insight into the atomic interactions that underlie the structure-affinity relationship. Finally, the anti-proliferative effect of the inhibitor candidates was confirmed in the glioblastoma cell line SF-268. In this work, we thus discovered a novel EPHA2 inhibitor candidate that features an improved selectivity profile while maintaining potency against EPHA2 and anticancer activity in SF-268 cells. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hypoxia-Inducible Factor-1 as a Therapeutic Target in Endometrial Cancer Management

Directory of Open Access Journals (Sweden)

Laura M. S. Seeber

2010-01-01

Full Text Available In the Western world, endometrial cancer (EC is the most common malignant tumor of the female genital tract. Solid tumors like EC outgrow their vasculature resulting in hypoxia. Tumor hypoxia is important because it renders an aggressive phenotype and leads to radio- and chemo-therapy resistance. Hypoxia-inducible factor-1 (HIF-1 plays an essential role in the adaptive cellular response to hypoxia and is associated with poor clinical outcome in EC. Therefore, HIF-1 could be an attractive therapeutic target. Selective HIF-1 inhibitors have not been identified. A number of nonselective inhibitors which target signaling pathways upstream or downstream HIF-1 are known to decrease HIF-1 protein levels. In clinical trials for the treatment of advanced and/or recurrent EC are the topoisomerase I inhibitor Topotecan, mTOR-inhibitor Rapamycin, and angiogenesis inhibitor Bevacizumab. Preliminary data shows encouraging results for these agents. Further work is needed to identify selective HIF-1 inhibitors and to translate these into clinical trials.

Effect of selective phosphodiesterase inhibitors on the rat eosinophil chemotactic response in vitro

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Alves Alessandra C

1997-01-01

Full Text Available In the present study, we have performed a comparative analysis of the effect of selective inhibitors of phosphodiesterase (PDE type III, IV and V on eosinophil chemotaxis triggered by platelet activating factor (PAF and leukotriene B4 (LTB4 in vitro. The effect of the analogues N6-2'-O-dibutyryladenosine 3':5' cyclic monophosphate (Bt2 cyclic AMP and N2-2'-O- dibutyrylguanosine 3':5' cyclic monophosphate (Bt2 cyclic GMP has also been determined. The eosinophils were obtained from the peritoneal cavity of naive Wistar rats and purified in discontinuous Percoll gradients to 85-95% purity. We observed that pre-incubation of eosinophils with the PDE type IV inhibitor rolipram suppressed the chemotactic response triggered by PAF and LTB4, in association with an increase in the intracellular levels of cyclic AMP. In contrast, neither zaprinast (type V inhibitor nor type III inhibitors milrinone and SK&F 94836 affected the eosinophil migration. Only at the highest concentration tested did the analogue Bt2 cyclic AMP suppress the eosinophil chemotaxis, under conditions where Bt2 cyclic GMP was ineffective. We have concluded that inhibition of PDE IV, but not PDE III or V, was able to block the eosinophil chemotaxis in vitro, suggesting that the suppressive activity of selective PDE IV inhibitors on tissue eosinophil accumulation may, at least, be partially dependent on their ability to directly inhibit the eosinophil migration.

Selective Serotonin Reuptake Inhibitor-Induced Sexual Dysfunction in Adolescents: A Review.

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Scharko, Alexander M.

2004-01-01

Objective: To review the existing literature on selective serotonin reuptake inhibitor (SSRI)-induced sexual dysfunction in adolescents. Method: A literature review of SSRI-induced adverse effects in adolescents focusing on sexual dysfunction was done. Nonsexual SSRI-induced adverse effects were compared in adult and pediatric populations.…

CS2164, a novel multi-target inhibitor against tumor angiogenesis, mitosis and chronic inflammation with anti-tumor potency.

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Zhou, You; Shan, Song; Li, Zhi-Bin; Xin, Li-Jun; Pan, De-Si; Yang, Qian-Jiao; Liu, Ying-Ping; Yue, Xu-Peng; Liu, Xiao-Rong; Gao, Ji-Zhou; Zhang, Jin-Wen; Ning, Zhi-Qiang; Lu, Xian-Ping

2017-03-01

Although inhibitors targeting tumor angiogenic pathway have provided improvement for clinical treatment in patients with various solid tumors, the still very limited anti-cancer efficacy and acquired drug resistance demand new agents that may offer better clinical benefits. In the effort to find a small molecule potentially targeting several key pathways for tumor development, we designed, discovered and evaluated a novel multi-kinase inhibitor, CS2164. CS2164 inhibited the angiogenesis-related kinases (VEGFR2, VEGFR1, VEGFR3, PDGFRα and c-Kit), mitosis-related kinase Aurora B and chronic inflammation-related kinase CSF-1R in a high potency manner with the IC 50 at a single-digit nanomolar range. Consequently, CS2164 displayed anti-angiogenic activities through suppression of VEGFR/PDGFR phosphorylation, inhibition of ligand-dependent cell proliferation and capillary tube formation, and prevention of vasculature formation in tumor tissues. CS2164 also showed induction of G2/M cell cycle arrest and suppression of cell proliferation in tumor tissues through the inhibition of Aurora B-mediated H3 phosphorylation. Furthermore, CS2164 demonstrated the inhibitory effect on CSF-1R phosphorylation that led to the suppression of ligand-stimulated monocyte-to-macrophage differentiation and reduced CSF-1R + cells in tumor tissues. The in vivo animal efficacy studies revealed that CS2164 induced remarkable regression or complete inhibition of tumor growth at well-tolerated oral doses in several human tumor xenograft models. Collectively, these results indicate that CS2164 is a highly selective multi-kinase inhibitor with potent anti-tumor activities against tumor angiogenesis, mitosis and chronic inflammation, which may provide the rationale for further clinical assessment of CS2164 as a therapeutic agent in the treatment of cancer. © 2016 The Authors. Cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese Cancer Association.

In-silico Leishmania Target Selectivity of Antiparasitic Terpenoids

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Ifedayo Victor Ogungbe

2013-07-01

Full Text Available Neglected Tropical Diseases (NTDs, like leishmaniasis, are major causes of mortality in resource-limited countries. The mortality associated with these diseases is largely due to fragile healthcare systems, lack of access to medicines, and resistance by the parasites to the few available drugs. Many antiparasitic plant-derived isoprenoids have been reported, and many of them have good in vitro activity against various forms of Leishmania spp. In this work, potential Leishmania biochemical targets of antiparasitic isoprenoids were studied in silico. Antiparasitic monoterpenoids selectively docked to L. infantum nicotinamidase, L. major uridine diphosphate-glucose pyrophosphorylase and methionyl t-RNA synthetase. The two protein targets selectively targeted by germacranolide sesquiterpenoids were L. major methionyl t-RNA synthetase and dihydroorotate dehydrogenase. Diterpenoids generally favored docking to L. mexicana glycerol-3-phosphate dehydrogenase. Limonoids also showed some selectivity for L. mexicana glycerol-3-phosphate dehydrogenase and L. major dihydroorotate dehydrogenase while withanolides docked more selectively with L. major uridine diphosphate-glucose pyrophosphorylase. The selectivity of the different classes of antiparasitic compounds for the protein targets considered in this work can be explored in fragment- and/or structure-based drug design towards the development of leads for new antileishmanial drugs.

When Teaching Gets Tough--Professional Community Inhibitors of Teacher-Targeted Bullying and Turnover Intentions

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Pyhältö, Kirsi; Pietarinen, Janne; Soini, Tiina

2015-01-01

Bullying in school has become an international concern in recent decades. Yet, we know surprisingly little about inhibitors of teacher-targeted bullying. The study focused on exploring the interrelation between the teacher-working environment fit, bullying, experienced exhaustion and turnover intentions. Altogether 2310 comprehensive school…

Screening and identification of potential PTP1B allosteric inhibitors using in silico and in vitro approaches.

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Shinde, Ranajit Nivrutti; Kumar, G Siva; Eqbal, Shahbaz; Sobhia, M Elizabeth

2018-01-01

Protein tyrosine phosphatase 1B (PTP1B) is a validated therapeutic target for Type 2 diabetes due to its specific role as a negative regulator of insulin signaling pathways. Discovery of active site directed PTP1B inhibitors is very challenging due to highly conserved nature of the active site and multiple charge requirements of the ligands, which makes them non-selective and non-permeable. Identification of the PTP1B allosteric site has opened up new avenues for discovering potent and selective ligands for therapeutic intervention. Interactions made by potent allosteric inhibitor in the presence of PTP1B were studied using Molecular Dynamics (MD). Computationally optimized models were used to build separate pharmacophore models of PTP1B and TCPTP, respectively. Based on the nature of interactions the target residues offered, a receptor based pharmacophore was developed. The pharmacophore considering conformational flexibility of the residues was used for the development of pharmacophore hypothesis to identify potentially active inhibitors by screening large compound databases. Two pharmacophore were successively used in the virtual screening protocol to identify potential selective and permeable inhibitors of PTP1B. Allosteric inhibition mechanism of these molecules was established using molecular docking and MD methods. The geometrical criteria values confirmed their ability to stabilize PTP1B in an open conformation. 23 molecules that were identified as potential inhibitors were screened for PTP1B inhibitory activity. After screening, 10 molecules which have good permeability values were identified as potential inhibitors of PTP1B. This study confirms that selective and permeable inhibitors can be identified by targeting allosteric site of PTP1B.

Targeting Mycobacterium tuberculosis nucleoid-associated protein HU with structure-based inhibitors

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Bhowmick, Tuhin; Ghosh, Soumitra; Dixit, Karuna; Ganesan, Varsha; Ramagopal, Udupi A.; Dey, Debayan; Sarma, Siddhartha P.; Ramakumar, Suryanarayanarao; Nagaraja, Valakunja

2014-06-01

The nucleoid-associated protein HU plays an important role in maintenance of chromosomal architecture and in global regulation of DNA transactions in bacteria. Although HU is essential for growth in Mycobacterium tuberculosis (Mtb), there have been no reported attempts to perturb HU function with small molecules. Here we report the crystal structure of the N-terminal domain of HU from Mtb. We identify a core region within the HU-DNA interface that can be targeted using stilbene derivatives. These small molecules specifically inhibit HU-DNA binding, disrupt nucleoid architecture and reduce Mtb growth. The stilbene inhibitors induce gene expression changes in Mtb that resemble those induced by HU deficiency. Our results indicate that HU is a potential target for the development of therapies against tuberculosis.

Small-Molecule Inhibitors of the Type III Secretion System

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Lingling Gu

2015-09-01

Full Text Available Drug-resistant pathogens have presented increasing challenges to the discovery and development of new antibacterial agents. The type III secretion system (T3SS, existing in bacterial chromosomes or plasmids, is one of the most complicated protein secretion systems. T3SSs of animal and plant pathogens possess many highly conserved main structural components comprised of about 20 proteins. Many Gram-negative bacteria carry T3SS as a major virulence determinant, and using the T3SS, the bacteria secrete and inject effector proteins into target host cells, triggering disease symptoms. Therefore, T3SS has emerged as an attractive target for antimicrobial therapeutics. In recent years, many T3SS-targeting small-molecule inhibitors have been discovered; these inhibitors prevent the bacteria from injecting effector proteins and from causing pathophysiology in host cells. Targeting the virulence of Gram-negative pathogens, rather than their survival, is an innovative and promising approach that may greatly reduce selection pressures on pathogens to develop drug-resistant mutations. This article summarizes recent progress in the search for promising small-molecule T3SS inhibitors that target the secretion and translocation of bacterial effector proteins.

Targeting neuroblastoma stem cells with retinoic acid and proteasome inhibitor.

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Barbara Hämmerle

Full Text Available Neuroblastma cell lines contain a side-population of cells which express stemness markers. These stem-like cells may represent the potential underlying mechanism for resistance to conventional therapy and recurrence of neuroblastoma in patients.To develop novel strategies for targeting the side-population of neurobastomas, we analyzed the effects of 13-cis-retinoic acid (RA combined with the proteasome inhibitor MG132. The short-term action of the treatment was compared with effects after a 5-day recovery period during which both chemicals were withdrawn. RA induced growth arrest and differentiation of SH-SY5Y and SK-N-BE(2 neuroblastoma cell lines. Inhibition of the proteasome caused apoptosis in both cell lines, thus, revealing the critical role of this pathway in the regulated degradation of proteins involved in neuroblastoma proliferation and survival. The combination of RA with MG132 induced apoptosis in a dose-dependent manner, in addition to promoting G2/M arrest in treated cultures. Interestingly, expression of stem cell markers such as Nestin, Sox2, and Oct4 were reduced after the recovery period of combined treatment as compared with untreated cells or treated cells with either compound alone. Consistent with this, neurosphere formation was significantly impaired by the combined treatment of RA and MG132.Given that stem-like cells are associated with resistant to conventional therapy and are thought to be responsible for relapse, our results suggest that dual therapy of RA and proteasome inhibitor might be beneficial for targeting the side-population of cells associated residual disease in high-risk neuroblastoma.

Are Selective Serotonin Reuptake Inhibitors Safe for Drivers? What is the Evidence?

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Ravera, Silvia; Ramaekers, Johannes G.; de Jong-van den Berg, Lolkje T. W.; de Gier, Johan J.; de Jong-van den Berg, [No Value

Background: Selective serotonin reuptake inhibitors (SSRIs) are widely used medications to treat several psychiatric diseases and, above all, depression. They seem to be as effective as older antidepressants but have a different adverse effect profile. Despite their favorable safety profile, little

Selective serotonin reuptake inhibitor (SSRI antidepressants, prolactin and breast cancer

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Janet eAshbury

2012-12-01

Full Text Available Selective serotonin reuptake inhibitors (SSRIs are a widely prescribed class of anti-depressants. Laboratory and epidemiologic evidence suggests that a prolactin-mediated mechanism secondary to increased serotonin levels at neuronal synapses could lead to a potentially carcinogenic effect of SSRIs. In this population-based case-control study, we evaluated the association between SSRI use and breast cancer risk as a function of their relative degree of inhibition of serotonin reuptake as a proxy for their impact on prolactin levels. Cases were 2,129 women with primary invasive breast cancer diagnosed from 2003-2007, and controls were 21,297 women randomly selected from the population registry. Detailed information for each SSRI prescription dispensed was compiled using the Saskatchewan prescription database. Logistic regression was used to evaluate the impact of use of high and lower inhibitors of serotonin reuptake and duration of use, as well as to assess the effect of individual high inhibitors on the risk of breast cancer. Exclusive users of high or lower inhibitors of serotonin reuptake were not at increased risk for breast cancer compared with nonusers of SSRIs (OR = 1.01, CI = 0.88-1.17 and OR = 0.91, CI = 0.67-1.25 respectively, regardless of their duration of use or menopausal status. While we cannot rule out the possibility of a clinically important risk increase (OR = 1.83, CI = 0.99-3.40 for long-term users of sertraline (≥24 prescriptions, given the small number of exposed cases (n=12, the borderline statistical significance and the wide confidence interval, these results need to be interpreted cautiously. In this large population-based case-control study, we found no conclusive evidence of breast cancer risk associated with the use of SSRIs even after assessing the degree of serotonin reuptake inhibition and duration of use. Our results do not support the serotonin-mediated pathway for the prolactin-breast cancer hypothesis.

Mechanisms of Acquired Drug Resistance to the HDAC6 Selective Inhibitor Ricolinostat Reveals Rational Drug-Drug Combination with Ibrutinib.

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Amengual, Jennifer E; Prabhu, Sathyen A; Lombardo, Maximilian; Zullo, Kelly; Johannet, Paul M; Gonzalez, Yulissa; Scotto, Luigi; Serrano, Xavier Jirau; Wei, Ying; Duong, Jimmy; Nandakumar, Renu; Cremers, Serge; Verma, Akanksha; Elemento, Olivier; O'Connor, Owen A

2017-06-15

Purpose: Pan-class I/II histone deacetylase (HDAC) inhibitors are effective treatments for select lymphomas. Isoform-selective HDAC inhibitors are emerging as potentially more targeted agents. ACY-1215 (ricolinostat) is a first-in-class selective HDAC6 inhibitor. To better understand the discrete function of HDAC6 and its role in lymphoma, we developed a lymphoma cell line resistant to ACY-1215. Experimental Design: The diffuse large B-cell lymphoma cell line OCI-Ly10 was exposed to increasing concentrations of ACY-1215 over an extended period of time, leading to the development of a resistant cell line. Gene expression profiling (GEP) was performed to investigate differentially expressed genes. Combination studies of ACY-1215 and ibrutinib were performed in cell lines, primary human lymphoma tissue, and a xenograft mouse model. Results: Systematic incremental increases in drug exposure led to the development of distinct resistant cell lines with IC 50 values 10- to 20-fold greater than that for parental lines. GEP revealed upregulation of MAPK10, HELIOS, HDAC9, and FYN, as well as downregulation of SH3BP5 and LCK. Gene-set enrichment analysis (GSEA) revealed modulation of the BTK pathway. Ibrutinib was found to be synergistic with ACY-1215 in cell lines as well as in 3 primary patient samples of lymphoma. In vivo confirmation of antitumor synergy was demonstrated with a xenograft of DLBCL. Conclusions: The development of this ACY-1215-resistant cell line has provided valuable insights into the mechanistic role of HDAC6 in lymphoma and offered a novel method to identify rational synergistic drug combinations. Translation of these findings to the clinic is underway. Clin Cancer Res; 23(12); 3084-96. ©2016 AACR . ©2016 American Association for Cancer Research.

THE PRESENCE OF 5 CYCLIC-NUCLEOTIDE PHOSPHODIESTERASE ISOENZYME ACTIVITIES IN BOVINE TRACHEAL SMOOTH-MUSCLE AND THE FUNCTIONAL-EFFECTS OF SELECTIVE INHIBITORS

NARCIS (Netherlands)

VANAMSTERDAM, RGM; DEBOER, J; TENBERGE, RE; NICHOLSON, CD; ZAAGSMA, J

1991-01-01

1 The profile of cyclic nucleotide phosphodiesterase (PDE) isoenzymes and the relaxant effects of isoenzyme selective inhibitors were examined in bovine tracheal smooth muscle. The compounds examined were the non-selective inhibitor 3-isobutyl-1-methylxanthine (IBMX), zaprinast (PDE V selective),

Structure-Based Design of a Novel Series of Potent, Selective Inhibitors of the Class I Phosphatidylinositol 3-Kinases

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Smith, Adrian L.; D’Angelo, Noel D.; Bo, Yunxin Y.; Booker, Shon K.; Cee, Victor J.; Herberich, Brad; Hong, Fang-Tsao; Jackson, Claire L.M.; Lanman, Brian A.; Liu, Longbin; Nishimura, Nobuko; Pettus, Liping H.; Reed, Anthony B.; Tadesse, Seifu; Tamayo, Nuria A.; Wurz, Ryan P.; Yang, Kevin; Andrews, Kristin L.; Whittington, Douglas A.; McCarter, John D.; Miguel, Tisha San; Zalameda, Leeanne; Jiang, Jian; Subramanian, Raju; Mullady, Erin L.; Caenepeel, Sean; Freeman, Daniel J.; Wang, Ling; Zhang, Nancy; Wu, Tian; Hughes, Paul E.; Norman, Mark H. (Amgen)

2012-09-17

A highly selective series of inhibitors of the class I phosphatidylinositol 3-kinases (PI3Ks) has been designed and synthesized. Starting from the dual PI3K/mTOR inhibitor 5, a structure-based approach was used to improve potency and selectivity, resulting in the identification of 54 as a potent inhibitor of the class I PI3Ks with excellent selectivity over mTOR, related phosphatidylinositol kinases, and a broad panel of protein kinases. Compound 54 demonstrated a robust PD-PK relationship inhibiting the PI3K/Akt pathway in vivo in a mouse model, and it potently inhibited tumor growth in a U-87 MG xenograft model with an activated PI3K/Akt pathway.

Discovery and antiplatelet activity of a selective PI3Kβ inhibitor (MIPS-9922).

Science.gov (United States)

Zheng, Zhaohua; Pinson, Jo-Anne; Mountford, Simon J; Orive, Stephanie; Schoenwaelder, Simone M; Shackleford, David; Powell, Andrew; Nelson, Erin M; Hamilton, Justin R; Jackson, Shaun P; Jennings, Ian G; Thompson, Philip E

2016-10-21

A series of amino-substituted triazines were developed and examined for PI3Kβ inhibition and anti-platelet function. Structural adaptations of a morpholine ring of the prototype pan-PI3K inhibitor ZSTK474 yielded PI3Kβ selective compounds, where the selectivity largely derives from an interaction with the non-conserved Asp862 residue, as shown by site directed mutagenesis. The most PI3Kβ selective inhibitor from the series was studied in detail through a series of in vitro and in vivo functional studies. MIPS-9922, 10 potently inhibited ADP-induced washed platelet aggregation. It also inhibited integrin αIIbβ3 activation and αIIbβ3 dependent platelet adhesion to immobilized vWF under high shear. It prevented arterial thrombus formation in the in vivo electrolytic mouse model of thrombosis without inducing prolonged bleeding or excess blood loss. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Target selection for the HRIBF Project

International Nuclear Information System (INIS)

Dellwo, J.; Alton, G.D.; Batchelder, J.C.

1994-01-01

Experiments are in progress at the Oak Ridge National Laboratory (ORNL) which are designed to select the most appropriate target materials for generating particular radioactive ion beams for the Holifield Radioactive Ion Beam Facility (HRIBF). The 25-MV tandem accelerator is used to implant stable complements of interesting radioactive elements into refractory targets mounted in a high-temperature FEBIAD ion source which is on-line at the UNISOR facility. These experiments permit selection of the target material most appropriate for the rapid release of the element of interest, as well as realistic estimates of the efficiency of the FEBIAD source. From diffusion release data information on the release times and diffusion coefficients can be derived. Diffusion coefficients for CI implanted into and diffused from CeS and Zr 5 Si 3 and As, Br, and Se implanted into and diffused from Zr 5 Ge 3 have been derived from the resulting intensity versus time profiles

Target selection biases from recent experience transfer across effectors.

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Moher, Jeff; Song, Joo-Hyun

2016-02-01

Target selection is often biased by an observer's recent experiences. However, not much is known about whether these selection biases influence behavior across different effectors. For example, does looking at a red object make it easier to subsequently reach towards another red object? In the current study, we asked observers to find the uniquely colored target object on each trial. Randomly intermixed pre-trial cues indicated the mode of action: either an eye movement or a visually guided reach movement to the target. In Experiment 1, we found that priming of popout, reflected in faster responses following repetition of the target color on consecutive trials, occurred regardless of whether the effector was repeated from the previous trial or not. In Experiment 2, we examined whether an inhibitory selection bias away from a feature could transfer across effectors. While priming of popout reflects both enhancement of the repeated target features and suppression of the repeated distractor features, the distractor previewing effect isolates a purely inhibitory component of target selection in which a previewed color is presented in a homogenous display and subsequently inhibited. Much like priming of popout, intertrial suppression biases in the distractor previewing effect transferred across effectors. Together, these results suggest that biases for target selection driven by recent trial history transfer across effectors. This indicates that representations in memory that bias attention towards or away from specific features are largely independent from their associated actions.

Class 1-Selective Histone Deacetylase (HDAC) Inhibitors Enhance HIV Latency Reversal while Preserving the Activity of HDAC Isoforms Necessary for Maximal HIV Gene Expression.

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Zaikos, Thomas D; Painter, Mark M; Sebastian Kettinger, Nadia T; Terry, Valeri H; Collins, Kathleen L

2018-03-15

reservoir elimination. Because histone deacetylases (HDACs) promote HIV latency, HDAC inhibitors have been a focus of HIV cure research. However, many of these inhibitors broadly affect multiple classes of HDACs, including those that promote HIV gene expression (class 1 HDACs). Here, we demonstrate that targeted treatment with class 1-selective HDAC inhibitors induced more potent HIV latency reversal than broadly acting agents. Additionally, we provide evidence that broadly acting HDIs are limited by inhibitory effects on non-class 1 HDACs that support the activity of proviral factors. Thus, our work demonstrates that the use of targeted approaches to induce maximum latency reversal affords the greatest likelihood of reservoir elimination. Copyright © 2018 American Society for Microbiology.

Effect of selective versus non-selective cyclooxygenase inhibitors on ischemia-reperfusion-induced hepatic injury in rats.

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Abdel-Gaber, Seham A; Ibrahim, Mohamed A; Amin, Entesar F; Ibrahim, Salwa A; Mohammed, Rehab K; Abdelrahman, Aly M

2015-08-01

Ischemia-reperfusion (IR) injury represents an important pathological process of liver injury during major hepatic surgery. The role of cyclooxygenase (COX) enzymes in the pathogenesis of ischemia-reperfusion (IR)-induced liver injury is not clear. This study investigated the effect of a selective COX-2 inhibitor, celecoxib, versus non-selective, indomethacin, on hepatic IR injury in rats. Hepatic IR was induced in adult male rats. The animals were divided into 4 groups: normal control (sham group), IR non-treated group; IR-indomethacin-treated group; and IR-celecoxib-treated group. Liver injury was evaluated by serum alanine aminotransferase (ALT) and a histopathological examination of liver tissues. Hepatic tissue content of oxidative stress parameters glutathione peroxidase (GPx), superoxide dismutase (SOD), catalase, malondialdehyde (MDA), nitric oxide (NO) and the inflammatory marker, tumor necrosis factor-alpha, (TNF-α) were measured. Moreover, the immunohistochemical detection of endothelial NO synthase (eNOS), inducible NO synthase (iNOS), and caspase-3 in the hepatic tissue was performed. Celecoxib, but not indomethacin, significantly attenuated hepatic IR injury as evidenced by reduction in serum ALT as well as by improvement in the histopathological scoring. Such effect was associated with attenuation in oxidative stress and TNF-α, along with modulation of immunohistochemical expression of eNOS, iNOS and caspase-3 in the hepatic tissue. The present study concluded that selective COX-2 inhibition (but not non-selective), is hepatoprotective against liver IR injury; indicating a differential role of COX-1 versus COX-2. Modulation of iNOS, eNOS and caspase-3 might participate in the protective effect of selective COX-2-inhibitors. Copyright © 2015 Elsevier Inc. All rights reserved.

Selective serotonin reuptake inhibitor suppression of HIV infectivity and replication.

Science.gov (United States)

Benton, Tami; Lynch, Kevin; Dubé, Benoit; Gettes, David R; Tustin, Nancy B; Ping Lai, Jian; Metzger, David S; Blume, Joshua; Douglas, Steven D; Evans, Dwight L

2010-11-01

To test the hypothesis that the selective serotonin reuptake inhibitor (SSRI) citalopram would down-regulate human immunodeficiency virus (HIV) infectivity and that the greatest effects would be seen in people with depression. Depression is a risk factor for morbidity and mortality in HIV/acquired immune deficiency syndrome. Serotonin (5-HT) neurotransmission has been implicated in the pathobiology of depression, and pharmacologic therapies for depression target this system. The 5-HT transporter and 5-HT receptors are widely distributed throughout the central nervous and immune systems. Depression has been associated with suppression of natural killer cells and CD8(+) lymphocytes, key regulators of HIV infection. Ex vivo models for acute and chronic HIV infection were used to study the effects of citalopram on HIV viral infection and replication in 48 depressed and nondepressed women. For both the acute and chronic infection models, HIV reverse transcriptase activity was measured in the citalopram treatment condition and the control condition. The SSRI significantly down-regulated the reverse transcriptase response in both the acute and chronic infection models. Specifically, citalopram significantly decreased the acute HIV infectivity of macrophages. Citalopram also significantly decreased HIV viral replication in the latently infected T-cell line and in the latently infected macrophage cell line. There was no difference in down-regulation by depression status. These studies suggest that an SSRI enhances natural killer/CD8 noncytolytic HIV suppression in HIV/acquired immune deficiency syndrome and decreases HIV viral infectivity of macrophages, ex vivo, suggesting the need for in vivo studies to determine a potential role for agents targeting serotonin in the host defense against HIV.

Structural Insights into the Mechanisms of Action of Short-Peptide HIV-1 Fusion Inhibitors Targeting the Gp41 Pocket

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Xiujuan Zhang

2018-02-01

Full Text Available The deep hydrophobic pocket of HIV-1 gp41 has been considered a drug target, but short-peptides targeting this site usually lack potent antiviral activity. By applying the M-T hook structure, we previously generated highly potent short-peptide fusion inhibitors that specifically targeted the pocket site, such as MT-SC22EK, HP23L, and LP-11. Here, the crystal structures of HP23L and LP-11 bound to the target mimic peptide N36 demonstrated the critical intrahelical and interhelical interactions, especially verifying that the hook-like conformation was finely adopted while the methionine residue was replaced by the oxidation-less prone residue leucine, and that addition of an extra glutamic acid significantly enhanced the binding and inhibitory activities. The structure of HP23L bound to N36 with two mutations (E49K and L57R revealed the critical residues and motifs mediating drug resistance and provided new insights into the mechanism of action of inhibitors. Therefore, the present data help our understanding for the structure-activity relationship (SAR of HIV-1 fusion inhibitors and facilitate the development of novel antiviral drugs.

Structural and mechanistic basis of differentiated inhibitors of the acute pancreatitis target kynurenine-3-monooxygenase

Science.gov (United States)

Hutchinson, Jonathan P.; Rowland, Paul; Taylor, Mark R. D.; Christodoulou, Erica M.; Haslam, Carl; Hobbs, Clare I.; Holmes, Duncan S.; Homes, Paul; Liddle, John; Mole, Damian J.; Uings, Iain; Walker, Ann L.; Webster, Scott P.; Mowat, Christopher G.; Chung, Chun-Wa

2017-06-01

Kynurenine-3-monooxygenase (KMO) is a key FAD-dependent enzyme of tryptophan metabolism. In animal models, KMO inhibition has shown benefit in neurodegenerative diseases such as Huntington's and Alzheimer's. Most recently it has been identified as a target for acute pancreatitis multiple organ dysfunction syndrome (AP-MODS); a devastating inflammatory condition with a mortality rate in excess of 20%. Here we report and dissect the molecular mechanism of action of three classes of KMO inhibitors with differentiated binding modes and kinetics. Two novel inhibitor classes trap the catalytic flavin in a previously unobserved tilting conformation. This correlates with picomolar affinities, increased residence times and an absence of the peroxide production seen with previous substrate site inhibitors. These structural and mechanistic insights culminated in GSK065(C1) and GSK366(C2), molecules suitable for preclinical evaluation. Moreover, revising the repertoire of flavin dynamics in this enzyme class offers exciting new opportunities for inhibitor design.

The Guareschi Pyridine Scaffold as a Valuable Platform for the Identification of Selective PI3K Inhibitors

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Ubaldina Galli

2015-09-01

Full Text Available A novel series of 4-aryl-3-cyano-2-(3-hydroxyphenyl-6-morpholino-pyridines have been designed as potential phosphatidylinositol-3-kinase (PI3K inhibitors. The compounds have been synthesized using the Guareschi reaction to prepare the key 4-aryl-3-cyano-2,6-dihydroxypyridine intermediate. A different selectivity according to the nature of the aryl group has been observed. Compound 9b is a selective inhibitor against the PI3Kα isoform, maintaining a good inhibitory activity. Docking studies were also performed in order to rationalize its profile of selectivity.

The Guareschi Pyridine Scaffold as a Valuable Platform for the Identification of Selective PI3K Inhibitors.

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Galli, Ubaldina; Ciraolo, Elisa; Massarotti, Alberto; Margaria, Jean Piero; Sorba, Giovanni; Hirsch, Emilio; Tron, Gian Cesare

2015-09-18

A novel series of 4-aryl-3-cyano-2-(3-hydroxyphenyl)-6-morpholino-pyridines have been designed as potential phosphatidylinositol-3-kinase (PI3K) inhibitors. The compounds have been synthesized using the Guareschi reaction to prepare the key 4-aryl-3-cyano-2,6-dihydroxypyridine intermediate. A different selectivity according to the nature of the aryl group has been observed. Compound 9b is a selective inhibitor against the PI3Kα isoform, maintaining a good inhibitory activity. Docking studies were also performed in order to rationalize its profile of selectivity.

Promising Tools in Prostate Cancer Research: Selective Non-Steroidal Cytochrome P450 17A1 Inhibitors

Science.gov (United States)

Bonomo, Silvia; Hansen, Cecilie H.; Petrunak, Elyse M.; Scott, Emily E.; Styrishave, Bjarne; Jørgensen, Flemming Steen; Olsen, Lars

2016-07-01

Cytochrome P450 17A1 (CYP17A1) is an important target in the treatment of prostate cancer because it produces androgens required for tumour growth. The FDA has approved only one CYP17A1 inhibitor, abiraterone, which contains a steroidal scaffold similar to the endogenous CYP17A1 substrates. Abiraterone is structurally similar to the substrates of other cytochrome P450 enzymes involved in steroidogenesis, and interference can pose a liability in terms of side effects. Using non-steroidal scaffolds is expected to enable the design of compounds that interact more selectively with CYP17A1. Therefore, we combined a structure-based virtual screening approach with density functional theory (DFT) calculations to suggest non-steroidal compounds selective for CYP17A1. In vitro assays demonstrated that two such compounds selectively inhibited CYP17A1 17α-hydroxylase and 17,20-lyase activities with IC50 values in the nanomolar range, without affinity for the major drug-metabolizing CYP2D6 and CYP3A4 enzymes and CYP21A2, with the latter result confirmed in human H295R cells.

Receptor tyrosine kinase (c-Kit inhibitors: a potential therapeutic target in cancer cells

Directory of Open Access Journals (Sweden)

Abbaspour Babaei M

2016-08-01

-Kit for future cancer therapy. In addition, it has c-Kit inhibitor drug properties and their functions have been listed in tables and demonstrated in schematic pictures. This review also has collected previous studies that targeted c-Kit as a novel strategy for cancer therapy. This paper further emphasizes the advantages of this approach, as well as the limitations that must be addressed in the future. Finally, although c-Kit is an attractive target for cancer therapy, based on the outcomes of treatment of patients with c-Kit inhibitors, it is unlikely that Kit inhibitors alone can lead to cure. It seems that c-Kit mutations alone are not sufficient for tumorogenesis, but do play a crucial role in cancer occurrence. Keywords: c-Kit, cancer, oncogene, cancer therapy

RVX-297- a novel BD2 selective inhibitor of BET bromodomains

Energy Technology Data Exchange (ETDEWEB)

Kharenko, Olesya A., E-mail: olesya@zenithepigenetics.com [Zenith Epigenetics, Suite 300, 4820 Richard Road SW, Calgary, Alberta, T3E 6L1 (Canada); Gesner, Emily M.; Patel, Reena G.; Norek, Karen [Zenith Epigenetics, Suite 300, 4820 Richard Road SW, Calgary, Alberta, T3E 6L1 (Canada); White, Andre; Fontano, Eric; Suto, Robert K. [Xtal BioStructures, Inc., 12 Michigan Dr., Natick, MA 01760 (United States); Young, Peter R.; McLure, Kevin G.; Hansen, Henrik C. [Zenith Epigenetics, Suite 300, 4820 Richard Road SW, Calgary, Alberta, T3E 6L1 (Canada)

2016-08-12

Bromodomains are epigenetic readers that specifically bind to the acetyl lysine residues of histones and transcription factors. Small molecule BET bromodomain inhibitors can disrupt this interaction which leads to potential modulation of several disease states. Here we describe the binding properties of a novel BET inhibitor RVX-297 that is structurally related to the clinical compound RVX-208, currently undergoing phase III clinical trials for the treatment of cardiovascular diseases, but is distinctly different in its biological and pharmacokinetic profiles. We report that RVX-297 preferentially binds to the BD2 domains of the BET bromodomain and Extra Terminal (BET) family of protein. We demonstrate the differential binding modes of RVX-297 in BD1 and BD2 domains of BRD4 and BRD2 using X-ray crystallography, and describe the structural differences driving the BD2 selective binding of RVX-297. The isothermal titration calorimetry (ITC) data illustrate the related differential thermodynamics of binding of RVX-297 to single as well as dual BET bromodomains. - Highlights: • A novel inhibitor of BET bromodomains, RVX-297 is described. • The differential binding modes of RVX-297 in BD1 and BD2 domains of BRD4 and BRD2 using X-ray crystallography are described. • RVX-297 preferentially binds to the BD2 domains of the BET bromodomains. • The structural and thermodynamic properties of the BD2 selective binding of RVX-297 are characterized.

Steric Hindrance as a Basis for Structure-Based Design of Selective Inhibitors of Protein-Tyrosine Phosphatases

DEFF Research Database (Denmark)

Iversen, L. F.; Andersen, H. S.; Møller, K. B.

2001-01-01

Utilizing structure-based design, we have previously demonstrated that it is possible to obtain selective inhibitors of protein-tyrosine phosphatase 1B (PTP1B). A basic nitrogen was introduced into a general PTP inhibitor to form a salt bridge to Asp48 in PTP1B and simultaneously cause repulsion...... in PTPs containing an asparagine in the equivalent position [Iversen, L. F., et al. (2000) J. Biol. Chem. 275, 10300−10307]. Further, we have recently demonstrated that Gly259 in PTP1B forms the bottom of a gateway that allows easy access to the active site for a broad range of substrates, while bulky...... in accessibility to the active site among various PTPs. We show that a general, low-molecular weight PTP inhibitor can be developed into a highly selective inhibitor for PTP1B and TC-PTP by introducing a substituent, which is designed to address the region around residues 258 and 259. Detailed enzyme kinetic...

JAK inhibitors suppress t(8;21) fusion protein-induced leukemia

Science.gov (United States)

Lo, Miao-Chia; Peterson, Luke F.; Yan, Ming; Cong, Xiuli; Hickman, Justin H.; DeKelver, Russel C.; Niewerth, Denise; Zhang, Dong-Er

2014-01-01

Oncogenic mutations in components of the JAK/STAT pathway, including those in cytokine receptors and JAKs, lead to increased activity of downstream signaling and are frequently found in leukemia and other hematological disorders. Thus, small-molecule inhibitors of this pathway have been the focus of targeted therapy in these hematological diseases. We previously showed that t(8;21) fusion protein AML1-ETO and its alternatively spliced variant AML1-ETO9a (AE9a) enhance the JAK/STAT pathway via down-regulation of CD45, a negative regulator of this pathway. To investigate the therapeutic potential of targeting JAK/STAT in t(8;21) leukemia, we examined the effects of a JAK2-selective inhibitor TG101209 and a JAK1/2-selective inhibitor INCB18424 on t(8;21) leukemia cells. TG101209 and INCB18424 inhibited proliferation and promoted apoptosis of these cells. Furthermore, TG101209 treatment in AE9a leukemia mice reduced tumor burden and significantly prolonged survival. TG101209 also significantly impaired the leukemia-initiating potential of AE9a leukemia cells in secondary recipient mice. These results demonstrate the potential therapeutic efficacy of JAK inhibitors in treating t(8;21) AML. PMID:23812420

Targeting Transcriptional Addictions in Small Cell Lung Cancer with a Covalent CDK7 Inhibitor

DEFF Research Database (Denmark)

Christensen, Camilla L; Kwiatkowski, Nicholas; Abraham, Brian J

2014-01-01

Small cell lung cancer (SCLC) is an aggressive disease with high mortality, and the identification of effective pharmacological strategies to target SCLC biology represents an urgent need. Using a high-throughput cellular screen of a diverse chemical library, we observe that SCLC is sensitive...... to transcription-targeting drugs, in particular to THZ1, a recently identified covalent inhibitor of cyclin-dependent kinase 7. We find that expression of super-enhancer-associated transcription factor genes, including MYC family proto-oncogenes and neuroendocrine lineage-specific factors, is highly vulnerability...

Ibrutinib is an irreversible molecular inhibitor of ITK driving a Th1-selective pressure in T lymphocytes

Science.gov (United States)

Dubovsky, Jason A.; Beckwith, Kyle A.; Natarajan, Gayathri; Woyach, Jennifer A.; Jaglowski, Samantha; Zhong, Yiming; Hessler, Joshua D.; Liu, Ta-Ming; Chang, Betty Y.; Larkin, Karilyn M.; Stefanovski, Matthew R.; Chappell, Danielle L.; Frissora, Frank W.; Smith, Lisa L.; Smucker, Kelly A.; Flynn, Joseph M.; Jones, Jeffrey A.; Andritsos, Leslie A.; Maddocks, Kami; Lehman, Amy M.; Furman, Richard; Sharman, Jeff; Mishra, Anjali; Caligiuri, Michael A.; Satoskar, Abhay R.; Buggy, Joseph J.; Muthusamy, Natarajan; Johnson, Amy J.

2013-01-01

Given its critical role in T-cell signaling, interleukin-2–inducible kinase (ITK) is an appealing therapeutic target that can contribute to the pathogenesis of certain infectious, autoimmune, and neoplastic diseases. Ablation of ITK subverts Th2 immunity, thereby potentiating Th1-based immune responses. While small-molecule ITK inhibitors have been identified, none have demonstrated clinical utility. Ibrutinib is a confirmed irreversible inhibitor of Bruton tyrosine kinase (BTK) with outstanding clinical activity and tolerability in B-cell malignancies. Significant homology between BTK and ITK alongside in silico docking studies support ibrutinib as an immunomodulatory inhibitor of both ITK and BTK. Our comprehensive molecular and phenotypic analysis confirms ITK as an irreversible T-cell target of ibrutinib. Using ibrutinib clinical trial samples along with well-characterized neoplastic (chronic lymphocytic leukemia), parasitic infection (Leishmania major), and infectious disease (Listeria monocytogenes) models, we establish ibrutinib as a clinically relevant and physiologically potent ITK inhibitor with broad therapeutic utility. This trial was registered at www.clinicaltrials.gov as #NCT01105247 and #NCT01217749. PMID:23886836

Ibrutinib is an irreversible molecular inhibitor of ITK driving a Th1-selective pressure in T lymphocytes.

Science.gov (United States)

Dubovsky, Jason A; Beckwith, Kyle A; Natarajan, Gayathri; Woyach, Jennifer A; Jaglowski, Samantha; Zhong, Yiming; Hessler, Joshua D; Liu, Ta-Ming; Chang, Betty Y; Larkin, Karilyn M; Stefanovski, Matthew R; Chappell, Danielle L; Frissora, Frank W; Smith, Lisa L; Smucker, Kelly A; Flynn, Joseph M; Jones, Jeffrey A; Andritsos, Leslie A; Maddocks, Kami; Lehman, Amy M; Furman, Richard; Sharman, Jeff; Mishra, Anjali; Caligiuri, Michael A; Satoskar, Abhay R; Buggy, Joseph J; Muthusamy, Natarajan; Johnson, Amy J; Byrd, John C

2013-10-10

Given its critical role in T-cell signaling, interleukin-2-inducible kinase (ITK) is an appealing therapeutic target that can contribute to the pathogenesis of certain infectious, autoimmune, and neoplastic diseases. Ablation of ITK subverts Th2 immunity, thereby potentiating Th1-based immune responses. While small-molecule ITK inhibitors have been identified, none have demonstrated clinical utility. Ibrutinib is a confirmed irreversible inhibitor of Bruton tyrosine kinase (BTK) with outstanding clinical activity and tolerability in B-cell malignancies. Significant homology between BTK and ITK alongside in silico docking studies support ibrutinib as an immunomodulatory inhibitor of both ITK and BTK. Our comprehensive molecular and phenotypic analysis confirms ITK as an irreversible T-cell target of ibrutinib. Using ibrutinib clinical trial samples along with well-characterized neoplastic (chronic lymphocytic leukemia), parasitic infection (Leishmania major), and infectious disease (Listeria monocytogenes) models, we establish ibrutinib as a clinically relevant and physiologically potent ITK inhibitor with broad therapeutic utility. This trial was registered at www.clinicaltrials.gov as #NCT01105247 and #NCT01217749.

Substrate-derived triazolo- and azapeptides as inhibitors of cathepsins K and S.

Science.gov (United States)

Galibert, Matthieu; Wartenberg, Mylène; Lecaille, Fabien; Saidi, Ahlame; Mavel, Sylvie; Joulin-Giet, Alix; Korkmaz, Brice; Brömme, Dieter; Aucagne, Vincent; Delmas, Agnès F; Lalmanach, Gilles

2018-01-20

Cathepsin (Cat) K is a critical bone-resorbing protease and is a relevant target for the treatment of osteoporosis and bone metastasis, while CatS is an attractive target for drugs in autoimmune diseases (e.g. rheumatoid arthritis), emphysema or neuropathic pain. Despite major achievements, current pharmacological inhibitors are still lacking in safety and may have damaging side effects. A promising strategy for developing safer reversible and competitive inhibitors as new lead compounds could be to insert non-cleavable bonds at the scissile P1-P1' position of selective substrates of CatS and CatK. Accordingly, we introduced a 1,4-disubstituted 1,2,3-triazole heterocycle that mimics most of the features of a trans-amide bond, or we incorporated a semicarbazide bond (azaGly residue) by replacing the α-carbon of the glycyl residue at P1 by a nitrogen atom. AzaGly-containing peptidomimetics inhibited powerfully their respective target proteases in the nM range, while triazolopeptides were weaker inhibitors (Ki in the μM range). The selectivity of the azaGly CatS inhibitor (1b) was confirmed by using spleen lysates from wild-type vs CatS-deficient mice. Alternatively, the azaGly bradykinin-derived CatK inhibitor (2b) potently inhibited CatK (Ki = 9 nM) and impaired its kininase activity in vitro. Molecular modeling studies support that the semicarbazide bond of 2b is more favorable than the 1,2,3-triazole linkage of the bradykinin-derived pseudopeptide 2a to preserve an effective affinity towards CatK, its protease target. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

A selective phosphodiesterase 10A inhibitor reduces l-dopa-induced dyskinesias in parkinsonian monkeys.

Science.gov (United States)

Beck, Goichi; Maehara, Shunsuke; Chang, Phat Ly; Papa, Stella M

2018-03-06

Phosphodiesterase 10A is a member of the phosphodiesterase family whose brain expression is restricted to the striatum. Phosphodiesterase 10A regulates cyclic adenosine monophosphate and cyclic guanosine monophosphate, which mediate responses to dopamine receptor activation, and the levels of these cyclic nucleotides are decreased in experimental models of l-dopa-induced dyskinesia. The elevation of cyclic adenosine monophosphate/cyclic guanosine monophosphate levels by phosphodiesterase 10A inhibition may thus be targeted to reduce l-dopa-induced dyskinesia. The present study was aimed at determining the potential antidyskinetic effects of phosphodiesterase 10A inhibitors in a primate model of Parkinson's disease (PD). The experiments performed in this model were also intended to provide translational data for the design of future clinical trials. Five MPTP-treated macaques with advanced parkinsonism and reproducible l-dopa-induced dyskinesia were used. MR1916, a selective phosphodiesterase 10A inhibitor, at doses 0.0015 to 0.05 mg/kg, subcutaneously, or its vehicle (control test) was coadministered with l-dopa methyl ester acutely (predetermined optimal and suboptimal subcutaneous doses) and oral l-dopa chronically as daily treatment for 5 weeks. Standardized scales were used to assess motor disability and l-dopa-induced dyskinesia by blinded examiners. Pharmacokinetics was also examined. MR1916 consistently reduced l-dopa-induced dyskinesia in acute tests of l-dopa optimal and suboptimal doses. Significant effects were present with every MR1916 dose tested, but the most effective was 0.015 mg/kg. None of the MR1916 doses tested affected the antiparkinsonian action of l-dopa at the optimal dose. The anti-l-dopa-induced dyskinesia effect of MR1916 (0.015 mg/kg, subcutaneously) was sustained with chronic administration, indicating that tolerance did not develop over the 5-week treatment. No adverse effects were observed after MR1916 administration acutely or

Potent and Selective Peptidyl Boronic Acid Inhibitors of the Serine Protease Prostate-Specific Antigen

Science.gov (United States)

LeBeau, Aaron M.; Singh, Pratap; Isaacs, John T.; Denmeade, Samuel R.

2012-01-01

SUMMARY Prostate cancer cells produce high (microgram to milligram/milliliter) levels of the serine protease Prostate-Specific Antigen (PSA). PSA is enzymatically active in the extracellular fluid surrounding prostate cancers but is found at 1,000- to 10,000-fold lower concentrations in the circulation, where it is inactivated due to binding to abundant serum protease inhibitors. The exclusive presence of high levels of active PSA within prostate cancer sites makes PSA an attractive candidate for targeted imaging and therapeutics. A synthetic approach based on a peptide substrate identified first peptide aldehyde and then boronic acid inhibitors of PSA. The best of these had the sequence Cbz-Ser-Ser-Lys-Leu-(boro)Leu, with a Ki for PSA of 65 nM. The inhibitor had a 60-fold higher Ki for chymotrypsin. A validated model of PSA’s catalytic site confirmed the critical interactions between the inhibitor and residues within the PSA enzyme. PMID:18635003

Discovery of Fungal Denitrification Inhibitors by Targeting Copper Nitrite Reductase from Fusarium oxysporum.

Science.gov (United States)

Matsuoka, Masaki; Kumar, Ashutosh; Muddassar, Muhammad; Matsuyama, Akihisa; Yoshida, Minoru; Zhang, Kam Y J

2017-02-27

The efficient application of nitrogenous fertilizers is urgently required, as their excessive and inefficient use is causing substantial economic loss and environmental pollution. A significant amount of applied nitrogen in agricultural soils is lost as nitrous oxide (N 2 O) in the environment due to the microbial denitrification process. The widely distributed fungus Fusarium oxysporum is a major denitrifier in agricultural soils and its denitrification activity could be targeted to reduce nitrogen loss in the form of N 2 O from agricultural soils. Here, we report the discovery of first small molecule inhibitors of copper nitrite reductase (NirK) from F. oxysporum, which is a key enzyme in the fungal denitrification process. The inhibitors were discovered by a hierarchical in silico screening approach consisting of pharmacophore modeling and molecular docking. In vitro evaluation of F. oxysporum NirK activity revealed several pyrimidone and triazinone based compounds with potency in the low micromolar range. Some of these compounds suppressed the fungal denitrification in vivo as well. The compounds reported here could be used as starting points for the development of nitrogenous fertilizer supplements and coatings as a means to prevent nitrogen loss by targeting fungal denitrification.

A bioavailable cathepsin S nitrile inhibitor abrogates tumor development.

Science.gov (United States)

Wilkinson, Richard D A; Young, Andrew; Burden, Roberta E; Williams, Rich; Scott, Christopher J

2016-04-21

Cathepsin S has been implicated in a variety of malignancies with genetic ablation studies demonstrating a key role in tumor invasion and neo-angiogenesis. Thus, the application of cathepsin S inhibitors may have clinical utility in the treatment of cancer. In this investigation, we applied a cell-permeable dipeptidyl nitrile inhibitor of cathepsin S, originally developed to target cathepsin S in inflammatory diseases, in both in vitro and in vivo tumor models. Validation of cathepsin S selectivity was carried out by assaying fluorogenic substrate turnover using recombinant cathepsin protease. Complete kinetic analysis was carried out and true K i values calculated. Abrogation of tumour invasion using murine MC38 and human MCF7 cell lines were carried out in vitro using a transwell migration assay. Effect on endothelial tube formation was evaluated using primary HUVEC cells. The effect of inhibitor in vivo on MC38 and MCF7 tumor progression was evaluated using cells propagated in C57BL/6 and BALB/c mice respectively. Subsequent immunohistochemical staining of proliferation (Ki67) and apoptosis (TUNEL) was carried out on MCF7 tumors. We confirmed that this inhibitor was able to selectively target cathepsin S over family members K, V, L and B. The inhibitor also significantly reduced MC38 and MCF7 cell invasion and furthermore, significantly reduced HUVEC endothelial tubule formation in vitro. In vivo analysis revealed that the compound could significantly reduce tumor volume in murine MC38 syngeneic and MCF7 xenograft models. Immunohistochemical analysis of MCF7 tumors revealed cathepsin S inhibitor treatment significantly reduced proliferation and increased apoptosis. In summary, these results highlight the characterisation of this nitrile cathepsin S inhibitor using in vitro and in vivo tumor models, presenting a compound which may be used to further dissect the role of cathepsin S in cancer progression and may hold therapeutic potential.

Effects of tryptophan depletion on selective serotonin reuptake inhibitor-remitted patients with obsessive compulsive disorder.

Science.gov (United States)

Hood, Sean D; Broyd, Annabel; Robinson, Hayley; Lee, Jessica; Hudaib, Abdul-Rahman; Hince, Dana A

2017-12-01

Serotonergic antidepressants are first-line medication therapies for obsessive-compulsive disorder, however it is not known if synaptic serotonin availability is important for selective serotonin reuptake inhibitor efficacy. The present study tested the hypothesis that temporary reduction in central serotonin transmission, through acute tryptophan depletion, would result in an increase in anxiety in selective serotonin reuptake inhibitor-remitted obsessive-compulsive disorder patients. Eight patients (four males) with obsessive-compulsive disorder who showed sustained clinical improvement with selective serotonin reuptake inhibitor treatment underwent acute tryptophan depletion in a randomized, double-blind, placebo-controlled, within-subjects design, over two days one week apart. Five hours after consumption of the depleting/sham drink the participants performed a personalized obsessive-compulsive disorder symptom exposure task. Psychological responses were measured using the Spielberger State Anxiety Inventory, Yale-Brown Obsessive Compulsive Scale and Visual Analogue Scales. Free plasma tryptophan to large neutral amino acid ratio decreased by 93% on the depletion day and decreased by 1% on the sham day, as anticipated. Psychological rating scores as measured by Visual Analogue Scale showed a significant decrease in perceived control and increase in interfering thoughts at the time of provocation on the depletion day but not on the sham day. A measure of convergent validity, namely Visual Analogue Scale Similar to past, was significantly higher at the time of provocation on both the depletion and sham days. Both the depletion and time of provocation scores for Visual Analogue Scale Anxiety, Spielberger State Anxiety Inventory, Yale-Brown Obsessive Compulsive Scale and blood pressure were not significant. Acute tryptophan depletion caused a significant decrease in perceived control and increase in interfering thoughts at the time of provocation. Acute tryptophan

Structure-Activity Relationships of Pentacyclic Triterpenoids as Potent and Selective Inhibitors against Human Carboxylesterase 1

Directory of Open Access Journals (Sweden)

Li-Wei Zou

2017-06-01

Full Text Available Human carboxylesterase 1 (hCE1, one of the most important serine hydrolases distributed in liver and adipocytes, plays key roles in endobiotic homeostasis and xenobiotic metabolism. This study aimed to find potent and selective inhibitors against hCE1 from phytochemicals and their derivatives. To this end, a series of natural triterpenoids were collected and their inhibitory effects against human carboxylesterases (hCEs were assayed using D-Luciferin methyl ester (DME and 6,8-dichloro-9,9-dimethyl-7-oxo-7,9-dihydroacridin-2-yl benzoate (DDAB as specific optical substrate for hCE1, and hCE2, respectively. Following screening of a series of natural triterpenoids, oleanolic acid (OA, and ursolic acid (UA were found with strong inhibitory effects on hCE1 and relative high selectivity over hCE2. In order to get the highly selective and potent inhibitors of hCE1, a series of OA and UA derivatives were synthesized from OA and UA by chemical modifications including oxidation, reduction, esterification, and amidation. The inhibitory effects of these derivatives on hCEs were assayed and the structure-activity relationships of tested triterpenoids as hCE1 inhibitors were carefully investigated. The results demonstrated that the carbonyl group at the C-28 site is essential for hCE1 inhibition, the modifications of OA or UA at this site including esters, amides and alcohols are unbeneficial for hCE1 inhibition. In contrast, the structural modifications on OA and UA at other sites, such as converting the C-3 hydroxy group to 3-O-β-carboxypropionyl (compounds 20 and 22, led to a dramatically increase of the inhibitory effects against hCE1 and very high selectivity over hCE2. 3D-QSAR analysis of all tested triterpenoids including OA and UA derivatives provide new insights into the fine relationships linking between the inhibitory effects on hCE1 and the steric-electrostatic properties of triterpenoids. Furthermore, both inhibition kinetic analyses and docking

Modelling of potentially promising SARS protease inhibitors

International Nuclear Information System (INIS)

Plewczynski, Dariusz; Hoffmann, Marcin; Grotthuss, Marcin von; Knizewski, Lukasz; Rychewski, Leszek; Eitner, Krystian; Ginalski, Krzysztof

2007-01-01

In many cases, at the beginning of a high throughput screening experiment some information about active molecules is already available. Active compounds (such as substrate analogues, natural products and inhibitors of related proteins) are often identified in low throughput validation studies on a biochemical target. Sometimes the additional structural information is also available from crystallographic studies on protein and ligand complexes. In addition, the structural or sequence similarity of various protein targets yields a novel possibility for drug discovery. Co-crystallized compounds from homologous proteins can be used to design leads for a new target without co-crystallized ligands. In this paper we evaluate how far such an approach can be used in a real drug campaign, with severe acute respiratory syndrome (SARS) coronavirus providing an example. Our method is able to construct small molecules as plausible inhibitors solely on the basis of the set of ligands from crystallized complexes of a protein target, and other proteins from its structurally homologous family. The accuracy and sensitivity of the method are estimated here by the subsequent use of an electronic high throughput screening flexible docking algorithm. The best performing ligands are then used for a very restrictive similarity search for potential inhibitors of the SARS protease within the million compounds from the Ligand.Info small molecule meta-database. The selected molecules can be passed on for further experimental validation

Modelling of potentially promising SARS protease inhibitors

Energy Technology Data Exchange (ETDEWEB)

Plewczynski, Dariusz [Interdisciplinary Centre for Mathematical and Computational Modelling, ICM, Warsaw University, Pawinskiego 5a Street, 02-106 Warsaw (Poland); Hoffmann, Marcin [BioInfoBank Institute, Limanowskiego 24A/16, 60-744 Poznan (Poland); Grotthuss, Marcin von [BioInfoBank Institute, Limanowskiego 24A/16, 60-744 Poznan (Poland); Knizewski, Lukasz [Interdisciplinary Centre for Mathematical and Computational Modelling, ICM, Warsaw University, Pawinskiego 5a Street, 02-106 Warsaw (Poland); Rychewski, Leszek [BioInfoBank Institute, Limanowskiego 24A/16, 60-744 Poznan (Poland); Eitner, Krystian [BioInfoBank Institute, Limanowskiego 24A/16, 60-744 Poznan (Poland); Ginalski, Krzysztof [Interdisciplinary Centre for Mathematical and Computational Modelling, ICM, Warsaw University, Pawinskiego 5a Street, 02-106 Warsaw (Poland)

2007-07-18

In many cases, at the beginning of a high throughput screening experiment some information about active molecules is already available. Active compounds (such as substrate analogues, natural products and inhibitors of related proteins) are often identified in low throughput validation studies on a biochemical target. Sometimes the additional structural information is also available from crystallographic studies on protein and ligand complexes. In addition, the structural or sequence similarity of various protein targets yields a novel possibility for drug discovery. Co-crystallized compounds from homologous proteins can be used to design leads for a new target without co-crystallized ligands. In this paper we evaluate how far such an approach can be used in a real drug campaign, with severe acute respiratory syndrome (SARS) coronavirus providing an example. Our method is able to construct small molecules as plausible inhibitors solely on the basis of the set of ligands from crystallized complexes of a protein target, and other proteins from its structurally homologous family. The accuracy and sensitivity of the method are estimated here by the subsequent use of an electronic high throughput screening flexible docking algorithm. The best performing ligands are then used for a very restrictive similarity search for potential inhibitors of the SARS protease within the million compounds from the Ligand.Info small molecule meta-database. The selected molecules can be passed on for further experimental validation.

Approved and Experimental Small-Molecule Oncology Kinase Inhibitor Drugs: A Mid-2016 Overview.

Science.gov (United States)

Fischer, Peter M

2017-03-01

Kinase inhibitor research is a comparatively recent branch of medicinal chemistry and pharmacology and the first small-molecule kinase inhibitor, imatinib, was approved for clinical use only 15 years ago. Since then, 33 more kinase inhibitor drugs have received regulatory approval for the treatment of a variety of cancers and the volume of reports on the discovery and development of kinase inhibitors has increased to an extent where it is now difficult-even for those working in the field-easily to keep an overview of the compounds that are being developed, as currently there are 231 such compounds, targeting 38 different protein and lipid kinases (not counting isoforms), in clinical use or under clinical investigation. The purpose of this review is thus to provide an overview of the biomedical rationales for the kinases being targeted on the one hand, and the design principles, as well as chemical, pharmacological, pharmaceutical, and toxicological kinase inhibitor properties, on the other hand. Two issues that are especially important in kinase inhibitor research, target selectivity and drug resistance, as well as the underlying structural concepts, are discussed in general terms and in the context of relevant kinases and their inhibitors. © 2016 Wiley Periodicals, Inc.

[Recent Advances and Prospect of Advanced Non-small Cell Lung Cancer Targeted 
Therapy: Focus on Small Molecular Tyrosine Kinase Inhibitors].

Science.gov (United States)

Zhang, Guowei; Wang, Huijuan; Ma, Zhiyong

2017-04-20

At present the treatment of advanced non-small cell lung cancer enters a targeted era and develops rapidly. New drugs appear constantly. Small molecular tyrosine kinase inhibitors have occupied the biggest piece of the territory, which commonly have a clear biomarker as predictor, and show remarkable effect in specific molecular classification of patients. The epidermal growth factor tyrosine kinase inhibitors such as gefitinib, erlotinib, icotinib and anaplastic lymphoma kinase tyrosine kinase inhibitors crizotinib have brought a milestone advance. In recent years new generations of tyrosine kinase inhibitors have achieved a great success in patients with acquired resistance to the above two kinds of drugs. At the same time new therapeutic targets are constantly emerging. So in this paper, we reviewed and summarized the important drugs and clinical trails on this topic, and made a prospect of the future development.

Recent Advances and Prospect of Advanced Non-small Cell Lung Cancer Targeted 
Therapy: Focus on Small Molecular Tyrosine Kinase Inhibitors

Directory of Open Access Journals (Sweden)

Guowei ZHANG

2017-04-01

Full Text Available At present the treatment of advanced non-small cell lung cancer enters a targeted era and develops rapidly. New drugs appear constantly. Small molecular tyrosine kinase inhibitors have occupied the biggest piece of the territory, which commonly have a clear biomarker as predictor, and show remarkable effect in specific molecular classification of patients. The epidermal growth factor tyrosine kinase inhibitors such as gefitinib, erlotinib, icotinib and anaplastic lymphoma kinase tyrosine kinase inhibitors crizotinib have brought a milestone advance. In recent years new generations of tyrosine kinase inhibitors have achieved a great success in patients with acquired resistance to the above two kinds of drugs. At the same time new therapeutic targets are constantly emerging. So in this paper, we reviewed and summarized the important drugs and clinical trails on this topic, and made a prospect of the future development.

THINK OUTSIDE THE COLOR BOX: PROBABILISTIC TARGET SELECTION AND THE SDSS-XDQSO QUASAR TARGETING CATALOG

International Nuclear Information System (INIS)

Bovy, Jo; Hogg, David W.; Weaver, Benjamin A.; Hennawi, Joseph F.; Myers, Adam D.; Kirkpatrick, Jessica A.; Schlegel, David J.; Ross, Nicholas P.; Sheldon, Erin S.; McGreer, Ian D.; Schneider, Donald P.

2011-01-01

We present the SDSS-XDQSO quasar targeting catalog for efficient flux-based quasar target selection down to the faint limit of the Sloan Digital Sky Survey (SDSS) catalog, even at medium redshifts (2.5 ∼ 3.5) quasar probabilities for all 160,904,060 point sources with dereddened i-band magnitude between 17.75 and 22.45 mag in the 14,555 deg 2 of imaging from SDSS Data Release 8. The catalog can be used to define a uniformly selected and efficient low- or medium-redshift quasar survey, such as that needed for the SDSS-III's Baryon Oscillation Spectroscopic Survey project. We show that the XDQSO technique performs as well as the current best photometric quasar-selection technique at low redshift, and outperforms all other flux-based methods for selecting the medium-redshift quasars of our primary interest. We make code to reproduce the XDQSO quasar target selection publicly available.

Think Outside The Color Box: Probabilistic Target Selection And The SDSS-XDQSO Quasar Targeting Catalog

International Nuclear Information System (INIS)

Bovy, J.; Sheldon, E.; Hennawi, J.F.; Hogg, D.W.; Myers, A.D.

2011-01-01

We present the SDSS-XDQSO quasar targeting catalog for efficient flux-based quasar target selection down to the faint limit of the Sloan Digital Sky Survey (SDSS) catalog, even at medium redshifts (2.5 ∼ 3.5) quasar probabilities for all 160,904,060 point sources with dereddened i-band magnitude between 17.75 and 22.45 mag in the 14,555 deg 2 of imaging from SDSS Data Release 8. The catalog can be used to define a uniformly selected and efficient low- or medium-redshift quasar survey, such as that needed for the SDSS-III's Baryon Oscillation Spectroscopic Survey project. We show that the XDQSO technique performs as well as the current best photometric quasar-selection technique at low redshift, and outperforms all other flux-based methods for selecting the medium-redshift quasars of our primary interest. We make code to reproduce the XDQSO quasar target selection publicly available.

A concise total synthesis of (R)-fluoxetine, a potent and selective serotonin reuptake inhibitor

International Nuclear Information System (INIS)

Fatima, Angelo de; Lapis, Alexandre Augusto M.; Pilli, Ronaldo A.

2005-01-01

(R)-Fluoxetine, potent and selective serotonin reuptake inhibitor, has been synthesized in six steps, 50% overall yield and 99% ee from benzaldehyde via catalytic asymmetric allylation with Maruoka's catalyst. (author)

Lipid raft-like liposomes used for targeted delivery of a chimeric entry-inhibitor peptide with anti-HIV-1 activity.

Science.gov (United States)

Gómara, María José; Pérez-Pomeda, Ignacio; Gatell, José María; Sánchez-Merino, Victor; Yuste, Eloisa; Haro, Isabel

2017-02-01

The work reports the design and synthesis of a chimeric peptide that is composed of the peptide sequences of two entry inhibitors which target different sites of HIV-1 gp41. The chimeric peptide offers the advantage of targeting two gp41 regions simultaneously: the fusion peptide and the loop both of which are membrane active and participate in the membrane fusion process. We therefore use lipid raft-like liposomes as a tool to specifically direct the chimeric inhibitor peptide to the membrane domains where the HIV-1 envelope protein is located. Moreover, the liposomes that mimic the viral membrane composition protect the chimeric peptide against proteolytic digestion thereby increasing the stability of the peptide. The described liposome preparations are suitable nanosystems for managing hydrophobic entry-inhibitor peptides as putative therapeutics. Copyright © 2016 Elsevier Inc. All rights reserved.

Small-Molecule Inhibitors Targeting DNA Repair and DNA Repair Deficiency in Research and Cancer Therapy.

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Hengel, Sarah R; Spies, M Ashley; Spies, Maria

2017-09-21

To maintain stable genomes and to avoid cancer and aging, cells need to repair a multitude of deleterious DNA lesions, which arise constantly in every cell. Processes that support genome integrity in normal cells, however, allow cancer cells to develop resistance to radiation and DNA-damaging chemotherapeutics. Chemical inhibition of the key DNA repair proteins and pharmacologically induced synthetic lethality have become instrumental in both dissecting the complex DNA repair networks and as promising anticancer agents. The difficulty in capitalizing on synthetically lethal interactions in cancer cells is that many potential targets do not possess well-defined small-molecule binding determinates. In this review, we discuss several successful campaigns to identify and leverage small-molecule inhibitors of the DNA repair proteins, from PARP1, a paradigm case for clinically successful small-molecule inhibitors, to coveted new targets, such as RAD51 recombinase, RAD52 DNA repair protein, MRE11 nuclease, and WRN DNA helicase. Copyright © 2017 Elsevier Ltd. All rights reserved.

A high throughput screening assay for identifying glycation inhibitors on MALDI-TOF target.

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Zhang, Qiuting; Tu, Zongcai; Wang, Hui; Fan, Liangliang; Huang, Xiaoqin; Xiao, Hui

2015-03-01

The Maillard reaction plays an important role in the food industry, however, the deleterious effects generated by the advanced glycation end-products (AGEs) have been well recognized. Many efforts have been made to seek new AGE inhibitors, in particular those natural ones without adverse effect. We have developed a rapid, mass spectrometry based, on-plate screening assay for novel AGE inhibitors. The glycation reaction, inhibition feedback as well as the subsequent MALDI mass spectrometric analysis occurred on one single MALDI plate. At 1:10 M ratio of peptide to sugar, as little as 4h incubation time allowed the screening test to be ready for analysis. DSP, inhibition and IC50 were calculated to evaluate selected inhibitors and resulting inhibition efficiencies were consistent with available references. We demonstrated that this method provide a potential high throughput screening assay to analyze and identify the anti-glycation agents. Copyright © 2014 Elsevier Ltd. All rights reserved.

Synergistic targeting of malignant pleural mesothelioma cells by MDM2 inhibitors and TRAIL agonists

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Urso, Loredana; Biasini, Lorena; Zago, Giulia; Calabrese, Fiorella; Conte, Pier Franco; Ciminale, Vincenzo; Pasello, Giulia

2017-01-01

Malignant Pleural Mesothelioma (MPM) is a chemoresistant tumor characterized by low rate of p53 mutation and upregulation of Murine Double Minute 2 (MDM2), suggesting that it may be effectively targeted using MDM2 inhibitors. In the present study, we investigated the anticancer activity of the MDM2 inhibitors Nutlin 3a (in vitro) and RG7112 (in vivo), as single agents or in combination with rhTRAIL. In vitro studies were performed using MPM cell lines derived from epithelioid (ZL55, M14K), biphasic (MSTO211H) and sarcomatoid (ZL34) MPMs. In vivo studies were conducted on a sarcomatoid MPM mouse model. In all the cell lines tested (with the exception of ZL55, which carries a biallelic loss-of-function mutation of p53), Nutlin 3a enhanced p21, MDM2 and DR5 expression, and decreased survivin expression. These changes were associated to cell cycle arrest but not to a significant induction of apoptosis. A synergistic pro-apoptotic effect was obtained through the association of rhTRAIL in all the cell lines harboring functional p53. This synergistic interaction of MDM2 inhibitor and TRAIL agonist was confirmed using a mouse preclinical model. Our results suggest that the combined targeting of MDM2 and TRAIL might provide a novel therapeutic option for treatment of MPM patients, particularly in the case of sarcomatoid MPM with MDM2 overexpression and functional inactivation of wild-type p53. PMID:28562336

Identification and characterization of carprofen as a multi-target FAAH/COX inhibitor

Science.gov (United States)

Favia, Angelo D.; Habrant, Damien; Scarpelli, Rita; Migliore, Marco; Albani, Clara; Bertozzi, Sine Mandrup; Dionisi, Mauro; Tarozzo, Glauco; Piomelli, Daniele; Cavalli, Andrea; De Vivo, Marco

2013-01-01

Pain and inflammation are major therapeutic areas for drug discovery. Current drugs for these pathologies have limited efficacy, however, and often cause a number of unwanted side effects. In the present study, we identify the non-steroid anti-inflammatory drug, carprofen, as a multi-target-directed ligand that simultaneously inhibits cyclooxygenase-1 (COX-1), COX-2 and fatty acid amide hydrolase (FAAH). Additionally, we synthesized and tested several racemic derivatives of carprofen, sharing this multi-target activity. This may result in improved analgesic efficacy and reduced side effects (Naidu, et al (2009) J Pharmacol Exp Ther 329, 48-56; Fowler, C.J. et al. (2012) J Enzym Inhib Med Chem Jan 6; Sasso, et al (2012) Pharmacol Res 65, 553). The new compounds are among the most potent multi-target FAAH/COXs inhibitors reported so far in the literature, and thus may represent promising starting points for the discovery of new analgesic and anti-inflammatory drugs. PMID:23043222

A concise total synthesis of (R)-fluoxetine, a potent and selective serotonin reuptake inhibitor

Energy Technology Data Exchange (ETDEWEB)

Fatima, Angelo de; Lapis, Alexandre Augusto M.; Pilli, Ronaldo A. [Universidade Estadual de Campinas, SP (Brazil). Inst. de Quimica]. E-mail: pilli@iqm.unicamp.br

2005-05-15

(R)-Fluoxetine, potent and selective serotonin reuptake inhibitor, has been synthesized in six steps, 50% overall yield and 99% ee from benzaldehyde via catalytic asymmetric allylation with Maruoka's catalyst. (author)

A novel dimeric inhibitor targeting Beta2GPI in Beta2GPI/antibody complexes implicated in antiphospholipid syndrome.

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Alexey Kolyada

2010-12-01

Full Text Available β2GPI is a major antigen for autoantibodies associated with antiphospholipid syndrome (APS, an autoimmune disease characterized by thrombosis and recurrent pregnancy loss. Only the dimeric form of β2GPI generated by anti-β2GPI antibodies is pathologically important, in contrast to monomeric β2GPI which is abundant in plasma.We created a dimeric inhibitor, A1-A1, to selectively target β2GPI in β2GPI/antibody complexes. To make this inhibitor, we isolated the first ligand-binding module from ApoER2 (A1 and connected two A1 modules with a flexible linker. A1-A1 interferes with two pathologically important interactions in APS, the binding of β2GPI/antibody complexes with anionic phospholipids and ApoER2. We compared the efficiency of A1-A1 to monomeric A1 for inhibition of the binding of β2GPI/antibody complexes to anionic phospholipids. We tested the inhibition of β2GPI present in human serum, β2GPI purified from human plasma and the individual domain V of β2GPI. We demonstrated that when β2GPI/antibody complexes are formed, A1-A1 is much more effective than A1 in inhibition of the binding of β2GPI to cardiolipin, regardless of the source of β2GPI. Similarly, A1-A1 strongly inhibits the binding of dimerized domain V of β2GPI to cardiolipin compared to the monomeric A1 inhibitor. In the absence of anti-β2GPI antibodies, both A1-A1 and A1 only weakly inhibit the binding of pathologically inactive monomeric β2GPI to cardiolipin.Our results suggest that the approach of using a dimeric inhibitor to block β2GPI in the pathological multivalent β2GPI/antibody complexes holds significant promise. The novel inhibitor A1-A1 may be a starting point in the development of an effective therapeutic for antiphospholipid syndrome.

A Novel Dimeric Inhibitor Targeting Beta2GPI in Beta2GPI/Antibody Complexes Implicated in Antiphospholipid Syndrome

Energy Technology Data Exchange (ETDEWEB)

A Kolyada; C Lee; A De Biasio; N Beglova

2011-12-31

{beta}2GPI is a major antigen for autoantibodies associated with antiphospholipid syndrome (APS), an autoimmune disease characterized by thrombosis and recurrent pregnancy loss. Only the dimeric form of {beta}2GPI generated by anti-{beta}2GPI antibodies is pathologically important, in contrast to monomeric {beta}2GPI which is abundant in plasma. We created a dimeric inhibitor, A1-A1, to selectively target {beta}2GPI in {beta}2GPI/antibody complexes. To make this inhibitor, we isolated the first ligand-binding module from ApoER2 (A1) and connected two A1 modules with a flexible linker. A1-A1 interferes with two pathologically important interactions in APS, the binding of {beta}2GPI/antibody complexes with anionic phospholipids and ApoER2. We compared the efficiency of A1-A1 to monomeric A1 for inhibition of the binding of {beta}2GPI/antibody complexes to anionic phospholipids. We tested the inhibition of {beta}2GPI present in human serum, {beta}2GPI purified from human plasma and the individual domain V of {beta}2GPI. We demonstrated that when {beta}2GPI/antibody complexes are formed, A1-A1 is much more effective than A1 in inhibition of the binding of {beta}2GPI to cardiolipin, regardless of the source of {beta}2GPI. Similarly, A1-A1 strongly inhibits the binding of dimerized domain V of {beta}2GPI to cardiolipin compared to the monomeric A1 inhibitor. In the absence of anti-{beta}2GPI antibodies, both A1-A1 and A1 only weakly inhibit the binding of pathologically inactive monomeric {beta}2GPI to cardiolipin. Our results suggest that the approach of using a dimeric inhibitor to block {beta}2GPI in the pathological multivalent {beta}2GPI/antibody complexes holds significant promise. The novel inhibitor A1-A1 may be a starting point in the development of an effective therapeutic for antiphospholipid syndrome.

Targeting TORC1/2 Enhances Sensitivity to EGFR Inhibitors in Head and Neck Cancer Preclinical Models

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Andre Cassell

2012-11-01

Full Text Available Head and neck squamous cell carcinoma (HNSCC is characterized by overexpression of the epidermal growth factor receptor (EGFR where treatments targeting EGFR have met with limited clinical success. Elucidation of the key downstream-pathways that remain activated in the setting of EGFR blockade may reveal new therapeutic targets. The present study was undertaken to test the hypothesis that inhibition of the mammalian target of rapamycin (mTOR complex would enhance the effects of EGFR blockade in HNSCC preclinical models. Treatment of HNSCC cell lines with the newly developed TORC1/TORC2 inhibitor OSI-027/ASP4876 resulted in dose-dependent inhibition of proliferation with abrogation of phosphorylation of known downstream targets including phospho-AKT (Ser473, phospho-4E-BP1, phospho-p70s6K, and phospho-PRAS40. Furthermore, combined treatment with OSI-027 and erlotinib resulted in enhanced biochemical effects and synergistic growth inhibition in vitro. Treatment of mice bearing HNSCC xenografts with a combination of the Food and Drug Administration (FDA-approved EGFR inhibitor cetuximab and OSI-027 demonstrated a significant reduction of tumor volumes compared with either treatment alone. These findings suggest that TORC1/TORC2 inhibition in conjunction with EGFR blockade represents a plausible therapeutic strategy for HNSCC.

Targeting TORC1/2 enhances sensitivity to EGFR inhibitors in head and neck cancer preclinical models.

Science.gov (United States)

Cassell, Andre; Freilino, Maria L; Lee, Jessica; Barr, Sharon; Wang, Lin; Panahandeh, Mary C; Thomas, Sufi M; Grandis, Jennifer R

2012-11-01

Head and neck squamous cell carcinoma (HNSCC) is characterized by overexpression of the epidermal growth factor receptor (EGFR) where treatments targeting EGFR have met with limited clinical success. Elucidation of the key downstream-pathways that remain activated in the setting of EGFR blockade may reveal new therapeutic targets. The present study was undertaken to test the hypothesis that inhibition of the mammalian target of rapamycin (mTOR) complex would enhance the effects of EGFR blockade in HNSCC preclinical models. Treatment of HNSCC cell lines with the newly developed TORC1/TORC2 inhibitor OSI-027/ASP4876 resulted in dose-dependent inhibition of proliferation with abrogation of phosphorylation of known downstream targets including phospho-AKT (Ser473), phospho-4E-BP1, phospho-p70s6K, and phospho-PRAS40. Furthermore, combined treatment with OSI-027 and erlotinib resulted in enhanced biochemical effects and synergistic growth inhibition in vitro. Treatment of mice bearing HNSCC xenografts with a combination of the Food and Drug Administration (FDA)-approved EGFR inhibitor cetuximab and OSI-027 demonstrated a significant reduction of tumor volumes compared with either treatment alone. These findings suggest that TORC1/TORC2 inhibition in conjunction with EGFR blockade represents a plausible therapeutic strategy for HNSCC.

The effect of selective serotonin reuptake inhibitors in healthy subjects. A systematic review

DEFF Research Database (Denmark)

Knorr, Ulla; Kessing, Lars Vedel; Knorr, Ulla

2010-01-01

BACKGROUND: Selective serotonin reuptake inhibitors (SSRIs) show antidepressant properties in many patients with a diagnosis of depression. An understanding of the underlying mechanisms of the effect of SSRIs in healthy patients may lead to an understanding of the yet unclear pathophysiology of d...

Increased Bleeding Risk With Concurrent Use of Selective Serotonin Reuptake inhibitors and Coumarins

NARCIS (Netherlands)

Schalekamp, Tom; Klungel, Olaf H; Souverein, Patrick C; de Boer, Anthonius

2008-01-01

BACKGROUND: Treatment with vitamin K antagonists (coumarins) is associated with an increased risk of bleeding. Because use of selective serotonin reuptake inhibitors (SSRIs) is also associated with an increased risk of bleeding, we assessed the odds ratio (OR) of abnormal bleeding associated with

Diverse inhibitor chemotypes targeting Trypanosoma cruzi CYP51.

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Shamila S Gunatilleke

Full Text Available Chagas Disease, a WHO- and NIH-designated neglected tropical disease, is endemic in Latin America and an emerging infection in North America and Europe as a result of population moves. Although a major cause of morbidity and mortality due to heart failure, as well as inflicting a heavy economic burden in affected regions, Chagas Disease elicits scant notice from the pharmaceutical industry because of adverse economic incentives. The discovery and development of new routes to chemotherapy for Chagas Disease is a clear priority.The similarity between the membrane sterol requirements of pathogenic fungi and those of the parasitic protozoon Trypanosoma cruzi, the causative agent of Chagas human cardiopathy, has led to repurposing anti-fungal azole inhibitors of sterol 14α-demethylase (CYP51 for the treatment of Chagas Disease. To diversify the therapeutic pipeline of anti-Chagasic drug candidates we exploited an approach that included directly probing the T. cruzi CYP51 active site with a library of synthetic small molecules. Target-based high-throughput screening reduced the library of ∼104,000 small molecules to 185 hits with estimated nanomolar K(D values, while cross-validation against T. cruzi-infected skeletal myoblast cells yielded 57 active hits with EC(50 <10 µM. Two pools of hits partially overlapped. The top hit inhibited T. cruzi with EC(50 of 17 nM and was trypanocidal at 40 nM.The hits are structurally diverse, demonstrating that CYP51 is a rather permissive enzyme target for small molecules. Cheminformatic analysis of the hits suggests that CYP51 pharmacology is similar to that of other cytochromes P450 therapeutic targets, including thromboxane synthase (CYP5, fatty acid ω-hydroxylases (CYP4, 17α-hydroxylase/17,20-lyase (CYP17 and aromatase (CYP19. Surprisingly, strong similarity is suggested to glutaminyl-peptide cyclotransferase, which is unrelated to CYP51 by sequence or structure. Lead compounds developed by pharmaceutical

A selective HDAC 1/2 inhibitor modulates chromatin and gene expression in brain and alters mouse behavior in two mood-related tests.

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Frederick A Schroeder

Full Text Available Psychiatric diseases, including schizophrenia, bipolar disorder and major depression, are projected to lead global disease burden within the next decade. Pharmacotherapy, the primary--albeit often ineffective--treatment method, has remained largely unchanged over the past 50 years, highlighting the need for novel target discovery and improved mechanism-based treatments. Here, we examined in wild type mice the impact of chronic, systemic treatment with Compound 60 (Cpd-60, a slow-binding, benzamide-based inhibitor of the class I histone deacetylase (HDAC family members, HDAC1 and HDAC2, in mood-related behavioral assays responsive to clinically effective drugs. Cpd-60 treatment for one week was associated with attenuated locomotor activity following acute amphetamine challenge. Further, treated mice demonstrated decreased immobility in the forced swim test. These changes are consistent with established effects of clinical mood stabilizers and antidepressants, respectively. Whole-genome expression profiling of specific brain regions (prefrontal cortex, nucleus accumbens, hippocampus from mice treated with Cpd-60 identified gene expression changes, including a small subset of transcripts that significantly overlapped those previously reported in lithium-treated mice. HDAC inhibition in brain was confirmed by increased histone acetylation both globally and, using chromatin immunoprecipitation, at the promoter regions of upregulated transcripts, a finding consistent with in vivo engagement of HDAC targets. In contrast, treatment with suberoylanilide hydroxamic acid (SAHA, a non-selective fast-binding, hydroxamic acid HDAC 1/2/3/6 inhibitor, was sufficient to increase histone acetylation in brain, but did not alter mood-related behaviors and had dissimilar transcriptional regulatory effects compared to Cpd-60. These results provide evidence that selective inhibition of HDAC1 and HDAC2 in brain may provide an epigenetic-based target for developing

High Potency of Indolyl Aryl Sulfone Nonnucleoside Inhibitors towards Drug-Resistant Human Immunodeficiency Virus Type 1 Reverse Transcriptase Mutants Is Due to Selective Targeting of Different Mechanistic Forms of the Enzyme

Science.gov (United States)

Cancio, Reynel; Silvestri, Romano; Ragno, Rino; Artico, Marino; De Martino, Gabriella; La Regina, Giuseppe; Crespan, Emmanuele; Zanoli, Samantha; Hübscher, Ulrich; Spadari, Silvio; Maga, Giovanni

2005-01-01

Indolyl aryl sulfone (IAS) nonnucleoside inhibitors have been shown to potently inhibit the growth of wild-type and drug-resistant human immunodeficiency virus type 1 (HIV-1), but their exact mechanism of action has not been elucidated yet. Here, we describe the mechanism of inhibition of HIV-1 reverse transcriptase (RT) by selected IAS derivatives. Our results showed that, depending on the substitutions introduced in the IAS common pharmacophore, these compounds can be made selective for different enzyme-substrate complexes. Moreover, we showed that the molecular basis for this selectivity was a different association rate of the drug to a particular enzymatic form along the reaction pathway. By comparing the activities of the different compounds against wild-type RT and the nonnucleoside reverse transcriptase inhibitor-resistant mutant Lys103Asn, it was possible to hypothesize, on the basis of their mechanism of action, a rationale for the design of drugs which could overcome the steric barrier imposed by the Lys103Asn mutation. PMID:16251294

Human HDAC isoform selectivity achieved via exploitation of the acetate release channel with structurally unique small molecule inhibitors

Energy Technology Data Exchange (ETDEWEB)

Whitehead, Lewis; Dobler, Markus R.; Radetich, Branko; Zhu, Yanyi; Atadja, Peter W.; Claiborne, Tavina; Grob, Jonathan E.; McRiner, Andrew; Pancost, Margaret R.; Patnaik, Anup; Shao, Wenlin; Shultz, Michael; Tichkule, Ritesh; Tommasi, Ruben A.; Vash, Brian; Wang, Ping; Stams, Travis (Novartis)

2013-11-20

Herein we report the discovery of a family of novel yet simple, amino-acid derived class I HDAC inhibitors that demonstrate isoform selectivity via access to the internal acetate release channel. Isoform selectivity criteria is discussed on the basis of X-ray crystallography and molecular modeling of these novel inhibitors bound to HDAC8, potentially revealing insights into the mechanism of enzymatic function through novel structural features revealed at the atomic level.

Targeting Tumor-Associated Macrophages as a Potential Strategy to Enhance the Response to Immune Checkpoint Inhibitors.

Science.gov (United States)

Cassetta, Luca; Kitamura, Takanori

2018-01-01

Inhibition of immune checkpoint pathways in CD8 + T cell is a promising therapeutic strategy for the treatment of solid tumors that has shown significant anti-tumor effects and is now approved by the FDA to treat patients with melanoma and lung cancer. However the response to this therapy is limited to a certain fraction of patients and tumor types, for reasons still unknown. To ensure success of this treatment, CD8 + T cells, the main target of the checkpoint inhibitors, should exert full cytotoxicity against tumor cells. However recent studies show that tumor-associated macrophages (TAM) can impede this process by different mechanisms. In this mini-review we will summarize recent studies showing the effect of TAM targeting on immune checkpoint inhibitors efficacy. We will also discuss on the limitations of the current strategies as well on the future scientific challenges for the progress of the tumor immunology field.

Novel targeted agents for gastric cancer

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Liu Lian

2012-06-01

Full Text Available Abstract Contemporary advancements have had little impact on the treatment of gastric cancer (GC, the world’s second highest cause of cancer death. Agents targeting human epidermal growth factor receptor mediated pathways have been a common topic of contemporary cancer research, including monoclonal antibodies (mAbs and receptor tyrosine kinase inhibitors (TKIs. Trastuzumab is the first target agent evidencing improvements in overall survival in HER2-positive (human epidermal growth factor receptor 2 gastric cancer patients. Agents targeting vascular epithelial growth factor (VEGF, mammalian target of rapamycin (mTOR, and other biological pathways are also undergoing clinical trials, with some marginally positive results. Effective targeted therapy requires patient selection based on predictive molecular biomarkers. Most phase III clinical trials are carried out without patient selection; therefore, it is hard to achieve personalized treatment and to monitor patient outcome individually. The trend for future clinical trials requires patient selection methods based on current understanding of GC biology with the application of biomarkers.

GSK2586184, a JAK1 selective inhibitor, in two patients with ulcerative colitis

NARCIS (Netherlands)

de Vries, Leonie C. S.; Ludbrook, Valerie J.; Hicks, Kirsty J.; D'Haens, Geert R.

2017-01-01

Tofacitinib, a non-selective Janus kinase (JAK) inhibitor, is effective in inducing clinical and endoscopic remission in patients with active ulcerative colitis (UC). Tofacitinib inhibits cytokine signalling through blockade of JAK1, JAK2, JAK3 and tyrosine kinase 2 (TYK2). Adverse events including

WRN-targeted therapy using inhibitors NSC 19630 and NSC 617145 induce apoptosis in HTLV-1-transformed adult T-cell leukemia cells

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R. Moles

2016-11-01

Full Text Available Abstract Background Human T-cell leukemia virus type 1 (HTLV-1 infection is associated with adult T-cell leukemia/lymphoma (ATLL, a lymphoproliferative malignancy with a dismal prognosis and limited therapeutic options. Recent evidence shows that HTLV-1-transformed cells present defects in both DNA replication and DNA repair, suggesting that these cells might be particularly sensitive to treatment with a small helicase inhibitor. Because the “Werner syndrome ATP-dependent helicase” encoded by the WRN gene plays important roles in both cellular proliferation and DNA repair, we hypothesized that inhibition of WRN activity could be used as a new strategy to target ATLL cells. Methods Our analysis demonstrates an apoptotic effect induced by the WRN helicase inhibitor in HTLV-1-transformed cells in vitro and ATL-derived cell lines. Inhibition of cellular proliferation and induction of apoptosis were demonstrated with cell cycle analysis, XTT proliferation assay, clonogenic assay, annexin V staining, and measurement of mitochondrial transmembrane potential. Results Targeted inhibition of the WRN helicase induced cell cycle arrest and apoptosis in HTLV-1-transformed leukemia cells. Treatment with NSC 19630 (WRN inhibitor induces S-phase cell cycle arrest, disruption of the mitochondrial membrane potential, and decreased expression of anti-apoptotic factor Bcl-2. These events were associated with activation of caspase-3-dependent apoptosis in ATL cells. We identified some ATL cells, ATL-55T and LMY1, less sensitive to NSC 19630 but sensitive to another WRN inhibitor, NSC 617145. Conclusions WRN is essential for survival of ATL cells. Our studies suggest that targeting the WRN helicase with small inhibitors is a novel promising strategy to target HTLV-1-transformed ATL cells.

Prostate-specific membrane antigen targeted imaging and therapy of prostate cancer using a PSMA inhibitor as a homing ligand.

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Kularatne, Sumith A; Wang, Kevin; Santhapuram, Hari-Krishna R; Low, Philip S

2009-01-01

Prostate cancer (PCa) is a major cause of mortality and morbidity in Western society today. Current methods for detecting PCa are limited, leaving most early malignancies undiagnosed and sites of metastasis in advanced disease undetected. Major deficiencies also exist in the treatment of PCa, especially metastatic disease. In an effort to improve both detection and therapy of PCa, we have developed a PSMA-targeted ligand that delivers attached imaging and therapeutic agents selectively to PCa cells without targeting normal cells. The PSMA-targeted radioimaging agent (DUPA-(99m)Tc) was found to bind PSMA-positive human PCa cells (LNCaP cell line) with nanomolar affinity (K(D) = 14 nM). Imaging and biodistribution studies revealed that DUPA-(99m)Tc localizes primarily to LNCaP cell tumor xenografts in nu/nu mice (% injected dose/gram = 11.3 at 4 h postinjection; tumor-to-muscle ratio = 75:1). Two PSMA-targeted optical imaging agents (DUPA-FITC and DUPA-rhodamine B) were also shown to efficiently label PCa cells and to internalize and traffic to intracellular endosomes. A PSMA-targeted chemotherapeutic agent (DUPA-TubH) was demonstrated to kill PSMA-positive LNCaP cells in culture (IC(50) = 3 nM) and to eliminate established tumor xenografts in nu/nu mice with no detectable weight loss. Blockade of tumor targeting upon administration of excess PSMA inhibitor (PMPA) and the absence of targeting to PSMA-negative tumors confirmed the specificity of each of the above targeted reagents for PSMA. Tandem use of the imaging and therapeutic agents targeted to the same receptor could allow detection, staging, monitoring, and treatment of PCa with improved accuracy and efficacy.

In silico panning for a non-competitive peptide inhibitor

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Ikebukuro Kazunori

2007-01-01

Full Text Available Abstract Background Peptide ligands have tremendous therapeutic potential as efficacious drugs. Currently, more than 40 peptides are available in the market for a drug. However, since costly and time-consuming synthesis procedures represent a problem for high-throughput screening, novel procedures to reduce the time and labor involved in screening peptide ligands are required. We propose the novel approach of 'in silico panning' which consists of a two-stage screening, involving affinity selection by docking simulation and evolution of the peptide ligand using genetic algorithms (GAs. In silico panning was successfully applied to the selection of peptide inhibitor for water-soluble quinoprotein glucose dehydrogenase (PQQGDH. Results The evolution of peptide ligands for a target enzyme was achieved by combining a docking simulation with evolution of the peptide ligand using genetic algorithms (GAs, which mimic Darwinian evolution. Designation of the target area as next to the substrate-binding site of the enzyme in the docking simulation enabled the selection of a non-competitive inhibitor. In all, four rounds of selection were carried out on the computer; the distribution of the docking energy decreased gradually for each generation and improvements in the docking energy were observed over the four rounds of selection. One of the top three selected peptides with the lowest docking energy, 'SERG' showed an inhibitory effect with Ki value of 20 μM. PQQGDH activity, in terms of the Vmax value, was 3-fold lower than that of the wild-type enzyme in the presence of this peptide. The mechanism of the SERG blockage of the enzyme was identified as non-competitive inhibition. We confirmed the specific binding of the peptide, and its equilibrium dissociation constant (KD value was calculated as 60 μM by surface plasmon resonance (SPR analysis. Conclusion We demonstrate an effective methodology of in silico panning for the selection of a non

Targeting the PDGF-B/PDGFR-β Interface with Destruxin A5 to Selectively Block PDGF-BB/PDGFR-ββ Signaling and Attenuate Liver Fibrosis

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Xingqi Wang

2016-05-01

Full Text Available PDGF-BB/PDGFR-ββ signaling plays very crucial roles in the process of many diseases such as liver fibrosis. However, drug candidates with selective affinities for PDGF-B/PDGFR-β remain deficient. Here, we identified a natural cyclopeptide termed destruxin A5 that effectively inhibits PDGF-BB-induced PDGFR-β signaling. Interestingly and importantly, the inhibitory mechanism is distinct from the mechanism of tyrosine kinase inhibitors because destruxin A5 does not have the ability to bind to the ATP-binding pocket of PDGFR-β. Using Biacore T200 technology, thermal shift technology, microscale thermophoresis technology and computational analysis, we confirmed that destruxin A5 selectively targets the PDGF-B/PDGFR-β interaction interface to block this signaling. Additionally, the inhibitory effect of destruxin A5 on PDGF-BB/PDGFR-ββ signaling was verified using in vitro, ex vivo and in vivo models, in which the extent of liver fibrosis was effectively alleviated by destruxin A5. In summary, destruxin A5 may represent an efficacious and more selective inhibitor of PDGF-BB/PDGFR-ββ signaling.

Targeting of phage particles towards endothelial cells by antibodies selected through a multi-parameter selection strategy.

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Mandrup, Ole A; Lykkemark, Simon; Kristensen, Peter

2017-02-10

One of the hallmarks of cancer is sustained angiogenesis. Here, normal endothelial cells are activated, and their formation of new blood vessels leads to continued tumour growth. An improved patient condition is often observed when angiogenesis is prevented or normalized through targeting of these genomically stable endothelial cells. However, intracellular targets constitute a challenge in therapy, as the agents modulating these targets have to be delivered and internalized specifically to the endothelial cells. Selection of antibodies binding specifically to certain cell types is well established. It is nonetheless a challenge to ensure that the binding of antibodies to the target cell will mediate internalization. Previously selection of such antibodies has been performed targeting cancer cell lines; most often using either monovalent display or polyvalent display. In this article, we describe selections that isolate internalizing antibodies by sequential combining monovalent and polyvalent display using two types of helper phages, one which increases display valence and one which reduces background. One of the selected antibodies was found to mediate internalization into human endothelial cells, although our results confirms that the single stranded nature of the DNA packaged into phage particles may limit applications aimed at targeting nucleic acids in mammalian cells.

Protease inhibitors and indoleamines selectively inhibit cholinesterases in the histopathologic structures of Alzheimer disease.

Science.gov (United States)

Wright, C I; Guela, C; Mesulam, M M

1993-01-01

Neurofibrillary tangles and amyloid plaques express acetylcholinesterase and butyrylcholinesterase activity in Alzheimer disease. We previously reported that traditional acetylcholinesterase inhibitors such as BW284C51, tacrine, and physostigmine were more potent inhibitors of the acetylcholinesterase in normal axons and cell bodies than of the acetylcholinesterase in plaques and tangles. We now report that the reverse pattern is seen with indoleamines (such as serotonin and its precursor 5-hydroxytryptophan), carboxypeptidase inhibitor, and the nonspecific protease inhibitor bacitracin. These substances are more potent inhibitors of the cholinesterases in plaques and tangles than of those in normal axons and cell bodies. These results show that the enzymatic properties of plaque and tangle-associated cholinesterases diverge from those of normal axons and cell bodies. The selective susceptibility to bacitracin and carboxypeptidase inhibitor indicates that the catalytic sites of plaque and tangle-bound cholinesterases are more closely associated with peptidase or protease-like properties than the catalytic sites of cholinesterases in normal axons and cell bodies. This shift in enzymatic affinity may lead to the abnormal protein processing that is thought to play a major role in the pathogenesis of Alzheimer disease. The availability of pharmacological and dietary means for altering brain indoleamines raises therapeutic possibilities for inhibiting the abnormal cholinesterase activity associated with Alzheimer disease. Images PMID:8421706

A targeted enzyme approach to sensitization of tyrosine kinase inhibitor-resistant breast cancer cells.

Science.gov (United States)

Giordano, Courtney R; Mueller, Kelly L; Terlecky, Laura J; Krentz, Kendra A; Bollig-Fischer, Aliccia; Terlecky, Stanley R; Boerner, Julie L

2012-10-01

Gefitinib is an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) of potential use in patients with breast cancer. Unfortunately, in clinical studies, gefitinib is often ineffective indicating that resistance to EGFR inhibitors may be a common occurrence in cancer of the breast. EGFR has been shown to be overexpressed in breast cancer, and in particular remains hyperphosphorylated in cell lines such as MDA-MB-468 that are resistant to EGFR inhibitors. Here, we investigate the cause of this sustained phosphorylation and the molecular basis for the ineffectiveness of gefitinib. We show that reactive oxygen species (ROS), known to damage cellular macromolecules and to modulate signaling cascades in a variety of human diseases including cancers, appear to play a critical role in mediating EGFR TKI-resistance. Furthermore, elimination of these ROS through use of a cell-penetrating catalase derivative sensitizes the cells to gefitinib. These results suggest a new approach for the treatment of TKI-resistant breast cancer patients specifically, the targeting of ROS and attendant downstream oxidative stress and their effects on signaling cascades. Copyright © 2012. Published by Elsevier Inc.

Structure-based virtual screening of molecular libraries as cdk2 inhibitors

International Nuclear Information System (INIS)

Riaz, U.; Khaleeq, M.

2011-01-01

CDK2 inhibitor is an important target in multiple processes associated with tumor growth and development, including proliferation, neovascularization, and metastasis. In this study, hit identification was performed by virtual screening of commercial and in-house compound libraries. Docking studies for the hits were performed, and scoring functions were used to evaluate the docking results and to rank ligand-binding affinities. Subsequently, hit optimization for potent and selective candidate CDK2 inhibitors was performed through focused library design and docking analyses. Consequently, we report that a novel compound with an IC50 value of 89 nM, representing 2-Amino-4,6-di-(4',6'-dibromophenyl)pyrimidine 1, is highly selective for CDK2 inhibitors. The docking structure of compound 1 with CDK2 inhibitor disclosed that the NH moiety and pyrimidine ring appeared to fit tightly into the hydrophobic pocket of CDK2 inhibitor. Additionally, the pyrimidine NH forms a hydrogen bond with the carboxyl group of Asp348. These results confirm the successful application of virtual screening studies in the lead discovery process, and suggest that our novel compound can be an effective CDK2 inhibitor candidate for further lead optimization. (author)

Overview of CDK9 as a target in cancer research.

Science.gov (United States)

Morales, Fatima; Giordano, Antonio

2016-01-01

CDK9 is a protein in constant development in cancer therapy. Herein we present an overview of the enzyme as a target for cancer therapy. We provide data on its characteristics and mechanism of action. In recent years, CDK9 inhibitors that have been designed with molecular modeling have demonstrated good antitumoral activity in vitro. Clinical studies of the drugs flavopiridol, dinaciclib, seliciclib, SNS-032 and RGB-286638 used as CDK9 inhibitors are also reviewed, with their additional targets and their relative IC50 values. Unfortunately, treatment with these drugs remains unsuccessful and involves many adverse effects. We could conclude that there are many small molecules that bind to CDK9, but their lack of selectivity against other CDKs do not allow them to get to the clinical use. However, drug designers currently have the tools needed to improve the selectivity of CDK9 inhibitors and to make successful treatment available to patients.

QStatin, a Selective Inhibitor of Quorum Sensing in Vibrio Species

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Byoung Sik Kim

2018-01-01

Full Text Available Pathogenic Vibrio species cause diseases in diverse marine animals reared in aquaculture. Since their pathogenesis, persistence, and survival in marine environments are regulated by quorum sensing (QS, QS interference has attracted attention as a means to control these bacteria in aquatic settings. A few QS inhibitors of Vibrio species have been reported, but detailed molecular mechanisms are lacking. Here, we identified a novel, potent, and selective Vibrio QS inhibitor, named QStatin [1-(5-bromothiophene-2-sulfonyl-1H-pyrazole], which affects Vibrio harveyi LuxR homologues, the well-conserved master transcriptional regulators for QS in Vibrio species. Crystallographic and biochemical analyses showed that QStatin binds tightly to a putative ligand-binding pocket in SmcR, the LuxR homologue in V. vulnificus, and changes the flexibility of the protein, thereby altering its transcription regulatory activity. Transcriptome analysis revealed that QStatin results in SmcR dysfunction, affecting the expression of SmcR regulon required for virulence, motility/chemotaxis, and biofilm dynamics. Notably, QStatin attenuated representative QS-regulated phenotypes in various Vibrio species, including virulence against the brine shrimp (Artemia franciscana. Together, these results provide molecular insights into the mechanism of action of an effective, sustainable QS inhibitor that is less susceptible to resistance than other antimicrobial agents and useful in controlling the virulence of Vibrio species in aquacultures.

Targeting the Thioredoxin System for Cancer Therapy.

Science.gov (United States)

Zhang, Junmin; Li, Xinming; Han, Xiao; Liu, Ruijuan; Fang, Jianguo

2017-09-01

Thioredoxin (Trx) and thioredoxin reductase (TrxR) are essential components of the Trx system which plays pivotal roles in regulating multiple cellular redox signaling pathways. In recent years TrxR/Trx have been increasingly recognized as an important modulator of tumor development, and hence targeting TrxR/Trx is a promising strategy for cancer treatment. In this review we first discuss the structural details of TrxR, the functions of the Trx system, and the rational of targeting TrxR/Trx for cancer treatment. We also highlight small-molecule TrxR/Trx inhibitors that have potential anticancer activity and review their mechanisms of action. Finally, we examine the challenges of developing TrxR/Trx inhibitors as anticancer agents and perspectives for selectively targeting TrxR/Trx. Copyright © 2017 Elsevier Ltd. All rights reserved.

An algorithm for preferential selection of spectroscopic targets in LEGUE

International Nuclear Information System (INIS)

Carlin, Jeffrey L.; Newberg, Heidi Jo; Lépine, Sébastien; Deng Licai; Chen Yuqin; Fu Xiaoting; Gao Shuang; Li Jing; Liu Chao; Beers, Timothy C.; Christlieb, Norbert; Grillmair, Carl J.; Guhathakurta, Puragra; Han Zhanwen; Hou Jinliang; Lee, Hsu-Tai; Liu Xiaowei; Pan Kaike; Sellwood, J. A.; Wang Hongchi

2012-01-01

We describe a general target selection algorithm that is applicable to any survey in which the number of available candidates is much larger than the number of objects to be observed. This routine aims to achieve a balance between a smoothly-varying, well-understood selection function and the desire to preferentially select certain types of targets. Some target-selection examples are shown that illustrate different possibilities of emphasis functions. Although it is generally applicable, the algorithm was developed specifically for the LAMOST Experiment for Galactic Understanding and Exploration (LEGUE) survey that will be carried out using the Chinese Guo Shou Jing Telescope. In particular, this algorithm was designed for the portion of LEGUE targeting the Galactic halo, in which we attempt to balance a variety of science goals that require stars at fainter magnitudes than can be completely sampled by LAMOST. This algorithm has been implemented for the halo portion of the LAMOST pilot survey, which began in October 2011.

Potent and Selective BACE-1 Peptide Inhibitors Lower Brain Aβ Levels Mediated by Brain Shuttle Transport

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Nadine Ruderisch

2017-10-01

Full Text Available Therapeutic approaches to fight Alzheimer's disease include anti-Amyloidβ (Aβ antibodies and secretase inhibitors. However, the blood-brain barrier (BBB limits the brain exposure of biologics and the chemical space for small molecules to be BBB permeable. The Brain Shuttle (BS technology is capable of shuttling large molecules into the brain. This allows for new types of therapeutic modalities engineered for optimal efficacy on the molecular target in the brain independent of brain penetrating properties. To this end, we designed BACE1 peptide inhibitors with varying lipid modifications with single-digit picomolar cellular potency. Secondly, we generated active-exosite peptides with structurally confirmed dual binding mode and improved potency. When fused to the BS via sortase coupling, these BACE1 inhibitors significantly reduced brain Aβ levels in mice after intravenous administration. In plasma, both BS and non-BS BACE1 inhibitor peptides induced a significant time- and dose-dependent decrease of Aβ. Our results demonstrate that the BS is essential for BACE1 peptide inhibitors to be efficacious in the brain and active-exosite design of BACE1 peptide inhibitors together with lipid modification may be of therapeutic relevance.

Structural Bioinformatics-Based Prediction of Exceptional Selectivity of p38 MAP Kinase Inhibitor PH-797804

Energy Technology Data Exchange (ETDEWEB)

Xing, Li; Shieh, Huey S.; Selness, Shaun R.; Devraj, Rajesh V.; Walker, John K.; Devadas, Balekudru; Hope, Heidi R.; Compton, Robert P.; Schindler, John F.; Hirsch, Jeffrey L.; Benson, Alan G.; Kurumbail, Ravi G.; Stegeman, Roderick A.; Williams, Jennifer M.; Broadus, Richard M.; Walden, Zara; Monahan, Joseph B.; Pfizer

2009-07-24

PH-797804 is a diarylpyridinone inhibitor of p38{alpha} mitogen-activated protein (MAP) kinase derived from a racemic mixture as the more potent atropisomer (aS), first proposed by molecular modeling and subsequently confirmed by experiments. On the basis of structural comparison with a different biaryl pyrazole template and supported by dozens of high-resolution crystal structures of p38{alpha} inhibitor complexes, PH-797804 is predicted to possess a high level of specificity across the broad human kinase genome. We used a structural bioinformatics approach to identify two selectivity elements encoded by the TXXXG sequence motif on the p38{alpha} kinase hinge: (i) Thr106 that serves as the gatekeeper to the buried hydrophobic pocket occupied by 2,4-difluorophenyl of PH-797804 and (ii) the bidentate hydrogen bonds formed by the pyridinone moiety with the kinase hinge requiring an induced 180{sup o} rotation of the Met109-Gly110 peptide bond. The peptide flip occurs in p38{alpha} kinase due to the critical glycine residue marked by its conformational flexibility. Kinome-wide sequence mining revealed rare presentation of the selectivity motif. Corroboratively, PH-797804 exhibited exceptionally high specificity against MAP kinases and the related kinases. No cross-reactivity was observed in large panels of kinase screens (selectivity ratio of >500-fold). In cellular assays, PH-797804 demonstrated superior potency and selectivity consistent with the biochemical measurements. PH-797804 has met safety criteria in human phase I studies and is under clinical development for several inflammatory conditions. Understanding the rationale for selectivity at the molecular level helps elucidate the biological function and design of specific p38{alpha} kinase inhibitors.

In utero exposure to selective serotonin reuptake inhibitors and risk for autism spectrum disorder

DEFF Research Database (Denmark)

Gidaya, Nicole B; Lee, Brian K; Burstyn, Igor

2014-01-01

We investigated whether there is an association between increased risk for autism spectrum disorders (ASD) and selective serotonin reuptake inhibitors (SSRIs) used during pregnancy. This study used Denmark's health and population registers to obtain information regarding prescription drugs, ASD...

Small Molecule Screen for Candidate Antimalarials Targeting Plasmodium Kinesin-5*

Science.gov (United States)

Liu, Liqiong; Richard, Jessica; Kim, Sunyoung; Wojcik, Edward J.

2014-01-01

Plasmodium falciparum and vivax are responsible for the majority of malaria infections worldwide, resulting in over a million deaths annually. Malaria parasites now show measured resistance to all currently utilized drugs. Novel antimalarial drugs are urgently needed. The Plasmodium Kinesin-5 mechanoenzyme is a suitable “next generation” target. Discovered via small molecule screen experiments, the human Kinesin-5 has multiple allosteric sites that are “druggable.” One site in particular, unique in its sequence divergence across all homologs in the superfamily and even within the same family, exhibits exquisite drug specificity. We propose that Plasmodium Kinesin-5 shares this allosteric site and likewise can be targeted to uncover inhibitors with high specificity. To test this idea, we performed a screen for inhibitors selective for Plasmodium Kinesin-5 ATPase activity in parallel with human Kinesin-5. Our screen of nearly 2000 compounds successfully identified compounds that selectively inhibit both P. vivax and falciparum Kinesin-5 motor domains but, as anticipated, do not impact human Kinesin-5 activity. Of note is a candidate drug that did not biochemically compete with the ATP substrate for the conserved active site or disrupt the microtubule-binding site. Together, our experiments identified MMV666693 as a selective allosteric inhibitor of Plasmodium Kinesin-5; this is the first identified protein target for the Medicines of Malaria Venture validated collection of parasite proliferation inhibitors. This work demonstrates that chemical screens against human kinesins are adaptable to homologs in disease organisms and, as such, extendable to strategies to combat infectious disease. PMID:24737313

Target Selection for the SDSS-III MARVELS Survey

Science.gov (United States)

Paegert, Martin; Stassun, Keivan G.; De Lee, Nathan; Pepper, Joshua; Fleming, Scott W.; Sivarani, Thirupathi; Mahadevan, Suvrath; Mack, Claude E., III; Dhital, Saurav; Hebb, Leslie; Ge, Jian

2015-06-01

We present the target selection process for the Multi-object APO Radial Velocity Exoplanets Large-area Survey (MARVELS), which is part of the Sloan Digital Sky Survey (SDSS) III. MARVELS is a medium-resolution (R ∼ 11,000) multi-fiber spectrograph capable of obtaining radial velocities for 60 objects at a time in order to find brown dwarfs and giant planets. The survey was configured to target dwarf stars with effective temperatures approximately between 4500 and 6250 K. For the first 2 years MARVELS relied on low-resolution spectroscopic pre-observations to estimate the effective temperature and log (g) for candidate stars and then selected suitable dwarf stars from this pool. Ultimately, the pre-observation spectra proved ineffective at filtering out giant stars; many giants were incorrectly classified as dwarfs, resulting in a giant contamination rate of ∼30% for the first phase of the MARVELS survey. Thereafter, the survey instead applied a reduced proper motion cut to eliminate giants and used the Infrared Flux Method to estimate effective temperatures, using only extant photmetric and proper-motion catalog information. The target selection method introduced here may be useful for other surveys that need to rely on extant catalog data for selection of specific stellar populations.

Computational methods for analysis and inference of kinase/inhibitor relationships

Directory of Open Access Journals (Sweden)

Fabrizio eFerrè

2014-06-01

Full Text Available The central role of kinases in virtually all signal transduction networks is the driving motivation for the development of compounds modulating their activity. ATP-mimetic inhibitors are essential tools for elucidating signaling pathways and are emerging as promising therapeutic agents. However, off-target ligand binding and complex and sometimes unexpected kinase/inhibitor relationships can occur for seemingly unrelated kinases, stressing that computational approaches are needed for learning the interaction determinants and for the inference of the effect of small compounds on a given kinase. Recently published high-throughput profiling studies assessed the effects of thousands of small compound inhibitors, covering a substantial portion of the kinome. This wealth of data paved the road for computational resources and methods that can offer a major contribution in understanding the reasons of the inhibition, helping in the rational design of more specific molecules, in the in silico prediction of inhibition for those neglected kinases for which no systematic analysis has been carried yet, in the selection of novel inhibitors with desired selectivity, and offering novel avenues of personalized therapies.

Inhibitors of steroidal cytochrome p450 enzymes as targets for drug development.

Science.gov (United States)

Baston, Eckhard; Leroux, Frédéric R

2007-01-01

Cytochrome P450's are enzymes which catalyze a large number of biological reactions, for example hydroxylation, N-, O-, S- dealkylation, epoxidation or desamination. Their substrates include fatty acids, steroids or prostaglandins. In addition, a high number of various xenobiotics are metabolized by these enzymes. The enzyme 17alpha-hydroxylase-C17,20-lyase (P450(17), CYP 17, androgen synthase), a cytochrome P450 monooxygenase, is the key enzyme for androgen biosynthesis. It catalyzes the last step of the androgen biosynthesis in the testes and adrenal glands and produces androstenedione and dehydroepiandrosterone from progesterone and pregnenolone. The microsomal enzyme aromatase (CYP19) transforms these androgens to estrone and estradiol. Estrogens stimulate tumor growth in hormone dependent breast cancer. In addition, about 80 percent of prostate cancers are androgen dependent. Selective inhibitors of these enzymes are thus important alternatives to treatment options like antiandrogens or antiestrogens. The present article deals with recent patents (focus on publications from 2000 - 2006) concerning P450 inhibitor design where steroidal substrates are involved. In this context a special focus is provided for CYP17 and CYP19. Mechanisms of action will also be discussed. Inhibitors of CYP11B2 (aldosterone synthase) will also be dealt with.

Targeting TORC1/2 Enhances Sensitivity to EGFR Inhibitors in Head and Neck Cancer Preclinical Models1

Science.gov (United States)

Cassell, Andre; Freilino, Maria L; Lee, Jessica; Barr, Sharon; Wang, Lin; Panahandeh, Mary C; Thomas, Sufi M; Grandis, Jennifer R

2012-01-01

Head and neck squamous cell carcinoma (HNSCC) is characterized by overexpression of the epidermal growth factor receptor (EGFR) where treatments targeting EGFR have met with limited clinical success. Elucidation of the key downstream-pathways that remain activated in the setting of EGFR blockade may reveal new therapeutic targets. The present study was undertaken to test the hypothesis that inhibition of the mammalian target of rapamycin (mTOR) complex would enhance the effects of EGFR blockade in HNSCC preclinical models. Treatment of HNSCC cell lines with the newly developed TORC1/TORC2 inhibitor OSI-027/ASP4876 resulted in dose-dependent inhibition of proliferation with abrogation of phosphorylation of known downstream targets including phospho-AKT (Ser473), phospho-4E-BP1, phospho-p70s6K, and phospho-PRAS40. Furthermore, combined treatment with OSI-027 and erlotinib resulted in enhanced biochemical effects and synergistic growth inhibition in vitro. Treatment of mice bearing HNSCC xenografts with a combination of the Food and Drug Administration (FDA)-approved EGFR inhibitor cetuximab and OSI-027 demonstrated a significant reduction of tumor volumes compared with either treatment alone. These findings suggest that TORC1/TORC2 inhibition in conjunction with EGFR blockade represents a plausible therapeutic strategy for HNSCC. PMID:23226094

Target-selected mutagenesis of the rat

NARCIS (Netherlands)

Smits, B.M.; Mudde, J.B.; Plasterk, R.; Cuppen, E.

2004-01-01

The rat is one of the most extensively studied model organisms, and with its genome being sequenced, tools to manipulate gene function in vivo have become increasingly important. We here report proof of principle for target-selected mutagenesis as a reverse genetic or knockout approach for the rat.

Selective inhibition of Biotin Protein Ligase from Staphylococcus aureus*

Science.gov (United States)

Soares da Costa, Tatiana P.; Tieu, William; Yap, Min Y.; Pendini, Nicole R.; Polyak, Steven W.; Sejer Pedersen, Daniel; Morona, Renato; Turnidge, John D.; Wallace, John C.; Wilce, Matthew C. J.; Booker, Grant W.; Abell, Andrew D.

2012-01-01

There is a well documented need to replenish the antibiotic pipeline with new agents to combat the rise of drug resistant bacteria. One strategy to combat resistance is to discover new chemical classes immune to current resistance mechanisms that inhibit essential metabolic enzymes. Many of the obvious drug targets that have no homologous isozyme in the human host have now been investigated. Bacterial drug targets that have a closely related human homologue represent a new frontier in antibiotic discovery. However, to avoid potential toxicity to the host, these inhibitors must have very high selectivity for the bacterial enzyme over the human homolog. We have demonstrated that the essential enzyme biotin protein ligase (BPL) from the clinically important pathogen Staphylococcus aureus could be selectively inhibited. Linking biotin to adenosine via a 1,2,3 triazole yielded the first BPL inhibitor selective for S. aureus BPL over the human equivalent. The synthesis of new biotin 1,2,3-triazole analogues using click chemistry yielded our most potent structure (Ki 90 nm) with a >1100-fold selectivity for the S. aureus BPL over the human homologue. X-ray crystallography confirmed the mechanism of inhibitor binding. Importantly, the inhibitor showed cytotoxicity against S. aureus but not cultured mammalian cells. The biotin 1,2,3-triazole provides a novel pharmacophore for future medicinal chemistry programs to develop this new antibiotic class. PMID:22437830

Selective inhibition of biotin protein ligase from Staphylococcus aureus.

Science.gov (United States)

Soares da Costa, Tatiana P; Tieu, William; Yap, Min Y; Pendini, Nicole R; Polyak, Steven W; Sejer Pedersen, Daniel; Morona, Renato; Turnidge, John D; Wallace, John C; Wilce, Matthew C J; Booker, Grant W; Abell, Andrew D

2012-05-18

There is a well documented need to replenish the antibiotic pipeline with new agents to combat the rise of drug resistant bacteria. One strategy to combat resistance is to discover new chemical classes immune to current resistance mechanisms that inhibit essential metabolic enzymes. Many of the obvious drug targets that have no homologous isozyme in the human host have now been investigated. Bacterial drug targets that have a closely related human homologue represent a new frontier in antibiotic discovery. However, to avoid potential toxicity to the host, these inhibitors must have very high selectivity for the bacterial enzyme over the human homolog. We have demonstrated that the essential enzyme biotin protein ligase (BPL) from the clinically important pathogen Staphylococcus aureus could be selectively inhibited. Linking biotin to adenosine via a 1,2,3 triazole yielded the first BPL inhibitor selective for S. aureus BPL over the human equivalent. The synthesis of new biotin 1,2,3-triazole analogues using click chemistry yielded our most potent structure (K(i) 90 nM) with a >1100-fold selectivity for the S. aureus BPL over the human homologue. X-ray crystallography confirmed the mechanism of inhibitor binding. Importantly, the inhibitor showed cytotoxicity against S. aureus but not cultured mammalian cells. The biotin 1,2,3-triazole provides a novel pharmacophore for future medicinal chemistry programs to develop this new antibiotic class.

Peptide-targeted, stimuli-responsive polymersomes for delivering a cancer stemness inhibitor to cancer stem cell microtumors.

Science.gov (United States)

Karandish, Fataneh; Froberg, James; Borowicz, Pawel; Wilkinson, John C; Choi, Yongki; Mallik, Sanku

2018-03-01

Often cancer relapses after an initial response to chemotherapy because of the tumor's heterogeneity and the presence of progenitor stem cells, which can renew. To overcome drug resistance, metastasis, and relapse in cancer, a promising approach is the inhibition of cancer stemness. In this study, the expression of the neuropilin-1 receptor in both pancreatic and prostate cancer stem cells was identified and targeted with a stimuli-responsive, polymeric nanocarrier to deliver a stemness inhibitor (napabucasin) to cancer stem cells. Reduction-sensitive amphiphilic block copolymers PEG 1900 -S-S-PLA 6000 and the N 3 -PEG 1900 -PLA 6000 were synthesized. The tumor penetrating iRGD peptide-hexynoic acid conjugate was linked to the N 3 -PEG 1900 -PLA 6000 polymer via a Cu 2+ catalyzed "Click" reaction. Subsequently, this peptide-polymer conjugate was incorporated into polymersomes for tumor targeting and tissue penetration. We prepared polymersomes containing 85% PEG 1900 -S-S-PLA 6000 , 10% iRGD-polymer conjugate, and 5% DPPE-lissamine rhodamine dye. The iRGD targeted polymersomes encapsulating the cancer stemness inhibitor napabucasin were internalized in both prostate and pancreatic cancer stem cells. The napabucasin encapsulated polymersomes significantly (p < .05) reduced the viability of both prostate and pancreatic cancer stem cells and decreased the stemness protein expression notch-1 and nanog compared to the control and vesicles without any drug. The napabucasin encapsulated polymersome formulations have the potential to lead to a new direction in prostate and pancreatic cancer therapy by penetrating deeply into the tumors, releasing the encapsulated stemness inhibitor, and killing cancer stem cells. Copyright © 2017 Elsevier B.V. All rights reserved.

Target Therapy Using a Small Molecule Inhibitor against Angiogenic Receptors in Pancreatic Cancer

Directory of Open Access Journals (Sweden)

Peter Büchler

2007-02-01

Full Text Available PURPOSE: PD173074, a small molecule inhibitor of VEGF-RII and FGF-RI, targets neoangiogenesis and mitogenesis. This study aimed to analyze a singlecompound-driven inhibition of FGF and VEGF receptors in pancreatic cancer. EXPERIMENTAL DESIGN: RT-PCR and Western blots were performed to quantify protein expression and phosphorylation. Anchorage dependent and independent growth assays were used to study cell growth. With flow cytometry, cell cycle analysis and apoptosis were studied. In vivo HPAF-II and MIA PaCa-2 cells were xenografted. Animals were treated daily for 10 weeks. Immunohistochemistry was used to quantify microvessel density and apoptosis. RESULTS: Highest levels of FGF-RI were detectable in MIA PaCa-2 cells, lowest in HPAF-II cells. PD173074 inhibited cell growth most prominently in cells expressing high levels of FGF-RI. Cell cycle progression was inhibited by blocking transition in the G0/G1 phase, and consequently, apoptosis was increased. In vivo significant inhibition of orthotopic tumor growth was achieved by a combination effect of inhibition of mitogenesis, induction of apoptosis, and reduction of angiogenesis in PD173074-treated animals. CONCLUSIONS: These data highlight VEGF-RII and FGF-RI as therapeutic targets and suggest a potential role for the combined use of tyrosine kinase inhibitors in the management of inoperable pancreatic cancer patients.

In silico design and biological evaluation of a dual specificity kinase inhibitor targeting cell cycle progression and angiogenesis.

Science.gov (United States)

Latham, Antony M; Kankanala, Jayakanth; Fearnley, Gareth W; Gage, Matthew C; Kearney, Mark T; Homer-Vanniasinkam, Shervanthi; Wheatcroft, Stephen B; Fishwick, Colin W G; Ponnambalam, Sreenivasan

2014-01-01

Protein kinases play a central role in tumor progression, regulating fundamental processes such as angiogenesis, proliferation and metastasis. Such enzymes are an increasingly important class of drug target with small molecule kinase inhibitors being a major focus in drug development. However, balancing drug specificity and efficacy is problematic with off-target effects and toxicity issues. We have utilized a rational in silico-based approach to demonstrate the design and study of a novel compound that acts as a dual inhibitor of vascular endothelial growth factor receptor 2 (VEGFR2) and cyclin-dependent kinase 1 (CDK1). This compound acts by simultaneously inhibiting pro-angiogenic signal transduction and cell cycle progression in primary endothelial cells. JK-31 displays potent in vitro activity against recombinant VEGFR2 and CDK1/cyclin B proteins comparable to previously characterized inhibitors. Dual inhibition of the vascular endothelial growth factor A (VEGF-A)-mediated signaling response and CDK1-mediated mitotic entry elicits anti-angiogenic activity both in an endothelial-fibroblast co-culture model and a murine ex vivo model of angiogenesis. We deduce that JK-31 reduces the growth of both human endothelial cells and human breast cancer cells in vitro. This novel synthetic molecule has broad implications for development of similar multi-kinase inhibitors with anti-angiogenic and anti-cancer properties. In silico design is an attractive and innovative method to aid such drug discovery.

Preliminary in vitro and in vivo assessment of a new targeted inhibitor for choroidal neovascularization in age-related macular degeneration

Directory of Open Access Journals (Sweden)

Li W

2016-10-01

Full Text Available Wenbo Li,1,* Lijie Dong,1,* Minwang Ma,2,* Bojie Hu,1 Zhenyu Lu,3 Xun Liu,1 Juping Liu,1 Xiaorong Li1 1Tianjin Medical University Eye Hospital, Tianjin, People’s Republic of China; 2Affiliated Hospital of Medical College of Chinese People’s Armed Police Forces (CapF, Tianjin, People’s Republic of China; 3Tianjin Precision Cell Biotechnology Co. Ltd., Tianjin, People’s Republic of China *These authors contributed equally to this work Abstract: Choroidal neovascularization (CNV in age-related macular degeneration usually causes blindness. We established a novel targeted inhibitor for CNV in age-related macular degeneration. The inhibitor CR2-sFlt 1 comprises a CR2-targeting fragment and an anti-vascular endothelial growth factor (VEGF domain (sFlt 1. The targeting of CR2-sFlt 1 was studied using the transwell assay in vitro and frozen sections in vivo using green fluorescent labeling. Trans­well assay results showed that CR2-sFlt 1 migrated to the interface of complement activation products and was present in the retinal tissue of the CR2-sFlt 1-treated CNV mice. Treatment effects were assessed by investigating the VEGF concentration in retinal pigmented epithelial cell medium and the thickness of the CNV complex in the mice treated with CR2-sFlt 1. CR2-sFlt 1 significantly reduced the VEGF secretion from retinal pigmented epithelial cells in vitro and retarded CNV progress in a mouse model. Expression analysis of VEGF and VEGFRs after CR2-sFlt 1 intervention indicated the existence of feedback mechanisms in exogenous CR2-sFlt 1, endogenous VEGF, and VEGFR interaction. In summary, we demonstrated for the first time that using CR2-sFlt 1 could inhibit CNV with clear targeting and high selectivity. Keywords: choroidal neovascularization, macular degeneration, complement activation, vascular endothelial growth factor

Side Effects of Nitrification Inhibitors on Non Target Microbial Processes in Soils

Directory of Open Access Journals (Sweden)

Johannes Carl Gottlieb Ottow

2011-01-01

Full Text Available Agricultural chemicals have been used extensively in modern agriculture and toxicological studies suggest a great potential for inducing undesirable effects on non target organisms. A model experiment was conducted in order to determine side effects of three nitrification inhibitors (NIs, 3,4dimethylpyrazolephosphate = DMPP, 4-Chlor-methylpyrazole phosphate = ClMPP and dicyandiamide = DCD on non target microbial processes in soils. Side effects and dose response curve of three NIs were quantified under laboratory conditions using silty clay, loam and a sandy soils. Dehydrogenase, dimethylsulfoxide reductase as well as nitrogenase activity (NA and potential denitrification capacity were measured as common and specific non target microbial processes. The influence of 5-1000 times the base concentration, dose response curves were examined, and no observable effect level = NOEL, as well as effective dose ED10 and ED50 (10% and 50% inhibition were calculated. The NOEL for microbial non target processes were about 30–70 times higher than base concentration in all investigated soils. The potential denitrification capacity revealed to be the most sensitive parameter. ClMPP exhibited the strongest influence on the non target microbial processes in the three soils. The NOEL, ED10 and ED50 values were higher in clay than in loamy or sandy soil. The NIs was the most effective in sandy soils.

Anhedonia Predicts Poorer Recovery among Youth with Selective Serotonin Reuptake Inhibitor Treatment-Resistant Depression

Science.gov (United States)

McMakin, Dana L.; Olino, Thomas M.; Porta, Giovanna; Dietz, Laura J.; Emslie, Graham; Clarke, Gregory; Wagner, Karen Dineen; Asarnow, Joan R.; Ryan, Neal D.; Birmaher, Boris; Shamseddeen, Wael; Mayes, Taryn; Kennard, Betsy; Spirito, Anthony; Keller, Martin; Lynch, Frances L.; Dickerson, John F.; Brent, David A.

2012-01-01

Objective: To identify symptom dimensions of depression that predict recovery among selective serotonin reuptake inhibitor (SSRI) treatment-resistant adolescents undergoing second-step treatment. Method: The Treatment of Resistant Depression in Adolescents (TORDIA) trial included 334 SSRI treatment-resistant youth randomized to a medication…

Molecular design and structure--activity relationships leading to the potent, selective, and orally active thrombin active site inhibitor BMS-189664.

Science.gov (United States)

Das, Jagabandhu; Kimball, S David; Hall, Steven E; Han, Wen Ching; Iwanowicz, Edwin; Lin, James; Moquin, Robert V; Reid, Joyce A; Sack, John S; Malley, Mary F; Chang, Chiehying Y; Chong, Saeho; Wang-Iverson, David B; Roberts, Daniel G M; Seiler, Steven M; Schumacher, William A; Ogletree, Martin L

2002-01-07

A series of structurally novel small molecule inhibitors of human alpha-thrombin was prepared to elucidate their structure-activity relationships (SARs), selectivity and activity in vivo. BMS-189664 (3) is identified as a potent, selective, and orally active reversible inhibitor of human alpha-thrombin which is efficacious in vivo in a mouse lethality model, and at inhibiting both arterial and venous thrombosis in cynomolgus monkey models.

Identification of STAT1 and STAT3 specific inhibitors using comparative virtual screening and docking validation.

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Malgorzata Szelag

Full Text Available Signal transducers and activators of transcription (STATs facilitate action of cytokines, growth factors and pathogens. STAT activation is mediated by a highly conserved SH2 domain, which interacts with phosphotyrosine motifs for specific STAT-receptor contacts and STAT dimerization. The active dimers induce gene transcription in the nucleus by binding to a specific DNA-response element in the promoter of target genes. Abnormal activation of STAT signaling pathways is implicated in many human diseases, like cancer, inflammation and auto-immunity. Searches for STAT-targeting compounds, exploring the phosphotyrosine (pTyr-SH2 interaction site, yielded many small molecules for STAT3 but sparsely for other STATs. However, many of these inhibitors seem not STAT3-specific, thereby questioning the present modeling and selection strategies of SH2 domain-based STAT inhibitors. We generated new 3D structure models for all human (hSTATs and developed a comparative in silico docking strategy to obtain further insight into STAT-SH2 cross-binding specificity of a selection of previously identified STAT3 inhibitors. Indeed, by primarily targeting the highly conserved pTyr-SH2 binding pocket the majority of these compounds exhibited similar binding affinity and tendency scores for all STATs. By comparative screening of a natural product library we provided initial proof for the possibility to identify STAT1 as well as STAT3-specific inhibitors, introducing the 'STAT-comparative binding affinity value' and 'ligand binding pose variation' as selection criteria. In silico screening of a multi-million clean leads (CL compound library for binding of all STATs, likewise identified potential specific inhibitors for STAT1 and STAT3 after docking validation. Based on comparative virtual screening and docking validation, we developed a novel STAT inhibitor screening tool that allows identification of specific STAT1 and STAT3 inhibitory compounds. This could increase our

Synthesis of the highly selective p38 MAPK inhibitor UR-13756 for possible therapeutic use in Werner syndrome.

Science.gov (United States)

Bagley, Mark C; Davis, Terence; Rokicki, Michal J; Widdowson, Caroline S; Kipling, David

2010-02-01

UR-13756 is a potent and selective p38 mitogen-activated protein kinase (MAPK) inhibitor, reported to have good bioavailability and pharmacokinetic properties and, thus, is of potential use in the treatment of accelerated aging in Werner syndrome. Irradiation of 2-chloroacrylonitrile and methylhydrazine in ethanol at 100 °C gives 1-methyl-3-aminopyrazole, which reacts with 4-fluorobenzaldehyde and a ketone, obtained by Claisen condensation of 4-picoline, in a Hantzsch-type 3-component hereocyclocondensation, to give the pyrazolopyridine UR-13756. UR-13756 shows p38 MAPK inhibitory activity in human telomerase reverse transcriptase-immortalized HCA2 dermal fibroblasts, with an IC(50) of 80 nm, as shown by ELISA, is 100% efficacious for up to 24 h at 1.0 μm and displays excellent kinase selectivity over the related stress-activated c-Jun kinases. In addition, UR-13756 is an effective p38 inhibitor at 1.0 μm in Werner syndrome cells, as shown by immunoblot. The convergent synthesis of UR-13756 is realized using microwave dielectric heating and provides a highly selective inhibitor that shows excellent selectivity for p38 MAPK over c-Jun N-terminal kinase.

Purification-Free, Target-Selective Immobilization of a Protein from Cell Lysates.

Science.gov (United States)

Cha, Jaehyun; Kwon, Inchan

2018-02-27

Protein immobilization has been widely used for laboratory experiments and industrial processes. Preparation of a recombinant protein for immobilization usually requires laborious and expensive purification steps. Here, a novel purification-free, target-selective immobilization technique of a protein from cell lysates is reported. Purification steps are skipped by immobilizing a target protein containing a clickable non-natural amino acid (p-azidophenylalanine) in cell lysates onto alkyne-functionalized solid supports via bioorthogonal azide-alkyne cycloaddition. In order to achieve a target protein-selective immobilization, p-azidophenylalanine was introduced into an exogenous target protein, but not into endogenous non-target proteins using host cells with amber codon-free genomic DNAs. Immobilization of superfolder fluorescent protein (sfGFP) from cell lysates is as efficient as that of the purified sfGFP. Using two fluorescent proteins (sfGFP and mCherry), the authors also demonstrated that the target proteins are immobilized with a minimal immobilization of non-target proteins (target-selective immobilization). © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ribonucleotide Reductase Inhibitors: A New Look at an Old Target for Radiosensitization

International Nuclear Information System (INIS)

Chapman, Tobias R.; Kinsella, Timothy J.

2012-01-01

Ribonucleotide reductase (RR), the rate limiting enzyme in the synthesis and repair of DNA, has been studied as a target for inhibition in the treatment of cancer for many years. While some researchers have focused on RR inhibitors as chemotherapeutic agents, particularly in hematologic malignancies, some of the most promising data has been generated in the field of radiosensitization. Early pre-clinical studies demonstrated that the addition of the first of these drugs, hydroxyurea, to ionizing radiation (IR) produced a synergistic effect in vitro, leading to a large number of clinical studies in the 1970–1980s. These studies, mainly in cervical cancer, initially produced a great deal of interest, leading to the incorporation of hydroxyurea in the treatment protocols of many institutions. However, over time, the conclusions from these studies have been called into question and hydroxyurea has been replaced in the standard of care of cervical cancer. Over the last 10 years, a number of well-done pre-clinical studies have greatly advanced our understanding of RR as a target. Those advances include the elucidation of the role of p53R2 and our understanding of the temporal relationship between the delivery of IR and the response of RR. At the same time, new inhibitors with increased potency and improved binding characteristics have been discovered, and pre-clinical and early clinical data look promising. Here we present a comprehensive review of the pre-clinical and clinical data in the field to date and provide some discussion of future areas of research.

Ribonucleotide Reductase Inhibitors: A New Look at an Old Target for Radiosensitization

Energy Technology Data Exchange (ETDEWEB)

Chapman, Tobias R. [Tufts University School of Medicine, Boston, MA (United States); Kinsella, Timothy J., E-mail: tkinsella@lifespan.org [Department of Radiation Oncology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, RI (United States)

2012-01-04

Ribonucleotide reductase (RR), the rate limiting enzyme in the synthesis and repair of DNA, has been studied as a target for inhibition in the treatment of cancer for many years. While some researchers have focused on RR inhibitors as chemotherapeutic agents, particularly in hematologic malignancies, some of the most promising data has been generated in the field of radiosensitization. Early pre-clinical studies demonstrated that the addition of the first of these drugs, hydroxyurea, to ionizing radiation (IR) produced a synergistic effect in vitro, leading to a large number of clinical studies in the 1970–1980s. These studies, mainly in cervical cancer, initially produced a great deal of interest, leading to the incorporation of hydroxyurea in the treatment protocols of many institutions. However, over time, the conclusions from these studies have been called into question and hydroxyurea has been replaced in the standard of care of cervical cancer. Over the last 10 years, a number of well-done pre-clinical studies have greatly advanced our understanding of RR as a target. Those advances include the elucidation of the role of p53R2 and our understanding of the temporal relationship between the delivery of IR and the response of RR. At the same time, new inhibitors with increased potency and improved binding characteristics have been discovered, and pre-clinical and early clinical data look promising. Here we present a comprehensive review of the pre-clinical and clinical data in the field to date and provide some discussion of future areas of research.

Targeting tumorigenesis: development and use of mTOR inhibitors in cancer therapy

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Kay Andrea

2009-10-01

Full Text Available Abstract The mammalian target of rapamycin (mTOR is an intracellular serine/threonine protein kinase positioned at a central point in a variety of cellular signaling cascades. The established involvement of mTOR activity in the cellular processes that contribute to the development and progression of cancer has identified mTOR as a major link in tumorigenesis. Consequently, inhibitors of mTOR, including temsirolimus, everolimus, and ridaforolimus (formerly deforolimus have been developed and assessed for their safety and efficacy in patients with cancer. Temsirolimus is an intravenously administered agent approved by the US Food and Drug Administration (FDA and the European Medicines Agency (EMEA for the treatment of advanced renal cell carcinoma (RCC. Everolimus is an oral agent that has recently obtained US FDA and EMEA approval for the treatment of advanced RCC after failure of treatment with sunitinib or sorafenib. Ridaforolimus is not yet approved for any indication. The use of mTOR inhibitors, either alone or in combination with other anticancer agents, has the potential to provide anticancer activity in numerous tumor types. Cancer types in which these agents are under evaluation include neuroendocrine tumors, breast cancer, leukemia, lymphoma, hepatocellular carcinoma, gastric cancer, pancreatic cancer, sarcoma, endometrial cancer, and non-small-cell lung cancer. The results of ongoing clinical trials with mTOR inhibitors, as single agents and in combination regimens, will better define their activity in cancer.

Survivin - an inhibitor of apoptosis and a new therapeutic target in cancer

International Nuclear Information System (INIS)

Pizem, J.; Coer, A.

2003-01-01

Survivin is a unique member of the inhibitor of apoptosis (IAP) protein family. It inhibits apoptosis by interfering with post-mitochondrial events during apoptosis, thus blocking activation of caspases. The expression of survivin is among the most tumour specific of all human genes. It is overexpressed in most human cancers but is not detected in most normal tissues. Some molecular mechanisms of survivin upregulation in cancer have been elucidated, including loss of the wild-type p53. Tumours that overexpress survivin generally bear a worse prognosis and are associated with resistance to therapy. Its differential expression in cancer versus normal tissues makes survivin detection a useful tool in cancer diagnostics and a promising therapeutic target. Survivin targeting has resulted in increased spontaneous and induced apoptosis and inhibition of tumour growth. Some anticancer drugs currently introduced into clinical practice might well act by inactivating survivin. (author)

Recent Advances in the Development and Application of Radiolabeled Kinase Inhibitors for PET Imaging

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Vadim Bernard-Gauthier

2015-12-01

Full Text Available Over the last 20 years, intensive investigation and multiple clinical successes targeting protein kinases, mostly for cancer treatment, have identified small molecule kinase inhibitors as a prominent therapeutic class. In the course of those investigations, radiolabeled kinase inhibitors for positron emission tomography (PET imaging have been synthesized and evaluated as diagnostic imaging probes for cancer characterization. Given that inhibitor coverage of the kinome is continuously expanding, in vivo PET imaging will likely find increasing applications for therapy monitoring and receptor density studies both in- and outside of oncological conditions. Early investigated radiolabeled inhibitors, which are mostly based on clinically approved tyrosine kinase inhibitor (TKI isotopologues, have now entered clinical trials. Novel radioligands for cancer and PET neuroimaging originating from novel but relevant target kinases are currently being explored in preclinical studies. This article reviews the literature involving radiotracer design, radiochemistry approaches, biological tracer evaluation and nuclear imaging results of radiolabeled kinase inhibitors for PET reported between 2010 and mid-2015. Aspects regarding the usefulness of pursuing selective vs. promiscuous inhibitor scaffolds and the inherent challenges associated with intracellular enzyme imaging will be discussed.

The Azaindole Framework in the Design of Kinase Inhibitors

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Jean-Yves Mérour

2014-11-01

Full Text Available This review article illustrates the growing use of azaindole derivatives as kinase inhibitors and their contribution to drug discovery and innovation. The different protein kinases which have served as targets and the known molecules which have emerged from medicinal chemistry and Fragment-Based Drug Discovery (FBDD programs are presented. The various synthetic routes used to access these compounds and the chemical pathways leading to their synthesis are also discussed. An analysis of their mode of binding based on X-ray crystallography data gives structural insights for the design of more potent and selective inhibitors.

Novel target configurations for selective ionization state studies in molybdenum

International Nuclear Information System (INIS)

Ilcisin, K.J.; Feldman, U.; Schwob, J.L.; Wouters, A.; Suckewer, S.; Princeton Univ., NJ

1990-03-01

Details of experiments aimed at achieving low ionization state selectivity in molybdenum are presented. Targets are excited with a 10 J CO 2 laser and the resultant VUV spectrum (300--700 Angstrom) has been studied. Combinations of focal spot size, target depth, and target geometries are compared. Simple attenuation of energy is shown not to vary ionization stage composition significantly. Experiments conducted with grazing incidence targets result only in a hot plasma. Modular targets with cooling cylinders of various radii demonstrated good selectivity of the ionization states, but with low absolute signals. Finally, results from combinations of focal spot adjustment and radiative cooling illustrate increased control over desired plasma temperature and density for spectroscopic studies of molybdenum. 7 refs., 14 figs

Discovering Small Molecule Inhibitors Targeted to Ligand-Stimulated RAGE-DIAPH1 Signaling Transduction

Science.gov (United States)

Pan, Jinhong

The receptor of advanced glycation end product (RAGE) is a multiligand receptor of the immunoglobulin superfamily of cell surface molecules, which plays an important role in immune responses. Full-length RAGE includes three extracellular immunoglobulin domains, a transmembrane domain and an intracellular domain. It is a pattern recognition receptor that can bind diverse ligands. NMR spectroscopy and x-ray crystallization studies of the extracellular domains of RAGE indicate that RAGE ligands bind by distinct charge- and hydrophobicity-dependent mechanisms. It is found that calgranulin binding to the C1C2 domain or AGEs binding to the V domain activates extracellular signaling, which triggers interactions of the RAGE cytoplasmic tail (ctRAGE) with intracellular effector, such as diaphanous 1 (DIAPH1), to initiate signal transduction cascades. ctRAGE is essential for RAGE-ligand-mediated signal transduction and consequent modulation of gene expression and cellular properties. RAGE is over-expressed in diseased tissues of most RAGE-associated pathogenic conditions, such as complications of Alzheimer's diseases, diabetes, vascular diseases, inflammation, cancers and neurodegeneration. They are the major diseases affecting a large population worldwide. RAGE can function as a biomarker or drug target for these diseases. The cytoplasmic tail of RAGE can be used as a drug target to inhibit RAGE-induced intracellular signaling by small molecule inhibitors to treat RAGE-associated diseases. We developed a high throughput screening assay with which we probed a small molecule library of 58,000 compounds to find that 777 small molecules displayed 50% inhibition and 97 compounds demonstrated dose-dependent inhibition of the binding of ctRAGE-DIAPH1. Eventually, there were 13 compounds which displayed dose-dependent inhibition of ctRAGE binding to DIAPH1 and direct binding to ctRAGE analyzed by 15N HSQC-NMR and native tryptophan fluorescence titration experiments; thus, they were

Nonstructural Proteins of Alphavirus—Potential Targets for Drug Development

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Farhana Abu Bakar

2018-02-01

Full Text Available Alphaviruses are enveloped, positive single-stranded RNA viruses, typically transmitted by arthropods. They often cause arthralgia or encephalitic diseases in infected humans and there is currently no targeted antiviral treatment available. The re-emergence of alphaviruses in Asia, Europe, and the Americas over the last decade, including chikungunya and o’nyong’nyong viruses, have intensified the search for selective inhibitors. In this review, we highlight key molecular determinants within the alphavirus replication complex that have been identified as viral targets, focusing on their structure and functionality in viral dissemination. We also summarize recent structural data of these viral targets and discuss how these could serve as templates to facilitate structure-based drug design and development of small molecule inhibitors.

Searching for Multi-Targeting Neurotherapeutics against Alzheimer’s: Discovery of Potent AChE-MAO B Inhibitors through the Decoration of the 2H-Chromen-2-one Structural Motif

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Leonardo Pisani

2016-03-01

Full Text Available The need for developing real disease-modifying drugs against neurodegenerative syndromes, particularly Alzheimer’s disease (AD, shifted research towards reliable drug discovery strategies to unveil clinical candidates with higher therapeutic efficacy than single-targeting drugs. By following the multi-target approach, we designed and synthesized a novel class of dual acetylcholinesterase (AChE-monoamine oxidase B (MAO-B inhibitors through the decoration of the 2H-chromen-2-one skeleton. Compounds bearing a propargylamine moiety at position 3 displayed the highest in vitro inhibitory activities against MAO-B. Within this series, derivative 3h emerged as the most interesting hit compound, being a moderate AChE inhibitor (IC50 = 8.99 µM and a potent and selective MAO-B inhibitor (IC50 = 2.8 nM. Preliminary studies in human neuroblastoma SH-SY5Y cell lines demonstrated its low cytotoxicity and disclosed a promising neuroprotective effect at low doses (0.1 µM under oxidative stress conditions promoted by two mitochondrial toxins (oligomycin-A and rotenone. In a Madin-Darby canine kidney (MDCKII-MDR1 cell-based transport study, Compound 3h was able to permeate the BBB-mimicking monolayer and did not result in a glycoprotein-p (P-gp substrate, showing an efflux ratio = 0.96, close to that of diazepam.

Novel Therapeutic Targets for Phosphodiesterase 5 Inhibitors: current state-of-the-art on systemic arterial hypertension and atherosclerosis.

Science.gov (United States)

Vasquez, Elisardo C; Gava, Agata L; Graceli, Jones B; Balarini, Camille M; Campagnaro, Bianca P; Pereira, Thiago Melo C; Meyrelles, Silvana S

2016-01-01

The usefulness of selective inhibitors of phosphodiesterase 5 (PDE5) is well known, first for the treatment of male erectile dysfunction and more recently for pulmonary hypertension. The discovery that PDE5 is present in the systemic artery endothelium and smooth muscle cells led investigators to test the extra sexual effects of sildenafil, the first and most investigated PDE5 inhibitor, in diseases affecting the systemic arteries. Cumulative data from experimental and clinical studies have revealed beneficial effects of sildenafil on systemic arterial hypertension and its target organs, such as the heart, kidneys and vasculature. An important effect of sildenafil is reduction of hypertension and improvement of endothelial function in experimental models of hypertension and hypertensive subjects. Interestingly, in angiotensin-dependent hypertension, its beneficial effects on endothelial and kidney dysfunctions seem to at least in part be caused by its ability to decrease the levels of angiotensin II and increase angiotensin 1-7, in addition to improving nitric oxide bioavailability and diminishing reactive oxygen species. Another remarkable finding on the effects of sildenafil comes from studies in apolipoprotein E knockout mice, a model of atherosclerosis that closely resembles human atherosclerotic disease. In this review, we focus on the promising beneficial effects of sildenafil for treating systemic high blood pressure, especially resistant hypertension, and the endothelial dysfunction that is present in hypertension and atherosclerosis.

Ticlopidine in Its Prodrug Form Is a Selective Inhibitor of Human NTPDase1

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Joanna Lecka

2014-01-01

Full Text Available Nucleoside triphosphate diphosphohydrolase-1 (NTPDase1, like other ectonucleotidases, controls extracellular nucleotide levels and consequently their (pathophysiological responses such as in thrombosis, inflammation, and cancer. Selective NTPDase1 inhibitors would therefore be very useful. We previously observed that ticlopidine in its prodrug form, which does not affect P2 receptor activity, inhibited the recombinant form of human NTPDase1 (Ki=14 μM. Here we tested whether ticlopidine can be used as a selective inhibitor of NTPDase1. We confirmed that ticlopidine inhibits NTPDase1 in different forms and in different assays. The ADPase activity of intact HUVEC as well as of COS-7 cells transfected with human NTPDase1 was strongly inhibited by 100 µM ticlopidine, 99 and 86%, respectively. Ticlopidine (100 µM completely inhibited the ATPase activity of NTPDase1 in situ as shown by enzyme histochemistry with human liver and pancreas sections. Ticlopidine also inhibited the activity of rat and mouse NTPDase1 and of potato apyrase. At 100 µM ticlopidine did not affect the activity of human NTPDase2, NTPDase3, and NTPDase8, nor of NPP1 and NPP3. Weak inhibition (10–20% of NTPDase3 and -8 was observed at 1 mM ticlopidine. These results show that ticlopidine is a specific inhibitor of NTPDase1 that can be used in enzymatic and histochemistry assays.

Targeting Epidermal Growth Factor Receptor-Related Signaling Pathways in Pancreatic Cancer.

Science.gov (United States)

Philip, Philip A; Lutz, Manfred P

2015-10-01

Pancreatic cancer is aggressive, chemoresistant, and characterized by complex and poorly understood molecular biology. The epidermal growth factor receptor (EGFR) pathway is frequently activated in pancreatic cancer; therefore, it is a rational target for new treatments. However, the EGFR tyrosine kinase inhibitor erlotinib is currently the only targeted therapy to demonstrate a very modest survival benefit when added to gemcitabine in the treatment of patients with advanced pancreatic cancer. There is no molecular biomarker to predict the outcome of erlotinib treatment, although rash may be predictive of improved survival; EGFR expression does not predict the biologic activity of anti-EGFR drugs in pancreatic cancer, and no EGFR mutations are identified as enabling the selection of patients likely to benefit from treatment. Here, we review clinical studies of EGFR-targeted therapies in combination with conventional cytotoxic regimens or multitargeted strategies in advanced pancreatic cancer, as well as research directed at molecules downstream of EGFR as alternatives or adjuncts to receptor targeting. Limitations of preclinical models, patient selection, and trial design, as well as the complex mechanisms underlying resistance to EGFR-targeted agents, are discussed. Future clinical trials must incorporate translational research end points to aid patient selection and circumvent resistance to EGFR inhibitors.

A new O6-alkylguanine-DNA alkyltransferase inhibitor associated with a nitrosourea (cystemustine) validates a strategy of melanoma-targeted therapy in murine B16 and human-resistant M4Beu melanoma xenograft models.

Science.gov (United States)

Rapp, Maryse; Maurizis, Jean C; Papon, Janine; Labarre, Pierre; Wu, Ting-Di; Croisy, Alain; Guerquin-Kern, Jean L; Madelmont, Jean C; Mounetou, Emmanuelle

2008-07-01

Chemoresistance to O(6)-alkylating agents is a major barrier to successful treatment of melanoma. It is mainly due to a DNA repair suicide protein, O(6)-alkylguanine-DNA alkyltransferase (AGT). Although AGT inactivation is a powerful clinical strategy for restoring tumor chemosensitivity, it was limited by increased toxicity to nontumoral cells resulting from a lack of tumor selectivity. Achieving enhanced chemosensitization via AGT inhibition preferably in the tumor should protect normal tissue. To this end, we have developed a strategy to target AGT inhibitors. In this study, we tested a new potential melanoma-directed AGT inhibitor [2-amino-6-(4-iodobenzyloxy)-9-[4-(diethylamino) ethylcarbamoylbenzyl] purine; IBgBZ] designed as a conjugate of O(6)-(4-iododbenzyl)guanine (IBg) as the AGT inactivator and a N,N-diethylaminoethylenebenzamido (BZ) moiety as the carrier to the malignant melanocytes. IBgBZ demonstrated AGT inactivation ability and potentiation of O(6)-alkylating agents (cystemustine, a chloroethylnitrosourea) in M4Beu highly chemoresistant human melanoma cells both in vitro and in tumor models. The biodisposition study on mice bearing B16 melanoma, the standard model for the evaluation of melanoma-directed agents, and the secondary ion mass spectrometry imaging confirmed the concentration of IBgBZ in the tumor and in particular in the intracytoplasmic melanosomes. These results validate the potential of IBgBZ as a new, more tumor-selective, AGT inhibitor in a strategy of melanoma-targeted therapy.

Biochemical analysis of leishmanial and human GDP-Mannose Pyrophosphorylases and selection of inhibitors as new leads.

Science.gov (United States)

Mao, Wei; Daligaux, Pierre; Lazar, Noureddine; Ha-Duong, Tâp; Cavé, Christian; van Tilbeurgh, Herman; Loiseau, Philippe M; Pomel, Sébastien

2017-04-07

Leishmaniases are an ensemble of diseases caused by the protozoan parasite of the genus Leishmania. Current antileishmanial treatments are limited and present main issues of toxicity and drug resistance emergence. Therefore, the generation of new inhibitors specifically directed against a leishmanial target is an attractive strategy to expand the chemotherapeutic arsenal. GDP-Mannose Pyrophosphorylase (GDP-MP) is a prominent therapeutic target involved in host-parasite recognition which has been described to be essential for parasite survival. In this work, we produced and purified GDP-MPs from L. mexicana (LmGDP-MP), L. donovani (LdGDP-MP), and human (hGDP-MP), and compared their enzymatic properties. From a rationale design of 100 potential inhibitors, four compounds were identified having a promising and specific inhibitory effect on parasite GDP-MP and antileishmanial activities, one of them exhibits a competitive inhibition on LdGDP-MP and belongs to the 2-substituted quinoline series.

A new screening method to identify inhibitors of the Lol (localization of lipoproteins) system, a novel antibacterial target.

Science.gov (United States)

Ito, Hideaki; Ura, Atsushi; Oyamada, Yoshihiro; Yoshida, Hiroaki; Yamagishi, Jun-Ichi; Narita, Shin-Ichiro; Matsuyama, Shin-Ichi; Tokuda, Hajime

2007-01-01

As the Lol system, which is involved in localization of lipoproteins, is essential for Escherichia coli growth and widely conserved among gram-negative bacteria, it is considered to be a promising target for the development of anti-gram-negative bacterial agents. However, no high-throughput screening method has so far been developed to screen for Lol system inhibitors. By combining three assay systems (anucleate cell blue assay, Lpp assay, and LolA-dependent release inhibition assay) and a drug susceptibility test, we have successfully developed a new screening method for identification of compounds that inhibit the Lol system. Using this new screening method, we screened 23,600 in-house chemical compounds and found 2 Lol system inhibitors. We therefore conclude that our new screening method can efficiently identify new antibacterial agents that target the Lol system.

In Utero Exposure to Selective Serotonin Reuptake Inhibitors and Risk for Autism Spectrum Disorder

Science.gov (United States)

Gidaya, Nicole B.; Lee, Brian K.; Burstyn, Igor; Yudell, Michael; Mortensen, Erik L.; Newschaffer, Craig J.

2014-01-01

We investigated whether there is an association between increased risk for autism spectrum disorders (ASD) and selective serotonin reuptake inhibitors (SSRIs) used during pregnancy. This study used Denmark's health and population registers to obtain information regarding prescription drugs, ASD diagnosis, and health and socioeconomic status. There…

Identification of Early Intermediates of Caspase Activation Using Selective Inhibitors and Activity-Based Probes

NARCIS (Netherlands)

Berger, Alicia B.; Witte, Martin D.; Denault, Jean-Bernard; Sadaghiani, Amir Masoud; Sexton, Kelly M.B.; Salvesen, Guy S.; Bogyo, Matthew

2006-01-01

Caspases are cysteine proteases that are key effectors in apoptotic cell death. Currently, there is a lack of tools that can be used to monitor the regulation of specific caspases in the context of distinct apoptotic programs. We describe the development of highly selective inhibitors and active

1,3-Oxazole-based selective picomolar inhibitors of cytosolic human carbonic anhydrase II alleviate ocular hypertension in rabbits: Potency is supported by X-ray crystallography of two leads.

Science.gov (United States)

Ferraroni, Marta; Lucarini, Laura; Masini, Emanuela; Korsakov, Mikhail; Scozzafava, Andrea; Supuran, Claudiu T; Krasavin, Mikhail

2017-09-01

Two lead 1,3-oxazole-based carbonic anhydrase inhibitors (CAIs) earlier identified as selective, picomolar inhibitors of hCA II (a cytosolic target for treatment of glaucoma) have been investigated further. Firstly, they were found to be conveniently synthesized on multigram scale, which enables further development. These compounds were found to be comparable in efficacy to dorzolamide eye drops when applied in the eye drop form as well. Finally, the reasons for unusually high potency of these compounds became understood from their high-resolution X-ray crystallography structures. These data significantly expand our understanding of heterocycle-based primary sulfonamides, many of which have recently emerged from our labs - particularly, from the corneal permeability standpoint. Copyright © 2017 Elsevier Ltd. All rights reserved.

Non-peptidic cruzain inhibitors with trypanocidal activity discovered by virtual screening and in vitro assay.

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Helton J Wiggers

Full Text Available A multi-step cascade strategy using integrated ligand- and target-based virtual screening methods was developed to select a small number of compounds from the ZINC database to be evaluated for trypanocidal activity. Winnowing the database to 23 selected compounds, 12 non-covalent binding cruzain inhibitors with affinity values (K i in the low micromolar range (3-60 µM acting through a competitive inhibition mechanism were identified. This mechanism has been confirmed by determining the binding mode of the cruzain inhibitor Nequimed176 through X-ray crystallographic studies. Cruzain, a validated therapeutic target for new chemotherapy for Chagas disease, also shares high similarity with the mammalian homolog cathepsin L. Because increased activity of cathepsin L is related to invasive properties and has been linked to metastatic cancer cells, cruzain inhibitors from the same library were assayed against it. Affinity values were in a similar range (4-80 µM, yielding poor selectivity towards cruzain but raising the possibility of investigating such inhibitors for their effect on cell proliferation. In order to select the most promising enzyme inhibitors retaining trypanocidal activity for structure-activity relationship (SAR studies, the most potent cruzain inhibitors were assayed against T. cruzi-infected cells. Two compounds were found to have trypanocidal activity. Using compound Nequimed42 as precursor, an SAR was established in which the 2-acetamidothiophene-3-carboxamide group was identified as essential for enzyme and parasite inhibition activities. The IC50 value for compound Nequimed42 acting against the trypomastigote form of the Tulahuen lacZ strain was found to be 10.6±0.1 µM, tenfold lower than that obtained for benznidazole, which was taken as positive control. In addition, by employing the strategy of molecular simplification, a smaller compound derived from Nequimed42 with a ligand efficiency (LE of 0.33 kcal mol(-1 atom(-1

Non-peptidic cruzain inhibitors with trypanocidal activity discovered by virtual screening and in vitro assay.

Science.gov (United States)

Wiggers, Helton J; Rocha, Josmar R; Fernandes, William B; Sesti-Costa, Renata; Carneiro, Zumira A; Cheleski, Juliana; da Silva, Albérico B F; Juliano, Luiz; Cezari, Maria H S; Silva, João S; McKerrow, James H; Montanari, Carlos A

2013-01-01

A multi-step cascade strategy using integrated ligand- and target-based virtual screening methods was developed to select a small number of compounds from the ZINC database to be evaluated for trypanocidal activity. Winnowing the database to 23 selected compounds, 12 non-covalent binding cruzain inhibitors with affinity values (K i) in the low micromolar range (3-60 µM) acting through a competitive inhibition mechanism were identified. This mechanism has been confirmed by determining the binding mode of the cruzain inhibitor Nequimed176 through X-ray crystallographic studies. Cruzain, a validated therapeutic target for new chemotherapy for Chagas disease, also shares high similarity with the mammalian homolog cathepsin L. Because increased activity of cathepsin L is related to invasive properties and has been linked to metastatic cancer cells, cruzain inhibitors from the same library were assayed against it. Affinity values were in a similar range (4-80 µM), yielding poor selectivity towards cruzain but raising the possibility of investigating such inhibitors for their effect on cell proliferation. In order to select the most promising enzyme inhibitors retaining trypanocidal activity for structure-activity relationship (SAR) studies, the most potent cruzain inhibitors were assayed against T. cruzi-infected cells. Two compounds were found to have trypanocidal activity. Using compound Nequimed42 as precursor, an SAR was established in which the 2-acetamidothiophene-3-carboxamide group was identified as essential for enzyme and parasite inhibition activities. The IC50 value for compound Nequimed42 acting against the trypomastigote form of the Tulahuen lacZ strain was found to be 10.6±0.1 µM, tenfold lower than that obtained for benznidazole, which was taken as positive control. In addition, by employing the strategy of molecular simplification, a smaller compound derived from Nequimed42 with a ligand efficiency (LE) of 0.33 kcal mol(-1) atom(-1) (compound

Systematic Kinase Inhibitor Profiling Identifies CDK9 as a Synthetic Lethal Target in NUT Midline Carcinoma

Directory of Open Access Journals (Sweden)

Johannes Brägelmann

2017-09-01

Full Text Available Kinase inhibitors represent the backbone of targeted cancer therapy, yet only a limited number of oncogenic drivers are directly druggable. By interrogating the activity of 1,505 kinase inhibitors, we found that BRD4-NUT-rearranged NUT midline carcinoma (NMC cells are specifically killed by CDK9 inhibition (CDK9i and depend on CDK9 and Cyclin-T1 expression. We show that CDK9i leads to robust induction of apoptosis and of markers of DNA damage response in NMC cells. While both CDK9i and bromodomain inhibition over time result in reduced Myc protein expression, only bromodomain inhibition induces cell differentiation and a p21-induced cell-cycle arrest in these cells. Finally, RNA-seq and ChIP-based analyses reveal a BRD4-NUT-specific CDK9i-induced perturbation of transcriptional elongation. Thus, our data provide a mechanistic basis for the genotype-dependent vulnerability of NMC cells to CDK9i that may be of relevance for the development of targeted therapies for NMC patients.

JAK2 inhibitor therapy in myeloproliferative disorders: rationale, preclinical studies and ongoing clinical trials.

Science.gov (United States)

Pardanani, A

2008-01-01

The recent identification of somatic mutations such as JAK2V617F that deregulate Janus kinase (JAK)-signal transducer and activator of transcription signaling has spurred development of orally bioavailable small-molecule inhibitors that selectively target JAK2 kinase as an approach to pathogenesis-directed therapy of myeloproliferative disorders (MPD). In pre-clinical studies, these compounds inhibit JAK2V617F-mediated cell growth at nanomolar concentrations, and in vivo therapeutic efficacy has been demonstrated in mouse models of JAK2V617F-induced disease. In addition, ex vivo growth of progenitor cells from MPD patients harboring JAK2V617F or MPLW515L/K mutations is also potently inhibited. JAK2 inhibitors currently in clinical trials can be grouped into those designed to primarily target JAK2 kinase (JAK2-selective) and those originally developed for non-MPD indications, but that nevertheless have significant JAK2-inhibitory activity (non-JAK2 selective). This article discusses the rationale for using JAK2 inhibitors for the treatment of MPD, as well as relevant aspects of clinical trial development for these patients. For instance, which group of MPD patients is appropriate for initial Phase I studies? Should JAK2V617F-negative MPD patients be included in the initial studies? What are the likely consequences of 'off-target' JAK3 and wild-type JAK2 inhibition? How should treatment responses be monitored?

Selection of phage-displayed accessible recombinant targeted antibodies (SPARTA): methodology and applications.

Science.gov (United States)

D'Angelo, Sara; Staquicini, Fernanda I; Ferrara, Fortunato; Staquicini, Daniela I; Sharma, Geetanjali; Tarleton, Christy A; Nguyen, Huynh; Naranjo, Leslie A; Sidman, Richard L; Arap, Wadih; Bradbury, Andrew Rm; Pasqualini, Renata

2018-05-03

We developed a potentially novel and robust antibody discovery methodology, termed selection of phage-displayed accessible recombinant targeted antibodies (SPARTA). This combines an in vitro screening step of a naive human antibody library against known tumor targets, with in vivo selections based on tumor-homing capabilities of a preenriched antibody pool. This unique approach overcomes several rate-limiting challenges to generate human antibodies amenable to rapid translation into medical applications. As a proof of concept, we evaluated SPARTA on 2 well-established tumor cell surface targets, EphA5 and GRP78. We evaluated antibodies that showed tumor-targeting selectivity as a representative panel of antibody-drug conjugates (ADCs) and were highly efficacious. Our results validate a discovery platform to identify and validate monoclonal antibodies with favorable tumor-targeting attributes. This approach may also extend to other diseases with known cell surface targets and affected tissues easily isolated for in vivo selection.

In silico design and biological evaluation of a dual specificity kinase inhibitor targeting cell cycle progression and angiogenesis.

Directory of Open Access Journals (Sweden)

Antony M Latham

Full Text Available Protein kinases play a central role in tumor progression, regulating fundamental processes such as angiogenesis, proliferation and metastasis. Such enzymes are an increasingly important class of drug target with small molecule kinase inhibitors being a major focus in drug development. However, balancing drug specificity and efficacy is problematic with off-target effects and toxicity issues.We have utilized a rational in silico-based approach to demonstrate the design and study of a novel compound that acts as a dual inhibitor of vascular endothelial growth factor receptor 2 (VEGFR2 and cyclin-dependent kinase 1 (CDK1. This compound acts by simultaneously inhibiting pro-angiogenic signal transduction and cell cycle progression in primary endothelial cells. JK-31 displays potent in vitro activity against recombinant VEGFR2 and CDK1/cyclin B proteins comparable to previously characterized inhibitors. Dual inhibition of the vascular endothelial growth factor A (VEGF-A-mediated signaling response and CDK1-mediated mitotic entry elicits anti-angiogenic activity both in an endothelial-fibroblast co-culture model and a murine ex vivo model of angiogenesis.We deduce that JK-31 reduces the growth of both human endothelial cells and human breast cancer cells in vitro. This novel synthetic molecule has broad implications for development of similar multi-kinase inhibitors with anti-angiogenic and anti-cancer properties. In silico design is an attractive and innovative method to aid such drug discovery.

A comparative study of fuzzy target selection methods in direct marketing

NARCIS (Netherlands)

Costa Sousa, da J.M.; Kaymak, U.; Madeira, S.

2002-01-01

Target selection in direct marketing is an important data mining problem for which fuzzy modeling can be used. The paper compares several fuzzy modeling techniques applied to target selection based on recency, frequency and monetary value measures. The comparison uses cross validation applied to

Are Selective Serotonin Reuptake Inhibitors Safe for Drivers? What is the Evidence?

OpenAIRE

Ravera, Silvia; Ramaekers, Johannes G.; de Jong-van den Berg, Lolkje T. W.; de Gier, Johan J.; de Jong-van den Berg, [No Value

2012-01-01

Background: Selective serotonin reuptake inhibitors (SSRIs) are widely used medications to treat several psychiatric diseases and, above all, depression. They seem to be as effective as older antidepressants but have a different adverse effect profile. Despite their favorable safety profile, little is known about their influence on traffic safety. Objective: To conduct a literature review to summarize the current evidence on the role of SSRIs in traffic safety, particularly concerning undesir...

PI3K inhibitors as new cancer therapeutics: implications for clinical trial design

Directory of Open Access Journals (Sweden)

Massacesi C

2016-01-01

Full Text Available Cristian Massacesi,1 Emmanuelle Di Tomaso,2 Patrick Urban,3 Caroline Germa,4 Cornelia Quadt,5 Lucia Trandafir,1 Paola Aimone,3 Nathalie Fretault,1 Bharani Dharan,4 Ranjana Tavorath,4 Samit Hirawat4 1Novartis Oncology, Paris, France; 2Novartis Institutes for BioMedical Research Inc, Cambridge, MA, USA; 3Novartis Pharma AG, Basel, Switzerland; 4Novartis Pharmaceuticals Corporation, East Hanover, NJ, USA; 5Novartis Pharmaceuticals KK, Tokyo, Japan Abstract: The PI3K–AKT–mTOR pathway is frequently activated in cancer. PI3K inhibitors, including the pan-PI3K inhibitor buparlisib (BKM120 and the PI3Kα-selective inhibitor alpelisib (BYL719, currently in clinical development by Novartis Oncology, may therefore be effective as anticancer agents. Early clinical studies with PI3K inhibitors have demonstrated preliminary antitumor activity and acceptable safety profiles. However, a number of unanswered questions regarding PI3K inhibition in cancer remain, including: what is the best approach for different tumor types, and which biomarkers will accurately identify the patient populations most likely to benefit from specific PI3K inhibitors? This review summarizes the strategies being employed by Novartis Oncology to help maximize the benefits of clinical studies with buparlisib and alpelisib, including stratification according to PI3K pathway activation status, selective enrollment/target enrichment (where patients with PI3K pathway-activated tumors are specifically recruited, nonselective enrollment with mandatory tissue collection, and enrollment of patients who have progressed on previous targeted agents, such as mTOR inhibitors or endocrine therapy. An overview of Novartis-sponsored and Novartis-supported trials that are utilizing these approaches in a range of cancer types, including breast cancer, head and neck squamous cell carcinoma, non-small cell lung carcinoma, lymphoma, and glioblastoma multiforme, is also described. Keywords: PI3K�

Improved Potency of Indole-Based NorA Efflux Pump Inhibitors: From Serendipity toward Rational Design and Development.

Science.gov (United States)

Buonerba, Federica; Lepri, Susan; Goracci, Laura; Schindler, Bryan D; Seo, Susan M; Kaatz, Glenn W; Cruciani, Gabriele

2017-01-12

The NorA efflux pump is a potential drug target for reversal of resistance to selected antibacterial agents, and recently we described indole-based inhibitor candidates. Herein we report a second class of inhibitors derived from them but with significant differences in shape and size. In particular, compounds 13 and 14 are very potent inhibitors in that they demonstrated the lowest IC 50 values (2 μM) ever observed among all indole-based compounds we have evaluated.

Design of Highly Potent Urea-Based, Exosite-Binding Inhibitors Selective for Glutamate Carboxypeptidase II

Czech Academy of Sciences Publication Activity Database

Tykvart, Jan; Schimer, Jiří; Jančařík, Andrej; Bařinková, Jitka; Navrátil, Václav; Starková, Jana; Šrámková, Karolína; Konvalinka, Jan; Majer, Pavel; Šácha, Pavel

2015-01-01

Roč. 58, č. 10 (2015), s. 4357-4363 ISSN 0022-2623 R&D Projects: GA ČR GBP208/12/G016; GA MŠk LO1302 Institutional support: RVO:61388963 Keywords : GCPII selective inhibitors * GCPIII * GCPII Subject RIV: CE - Biochemistry Impact factor: 5.589, year: 2015

Improved targeted immunization strategies based on two rounds of selection

Science.gov (United States)

Xia, Ling-Ling; Song, Yu-Rong; Li, Chan-Chan; Jiang, Guo-Ping

2018-04-01

In the case of high degree targeted immunization where the number of vaccine is limited, when more than one node associated with the same degree meets the requirement of high degree centrality, how can we choose a certain number of nodes from those nodes, so that the number of immunized nodes will not exceed the limit? In this paper, we introduce a new idea derived from the selection process of second-round exam to solve this problem and then propose three improved targeted immunization strategies. In these proposed strategies, the immunized nodes are selected through two rounds of selection, where we increase the quotas of first-round selection according the evaluation criterion of degree centrality and then consider another characteristic parameter of node, such as node's clustering coefficient, betweenness and closeness, to help choose targeted nodes in the second-round selection. To validate the effectiveness of the proposed strategies, we compare them with the degree immunizations including the high degree targeted and the high degree adaptive immunizations using two metrics: the size of the largest connected component of immunized network and the number of infected nodes. Simulation results demonstrate that the proposed strategies based on two rounds of sorting are effective for heterogeneous networks and their immunization effects are better than that of the degree immunizations.

HER2-targeted therapy in breast cancer. Monoclonal antibodies and tyrosine kinase inhibitors

DEFF Research Database (Denmark)

Nielsen, Dorte Lisbet; Andersson, Michael; Kamby, Claus

2008-01-01

There is strong clinical evidence that trastuzumab, a monoclonal antibody targeting the human epidermal growth factor receptor (HER) two tyrosine kinase receptor, is an important component of first-line treatment of patients with HER2-positive metastatic breast cancer. In particular the combination...... of trastuzumab to chemotherapy improves disease-free and overall survival. The use of lapatinib, a dual tyrosine kinase inhibitor of both HER1 and HER2, in combination with capecitabine in the second-line treatment of HER2-positive patients with metastatic breast cancer previously treated with trastuzumab has...

Celecoxib versus a non-selective NSAID plus proton-pump inhibitor: what are the considerations?.

Science.gov (United States)

Chen, Judy T; Pucino, Frank; Resman-Targoff, Beth H

2006-01-01

Nonsteroidal anti-inflammatory drugs (NSAIDs) are extensively used worldwide. However, associated adverse gastrointestinal effects (NSAID gastropathy) such as bleeding, perforation and obstruction result in considerable morbidity, mortality, and expense. Although it is essential to employ gastroprotective strategies to minimize these complications in patients at risk, controversy remains on whether celecoxib alone or a non-selective NSAID in conjunction with a proton-pump inhibitor (PPI) is a superior choice. Recent concerns regarding potential cardiovascular toxicities associated with cox-2 selective inhibitors may favor non-selective NSAID/PPI co-therapy as the preferred choice. Concomitant use of low-dose aspirin with any NSAID increases the risk of gastrointestinal complications and diminishes the improved gastrointestinal safety profile of celecoxib; whereas use of ibuprofen plus PPI regimens may negate aspirin's antiplatelet benefits. Evidence shows that concurrent use of a non-selective NSAID (such as naproxen) plus a PPI is as effective in preventing NSAID gastropathy as celecoxib, and may be more cost-effective. Patients failing or intolerant to this therapy would be candidates for celecoxib at the lowest effective dose for the shortest duration of time. Potential benefits from using low-dose celecoxib with a PPI in patients previously experiencing bleeding ulcers while taking NSAIDs remains to be proven. An evidence-based debate is presented to assist clinicians with the difficult decision-making process of preventing NSAID gastropathy while minimizing other complications.

Kinetic modelling of in vitro data of PI3K, mTOR1, PTEN enzymes and on-target inhibitors Rapamycin, BEZ235, and LY294002.

Science.gov (United States)

Goltsov, Alexey; Tashkandi, Ghassan; Langdon, Simon P; Harrison, David J; Bown, James L

2017-01-15

The phosphatidylinositide 3-kinases (PI3K) and mammalian target of rapamycin-1 (mTOR1) are two key targets for anti-cancer therapy. Predicting the response of the PI3K/AKT/mTOR1 signalling pathway to targeted therapy is made difficult because of network complexities. Systems biology models can help explore those complexities but the value of such models is dependent on accurate parameterisation. Motivated by a need to increase accuracy in kinetic parameter estimation, and therefore the predictive power of the model, we present a framework to integrate kinetic data from enzyme assays into a unified enzyme kinetic model. We present exemplar kinetic models of PI3K and mTOR1, calibrated on in vitro enzyme data and founded on Michaelis-Menten (MM) approximation. We describe the effects of an allosteric mTOR1 inhibitor (Rapamycin) and ATP-competitive inhibitors (BEZ235 and LY294002) that show dual inhibition of mTOR1 and PI3K. We also model the kinetics of phosphatase and tensin homolog (PTEN), which modulates sensitivity of the PI3K/AKT/mTOR1 pathway to these drugs. Model validation with independent data sets allows investigation of enzyme function and drug dose dependencies in a wide range of experimental conditions. Modelling of the mTOR1 kinetics showed that Rapamycin has an IC 50 independent of ATP concentration and that it is a selective inhibitor of mTOR1 substrates S6K1 and 4EBP1: it retains 40% of mTOR1 activity relative to 4EBP1 phosphorylation and inhibits completely S6K1 activity. For the dual ATP-competitive inhibitors of mTOR1 and PI3K, LY294002 and BEZ235, we derived the dependence of the IC 50 on ATP concentration that allows prediction of the IC 50 at different ATP concentrations in enzyme and cellular assays. Comparison of drug effectiveness in enzyme and cellular assays showed that some features of these drugs arise from signalling modulation beyond the on-target action and MM approximation and require a systems-level consideration of the whole PI3K

The age-dependent effects of selective serotonin reuptake inhibitors in humans and rodents: A review.

NARCIS (Netherlands)

Olivier, J.D.A.; Blom, T.; Arentsen, T.; Homberg, J.R.

2011-01-01

The selective serotonin reuptake inhibitor (SSRI) Prozac(R) (fluoxetine) is widely prescribed for the treatment of depression and anxiety-related disorders. While extensive research has established that fluoxetine is safe for adults, safety is not guaranteed for (unborn) children and adolescents.

Structure of matrix metalloproteinase-3 with a platinum-based inhibitor.

Science.gov (United States)

Belviso, Benny Danilo; Caliandro, Rocco; Siliqi, Dritan; Calderone, Vito; Arnesano, Fabio; Natile, Giovanni

2013-06-18

An X-ray investigation has been performed with the aim of characterizing the binding sites of a platinum-based inhibitor (K[PtCl3(DMSO)]) of matrix metalloproteinase-3 (stromelysin-1). The platinum complex targets His224 in the S1' specificity loop, representing the first step in the selective inhibition process (PDB ID code 4JA1).

Rational combination treatment with histone deacetylase inhibitors and immunomodulatory drugs in multiple myeloma

International Nuclear Information System (INIS)

Hideshima, T; Cottini, F; Ohguchi, H; Jakubikova, J; Gorgun, G; Mimura, N; Tai, Y-T; Munshi, N C; Richardson, P G; Anderson, K C

2015-01-01

Immunomodulatory drugs (IMiDs) thalidomide, lenalidomide (Len) and pomalidomide trigger anti-tumor activities in multiple myeloma (MM) by targetting cereblon and thereby impacting IZF1/3, c-Myc and IRF4. Histone deacetylase inhibitors (HDACi) also downregulate c-Myc. We therefore determined whether IMiDs with HDACi trigger significant MM cell growth inhibition by inhibiting or downregulating c-Myc. Combination treatment of Len with non-selective HDACi suberoylanilide hydroxamic acid or class-I HDAC-selective inhibitor MS275 induces synergic cytotoxicity, associated with downregulation of c-Myc. Unexpectedly, we observed that decreased levels of cereblon (CRBN), a primary target protein of IMiDs, was triggered by these agents. Indeed, sequential treatment of MM cells with MS275 followed by Len shows less efficacy than simultaneous treatment with this combination. Importantly ACY1215, an HDAC6 inhibitor with minimal effects on class-I HDACs, together with Len induces synergistic MM cytotoxicity without alteration of CRBN expression. Our results showed that only modest class-I HDAC inhibition is able to induce synergistic MM cytotoxicity in combination with Len. These studies may provide the framework for utilizing HDACi in combination with Len to both avoid CRBN downregulation and enhance anti-MM activities

Rational combination treatment with histone deacetylase inhibitors and immunomodulatory drugs in multiple myeloma.

Science.gov (United States)

Hideshima, T; Cottini, F; Ohguchi, H; Jakubikova, J; Gorgun, G; Mimura, N; Tai, Y-T; Munshi, N C; Richardson, P G; Anderson, K C

2015-05-15

Immunomodulatory drugs (IMiDs) thalidomide, lenalidomide (Len) and pomalidomide trigger anti-tumor activities in multiple myeloma (MM) by targetting cereblon and thereby impacting IZF1/3, c-Myc and IRF4. Histone deacetylase inhibitors (HDACi) also downregulate c-Myc. We therefore determined whether IMiDs with HDACi trigger significant MM cell growth inhibition by inhibiting or downregulating c-Myc. Combination treatment of Len with non-selective HDACi suberoylanilide hydroxamic acid or class-I HDAC-selective inhibitor MS275 induces synergic cytotoxicity, associated with downregulation of c-Myc. Unexpectedly, we observed that decreased levels of cereblon (CRBN), a primary target protein of IMiDs, was triggered by these agents. Indeed, sequential treatment of MM cells with MS275 followed by Len shows less efficacy than simultaneous treatment with this combination. Importantly ACY1215, an HDAC6 inhibitor with minimal effects on class-I HDACs, together with Len induces synergistic MM cytotoxicity without alteration of CRBN expression. Our results showed that only modest class-I HDAC inhibition is able to induce synergistic MM cytotoxicity in combination with Len. These studies may provide the framework for utilizing HDACi in combination with Len to both avoid CRBN downregulation and enhance anti-MM activities.

Burglar Target Selection: A Cross-National Comparison

NARCIS (Netherlands)

Townsley, M.; Birks, D.; Bernasco, W.; Johnson, S.D.; Ruiter, S.; White, G.

2015-01-01

Objectives: This study builds on research undertaken by Bernasco and Nieuwbeerta and explores the generalizability of a theoretically derived offender target selection model in three cross-national study regions. Methods: Taking a discrete spatial choice approach, we estimate the impact of both

Burglar Target Selection : A Cross-national Comparison

NARCIS (Netherlands)

Townsley, Michael; Birks, Daniel; Bernasco, Wim; Ruiter, Stijn; Johnson, Shane D.; White, Gentry; Baum, Scott

Objectives: This study builds on research undertaken by Bernasco and Nieuwbeerta and explores the generalizability of a theoretically derived offender target selection model in three cross-national study regions. Methods: Taking a discrete spatial choice approach, we estimate the impact of both

Risk evaluation and mitigation strategies: a focus on the mammalian target of rapamycin inhibitors.

Science.gov (United States)

Gabardi, Steven

2013-03-01

To review the history of risk evaluation and mitigation strategies (REMS) with the mammalian target of rapamycin (mToR) inhibitors, evaluate their required REMS elements, and delineate the reasons for them being released from their REMS requirements. Articles were identified through a literature search of MEDLINE and EMBASE (January 2007-July 2012) using the search terms: risk evaluation and mitigation strategies, REMS, everolimus, sirolimus and organ transplant (individual organs also were searched). Information from the Federal Register, the Food and Drug Administration, and the manufacturers of the mToR inhibitors was also evaluated. REMS are strategies implemented to manage known or potential risks associated with medications and to ensure ongoing pharmacovigilance throughout the life of a pharmaceutical product. The mToR inhibitors have been associated with several potential risks, including proteinuria, graft thrombosis, and wound-healing complications. The Food and Drug Administration approved REMS programs for both sirolimus and everolimus. The manufacturers of both medications complied with the components of their approved REMS, but after less than 2 years, both medications have been relieved of their REMS obligations. The only element of the sirolimus REMS was a medication guide, whereas the everolimus REMS consisted of a medication guide and a communication plan. The sirolimus REMS was implemented more than 10 years after its initial approval by the Food and Drug Administration, but was released from its REMS requirement within 7 months of its implementation. The everolimus REMS was instituted upon initial approval and was removed approximately 2 years later. Both medications' REMS were always intended to educate health care providers and patients about the potential risks associated with this transplant immunosuppressant. Transplant practitioners should be familiar with the mToR inhibitors' associated risks and properly educate patients regarding the

Magnetic Microbead Affinity Selection Screening (MagMass) of Botanical Extracts for Inhibitors of 15-Lipoxygenase

Science.gov (United States)

Rush, Michael D.; Walker, Elisabeth M.; Burton, Tristesse; van Breemen, Richard B.

2016-01-01

To expedite the identification of active natural products in complex mixtures such as botanical extracts, a Magnetic Microbead Affinity Selection Screening (MagMASS) procedure was developed. This technique utilizes target proteins immobilized on magnetic beads for rapid bioaffinity isolation of ligands from complex mixtures. A MagMASS method was developed and validated for 15-lipoxygenase. As a proof of concept, several North American prairie plants used medicinally by Native Americans were extracted with MeOH and screened. A hit from an extract of Proserpinaca palustris, also known as mermaid weed, was flagged for further characterization using high-resolution tandem mass spectrometry, dereplication, and identification using XCMS online. Through the application of high-resolution product ion tandem mass spectrometry, comparison with natural product databases and confirmation using standards, the hit was identified as quercitrin, which is a known inhibitor of 15-lipoxygenase. The overall workflow of MagMASS is faster and more amendable to automation than alternative methods designed for screening botanical extracts or complex mixtures of combinatorial libraries. PMID:27802026

Structure-based design of an osteoclast-selective, nonpeptide Src homology 2 inhibitor with in vivo antiresorptive activity

Science.gov (United States)

Shakespeare, William; Yang, Michael; Bohacek, Regine; Cerasoli, Franklin; Stebbins, Karin; Sundaramoorthi, Raji; Azimioara, Mihai; Vu, Chi; Pradeepan, Selvi; Metcalf, Chester; Haraldson, Chad; Merry, Taylor; Dalgarno, David; Narula, Surinder; Hatada, Marcos; Lu, Xiaode; van Schravendijk, Marie Rose; Adams, Susan; Violette, Shelia; Smith, Jeremy; Guan, Wei; Bartlett, Catherine; Herson, Jay; Iuliucci, John; Weigele, Manfred; Sawyer, Tomi

2000-01-01

Targeted disruption of the pp60src (Src) gene has implicated this tyrosine kinase in osteoclast-mediated bone resorption and as a therapeutic target for the treatment of osteoporosis and other bone-related diseases. Herein we describe the discovery of a nonpeptide inhibitor (AP22408) of Src that demonstrates in vivo antiresorptive activity. Based on a cocrystal structure of the noncatalytic Src homology 2 (SH2) domain of Src complexed with citrate [in the phosphotyrosine (pTyr) binding pocket], we designed 3′,4′-diphosphonophenylalanine (Dpp) as a pTyr mimic. In addition to its design to bind Src SH2, the Dpp moiety exhibits bone-targeting properties that confer osteoclast selectivity, hence minimizing possible undesired effects on other cells that have Src-dependent activities. The chemical structure AP22408 also illustrates a bicyclic template to replace the post-pTyr sequence of cognate Src SH2 phosphopeptides such as Ac-pTyr-Glu-Glu-Ile (1). An x-ray structure of AP22408 complexed with Lck (S164C) SH2 confirmed molecular interactions of both the Dpp and bicyclic template of AP22408 as predicted from molecular modeling. Relative to the cognate phosphopeptide, AP22408 exhibits significantly increased Src SH2 binding affinity (IC50 = 0.30 μM for AP22408 and 5.5 μM for 1). Furthermore, AP22408 inhibits rabbit osteoclast-mediated resorption of dentine in a cellular assay, exhibits bone-targeting properties based on a hydroxyapatite adsorption assay, and demonstrates in vivo antiresorptive activity in a parathyroid hormone-induced rat model. PMID:10944210

Effect of proton pump inhibitors on the serum concentrations of the selective serotonin reuptake inhibitors citalopram, escitalopram, and sertraline.

Science.gov (United States)

Gjestad, Caroline; Westin, Andreas A; Skogvoll, Eirik; Spigset, Olav

2015-02-01

The selective serotonin reuptake inhibitors (SSRIs) citalopram, escitalopram, and sertraline are all metabolized by the cytochrome P-450 isoenzyme CYP2C19, which is inhibited by the proton pump inhibitors (PPIs) omeprazole, esomeprazole, lansoprazole, and pantoprazole. The aim of the present study was to evaluate the effect of these PPIs on the serum concentrations of citalopram, escitalopram, and sertraline. Serum concentrations from patients treated with citalopram, escitalopram, or sertraline were obtained from a routine therapeutic drug monitoring database, and samples from subjects concomitantly using PPIs were identified. Dose-adjusted SSRI serum concentrations were calculated to compare data from those treated and those not treated with PPIs. Citalopram concentrations were significantly higher in patients treated with omeprazole (+35.3%; P Escitalopram concentrations were significantly higher in patients treated with omeprazole (+93.9%; P escitalopram is affected to a greater extent than are citalopram and sertraline. When omeprazole or esomeprazole are used in combination with escitalopram, a 50% dose reduction of the latter should be considered.

Tyrosine kinase inhibitors and mesenchymal stromal cells: effects on self-renewal, commitment and functions

Science.gov (United States)

Borriello, Adriana; Caldarelli, Ilaria; Bencivenga, Debora; Stampone, Emanuela; Perrotta, Silverio; Oliva, Adriana; Ragione, Fulvio Della

2017-01-01

The hope of selectively targeting cancer cells by therapy and eradicating definitively malignancies is based on the identification of pathways or metabolisms that clearly distinguish “normal” from “transformed” phenotypes. Some tyrosine kinase activities, specifically unregulated and potently activated in malignant cells, might represent important targets of therapy. Consequently, tyrosine kinase inhibitors (TKIs) might be thought as the “vanguard” of molecularly targeted therapy for human neoplasias. Imatinib and the successive generations of inhibitors of Bcr-Abl1 kinase, represent the major successful examples of TKI use in cancer treatment. Other tyrosine kinases have been selected as targets of therapy, but the efficacy of their inhibition, although evident, is less definite. Two major negative effects exist in this therapeutic strategy and are linked to the specificity of the drugs and to the role of the targeted kinase in non-malignant cells. In this review, we will discuss the data available on the TKIs effects on the metabolism and functions of mesenchymal stromal cells (MSCs). MSCs are widely distributed in human tissues and play key physiological roles; nevertheless, they might be responsible for important pathologies. At present, bone marrow (BM) MSCs have been studied in greater detail, for both embryological origins and functions. The available data are evocative of an unexpected degree of complexity and heterogeneity of BM-MSCs. It is conceivable that this grade of intricacy occurs also in MSCs of other organs. Therefore, in perspective, the negative effects of TKIs on MSCs might represent a critical problem in long-term cancer therapies based on such inhibitors. PMID:27750212

BET Bromodomain Inhibitors with One-Step Synthesis Discovered from Virtual Screen.

Science.gov (United States)

Ayoub, Alex M; Hawk, Laura M L; Herzig, Ryan J; Jiang, Jiewei; Wisniewski, Andrea J; Gee, Clifford T; Zhao, Peiliang; Zhu, Jin-Yi; Berndt, Norbert; Offei-Addo, Nana K; Scott, Thomas G; Qi, Jun; Bradner, James E; Ward, Timothy R; Schönbrunn, Ernst; Georg, Gunda I; Pomerantz, William C K

2017-06-22

Chemical inhibition of epigenetic regulatory proteins BrdT and Brd4 is emerging as a promising therapeutic strategy in contraception, cancer, and heart disease. We report an easily synthesized dihydropyridopyrimidine pan-BET inhibitor scaffold, which was uncovered via a virtual screen followed by testing in a fluorescence anisotropy assay. Dihydropyridopyimidine 3 was subjected to further characterization and is highly selective for the BET family of bromodomains. Structure-activity relationship data and ligand deconstruction highlight the importance of the substitution of the uracil moiety for potency and selectivity. Compound 3 was also cocrystallized with Brd4 for determining the ligand binding pose and rationalizing subsequent structure-activity data. An additional series of dihydropyridopyrimidines was synthesized to exploit the proximity of a channel near the ZA loop of Brd4, leading to compounds with submicromolar affinity and cellular target engagement. Given these findings, novel and easily synthesized inhibitors are being introduced to the growing field of bromodomain inhibitor development.

BET Bromodomain Inhibitors with One-Step Synthesis Discovered from Virtual Screen

Energy Technology Data Exchange (ETDEWEB)

Ayoub, Alex M.; Hawk, Laura M.L.; Herzig, Ryan J.; Jiang, Jiewei; Wisniewski, Andrea J.; Gee, Clifford T.; Zhao, Peiliang; Zhu, Jin-Yi; Berndt, Norbert; Offei-Addo, Nana K.; Scott, Thomas G.; Qi, Jun; Bradner, James E.; Ward, Timothy R.; Schönbrunn, Ernst; Georg, Gunda I.; Pomerantz, William C.K. (Moffitt); (UMM); (Harvard-Med)

2017-06-06

Chemical inhibition of epigenetic regulatory proteins BrdT and Brd4 is emerging as a promising therapeutic strategy in contraception, cancer, and heart disease. We report an easily synthesized dihydropyridopyrimidine pan-BET inhibitor scaffold, which was uncovered via a virtual screen followed by testing in a fluorescence anisotropy assay. Dihydropyridopyimidine 3 was subjected to further characterization and is highly selective for the BET family of bromodomains. Structure–activity relationship data and ligand deconstruction highlight the importance of the substitution of the uracil moiety for potency and selectivity. Compound 3 was also cocrystallized with Brd4 for determining the ligand binding pose and rationalizing subsequent structure–activity data. An additional series of dihydropyridopyrimidines was synthesized to exploit the proximity of a channel near the ZA loop of Brd4, leading to compounds with submicromolar affinity and cellular target engagement. Given these findings, novel and easily synthesized inhibitors are being introduced to the growing field of bromodomain inhibitor development.

Targeting Signaling Pathways in Epithelial Ovarian Cancer

Directory of Open Access Journals (Sweden)

Johannes Haybaeck

2013-05-01

Full Text Available Ovarian carcinoma (OC is the most lethal gynecological malignancy. Response to platinum-based chemotherapy is poor in some patients and, thus, current research is focusing on new therapy options. The various histological types of OC are characterized by distinctive molecular genetic alterations that are relevant for ovarian tumorigenesis. The understanding of these molecular pathways is essential for the development of novel therapeutic strategies. Purpose: We want to give an overview on the molecular genetic changes of the histopathological types of OC and their role as putative therapeutic targets. In Depth Review of Existing Data: In 2012, the vascular endothelial growth factor (VEGF inhibitor, bevacizumab, was approved for OC treatment. Bevacizumab has shown promising results as single agent and in combination with conventional chemotherapy, but its target is not distinctive when analyzed before treatment. At present, mammalian target of rapamycin (mTOR inhibitors, poly-ADP-ribose polymerase (PARP inhibitors and components of the EGFR pathway are in the focus of clinical research. Interestingly, some phytochemical substances show good synergistic effects when used in combination with chemotherapy. Conclusion: Ongoing studies of targeted agents in conjunction with chemotherapy will show whether there are alternative options to bevacizumab available for OC patients. Novel targets which can be assessed before therapy to predict efficacy are needed. The assessment of therapeutic targets is continuously improved by molecular pathological analyses on tumor tissue. A careful selection of patients for personalized treatment will help to reduce putative side effects and toxicity.

Feature Extraction and Selection Strategies for Automated Target Recognition

Science.gov (United States)

Greene, W. Nicholas; Zhang, Yuhan; Lu, Thomas T.; Chao, Tien-Hsin

2010-01-01

Several feature extraction and selection methods for an existing automatic target recognition (ATR) system using JPLs Grayscale Optical Correlator (GOC) and Optimal Trade-Off Maximum Average Correlation Height (OT-MACH) filter were tested using MATLAB. The ATR system is composed of three stages: a cursory region of-interest (ROI) search using the GOC and OT-MACH filter, a feature extraction and selection stage, and a final classification stage. Feature extraction and selection concerns transforming potential target data into more useful forms as well as selecting important subsets of that data which may aide in detection and classification. The strategies tested were built around two popular extraction methods: Principal Component Analysis (PCA) and Independent Component Analysis (ICA). Performance was measured based on the classification accuracy and free-response receiver operating characteristic (FROC) output of a support vector machine(SVM) and a neural net (NN) classifier.

Does selective serotonin reuptake inhibitor (SSRI) fluoxetine affects mussel Mytilus galloprovincialis?

International Nuclear Information System (INIS)

Gonzalez-Rey, Maria; Bebianno, Maria João

2013-01-01

Fluoxetine (FLX) the active pharmaceutical ingredient (API) in Prozac ® is a widely prescribed psychoactive drug which ubiquitous occurrence in the aquatic environment is associated to a poor removal rate in waste-water treatment plant (WWTP) systems. This API acts as a selective serotonin reuptake inhibitor (SSRI) frequently reported to cause disrupting effects in non-target species. The objective of this study includes a multibiomarker response evaluation on mussel Mytilus galloprovincialis during two weeks exposure to 75 ng L −1 FLX assessing antioxidant enzymes activities – superoxide dismutase (SOD), catalase (CAT) and glutathione-S-transferase (GST); lipid peroxidation (LPO), acetylcholinesterase (AChE) neurotoxic response and endocrine disruption through alkali-labile phosphates (ALP) indirect measurement of vitellogenin-like proteins. Results show transient tissue-specific enzymatic responses and damage affecting mostly mussel gills. However, the clear ALP levels inhibition throughout time in both sex-differentiated gonads gives evidence to FLX reinforced action as an endocrine disruptor rather than an oxidative or neurotoxic inducer. - Highlights: ► Short-time exposure of Mytilus galloprovincialis to antidepressant fluoxetine. ► Tissue-specific transient antioxidant enzymes activities alteration. ► Lipid peroxidation (LPO) induction in exposed-tissues. ► Acetylcholinesterase (AChE) activity upregulation in exposed gills. ► ALP levels downregulation in exposed sex-differentiated mussels. - Exposure to 75 ng L −1 antidepressant fluoxetine (FLX) induces tissue-specific multibiomarker responses alteration in mussel Mytilus galloprovincialis.

Effects of Mode of Target Task Selection on Learning about Plants in a Mobile Learning Environment: Effortful Manual Selection versus Effortless QR-Code Selection

Science.gov (United States)

Gao, Yuan; Liu, Tzu-Chien; Paas, Fred

2016-01-01

This study compared the effects of effortless selection of target plants using quick respond (QR) code technology to effortful manual search and selection of target plants on learning about plants in a mobile device supported learning environment. In addition, it was investigated whether the effectiveness of the 2 selection methods was…

Discovery of the first selective inhibitor of excitatory amino acid transporter subtype 1

DEFF Research Database (Denmark)

Jensen, Anders Asbjørn; Erichsen, Mette Navy; Nielsen, Christina Wøhlk

2009-01-01

The discovery of the first class of subtype-selective inhibitors of the human excitatory amino acid transporter subtype 1 (EAAT1) and its rat orthologue GLAST is reported. An opening structure-activity relationship of 25 analogues is presented that addresses the influence of substitutions at the 4......- and 7-positions of the parental skeleton 2-amino-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3-carbonitrile. The most potent analogue 1o displays high nanomolar inhibitory activity at EAAT1 and a >400-fold selectivity over EAAT2 and EAAT3, making it a highly valuable pharmacological tool....

Novel selective inhibitor of Leishmania (Leishmania) amazonensis arginase.

Science.gov (United States)

da Silva, Edson R; Boechat, Nubia; Pinheiro, Luiz C S; Bastos, Monica M; Costa, Carolina C P; Bartholomeu, Juliana C; da Costa, Talita H

2015-11-01

Arginase is a glycosomal enzyme in Leishmania that is involved in polyamine and trypanothione biosynthesis. The central role of arginase in Leishmania (Leishmania) amazonensis was demonstrated by the generation of two mutants: one with an arginase lacking the glycosomal addressing signal and one in which the arginase-coding gene was knocked out. Both of these mutants exhibited decreased infectivity. Thus, arginase seems to be a potential drug target for Leishmania treatment. In an attempt to search for arginase inhibitors, 29 derivatives of the [1,2,4]triazolo[1,5-a]pyrimidine system were tested against Leishmania (Leishmania) amazonensis arginase in vitro. The [1,2,4]triazolo[1,5-a]pyrimidine scaffold containing R1  = CF3 exhibited greater activity against the arginase rather than when the substituent R1  = CH3 in the 2-position. The novel compound 2-(5-methyl-2-(trifluoromethyl)-[1,2,4]triazolo[1,5-a]pyrimidin-7-yl)hydrazinecarbothioamide (30) was the most potent, inhibiting arginase by a non-competitive mechanism, with the Ki and IC50 values for arginase inhibition estimated to be 17 ± 1 μm and 16.5 ± 0.5 μm, respectively. These results can guide the development of new drugs against leishmaniasis based on [1,2,4]triazolo[1,5-a]pyrimidine derivatives targeting the arginase enzyme. © 2015 John Wiley & Sons A/S.

Transcriptional changes associated with resistance to inhibitors of epidermal growth factor receptor revealed using metaanalysis

International Nuclear Information System (INIS)

Younis, Sidra; Javed, Qamar; Blumenberg, Miroslav

2015-01-01

EGFR is important in maintaining metabolic homeostasis in healthy cells, but in tumors it activates downstream signaling pathways, causing proliferation, angiogenesis, invasion and metastasis. Consequently, EGFR is targeted in cancers using reversible, irreversible or antibody inhibitors. Unfortunately, tumors develop inhibitor resistance by mutations or overexpressing EGFR, or its ligand, or activating secondary, EGFR-independent pathways. Here we present a global metaanalysis comparing transcriptional profiles from matched pairs of EGFR inhibitor-sensitive vs. -resistant cell lines, using 15 datasets comprising 274 microarrays. We also analyzed separately pairs of cell lines derived using reversible, irreversible or antibody inhibitors. The metaanalysis identifies commonalities in cell lines resistant to EGFR inhibitors: in sensitive cell lines, the ontological categories involving the ErbB receptors pathways, cell adhesion and lipid metabolism are overexpressed; however, resistance to EGFR inhibitors is associated with overexpression of genes for ErbB receptors-independent oncogenic pathways, regulation of cell motility, energy metabolism, immunity especially inflammatory cytokines biosynthesis, cell cycle and responses to exogenous and endogenous stimuli. Specifically in Gefitinib-resistant cell lines, the immunity-associated genes are overexpressed, whereas in Erlotinib-resistant ones so are the mitochondrial genes and processes. Unexpectedly, lines selected using EGFR-targeting antibodies overexpress different gene ontologies from ones selected using kinase inhibitors. Specifically, they have reduced expression of genes for proliferation, chemotaxis, immunity and angiogenesis. This metaanalysis suggests that ‘combination therapies’ can improve cancer treatment outcomes. Potentially, use of mitochondrial blockers with Erlotinib, immunity blockers with Gefitinib, tyrosine kinase inhibitors with antibody inhibitors, may have better chance of avoiding

Helicobacter pylori and risk of upper gastrointestinal bleeding among users of selective serotonin reuptake inhibitors

DEFF Research Database (Denmark)

Dall, Michael; Schaffalitzky de Muckadell, Ove B; Møller Hansen, Jane

2011-01-01

A number of studies have reported a possible association between use of selective serotonin reuptake inhibitors (SSRIs) and serious upper gastrointestinal bleeding (UGB). We conducted this case-control study to assess if Helicobacter pylori (H. pylori) potentiates the risk of serious UGB in SSRI ...

Phenotypic Screening Approaches to Develop Aurora Kinase Inhibitors: Drug Discovery Perspectives.

Science.gov (United States)

Marugán, Carlos; Torres, Raquel; Lallena, María José

2015-01-01

Targeting mitotic regulators as a strategy to fight cancer implies the development of drugs against key proteins, such as Aurora-A and -B. Current drugs, which target mitosis through a general mechanism of action (stabilization/destabilization of microtubules), have several side effects (neutropenia, alopecia, and emesis). Pharmaceutical companies aim at avoiding these unwanted effects by generating improved and selective drugs that increase the quality of life of the patients. However, the development of these drugs is an ambitious task that involves testing thousands of compounds through biochemical and cell-based assays. In addition, molecules usually target complex biological processes, involving several proteins and different molecular pathways, further emphasizing the need for high-throughput screening techniques and multiplexing technologies in order to identify drugs with the desired phenotype. We will briefly describe two multiplexing technologies [high-content imaging (HCI) and flow cytometry] and two key processes for drug discovery research (assay development and validation) following our own published industry quality standards. We will further focus on HCI as a useful tool for phenotypic screening and will provide a concrete example of HCI assay to detect Aurora-A or -B selective inhibitors discriminating the off-target effects related to the inhibition of other cell cycle or non-cell cycle key regulators. Finally, we will describe other assays that can help to characterize the in vitro pharmacology of the inhibitors.

Fragment-based approaches to the discovery of kinase inhibitors.

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Mortenson, Paul N; Berdini, Valerio; O'Reilly, Marc

2014-01-01

Protein kinases are one of the most important families of drug targets, and aberrant kinase activity has been linked to a large number of disease areas. Although eminently targetable using small molecules, kinases present a number of challenges as drug targets, not least obtaining selectivity across such a large and relatively closely related target family. Fragment-based drug discovery involves screening simple, low-molecular weight compounds to generate initial hits against a target. These hits are then optimized to more potent compounds via medicinal chemistry, usually facilitated by structural biology. Here, we will present a number of recent examples of fragment-based approaches to the discovery of kinase inhibitors, detailing the construction of fragment-screening libraries, the identification and validation of fragment hits, and their optimization into potent and selective lead compounds. The advantages of fragment-based methodologies will be discussed, along with some of the challenges associated with using this route. Finally, we will present a number of key lessons derived both from our own experience running fragment screens against kinases and from a large number of published studies.

A novel small molecule inhibitor of hepatitis C virus entry.

Directory of Open Access Journals (Sweden)

Carl J Baldick

Full Text Available Small molecule inhibitors of hepatitis C virus (HCV are being developed to complement or replace treatments with pegylated interferons and ribavirin, which have poor response rates and significant side effects. Resistance to these inhibitors emerges rapidly in the clinic, suggesting that successful therapy will involve combination therapy with multiple inhibitors of different targets. The entry process of HCV into hepatocytes represents another series of potential targets for therapeutic intervention, involving viral structural proteins that have not been extensively explored due to experimental limitations. To discover HCV entry inhibitors, we utilized HCV pseudoparticles (HCVpp incorporating E1-E2 envelope proteins from a genotype 1b clinical isolate. Screening of a small molecule library identified a potent HCV-specific triazine inhibitor, EI-1. A series of HCVpp with E1-E2 sequences from various HCV isolates was used to show activity against all genotype 1a and 1b HCVpp tested, with median EC50 values of 0.134 and 0.027 µM, respectively. Time-of-addition experiments demonstrated a block in HCVpp entry, downstream of initial attachment to the cell surface, and prior to or concomitant with bafilomycin inhibition of endosomal acidification. EI-1 was equally active against cell-culture adapted HCV (HCVcc, blocking both cell-free entry and cell-to-cell transmission of virus. HCVcc with high-level resistance to EI-1 was selected by sequential passage in the presence of inhibitor, and resistance was shown to be conferred by changes to residue 719 in the carboxy-terminal transmembrane anchor region of E2, implicating this envelope protein in EI-1 susceptibility. Combinations of EI-1 with interferon, or inhibitors of NS3 or NS5A, resulted in additive to synergistic activity. These results suggest that inhibitors of HCV entry could be added to replication inhibitors and interferons already in development.

Insights into the molecular evolution of peptidase inhibitors in arthropods.

Science.gov (United States)

Alonso, Joaquin; Martinez, Manuel

2017-01-01

Peptidase inhibitors are key proteins involved in the control of peptidases. In arthropods, peptidase inhibitors modulate the activity of peptidases involved in endogenous physiological processes and peptidases of the organisms with which they interact. Exploring available arthropod genomic sequences is a powerful way to obtain the repertoire of peptidase inhibitors in every arthropod species and to understand the evolutionary mechanisms involved in the diversification of this kind of proteins. A genomic comparative analysis of peptidase inhibitors in species belonging to different arthropod taxonomic groups was performed. The results point out: i) species or clade-specific presence is shown for several families of peptidase inhibitors; ii) multidomain peptidase inhibitors are commonly found in many peptidase inhibitor families; iii) several families have a wide range of members in different arthropod species; iv) several peptidase inhibitor families show species-specific (or clade-specific) gene family expansions; v) functional divergence may be assumed for particular clades; vi) passive expansions may be used by natural selection to fix adaptations. In conclusion, conservation and divergence of duplicated genes and the potential recruitment as peptidase inhibitors of proteins from other families are the main mechanisms used by arthropods to fix diversity. This diversity would be associated to the control of target peptidases and, as consequence, to adapt to specific environments.

Hot spot-based design of small-molecule inhibitors for protein-protein interactions.

Science.gov (United States)

Guo, Wenxing; Wisniewski, John A; Ji, Haitao

2014-06-01

Protein-protein interactions (PPIs) are important targets for the development of chemical probes and therapeutic agents. From the initial discovery of the existence of hot spots at PPI interfaces, it has been proposed that hot spots might provide the key for developing small-molecule PPI inhibitors. However, there has been no review on the ways in which the knowledge of hot spots can be used to achieve inhibitor design, nor critical examination of successful examples. This Digest discusses the characteristics of hot spots and the identification of druggable hot spot pockets. An analysis of four examples of hot spot-based design reveals the importance of this strategy in discovering potent and selective PPI inhibitors. A general procedure for hot spot-based design of PPI inhibitors is outlined. Copyright © 2014 Elsevier Ltd. All rights reserved.

Novel targeted therapeutics: inhibitors of MDM2, ALK and PARP

Directory of Open Access Journals (Sweden)

Hsueh Chung-Tsen

2011-04-01

Full Text Available Abstract We reviewed preclinical data and clinical development of MDM2 (murine double minute 2, ALK (anaplastic lymphoma kinase and PARP (poly [ADP-ribose] polymerase inhibitors. MDM2 binds to p53, and promotes degradation of p53 through ubiquitin-proteasome degradation. JNJ-26854165 and RO5045337 are 2 small-molecule inhibitors of MDM2 in clinical development. ALK is a transmembrane protein and a member of the insulin receptor tyrosine kinases. EML4-ALK fusion gene is identified in approximately 3-13% of non-small cell lung cancer (NSCLC. Early-phase clinical studies with Crizotinib, an ALK inhibitor, in NSCLC harboring EML4-ALK have demonstrated promising activity with high response rate and prolonged progression-free survival. PARPs are a family of nuclear enzymes that regulates the repair of DNA single-strand breaks through the base excision repair pathway. Randomized phase II study has shown adding PARP-1 inhibitor BSI-201 to cytotoxic chemotherapy improves clinical outcome in patients with triple-negative breast cancer. Olaparib, another oral small-molecule PARP inhibitor, demonstrated encouraging single-agent activity in patients with advanced breast or ovarian cancer. There are 5 other PARP inhibitors currently under active clinical investigation.

Dissecting patterns of preparatory activity in the frontal eye fields during pursuit target selection.

Science.gov (United States)

Raghavan, Ramanujan T; Joshua, Mati

2017-10-01

We investigated the composition of preparatory activity of frontal eye field (FEF) neurons in monkeys performing a pursuit target selection task. In response to the orthogonal motion of a large and a small reward target, monkeys initiated pursuit biased toward the direction of large reward target motion. FEF neurons exhibited robust preparatory activity preceding movement initiation in this task. Preparatory activity consisted of two components, ramping activity that was constant across target selection conditions, and a flat offset in firing rates that signaled the target selection condition. Ramping activity accounted for 50% of the variance in the preparatory activity and was linked most strongly, on a trial-by-trial basis, to pursuit eye movement latency rather than to its direction or gain. The offset in firing rates that discriminated target selection conditions accounted for 25% of the variance in the preparatory activity and was commensurate with a winner-take-all representation, signaling the direction of large reward target motion rather than a representation that matched the parameters of the upcoming movement. These offer new insights into the role that the frontal eye fields play in target selection and pursuit control. They show that preparatory activity in the FEF signals more strongly when to move rather than where or how to move and suggest that structures outside the FEF augment its contributions to the target selection process. NEW & NOTEWORTHY We used the smooth eye movement pursuit system to link between patterns of preparatory activity in the frontal eye fields and movement during a target selection task. The dominant pattern was a ramping signal that did not discriminate between selection conditions and was linked, on trial-by-trial basis, to movement latency. A weaker pattern was composed of a constant signal that discriminated between selection conditions but was only weakly linked to the movement parameters. Copyright © 2017 the American

A Novel, Broad-Spectrum Inhibitor of Enterovirus Replication That Targets Host Cell Factor Phosphatidylinositol 4-Kinase IIIβ

Science.gov (United States)

van der Schaar, Hilde M.; Leyssen, Pieter; Thibaut, Hendrik J.; de Palma, Armando; van der Linden, Lonneke; Lanke, Kjerstin H. W.; Lacroix, Céline; Verbeken, Erik; Conrath, Katja; MacLeod, Angus M.; Mitchell, Dale R.; Palmer, Nicholas J.; van de Poël, Hervé; Andrews, Martin

2013-01-01

Despite their high clinical and socioeconomic impacts, there is currently no approved antiviral therapy for the prophylaxis or treatment of enterovirus infections. Here we report on a novel inhibitor of enterovirus replication, compound 1, 2-fluoro-4-(2-methyl-8-(3-(methylsulfonyl)benzylamino)imidazo[1,2-a]pyrazin-3-yl)phenol. This compound exhibited a broad spectrum of antiviral activity, as it inhibited all tested species of enteroviruses and rhinoviruses, with 50% effective concentrations ranging between 4 and 71 nM. After a lengthy resistance selection process, coxsackievirus mutants resistant to compound 1 were isolated that carried substitutions in their 3A protein. Remarkably, the same substitutions were recently shown to provide resistance to inhibitors of phosphatidylinositol 4-kinase IIIβ (PI4KIIIβ), a lipid kinase that is essential for enterovirus replication, suggesting that compound 1 may also target this host factor. Accordingly, compound 1 directly inhibited PI4KIIIβ in an in vitro kinase activity assay. Furthermore, the compound strongly reduced the PI 4-phosphate levels of the Golgi complex in cells. Rescue of coxsackievirus replication in the presence of compound 1 by a mutant PI4KIIIβ carrying a substitution in its ATP-binding pocket revealed that the compound directly binds the kinase at this site. Finally, we determined that an analogue of compound 1, 3-(3-fluoro-4-methoxyphenyl)-2-methyl-N-(pyridin-4-ylmethyl)imidazo[1,2-a]pyrazin-8-amine, is well tolerated in mice and has a dose-dependent protective activity in a coxsackievirus serotype B4-induced pancreatitis model. PMID:23896472

Neratinib, A Novel HER2-Targeted Tyrosine Kinase Inhibitor.

Science.gov (United States)

Tiwari, Shruti Rakesh; Mishra, Prasun; Abraham, Jame

2016-10-01

HER2 gene amplification and receptor overexpression is identified in 20% to 25% of human breast cancers. Use of targeted therapy for HER2-amplified breast cancer has led to improvements in disease-free and overall survival in this subset of patients. Neratinib is an oral pan HER inhibitor, that irreversibly inhibits the tyrosine kinase activity of epidermal growth factor receptor (EGFR or HER1), HER2, and HER4, which leads to reduced phosphorylation and activation of downstream signaling pathways. Neratinib is currently being tested in a number of clinical trials for its safety and efficacy in lung cancer, and colorectal, bladder, and breast cancers. In this review we discuss the available phase I, II, and III data for use of neratinib in the metastatic, adjuvant, neoadjuvant, and extended adjuvant settings along with the ongoing clinical trials of neratinib in breast cancer. We also elaborate on the side effect profile of this relatively new drug and provide guidelines for its use in clinical practice. Copyright © 2016 Elsevier Inc. All rights reserved.

Design and Development of a Series of Potent and Selective Type II Inhibitors of CDK8

Science.gov (United States)

2016-01-01

Using Sorafenib as a starting point, a series of potent and selective inhibitors of CDK8 was developed. When cocrystallized with CDK8 and cyclin C, these compounds exhibit a Type-II (DMG-out) binding mode. PMID:27326333

Docking based 3d-QSAR studies applied at the BRAF inhibitors to understand the binding mechanism

International Nuclear Information System (INIS)

Mahmood, U.; Haq, Z.U.

2011-01-01

BRAF is a great therapeutic target in a wide variety of human cancers. It is the member of Ras Activating Factor (RAF) family of serine/throenine kinase. The mutated form of the BRAF has diverted all the attention towards itself because of increase severity and elevated kinase activity. The RAF signal transduction cascade is a conserved protein pathway that is involved in cell cycle progression and apoptosis. The ERK regulates phosphorylation of different proteins either in cytosol or in nucleus but disorders in ERK signaling pathway cause mutation in BRAF. This cascade in these cells may provide selection of mutated BRAF in which valine is substituted with glutamatic acid at position 600. This mutation occurs in activation loop. A number of inhibitors reported to target different members of RAF, some of them have potential to target the BRAF as well. Major reason for failure of previously reported inhibitors was due to the highly conserved sequence and confirmation of catalytic cleft which is always a center of consideration for binding of inhibitors to suppress the kinase activity. This is the first attempt to study and understand the BARF inhibitors - protein interactions in detail by utilizing 3D-QSAR and molecular docking techniques. Most reliable techniques of 3D QSAR i.e Comparative Molecular Field Analysis (CoMFA) and Comparative Molecular Similarity Indices Analysis (CoMSIA) were applied for three different data sets. The data sets selected for better evaluation of BRAF inhibitors belongs to 2, 6-Disubstituted Pyrazine, Pyridoimidazolones and its derivatives. Our models would offer help to better understand the structure-activity relationships that exist for these classes of compounds and also facilitate the design of novel inhibitors with good chemical diversity. (Author)

Structural insight into exosite binding and discovery of novel exosite inhibitors of botulinum neurotoxin serotype A through in silico screening

Science.gov (United States)

Hu, Xin; Legler, Patricia M.; Southall, Noel; Maloney, David J.; Simeonov, Anton; Jadhav, Ajit

2014-07-01

Botulinum neurotoxin serotype A (BoNT/A) is the most lethal toxin among the Tier 1 Select Agents. Development of potent and selective small molecule inhibitors against BoNT/A zinc metalloprotease remains a challenging problem due to its exceptionally large substrate binding surface and conformational plasticity. The exosites of the catalytic domain of BoNT/A are intriguing alternative sites for small molecule intervention, but their suitability for inhibitor design remains largely unexplored. In this study, we employed two recently identified exosite inhibitors, D-chicoric acid and lomofungin, to probe the structural features of the exosites and molecular mechanisms of synergistic inhibition. The results showed that D-chicoric acid favors binding at the α-exosite, whereas lomofungin preferentially binds at the β-exosite by mimicking the substrate β-sheet binding interaction. Molecular dynamics simulations and binding interaction analysis of the exosite inhibitors with BoNT/A revealed key elements and hotspots that likely contribute to the inhibitor binding and synergistic inhibition. Finally, we performed database virtual screening for novel inhibitors of BoNT/A targeting the exosites. Hits C1 and C2 showed non-competitive inhibition and likely target the α- and β-exosites, respectively. The identified exosite inhibitors may provide novel candidates for structure-based development of therapeutics against BoNT/A intoxication.

4-Hydroxyphenylpyruvate Dioxygenase Inhibitors: From Chemical Biology to Agrochemicals.

Science.gov (United States)

Ndikuryayo, Ferdinand; Moosavi, Behrooz; Yang, Wen-Chao; Yang, Guang-Fu

2017-10-04

The development of new herbicides is receiving considerable attention to control weed biotypes resistant to current herbicides. Consequently, new enzymes are always desired as targets for herbicide discovery. 4-Hydroxyphenylpyruvate dioxygenase (HPPD, EC 1.13.11.27) is an enzyme engaged in photosynthetic activity and catalyzes the transformation of 4-hydroxyphenylpyruvic acid (HPPA) into homogentisic acid (HGA). HPPD inhibitors constitute a promising area of discovery and development of innovative herbicides with some advantages, including excellent crop selectivity, low application rates, and broad-spectrum weed control. HPPD inhibitors have been investigated for agrochemical interests, and some of them have already been commercialized as herbicides. In this review, we mainly focus on the chemical biology of HPPD, discovery of new potential inhibitors, and strategies for engineering transgenic crops resistant to current HPPD-inhibiting herbicides. The conclusion raises some relevant gaps for future research directions.

Discovery of HDAC inhibitors with potent activity against multiple malaria parasite life cycle stages.

Science.gov (United States)

Hansen, Finn K; Sumanadasa, Subathdrage D M; Stenzel, Katharina; Duffy, Sandra; Meister, Stephan; Marek, Linda; Schmetter, Rebekka; Kuna, Krystina; Hamacher, Alexandra; Mordmüller, Benjamin; Kassack, Matthias U; Winzeler, Elizabeth A; Avery, Vicky M; Andrews, Katherine T; Kurz, Thomas

2014-07-23

In this work we investigated the antiplasmodial activity of a series of HDAC inhibitors containing an alkoxyamide connecting-unit linker region. HDAC inhibitor 1a (LMK235), previously shown to be a novel and specific inhibitor of human HDAC4 and 5, was used as a starting point to rapidly construct a mini-library of HDAC inhibitors using a straightforward solid-phase supported synthesis. Several of these novel HDAC inhibitors were found to have potent in vitro activity against asexual stage Plasmodium falciparum malaria parasites. Representative compounds were shown to hyperacetylate P. falciparum histones and to inhibit deacetylase activity of recombinant PfHDAC1 and P. falciparum nuclear extracts. All compounds were also screened in vitro for activity against Plasmodium berghei exo-erythrocytic stages and selected compounds were further tested against late stage (IV and V) P. falciparum gametocytes. Of note, some compounds showed nanomolar activity against all three life cycle stages tested (asexual, exo-erythrocytic and gametocyte stages) and several compounds displayed significantly increased parasite selectivity compared to the reference HDAC inhibitor suberoylanilide hydroxamic acid (SAHA). These data suggest that it may be possible to develop HDAC inhibitors that target multiple malaria parasite life cycle stages. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Discovery of a Novel Inhibitor of the Hedgehog Signaling Pathway through Cell-based Compound Discovery and Target Prediction.

Science.gov (United States)

Kremer, Lea; Schultz-Fademrecht, Carsten; Baumann, Matthias; Habenberger, Peter; Choidas, Axel; Klebl, Bert; Kordes, Susanne; Schöler, Hans R; Sterneckert, Jared; Ziegler, Slava; Schneider, Gisbert; Waldmann, Herbert

2017-10-09

Cell-based assays enable monitoring of small-molecule bioactivity in a target-agnostic manner and help uncover new biological mechanisms. Subsequent identification and validation of the small-molecule targets, typically employing proteomics techniques, is very challenging and limited, in particular if the targets are membrane proteins. Herein, we demonstrate that the combination of cell-based bioactive-compound discovery with cheminformatic target prediction may provide an efficient approach to accelerate the process and render target identification and validation more efficient. Using a cell-based assay, we identified the pyrazolo-imidazole smoothib as a new inhibitor of hedgehog (Hh) signaling and an antagonist of the protein smoothened (SMO) with a novel chemotype. Smoothib targets the heptahelical bundle of SMO, prevents its ciliary localization, reduces the expression of Hh target genes, and suppresses the growth of Ptch +/- medulloblastoma cells. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Proteinaceous alpha-araylase inhibitors

DEFF Research Database (Denmark)

Svensson, Birte; Fukuda, Kenji; Nielsen, P.K.

2004-01-01

-amylase inhibitors belong to seven different protein structural families, most of which also contain evolutionary related proteins without inhibitory activity. Two families include bifunctional inhibitors acting both on alpha-amylases and proteases. High-resolution structures are available of target alpha...

Integrative analysis to select cancer candidate biomarkers to targeted validation

Science.gov (United States)

Heberle, Henry; Domingues, Romênia R.; Granato, Daniela C.; Yokoo, Sami; Canevarolo, Rafael R.; Winck, Flavia V.; Ribeiro, Ana Carolina P.; Brandão, Thaís Bianca; Filgueiras, Paulo R.; Cruz, Karen S. P.; Barbuto, José Alexandre; Poppi, Ronei J.; Minghim, Rosane; Telles, Guilherme P.; Fonseca, Felipe Paiva; Fox, Jay W.; Santos-Silva, Alan R.; Coletta, Ricardo D.; Sherman, Nicholas E.; Paes Leme, Adriana F.

2015-01-01

Targeted proteomics has flourished as the method of choice for prospecting for and validating potential candidate biomarkers in many diseases. However, challenges still remain due to the lack of standardized routines that can prioritize a limited number of proteins to be further validated in human samples. To help researchers identify candidate biomarkers that best characterize their samples under study, a well-designed integrative analysis pipeline, comprising MS-based discovery, feature selection methods, clustering techniques, bioinformatic analyses and targeted approaches was performed using discovery-based proteomic data from the secretomes of three classes of human cell lines (carcinoma, melanoma and non-cancerous). Three feature selection algorithms, namely, Beta-binomial, Nearest Shrunken Centroids (NSC), and Support Vector Machine-Recursive Features Elimination (SVM-RFE), indicated a panel of 137 candidate biomarkers for carcinoma and 271 for melanoma, which were differentially abundant between the tumor classes. We further tested the strength of the pipeline in selecting candidate biomarkers by immunoblotting, human tissue microarrays, label-free targeted MS and functional experiments. In conclusion, the proposed integrative analysis was able to pre-qualify and prioritize candidate biomarkers from discovery-based proteomics to targeted MS. PMID:26540631

Identification of cytotoxic drugs that selectively target tumor cells with MYC overexpression.

Directory of Open Access Journals (Sweden)

Anna Frenzel

Full Text Available Expression of MYC is deregulated in a wide range of human cancers, and is often associated with aggressive disease and poorly differentiated tumor cells. Identification of compounds with selectivity for cells overexpressing MYC would hence be beneficial for the treatment of these tumors. For this purpose we used cell lines with conditional MYCN or c-MYC expression, to screen a library of 80 conventional cytotoxic compounds for their ability to reduce tumor cell viability and/or growth in a MYC dependent way. We found that 25% of the studied compounds induced apoptosis and/or inhibited proliferation in a MYC-specific manner. The activities of the majority of these were enhanced both by c-MYC or MYCN over-expression. Interestingly, these compounds were acting on distinct cellular targets, including microtubules (paclitaxel, podophyllotoxin, vinblastine and topoisomerases (10-hydroxycamptothecin, camptothecin, daunorubicin, doxorubicin, etoposide as well as DNA, RNA and protein synthesis and turnover (anisomycin, aphidicholin, gliotoxin, MG132, methotrexate, mitomycin C. Our data indicate that MYC overexpression sensitizes cells to disruption of specific pathways and that in most cases c-MYC and MYCN overexpression have similar effects on the responses to cytotoxic compounds. Treatment of the cells with topoisomerase I inhibitors led to down-regulation of MYC protein levels, while doxorubicin and the small molecule MYRA-A was found to disrupt MYC-Max interaction. We conclude that the MYC pathway is only targeted by a subset of conventional cytotoxic drugs currently used in the clinic. Elucidating the mechanisms underlying their specificity towards MYC may be of importance for optimizing treatment of tumors with MYC deregulation. Our data also underscores that MYC is an attractive target for novel therapies and that cellular screenings of chemical libraries can be a powerful tool for identifying compounds with a desired biological activity.

The control of attentional target selection in a colour/colour conjunction task.

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Berggren, Nick; Eimer, Martin

2016-11-01

To investigate the time course of attentional object selection processes in visual search tasks where targets are defined by a combination of features from the same dimension, we measured the N2pc component as an electrophysiological marker of attentional object selection during colour/colour conjunction search. In Experiment 1, participants searched for targets defined by a combination of two colours, while ignoring distractor objects that matched only one of these colours. Reliable N2pc components were triggered by targets and also by partially matching distractors, even when these distractors were accompanied by a target in the same display. The target N2pc was initially equal in size to the sum of the two N2pc components to the two different types of partially matching distractors and became superadditive from approximately 250 ms after search display onset. Experiment 2 demonstrated that the superadditivity of the target N2pc was not due to a selective disengagement of attention from task-irrelevant partially matching distractors. These results indicate that attention was initially deployed separately and in parallel to all target-matching colours, before attentional allocation processes became sensitive to the presence of both matching colours within the same object. They suggest that attention can be controlled simultaneously and independently by multiple features from the same dimension and that feature-guided attentional selection processes operate in parallel for different target-matching objects in the visual field.

Tumor-targeted Nanobullets: Anti-EGFR nanobody-liposomes loaded with anti-IGF-1R kinase inhibitor for cancer treatment.

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van der Meel, Roy; Oliveira, Sabrina; Altintas, Isil; Haselberg, Rob; van der Veeken, Joris; Roovers, Rob C; van Bergen en Henegouwen, Paul M P; Storm, Gert; Hennink, Wim E; Schiffelers, Raymond M; Kok, Robbert J

2012-04-30

The epidermal growth factor receptor (EGFR) is a validated target for anti-cancer therapy and several EGFR inhibitors are used in the clinic. Over the years, an increasing number of studies have reported on the crosstalk between EGFR and other receptors that can contribute to accelerated cancer development or even acquisition of resistance to anti-EGFR therapies. Combined targeting of EGFR and insulin-like growth factor 1 receptor (IGF-1R) is a rational strategy to potentiate anti-cancer treatment and possibly retard resistance development. In the present study, we have pursued this by encapsulating the kinase inhibitor AG538 in anti-EGFR nanobody-liposomes. The thus developed dual-active nanobody-liposomes associated with EGFR-(over)expressing cells in an EGFR-specific manner and blocked both EGFR and IGF-1R activation, due to the presence of the EGFR-blocking nanobody EGa1 and the anti-IGF-1R kinase inhibitor AG538 respectively. AG538-loaded nanobody-liposomes induced a strong inhibition of tumor cell proliferation even upon short-term exposure followed by a drug-free wash-out period. Therefore, AG538-loaded nanobody-liposomes are a promising anti-cancer formulation due to efficient intracellular delivery of AG538 in combination with antagonistic and downregulating properties of the EGa1 nanobody-liposomes. Copyright © 2011 Elsevier B.V. All rights reserved.

Saururus cernuus lignans-Potent small molecule inhibitors of hypoxia-inducible factor-1

International Nuclear Information System (INIS)

Hossain, Chowdhury Faiz; Kim, Yong-Pil; Baerson, Scott R.; Zhang Lei; Bruick, Richard K.; Mohammed, Kaleem A.; Agarwal, Ameeta K.; Nagle, Dale G.; Zhou Yudong

2005-01-01

Hypoxia-inducible factor-1 (HIF-1) represents an important tumor-selective therapeutic target for solid tumors. In search of novel small molecule HIF-1 inhibitors, 5400 natural product-rich extracts from plants, marine organisms, and microbes were examined for HIF-1 inhibitory activities using a cell-based reporter assay. Bioassay-guided fractionation and isolation, followed by structure elucidation, yielded three potent natural product-derived HIF-1 inhibitors and two structurally related inactive compounds. In a T47D cell-based reporter assay, manassantin B 1 , manassantin A, and 4-O-methylsaucerneol inhibited hypoxia-induced HIF-1 activation with IC 50 values of 3, 3, and 20 nM, respectively. All three compounds are relatively hypoxia-specific inhibitors of HIF-1 activation, in comparison to other stimuli. The hypoxic induction of HIF-1 target genes CDKN1A, VEGF, and GLUT-1 were also inhibited. These compounds inhibit HIF-1 by blocking hypoxia-induced nuclear HIF-1α protein accumulation without affecting HIF-1α mRNA levels. In addition, preliminary structure-activity studies suggest specific structural requirements for this class of HIF-1 inhibitors

Discovery of aminofurazan-azabenzimidazoles as inhibitors of Rho-kinase with high kinase selectivity and antihypertensive activity.

Science.gov (United States)

Stavenger, Robert A; Cui, Haifeng; Dowdell, Sarah E; Franz, Robert G; Gaitanopoulos, Dimitri E; Goodman, Krista B; Hilfiker, Mark A; Ivy, Robert L; Leber, Jack D; Marino, Joseph P; Oh, Hye-Ja; Viet, Andrew Q; Xu, Weiwei; Ye, Guosen; Zhang, Daohua; Zhao, Yongdong; Jolivette, Larry J; Head, Martha S; Semus, Simon F; Elkins, Patricia A; Kirkpatrick, Robert B; Dul, Edward; Khandekar, Sanjay S; Yi, Tracey; Jung, David K; Wright, Lois L; Smith, Gary K; Behm, David J; Doe, Christopher P; Bentley, Ross; Chen, Zunxuan X; Hu, Erding; Lee, Dennis

2007-01-11

The discovery, proposed binding mode, and optimization of a novel class of Rho-kinase inhibitors are presented. Appropriate substitution on the 6-position of the azabenzimidazole core provided subnanomolar enzyme potency in vitro while dramatically improving selectivity over a panel of other kinases. Pharmacokinetic data was obtained for the most potent and selective examples and one (6n) has been shown to lower blood pressure in a rat model of hypertension.

Cytological profile of antibacterial FtsZ inhibitors and synthetic peptide MciZ

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Lidia Araujo-Bazan

2016-10-01

Full Text Available Cell division protein FtsZ is the organizer of the cytokinetic ring in almost all bacteria and a target for the discovery of new antibacterial agents that are needed to counter widespread antibiotic resistance. Bacterial cytological profiling, using quantitative microscopy, is a powerful approach for identifying the mechanism of action of antibacterial molecules affecting different cellular pathways. We have determined the cytological profile on Bacillus subtilis cells of a selection of small molecule inhibitors targeting FtsZ on different binding sites. FtsZ inhibitors lead to long undivided cells, impair the normal assembly of FtsZ into the midcell Z-rings, induce aberrant ring distributions, punctate FtsZ foci, membrane spots and also modify nucleoid length. Quantitative analysis of cell and nucleoid length combined, or the Z-ring distribution, allows categorizing FtsZ inhibitors and to distinguish them from antibiotics with other mechanisms of action, which should be useful for identifying new antibacterial FtsZ inhibitors. Biochemical assays of FtsZ polymerization and GTPase activity combined explain the cellular effects of the FtsZ polymer stabilizing agent PC190723 and its fragments. MciZ is a 40-aminoacid endogenous inhibitor of cell division normally expressed during sporulation in B. subtilis. Using FtsZ cytological profiling we have determined that exogenous synthetic MciZ is an effective inhibitor of B. subtilis cell division, Z-ring formation and localization. This finding supports our cell-based approach to screen for FtsZ inhibitors and opens new possibilities for peptide inhibitors of bacterial cell division.

Boro-norleucine as a P1 residue for the design of selective and potent DPP7 inhibitors.

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Shreder, Kevin R; Wong, Melissa S; Corral, Sergio; Yu, Zhizhou; Winn, David T; Wu, Min; Hu, Yi; Nomanbhoy, Tyzoon; Alemayehu, Senaiet; Fuller, Stacy R; Rosenblum, Jonathan S; Kozarich, John W

2005-10-01

Dipeptide-based inhibitors with C-substituted (alkyl or aminoalkyl) alpha-amino acids in the P2 position and boro-norleucine (boro-Nle) in the P1 position were synthesized. Relative to boro-proline, boro-Nle as a P1 residue was shown able to significantly dial out DPP4, FAP, DPP8, and DPP9 activity. Dab-boro-Nle (4g) proved to be the most selective and potent DPP7 inhibitor with a DPP7 IC50 value of 480 pM.

Histone deacetylase inhibitors improve the replication of oncolytic herpes simplex virus in breast cancer cells.

Directory of Open Access Journals (Sweden)

James J Cody

Full Text Available New therapies are needed for metastatic breast cancer patients. Oncolytic herpes simplex virus (oHSV is an exciting therapy being developed for use against aggressive tumors and established metastases. Although oHSV have been demonstrated safe in clinical trials, a lack of sufficient potency has slowed the clinical application of this approach. We utilized histone deacetylase (HDAC inhibitors, which have been noted to impair the innate antiviral response and improve gene transcription from viral vectors, to enhance the replication of oHSV in breast cancer cells. A panel of chemically diverse HDAC inhibitors were tested at three different doses (LD50 for their ability to modulate the replication of oHSV in breast cancer cells. Several of the tested HDAC inhibitors enhanced oHSV replication at low multiplicity of infection (MOI following pre-treatment of the metastatic breast cancer cell line MDA-MB-231 and the oHSV-resistant cell line 4T1, but not in the normal breast epithelial cell line MCF10A. Inhibitors of class I HDACs, including pan-selective compounds, were more effective for increasing oHSV replication compared to inhibitors that selectively target class II HDACs. These studies demonstrate that select HDAC inhibitors increase oHSV replication in breast cancer cells and provides support for pre-clinical evaluation of this combination strategy.

Integrated QSAR study for inhibitors of Hedgehog Signal Pathway against multiple cell lines:a collaborative filtering method.

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Gao, Jun; Che, Dongsheng; Zheng, Vincent W; Zhu, Ruixin; Liu, Qi

2012-07-31

The Hedgehog Signaling Pathway is one of signaling pathways that are very important to embryonic development. The participation of inhibitors in the Hedgehog Signal Pathway can control cell growth and death, and searching novel inhibitors to the functioning of the pathway are in a great demand. As the matter of fact, effective inhibitors could provide efficient therapies for a wide range of malignancies, and targeting such pathway in cells represents a promising new paradigm for cell growth and death control. Current research mainly focuses on the syntheses of the inhibitors of cyclopamine derivatives, which bind specifically to the Smo protein, and can be used for cancer therapy. While quantitatively structure-activity relationship (QSAR) studies have been performed for these compounds among different cell lines, none of them have achieved acceptable results in the prediction of activity values of new compounds. In this study, we proposed a novel collaborative QSAR model for inhibitors of the Hedgehog Signaling Pathway by integration the information from multiple cell lines. Such a model is expected to substantially improve the QSAR ability from single cell lines, and provide useful clues in developing clinically effective inhibitors and modifications of parent lead compounds for target on the Hedgehog Signaling Pathway. In this study, we have presented: (1) a collaborative QSAR model, which is used to integrate information among multiple cell lines to boost the QSAR results, rather than only a single cell line QSAR modeling. Our experiments have shown that the performance of our model is significantly better than single cell line QSAR methods; and (2) an efficient feature selection strategy under such collaborative environment, which can derive the commonly important features related to the entire given cell lines, while simultaneously showing their specific contributions to a specific cell-line. Based on feature selection results, we have proposed several

2-Arylbenzo[b]furan derivatives as potent human lipoxygenase inhibitors.

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Lang, Li; Dong, Ningning; Wu, Deyan; Yao, Xue; Lu, Weiqiang; Zhang, Chen; Ouyang, Ping; Zhu, Jin; Tang, Yun; Wang, Wei; Li, Jian; Huang, Jin

2016-01-01

Human lipoxygenases (LOXs) have been emerging as effective therapeutic targets for inflammatory diseases. In this study, we found that four natural 2-arylbenzo[b]furan derivatives isolated from Artocarpus heterophyllus exhibited potent inhibitory activities against human LOXs, including moracin C (1), artoindonesianin B-1 (2), moracin D (3), moracin M (4). In our in vitro experiments, compound 1 was identified as the most potent LOX inhibitor and the moderate subtype selective inhibitor of 12-LOX. Compounds 1 and 2 act as competitive inhibitors of LOXs. Moreover, 1 significantly inhibits LTB4 production and chemotactic capacity of neutrophils, and is capable of protecting vascular barrier from plasma leakage in vivo. In addition, the preliminary structure-activity relationship analysis was performed based on the above four naturally occurring (1-4) and six additional synthetic 2-arylbenzo[b]furan derivatives. Taken together, these 2-arylbenzo[b]furan derivatives, as LOXs inhibitors, could represent valuable leads for the future development of therapeutic agents for inflammatory diseases.

Selective serotonin reuptake inhibitor antidepressant use in first trimester pregnancy and risk of specific congenital anomalies

DEFF Research Database (Denmark)

Wemakor, Anthony; Casson, Karen; Garne, Ester

2015-01-01

Evidence of an association between early pregnancy exposure to selective serotonin reuptake inhibitors (SSRI) and congenital heart defects (CHD) has contributed to recommendations to weigh benefits and risks carefully. The objective of this study was to determine the specificity of association be...

Switching antidepressants after a first selective serotonin reuptake inhibitor in major depressive disorder: a systematic review

NARCIS (Netherlands)

Ruhé, Henricus G.; Huyser, Jochanan; Swinkels, Jan A.; Schene, Aart H.

2006-01-01

OBJECTIVE: Selective serotonin reuptake inhibitors (SSRIs) are frequently used as a first antidepressant for major depressive disorder but have response rates of 50% to 60% in daily practice. For patients with insufficient response to SSRIs, switching is often applied. This article aims to

Turning a Substrate Peptide into a Potent Inhibitor for the Histone Methyltransferase SETD8

Energy Technology Data Exchange (ETDEWEB)

Judge, Russell A.; Zhu, Haizhong; Upadhyay, Anup K.; Bodelle, Pierre M.; Hutchins, Charles W.; Torrent, Maricel; Marin, Violeta L.; Yu, Wenyu; Vedadi, Masoud; Li, Fengling; Brown, Peter J.; Pappano, William N.; Sun, Chaohong; Petros, Andrew M.

2016-12-08

SETD8 is a histone H4–K20 methyltransferase that plays an essential role in the maintenance of genomic integrity during mitosis and in DNA damage repair, making it an intriguing target for cancer research. While some small molecule inhibitors for SETD8 have been reported, the structural binding modes for these inhibitors have not been revealed. Using the complex structure of the substrate peptide bound to SETD8 as a starting point, different natural and unnatural amino acid substitutions were tested, and a potent (Ki 50 nM, IC50 0.33 μM) and selective norleucine containing peptide inhibitor has been obtained.

Allosteric inhibition enhances the efficacy of ABL kinase inhibitors to target unmutated BCR-ABL and BCR-ABL-T315I

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Mian Afsar

2012-09-01

Full Text Available Abstract Background Chronic myelogenous leukemia (CML and Philadelphia chromosome-positive (Ph+ acute lymphatic leukemia (Ph + ALL are caused by the t(9;22, which fuses BCR to ABL resulting in deregulated ABL-tyrosine kinase activity. The constitutively activated BCR/ABL-kinase “escapes” the auto-inhibition mechanisms of c-ABL, such as allosteric inhibition. The ABL-kinase inhibitors (AKIs Imatinib, Nilotinib or Dasatinib, which target the ATP-binding site, are effective in Ph + leukemia. Another molecular therapy approach targeting BCR/ABL restores allosteric inhibition. Given the fact that all AKIs fail to inhibit BCR/ABL harboring the ‘gatekeeper’ mutation T315I, we investigated the effects of AKIs in combination with the allosteric inhibitor GNF2 in Ph + leukemia. Methods The efficacy of this approach on the leukemogenic potential of BCR/ABL was studied in Ba/F3 cells, primary murine bone marrow cells, and untransformed Rat-1 fibroblasts expressing BCR/ABL or BCR/ABL-T315I as well as in patient-derived long-term cultures (PDLTC from Ph + ALL-patients. Results Here, we show that GNF-2 increased the effects of AKIs on unmutated BCR/ABL. Interestingly, the combination of Dasatinib and GNF-2 overcame resistance of BCR/ABL-T315I in all models used in a synergistic manner. Conclusions Our observations establish a new approach for the molecular targeting of BCR/ABL and its resistant mutants using a combination of AKIs and allosteric inhibitors.

Target Selection Models with Preference Variation Between Offenders

NARCIS (Netherlands)

Townsley, Michael; Birks, Daniel; Ruiter, Stijn; Bernasco, Wim; White, Gentry

2016-01-01

Objectives: This study explores preference variation in location choice strategies of residential burglars. Applying a model of offender target selection that is grounded in assertions of the routine activity approach, rational choice perspective, crime pattern and social disorganization theories,

The modulation of radiosensitivity by combined treatment of selective COX-2 inhibitor, NS 398 and EGF receptor blocker AG 1478 in HeLa cell line

International Nuclear Information System (INIS)

Youn, Seon Min; Oh, Young Kee; Kim, Joo Heon; Park, Mi Ja; Seong, In Ock; Kang, Ki Mun; Chai, Gyu Yong

2005-01-01

Selective inhibition of multiple molecular targets may improve the antitumor activity of radiation. Two specific inhibitors of selective cyclooxygenase-2 (COX-2) and epidermal growth factor receptor (EGFR) were combined with radiation on the HeLa cell line. To investigate cooperative mechanism with selective COX-2 inhibitor and EGFR blocker, in vitro experiments were done. Antitumor effect was obtained by growth inhibition and apoptosis analysis by annexin V-Flous method. Radiation modulation effects were determined by the clonogenic cell survival assay. Surviving fractions at 2 Gy (SF 2 ) and dose enhancement radio at a surviving fraction of 0.25 were evaluated. To investigate the mechanism of the modulation of radiosensitivity, the cell cycle analyses were done by flow cytometry. The bcl-2 and bax expressions were analyzed by western blot. A cooperative effect were observed on the apoptosis of the HeLa cell line when combination of the two drugs, AG 1478 and NS 398 with radiation at the lowest doses, apoptosis of 22.70% compare with combination of the one drug with radiation, apoptosis of 8.49%. In cell cycle analysis, accumulation of cell on G 0 /G 1 phase and decrement of S phase fraction was observed from 24 hours to 72 hours after treatment with radiation, AG 1478 and NS 398. The combination of NS 398 and AG 1478 enhanced radiosensitivity in a concentration-dependent manner in HeLa cells with dose enhancement ratios of 3.00 and SF 2 of 0.12 but the combination of one drug with radiation was not enhanced radiosensitivity with dose enhancement ratios of 1.12 and SF2 of 0.68 (ρ = 0.005). The expression levels of bcl-2 and bax were reduced when combined with AG 1478 and NS 398. Our results indicate that the selective COX-2 inhibitor and EGFR blocker combined with radiation have potential additive or cooperative effects on radiation treatment and may act through various mechanisms including direct inhibition of tumor cell proliferation, suppression of tumor cell

Molecular Targeted Agents for Gastric Cancer: A Step Forward Towards Personalized Therapy

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Tom Geldart

2013-01-01

Full Text Available Gastric cancer (GC represents a major cancer burden worldwide, and remains the second leading cause of cancer-related death. Due to its insidious nature, presentation is usually late and often carries a poor prognosis. Despite having improved treatment modalities over the last decade, for most patients only modest improvements have been seen in overall survival. Recent progress in understanding the molecular biology of GC and its signaling pathways, offers the hope of clinically significant promising advances for selected groups of patients. Patients with Her-2 overexpression or amplification have experienced benefit from the integration of monoclonal antibodies such as trastuzumab to the standard chemotherapy. Additionally, drugs targeting angiogenesis (bevacizumab, sorafenib, sunitinib are under investigation and other targeted agents such as mTOR inhibitors, anti c-MET, polo-like kinase 1 inhibitors are in preclinical or early clinical development. Patient selection and the development of reliable biomarkers to accurately select patients most likely to benefit from these tailored therapies is now key. Future trials should focus on these advances to optimize the treatment for GC patients. This article will review recent progress and current status of targeted agents in GC.

Sequence-selective targeting of duplex DNA by peptide nucleic acids

DEFF Research Database (Denmark)

Nielsen, Peter E

2010-01-01

Sequence-selective gene targeting constitutes an attractive drug-discovery approach for genetic therapy, with the aim of reducing or enhancing the activity of specific genes at the transcriptional level, or as part of a methodology for targeted gene repair. The pseudopeptide DNA mimic peptide...

Pharmacological targeting of CDK9 in cardiac hypertrophy.

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Krystof, Vladimír; Chamrád, Ivo; Jorda, Radek; Kohoutek, Jirí

2010-07-01

Cardiac hypertrophy allows the heart to adapt to workload, but persistent or unphysiological stimulus can result in pump failure. Cardiac hypertrophy is characterized by an increase in the size of differentiated cardiac myocytes. At the molecular level, growth of cells is linked to intensive transcription and translation. Several cyclin-dependent kinases (CDKs) have been identified as principal regulators of transcription, and among these CDK9 is directly associated with cardiac hypertrophy. CDK9 phosphorylates the C-terminal domain of RNA polymerase II and thus stimulates the elongation phase of transcription. Chronic activation of CDK9 causes not only cardiac myocyte enlargement but also confers predisposition to heart failure. Due to the long interest of molecular oncologists and medicinal chemists in CDKs as potential targets of anticancer drugs, a portfolio of small-molecule inhibitors of CDK9 is available. Recent determination of CDK9's crystal structure now allows the development of selective inhibitors and their further optimization in terms of biochemical potency and selectivity. CDK9 may therefore constitute a novel target for drugs against cardiac hypertrophy.

Targeting GRP75 improves HSP90 inhibitor efficacy by enhancing p53-mediated apoptosis in hepatocellular carcinoma.

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Weiwei Guo

Full Text Available Heat shock protein 90 (HSP90 inhibitors are potential drugs for cancer therapy. The inhibition of HSP90 on cancer cell growth largely through degrading client proteins, like Akt and p53, therefore, triggering cancer cell apoptosis. Here, we show that the HSP90 inhibitor 17-AAG can induce the expression of GRP75, a member of heat shock protein 70 (HSP70 family, which, in turn, attenuates the anti-growth effect of HSP90 inhibition on cancer cells. Additionally, 17-AAG enhanced binding of GRP75 and p53, resulting in the retention of p53 in the cytoplasm. Blocking GRP75 with its inhibitor MKT-077 potentiated the anti-tumor effects of 17-AAG by disrupting the formation of GRP75-p53 complexes, thereby facilitating translocation of p53 into the nuclei and leading to the induction of apoptosis-related genes. Finally, dual inhibition of HSP90 and GRP75 was found to significantly inhibit tumor growth in a liver cancer xenograft model. In conclusion, the GRP75 inhibitor MKT-077 enhances 17-AAG-induced apoptosis in HCCs and increases p53-mediated inhibition of tumor growth in vivo. Dual targeting of GRP75 and HSP90 may be a useful strategy for the treatment of HCCs.

Discovery and Biological Evaluation of a Series of Pyrrolo[2,3-b]pyrazines as Novel FGFR Inhibitors.

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Zhang, Yan; Liu, Hongchun; Zhang, Zhen; Wang, Ruifeng; Liu, Tongchao; Wang, Chaoyun; Ma, Yuchi; Ai, Jing; Zhao, Dongmei; Shen, Jingkang; Xiong, Bing

2017-04-05

Abnormality of fibroblast growth factor receptor (FGFR)-mediated signaling pathways were frequently found in various human malignancies, making FGFRs hot targets for cancer treatment. To address the consistent need for a new chemotype of FGFR inhibitors, here, we started with a hit structure identified from our internal hepatocyte growth factor receptor (also called c-Met) inhibitor project, and conducted a chemical optimization. After exploring three parts of the hit compound, we finally discovered a new series of pyrrolo[2,3- b ]pyrazine FGFR inhibitors, which contain a novel scaffold and unique molecular shape. We believe that our findings can help others to further develop selective FGFR inhibitors.

Discovery and Biological Evaluation of a Series of Pyrrolo[2,3-b]pyrazines as Novel FGFR Inhibitors

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Yan Zhang

2017-04-01

Full Text Available Abnormality of fibroblast growth factor receptor (FGFR-mediated signaling pathways were frequently found in various human malignancies, making FGFRs hot targets for cancer treatment. To address the consistent need for a new chemotype of FGFR inhibitors, here, we started with a hit structure identified from our internal hepatocyte growth factor receptor (also called c-Met inhibitor project, and conducted a chemical optimization. After exploring three parts of the hit compound, we finally discovered a new series of pyrrolo[2,3-b]pyrazine FGFR inhibitors, which contain a novel scaffold and unique molecular shape. We believe that our findings can help others to further develop selective FGFR inhibitors.

COMPARISON OF SELECTIVE AND NON SELECTIVE CYCLO-OXYGENASE 2 INHIBITORS IN EXPERIMENTAL COLITIS EXACERBATION: role of leukotriene B4 and superoxide dismutase

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José Wander BREGANÓ

2014-09-01

Full Text Available Context Nonsteroidal anti-inflammatory drugs are considered one of the most important causes of reactivation of inflammatory bowel disease. With regard to selective cyclo-oxygenase 2 inhibitors, the results are controversial in experimental colitis as well as in human studies. Objectives The aim this study is to compare nonsteroidal anti-inflammatory drugs effects, selective and non selective cyclo-oxygenase 2 inhibitors, in experimental colitis and contribute to the understanding of the mechanisms which nonsteroidal anti-inflammatory drugs provoke colitis exacerbation. Methods Six groups of rats: without colitis, with colitis, and colitis treated with celecoxib, ketoprofen, indometacin or diclofenac. Survival rates, hemoglobin, plasmatic albumin, colonic tissue of interleukin-1ß, interleukin-6, tumor necrosis factor alpha, prostaglandin E2, catalase, superoxide dismutase, thiobarbituric acid-reactive substances, chemiluminescence induced by tert-butil hydroperoxides, and tissue and plasmatic leukotriene B4 were determined. Results The groups treated with diclofenac or indometacin presented lower survival rates, hemoglobin and albumin, higher tissue and plasmatic leukotriene B4 and tissue superoxide dismutase than the group treated with celecoxib. Ketoprofen presented an intermediary behavior between diclofenac/indometacin and celecoxib, concerning to survival rate and albumin. The groups without colitis, with colitis and with colitis treated with celecoxib showed leukotriene B4 and superoxide dismutase lower levels than the groups treated with nonselective cyclo-oxygenase 2 inhibitors. Conclusions Diclofenac and indometacin presented the highest degree of induced colitis exacerbation with nonsteroidal anti-inflammatory drugs, celecoxib did not show colitis exacerbation, and ketoprofen presented an intermediary behavior between diclofenac/indometacin and celecoxib. These results suggest that leukotriene B4 and superoxide dismutase can be

In silico search of energy metabolism inhibitors for alternative leishmaniasis treatments.

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Silva, Lourival A; Vinaud, Marina C; Castro, Ana Maria; Cravo, Pedro Vítor L; Bezerra, José Clecildo B

2015-01-01

Leishmaniasis is a complex disease that affects mammals and is caused by approximately 20 distinct protozoa from the genus Leishmania. Leishmaniasis is an endemic disease that exerts a large socioeconomic impact on poor and developing countries. The current treatment for leishmaniasis is complex, expensive, and poorly efficacious. Thus, there is an urgent need to develop more selective, less expensive new drugs. The energy metabolism pathways of Leishmania include several interesting targets for specific inhibitors. In the present study, we sought to establish which energy metabolism enzymes in Leishmania could be targets for inhibitors that have already been approved for the treatment of other diseases. We were able to identify 94 genes and 93 Leishmania energy metabolism targets. Using each gene's designation as a search criterion in the TriTrypDB database, we located the predicted peptide sequences, which in turn were used to interrogate the DrugBank, Therapeutic Target Database (TTD), and PubChem databases. We identified 44 putative targets of which 11 are predicted to be amenable to inhibition by drugs which have already been approved for use in humans for 11 of these targets. We propose that these drugs should be experimentally tested and potentially used in the treatment of leishmaniasis.

A calpain-2 selective inhibitor enhances learning & memory by prolonging ERK activation.