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1.
Cell Chem Biol ; 2024 Mar 19.
Artigo em Inglês | MEDLINE | ID: mdl-38537632

RESUMO

This study describes the identification and target deconvolution of small molecule inhibitors of oncogenic Yes-associated protein (YAP1)/TAZ activity with potent anti-tumor activity in vivo. A high-throughput screen (HTS) of 3.8 million compounds was conducted using a cellular YAP1/TAZ reporter assay. Target deconvolution studies identified the geranylgeranyltransferase-I (GGTase-I) complex as the direct target of YAP1/TAZ pathway inhibitors. The small molecule inhibitors block the activation of Rho-GTPases, leading to subsequent inactivation of YAP1/TAZ and inhibition of cancer cell proliferation in vitro. Multi-parameter optimization resulted in BAY-593, an in vivo probe with favorable PK properties, which demonstrated anti-tumor activity and blockade of YAP1/TAZ signaling in vivo.

2.
Sci Rep ; 13(1): 20876, 2023 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-38012223

RESUMO

In this work material synergy with high stiffness carbon fiber with ductile high strength polypropylene fiber (Innegra S), (referred to as Innegra, herein) have been evaluated in a range of laminate designs. Both woven and discontinuous carbon fiber have been considered. The discontinuous fibers are based on three-dimensional deposition (3DEP) (referred to as 3DEP, herein) carbon fiber preform process. Eleven (11) variants of Innegra-carbon fiber hybrid laminates were investigated for tensile, flexure, compression, in-plane shear and low velocity impact response. The effect of position of Innegra within the laminate was studied and found to influence strength and stiffness properties. In terms of overall trends, Innegra provides upward of 18% improvement in strain (ductility) to the composite and eliminates brittle fracture of carbon fiber. The moduli trends follow the proportionality of Innegra fiber to carbon fiber plies. However, the strength is controlled by the interface between Innegra and carbon fiber. The primary failure mode in tension and compression is via onset of debonding between Innegra and carbon fiber. The 3DEP carbon fiber constituents provided highest values of in-plane shear indicating that three-dimensional (3D) network of carbon fiber provides higher shear resistance. The Innegra intensive variants exhibited superior energy absorption under low velocity impact, at energy levels 15-60 J. This work provides insight for designers to incorporate Innegra and carbon fiber hybrids in composite structures.

3.
High Educ (Dordr) ; 85(2): 301-323, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-35287377

RESUMO

Online learning is often associated with the alone together paradox that suggests that online students are constantly connected to one another yet feel more alone due to a lack of real social connection. While research has approached this issue from an environmental perspective, some scholars have recently suggested that aspects of online students' complex ecologies, beyond the online program, may also influence the degree students engage socially. This phenomenological study explores the experiences of 10 students enrolled in an online doctoral program in education. In-depth interviews were conducted to discuss how various ecological systems affect students' ability to socially connect in the online program, revealing students reporting feeling apart, but together, rather than alone together. This study encourages online doctoral programs and researchers to take an ecological approach, as opposed to an environmental one, in order to construct a more thorough understanding of the online doctoral student experience.

4.
Molecules ; 26(6)2021 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-33810133

RESUMO

DNA-encoded libraries (DEL) are increasingly being used to identify new starting points for medicinal chemistry in drug discovery. Herein, we discuss the development of methods that allow the conversion of both primary amines and anilines, attached to DNA, to their corresponding azides in excellent yields. The scope of these diazo-transfer reactions was investigated, and a proof-of-concept has been devised to allow for the synthesis of macrocycles on DNA.


Assuntos
DNA , Descoberta de Drogas , Compostos Macrocíclicos/química , Bibliotecas de Moléculas Pequenas
5.
Proc Natl Acad Sci U S A ; 116(7): 2551-2560, 2019 02 12.
Artigo em Inglês | MEDLINE | ID: mdl-30683722

RESUMO

Since the late 1980s, mutations in the RAS genes have been recognized as major oncogenes with a high occurrence rate in human cancers. Such mutations reduce the ability of the small GTPase RAS to hydrolyze GTP, keeping this molecular switch in a constitutively active GTP-bound form that drives, unchecked, oncogenic downstream signaling. One strategy to reduce the levels of active RAS is to target guanine nucleotide exchange factors, which allow RAS to cycle from the inactive GDP-bound state to the active GTP-bound form. Here, we describe the identification of potent and cell-active small-molecule inhibitors which efficiently disrupt the interaction between KRAS and its exchange factor SOS1, a mode of action confirmed by a series of biophysical techniques. The binding sites, mode of action, and selectivity were elucidated using crystal structures of KRASG12C-SOS1, SOS1, and SOS2. By preventing formation of the KRAS-SOS1 complex, these inhibitors block reloading of KRAS with GTP, leading to antiproliferative activity. The final compound 23 (BAY-293) selectively inhibits the KRAS-SOS1 interaction with an IC50 of 21 nM and is a valuable chemical probe for future investigations.


Assuntos
Proteínas Proto-Oncogênicas p21(ras)/antagonistas & inibidores , Proteína SOS1/antagonistas & inibidores , Linhagem Celular , Cristalografia por Raios X , Descoberta de Drogas , Transferência Ressonante de Energia de Fluorescência , Ensaios de Triagem em Larga Escala , Humanos , Ligação Proteica , Proteínas Proto-Oncogênicas p21(ras)/química , Proteínas Proto-Oncogênicas p21(ras)/metabolismo , Proteína SOS1/química , Proteína SOS1/metabolismo , Transdução de Sinais
6.
Mol Imaging Biol ; 18(3): 393-401, 2016 06.
Artigo em Inglês | MEDLINE | ID: mdl-26483088

RESUMO

PURPOSE: Carbon-11- and fluorine-18-labeled choline derivatives are commonly used in prostate cancer imaging in the clinical setting for staging and re-staging of prostate cancer. Due to a limited detection rate of established positron emission tomography (PET) tracers, there is a clinical need for innovative tumor-specific PET compounds addressing new imaging targets. The aim of this study was to compare the properties of [(18)F]Bombesin (BAY 86-4367) as an innovative biomarker for prostate cancer imaging targeting the gastrin-releasing peptide receptor and [(11)C]Choline ([(11)C]CHO) in a human prostate tumor mouse xenograft model by small animal PET/X-ray computed tomography (CT). PROCEDURES: We carried out a dual-tracer small animal PET/CT study comparing [(18)F]Bombesin and [(11)C]CHO. The androgen-independent human prostate tumor cell line PC-3 was implanted subcutaneously in the flanks of nu/nu NMRI mice (n = 10) (PET/CT measurements of two [(11)C]Choline mice could not be analyzed due to technical reasons). [(18)F]Bombesin and [(11)C]CHO PET/CT imaging was performed about 3-4 weeks after the implantation of PC-3 cells on two separate days. After the intravenous tail vein injection of 14 MBq [(18)F]Bombesin and 37 MBq [(11)C]CHO, respectively, a dynamic study over 60 min was acquired in list mode using an Inveon animal PET/CT scanner (Siemens Medical Solutions). The sequence of [(18)F]Bombesin and [(11)C]CHO was randomized. Image analysis was performed using summed images as well as dynamic data. To calculate static and dynamic tumor-to-muscle (T/M), tumor-to-blood (T/B), liver-to-blood (L/B), and kidney-to-blood (K/B) ratios, 4 × 4 × 4 mm(3) volumes of interest (VOIs) of tumor, muscle (thigh), liver, kidney, and blood derived from transversal slices were used. RESULTS: The mean T/M ratio of [(18)F]Bombesin and [(11)C]CHO was 6.54 ± 2.49 and 1.35 ± 0.30, respectively. The mean T/B ratio was 1.83 ± 0.79 for [(18)F]Bombesin and 0.55 ± 0.10 for [(11)C]CHO. The T/M ratio as well as the T/B ratio for [(18)F]Bombesin were significantly higher compared to those for [(11)C]CHO (p < 0.001, respectively). Kidney and liver uptake was statistically significantly lower for [(18)F]Bombesin (K/B 3.41 ± 0.81, L/B 1.99 ± 0.38) compared to [(11)C]CHO [K/B 7.91 ± 1.85 (p < 0.001), L/B 6.27 ± 1.99 (p < 0.001)]. The magnitudes of the time course of T/M and T/B ratios (T/M and T/Bdyn ratios) were statistically significantly different (showing a higher uptake of [(18)F]Bombesin compared to [(11)C]CHO); additionally, also the change of the T/M and T/B ratios over time was significantly different between both tracers in the dynamic analysis (p < 0.001, respectively). Furthermore, there was a statistically significantly different change of the K/B and L/B ratios over time between the two tracers in the dynamic analysis (p = 0.026 and p < 0.001, respectively). CONCLUSIONS: [(18)F]Bombesin (BAY 86-4367) visually and semi-quantitatively outperforms [(11)C]CHO in the PC-3 prostate cancer xenograft model. [(18)F]Bombesin tumor uptake was significantly higher compared to [(11)C]CHO. [(18)F]Bombesin showed better imaging properties compared to the clinically utilized [(11)C]CHO due to a higher tumor uptake as well as a lower liver and kidney uptake.


Assuntos
Bombesina/análogos & derivados , Bombesina/química , Colina/química , Sondas Moleculares/química , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada/métodos , Neoplasias da Próstata/diagnóstico por imagem , Compostos Radiofarmacêuticos/química , Ensaios Antitumorais Modelo de Xenoenxerto , Animais , Bombesina/sangue , Bombesina/farmacocinética , Radioisótopos de Carbono , Linhagem Celular Tumoral , Colina/sangue , Colina/farmacocinética , Radioisótopos de Flúor , Humanos , Masculino , Camundongos , Neoplasias da Próstata/sangue , Neoplasias da Próstata/patologia , Fatores de Tempo
7.
J Nucl Med ; 56(3): 372-8, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25678494

RESUMO

UNLABELLED: The aim of this first-in-man study was to demonstrate the feasibility, safety, and tolerability, as well as provide dosimetric data and evaluate the imaging properties, of the bombesin analogue BAY 864367 for PET/CT in a small group of patients with primary and recurrent prostate cancer (PCa). METHODS: Ten patients with biopsy-proven PCa (5 with primary PCa and 5 with prostate-specific antigen recurrence after radical prostatectomy) were prospectively selected for this exploratory clinical trial with BAY 864367, a new (18)F-labeled bombesin analogue. PET scans were assessed at 6 time points, up to 110 min after intravenous administration of 302 ± 11 MBq of BAY 864367. Imaging results were compared with (18)F-fluorocholine PET/CT scans. Dosimetry was calculated using the OLINDA/EXM software. RESULTS: Three of 5 patients with primary disease showed positive tumor delineation in the prostate, and 2 of 5 patients with biochemical relapse showed a lesion suggestive of recurrence on the BAY 864367 scan. Tumor-to-background ratio averaged 12.9 ± 7.0. The ratio of malignant prostate tissue to normal prostate tissue was 4.4 ± 0.6 in 3 patients with tracer uptake in the primary PCa. Mean effective dose was 4.3 ± 0.3 mSv/patient (range, 3.7-4.9 mSv). CONCLUSION: BAY 864367, a novel (18)F-labeled bombesin tracer, was successfully investigated in a first-in-man clinical trial of PCa and showed favorable dosimetric values. Additionally, the application was safe and well tolerated. The tracer delineated tumors in a subset of patients, demonstrating the potential of gastrin-releasing-peptide receptor imaging.


Assuntos
Bombesina/análogos & derivados , Radioisótopos de Flúor , Neoplasias da Próstata/diagnóstico por imagem , Radiometria/métodos , Administração Intravenosa , Idoso , Algoritmos , Biópsia , Peptídeo Liberador de Gastrina/química , Humanos , Masculino , Pessoa de Meia-Idade , Recidiva Local de Neoplasia/diagnóstico por imagem , Tomografia por Emissão de Pósitrons , Antígeno Prostático Específico/metabolismo , Compostos Radiofarmacêuticos , Software , Tomografia Computadorizada por Raios X
8.
J Nucl Med ; 55(11): 1778-85, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25256060

RESUMO

UNLABELLED: (D)-(18)F-fluoromethyltyrosine (d-(18)F-FMT), or BAY 86-9596, is a novel (18)F-labeled tyrosine derivative rapidly transported by the l-amino acid transporter (LAT-1), with a faster blood pool clearance than the corresponding l-isomer. The aim of this study was to demonstrate the feasibility of tumor detection in patients with non-small cell lung cancer (NSCLC) or head and neck squamous cell cancer (HNSCC) compared with inflammatory and physiologic tissues in direct comparison to (18)F-FDG. METHODS: 18 patients with biopsy-proven NSCLC (n = 10) or HNSCC (n = 8) were included in this Institutional Review Board-approved, prospective multicenter study. All patients underwent (18)F-FDG PET/CT scans within 21 d before d-(18)F-FMT PET/CT. For all patients, safety and outcome data were assessed. RESULTS: No adverse reactions were observed related to d-(18)F-FMT. Fifty-two lesions were (18)F-FDG-positive, and 42 of those were malignant (34 histologically proven and 8 with clinical reference). Thirty-two of the 42 malignant lesions were also d-(18)F-FMT-positive, and 10 lesions had no tracer uptake above the level of the blood pool. Overall there were 34 true-positive, 8 true-negative, 10 false-negative, and only 2 false-positive lesions for d-(18)F-FMT, whereas (18)F-FDG was true-positive in 42 lesions, with 10 false-positive and only 2 false-negative, resulting in a lesion-based detection rate for d-(18)F-FMT and (18)F-FDG of 77% and 95%, respectively, with an accuracy of 78% for both tracers. A high d-(18)F-FMT tumor-to-blood pool ratio had a negative correlation with overall survival (P = 0.050), whereas the (18)F-FDG tumor-to-blood pool ratio did not correlate with overall survival. CONCLUSION: d-(18)F-FMT imaging in patients with NSCLC and HNSCC is safe and feasible. The presented preliminary results suggest a lower sensitivity but higher specificity for d-(18)F-FMT over (18)F-FDG, since there is no d-(18)F-FMT uptake in inflammation. This increased specificity may be particularly beneficial in areas with endemic granulomatous disease and may improve clinical management. Further clinical investigations are needed to determine its clinical value and relevance for the prediction of survival prognosis.


Assuntos
Carcinoma Pulmonar de Células não Pequenas/diagnóstico por imagem , Carcinoma de Células Escamosas/diagnóstico por imagem , Radioisótopos de Flúor/química , Neoplasias de Cabeça e Pescoço/diagnóstico por imagem , Neoplasias Pulmonares/diagnóstico por imagem , Tirosina/análogos & derivados , Tirosina/química , Adulto , Idoso , Biópsia , Carcinoma Pulmonar de Células não Pequenas/diagnóstico , Carcinoma de Células Escamosas/diagnóstico , Reações Falso-Positivas , Feminino , Fluordesoxiglucose F18/química , Neoplasias de Cabeça e Pescoço/diagnóstico , Humanos , Inflamação , Estimativa de Kaplan-Meier , Neoplasias Pulmonares/diagnóstico , Masculino , Pessoa de Meia-Idade , Tomografia por Emissão de Pósitrons , Prognóstico , Estudos Prospectivos , Sensibilidade e Especificidade , Tomografia Computadorizada por Raios X
9.
J Labelled Comp Radiopharm ; 57(3): 164-71, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24453005

RESUMO

The radiosynthesis of [(18)F]fluoropyruvate was investigated using numerous precursors were synthesized from ethyl 2,2-diethoxy-3-hydroxypropanoate (5) containing different leaving groups: mesylate, tosylate, triflate, and nonaflate. These precursors were evaluated for [(18)F]fluoride incorporation with triflate being superior. The subsequent hydrolysis step was investigated, and an acidic hydrolysis was optimized. After establishing suitable purification and formulation methods, the [(18)F]fluoropyruvate could be isolated in ca. 50% d.c. yield. The [(18)F]fluoropyruvate was evaluated in vitro for its uptake into tumor cells using adenocarcinomic human alveolar basal epithelial cells (A549) and unfortunately showed an uptake of approximately 0.1% of the applied dose per 100,000 cells after 30 min. Initial pharmacokinetic properties were assessed in vivo using nude mice showed a high degree of bone uptake from defluorination, which will limit its potential as an imaging agent for metabolic processes.


Assuntos
Radioisótopos de Flúor , Piruvatos/química , Compostos Radiofarmacêuticos/química , Animais , Linhagem Celular Tumoral , Halogenação , Humanos , Camundongos , Camundongos Nus , Tomografia por Emissão de Pósitrons , Piruvatos/síntese química , Radioquímica , Compostos Radiofarmacêuticos/síntese química , Tomografia Computadorizada por Raios X
10.
Eur J Nucl Med Mol Imaging ; 41(1): 89-101, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23955632

RESUMO

PURPOSE: Prostate-specific membrane antigen (PSMA) is a transmembrane protein overexpressed in prostate cancer and is therefore being explored as a biomarker for diagnosing and staging of the disease. Here we report preclinical data on BAY 1075553 (a 9:1 mixture of (2S,4S)- and (2R,4S)-2-[(18)F]fluoro-4-phosphonomethyl-pentanedioic acid), a novel (18)F-labelled small molecule inhibitor of PSMA enzymatic activity, which can be efficiently synthesized from a direct radiolabelling precursor. METHODS: The (18)F-radiolabelled stereoisomers of 2-[(18)F]fluoro-4-(phosphonomethyl)-pentanedioic acid were synthesized from their respective isomerically pure precursors dimethyl 2-{[bis(benzyloxy)phosphoryl]methyl}-4-(tosyloxy)pentanedioate. In vivo positron emission tomography (PET) imaging and biodistribution studies were conducted in mice bearing LNCaP, 22Rv1 and PC-3 tumours. Pharmacokinetic parameters and dosimetry estimates were calculated based on biodistribution studies in rodents. For non-clinical safety assessment (safety pharmacology, toxicology) to support a single-dose human microdose study, off-target effects in vitro, effects on vital organ functions (cardiovascular in dogs, nervous system in rats), mutagenicity screens and an extended single-dose study in rats were conducted with the non-radioactive racemic analogue of BAY 1075553. RESULTS: BAY 1075553 showed high tumour accumulation specific to PSMA-positive tumour-bearing mice and was superior to other stereoisomers tested. Fast clearance of BAY 1075553 resulted overall in low background signals in other organs except for high uptake into kidney and bladder which was mainly caused by renal elimination of BAY 1075553. A modest uptake into bone was observed which decreased over time indicating organ-specific uptake as opposed to defluorination of BAY 1075553 in vivo. Biodistribution studies found highest organ doses for kidneys and the urinary bladder wall resulting in a projected effective dose (ED) in humans of 0.0219 mSv/MBq. Non-clinical safety studies did not show off-target activity, effects on vital organs function or dose-dependent adverse effects. CONCLUSION: BAY 1075553 was identified as a promising PET tracer for PSMA-positive prostate tumours in preclinical studies. BAY 1075553 can be produced using a robust, direct radiosynthesis procedure. Pharmacokinetic, toxicology and safety pharmacology studies support the application of BAY 1075553 in a first-in-man microdose study with single i.v. administration.


Assuntos
Radioisótopos de Flúor , Glutamato Carboxipeptidase II/antagonistas & inibidores , Glutaratos , Organofosfonatos , Tomografia por Emissão de Pósitrons/métodos , Neoplasias da Próstata/diagnóstico por imagem , Compostos Radiofarmacêuticos , Animais , Antígenos de Superfície , Cães , Feminino , Glutaratos/efeitos adversos , Glutaratos/farmacocinética , Glutaratos/farmacologia , Humanos , Marcação por Isótopo , Masculino , Camundongos , Organofosfonatos/efeitos adversos , Organofosfonatos/farmacocinética , Organofosfonatos/farmacologia , Traçadores Radioativos , Radioquímica , Compostos Radiofarmacêuticos/efeitos adversos , Compostos Radiofarmacêuticos/farmacocinética , Compostos Radiofarmacêuticos/farmacologia , Ratos , Segurança , Estereoisomerismo
11.
J Med Chem ; 56(19): 7552-63, 2013 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-23992105

RESUMO

Silicon-containing prosthetic groups have been conjugated to peptides to allow for a single-step labeling with (18)F radioisotope. The fairly lipophilic di-tert-butylphenylsilane building block contributes unfavorably to the pharmacokinetic profile of bombesin conjugates. In this article, theoretical and experimental studies toward the development of more hydrophilic silicon-based building blocks are presented. Density functional theory calculations were used to predict the hydrolytic stability of di-tert-butylfluorosilanes 2-23 with the aim to improve the in vivo properties of (18)F-labeled silicon-containing biomolecules. As a further step toward improving the pharmacokinetic profile, hydrophilic linkers were introduced between the lipophilic di-tert-butylphenylsilane building block and the bombesin congeners. Increased tumor uptake was shown with two of these peptides in xenograft-bearing mice using positron emission tomography and biodistribution studies. The introduction of a hydrophilic linker is thus a viable approach to improve the tumor uptake of (18)F-labeled silicon-bombesin conjugates.


Assuntos
Bombesina/análogos & derivados , Bombesina/química , Peptídeos/química , Compostos Radiofarmacêuticos/química , Silanos/química , Animais , Bombesina/farmacocinética , Estabilidade de Medicamentos , Radioisótopos de Flúor , Xenoenxertos , Humanos , Hidrólise , Interações Hidrofóbicas e Hidrofílicas , Marcação por Isótopo , Masculino , Camundongos , Camundongos Nus , Neoplasias Experimentais/diagnóstico por imagem , Neoplasias Experimentais/metabolismo , Tomografia por Emissão de Pósitrons , Teoria Quântica , Compostos Radiofarmacêuticos/farmacocinética , Receptores da Bombesina/metabolismo , Silanos/farmacocinética , Relação Estrutura-Atividade , Distribuição Tecidual
12.
PLoS One ; 8(8): e69529, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23936336

RESUMO

Inflammation is a pathophysiological hallmark of many diseases of the brain. Specific imaging of cells and molecules that contribute to cerebral inflammation is therefore highly desirable, both for research and in clinical application. The 18 kDa translocator protein (TSPO) has been established as a suitable target for the detection of activated microglia/macrophages. A number of novel TSPO ligands have been developed recently. Here, we evaluated the high affinity TSPO ligand DPA-714 as a marker of brain inflammation in two independent animal models. For the first time, the specificity of radiolabeled DPA-714 for activated microglia/macrophages was studied in a rat model of epilepsy (induced using Kainic acid) and in a mouse model of stroke (transient middle cerebral artery occlusion, tMCAO) using high-resolution autoradiography and immunohistochemistry. Additionally, cold-compound blocking experiments were performed and changes in blood-brain barrier (BBB) permeability were determined. Target-to-background ratios of 2 and 3 were achieved in lesioned vs. unaffected brain tissue in the epilepsy and tMCAO models, respectively. In both models, ligand uptake into the lesion corresponded well with the extent of Ox42- or Iba1-immunoreactive activated microglia/macrophages. In the epilepsy model, ligand uptake was almost completely blocked by pre-injection of DPA-714 and FEDAA1106, another high-affinity TSPO ligand. Ligand uptake was independent of the degree of BBB opening and lesion size in the stroke model. We provide further strong evidence that DPA-714 is a specific ligand to image activated microglia/macrophages in experimental models of brain inflammation.


Assuntos
Proteínas de Transporte/metabolismo , Modelos Animais de Doenças , Epilepsia/complicações , Inflamação/diagnóstico , Pirazóis , Pirimidinas , Receptores de GABA-A/metabolismo , Receptores de GABA/metabolismo , Acidente Vascular Cerebral/complicações , Animais , Autorradiografia , Barreira Hematoencefálica , Células Cultivadas , Epilepsia/induzido quimicamente , Epilepsia/patologia , Radioisótopos de Flúor , Técnicas Imunoenzimáticas , Inflamação/etiologia , Inflamação/metabolismo , Ácido Caínico/toxicidade , Macrófagos/imunologia , Macrófagos/metabolismo , Macrófagos/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Microglia/imunologia , Microglia/metabolismo , Microglia/patologia , Tomografia por Emissão de Pósitrons , Pirazóis/metabolismo , Pirimidinas/metabolismo , Compostos Radiofarmacêuticos , Ratos , Ratos Sprague-Dawley , Acidente Vascular Cerebral/induzido quimicamente , Acidente Vascular Cerebral/patologia
13.
Bioorg Med Chem ; 21(3): 643-52, 2013 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-23290251

RESUMO

The [(18)F]fluorocyclobutyl group has the potential to be a metabolically stable prosthetic group for PET tracers. The synthesis of the radiolabeling precursor cis-cyclobutane-1,3-diyl bis(toluene-4-sulfonate) 8 was obtained from epibromohydrin in 7 steps (2% overall yield). The radiolabeling of this precursor 8 and its conjugation to L-tyrosine as a model system was successfully achieved to give the new non-natural amino acid 3-[(18)F]fluorocyclobutyl-L-tyrosine (L-3-[(18)F]FCBT) [(18)F]17 in 8% decay-corrected yield from the non-carrier-added [(18)F]fluoride. L-3-[(18)F]FCBT was investigated in vitro in different cancer cell lines to determine the uptake and stability. The tracer [(18)F]17 showed a time dependent uptake into different tumor cell lines (A549, NCI-H460, DU145) with the best uptake of 5.8% injected dose per 5×10(5) cells after 30min in human lung carcinoma cells A549. The stability of L-3-[(18)F]FCBT in human and rat plasma and the stability of the non-radioactive L-3-FCBT in rat hepatocytes were both found to be excellent. These results show that the non-natural amino acid L-3-[(18)F]FCBT is a promising metabolically stable radiotracer for positron emission tomography.


Assuntos
Ciclobutanos/farmacocinética , Radioisótopos de Flúor/farmacocinética , Compostos Radiofarmacêuticos/farmacocinética , Tirosina/farmacocinética , Animais , Linhagem Celular Tumoral , Ciclobutanos/síntese química , Ciclobutanos/química , Radioisótopos de Flúor/química , Hepatócitos/química , Humanos , Modelos Moleculares , Estrutura Molecular , Compostos Radiofarmacêuticos/síntese química , Compostos Radiofarmacêuticos/química , Ratos , Ratos Wistar , Tirosina/química
14.
J Med Chem ; 55(22): 9510-20, 2012 Nov 26.
Artigo em Inglês | MEDLINE | ID: mdl-23025786

RESUMO

For prostate cancer, prostate specific membrane antigen (PSMA) has been identified as a diagnostic and therapeutic target. Fluorinated derivatives of 2-(phosphonomethyl)pentanedioic acid were designed and synthesized to explore whether this fluorine-substituent is tolerated in the pentanedioic acid moiety that is common to almost all PSMA targeting small molecule inhibitors. The binding affinities of the racemic and individual stereoisomers of 2-fluoro-4-(phosphonomethyl)pentanedioic acid were determined and showed that the introduction of fluorine was well tolerated. The radiosynthesis of the analogous 2-[(18)F]fluoro-4-(phosphonomethyl)pentanedioic acid was developed and evaluated in vivo with the PSMA positive LNCaP human prostate cancer cell. The biological results demonstrated specific binding of the tracer to PSMA positive tumors in mice. These results warrant the further evaluation of this class of compounds as radiolabeled tracers for the detection and staging of prostate cancer.


Assuntos
Diagnóstico por Imagem , Glutamato Carboxipeptidase II/antagonistas & inibidores , Compostos Organofosforados/química , Neoplasias da Próstata/diagnóstico , Compostos Radiofarmacêuticos , Animais , Linhagem Celular Tumoral , Humanos , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Modelos Químicos , Imagem Multimodal , Tomografia por Emissão de Pósitrons , Neoplasias da Próstata/metabolismo , Radioquímica , Estereoisomerismo , Distribuição Tecidual , Tomografia Computadorizada por Raios X , Células Tumorais Cultivadas , Ensaios Antitumorais Modelo de Xenoenxerto
15.
J Nucl Med ; 52(2): 270-8, 2011 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-21233180

RESUMO

UNLABELLED: Bombesin is a peptide exhibiting high affinity for the gastrin-releasing peptide receptor (GRPr), which is highly overexpressed on prostate cancer cells. In the present study, we developed an (18)F-labeled bombesin analog, (18)F-BAY 86-4367, which is currently being clinically tested for use in PET of prostate cancer. METHODS: In vitro pharmacologic studies were performed to characterize the nonradioactive ((19)F) standard of the bombesin analog for binding affinity and selectivity for GRPr. The stability of (18)F-BAY 86-4367 was determined in murine and human plasma. In vivo, the tumor-targeting potential and pharmacokinetic profile of the (18)F tracer were analyzed with biodistribution experiments and PET studies of prostate tumor-bearing mice. RESULTS: The nonradioactive ((19)F) standard of the bombesin analog showed subnanomolar and GRPr-selective binding affinity. The stability of the tracer in murine and human plasma was found to be high. In 2 prostate cancer xenograft models (PC-3 and LNCaP), (18)F-BAY 86-4367 showed more specific and effective GRPr-based targeting in vivo than the benchmark radiotracers (18)F-fluoroethylcholine and (18)F-FDG. In addition, rapid tumor targeting and fast renal excretion (∼70%) and hepatobiliary excretion (∼10%) were identified in both xenograft models. Furthermore, PET studies provided clear and specific visualization of PC-3 tumors in mice. CONCLUSION: Favorable preclinical data showing specific and effective tumor targeting by (18)F-BAY 86-4367 suggest that a clinical trial be undertaken to test its diagnostic utility in PET for prostate carcinoma patients.


Assuntos
Bombesina/análogos & derivados , Neoplasias da Próstata/diagnóstico por imagem , Neoplasias da Próstata/metabolismo , Compostos Radiofarmacêuticos , Receptores da Bombesina/metabolismo , Animais , Ligação Competitiva/efeitos dos fármacos , Bombesina/química , Bombesina/farmacocinética , Linhagem Celular , Ácido Cisteico/química , Estabilidade de Medicamentos , Radioisótopos de Flúor , Humanos , Indicadores e Reagentes , Marcação por Isótopo , Masculino , Camundongos , Camundongos Nus , Transplante de Neoplasias , Cintilografia , Compostos Radiofarmacêuticos/química , Compostos Radiofarmacêuticos/farmacocinética , Receptores da Bombesina/genética , Distribuição Tecidual
16.
Eur J Nucl Med Mol Imaging ; 38(1): 97-107, 2011 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-20717822

RESUMO

PURPOSE: Radiolabelled somatostatin-based antagonists show a higher uptake in tumour-bearing mouse models than agonists of similar or even distinctly higher receptor affinity. Very similar results were obtained with another family of G protein-coupled receptor ligands, the bombesin family. We describe a new conjugate, RM2, with the chelator DOTA coupled to D-Phe-Gln-Trp-Ala-Val-Gly-His-Sta-Leu-NH(2) via the cationic spacer 4-amino-1-carboxymethyl-piperidine for labelling with radiometals such as (111)In and (68)Ga. METHODS: RM2 was synthesized on a solid support and evaluated in vitro in PC-3 cells. IC(50) and K(d) values were determined. The antagonist potency was evaluated by immunofluorescence-based internalization and Ca(2+) mobilization assays. Biodistribution studies were performed in PC-3 and LNCaP tumour-bearing mice with (111)In-RM2 and (68)Ga-RM2, respectively. PET/CT studies were performed on PC-3 and LNCaP tumour-bearing nude mice with (68)Ga-RM2. RESULTS: RM2 and (111)In-RM2 are high-affinity and selective ligands for the GRP receptor (7.7 ± 3.3 nmol/l for RM2; 9.3 ± 3.3 nmol/l for (nat)In-RM2). The potent antagonistic properties were confirmed by an immunofluorescence-based internalization and Ca(2+) mobilization assays. (68)Ga- and (111)In-RM2 showed high and specific uptake in both the tumour and the pancreas. Uptake in the tumour remained high (15.2 ± 4.8%IA/g at 1 h; 11.7 ± 2.4%IA/g at 4 h), whereas a relatively fast washout from the pancreas and the other abdominal organs was observed. Uptake in the pancreas decreased rapidly from 22.6 ± 4.7%IA/g at 1 h to 1.5 ± 0.5%IA/g at 4 h. CONCLUSION: RM2 was shown to be a potent GRPr antagonist. Pharmacokinetics and imaging studies indicate that (111)In-RM2 and (68)Ga-RM2 are ideal candidates for clinical SPECT and PET studies.


Assuntos
Bombesina/antagonistas & inibidores , Descoberta de Drogas , Compostos Heterocíclicos com 1 Anel/química , Oligopeptídeos/metabolismo , Oligopeptídeos/farmacologia , Neoplasias da Próstata/metabolismo , Receptores da Bombesina/metabolismo , Animais , Linhagem Celular Tumoral , Feminino , Células HEK293 , Humanos , Masculino , Camundongos , Oligopeptídeos/química , Oligopeptídeos/farmacocinética , Neoplasias da Próstata/patologia , Transporte Proteico , Ensaios Antitumorais Modelo de Xenoenxerto
17.
J Med Chem ; 54(1): 406-10, 2011 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-21128591

RESUMO

There is a high demand for tumor specific PET tracers in oncology imaging. Besides glucose, certain amino acids also serve as energy sources and anabolic precursors for tumors. Therefore, (18)F-labeled amino acids are interesting probes for tumor specific PET imaging. As glutamine and glutamate play a key role in the adapted intermediary metabolism of tumors, the radiosynthesis of 4-[(18)F]fluoro l-glutamic acid (BAY 85-8050) as a new specific PET tracer was established. Cell-uptake studies revealed specific tumor cell accumulation.


Assuntos
Glutamatos/síntese química , Compostos Radiofarmacêuticos/síntese química , Linhagem Celular Tumoral , Radioisótopos de Flúor , Glutamatos/química , Glutamatos/metabolismo , Humanos , Marcação por Isótopo , Tomografia por Emissão de Pósitrons , Compostos Radiofarmacêuticos/química , Compostos Radiofarmacêuticos/metabolismo , Estereoisomerismo
18.
Bioconjug Chem ; 21(10): 1864-71, 2010 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-20857927

RESUMO

The gastrin-releasing peptide receptor (GRPR) is overexpressed on a number of human tumors and has been targeted with radiolabeled bombesin analogues for the diagnosis and therapy of these cancers. Seven bombesin analogues containing various linkers and peptide sequences were designed, synthesized, radiolabeled with (18)F, and characterized in vitro and in vivo as potential PET imaging agents. Binding studies displayed nanomolar binding affinities toward human GRPR for all synthesized bombesin analogues. Two high-affinity peptide candidates 6b (K(i) = 0.7 nM) and 7b (K(i) = 0.1 nM) were chosen for further in vivo evaluation. Both tracers revealed specific uptake in GRPR-expressing PC-3 tumors and the pancreas. Compared to [(18)F]6b, compound [(18)F]7b was characterized by superior tumor uptake, higher specificity of tracer uptake, and more favorable tumor-to-nontarget ratios. In vivo PET imaging allowed for the visualization of PC-3 tumor in nude mice suggesting that [(18)F]7b is a promising PET tracer candidate for the diagnosis of GRPR-positive tumors in humans.


Assuntos
Bombesina/análogos & derivados , Bombesina/metabolismo , Radioisótopos de Flúor , Neoplasias da Próstata/metabolismo , Neoplasias da Próstata/patologia , Receptores da Bombesina/metabolismo , Animais , Bombesina/química , Bombesina/farmacocinética , Linhagem Celular Tumoral , Humanos , Masculino , Camundongos , Tomografia por Emissão de Pósitrons , Neoplasias da Próstata/diagnóstico por imagem , Ensaios Antitumorais Modelo de Xenoenxerto
19.
J Nucl Med ; 51(10): 1632-6, 2010 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-20847178

RESUMO

UNLABELLED: The presence and localization of metastatic bone lesions is important for the staging of the disease and subsequent treatment decisions. Detecting tumor cells would have additional value over the current indirect bone scintigraphy method for detecting areas of elevated skeletal metabolic activity. d-(18)F-fluoromethyl tyrosine (d-(18)F-FMT) has recently shown good uptake and fast elimination, resulting in good tumor-to-background ratios. The potential of d-(18)F-FMT for imaging bone metastases has been investigated. METHODS: 786-O/luciferase human renal adenocarcinoma cells were injected intracardially, resulting in the formation of bone metastases in mice. Small-animal PET was performed 51 and 65 d after tumor cell inoculation. RESULTS: d-(18)F-FMT showed specific uptake in the bone metastases, giving excellent images with a little background in the pancreas. All imaged metastases were histologically confirmed. A bone scan with (18)F-fluoride showed elevated skeletal metabolic activity in the areas of osteolytic lesions. CONCLUSION: d-(18)F-FMT is a useful PET tracer for the detection of bone metastases and should be evaluated in the clinical setting.


Assuntos
Neoplasias Ósseas/diagnóstico por imagem , Neoplasias Ósseas/secundário , Modelos Animais de Doenças , Tirosina/análogos & derivados , Animais , Linhagem Celular Tumoral , Feminino , Humanos , Camundongos , Camundongos Nus , Cintilografia , Compostos Radiofarmacêuticos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
20.
Bioconjug Chem ; 20(12): 2254-61, 2009 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-19921791

RESUMO

Methods for the radiolabeling molecules of interest with [18F]-fluoride need to be rapid, convenient, and efficient. Numerous [18F]-labeled prosthetic groups, e.g., N-succinimidyl 4 [18F]-fluorobenzoate ([18F]-SFB), 4-azidophenacyl-[18F]-fluoride ([18F]-APF), and 1-(3-(2-[18F]fluoropyridin-3-yloxy)propyl)pyrrole-2,5-dione ([18F]-FpyMe), for conjugating to biomolecules have been developed. As the synthesis of these prosthetic groups usually requires multistep procedures, there is still a need for direct methods for the nucleophilic [18F]-fluorination of biomolecules. We report here on the development of a procedure based on the trimethylammonium (TMA) leaving group attached to an aromatic ring and activated with different electron-withdrawing groups (EWGs). A series of model compounds containing different electron-withdrawing substituents, a trimethylammonium leaving group, and carboxylic functionality for subsequent coupling to peptides were designed and synthesized. The optimal model compound, 2-cyano-4-(methoxycarbonyl)-N,N,N-trimethylbenzenaminium trifluoromethanesulfonate, was converted to carboxylic acid and coupled to peptides. The results of the one-step [18F]-fluorination of tetrapeptides and bombesin peptides show that the direct 18F-labeling of peptides is feasible under mild conditions and in good radiochemical yields.


Assuntos
Derivados de Benzeno/química , Peptídeos/química , Compostos de Trimetil Amônio/química , Radioisótopos de Flúor/química , Estrutura Molecular , Estereoisomerismo
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