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1.
Nat Commun ; 13(1): 4976, 2022 08 25.
Article in English | MEDLINE | ID: mdl-36008486

ABSTRACT

The development of next-generation antimalarials that are efficacious against the human liver and asexual blood stages is recognized as one of the world's most pressing public health challenges. In recent years, aminoacyl-tRNA synthetases, including prolyl-tRNA synthetase, have emerged as attractive targets for malaria chemotherapy. We describe the development of a single-step biochemical assay for Plasmodium and human prolyl-tRNA synthetases that overcomes critical limitations of existing technologies and enables quantitative inhibitor profiling with high sensitivity and flexibility. Supported by this assay platform and co-crystal structures of representative inhibitor-target complexes, we develop a set of high-affinity prolyl-tRNA synthetase inhibitors, including previously elusive aminoacyl-tRNA synthetase triple-site ligands that simultaneously engage all three substrate-binding pockets. Several compounds exhibit potent dual-stage activity against Plasmodium parasites and display good cellular host selectivity. Our data inform the inhibitor requirements to overcome existing resistance mechanisms and establish a path for rational development of prolyl-tRNA synthetase-targeted anti-malarial therapies.


Subject(s)
Amino Acyl-tRNA Synthetases , Antimalarials , Plasmodium , Amino Acyl-tRNA Synthetases/chemistry , Antimalarials/chemistry , Antimalarials/pharmacology , Humans , Piperidines , Plasmodium falciparum , Quinazolinones , RNA, Transfer
2.
ACS Infect Dis ; 5(4): 515-520, 2019 04 12.
Article in English | MEDLINE | ID: mdl-30773881

ABSTRACT

We have previously identified the cytoplasmic prolyl tRNA synthetase in Plasmodium falciparum as the functional target of the natural product febrifugine and its synthetic analogue halofuginone (HFG), one of the most potent antimalarials discovered to date. However, our studies also discovered that short-term treatment of asexual blood stage P. falciparum with HFG analogues causes a 20-fold increase in intracellular proline, termed the adaptive proline response (APR), which renders parasites tolerant to HFG. This novel resistance phenotype lacks an apparent genetic basis but remains stable after drug withdrawal. On the basis of our findings that HFG treatment induces eIF2α phosphorylation, a sensitive marker and mediator of cellular stress, we here investigate if eIF2α-signaling is functionally linked to the APR. In our comparative studies using a parasite line lacking PfeIK1, the Plasmodium orthologue of the eIF2α-kinase GCN2 that mediates amino acid deprivation sensing, we show that HFG activity and the APR are independent from PfeIK1 and eIF2α signaling.


Subject(s)
Amino Acyl-tRNA Synthetases/metabolism , Eukaryotic Initiation Factor-2/metabolism , Plasmodium falciparum/metabolism , Proline/metabolism , Protozoan Proteins/metabolism , Amino Acyl-tRNA Synthetases/genetics , Antimalarials/pharmacology , Drug Resistance , Eukaryotic Initiation Factor-2/genetics , Humans , Malaria, Falciparum/parasitology , Phosphorylation , Piperidines/pharmacology , Plasmodium falciparum/drug effects , Plasmodium falciparum/enzymology , Plasmodium falciparum/genetics , Protozoan Proteins/genetics , Quinazolinones/pharmacology , Signal Transduction/drug effects
3.
Eur J Med Chem ; 102: 320-33, 2015 Sep 18.
Article in English | MEDLINE | ID: mdl-26295174

ABSTRACT

A series of 3-piperidin-4-yl-1H-indoles with building block diversity was synthesized based on a hit derived from an HTS whole-cell screen against Plasmodium falciparum. Thirty-eight compounds were obtained following a three-step synthetic approach and evaluated for anti-parasitic activity. The SAR shows that 3-piperidin-4-yl-1H-indole is intolerant to most N-piperidinyl modifications. Nevertheless, we were able to identify a new compound (10d) with lead-like properties (MW = 305; cLogP = 2.42), showing antimalarial activity against drug-resistant and sensitive strains (EC50 values ∼ 3 µM), selectivity for malaria parasite and no cross-resistance with chloroquine, thus representing a potential new chemotype for further optimization towards novel and affordable antimalarial drugs.


Subject(s)
Antimalarials/chemistry , Antimalarials/pharmacology , Indoles/pharmacology , Malaria/drug therapy , Niacinamide/analogs & derivatives , Plasmodium falciparum/drug effects , Antimalarials/chemical synthesis , Antimalarials/therapeutic use , Cell Survival/drug effects , Dose-Response Relationship, Drug , Hep G2 Cells , Humans , Indoles/chemical synthesis , Indoles/chemistry , Malaria/parasitology , Molecular Structure , Niacinamide/chemical synthesis , Niacinamide/chemistry , Niacinamide/pharmacology , Parasitic Sensitivity Tests , Plasmodium falciparum/growth & development , Structure-Activity Relationship
4.
PLoS One ; 10(5): e0126891, 2015.
Article in English | MEDLINE | ID: mdl-26024321

ABSTRACT

BACKGROUND: A guanine-rich strand within the promoter of the KRAS gene can fold into an intra-molecular G-quadruplex structure (G4), which has an important role in the regulation of KRAS transcription. We have previously identified indolo[3,2-b]quinolines with a 7-carboxylate group and three alkylamine side chains (IQ3A) as effective G4 stabilizers and promising selective anticancer leads. Herein we investigated the anticancer mechanism of action of these compounds, which we hypothesized due to stabilization of the G4 sequence in the KRAS promoter and subsequent down-regulation of gene expression. METHODOLOGY/PRINCIPAL FINDINGS: IQ3A compounds showed greater stabilization of G4 compared to duplex DNA structures and reduced KRAS promoter activity in a dual luciferase reporter assay. Moreover, IQ3A compounds showed high anti-proliferative activity in HCT116 and SW620 colon cancer cells (IC50 < 2.69 µM), without eliciting cell death in non-malignant HEK293T human embryonic kidney, and human colon fibroblasts CCD18co. IQ3A compounds significantly reduced KRAS mRNA and protein steady-state levels at IC50 concentrations, and increased p53 protein steady-state levels and cell death by apoptosis in HCT116 cells (mut KRAS, wt p53). Furthermore, KRAS silencing in HCT116 p53 wild-type (p53(+/+)) and null (p53(-/-)) isogenic cell lines induced a higher level of cell death, and a higher IQ3A-induced cell death in HCT116 p53(+/+) compared to HCT116 p53(-/-). CONCLUSIONS: Herein we provide evidence that G4 ligands such as IQ3A compounds can target G4 motifs present in KRAS promoter, down-regulate the expression of the mutant KRAS gene through inhibition of transcription and translation, and induce cell death by apoptosis in colon cancer cell lines. Thus, targeting KRAS at the genomic level with G4 ligands may be a new anticancer therapy strategy for colon cancer.


Subject(s)
Colonic Neoplasms/drug therapy , G-Quadruplexes/drug effects , Gene Expression Regulation, Neoplastic/drug effects , Quinolines/pharmacology , Apoptosis/drug effects , Cell Line, Tumor , Cell Proliferation/drug effects , Colonic Neoplasms/genetics , Genes, ras , HCT116 Cells , HEK293 Cells , Humans , Promoter Regions, Genetic , Quinolines/chemistry
5.
Sci Transl Med ; 7(288): 288ra77, 2015 May 20.
Article in English | MEDLINE | ID: mdl-25995223

ABSTRACT

The emergence of drug resistance is a major limitation of current antimalarials. The discovery of new druggable targets and pathways including those that are critical for multiple life cycle stages of the malaria parasite is a major goal for developing next-generation antimalarial drugs. Using an integrated chemogenomics approach that combined drug resistance selection, whole-genome sequencing, and an orthogonal yeast model, we demonstrate that the cytoplasmic prolyl-tRNA (transfer RNA) synthetase (PfcPRS) of the malaria parasite Plasmodium falciparum is a biochemical and functional target of febrifugine and its synthetic derivative halofuginone. Febrifugine is the active principle of a traditional Chinese herbal remedy for malaria. We show that treatment with febrifugine derivatives activated the amino acid starvation response in both P. falciparum and a transgenic yeast strain expressing PfcPRS. We further demonstrate in the Plasmodium berghei mouse model of malaria that halofuginol, a new halofuginone analog that we developed, is active against both liver and asexual blood stages of the malaria parasite. Halofuginol, unlike halofuginone and febrifugine, is well tolerated at efficacious doses and represents a promising lead for the development of dual-stage next-generation antimalarials.


Subject(s)
Amino Acyl-tRNA Synthetases/antagonists & inhibitors , Antimalarials/pharmacology , Enzyme Inhibitors/pharmacology , Malaria, Falciparum/drug therapy , Piperidines/pharmacology , Plasmodium falciparum/drug effects , Protozoan Proteins/antagonists & inhibitors , Quinazolines/pharmacology , Quinazolinones/pharmacology , Amino Acyl-tRNA Synthetases/metabolism , Animals , Antimalarials/chemistry , Antimalarials/toxicity , Computer-Aided Design , Disease Models, Animal , Dose-Response Relationship, Drug , Drug Design , Drug Resistance , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/toxicity , Erythrocytes/parasitology , Liver/parasitology , Malaria, Falciparum/blood , Malaria, Falciparum/parasitology , Mice , Models, Molecular , Molecular Structure , Molecular Targeted Therapy , Piperidines/chemistry , Piperidines/toxicity , Plasmodium falciparum/enzymology , Protozoan Proteins/metabolism , Quinazolines/chemistry , Quinazolines/toxicity , Quinazolinones/chemistry , Quinazolinones/toxicity , Structure-Activity Relationship , Time Factors
6.
Bioorg Med Chem ; 23(7): 1530-9, 2015 Apr 01.
Article in English | MEDLINE | ID: mdl-25725608

ABSTRACT

We recently reported that potent N10,O11-bis-alkylamine indolo[3,2-b]quinoline antimalarials act as hemozoin (Hz) growth inhibitors. To improve access and binding to the target we have now designed novel N10,N11-di-alkylamine bioisosteres. 3-Chloro derivatives (10a-f) showed selectivity for malaria parasite compared to human cells, high activity against Plasmodium falciparum chloroquine (CQ)-resistant strain W2 (IC50s between 20 and 158nM), good correlation with ß-hematin inhibition and improved vacuolar accumulation ratios, thus suggesting inhibition of Hz growth as one possible mechanism of action for these compounds. Moreover, our studies show that Hz is a valid target for the development of new antimalarials able to overcome CQ resistance.


Subject(s)
Antimalarials/chemical synthesis , Drug Design , Hemeproteins/antagonists & inhibitors , Plasmodium falciparum/drug effects , Quinolines/chemical synthesis , Antimalarials/pharmacology , Cryptolepis , Hemeproteins/metabolism , Humans , Quinolines/pharmacology
7.
PLoS One ; 9(8): e104015, 2014.
Article in English | MEDLINE | ID: mdl-25119572

ABSTRACT

Vascular endothelial growth factor-A (VEGF) is produced by most cancer cells as multiple isoforms, which display distinct biological activities. VEGF plays an undisputed role in tumour growth, vascularisation and metastasis; nevertheless the functions of individual isoforms in these processes remain poorly understood. We investigated the effects of three main murine isoforms (VEGF188, 164 and 120) on tumour cell behaviour, using a panel of fibrosarcoma cells we developed that express them individually under endogenous promoter control. Fibrosarcomas expressing only VEGF188 (fs188) or wild type controls (fswt) were typically mesenchymal, formed ruffles and displayed strong matrix-binding activity. VEGF164- and VEGF120-producing cells (fs164 and fs120 respectively) were less typically mesenchymal, lacked ruffles but formed abundant cell-cell contacts. On 3D collagen, fs188 cells remained mesenchymal while fs164 and fs120 cells adopted rounded/amoeboid and a mix of rounded and elongated morphologies respectively. Consistent with their mesenchymal characteristics, fs188 cells migrated significantly faster than fs164 or fs120 cells on 2D surfaces while contractility inhibitors accelerated fs164 and fs120 cell migration. VEGF164/VEGF120 expression correlated with faster proliferation rates and lower levels of spontaneous apoptosis than VEGF188 expression. Nevertheless, VEGF188 was associated with constitutively active/phosphorylated AKT, ERK1/2 and Stat3 proteins. Differences in proliferation rates and apoptosis could be explained by defective signalling downstream of pAKT to FOXO and GSK3 in fs188 and fswt cells, which also correlated with p27/p21 cyclin-dependent kinase inhibitor over-expression. All cells expressed tyrosine kinase VEGF receptors, but these were not active/activatable suggesting that inherent differences between the cell lines are governed by endogenous VEGF isoform expression through complex interactions that are independent of tyrosine kinase receptor activation. VEGF isoforms are emerging as potential biomarkers for anti-VEGF therapies. Our results reveal novel roles of individual isoforms associated with cancer growth and metastasis and highlight the importance of understanding their diverse actions.


Subject(s)
Cell Movement/genetics , Cell Proliferation/genetics , Fibrosarcoma/metabolism , Vascular Endothelial Growth Factor A/metabolism , Animals , Apoptosis , Carcinogenesis/genetics , Cell Adhesion , Cell Line, Tumor , Cell Survival/genetics , Fibrosarcoma/pathology , Gene Expression Regulation, Neoplastic , Mice , Neoplasm Metastasis/genetics , Protein Isoforms/chemistry , Protein Isoforms/metabolism , Receptors, Vascular Endothelial Growth Factor/metabolism , Vascular Endothelial Growth Factor A/chemistry
8.
Bioconjug Chem ; 25(6): 1043-51, 2014 Jun 18.
Article in English | MEDLINE | ID: mdl-24797834

ABSTRACT

Small molecule fluorophores are indispensable tools for modern biomedical imaging techniques. In this report, we present the development of a new class of BODIPY dyes based on an alkoxy-fluoro-boron-dipyrromethene core. These novel fluorescent dyes, which we term MayaFluors, are characterized by good aqueous solubility and favorable in vitro physicochemical properties. MayaFluors are readily accessible in good yields in a one-pot, two-step approach starting from well-established BODIPY dyes, and allow for facile modification with functional groups of relevance to bioconjugate chemistry and bioorthogonal labeling. Biological profiling in living cells demonstrates excellent membrane permeability, low nonspecific binding, and lack of cytotoxicity.


Subject(s)
Boron Compounds/analysis , Fluorescent Dyes/analysis , Molecular Imaging/methods , Boron Compounds/chemical synthesis , Boron Compounds/chemistry , Cell Membrane Permeability , Cell Survival , Female , Fluorescent Dyes/chemical synthesis , Fluorescent Dyes/chemistry , Humans , MCF-7 Cells , Molecular Structure , Solubility , Tumor Cells, Cultured
9.
J Med Chem ; 57(8): 3295-313, 2014 Apr 24.
Article in English | MEDLINE | ID: mdl-24673163

ABSTRACT

To get insight into the relevance of targeting hemozoin (Hz) crystals, two isomeric series, N5,N10-bis-alkylamine (2a-k) and N10,O11-bis-alkylamine (3a-k) indolo[3,2-b]quinolines, were evaluated for their in vitro activity against chloroquine (CQ)-resistant and sensitive strains of Plasmodium falciparum. In general, compounds of series 3 were more active than isomers 2, with IC50/LD50 ranging from 25/233 nM (3i) to 1.3 (3a)/10.7 (3b) µM. SAR analyses showed that lipophilicity and chlorine substitution at C3 increased both cytostatic and cytocidal activities. Both series bound to hematin monomer, inhibited ß-hematin formation in vitro, delayed intraerythrocytic parasite development with apparent inhibition of Hz biocrystallization, and showed higher cytocidal activity against schizonts. In addition, cytostatic and cytocidal activities of series 3, but not those of isomers 2, correlated with calculated vacuole accumulation ratios, suggesting different capacities of 2 and 3 to bind to the Hz crystal face {001} exposed on the vacuole aqueous medium and different mechanisms of cytocidal potency.


Subject(s)
Antimalarials/chemical synthesis , Antineoplastic Agents/chemical synthesis , Hemeproteins/metabolism , Quinolines/chemical synthesis , Antimalarials/pharmacology , Antineoplastic Agents/pharmacology , Chloroquine/pharmacology , Hemin/metabolism , Hep G2 Cells , Humans , Ligands , Plasmodium falciparum/drug effects , Quinolines/pharmacology , Structure-Activity Relationship
10.
Curr Cancer Drug Targets ; 13(8): 814-28, 2013 Oct.
Article in English | MEDLINE | ID: mdl-23876050

ABSTRACT

The resistance of tumors to a number of structurally and functionally unrelated chemotherapeutic drugs has been a major obstacle for successful cancer chemotherapy. An important mechanism leading to multidrug resistance (MDR) is the overexpression of the 170 kDa P-glycoprotein (P-gp), which is a member of the ATP-binding cassette (ABC) superfamily of membrane transporters, encoded by the MDR1 gene. Aiming to overcome MDR and due to the clinical failure of P-gp inhibitors, downregulation of MDR1 expression by small molecules has been studied as a possible cancer adjuvant chemotherapy. Here we review the current knowledge on MDR1 gene expression downregulation by small molecules and the mechanisms underlying those effects observed in cancer cell lines, in an attempt to identify targets for future therapeutic interventions.


Subject(s)
Antineoplastic Agents/therapeutic use , Drug Evaluation, Preclinical , Drug Resistance, Multiple , Drug Resistance, Neoplasm/genetics , Genes, MDR/drug effects , Neoplasms/drug therapy , Neoplasms/metabolism , Animals , Genes, MDR/physiology , Humans , Small Molecule Libraries
11.
Bioorg Med Chem Lett ; 20(19): 5634-7, 2010 Oct 01.
Article in English | MEDLINE | ID: mdl-20801652

ABSTRACT

Quindolone derivatives, designed to target the malaria parasite digestive vacuole and heme detoxification pathway, have been synthesized by reaction with 2-chloro-N,N-diethylethanamine. This reaction gave N,O-, N,N- and O-alkylated products containing one or two basic side-chains. The compounds were evaluated for antiplasmodial activity against the chloroquine-resistant Plasmodium falciparum W2 strain and for cytotoxicity in HepG2 A16 hepatic cells. By incorporating alkylamine side chains and chlorine atoms in the quindolone nucleus we transformed the inactive tetracyclic parent quindolones into moderate or highly active and selective antimalarial compounds. The most active and selective compound, 5c, showed an IC(50)=51 nM for P. falciparum and a selectivity ratio of 98.


Subject(s)
Antimalarials/chemistry , Carbolines/chemistry , Indolequinones/chemistry , Quinolones/chemistry , Alkylation , Antimalarials/chemical synthesis , Antimalarials/toxicity , Carbolines/chemical synthesis , Carbolines/toxicity , Drug Resistance , Hemeproteins/chemistry , Hemeproteins/metabolism , Hep G2 Cells , Humans , Indolequinones/chemical synthesis , Indolequinones/toxicity , Plasmodium falciparum/drug effects , Quinolones/chemical synthesis , Quinolones/toxicity
12.
World J Gastroenterol ; 13(9): 1466-70, 2007 Mar 07.
Article in English | MEDLINE | ID: mdl-17457985

ABSTRACT

Hepatic abscess due to perforation of the gastrointestinal tract caused by ingested foreign bodies is uncommon. Pre-operative diagnosis is difficult as patients are often unaware of the foreign body ingestion and symptoms and imagiology are usually non-specific. The authors report a case of 62-year-old woman who was admitted with fever and abdominal pain. Further investigation revealed hepatic abscess, without resolution despite antibiotic therapy. A liver abscess resulting from perforation and intra-hepatic migration of a bone coming from the pilorum was diagnosed by surgery. The literature concerning foreign body-induced perforation of the gastrointestinal tract complicated by liver abscess is reviewed.


Subject(s)
Foreign-Body Migration/complications , Liver Abscess/diagnosis , Liver Abscess/etiology , Bone and Bones , Female , Foreign-Body Migration/diagnosis , Humans , Intestinal Perforation/complications , Intestinal Perforation/diagnosis , Intestinal Perforation/etiology , Laparotomy , Liver Abscess/diagnostic imaging , Middle Aged , Tomography, X-Ray Computed
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