Towards precision medicine-based therapies for glioblastoma: interrogating human disease genomics and mouse phenotypes.

BMC Genomics. 2016;17(Suppl 7):516

Authors: Chen Y, Gao Z, Wang B, Xu R

Abstract
BACKGROUND: Glioblastoma (GBM) is the most common and aggressive brain tumors. It has poor prognosis even with optimal radio- and chemo-therapies. Since GBM is highly heterogeneous, drugs that target on specific molecular profiles of individual tumors may achieve maximized efficacy. Currently, the Cancer Genome Atlas (TCGA) projects have identified hundreds of GBM-associated genes. We develop a drug repositioning approach combining disease genomics and mouse phenotype data towards predicting targeted therapies for GBM.
METHODS: We first identified disease specific mouse phenotypes using the most recently discovered GBM genes. Then we systematically searched all FDA-approved drugs for candidates that share similar mouse phenotype profiles with GBM. We evaluated the ranks for approved and novel GBM drugs, and compared with an existing approach, which also use the mouse phenotype data but not the disease genomics data.
RESULTS: We achieved significantly higher ranks for the approved and novel GBM drugs than the earlier approach. For all positive examples of GBM drugs, we achieved a median rank of 9.2 45.6 of the top predictions have been demonstrated effective in inhibiting the growth of human GBM cells.
CONCLUSION: We developed a computational drug repositioning approach based on both genomic and phenotypic data. Our approach prioritized existing GBM drugs and outperformed a recent approach. Overall, our approach shows potential in discovering new targeted therapies for GBM.

PMID: 27557118 [PubMed - as supplied by publisher]

EDITORIAL: Repurposing Niacin as Antiplatelet Drug?

Curr Clin Pharmacol. 2016;11(1):2-3

Authors: Mangoni AA

PMID: 26860693 [PubMed - indexed for MEDLINE]

Oral treatments of Echinococcus multilocularis-infected mice with the antimalarial drug mefloquine that potentially interacts with parasite ferritin and cystatin.

Int J Antimicrob Agents. 2015 Nov;46(5):546-51

Authors: Küster T, Stadelmann B, Rufener R, Risch C, Müller J, Hemphill A

Abstract
This study investigated the effects of oral treatments of Echinococcus multilocularis-infected mice with the antimalarial drug mefloquine (MEF) and identified proteins that bind to MEF in parasite extracts and human cells by affinity chromatography. In a pilot experiment, MEF treatment was applied 5 days per week and was intensified by increasing the dosage stepwise from 12.5 mg/kg to 200 mg/kg during 4 weeks followed by treatments of 100 mg/kg during the last 7 weeks. This resulted in a highly significant reduction of parasite weight in MEF-treated mice compared with mock-treated mice, but the reduction was significantly less efficacious compared with the standard treatment regimen of albendazole (ABZ). In a second experiment, MEF was applied orally in three different treatment groups at dosages of 25, 50 or 100 mg/kg, but only twice a week, for a period of 12 weeks. Treatment at 100 mg/kg had a profound impact on the parasite, similar to ABZ treatment at 200 mg/kg/day (5 days/week for 12 weeks). No adverse side effects were noted. To identify proteins in E. multilocularis metacestodes that physically interact with MEF, affinity chromatography of metacestode extracts was performed on MEF coupled to epoxy-activated Sepharose(®), followed by SDS-PAGE and in-gel digestion LC-MS/MS. This resulted in the identification of E. multilocularis ferritin and cystatin as MEF-binding proteins. In contrast, when human cells were exposed to MEF affinity chromatography, nicotinamide phosphoribosyltransferase was identified as a MEF-binding protein. This indicates that MEF could potentially interact with different proteins in parasites and human cells.

PMID: 26395219 [PubMed - indexed for MEDLINE]

Repositioning Antitubercular 6-Nitro-2,3-dihydroimidazo[2,1-b][1,3]oxazoles for Neglected Tropical Diseases: Structure-Activity Studies on a Preclinical Candidate for Visceral Leishmaniasis.

J Med Chem. 2016 Mar 24;59(6):2530-50

Authors: Thompson AM, O'Connor PD, Blaser A, Yardley V, Maes L, Gupta S, Launay D, Martin D, Franzblau SG, Wan B, Wang Y, Ma Z, Denny WA

Abstract
6-Nitro-2,3-dihydroimidazo[2,1-b][1,3]oxazole derivatives were initially studied for tuberculosis within a backup program for the clinical trial agent pretomanid (PA-824). Phenotypic screening of representative examples against kinetoplastid diseases unexpectedly led to the identification of DNDI-VL-2098 as a potential first-in-class drug candidate for visceral leishmaniasis (VL). Additional work was then conducted to delineate its essential structural features, aiming to improve solubility and safety without compromising activity against VL. While the 4-nitroimidazole portion was specifically required, several modifications to the aryloxy side chain were well-tolerated e.g., exchange of the linking oxygen for nitrogen (or piperazine), biaryl extension, and replacement of phenyl rings by pyridine. Several less lipophilic analogues displayed improved aqueous solubility, particularly at low pH, although stability toward liver microsomes was highly variable. Upon evaluation in a mouse model of acute Leishmania donovani infection, one phenylpyridine derivative (37) stood out, providing efficacy surpassing that of the original preclinical lead.

PMID: 26901446 [PubMed - indexed for MEDLINE]

Repurposing Registered Drugs as Antagonists for Protease-Activated Receptor 2.

J Chem Inf Model. 2015 Oct 26;55(10):2079-84

Authors: Xu W, Lim J, Goh CY, Suen JY, Jiang Y, Yau MK, Wu KC, Liu L, Fairlie DP

Abstract
Virtual screening of a drug database identified Carvedilol, Loratadine, Nefazodone and Astemizole as PAR2 antagonists, after ligand docking and molecular dynamics simulations using a PAR2 homology model and a putative binding mode of a known PAR2 ligand. The drugs demonstrated competitive binding and antagonism of calcium mobilization and ERK1/2 phosphorylation in CHO-hPAR2 transfected cells, while inhibiting IL-6 secretion in PAR2 expressing MDA-MB-231 breast cancer cells. This research highlights opportunities for GPCR hit-finding from FDA-approved drugs.

PMID: 26445028 [PubMed - indexed for MEDLINE]

Fighting viruses with antibiotics: an overlooked path.

Int J Antimicrob Agents. 2016 Aug 5;

Authors: Colson P, Raoult D

PMID: 27546219 [PubMed - as supplied by publisher]

The antifungal compound butenafine eliminates promastigote and amastigote forms of Leishmania (Leishmania) amazonensis and Leishmania (Viannia) braziliensis.

Parasitol Int. 2016 Aug 18;

Authors: Bezerra-Souza A, Yamamoto ES, Laurenti MD, Ribeiro SP, Passero LF

Abstract
The production of ergosterol lipid, important for the Leishmania membrane homeostasis, involves different enzymes. This pathway can be blocked to azoles and allylamines drugs, such as Butenafine. The aim of the present work was to evaluate the anti-leishmanicidal activity of this drug in 2 major species of Leishmania responsible for causing the American tegumentar leishmaniasis (L. (L.) amazonensis and L. (V.) braziliensis). Butenafine eliminated promastigote forms of L. amazonensis and L. braziliensis with efficacy similar to miltefosine, a standard anti-leishmania drug. In addition, butenafine induced alterations in promastigote forms of L. amazonensis that resemble programmed cell death. Butenafine as well as miltefosine presented mild toxicity in peritoneal macrophages, however, butenafine was more effective to eliminate intracellular amastigotes of both L. amazonensis and L. braziliensis, and this effect was not associated with elevated levels of nitric oxide or hydrogen peroxide. Taken together, data presented herein suggests that butenafine can be considered as a prototype drug able to eliminate L. amazonensis and L. braziliensis, etiological agents of anergic diffuse and mucocutaneous leishmaniasis, respectively.

PMID: 27546158 [PubMed - as supplied by publisher]

Repositioning of Endonuclear Receptors Binders as Potential Antibacterial and Antifungal Agents. Eptyloxìm: A Potential and Novel Gyrase B and Cytochrome Cyp51 Inhibitor.

Mol Inform. 2016 Sep;35(8-9):326-32

Authors: Carrieri A, L'Abbate M, Di Chicco M, Rosato A, Carbonara G, Fracchiolla G

Abstract
A novel class of antibacterial and antifungal agents is here identified by means of dockings and virtual screening techniques. Biological data proved the initial effort, formulated on the structure similarity of nuclear receptors binders with known quinolones or thiazole derivatives, to reposition PPARs agonists as likely bacterial type II topoisomerases inhibitors.

PMID: 27546036 [PubMed - in process]

Chloroquine: An Old Drug with New Perspective Against Giardiasis.

Recent Pat Antiinfect Drug Discov. 2015;10(2):134-41

Authors: Escobedo AA, Almirall P, Cimerman S, Lalle M, Pacheco F, Acanda CZ, Sánchez N

Abstract
The occurrence of treatment failures to first-line treatment for giardiasis, one of the most widespread although neglected parasitic disease, has long been recognised. Nowadays, it starts to represent a great challenge to clinicians, especially in endemic countries. This requires the introduction of new drug interventions, but the development of novel drugs is a time and money consuming effort with most of the compounds never reaching the market. Consequently, alternative strategies are needed, especially for the treatment of giardiasis. Chloroquine (CQ), a synthetic drug developed as antimalarial agent, has been shown to also exert antigiardial activity. Here, we present a mini-research summarizing results on the treatment of human clinical cases with CQ, going through in vitro research, case report, and case series to human clinical trials, highlighting the benefits and mentioning possible adverse effects.

PMID: 26365362 [PubMed - indexed for MEDLINE]

Computational drugs repositioning identifies inhibitors of oncogenic PI3K/AKT/P70S6K-dependent pathways among FDA-approved compounds.

Oncotarget. 2016 Aug 16;

Authors: Carrella D, Manni I, Tumaini B, Dattilo R, Papaccio F, Mutarelli M, Sirci F, Amoreo CA, Mottolese M, Iezzi M, Ciolli L, Aria V, Bosotti R, Isacchi A, Loreni F, Bardelli A, Avvedimento VE, di Bernardo D, Cardone L

Abstract
The discovery of inhibitors for oncogenic signalling pathways remains a key focus in modern oncology, based on personalized and targeted therapeutics. Computational drug repurposing via the analysis of FDA-approved drug network is becoming a very effective approach to identify therapeutic opportunities in cancer and other human diseases. Given that gene expression signatures can be associated with specific oncogenic mutations, we tested whether a "reverse" oncogene-specific signature might assist in the computational repositioning of inhibitors of oncogenic pathways. As a proof of principle, we focused on oncogenic PI3K-dependent signalling, a molecular pathway frequently driving cancer progression as well as raising resistance to anticancer-targeted therapies. We show that implementation of "reverse" oncogenic PI3K-dependent transcriptional signatures combined with interrogation of drug networks identified inhibitors of PI3K-dependent signalling among FDA-approved compounds. This led to repositioning of Niclosamide (Niclo) and Pyrvinium Pamoate (PP), two anthelmintic drugs, as inhibitors of oncogenic PI3K-dependent signalling. Niclo inhibited phosphorylation of P70S6K, while PP inhibited phosphorylation of AKT and P70S6K, which are downstream targets of PI3K. Anthelmintics inhibited oncogenic PI3K-dependent gene expression and showed a cytostatic effect in vitro and in mouse mammary gland. Lastly, PP inhibited the growth of breast cancer cells harbouring PI3K mutations. Our data indicate that drug repositioning by network analysis of oncogene-specific transcriptional signatures is an efficient strategy for identifying oncogenic pathway inhibitors among FDA-approved compounds. We propose that PP and Niclo should be further investigated as potential therapeutics for the treatment of tumors or diseases carrying the constitutive activation of the PI3K/P70S6K signalling axis.

PMID: 27542212 [PubMed - as supplied by publisher]

Stem Cell Hydrogel, Jump-Starting Zika Drug Discovery, and Engineering RNA Recognition.

Cell Chem Biol. 2016 Aug 18;23(8):885-886

Authors: Kostic M

Abstract
Every month the editors of Cell Chemical Biology bring you highlights of the most recent chemical biology literature that impressed them with creativity and potential for follow up work. Our August 2016 selection includes a description of hydrogels with self-tunable stiffness that are used to profile lipid metabolites during stems cell differentiation, a look at whether we can find a drug repurposing solution to Zika virus infection, and an engineered RNA recognition motif (RRM).

PMID: 27541191 [PubMed - as supplied by publisher]

Bazedoxifene as a Novel GP130 Inhibitor for Pancreatic Cancer Therapy.

Mol Cancer Ther. 2016 Aug 17;

Authors: Wu X, Cao Y, Xiao H, Li C, Lin J

Abstract
The IL-6/GP130/STAT3 pathway is crucial for tumorigenesis in multiple cancer types, including pancreatic cancer and presents as a viable target for cancer therapy. We reported Bazedoxifene, which is approved as a selective estrogen modulator by FDA, as a novel inhibitor of IL-6/GP130 protein-protein interactions using multiple ligand simultaneous docking and drug repositioning approaches. STAT3 is one of the major downstream effectors of IL-6/GP130. Here, we observed Bazedoxifene inhibited STAT3 phosphorylation and STAT3 DNA binding, induced apoptosis, and suppressed tumor growth in pancreatic cancer cells with persistent IL-6/GP130/STAT3 signaling in vitro and in vivo. In addition, IL-6 but not INF-γ rescued Bazedoxifene-mediated reduction of cell viability. Bazedoxifene also inhibited STAT3 phosphorylation induced by IL-6 and IL-11, but not by OSM or STAT1 phosphorylation induced by INF-γ in pancreatic cancer cells, suggesting that Bazedoxifene inhibits GP130/STAT3 pathway mediated by IL-6 and IL-11. Furthermore, Bazedoxifene combined with paclitaxel or gemcitabine synergistically inhibited cell viability and cell migration in pancreatic cancer cells. These results indicate that Bazedoxifene is a potential agent and can generate synergism when combined with conventional chemotherapy in human pancreatic cancer cells and tumor Xenograft in mice. Therefore, our results support that Bazedoxifene as a novel inhibitor of GP130 signaling and may be a potential and safe therapeutic agent for human pancreatic cancer therapy.

PMID: 27535971 [PubMed - as supplied by publisher]

PPARγ agonists promote differentiation of cancer stem cells by restraining YAP transcriptional activity.

Oncotarget. 2016 Aug 12;

Authors: Basu-Roy U, Han E, Rattanakorn K, Gadi A, Verma N, Maurizi G, Gunaratne PH, Coarfa C, Kennedy OD, Garabedian MJ, Basilico C, Mansukhani A

Abstract
Osteosarcoma (OS) is a highly aggressive pediatric bone cancer in which most tumor cells remain immature and fail to differentiate into bone-forming osteoblasts. However, OS cells readily respond to adipogenic stimuli suggesting they retain mesenchymal stem cell-like properties. Here we demonstrate that nuclear receptor PPARγ agonists such as the anti-diabetic, thiazolidinedione (TZD) drugs induce growth arrest and cause adipogenic differentiation in human, mouse and canine OS cells as well as in tumors in mice. Gene expression analysis reveals that TZDs induce lipid metabolism pathways while suppressing targets of the Hippo-YAP pathway, Wnt signaling and cancer-related proliferation pathways. Significantly, TZD action appears to be restricted to the high Sox2 expressing cancer stem cell population and is dependent on PPARγ expression. TZDs also affect growth and cell fate by causing the cytoplasmic sequestration of the transcription factors SOX2 and YAP that are required for tumorigenicity. Finally, we identify a TZD-regulated gene signature based on Wnt/Hippo target genes and PPARγ that predicts patient outcomes. Together, this work highlights a novel connection between PPARγ agonist in inducing adipogenesis and mimicking the tumor suppressive hippo pathway. It also illustrates the potential of drug repurposing for TZD-based differentiation therapy for osteosarcoma.

PMID: 27528232 [PubMed - as supplied by publisher]

Repositioning antipsychotic chlorpromazine for treating colorectal cancer by inhibiting sirtuin 1.

Oncotarget. 2015 Sep 29;6(29):27580-95

Authors: Lee WY, Lee WT, Cheng CH, Chen KC, Chou CM, Chung CH, Sun MS, Cheng HW, Ho MN, Lin CW

Abstract
Investigating existing drugs for repositioning can enable overcoming bottlenecks in the drug development process. Here, we investigated the effect and molecular mechanism of the antipsychotic drug chlorpromazine (CPZ) and identified its potential for treating colorectal cancer (CRC). Human CRC cell lines harboring different p53 statuses were used to investigate the inhibitory mechanism of CPZ. CPZ effectively inhibited tumor growth and induced apoptosis in CRC cells in a p53-dependent manner. Activation of c-jun N-terminal kinase (JNK) was crucial for CPZ-induced p53 expression and the subsequent induction of tumor apoptosis. Induction of p53 acetylation at lysine382 was involved in CPZ-mediated tumor apoptosis, and this induction was attenuated by sirtuin 1 (SIRT1), a class III histone deacetylase. By contrast, knocking down SIRT1 sensitized tumor cells to CPZ treatment. Moreover, CPZ induced the degradation of SIRT1 protein participating downstream of JNK, and JNK suppression abrogated CPZ-mediated SIRT1 downregulation. Clinical analysis revealed a significant association between high SIRT1 expression and poor outcome in CRC patients. These data suggest that SIRT1 is an attractive therapeutic target for CRC and that CPZ is a potential repositioned drug for treating CRC.

PMID: 26363315 [PubMed - indexed for MEDLINE]

Pharmacodynamics and Systems Pharmacology Approaches to Repurposing Drugs in the Wake of Global Health Burden.

J Pharm Sci. 2016 Aug 11;

Authors: Bai JP

Abstract
There are emergent needs for cost-effective treatment worldwide, for which repurposing to develop a drug with existing marketing approval of disease(s) for new disease(s) is a valid option. Although strategic mining of electronic health records has produced real-world evidences to inform drug repurposing, using omics data (drug and disease), knowledge base of protein interactions, and database of transcription factors have been explored. Structured integration of all the existing data under the framework of drug repurposing will facilitate decision making. The ability to foresee the need to integrate new data types produced by emergent technologies and to enable data connectivity in the context of human biology and targeted diseases, as well as to use the existing crucial quality data of all approved drugs will catapult the number of drugs being successfully repurposed. However, translational pharmacodynamics databases for modeling information across human biology in the context of host factors are lacking and are critically needed for drug repurposing to improve global public health, especially for the efforts to combat neglected tropic diseases as well as emergent infectious diseases such as Zika or Ebola virus.

PMID: 27522921 [PubMed - as supplied by publisher]

Poly lactic-co-glycolic acid controlled delivery of Disulfiram to target liver cancer stem-like cells.

Nanomedicine. 2016 Aug 10;

Authors: Wang Z, Tan J, McConville C, Kannappan V, Tawari PE, Brown J, Ding J, Armesilla AL, Irache JM, Mei QB, Tan Y, Liu Y, Jiang W, Bian X, Wang W

Abstract
Disulfiram (DS), an anti-alcoholism drug, shows very strong cytotoxicity in many cancer types. However its clinical application in cancer treatment is limited by the very short half-life in the bloodstream. In this study, we developed a poly lactic-co-glycolic acid (PLGA)-encapsulated DS protecting DS from the degradation in the bloodstream. The newly developed DS-PLGA was characterized. The DS-PLGA has very satisfactory encapsulation efficiency, drug-loading content and controlled release rate in vitro. PLGA encapsulation extended the half-life of DS from shorter than 2minutes to 7hours in serum. In combination with copper, DS-PLGA significantly inhibited the liver cancer stem cell population. CI-isobologram showed a remarkable synergistic cytotoxicity between DS-PLGA and 5-FU or Sorafenib. It also demonstrated very promising anticancer efficacy and antimetastatic effect in liver cancer mouse model. Both DS and PLGA are FDA approved products for clinical application. Our study may lead to repositioning of DS into liver cancer treatment.

PMID: 27521693 [PubMed - as supplied by publisher]

Connection Map for Compounds (CMC): A Server for Combinatorial Drug Toxicity and Efficacy Analysis.

J Chem Inf Model. 2016 Aug 10;

Authors: Liu L, Tsompana M, Wang Y, Wu D, Zhu L, Zhu R

Abstract
Drug discovery and development is a costly and time-consuming process with a high risk for failure resulting primarily from a drug's associated clinical safety and efficacy potential. Identifying and eliminating inapt candidate drugs as early as possible is an effective way for reducing unnecessary costs, but limited analytical tools are currently available for this purpose. Recent growth in the area of toxicogenomics and pharmacogenomics has provided with a vast amount of drug expression microarray data. Web servers such as CMap and LTMap have used this information to evaluate drug toxicity and mechanisms of action independently, however their wider applicability has been limited by the lack of a combinatorial drug-safety type of analysis. Using available genome-wide drug transcriptional expression profiles, we developed the first web server for combinatorial evaluation of toxicity and efficacy of candidate drugs named "Connection Map for Compounds" (CMC). Using CMC, researchers can initially compare their query drug gene signatures with prebuilt gene profiles generated from two large-scale toxicogenomics databases, and subsequently perform a drug efficacy analysis for identification of known mechanisms of drug action or generation of new predictions. CMC provides a novel approach for drug repositioning and early evaluation in drug discovery with its unique combination of toxicity and efficacy analyses, expansibility of data and algorithms, and customization of reference gene profiles. CMC can be freely accessed at http://cadd.tongji.edu.cn/webserver/CMCbp.jsp.

PMID: 27508329 [PubMed - as supplied by publisher]

Identification of Trypanocidal Activity for Known Clinical Compounds Using a New Trypanosoma cruzi Hit-Discovery Screening Cascade.

PLoS Negl Trop Dis. 2016 Apr;10(4):e0004584

Authors: De Rycker M, Thomas J, Riley J, Brough SJ, Miles TJ, Gray DW

Abstract
Chagas disease is a significant health problem in Latin America and the available treatments have significant issues in terms of toxicity and efficacy. There is thus an urgent need to develop new treatments either via a repurposing strategy or through the development of new chemical entities. A key first step is the identification of compounds with anti-Trypanosoma cruzi activity from compound libraries. Here we describe a hit discovery screening cascade designed to specifically identify hits that have the appropriate anti-parasitic properties to warrant further development. The cascade consists of a primary imaging-based assay followed by newly developed and appropriately scaled secondary assays to predict the cidality and rate-of-kill of the compounds. Finally, we incorporated a cytochrome P450 CYP51 biochemical assay to remove compounds that owe their phenotypic response to inhibition of this enzyme. We report the use of the cascade in profiling two small libraries containing clinically tested compounds and identify Clemastine, Azelastine, Ifenprodil, Ziprasidone and Clofibrate as molecules having appropriate profiles. Analysis of clinical derived pharmacokinetic and toxicity data indicates that none of these are appropriate for repurposing but they may represent suitable start points for further optimisation for the treatment of Chagas disease.

PMID: 27082760 [PubMed - indexed for MEDLINE]

Meeting report: 28th International Conference on Antiviral Research in Rome, Italy.

Antiviral Res. 2015 Nov;123:172-87

Authors: Vere Hodge RA

Abstract
The 28th International Conference on Antiviral Research (ICAR) was held in Rome, Italy from May 11 to 15, 2015. This article summarizes the principal invited lectures. Phillip Furman, the Elion award recipient, described the research leading to sofosbuvir. Dennis Liotta, who received the Holý award, described how an investigation into HIV entry inhibitors led to a new therapy for cancer patients. Erica Ollmann Saphire, winner of the Prusoff Young Investigator award, explored the world of viral proteins and how they remodel to perform different essential roles in viral replication. The keynote addresses, by Raffaele De Francesco and Michael Manns, reported on the remarkable progress made in the therapy of chronic HCV infections. A third keynote address, by Armand Sprecher, related the difficulties and successes of Médicins Sans Frontières in West Africa ravaged by the Ebola outbreak. There were three mini-symposia on RNA Viruses, Antiviral Chemistry and Emerging Viruses. There was a good collection of talks on RNA viruses (norovirus, rabies, dengue, HEV, HCV, and RSV). A highlight of the chemistry was the preparation of prodrugs for nucleotide triphosphates as this opens a door to new options. The third mini-symposium emphasized how research work in the antiviral area is continuing to expand and needs to do so with a sense of urgency. Although this meeting report covers only a few of the presentations, it aims to illustrate the great diversity of topics discussed at ICAR, bringing together knowledge and expertise from the whole spectrum of antiviral research.

PMID: 26431686 [PubMed - indexed for MEDLINE]

Repositioning organohalogen drugs: a case study for identification of potent B-Raf V600E inhibitors via docking and bioassay.

Sci Rep. 2016;6:31074

Authors: Li Y, Guo B, Xu Z, Li B, Cai T, Zhang X, Yu Y, Wang H, Shi J, Zhu W

Abstract
Drug repositioning has been attracting increasingly attention for its advantages of reducing costs and risks. Statistics showed that around one quarter of the marketed drugs are organohalogens. However, no study has been reported, to the best of our knowledge, to aim at efficiently repositioning organohalogen drugs, which may be attributed to the lack of accurate halogen bonding scoring function. Here, we present a study to show that two organohalogen drugs were successfully repositioned as potent B-Raf V600E inhibitors via molecular docking with halogen bonding scoring function, namely D(3)DOCKxb developed in our lab, and bioassay. After virtual screening by D(3)DOCKxb against the database CMC (Comprehensive Medicinal Chemistry), 3 organohalogen drugs that were predicted to form strong halogen bonding with B-Raf V600E were purchased and tested with ELISA-based assay. In the end, 2 of them, rafoxanide and closantel, were identified as potent inhibitors with IC50 values of 0.07 μM and 1.90 μM, respectively, which are comparable to that of vemurafenib (IC50: 0.17 μM), a marketed drug targeting B-Raf V600E. Single point mutagenesis experiments confirmed the conformations predicted by D(3)DOCKxb. And comparison experiment revealed that halogen bonding scoring function is essential for repositioning those drugs with heavy halogen atoms in their molecular structures.

PMID: 27501852 [PubMed - in process]