scholarly journals Radiosynthesis and preclinical evaluation of a carbon-11 labeled PDE7 inhibitor for PET neuroimaging

2021 ◽  
Author(s):  
Zhiwei Xiao ◽  
Jiyun Sun ◽  
Masayuki Fujinaga ◽  
Huiyi Wei ◽  
Chunyu Zhao ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Specific Binding ◽  
Cell Uptake ◽  
Mammalian Brain ◽  
Intracellular Camp ◽  
Moderate Degree ◽  
Preclinical Evaluation ◽  
Ex Vivo Biodistribution

Background: Dysfunction of cyclic nucleotide phosphodiesterase 7 (PDE7) has been associated with excess intracellular cAMP concentrations, fueling pathogenic processes that are implicated in neurodegenerative disorders. The aim of this study was to develop a suitable PDE7-targeted positron emission tomography (PET) probe that allows non-invasive mapping of PDE7 in the mammalian brain. Methods: Based on a spiro cyclohexane-1,4'-quinazolinone scaffold with known inhibitory properties towards PDE7, we designed and synthesized a methoxy analog that was suitable for carbon-11 labeling. Radiosynthesis was conducted with the respective desmethyl precursor using [11C]MeI. The resulting PET probe, codenamed [11C]26, was evaluated by cell uptake studies, ex vivo biodistribution and radiometabolite studies, as well as in vivo PET experiments in rodents and non-human primates (NHP). Results: Target compound 26 and the corresponding phenolic precursor were synthesized in 2-3 steps with overall yields of 49.5% and 12.4%, respectively. An inhibitory constant (IC50) of 31 nM towards PDE7A was obtained and no significant interaction with other PDE isoforms were observed. [11C]26 was synthesized in high molar activities (170 - 220 GBq/μmol) with radiochemical yields of 34±7%. In vitro cell uptake of [11C]26 was 6-7 fold higher in PDE7B overexpressing cells, as compared to the controls, whereas an in vitro specificity of up to 90% was measured. Ex vivo metabolite studies revealed a high fraction of intact parent in the rat brain (98% at 5 min and 75% at 30 min post injection). Considerable brain penetration was further corroborated by ex vivo biodistribution and PET imaging studies – the latter showing heterogenic brain uptake. While marginal specific binding was observed by PET studies in rodents, a moderate, but dose-dependent, blockade was observed in the NHP brain following pretreatment with non-radioactive 26. Conclusion: In this work, we report on the preclinical evaluation of [11C]26 ( [11C]P7-2104), a PDE7-targeted PET ligand that is based on a spiroquinazolinone scaffold. [11C]26 displayed promising in vitro performance characteristics, a moderate degree of specific binding in PET studies with NHP. Accordingly, [11C]26 will serve as a valuable lead compound for the development of a new arsenal of PDE7-targeted probes with potentially improved in vivo specificity.

scholarly journals Extensive preclinical evaluation of lutetium-177-labeled PSMA-specific tracers for prostate cancer radionuclide therapy

2020 ◽  
Author(s):  
Eline A. M. Ruigrok ◽  
Nicole van Vliet ◽  
Simone U. Dalm ◽  
Erik de Blois ◽  
Dik C. van Gent ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Radionuclide Therapy ◽  
Specific Binding ◽  
Human Kidney ◽  
Careful Evaluation ◽  
Healthy Human ◽  
Binding Characteristics ◽  
Preclinical Evaluation

Abstract Purpose Various radiolabeled prostate-specific membrane antigen (PSMA)–targeting tracers are clinically applied for prostate cancer (PCa) imaging and targeted radionuclide therapy. The PSMA binding affinities, biodistribution, and DNA-damaging capacities of these radiotracers have not yet been compared in detail. A major concern of PSMA-targeting radiotracers is the toxicity in other PSMA-expressing organs, such as the salivary glands, thus demanding careful evaluation of the most optimal and safest radiotracer. In this extensive preclinical study, we evaluated the clinically applied PSMA-targeting small molecule inhibitors DOTA-PSMA-617 (PSMA-617) and DOTAGA-PSMA-I&T (PSMA-I&T) and the PSMA nanobody DOTA-JVZ-007 (JVZ-007) using PSMA-expressing cell lines, a unique set of PCa patient-derived xenografts (PDX) and healthy human tissues. Methods and results In vitro displacement studies on PSMA-expressing cells and cryosections of a PSMA-positive PDX revealed high and specific binding affinity for all three tracers labeled with lutetium-177 with IC50 values in the nanomolar range. Interestingly, [177Lu]Lu-JVZ-007 could not be displaced by PSMA-617 or PSMA-I&T, suggesting that this tracer targets an alternative binding site. Autoradiography assays on cryosections of human salivary and renal tissues revealed [177Lu]Lu-PSMA-617 to have the lowest binding to these healthy organs compared with [177Lu]Lu-PSMA-I&T. In vivo biodistribution assays confirmed the in vitro results with comparable tumor uptake of [177Lu]Lu-PSMA-617 and [177Lu]Lu-PSMA-I&T at all timepoints, resulting in induction of similar levels of DNA double-strand breaks in the tumors. However, [177Lu]Lu-PSMA-I&T demonstrated approximately 40× higher renal uptake at 4 and 8 h post injection resulting in an unfavorable tumor-to-kidney ratio. Conclusion [177Lu]Lu-PSMA-617 has the most favorable biodistribution in mice as well as more favorable binding characteristics in vitro in PSMA-positive cells and human kidney and salivary gland specimens compared with [177Lu]Lu-PSMA-I&T and [177Lu]Lu-JVZ-007. Based on our preclinical evaluation, [177Lu]Lu-PSMA-617 is the best performing tracer to be taken further into clinical evaluation for PSMA-targeted radiotherapeutic development although with careful evaluation of the tracer binding to PSMA-expressing organs.

scholarly journals [68Ga]Ga-DFO-c(RGDyK): Synthesis and Evaluation of Its Potential for Tumor Imaging in Mice

2021 ◽  
Vol 22 (14) ◽  
pp. 7391
Author(s):  
Sona Krajcovicova ◽  
Andrea Daniskova ◽  
Katerina Bendova ◽  
Zbynek Novy ◽  
Miroslav Soural ◽  
...  
Keyword(s):  
Tumor Cell ◽  
Tumor Imaging ◽  
Ex Vivo ◽  
Cell Uptake ◽  
Αvβ3 Integrin ◽  
In Vitro Characterization ◽  
Positron Emission ◽  
Gallium 68

Angiogenesis has a pivotal role in tumor growth and the metastatic process. Molecular imaging was shown to be useful for imaging of tumor-induced angiogenesis. A great variety of radiolabeled peptides have been developed to target αvβ3 integrin, a target structure involved in the tumor-induced angiogenic process. The presented study aimed to synthesize deferoxamine (DFO)-based c(RGD) peptide conjugate for radiolabeling with gallium-68 and perform its basic preclinical characterization including testing of its tumor-imaging potential. DFO-c(RGDyK) was labeled with gallium-68 with high radiochemical purity. In vitro characterization including stability, partition coefficient, protein binding determination, tumor cell uptake assays, and ex vivo biodistribution as well as PET/CT imaging was performed. [68Ga]Ga-DFO-c(RGDyK) showed hydrophilic properties, high stability in PBS and human serum, and specific uptake in U-87 MG and M21 tumor cell lines in vitro and in vivo. We have shown here that [68Ga]Ga-DFO-c(RGDyK) can be used for αvβ3 integrin targeting, allowing imaging of tumor-induced angiogenesis by positron emission tomography.

Aminophylline and progesterone prevent inflammation-induced preterm parturition in the mouse†

2019 ◽  
Vol 101 (4) ◽  
pp. 813-822 ◽  
Author(s):  
Bronwen R Herbert ◽  
Danijela Markovic ◽  
Ektoras Georgiou ◽  
Pei F Lai ◽  
Natasha Singh ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Phosphodiesterase Inhibitor ◽  
Adenosine Monophosphate ◽  
Cytokine Gene Expression ◽  
Intracellular Camp ◽  
Myometrial Cells ◽  
Anti Inflammatory ◽  
Camp Levels

Abstract Although progesterone (P4) supplementation is the most widely used therapy for the prevention of preterm labor (PTL), reports of its clinical efficacy have been conflicting. We have previously shown that the anti-inflammatory effects of P4 can be enhanced by increasing intracellular cyclic adenosine monophosphate (cAMP) levels in primary human myometrial cells. Here, we have examined whether adding aminophylline (Am), a non-specific phosphodiesterase inhibitor that increases intracellular cAMP levels, to P4 might improve its efficacy using in vivo and in vitro models of PTL. In a mouse model of lipopolysaccharide (LPS)-induced PTL, we found that the combination of P4 and Am delayed the onset of LPS-induced PTL, while the same dose of P4 and Am alone had no effect. Pup survival was not improved by either agent alone or in combination. Myometrial prolabor and inflammatory cytokine gene expression was reduced, but the reduction was similar in P4 and P4/Am treated mice. There was no effect of the combination of P4 and Am on an ex vivo assessment of myometrial contractility. In human myometrial cells and myometrial tissue explants, we found that the combination had marked anti-inflammatory effects, reducing cytokine and COX-2 mRNA and protein levels to a greater extent than either agent alone. These data suggest that the combination of P4 and Am has a more potent anti-inflammatory effect than either agent alone and may be an effective combination in women at high-risk of PTL.

scholarly journals AS1411 Nucleolin-Specific Binding Aptamers Reduce Pathological Angiogenesis through Inhibition of Nucleolin Phosphorylation

2021 ◽  
Vol 22 (23) ◽  
pp. 13150
Author(s):  
Emilio Iturriaga-Goyon ◽  
Oscar Vivanco-Rojas ◽  
Fátima Sofía Magaña-Guerrero ◽  
Beatriz Buentello-Volante ◽  
Ilse Castro-Salas ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Specific Binding ◽  
Pediatric Population ◽  
Tube Formation ◽  
In Vitro Models ◽  
In Vivo Model ◽  
Systemic Complications ◽  
Pathological Angiogenesis

Proliferative retinopathies produces an irreversible type of blindness affecting working age and pediatric population of industrialized countries. Despite the good results of anti-VEGF therapy, intraocular and systemic complications are often associated after its intravitreal use, hence novel therapeutic approaches are needed. The aim of the present study is to test the effect of the AS1411, an antiangiogenic nucleolin-binding aptamer, using in vivo, ex vivo and in vitro models of angiogenesis and propose a mechanistic insight. Our results showed that AS1411 significantly inhibited retinal neovascularization in the oxygen induced retinopathy (OIR) in vivo model, as well as inhibited branch formation in the rat aortic ex vivo assay, and, significantly reduced proliferation, cell migration and tube formation in the HUVEC in vitro model. Importantly, phosphorylated NCL protein was significantly abolished in HUVEC in the presence of AS1411 without affecting NFκB phosphorylation and -21 and 221-angiomiRs, suggesting that the antiangiogenic properties of this molecule are partially mediated by a down regulation in NCL phosphorylation. In sum, this new research further supports the NCL role in the molecular etiology of pathological angiogenesis and identifies AS1411 as a novel anti-angiogenic treatment.

scholarly journals Rapid Aldosterone-Mediated Signaling in the DCT Increases Activity of the Thiazide-Sensitive NaCl Cotransporter

2019 ◽  
Vol 30 (8) ◽  
pp. 1454-1470 ◽  
Author(s):  
Lei Cheng ◽  
Søren Brandt Poulsen ◽  
Qi Wu ◽  
Cristina Esteva-Font ◽  
Emma T. B. Olesen ◽  
...  
Keyword(s):  
Cell Biology ◽  
Inositol Phosphate ◽  
Ex Vivo ◽  
Intracellular Camp ◽  
High Potassium ◽  
Inositol Phosphate Accumulation ◽  
Nacl Cotransporter ◽  
Nacl Excretion

BackgroundThe NaCl cotransporter NCC in the kidney distal convoluted tubule (DCT) regulates urinary NaCl excretion and BP. Aldosterone increases NaCl reabsorption via NCC over the long-term by altering gene expression. But the acute effects of aldosterone in the DCT are less well understood.MethodsProteomics, bioinformatics, and cell biology approaches were combined with animal models and gene-targeted mice.ResultsAldosterone significantly increases NCC activity within minutes in vivo or ex vivo. These effects were independent of transcription and translation, but were absent in the presence of high potassium. In vitro, aldosterone rapidly increased intracellular cAMP and inositol phosphate accumulation, and altered phosphorylation of various kinases/kinase substrates within the MAPK/ERK, PI3K/AKT, and cAMP/PKA pathways. Inhibiting GPR30, a membrane-associated receptor, limited aldosterone’s effects on NCC activity ex vivo, and NCC phosphorylation was reduced in GPR30 knockout mice. Phosphoproteomics, network analysis, and in vitro studies determined that aldosterone activates EGFR-dependent signaling. The EGFR immunolocalized to the DCT and EGFR tyrosine kinase inhibition decreased NCC activity ex vivo and in vivo.ConclusionsAldosterone acutely activates NCC to modulate renal NaCl excretion.

scholarly journals IL-27Rα: A Novel Molecular Imaging Marker for Allograft Rejection

2020 ◽  
Vol 21 (4) ◽  
pp. 1315 ◽  
Author(s):  
Shanshan Zhao ◽  
Dai Shi ◽  
Chen Su ◽  
Wen Jiang ◽  
Chao Zhang ◽  
...  
Keyword(s):  
Molecular Imaging ◽  
Graft Rejection ◽  
Ex Vivo ◽  
Inflammatory Diseases ◽  
Whole Body ◽  
Specific Marker ◽  
Post Transplantation ◽  
Ex Vivo Biodistribution

Non-invasively monitoring allogeneic graft rejection with a specific marker is of great importance for prognosis of patients. Recently, data revealed that IL-27Rα was up-regulated in alloreactive CD4+ T cells and participated in inflammatory diseases. Here, we evaluated whether IL-27Rα could be used in monitoring allogeneic graft rejection both in vitro and in vivo. Allogeneic (C57BL/6 donor to BALB/c recipient) and syngeneic (BALB/c both as donor and recipient) skin grafted mouse models were established. The expression of IL-27Rα in grafts was detected. The radio-probe, 125I-anti-IL-27Rα mAb, was prepared. Dynamic whole-body phosphor-autoradiography, ex vivo biodistribution and immunofluorescence staining were performed. The results showed that the highest expression of IL-27Rα was detected in allogeneic grafts on day 10 post transplantation (top period of allorejection). 125I-anti-IL-27Rα mAb was successfully prepared with higher specificity and affinity. Whole-body phosphor-autoradiography showed higher radioactivity accumulation in allogeneic grafts than syngeneic grafts on day 10. The uptake of 125I-anti-IL-27Rα mAb in allogeneic grafts could be almost totally blocked by pre-injection with excess unlabeled anti-IL-27Rα mAb. Interestingly, we found that 125I-anti-IL-27Rα mAb accumulated in allogeneic grafts, along with weaker inflammation earlier on day 6. The high uptake of 125I-anti-IL-27Rα mAb was correlated with the higher infiltrated IL-27Rα positive cells (CD3+/CD68+) in allogeneic grafts. In conclusion, IL-27Rα may be a novel molecular imaging marker to predict allorejection.

scholarly journals Development of [18F]FPy-WL12 as a PD-L1 Specific PET Imaging Peptide

2019 ◽  
Vol 18 ◽  
pp. 153601211985218 ◽  
Author(s):  
Wojciech G. Lesniak ◽  
Ronnie C. Mease ◽  
Samit Chatterjee ◽  
Dhiraj Kumar ◽  
Ala Lisok ◽  
...  
Keyword(s):  
Pet Imaging ◽  
Ex Vivo ◽  
Whole Body ◽  
In Vivo Evaluation ◽  
Positron Emission ◽  
Comprehensive Picture ◽  
Specific Uptake ◽  
Ex Vivo Biodistribution

Expression of programmed cell death ligand 1 (PD-L1) within tumors is an important biomarker for guiding immune checkpoint therapies; however, immunohistochemistry-based methods of detection fail to provide a comprehensive picture of PD-L1 levels in an entire patient. To facilitate quantification of PD-L1 in the whole body, we developed a peptide-based, high-affinity PD-L1 imaging agent labeled with [18F]fluoride for positron emission tomography (PET) imaging. The parent peptide, WL12, and the nonradioactive analog of the radiotracer, 19FPy-WL12, inhibit PD-1/PD-L1 interaction at low nanomolar concentrations (half maximal inhibitory concentration [IC50], 26-32 nM). The radiotracer, [18F]FPy-WL12, was prepared by conjugating 2,3,5,6-tetrafluorophenyl 6-[18F]fluoronicotinate ([18F]FPy-TFP) to WL12 and assessed for specificity in vitro in 6 cancer cell lines with varying PD-L1 expression. The uptake of the radiotracer reflected the PD-L1 expression assessed by flow cytometry. Next, we performed the in vivo evaluation of [18F]FPy-WL12 in mice bearing cancer xenografts by PET imaging, ex vivo biodistribution, and blocking studies. In vivo data demonstrated a PD-L1-specific uptake of [18F]FPy-WL12 in tumors that is reduced in mice receiving a blocking dose. The majority of [18F]FPy-WL12 radioactivity was localized in the tumors, liver, and kidneys indicating the need for optimization of the labeling strategy to improve the in vivo pharmacokinetics of the radiotracer.

Tissue distribution of radioiodinated FAUC113

2006 ◽  
Vol 45 (01) ◽  
pp. 41-48 ◽  
Author(s):  
C. Hocke ◽  
S. Löber ◽  
H. Hübner ◽  
P. Gmeiner ◽  
T. Kuwert ◽  
...  
Keyword(s):  
Frontal Cortex ◽  
Rat Brain ◽  
Specific Activity ◽  
Ex Vivo ◽  
Specific Binding ◽  
Receptor Subtype ◽  
Subtype Selectivity ◽  
Selective Ligand

Summary Aim: Disturbances of the D4 receptor subtype have been implicated in the genesis of a broad range of psychiatric disorders. In order to assess the suitability of a radioiodinated analogue of the D4-selective ligand FAUC 113 for tracer studies in vivo, we investigated the in-vivo stability, biodistribution and brain-uptake of 7-131I-FAUC 113 in Sprague-Dawley rats. Methods: Radiolabelling was carried out with high radiochemical yield and specific activity. After intravenous injection, blood and tissue samples, taken at designated time intervals, were collected for analysis. Analyses of metabolites were performed by radiohplc and radio-tlc. For in-vivo evaluation, sagittal cryo-sections of the rat brain were investigated by in-vitro and exvivo autoradiography on a μ-Imager system. Results: 7-131I-FAUC 113 was rapidly cleared from blood. Highest uptake was observed in kidney (0.603±0.047% ID/g, n=4) and liver (0.357±0.070% ID/g, n=4) at 10 min p.i.; 7-131I-FAUC 113 displayed rapid uptake (0.21-0.26% ID/g) and fast clearance in various brain regions consistent with the determined logP-value of 2.36±0.15 (n=4). In-vivo stability of 7-131I-FAUC 113 was confirmed in the frontal cortex (>95%). Ex-vivo autoradiography revealed a frontal cortex-to-cerebellum ratio of 1.57±0.13 at 10 min p.i. (n=6). Coinjection with L-750667 could not suppress any putative specific binding of 7-131I-FAUC 113. In-vitro autoradiography using authentic 7-iodo-FAUC 113 or L-750667 failed to cause significant displacement of the radioligand. Conclusions: Radioiodinated FAUC 113 does not allow imaging of D4 receptors in the rat brain in vivo nor in vitro. Further work should aim at the development of selective dopamine D4 radioligands with improved tracer characteristics, such as receptor affinity and subtype selectivity, specific activity or blood-brainbarrier permeability.

scholarly journals Formulation of Folate-Modified Raltitrexed-Loaded Nanoparticles for Colorectal Cancer Theranostics

Pharmaceutics ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 133 ◽  
Author(s):  
Justin G. Rosch ◽  
Allison N. DuRoss ◽  
Madeleine R. Landry ◽  
Conroy Sun
Keyword(s):  
Colorectal Cancer ◽  
Near Infrared ◽  
Ex Vivo ◽  
Cell Uptake ◽  
Layer By Layer ◽  
Nir Fluorescence ◽  
Theranostic Applications ◽  
Cancer Theranostics

Multifunctional nanoparticles (NPs) that enable the imaging of drug delivery and facilitate cancer cell uptake are potentially powerful tools in tailoring oncologic treatments. Here we report the development of a layer-by-layer (LbL) formulation of folic acid (FA) and folate antimetabolites that have been well-established for enhanced tumor uptake and as potent chemotherapeutics, respectively. To investigate the uptake of LbL coated NPs, we deposited raltitrexed (RTX) or combined RTX-FA on fluorescent polystyrene NPs. The performance of these NP formulations was evaluated with CT26 murine colorectal cancer (CRC) cells in vitro and in vivo to examine both uptake and cytotoxicity against CRC. Fluorescence microscopy and flow cytometry indicated an increased accumulation of the coated NP formulations versus bare NPs. Ex vivo near-infrared (NIR) fluorescence imaging of major organs suggested the majority of NPs accumulated in the liver, which is typical of a majority of NP formulations. Imaging of the CRC tumors alone showed a higher average fluorescence from NPs accumulated in animals treated with the coated NPs, with the majority of RTX NP-treated animals showing the consistently-highest mean tumoral accumulation. Overall, these results contribute to the development of LbL formulations in CRC theranostic applications.

scholarly journals H-CRRETAWAC-OH, a Lead Structure for the Development of Radiotracer Targeting Integrinα5β1?

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Roland Haubner ◽  
Simone Maschauer ◽  
Jürgen Einsiedel ◽  
Iris E. Eder ◽  
Christine Rangger ◽  
...  
Keyword(s):  
Specific Binding ◽  
Radiochemical Yield ◽  
Human Melanoma ◽  
Cell Uptake ◽  
Preclinical Research ◽  
M Cell ◽  
Biodistribution Studies ◽  
Uptake Studies

Imaging of angiogenic processes is of great interest in preclinical research as well as in clinical settings. The most commonly addressed target structure for imaging angiogenesis is the integrinαvβ3. Here we describe the synthesis and evaluation of [18F]FProp-Cys*-Arg-Arg-Glu-Thr-Ala-Trp-Ala-Cys*-OH, a radiolabelled peptide designed to selectively target the integrinα5β1. Conjugation of 4-nitrophenyl-(RS)-2-[18F]fluoropropionate provided [18F]FProp-Cys*-Arg-Arg-Glu-Thr-Ala-Trp-Ala-Cys*-OH in high radiochemical purity (>95%) and a radiochemical yield of approx. 55%. In vitro evaluation showedα5β1binding affinity in the nanomolar range, whereas affinity toαvβ3andαIIbβ3was >50 μM. Cell uptake studies using human melanoma M21 (αvβ3-positive andα5β1-negative), human melanoma M21-L (αvβ3-negative andα5β1-negative), and human prostate carcinoma DU145 (αvβ3-negative andα5β1-positive) confirmed receptor-specific binding. The radiotracer was stable in human serum and showed low protein binding. Biodistribution studies showed tumour uptake ranging from 2.5 to 3.5% ID/g between 30 and 120 min post-injection. However, blocking studies and studies using mice bearingα5β1-negative M21 tumours did not confirm receptor-specific uptake of [18F]FProp-Cys*-Arg-Arg-Glu-Thr-Ala-Trp-Ala-Cys*-OH, although this radiopeptide revealed high affinity and substantial selectivity toα5β1in vitro. Further experiments are needed to study the in vivo metabolism of this peptide and to develop improved radiopeptide candidates suitable for PET imaging ofα5β1expression in vivo.

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