Synthesis, Characterization and In Vitro Evaluation of Hybrid Monomeric Peptides Suited for Multimodal Imaging by PET/OI: Extending the Concept of Charge–Cell Binding Correlation

In the context of hybrid multimodal imaging agents for gastrin releasing peptide receptor (GRPR) targeting, a correlation between the net charge and the receptor affinity of the agents was recently found. In particular, a decrease in in vitro GRPR binding affinity was observed in case of an increasing number of negative charges for dually labeled GRPR–specific peptide dimers suited for positron emission tomography and optical imaging (PET/OI). This adverse influence of anionic charges could be in part compensated by a higher valency of peptide multimerization. However, it remains unknown whether this adverse effect of anionic charges is limited to peptide multimers or if it is also found or even more pronounced when GRPR–specific peptide monomers are dually labeled with fluorescent dye and chelating agent/radionuclide. Moreover, it would be important to know if this effect is limited to GRPR–specific agents only or if these observations also apply to other dually labeled peptides binding to other receptor types. To address these questions, we synthesized hybrid labels, comprising a chelator, different fluorescent dyes carrying different net charges and a functional group for bioconjugation and introduced them into different peptides, specifically targeting the GRPR, the melanocortin–1 receptor (MC1R) and integrin αvβ3. The synthesized conjugates were evaluated with regard to their chemical, radiochemical, photophysical and receptor affinity properties. It was found that neither the 68Ga–radiolabeling nor the fluorescence characteristics of the dyes were altered by the conjugation of the MIUs to the peptides. Further, it was confirmed that the net number of anionic charges has a negative effect on the GRPR–binding affinity of the GRPR–targeting MIU–peptide monomer conjugates and that this same effect was also found to the same extent for the other receptor systems studied.

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Synthesis and Evaluation of [18F]FEtLos and [18F]AMBF3Los as Novel 18F-Labelled Losartan Derivatives for Molecular Imaging of Angiotensin II Type 1 Receptors

Molecules ◽

10.3390/molecules25081872 ◽

2020 ◽

Vol 25 (8) ◽

pp. 1872

Author(s):

Martha Sahylí Ortega Pijeira ◽

Paulo Sérgio Gonçalves Nunes ◽

Sofia Nascimento dos Santos ◽

Zhengxing Zhang ◽

Arian Pérez Nario ◽

...

Keyword(s):

Angiotensin Ii ◽

Binding Affinity ◽

Renin Angiotensin System ◽

Prosthetic Group ◽

Positron Emission ◽

One Step ◽

Group 2

Losartan is widely used in clinics to treat cardiovascular related diseases by selectively blocking the angiotensin II type 1 receptors (AT1Rs), which regulate the renin-angiotensin system (RAS). Therefore, monitoring the physiological and pathological biodistribution of AT1R using positron emission tomography (PET) might be a valuable tool to assess the functionality of RAS. Herein, we describe the synthesis and characterization of two novel losartan derivatives PET tracers, [18F]fluoroethyl-losartan ([18F]FEtLos) and [18F]ammoniomethyltrifluoroborate-losartan ([18F]AMBF3Los). [18F]FEtLos was radiolabeled by 18F-fluoroalkylation of losartan potassium using the prosthetic group 2-[18F]fluoroethyl tosylate; whereas [18F]AMBF3Los was prepared following an one-step 18F-19F isotopic exchange reaction, in an overall yield of 2.7 ± 0.9% and 11 ± 4%, respectively, with high radiochemical purity (>95%). Binding competition assays in AT1R-expressing membranes showed that AMBF3Los presented an almost equivalent binding affinity (Ki 7.9 nM) as the cold reference Losartan (Ki 1.5 nM), unlike FEtLos (Ki 2000 nM). In vitro and in vivo assays showed that [18F]AMBF3Los displayed a good binding affinity for AT1R-overexpressing CHO cells and was able to specifically bind to renal AT1R. Hence, our data demonstrate [18F]AMBF3Los as a new tool for PET imaging of AT1R with possible applications for the diagnosis of cardiovascular, inflammatory and cancer diseases.

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A Novel PET Imaging Using64Cu-Labeled Monoclonal Antibody against Mesothelin Commonly Expressed on Cancer Cells

Journal of Immunology Research ◽

10.1155/2015/268172 ◽

2015 ◽

Vol 2015 ◽

pp. 1-15 ◽

Cited By ~ 15

Author(s):

Kazuko Kobayashi ◽

Takanori Sasaki ◽

Fumiaki Takenaka ◽

Hiromasa Yakushiji ◽

Yoshihiro Fujii ◽

...

Keyword(s):

Monoclonal Antibody ◽

Cancer Cells ◽

Pet Imaging ◽

Ex Vivo ◽

Chelating Agent ◽

Pancreatic Cancer Cells ◽

Positron Emission ◽

Wide Range

Mesothelin (MSLN) is a 40-kDa cell differentiation-associated glycoprotein appearing with carcinogenesis and is highly expressed in many human cancers, including the majority of pancreatic adenocarcinomas, ovarian cancers, and mesotheliomas, while its expression in normal tissue is limited to mesothelial cells lining the pleura, pericardium, and peritoneum. Clone 11-25 is a murine hybridoma secreting monoclonal antibody (mAb) against human MSLN. In this study, we applied the 11-25 mAb toin vivoimaging to detect MSLN-expressing tumors. Inin vitroandex vivoimmunochemical studies, we demonstrated specificity of 11-25 mAb to membranous MSLN expressed on several pancreatic cancer cells. We showed the accumulation of Alexa Fluor 750-labeled 11-25 mAb in MSLN-expressing tumor xenografts in athymic nude mice. Then, 11-25 mAb was labeled with64Cu via a chelating agent DOTA and was used in bothin vitrocell binding assay andin vivopositron emission tomography (PET) imaging in the tumor-bearing mice. We confirmed that64Cu-labeled 11-25 mAb highly accumulated in MSLN-expressing tumors as compared to MSLN-negative ones. The64Cu-labeled 11-25 mAb is potentially useful as a PET probe capable of being used for wide range of tumors, rather than18F-FDG that occasionally provides nonspecific accumulation into the inflammatory lesions.

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Synthesis of a DOTA-C-glyco bifunctional chelating agent and preliminary in vitro and in vivo study of [68Ga]Ga-DOTA-C-glyco-RGD

RSC Advances ◽

10.1039/d0ra09274f ◽

2021 ◽

Vol 11 (13) ◽

pp. 7672-7681

Author(s):

Floriane Mangin ◽

Charlotte Collet ◽

Valérie Jouan-Hureaux ◽

Fatiha Maskali ◽

Emilie Roeder ◽

...

Keyword(s):

Positron Emission Tomography ◽

Cancer Diagnosis ◽

Positron Emission Tomography Imaging ◽

Chelating Agent ◽

Emission Tomography ◽

Tomography Imaging ◽

Bifunctional Chelating Agent ◽

Positron Emission

A carbohydrate containing [68Ga]Ga-DOTA-RGD tracer was designed and demonstrated promising results for cancer diagnosis by positron emission tomography imaging.

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Computational Evaluation and In Vitro Validation of New Epidermal Growth Factor Receptor Inhibitors

Current Topics in Medicinal Chemistry ◽

10.2174/1568026620666200603122726 ◽

2020 ◽

Vol 20 (18) ◽

pp. 1628-1639

Author(s):

Sergi Gómez-Ganau ◽

Josefa Castillo ◽

Andrés Cervantes ◽

Jesus Vicente de Julián-Ortiz ◽

Rafael Gozalbes

Keyword(s):

Cell Proliferation ◽

Epidermal Growth Factor Receptor ◽

Growth Factor ◽

Epidermal Growth Factor ◽

Binding Affinity ◽

Cell Lines ◽

Growth Factor Receptor ◽

Significant Activity ◽

Epidermal Growth

Background: The Epidermal Growth Factor Receptor (EGFR) is a transmembrane protein that acts as a receptor of extracellular protein ligands of the epidermal growth factor (EGF/ErbB) family. It has been shown that EGFR is overexpressed by many tumours and correlates with poor prognosis. Therefore, EGFR can be considered as a very interesting therapeutic target for the treatment of a large variety of cancers such as lung, ovarian, endometrial, gastric, bladder and breast cancers, cervical adenocarcinoma, malignant melanoma and glioblastoma. Methods: We have followed a structure-based virtual screening (SBVS) procedure with a library composed of several commercial collections of chemicals (615,462 compounds in total) and the 3D structure of EGFR obtained from the Protein Data Bank (PDB code: 1M17). The docking results from this campaign were then ranked according to the theoretical binding affinity of these molecules to EGFR, and compared with the binding affinity of erlotinib, a well-known EGFR inhibitor. A total of 23 top-rated commercial compounds displaying potential binding affinities similar or even better than erlotinib were selected for experimental evaluation. In vitro assays in different cell lines were performed. A preliminary test was carried out with a simple and standard quick cell proliferation assay kit, and six compounds showed significant activity when compared to positive control. Then, viability and cell proliferation of these compounds were further tested using a protocol based on propidium iodide (PI) and flow cytometry in HCT116, Caco-2 and H358 cell lines. Results: The whole six compounds displayed good effects when compared with erlotinib at 30 μM. When reducing the concentration to 10μM, the activity of the 6 compounds depends on the cell line used: the six compounds showed inhibitory activity with HCT116, two compounds showed inhibition with Caco-2, and three compounds showed inhibitory effects with H358. At 2 μM, one compound showed inhibiting effects close to those from erlotinib. Conclusion: Therefore, these compounds could be considered as potential primary hits, acting as promising starting points to expand the therapeutic options against a wide range of cancers.

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Synthesis, Antimicrobial Evaluation and Docking Study of Novel Thiosemicarbazone clubbed with 1,2,3-Triazoles

Current Bioactive Compounds ◽

10.2174/1573407216999200911121853 ◽

2020 ◽

Vol 16 ◽

Author(s):

Adinath D. Badar ◽

Shubham M. Sulakhe ◽

Mahesh B. Muluk ◽

Naziya N. M. A. Rehman ◽

Prashant P. Dixit ◽

...

Keyword(s):

Binding Affinity ◽

Biological Activities ◽

Dna Gyrase ◽

Docking Study ◽

Antimicrobial Activities ◽

Diffusion Method ◽

Molecular Docking Study ◽

Triazole Derivatives ◽

Antibacterial And Antifungal

Background: Thiosemicarbazone, 1,2,3-triazole and their derivatives received great pharmaceutical importance due to their prominent biological activities. In the present study, the molecular hybrid thiosemicarbazone-1,2,3-triazoles derivatives were synthesized and screened for their antimicrobial activities. Methods: A series of thiosemicarbazone clubbed with 1,2,3-triazole derivatives were synthesized via click chemistry approach in good yields. The structures of synthesized compounds were assigned by their spectral data. The in vitro antimicrobial activity was performed by the agar well diffusion method. A molecular docking study was performed to identify the possible mode of action of synthesized derivatives. Results: The compounds 5d, 5h, 5i and 5k have exhibited excellent antimicrobial activities against both antibacterial and antifungal pathogens. The active thiosemicarbazone-1,2,3-triazole derivatives have shown excellent binding affinity towards DNA gyrase. Conclusion: The molecular hybrid thiosemicarbazone-1,2,3-triazole derivatives were synthesized. The newly synthesized compounds were evaluated for their antimicrobial activities. Few of the thiosemicarbazone-1,2,3-triazoles derivatives have exhibited good antimicrobial activities. They have been shown excellent binding affinity towards DNA gyrase.

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Development of a blood sample detector for multi-tracer positron emission tomography using gamma spectroscopy

EJNMMI Physics ◽

10.1186/s40658-019-0263-x ◽

2019 ◽

Vol 6 (1) ◽

Cited By ~ 1

Author(s):

Carlos Velasco ◽

Adriana Mota-Cobián ◽

Jesús Mateo ◽

Samuel España

Keyword(s):

Positron Emission Tomography ◽

Blood Sample ◽

Pet Imaging ◽

Spectroscopic Analysis ◽

Gamma Spectroscopy ◽

Emission Tomography ◽

Blood Samples ◽

Positron Emission

Abstract Background Multi-tracer positron emission tomography (PET) imaging can be accomplished by applying multi-tracer compartment modeling. Recently, a method has been proposed in which the arterial input functions (AIFs) of the multi-tracer PET scan are explicitly derived. For that purpose, a gamma spectroscopic analysis is performed on blood samples manually withdrawn from the patient when at least one of the co-injected tracers is based on a non-pure positron emitter. Alternatively, these blood samples required for the spectroscopic analysis may be obtained and analyzed on site by an automated detection device, thus minimizing analysis time and radiation exposure of the operating personnel. In this work, a new automated blood sample detector based on silicon photomultipliers (SiPMs) for single- and multi-tracer PET imaging is presented, characterized, and tested in vitro and in vivo. Results The detector presented in this work stores and analyzes on-the-fly single and coincidence detected events. A sensitivity of 22.6 cps/(kBq/mL) and 1.7 cps/(kBq/mL) was obtained for single and coincidence events respectively. An energy resolution of 35% full-width-half-maximum (FWHM) at 511 keV and a minimum detectable activity of 0.30 ± 0.08 kBq/mL in single mode were obtained. The in vivo AIFs obtained with the detector show an excellent Pearson’s correlation (r = 0.996, p < 0.0001) with the ones obtained from well counter analysis of discrete blood samples. Moreover, in vitro experiments demonstrate the capability of the detector to apply the gamma spectroscopic analysis on a mixture of 68Ga and 18F and separate the individual signal emitted from each one. Conclusions Characterization and in vivo evaluation under realistic experimental conditions showed that the detector proposed in this work offers excellent sensibility and stability. The device also showed to successfully separate individual signals emitted from a mixture of radioisotopes. Therefore, the blood sample detector presented in this study allows fully automatic AIFs measurements during single- and multi-tracer PET studies.

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Effect of ethanol and cocaine on [11C]MPC-6827 uptake in SH-SY5Y cells

Molecular Biology Reports ◽

10.1007/s11033-021-06336-7 ◽

2021 ◽

Author(s):

Naresh Damuka ◽

Miranda Orr ◽

Paul W. Czoty ◽

Jeffrey L. Weiner ◽

Thomas J. Martin ◽

...

Keyword(s):

Mechanism Of Action ◽

Ex Vivo ◽

Neuroblastoma Cells ◽

Proper Function ◽

Brain Functions ◽

Biodistribution Studies ◽

Positron Emission ◽

Vitro Binding

AbstractMicrotubules (MTs) are structural units in the cytoskeleton. In brain cells they are responsible for axonal transport, information processing, and signaling mechanisms. Proper function of these processes is critical for healthy brain functions. Alcohol and substance use disorders (AUD/SUDs) affects the function and organization of MTs in the brain, making them a potential neuroimaging marker to study the resulting impairment of overall neurobehavioral and cognitive processes. Our lab reported the first brain-penetrant MT-tracking Positron Emission Tomography (PET) ligand [11C]MPC-6827 and demonstrated its in vivo utility in rodents and non-human primates. To further explore the in vivo imaging potential of [11C]MPC-6827, we need to investigate its mechanism of action. Here, we report preliminary in vitro binding results in SH-SY5Y neuroblastoma cells exposed to ethanol (EtOH) or cocaine in combination with multiple agents that alter MT stability. EtOH and cocaine treatments increased MT stability and decreased free tubulin monomers. Our initial cell-binding assay demonstrated that [11C]MPC-6827 may have high affinity to free/unbound tubulin units. Consistent with this mechanism of action, we observed lower [11C]MPC-6827 uptake in SH-SY5Y cells after EtOH and cocaine treatments (e.g., fewer free tubulin units). We are currently performing in vivo PET imaging and ex vivo biodistribution studies in rodent and nonhuman primate models of AUD and SUDs and Alzheimer's disease.

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Metabolic Glycoengineering in hMSC-TERT as a Model for Skeletal Precursors by Using Modified Azide/Alkyne Monosaccharides

International Journal of Molecular Sciences ◽

10.3390/ijms22062820 ◽

2021 ◽

Vol 22 (6) ◽

pp. 2820

Author(s):

Stephan Altmann ◽

Jürgen Mut ◽

Natalia Wolf ◽

Jutta Meißner-Weigl ◽

Maximilian Rudert ◽

...

Keyword(s):

Fluorescent Dyes ◽

Adipogenic Differentiation ◽

Culture Conditions ◽

Surface Proteins ◽

Differentiation Potential ◽

Or Gene ◽

Mannose Derivatives ◽

Metabolic Glycoengineering ◽

Scientific Questions

Metabolic glycoengineering enables a directed modification of cell surfaces by introducing target molecules to surface proteins displaying new features. Biochemical pathways involving glycans differ in dependence on the cell type; therefore, this technique should be tailored for the best results. We characterized metabolic glycoengineering in telomerase-immortalized human mesenchymal stromal cells (hMSC-TERT) as a model for primary hMSC, to investigate its applicability in TERT-modified cell lines. The metabolic incorporation of N-azidoacetylmannosamine (Ac4ManNAz) and N-alkyneacetylmannosamine (Ac4ManNAl) into the glycocalyx as a first step in the glycoengineering process revealed no adverse effects on cell viability or gene expression, and the in vitro multipotency (osteogenic and adipogenic differentiation potential) was maintained under these adapted culture conditions. In the second step, glycoengineered cells were modified with fluorescent dyes using Cu-mediated click chemistry. In these analyses, the two mannose derivatives showed superior incorporation efficiencies compared to glucose and galactose isomers. In time-dependent experiments, the incorporation of Ac4ManNAz was detectable for up to six days while Ac4ManNAl-derived metabolites were absent after two days. Taken together, these findings demonstrate the successful metabolic glycoengineering of immortalized hMSC resulting in transient cell surface modifications, and thus present a useful model to address different scientific questions regarding glycosylation processes in skeletal precursors.

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Hyaluronate/black phosphorus complexes as a copper chelating agent for Wilson disease treatment

Biomaterials Research ◽

10.1186/s40824-021-00221-x ◽

2021 ◽

Vol 25 (1) ◽

Author(s):

Seong-Jong Kim ◽

Hye Hyeon Han ◽

Sei Kwang Hahn

Keyword(s):

Targeted Delivery ◽

Wilson Disease ◽

Copper Ions ◽

Binding Capacity ◽

Genetic Disorder ◽

Chelating Agent ◽

Black Phosphorus ◽

The Body ◽

Copper Binding

Abstract Background Wilson disease (WD) is a genetic disorder of copper storage, resulting in pathological accumulation of copper in the body. Because symptoms are generally related to the liver, chelating agents capable of capturing excess copper ions after targeted delivery to the liver are highly required for the treatment of WD. Methods We developed hyaluronate-diaminohexane/black phosphorus (HA-DAH/BP) complexes for capturing copper ions accumulated in the liver for the treatment of WD. Results HA-DAH/BP complexes showed high hepatocyte-specific targeting efficiency, selective copper capturing capacity, excellent biocompatibility, and biodegradability. HA enhanced the stability of BP nanosheets and increased copper binding capacity. In vitro cellular uptake and competitive binding tests verified targeted delivery of HA-DAH/BP complexes to liver cells via HA receptor mediated endocytosis. The cell viability test confirmed the high biocompatibility of HA-DAH/BP complexes. Conclusion HA-DAH/BP complexes would be an efficient copper chelating agent to remove accumulated copper in the liver for the WD treatment.

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Development of 18F-Labeled Radiotracers for PET Imaging of the Adenosine A2A Receptor: Synthesis, Radiolabeling and Preliminary Biological Evaluation

International Journal of Molecular Sciences ◽

10.3390/ijms22052285 ◽

2021 ◽

Vol 22 (5) ◽

pp. 2285

Author(s):

Thu Hang Lai ◽

Susann Schröder ◽

Magali Toussaint ◽

Sladjana Dukić-Stefanović ◽

Mathias Kranz ◽

...

Keyword(s):

Specific Binding ◽

Brain Slices ◽

Total Activity ◽

Biological Evaluation ◽

Adenosine A2a Receptor ◽

Positron Emission ◽

A2a Receptor ◽

Adenosine A2a

The adenosine A2A receptor (A2AR) represents a potential therapeutic target for neurodegenerative diseases. Aiming at the development of a positron emission tomography (PET) radiotracer to monitor changes of receptor density and/or occupancy during the A2AR-tailored therapy, we designed a library of fluorinated analogs based on a recently published lead compound (PPY). Among those, the highly affine 4-fluorobenzyl derivate (PPY1; Ki(hA2AR) = 5.3 nM) and the 2-fluorobenzyl derivate (PPY2; Ki(hA2AR) = 2.1 nM) were chosen for 18F-labeling via an alcohol-enhanced copper-mediated procedure starting from the corresponding boronic acid pinacol ester precursors. Investigations of the metabolic stability of [18F]PPY1 and [18F]PPY2 in CD-1 mice by radio-HPLC analysis revealed parent fractions of more than 76% of total activity in the brain. Specific binding of [18F]PPY2 on mice brain slices was demonstrated by in vitro autoradiography. In vivo PET/magnetic resonance imaging (MRI) studies in CD-1 mice revealed a reasonable high initial brain uptake for both radiotracers, followed by a fast clearance.

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