RESUMO
Studies have shown that disrupting the formation of the ligand-RET-GFRα complex could be an effective way of treating pain and itch. Compared to traditional high-throughput screens, DNA encoded libraries (DELs) have distinguished themselves as a powerful technology for hit identification in recent years. The present work demonstrates the use of DEL technology identifying compound 16 as the first GFRa2/GFRa3 small molecule inhibitor (0.1/0.2 µM respectively) selective over RET. This molecule represents an opportunity to advance the development of small-molecule inhibitors targeting the GFRα-RET interface for the treatment of pain and itch.
Assuntos
DNA , Receptores de Fator Neurotrófico Derivado de Linhagem de Célula Glial , Bibliotecas de Moléculas Pequenas , Bibliotecas de Moléculas Pequenas/química , Bibliotecas de Moléculas Pequenas/farmacologia , Bibliotecas de Moléculas Pequenas/síntese química , Humanos , DNA/química , DNA/metabolismo , Receptores de Fator Neurotrófico Derivado de Linhagem de Célula Glial/metabolismo , Receptores de Fator Neurotrófico Derivado de Linhagem de Célula Glial/antagonistas & inibidores , Descoberta de Drogas , Relação Estrutura-Atividade , Estrutura Molecular , Relação Dose-Resposta a DrogaRESUMO
N-substituted azaindoles were discovered as potent pan-PIM inhibitors. Lead optimization, guided by structure and focused on physico-chemical properties allowed us to solve inherent hERG and permeability liabilities, and provided compound 27, which subsequently impacted KG-1 tumor growth in a mouse model.
Assuntos
Antineoplásicos/farmacologia , Compostos Aza/farmacologia , Indóis/farmacologia , Inibidores de Proteínas Quinases/farmacologia , Animais , Antineoplásicos/síntese química , Antineoplásicos/metabolismo , Compostos Aza/síntese química , Compostos Aza/metabolismo , Linhagem Celular Tumoral , Cristalografia por Raios X , Humanos , Indóis/síntese química , Indóis/metabolismo , Camundongos , Piperidinas/síntese química , Piperidinas/metabolismo , Piperidinas/farmacologia , Ligação Proteica , Inibidores de Proteínas Quinases/síntese química , Inibidores de Proteínas Quinases/metabolismo , Proteínas Proto-Oncogênicas c-pim-1/antagonistas & inibidores , Proteínas Proto-Oncogênicas c-pim-1/metabolismo , Pirrolidinas/síntese química , Pirrolidinas/metabolismo , Pirrolidinas/farmacologia , Ratos , Estereoisomerismo , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
N-substituted azaindoles were discovered as promising pan-PIM inhibitors. Lead optimization is described en route toward the identification of a clinical candidate. Modulation of physico-chemical properties allowed to solve inherent hERG and permeability liabilities. Compound 17 showed tumor growth inhibition in a KG1 tumor-bearing mouse model.
Assuntos
Antineoplásicos/farmacologia , Descoberta de Drogas , Indóis/farmacologia , Inibidores de Proteínas Quinases/farmacologia , Proteínas Proto-Oncogênicas c-pim-1/antagonistas & inibidores , Animais , Antineoplásicos/administração & dosagem , Antineoplásicos/química , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Indóis/administração & dosagem , Indóis/química , Camundongos , Estrutura Molecular , Neoplasias Experimentais/tratamento farmacológico , Neoplasias Experimentais/metabolismo , Neoplasias Experimentais/patologia , Inibidores de Proteínas Quinases/administração & dosagem , Inibidores de Proteínas Quinases/química , Proteínas Proto-Oncogênicas c-pim-1/metabolismo , Ratos , Relação Estrutura-AtividadeRESUMO
Novel N-substituted azaindoles have been discovered as PIM1 inhibitors. X-ray structures have played a significant role in orienting the chemistry effort in the initial phase of hit confirmation. Disclosure of an unconventional binding mode for 1 and 2, as demonstrated by X-ray crystallography, is presented and was an important factor in selecting and advancing a lead series.
Assuntos
Indóis/química , Indóis/farmacologia , Inibidores de Proteínas Quinases/metabolismo , Inibidores de Proteínas Quinases/farmacologia , Proteínas Proto-Oncogênicas c-pim-1/antagonistas & inibidores , Sítios de Ligação , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Cristalografia por Raios X , Avaliação Pré-Clínica de Medicamentos , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Indóis/metabolismo , Concentração Inibidora 50 , Simulação de Dinâmica Molecular , Inibidores de Proteínas Quinases/química , Proteínas Serina-Treonina Quinases/antagonistas & inibidores , Proteínas Serina-Treonina Quinases/metabolismo , Estrutura Terciária de Proteína , Proteínas Proto-Oncogênicas/antagonistas & inibidores , Proteínas Proto-Oncogênicas/metabolismo , Proteínas Proto-Oncogênicas c-pim-1/metabolismo , Relação Estrutura-AtividadeRESUMO
N-Substituted azaindoles have been discovered as pan-PIM kinase inhibitors. Initial SAR, early ADME and PK/PD data of a series of compounds is described and led to the identification of promising pan-PIM inhibitors which validated our interest in the 7-azaindole scaffold and led us to pursue the identification of a clinical candidate.
Assuntos
Indóis/química , Indóis/farmacologia , Inibidores de Proteínas Quinases/química , Inibidores de Proteínas Quinases/farmacologia , Proteínas Proto-Oncogênicas c-pim-1/metabolismo , Animais , Cristalografia por Raios X , Avaliação Pré-Clínica de Medicamentos , Ativação Enzimática/efeitos dos fármacos , Meia-Vida , Humanos , Indóis/metabolismo , Concentração Inibidora 50 , Camundongos , Microssomos Hepáticos/efeitos dos fármacos , Microssomos Hepáticos/metabolismo , Inibidores de Proteínas Quinases/metabolismo , Inibidores de Proteínas Quinases/farmacocinética , Proteínas Proto-Oncogênicas c-pim-1/química , Ratos , Relação Estrutura-AtividadeRESUMO
Postchemotherapy relapse presents a major unmet medical need in acute myeloid leukemia (AML), where treatment options are limited. CD25 is a leukemic stem cell marker and a conspicuous prognostic marker for overall/relapse-free survival in AML. Rare occurrence of genetic alterations among PIM family members imposes a substantial hurdle in formulating a compelling patient stratification strategy for the clinical development of selective PIM inhibitors in cancer. Here we show that CD25, a bona fide STAT5 regulated gene, is a mechanistically relevant predictive biomarker for sensitivity to PIM kinase inhibitors. Alone or in combination with tyrosine kinase inhibitors, PIM inhibitors can suppress STAT5 activation and significantly shorten the half-life of MYC to achieve substantial growth inhibition of high CD25-expressing AML cells. Our results highlight the importance of STAT5 and MYC in rendering cancer cells sensitive to PIM inhibitors. Because the presence of a CD25-positive subpopulation in leukemic blasts correlates with poor overall or relapse-free survival, our data suggest that a combination of PIM inhibitors with chemotherapy and tyrosine kinase inhibitors could improve long-term therapeutic outcomes in CD25-positive AML.
Assuntos
Antineoplásicos/farmacologia , Crise Blástica , Regulação Leucêmica da Expressão Gênica/efeitos dos fármacos , Subunidade alfa de Receptor de Interleucina-2/metabolismo , Proteólise/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-myc/metabolismo , Proteínas Proto-Oncogênicas c-pim-1/antagonistas & inibidores , Fator de Transcrição STAT5/metabolismo , Antineoplásicos/química , Crise Blástica/tratamento farmacológico , Crise Blástica/genética , Crise Blástica/metabolismo , Crise Blástica/patologia , Feminino , Células HL-60 , Humanos , Subunidade alfa de Receptor de Interleucina-2/genética , Leucemia Mieloide Aguda/tratamento farmacológico , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/metabolismo , Leucemia Mieloide Aguda/patologia , Masculino , Proteínas Proto-Oncogênicas c-myc/genética , Proteínas Proto-Oncogênicas c-pim-1/genética , Proteínas Proto-Oncogênicas c-pim-1/metabolismo , Fator de Transcrição STAT5/genéticaRESUMO
We describe structure-based optimization of a series of novel 2,4-diaminopyrimidine MK2 inhibitors. Co-crystal structures (see accompanying Letter) demonstrated a unique inhibitor binding mode. Resulting inhibitors had IC(50) values as low as 19nM and moderate selectivity against a kinase panel. Compounds 15, 31a, and 31b inhibit TNFalpha production in peripheral human monocytes.
Assuntos
Anti-Inflamatórios/química , Peptídeos e Proteínas de Sinalização Intracelular/antagonistas & inibidores , Inibidores de Proteínas Quinases/química , Proteínas Serina-Treonina Quinases/antagonistas & inibidores , Pirimidinas/química , Administração Oral , Animais , Anti-Inflamatórios/síntese química , Anti-Inflamatórios/farmacocinética , Sítios de Ligação , Simulação por Computador , Cristalografia por Raios X , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Inibidores de Proteínas Quinases/síntese química , Inibidores de Proteínas Quinases/farmacocinética , Proteínas Serina-Treonina Quinases/metabolismo , Pirimidinas/síntese química , Pirimidinas/farmacocinética , Ratos , Ratos Sprague-Dawley , Relação Estrutura-Atividade , Fator de Necrose Tumoral alfa/metabolismoRESUMO
Evaluation of hit chemotypes from high throughput screening identified a novel series of 2,4-disubstituted thieno[2,3-c]pyridines as COT kinase inhibitors. Structural modifications exploring SAR at the 2- and 4-positions resulting in inhibitors with improved enzyme potency and cellular activity are disclosed.
Assuntos
MAP Quinase Quinase Quinases/antagonistas & inibidores , Modelos Moleculares , Proteínas Proto-Oncogênicas/antagonistas & inibidores , Piridinas/síntese química , Piridinas/farmacologia , Tiofenos/síntese química , Tiofenos/farmacologia , Técnicas de Química Combinatória , Cristalografia por Raios X , Humanos , Conformação Molecular , Estrutura Molecular , Piridinas/química , Relação Estrutura-Atividade , Tiofenos/químicaRESUMO
Tumor cells display fundamental changes in metabolism and nutrient uptake in order to utilize additional nutrient sources to meet their enhanced bioenergetic requirements. Glutamine (Gln) is one such nutrient that is rapidly taken up by tumor cells to fulfill this increased metabolic demand. A vital step in the catabolism of glutamine is its conversion to glutamate by the mitochondrial enzyme glutaminase (GLS). This study has identified GLS a potential therapeutic target in breast cancer, specifically in the basal subtype that exhibits a deregulated glutaminolysis pathway. Using inducible shRNA mediated gene knockdown, we discovered that loss of GLS function in triple-negative breast cancer (TNBC) cell lines with a deregulated glutaminolysis pathway led to profound tumor growth inhibition in vitro and in vivo. GLS knockdown had no effect on growth and metabolite levels in non-TNBC cell lines. We rescued the anti-tumor effect of GLS knockdown using shRNA resistant cDNAs encoding both GLS isoforms and by addition of an α-ketoglutarate (αKG) analog thus confirming the critical role of GLS in TNBC. Pharmacological inhibition of GLS with the small molecule inhibitor CB-839 reduced cell growth and led to a decrease in mammalian target of rapamycin (mTOR) activity and an increase in the stress response pathway driven by activating transcription factor 4 (ATF4). Finally, we found that GLS inhibition synergizes with mTOR inhibition, which introduces the possibility of a novel therapeutic strategy for TNBC. Our study revealed that GLS is essential for the survival of TNBC with a deregulated glutaminolysis pathway. The synergistic activity of GLS and mTOR inhibitors in TNBC cell lines suggests therapeutic potential of this combination for the treatment of vulnerable subpopulations of TNBC.
Assuntos
Glutaminase/metabolismo , Glutamina/metabolismo , Serina-Treonina Quinases TOR/antagonistas & inibidores , Neoplasias de Mama Triplo Negativas/enzimologia , Linhagem Celular Tumoral , Feminino , Humanos , Neoplasias de Mama Triplo Negativas/metabolismo , Neoplasias de Mama Triplo Negativas/patologiaRESUMO
The purpose was to apply oxidative crosslinking reactions to the study of recognition and signaling mechanisms associated to G-protein-coupled receptors. Using a ruthenium chelate, Ru(bipy)(3)(2+), as photosensitizer and visible light irradiation, in the presence of ammonium persulfate, we performed fast and efficient covalent labeling of the B(2) bradykinin receptor by agonist or antagonist ligands possessing a radio-iodinated phenol moiety. The chemical and topographical specificities of these crosslinking experiments were investigated. The strategy could also be applied to the covalent labeling of the B(1) bradykinin receptor, the AT(1) angiotensin II receptor, the V(1a) vasopressin receptor and the oxytocin receptor. Interestingly, we demonstrated the possibility to covalently label the AT(1) and B(2) receptors with functionalized ligands. The potential applications of metal-chelate chemistry to receptor structural and signaling studies through intramolecular or intermolecular crosslinking are presented.
Assuntos
Quelantes/química , Compostos Organometálicos/química , Marcadores de Fotoafinidade , Fármacos Fotossensibilizantes/farmacologia , Receptores Acoplados a Proteínas G/química , Rutênio/química , Sequência de Aminoácidos , Quelantes/síntese química , Ligantes , Luz , Dados de Sequência Molecular , Compostos Organometálicos/síntese química , Oxirredução , Peptídeos/química , Fotoquímica , Ligação Proteica/fisiologia , Receptores Acoplados a Proteínas G/fisiologia , Sensibilidade e Especificidade , Transdução de Sinais/fisiologia , Relação Estrutura-AtividadeRESUMO
New insights into the structure-activity relationship of the peptide hormone oxytocin are presented. Incorporation of the novel cis-prolyl mimic 2,2-dimethyl-1,3-thiazolidine-4-carboxylic acid (pseudoproline, PsiPro) at position 7 of the hormone yielded the analogue [Cys(Psi(Me,Me)pro)]7oxytocin (1) that showed a 92-95% induction of the cis peptide bond conformation between Cys6 and PsiPro7, as determined by one- and two-dimensional NMR spectra in water and in DMSO-d6. The impact of the dimethyl moiety regarding conformation and bioactivity was investigated by the synthesis of the corresponding dihydro compound, [Cys(Psi(H,H)pro)]7oxytocin (2). Biological tests of the uterotonic activity, the pressor activity, and the binding affinity to the rat and human oxytocin receptors were carried out. As a most significant result, no antagonistic activities were found for both the cis-constrained analogue 1 and analogue 2, suggesting that a cis conformation between residues 6 and 7 of the molecule does not result in antagonistic activity. However, the about 10-fold reduction in agonistic activity of 1 as compared to oxytocin is consistent with the reduction of the trans conformation from 90% for oxytocin to 5-8% for compound 1. Compound 1 retained a high binding affinity for the oxytocin receptor, with K(i) values of 8.0 and 1.9 nM for the rat and the human receptor, respectively. The correlation between the biological activities and the cis contents obtained from NMR analysis for compounds 1, 2, and oxytocin leads to the hypothesis that a cis/trans conformational change plays an important role in oxytocin receptor binding and activation.
Assuntos
Ocitocina/análogos & derivados , Ocitocina/síntese química , Prolina/análogos & derivados , Receptores de Ocitocina/agonistas , Receptores de Ocitocina/antagonistas & inibidores , Tiazóis/química , Animais , Ligação Competitiva , Pressão Sanguínea/efeitos dos fármacos , Células CHO , Cricetinae , Cricetulus , Feminino , Humanos , Técnicas In Vitro , Espectroscopia de Ressonância Magnética , Masculino , Conformação Molecular , Mimetismo Molecular , Ocitocina/farmacologia , Prolina/química , Ensaio Radioligante , Ratos , Estereoisomerismo , Relação Estrutura-Atividade , Contração Uterina/efeitos dos fármacos , Útero/efeitos dos fármacos , Útero/metabolismo , Útero/fisiologiaRESUMO
We designed and synthesized new photoactivatable linear vasopressin analogues containing benzophenone photophores. All compounds were monitored and purified using RP-HPLC and characterized by mass spectrometry. Affinity and selectivity were determined in CHO cells expressing either human V(1a), V(1b) or V(2) receptor subtypes. Within the series, compounds 6 (PhCH(2)CO-lBpa-Phe-Gln-Asn-Arg-Pro-Arg-Tyr(3I)-NH(2)) and 9 (PhCH(2)CO-dBpa-Phe-Gln-Asn-Arg-Pro-Arg-Tyr(3I)-NH(2)), containing a benzoylphenylalanine residue (Bpa), were selected and their antagonistic properties determined (K(inact) = 1.87 and 0.35 nM, respectively). The dissociation constant of the most potent candidate (compound 9) was further calculated from saturation experiments using the (125)I derivative (K(d) = 0.07 +/- 0.01 nM). Photolabeling experiments using radioactive compound 9 as a probe were specific and UV-dependent and allowed the identification of two bands at molecular masses around 85-90 kDa and 46 kDa, respectively, as previously described by Phalipou et al., using two photoreactive linear azidopeptide antagonists. The results suggest therefore that compound 9 is a potent new tool for the accurate mapping of the human V(1a) receptor antagonist binding site.
Assuntos
Antagonistas dos Receptores de Hormônios Antidiuréticos , Benzofenonas/síntese química , Oligopeptídeos/síntese química , Marcadores de Fotoafinidade/síntese química , Animais , Benzofenonas/química , Benzofenonas/farmacologia , Sítios de Ligação , Células CHO , Cricetinae , Cricetulus , Humanos , Radioisótopos do Iodo , Cinética , Luz , Oligopeptídeos/química , Oligopeptídeos/farmacologia , Marcadores de Fotoafinidade/química , Marcadores de Fotoafinidade/farmacologia , Ensaio Radioligante , Receptores de Vasopressinas/metabolismo , Relação Estrutura-AtividadeRESUMO
We report a novel chemical class of potent oxytocin receptor antagonists showing a high degree of selectivity against the closely related vasopressin receptors (V1a, V1b, V2). An initial compound, 7, was shown to be active in an animal model of preterm labor when administered by the intravenous but not by the oral route. Stepwise SAR investigations around the different structural elements revealed one position, the arenesulfonyl moiety, to be amenable to structural changes. Consequently, this position was used to introduce a variety of substituents to improve the physicochemical properties. Some of the resulting analogues were found to be superior to 7 both in terms of potency in vitro and aqueous solubility, which translated into significantly improved efficacy in the animal model after intravenous and oral administration. The best compound, 73, potently inhibited oxytocin-induced uterine contractions in nonpregnant rats and reduced spontaneous uterine contractions in late-term pregnant rats.
Assuntos
Hidrazinas/síntese química , Receptores de Ocitocina/antagonistas & inibidores , Sulfonamidas/síntese química , Administração Oral , Animais , Antagonistas dos Receptores de Hormônios Antidiuréticos , Ligação Competitiva , Linhagem Celular , Cricetinae , Cricetulus , Feminino , Humanos , Hidrazinas/química , Hidrazinas/farmacologia , Técnicas In Vitro , Trabalho de Parto Prematuro/fisiopatologia , Trabalho de Parto Prematuro/prevenção & controle , Gravidez , Ensaio Radioligante , Ratos , Ratos Sprague-Dawley , Relação Estrutura-Atividade , Sulfonamidas/química , Sulfonamidas/farmacologia , Contração Uterina/efeitos dos fármacosRESUMO
G protein-coupled receptor (GPCR) oligomerization is a growing concept that has emerged from several studies suggesting that GPCRs can form both homo- and heterodimers. Using both coimmunoprecipitation and bioluminescence resonance energy transfer (BRET) approaches, we established that the vasopressin V1a, V2, and the oxytocin receptors exist as homo- and hetero-dimers in transfected human embryonic kidney 293T cells. Each receptor protomer had a similar propensity to form homo- and heterodimers, indicating that their relative expression levels may determine the homo-/heterodimer ratio. The finding that immature forms of the receptor can be immunoprecipitated as homo- and heterodimers and the detection by BRET of such oligomer in endoplasmic reticulum-enriched fractions suggest that the oligomerization processes take place early during biosynthesis. Treatment with agonists or antagonists did not modify the BRET among any of the vasopressin and oxytocin receptor pairs studied, indicating that the dimerization state of the receptors is not regulated by ligand binding once they have reached the cell surface. Taken together, these results strongly support the notion that GPCR dimerization is a constitutive process.
Assuntos
Receptores de Ocitocina/biossíntese , Receptores de Vasopressinas/biossíntese , Antagonistas dos Receptores de Hormônios Antidiuréticos , Biofísica/métodos , Células Cultivadas , Dimerização , Humanos , Rim/citologia , Rim/efeitos dos fármacos , Rim/embriologia , Ligantes , Medições Luminescentes , Proteínas Luminescentes/genética , Proteínas Luminescentes/metabolismo , Morfolinas/farmacologia , Testes de Precipitina , Receptores de Ocitocina/genética , Receptores de Ocitocina/metabolismo , Receptores de Vasopressinas/agonistas , Receptores de Vasopressinas/genética , Receptores de Vasopressinas/metabolismo , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Transdução de Sinais , Compostos de Espiro/farmacologia , Frações SubcelularesRESUMO
In the present report, we provide for the first time evidence that functional oxytocin receptors (OTRs) are present in human myoblasts obtained from clonal cultures of postnatal satellite cells. First, binding studies performed with a non selective vasopressin (AVP) and oxytocin (OT) radioligand indicated the presence of a single class of binding sites. Second, OTR mRNA was detected by RT-PCR analysis whereas transcripts for AVP V(1a), V(1b) or V(2) receptors (V(1a)R, V(1b)R and V(2)R respectively) were not detected. Third, the presence of functional OTRs was evidenced by showing that agonist substances having a high affinity for the human OTR, namely OT, AVP and [Thr(4)Gly(7)]OT, increased the rate of myoblasts fusion and myotubes formation in the cultures, whereas F180, a V(1a)R selective agonist, and dDAVP, a V(2)R agonist had no significant effect on the fusion process. In addition, we show by RT-PCR and immunocytochemistry that the OT gene is expressed in cultured myoblasts. Taken together, our data suggest that OT may act as a paracrine/autocrine agent that stimulates the fusion of human myoblasts in vitro. In vivo, OT may be involved in the differentiation of human skeletal muscle during postnatal growth, and possibly its regeneration following injury.
Assuntos
Músculo Esquelético/metabolismo , Ocitocina/análogos & derivados , Receptores de Ocitocina/metabolismo , Células Satélites Perineuronais/metabolismo , Arginina Vasopressina/farmacologia , Sítios de Ligação , Ligação Competitiva , Fusão Celular , Células Cultivadas , Humanos , Músculo Esquelético/citologia , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/fisiologia , Oligopeptídeos/metabolismo , Ocitocina/biossíntese , Ocitocina/farmacologia , RNA Mensageiro/metabolismo , Receptores de Ocitocina/genética , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
The fluoresceinyl (Flu) group has been linked by an amide bond to the side chain amino group at position 8 of (a) two oxytocin (OT) antagonists, to give d(CH(2))(5)[Tyr(Me)(2),Thr(4),Orn(8)(5/6C-Flu),Tyr-NH(2)(9)]VT (Orn(8)(5/6C-Flu)OTA) (1) and desGly-NH(2),d(CH(2))(5)[D- Tyr(2),Thr(4),Orn(8)(5/6C-Flu)]VT (2), and (b) eight Lys(8) and Orn(8) analogues of potent OT agonists, to give d[Lys(8)(5/6C-Flu)]VT (3), d[Thr(4),Lys(8)(5/6C-Flu)]VT (4), [HO(1)][Lys(8)(5/6C-Flu)]VT (5), [HO(1)][Thr(4),Lys(8)(5/6C-Flu)]VT (6), d[Orn(8)(5/6C-Flu)]VT (7), d[Thr(4),Orn(8)(5/6C-Flu)]VT (8), [HO(1)][Orn(8)(5/6C-Flu)]VT (9), and [HO(1)][Thr(4),Orn(8)(5/6C-Flu)]VT (10). The tetramethylrhodamyl (Rhm) group was attached to the precursor peptide of 9 to give [HO(1)][Orn(8)(5/6C-Rhm)]VT (11). All 11 fluorescent peptides were evaluated in human OT and vasopressin V(1a) (vasoconstrictor), V(1b) (pituitary), and V(2) (antidiuretic) receptor binding and functional assays. With K(d) = 6.24, 217, >10000, and >10000 nM for the OT, V(1a), V(1b), and V(2) receptors, peptide 1 is a potent and selective fluorescent OT antagonist and may be useful for specifically labeling OT receptors while peptide 2 exhibits low affinities for all the receptors. The fluorescent peptides 3-10 are all very potent agonists for the human OT receptor. They exhibit the following K(d) values (nM) for the human OT, V(1a), V(1b), and V(2) receptors, respectively: (3) 0.29, 57, 124, >10000; (4) 1.8, 25.5, 150, >10000; (5) 0.34, 13.7, 66, nd (not determined); (6) 0.32, 17.3, 53, >10000; (7) 0.25, 107, 393, >10000; (8) 0.40, 30, 282, >10000; (9) 0.18, 12.2, 126, nd; (10) 0.17, 11.8, 87, >1000; (11) 0.092, 7.36, nd, nd. Peptide 7 exhibits both a high affinity and a high selectivity for human OT receptors. Peptides 7 and 11 were utilized to study the internalization of the OT receptor-ligand complex. Preliminary studies indicate that this process is similar to that observed for the vasopressin V(1a) receptor and differs from that observed for vasopressin V(2) receptors. Some or all of the fluorescent OT antagonists and agonists reported here are very promising new fluorescent ligands for labeling cells which express the human OT receptor and are also useful tools to follow endocytosis of the receptor-ligand complex.
Assuntos
Corantes Fluorescentes/síntese química , Oligopeptídeos/síntese química , Receptores de Ocitocina/efeitos dos fármacos , Receptores de Vasopressinas/efeitos dos fármacos , Animais , Antagonistas dos Receptores de Hormônios Antidiuréticos , Ligação Competitiva , Células CHO , Cricetinae , Corantes Fluorescentes/química , Corantes Fluorescentes/farmacologia , Humanos , Fosfatos de Inositol/biossíntese , Ligantes , Oligopeptídeos/química , Oligopeptídeos/farmacologia , Ensaio Radioligante , Receptores de Ocitocina/agonistas , Receptores de Ocitocina/antagonistas & inibidores , Receptores de Vasopressinas/agonistas , Espectrometria de Massas por Ionização por Electrospray , Relação Estrutura-AtividadeRESUMO
In order to produce large amounts of human vasopressin and oxytocin receptors compatible with direct structural biology approaches such as X-ray crystallography, NMR or mass spectrometry, we have expressed these neurohypophysial hormone receptors in Escherichia coli. To facilitate the level of expression, the coding sequence for the V1a vasopressin receptor and the oxytocin receptor were first optimized for bacterial expression. The resulting 'bacterial receptor cDNAs' were then subcloned into pET/T7-driven prokaryotic expression vectors. Different constructs have been prepared: each cDNA was incorporated alone or in fusion with a T7 tag sequence or a glutathione-S-transferase tag sequence at the N-terminus end. Moreover, a 6 x His tag sequence has been added at the C-terminus end for one-step purification of the receptors. Screening of BL21(DE3) and BL21(DE3)pLysS bacterial strains transformed with the different constructions was achieved by Coomassie blue-stained SDS-polyacrylamide gels and by 6 x His antibody Western blotting. Several clones were selected for purification of the receptors. Expression levels of the receptors are now encouraging and will be optimized for further structural and functional studies. Moreover, at the same time, the construction of the bacterial-optimized sequence of the V2 vasopressin receptor and its expression will be performed.
Assuntos
Clonagem Molecular/métodos , Receptores de Ocitocina/química , Receptores de Ocitocina/genética , Receptores de Vasopressinas/química , Receptores de Vasopressinas/genética , Sequência de Aminoácidos , Cristalografia por Raios X , Humanos , Espectroscopia de Ressonância Magnética , Dados de Sequência Molecular , Mutagênese , Estrutura Secundária de Proteína , Proteínas Recombinantes/químicaRESUMO
Inhibitors of JAK2 kinase are emerging as an important treatment modality for myeloproliferative neoplasms (MPN). However, similar to other kinase inhibitors, resistance to JAK2 inhibitors may eventually emerge through a variety of mechanisms. Effective drug combination is one way to enhance therapeutic efficacy and combat resistance against JAK2 inhibitors. To identify potential combination partners for JAK2 compounds in MPN cell lines, we performed pooled shRNA screen targeting 5,000 genes in the presence or absence of JAK2 blockade. One of the top hits identified was MYC, an oncogenic transcription factor that is difficult to inhibit directly, but could be targeted by modulation of upstream regulatory elements such as kinases. We demonstrate herein that PIM kinase inhibitors efficiently suppress MYC protein levels in MPN cell lines. Importantly, overexpression of MYC restores the viability of PIM inhibitor-treated cells, revealing causal relationship between MYC down-regulation and cell growth inhibition by PIM compounds. Combination of various PIM inhibitors with a JAK2 inhibitor results in significant synergistic growth inhibition of multiple MPN cancer cell lines and induction of apoptosis. Mechanistic studies revealed strong downregulation of phosphorylated forms of S6 and 4EBP1 by JAK2/PIM inhibitor combination treatment. Finally, such combination was effective in eradicating in vitro JAK2 inhibitor-resistant MPN clones, where MYC is consistently up-regulated. These findings demonstrate that simultaneous suppression of JAK2 and PIM kinase activity by small molecule inhibitors is more effective than either agent alone in suppressing MPN cell growth. Our data suggest that JAK2 and PIM combination might warrant further investigation for the treatment of JAK2-driven hematologic malignancies.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Janus Quinase 2/antagonistas & inibidores , Transtornos Mieloproliferativos/enzimologia , Proteínas Proto-Oncogênicas c-pim-1/antagonistas & inibidores , Apoptose/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Humanos , Immunoblotting , Inibidores de Proteínas Quinases/farmacologiaRESUMO
An increasing amount of ligand binding data on G protein-coupled receptors (GPCRs) is not compatible with the prediction of the simple mass action law. This may be related to the propensity of most GPCRs, if not all, to oligomerize. Indeed, one of the consequences of receptor oligomerization could be a possible cross-talk between the protomers, which in turn could lead to negative or positive cooperative ligand binding. We prove here that this can be demonstrated experimentally. Saturation, dissociation, and competition binding experiments were performed on vasopressin and oxytocin receptors expressed in Chinese hamster ovary or COS-7 cells. Linear, concave, and convex Scatchard plots were then obtained, depending on the ligand used. Moreover, some competition curves exhibited an increase of the radiotracer binding for low concentrations of competitors, suggesting a cooperative binding process. These data demonstrate that various vasopressin analogs display either positive or negative cooperative binding. Because positive cooperative binding cannot be explained without considering receptor as multivalent, these binding data support the concept of GPCR dimerization process. The results, which are in good accordance with the predictions of previous mathematical models, suggest that binding experiments can be used to probe the existence of receptor dimers.
Assuntos
Receptores Acoplados a Proteínas G/metabolismo , Animais , Arginina Vasopressina/metabolismo , Ligação Competitiva , Células CHO , Células COS , Chlorocebus aethiops , Cricetinae , Cricetulus , Dimerização , Transferência Ressonante de Energia de Fluorescência , Guanosina 5'-O-(3-Tiotrifosfato)/metabolismo , Humanos , Cinética , Ligantes , Modelos Teóricos , Ocitocina/metabolismo , Ligação Proteica , Receptores de Vasopressinas/metabolismo , Fatores de TempoRESUMO
The peptide oxytocin (OT) antagonist atosiban, approved for tocolytic use in Europe (under the tradename Tractocile), represents an important new therapeutic advance for the treatment of premature labor. This paper presents some new peptide OT antagonists which offer promise as superior tocolytics. The solid phase synthesis is reported of four pairs of L and D-2-naphthylalanine (L/D-2Nal) position-2 modified analogs of the following four oxytocin (OT) antagonists: des-9-glycinamide [1-(beta-mercapto-beta,beta-pentamethylene propionic acid), 2-O-methyltyrosine, 4-threonine]ornithine-vasotocin (desGly-NH(2),d(CH(2))(5)[Tyr(Me)(2),Thr(4)]OVT) (A); the Tyr-NH(2) (9) analog of (A), d(CH(2))(5)[Tyr(Me)(2),Thr(4),Tyr-NH(2) (9)]OVT (B); the Eda(9) analog of (A), d(CH(2))(5)[Tyr(Me)(2),Thr(4),Eda(9)]OVT (C); and the retro COCH(2)Ph(4-0H)(10) modified analog of (C), d(CH(2))(5)[Tyr(Me)(2),Thr(4),Eda(9)<-- COCH(2)Ph(4-0H)(10)]OVT (D). The eight new analogs of A-D are (1) desGly-NH(2),d(CH(2))(5)[D-2Nal(2),Thr(4)]OVT, (2) desGly-NH(2),d(CH(2))(5)[2-Nal(2),Thr(4)]OVT, (3) d(CH(2))(5)[D-2Nal(2),Thr(4),Tyr-NH(2) (9)]OVT, (4) d(CH(2))(5)[2Nal(2),Thr(4),Tyr-NH(2) (9)]OVT, (5) d(CH(2))(5)[D-2Nal(2),Thr(4),Eda(9)]OVT, (6) d(CH(2))(5)[2Nal(2),Thr(4),Eda(9)]OVT, (7) d(CH(2))(5)[D-2Nal(2),Thr(4),Eda(9)<-- COCH(2)Ph(4-0H)(10)]OVT, (8) d(CH(2))(5)[2Nal(2),Thr(4),Eda(9)<-- COCH(2)Ph(4-OH)(10)]OVT. Peptides 1-8 were evaluated for agonistic and antagonistic activities in in vitro and in vivo rat bioassays, in rat OT receptor (rOTR) binding assays and in human OT receptor (hOTR) and human vasopressin (VP) vasopressor (V(1a)) receptor (hV(1a)R) binding assays. Also reported are the hOTR and hV(1a)R affinity data for atosiban and for B. None of the eight peptides exhibit oxytocic or vasopressor agonism. Peptides 1-8 exhibit weak antidiuretic agonism (activities in the range 0.014-0.21 U/mg). Peptides 1-6 exhibit potent in vitro (no Mg(2+)) OT antagonism (anti-OT pA(2) values range from 7.63 to 8.08). Peptides 7 and 8 are weaker OT antagonists. Peptides 1-6 are all OT antagonists in vivo (estimated in vivo anti-OT pA(2) values in the range 6.94-7.23). Peptides 1-8 exhibit vasopressor antagonism, anti-V(1a) pA(2) values in the range 5.1-7.65. Peptides 1-8 exhibit high affinities for the rOTR (K(i) values = 0.3-7.8 nM). Peptides 1-4 and B exhibit surprisingly very high affinities for the hOTR; their K(i) values are 0.17, 0.29, 0.07, 0.14 and 0.59 nM, respectively. Peptides 1-4 and B exhibit respectively 449, 263, 1091, 546 and 129 times greater affinity for the hOTR than atosiban (K(i) = 76.4 nM). Peptides 1-4 exhibit high affinities for the hV(1a)R (K(i)s = 1.1 nM, 1.3 nM, 0.19 nM and 0.54 nM, all higher than the hV1(a)R affinities exhibited by atosiban (K(i) = 5.1 nM) and by B (K(i) = 5.26 nM). Because of their strikingly higher affinities for the hOTR than atosiban, peptides 1-4 and B exhibit gains in anti hOT/anti hV(1a) receptor selectivity compared with atosiban of 93, 64, 39, 56 and 127, respectively. These OT antagonists are thus promising candidates for development as potential new tocolytic agents.