RESUMO
CoaBC, part of the vital coenzyme A biosynthetic pathway in bacteria, has recently been validated as a promising antimicrobial target. In this work, we employed native ion mobility-mass spectrometry to gain structural insights into the phosphopantothenoylcysteine synthetase domain of E. coli CoaBC. Moreover, native mass spectrometry was validated as a screening tool to identify novel inhibitors of this enzyme, highlighting the utility and versatility of this technique both for structural biology and for drug discovery.
Assuntos
Carboxiliases/química , Avaliação Pré-Clínica de Medicamentos/métodos , Proteínas de Escherichia coli/química , Escherichia coli/enzimologia , Espectrometria de Massas/métodos , Complexos Multienzimáticos/química , Peptídeo Sintases/química , Carboxiliases/antagonistas & inibidores , Carboxiliases/metabolismo , Dimerização , Inibidores Enzimáticos/química , Escherichia coli/química , Escherichia coli/efeitos dos fármacos , Escherichia coli/genética , Proteínas de Escherichia coli/antagonistas & inibidores , Proteínas de Escherichia coli/metabolismo , Cinética , Complexos Multienzimáticos/antagonistas & inibidores , Complexos Multienzimáticos/metabolismo , Peptídeo Sintases/antagonistas & inibidores , Peptídeo Sintases/metabolismo , Domínios ProteicosRESUMO
Aurora A kinase, a cell division regulator, is frequently overexpressed in various cancers, provoking genome instability and resistance to antimitotic chemotherapy. Localization and enzymatic activity of Aurora A are regulated by its interaction with the spindle assembly factor TPX2. We have used fragment-based, structure-guided lead discovery to develop small molecule inhibitors of the Aurora A-TPX2 protein-protein interaction (PPI). Our lead compound, CAM2602, inhibits Aurora A:TPX2 interaction, binding Aurora A with 19 nM affinity. CAM2602 exhibits oral bioavailability, causes pharmacodynamic biomarker modulation, and arrests the growth of tumor xenografts. CAM2602 acts by a novel mechanism compared to ATP-competitive inhibitors and is highly specific to Aurora A over Aurora B. Consistent with our finding that Aurora A overexpression drives taxane resistance, these inhibitors synergize with paclitaxel to suppress the outgrowth of pancreatic cancer cells. Our results provide a blueprint for targeting the Aurora A-TPX2 PPI for cancer therapy and suggest a promising clinical utility for this mode of action.
RESUMO
BRCA2 controls RAD51 recombinase during homologous DNA recombination (HDR) through eight evolutionarily conserved BRC repeats, which individually engage RAD51 via the motif Phe-x-x-Ala. Using structure-guided molecular design, templated on a monomeric thermostable chimera between human RAD51 and archaeal RadA, we identify CAM833, a 529 Da orthosteric inhibitor of RAD51:BRC with a Kd of 366 nM. The quinoline of CAM833 occupies a hotspot, the Phe-binding pocket on RAD51 and the methyl of the substituted α-methylbenzyl group occupies the Ala-binding pocket. In cells, CAM833 diminishes formation of damage-induced RAD51 nuclear foci; inhibits RAD51 molecular clustering, suppressing extended RAD51 filament assembly; potentiates cytotoxicity by ionizing radiation, augmenting 4N cell-cycle arrest and apoptotic cell death and works with poly-ADP ribose polymerase (PARP)1 inhibitors to suppress growth in BRCA2-wildtype cells. Thus, chemical inhibition of the protein-protein interaction between BRCA2 and RAD51 disrupts HDR and potentiates DNA damage-induced cell death, with implications for cancer therapy.
Assuntos
Proteína BRCA2/antagonistas & inibidores , Rad51 Recombinase/antagonistas & inibidores , Bibliotecas de Moléculas Pequenas/farmacologia , Proteína BRCA2/química , Proteína BRCA2/metabolismo , Morte Celular/efeitos dos fármacos , Cristalografia por Raios X , Dano ao DNA , Humanos , Modelos Moleculares , Conformação Molecular , Ligação Proteica/efeitos dos fármacos , Rad51 Recombinase/química , Rad51 Recombinase/metabolismo , Bibliotecas de Moléculas Pequenas/síntese química , Bibliotecas de Moléculas Pequenas/química , Células Tumorais CultivadasRESUMO
A new and extensive set of 4-(6-iodo-H-imidazo[1,2-a]pyridin-2-yl)-N-dimethylbenzeneamine (IMPY) derivatives was synthesized and assayed for affinity toward human Abeta plaques. 6-Ethylthio- (12h), 6-cyano- (12e), 6-nitro- (12f), and 6-p-methoxybenzylthio- (15d) analogues were discovered to have high affinity (KI < 10 nM). However, introduction of a hydrophilic thioether group in the 6-position (15a-c, 15e-g) reduced or abolished affinity. In secondary N-methyl analogues, a bromo substituent in the adjacent ring position (14a) imparted high affinity (KI = 7.4 nM) whereas a methyl substituent did not (14c). The tolerance for nonhydrophilic thioether substituents in the 6-position opens up the possibility of developing new sensitive positron emission tomography radioligands for imaging human Abeta plaques in Alzheimer's disease, especially in view of the amenability of thioethers to be labeled with carbon-11 or fluorine-18 through S-alkylation reactions. The structure-activity relationships revealed in this study extends insight into the topography of the binding site for IMPY-like ligands in human Abeta plaques.
Assuntos
Peptídeos beta-Amiloides/metabolismo , Compostos de Anilina/síntese química , Imidazóis/síntese química , Iodo , Piridinas/síntese química , Idoso de 80 Anos ou mais , Doença de Alzheimer/metabolismo , Peptídeos beta-Amiloides/química , Compostos de Anilina/química , Compostos de Anilina/farmacologia , Encéfalo/metabolismo , Feminino , Humanos , Imidazóis/química , Imidazóis/farmacologia , Ligantes , Fragmentos de Peptídeos/química , Ligação Proteica , Piridinas/química , Piridinas/farmacologia , Ensaio Radioligante , Relação Estrutura-AtividadeRESUMO
This study evaluated (18)F-labeled IMPY [6-iodo-2-(4'-N,N-dimethylamino)phenylimidazo[1,2-a]pyridine] derivatives as agents for imaging beta-amyloid plaque with positron emission tomography (PET). The precursor for radiolabeling and reference compounds was synthesized in up to five steps from commercially accessible starting materials. One of the two N-methyl groups of IMPY was substituted with either a 3-fluoropropyl (FPM-IMPY) or a 2-fluoroethyl (FEM-IMPY) group. FPM-IMPY and FEM-IMPY were found to have moderate affinity for Abeta-aggregates with K(i) = 27 +/- 8 and 40 +/- 5 nM, respectively. A "one-pot" method for (18)F-2-fluoroethylation and (18)F-3-fluoropropylation of the precursor was developed. The overall decay-corrected radiochemical yields were 26-51%. In PET experiments with normal mouse, high uptake of activity was obtained in the brain after iv injection of each probe: 6.4% ID/g for [(18)F]FEM-IMPY at 1.2 min, and 5.7% ID/g for [(18)F]FPM-IMPY at 0.8 min. These values were similar to those of [(123)I/(125)I]IMPY (7.2% ID/g at 2 min). Polar and nonpolar radioactive metabolites were observed in both plasma and brain homogenates after injection of [(18)F]FEM or [(18)F]FPM-IMPY. In contrast to the single-exponential washout of [(123)I/(125)I]IMPY, the washouts of brain activity for the two fluorinated analogues were biphasic, with an initial rapid phase over 20 min and a subsequent much slower phase. Residual brain activity at 2 h, which may represent polar metabolites trapped in the brain, was 4.5% ID/g for [(18)F]FEM-IMPY and 2.1% ID/g for [(18)F]FPM-IMPY. Substantial skull uptake of [(18)F]fluoride was also clearly observed. With a view to slow the metabolism of [(18)F]FEM-IMPY, an analogue was prepared with deuteriums substituted for the four ethyl hydrogens. However, D(4)-[(18)F]FEM-IMPY showed the same brain uptake and clearance as the protio analogue. Metabolism of the [(18)F]FEM-IMPY was appreciably slower in rhesus monkey than in mouse. Autoradiography of postmortem brain sections of human Alzheimer's disease patients with [(18)F]FEM-IMPY showed high displaceable uptake in gray matter and low nonspecific binding in the white matter. This study demonstrates that the IMPY derivatives have favorable in vivo brain pharmacokinetics and a moderate affinity for imaging beta-amyloid plaques; however, further improvements are needed to reduce radioactive metabolites, increase binding affinity, and reduce lipophilicity.
Assuntos
Doença de Alzheimer/diagnóstico por imagem , Peptídeos beta-Amiloides/metabolismo , Imidazóis/síntese química , Piridinas/síntese química , Doença de Alzheimer/metabolismo , Peptídeos beta-Amiloides/química , Animais , Autorradiografia , Encéfalo/diagnóstico por imagem , Encéfalo/metabolismo , Cromatografia Líquida , Feminino , Radioisótopos de Flúor , Humanos , Imidazóis/metabolismo , Técnicas In Vitro , Marcação por Isótopo , Ligantes , Macaca mulatta , Masculino , Camundongos , Pessoa de Meia-Idade , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/metabolismo , Piridinas/metabolismo , Espectrometria de Massas por Ionização por Electrospray , Distribuição Tecidual , Tomografia Computadorizada de EmissãoRESUMO
Herein, we describe the discovery of potent and highly selective inhibitors of both CDK4 and CDK6 via structure-guided optimization of a fragment-based screening hit. CDK6 X-ray crystallography and pharmacokinetic data steered efforts in identifying compound 6, which showed >1000-fold selectivity for CDK4 over CDKs 1 and 2 in an enzymatic assay. Furthermore, 6 demonstrated in vivo inhibition of pRb-phosphorylation and oral efficacy in a Jeko-1 mouse xenograft model.
RESUMO
On the basis of our understanding on the binding interactions of the benzothiophene template within the FIXa active site by X-ray crystallography and molecular modeling studies, we developed our SAR strategy by targeting the 4-position of the template to access the S1 beta and S2-S4 sites. A number of highly selective and potent factor Xa (FXa) and FIXa inhibitors were identified by simple switch of functional groups with conformational changes toward the S2-S4 sites.