| 1. |
- Cheng, Qing, et al.
(författare)
-
Preclinical PET imaging of EGFR levels : pairing a targeting with a non-targeting Sel-tagged Affibody-based tracer to estimate the specific uptake
- 2016
-
Ingår i: EJNMMI Research. - : Springer. - 2191-219X. ; 6
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Though overexpression of epidermal growth factor receptor (EGFR) in several forms of cancer is considered to be an important prognostic biomarker related to poor prognosis, clear correlations between biomarker assays and patient management have been difficult to establish. Here, we utilize a targeting directly followed by a non-targeting tracer-based positron emission tomography (PET) method to examine some of the aspects of determining specific EGFR binding in tumors. Methods: The EGFR-binding Affibody molecule Z(EGFR:2377) and its size-matched non-binding control Z(Taq:3638) were recombinantly fused with a C-terminal selenocysteine-containing Sel-tag (Z(EGFR:2377)-ST and Z(Taq:3638)-ST). The proteins were site-specifically labeled with DyLight488 for flow cytometry and ex vivo tissue analyses or with C-11 for in vivo PET studies. Kinetic scans with the C-11-labeled proteins were performed in healthy mice and in mice bearing xenografts from human FaDu (squamous cell carcinoma) and A431 (epidermoid carcinoma) cell lines. Changes in tracer uptake in A431 xenografts over time were also monitored, followed by ex vivo proximity ligation assays (PLA) of EGFR expressions. Results: Flow cytometry and ex vivo tissue analyses confirmed EGFR targeting by ZE(GFR:2377)-ST-DyLight488. [Methyl-C-11]-labeled Z(EGFR:2377)-ST-CH3 and Z(Taq:3638)-ST-CH3 showed similar distributions in vivo, except for notably higher concentrations of the former in particularly the liver and the blood. [Methyl-C-11]-Z(EGFR:2377)-ST-CH3 successfully visualized FaDu and A431 xenografts with moderate and high EGFR expression levels, respectively. However, in FaDu tumors, the non-specific uptake was large and sometimes equally large, illustrating the importance of proper controls. In the A431 group observed longitudinally, non-specific uptake remained at same level over the observation period. Specific uptake increased with tumor size, but changes varied widely over time in individual tumors. Total (membranous and cytoplasmic) EGFR in excised sections increased with tumor growth. There was no positive correlation between total EGFR and specific tracer uptake, which, since Z(EGFR:2377) binds extracellularly and is slowly internalized, indicates a discordance between available membranous and total EGFR expression levels. Conclusions: Same-day in vivo dual tracer imaging enabled by the Sel-tag technology and C-11-labeling provides a method to non-invasively monitor membrane-localized EGFR as well as factors affecting non-specific uptake of the PET ligand.
|
|
| 2. |
- Hagberg, Carolina E, et al.
(författare)
-
Vascular endothelial growth factor B controls endothelial fatty acid uptake.
- 2010
-
Ingår i: Nature. - : Springer Science and Business Media LLC. - 1476-4687 .- 0028-0836. ; 464:7290, s. 917-21
-
Tidskriftsartikel (refereegranskat)abstract
- The vascular endothelial growth factors (VEGFs) are major angiogenic regulators and are involved in several aspects of endothelial cell physiology. However, the detailed role of VEGF-B in blood vessel function has remained unclear. Here we show that VEGF-B has an unexpected role in endothelial targeting of lipids to peripheral tissues. Dietary lipids present in circulation have to be transported through the vascular endothelium to be metabolized by tissue cells, a mechanism that is poorly understood. Bioinformatic analysis showed that Vegfb was tightly co-expressed with nuclear-encoded mitochondrial genes across a large variety of physiological conditions in mice, pointing to a role for VEGF-B in metabolism. VEGF-B specifically controlled endothelial uptake of fatty acids via transcriptional regulation of vascular fatty acid transport proteins. As a consequence, Vegfb(-/-) mice showed less uptake and accumulation of lipids in muscle, heart and brown adipose tissue, and instead shunted lipids to white adipose tissue. This regulation was mediated by VEGF receptor 1 and neuropilin 1 expressed by the endothelium. The co-expression of VEGF-B and mitochondrial proteins introduces a novel regulatory mechanism, whereby endothelial lipid uptake and mitochondrial lipid use are tightly coordinated. The involvement of VEGF-B in lipid uptake may open up the possibility for novel strategies to modulate pathological lipid accumulation in diabetes, obesity and cardiovascular diseases.
|
|
| 3. |
- Manouilenko, Irina, et al.
(författare)
-
Autistic traits, ADHD symptoms, neurological soft signs and regional cerebral blood flow in adults with autism spectrum disorders
- 2013
-
Ingår i: Research in Autism Spectrum Disorders. - Oxon, United Kingdom : Elsevier. - 1750-9467 .- 1878-0237. ; 7, s. 566-578
-
Tidskriftsartikel (refereegranskat)abstract
- The resting regional cerebral blood flow (rCBF) patterns related to co-occurring symptoms such as inattention, hyperactivity, neurological soft signs and motor problems have not yet been disclosed in autism spectrum disorders (ASD). In this study thirteen adults with ASD and ten matched neurotypical controls underwent PET. The scores of rating scales for autistic traits, attention deficit hyperactivity disorder (ADHD) and neurological soft signs were included in a factorial analysis and correlated with rCBF. Factors corresponding to “autistic/ADHD traits”, “sensory-motor integration” and “intelligence/motor sequencing” were identified. In the ASD group, positive correlations with CBF were found for “autistic/ADHD traits” in caudate bilaterally and the inferior parietal lobule, for “sensory-motor integration” in parieto-occipital cortex and for “intelligence/motor sequencing” in the right temporal cortex. Notably, CBF in the left thalamus correlated negatively with all three factors. Autistic traits and ADHD symptoms were associated with shared neural substrates. The correlation between “autistic/ADHD traits” and rCBF in the caudate is possibly associated with the executive impairments and ritualistic/stereotyped behaviors apparent in ASD. Furthermore, sensory-motor deficits were correlated with rCBF in the occipital visual cortex, involved in atypical visual perception in ASD. Various behavioral and neurological symptoms are suggested to converge into the ASD phenotype.
|
|
| 4. |
- Olsen, Jessica M., et al.
(författare)
-
β3-Adrenergically induced glucose uptake in brown adipose tissue is independent of UCP1 presence or activity : Mediation through the mTOR pathway
- 2017
-
Ingår i: Molecular Metabolism. - : Elsevier BV. - 2212-8778. ; 6:6, s. 611-619
-
Tidskriftsartikel (refereegranskat)abstract
- ObjectiveToday, the presence and activity of brown adipose tissue (BAT) in adult humans is generally equated with the induced accumulation of [2-18F]2-fluoro-2-deoxy-d-glucose([18F]FDG) in adipose tissues, as investigated by positron emission tomography (PET) scanning. In reality, PET-FDG is currently the only method available for in vivoquantification of BAT activity in adult humans. The underlying assumption is that the glucose uptake reflects the thermogenic activity of the tissue.MethodsTo examine this basic assumption, we here followed [18F]FDG uptake by PET and by tissue [3H]-2-deoxy-d-glucose uptake in wildtype and UCP1(−/−) mice, i.e. in mice that do or do not possess the unique thermogenic and calorie-consuming ability of BAT.ResultsUnexpectedly, we found that β3-adrenergically induced (by CL-316,243) glucose uptake was UCP1-independent. Thus, whereas PET-FDG scans adequately reflect glucose uptake, this acute glucose uptake is not secondary to thermogenesis but is governed by an independent cellular signalling, here demonstrated to be mediated via the previously described KU-0063794-sensitive mTOR pathway.ConclusionsThus, PET-FDG scans do not exclusively reveal active BAT deposits but rather any tissue possessing an adrenergically-mediated glucose uptake pathway. In contrast, we found that the marked glucose uptake-ameliorating effect of prolonged β3-adrenergictreatment was UCP1 dependent. Thus, therapeutically, UCP1 activity is required for any anti-diabetic effect of BAT activation.
|
|
| 5. |
- Orlova, Anna, et al.
(författare)
-
On the Selection of a Tracer for PET Imaging of HER2-Expressing Tumors : Direct Comparison of a (124)I-Labeled Affibody Molecule and Trastuzumab in a Murine Xenograft Model
- 2009
-
Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 1535-5667 .- 2159-662X .- 0340-6997 .- 1432-105X. ; 50:3, s. 417-425
-
Tidskriftsartikel (refereegranskat)abstract
- Human epidermal growth factor receptor type 2 (HER2) is a tyrosine kinase, which is often overexpressed in many carcinomas. Imaging HER2 expression in malignant tumors can provide important prognostic and predictive diagnostic information. The use of anti-HER2 tracers labeled with positron-emitting radionuclides may increase the sensitivity of HER2 imaging. The goal of this study was to compare directly 2 approaches for developing anti-HER2 PET tracers: a (124)I-labeled monoclonal antibody and a small (7-kDa) scaffold protein, the Affibody molecule, Methods: The anti-HER2 Affibody Z(HER2:342) and humanized monoclonal antibody trastuzumab were labeled with (124/125)I using p-iodobenzoate (PIB) as a linker. Cellular processing of both tracers by HER2-expressing cells was investigated. The biodistributions of (124)I-PIB-Z(HER2:342) and (125)I-PIB-trastuzumab were compared in BALB/C nu/nu mice bearing HER2-expressing NCI-N87 xenografts using paired labels. Small-animal PET of (124)I-PIB-Z(HER2:342) and (124)I-PIB-trastuzumab in tumor-bearing mice was performed at 6, 24, and 72 h after injection. Results: Both radioiodinated Z(HER2:342) and trastuzumab bound specifically to HER2-expressing cells in vitro and specifically targeted HER2-expressing xenografts in vivo. Radioiodinated trastuzumab was more rapidly internalized and degraded, which resulted in better retention of radioactivity delivered by Z(HER2:342). Total uptake of trastuzumab in tumors was higher than that of (124)I-PIB-Z(HER2:342). However, tumor-to-organ ratios were appreciably higher for (124)I-PIB-Z(HER2:342) due to the more rapid clearance of radioactivity from blood and normal organs. The ex vivo results were confirmed by small-animal PET. Conclusion: The use of the small scaffold targeting Affibody provides better contrast in HER2 imaging than does the monoclonal antibody.
|
|
| 6. |
- Pagani, Marco, et al.
(författare)
-
Brief Report : alterations in cerebral blood flow as assessed by PET/CT in adults with autism spectrum disorder with normal IQ
- 2012
-
Ingår i: Journal of autism and developmental disorders. - New York, USA : Springer. - 0162-3257 .- 1573-3432. ; 42:2, s. 313-318
-
Tidskriftsartikel (refereegranskat)abstract
- Specific biological markers for autism spectrum disorder (ASD) have not yet been established. Functional studies have shown abnormalities in the anatomo-functional connectivity of the limbic-striatal "social" brain. This study aimed to investigate regional cerebral blood flow (rCBF) at rest. Thirteen patients with ASD of normal intelligence and ten IQ-, sex- and age-matched healthy controls (HC) underwent PET/CT using [1-(11)C]butanol, a perfusion tracer. As compared to HC, ASD showed significant CBF increases in the right parahippocampal, posterior cingulate, primary visual and temporal cortex, putamen, caudatus, substantia nigra and cerebellum. No statistically significant correlation between CBF and IQ was found. The limbic, posterior associative and cerebellar cortices showed increased blood flow in ASD, confirming previous findings about the neurobiology of ASD.
|
|
| 7. |
|
|
| 8. |
- Samuelsson, Linda, 1973-
(författare)
-
Methods for the Synthesis of PET Tracers and NMR Studies of Ribonuclease A
- 2005
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis contains two parts.In the first part, general and versatile palladium-mediated 11C-C bond forming reactions for use in the production of radiotracers for Positron Emission Tomography (PET) were explored. Two complimentarty approaches were investigated: the coupling of [11C]methyl iodide with a vinyl stannane and the reaction of a [11C]methylated stannane with various organohalides. The former approach resulted in an improved, fully automated method for the synthesis of the potential cell proliferation tracer 1-(2’-deoxy-2’-fluoro-β-D-arabinofuranosyl)-[methyl-11C]- thymine. The tracer was obtained in an isolated decay-corrected radiochemical yield of 28% at 25 min after end of radionuclide production. In the latter approach, a [11C]methylated tricyclic stannane (5-[11C]methyl-1-aza- 5-stannabicyclo[3.3.3]undecane) was synthesised in 47% decay-corrected radiochemical yield, starting from [11C]methyl iodide. This stannane was successfully employed in palladium-mediated coupling reactions with aryl, heteroaryl and vinyl halides.In the second part, effects of the osmolytes glycine betaine, trimethylamine N-oxide (TMAO) and urea on Ribonuclease A (RNase A) were investigated using Nuclear Magnetic Resonance (NMR) spectroscopy. Changes in the enzymatic activity in the presence of these osmolytes at concentrations of ≤1 M were observed by monitoring the RNase A-catalysed degradation of polyuridylic acid using 31P NMR spectroscopy. The decrease in activity caused by urea was counteracted by both glycine betaine and TMAO at a molar ratio of 1:1.4 and 1:1, respectively.To investigate if the observed activity changes were accompanied by any detectable alteration in the gross conformation of RNase A, diffusion coefficients for the enzyme in the various osmolyte solutions were measured using pulsed-field gradient NMR. A pulse sequence suitable for diffusion measurements in highly concentrated aqueous osmolyte solutions was developed and assessed. The diffusion of RNase A was measured relative to a new internal standard, 2,2,5,5,-tetramethyl-1,4-dioxane. No clear, detectable change in the relative diffusion of RNase A was observed in these media.
|
|
| 9. |
- Stafford, William C., et al.
(författare)
-
Irreversible inhibition of cytosolic thioredoxin reductase 1 as a mechanistic basis for anticancer therapy
- 2018
-
Ingår i: Science Translational Medicine. - : AMER ASSOC ADVANCEMENT SCIENCE. - 1946-6234 .- 1946-6242. ; 10:428
-
Tidskriftsartikel (refereegranskat)abstract
- Cancer cells adapt to their inherently increased oxidative stress through activation of the glutathione (GSH) and thioredoxin (TXN) systems. Inhibition of both of these systems effectively kills cancer cells, but such broad inhibition of antioxidant activity also kills normal cells, which is highly unwanted in a clinical setting. We therefore evaluated targeting of the TXN pathway alone and, more specifically, selective inhibition of the cytosolic selenocysteine-containing enzyme TXN reductase 1 (TXNRD1). TXNRD1 inhibitors were discovered in a large screening effort and displayed increased specificity compared to pan-TXNRD inhibitors, such as auranofin, that also inhibit the mitochondrial enzyme TXNRD2 and additional targets. For our lead compounds, TXNRD1 inhibition correlated with cancer cell cytotoxicity, and inhibitor-triggered conversion of TXNRD1 from an antioxidant to a pro-oxidant enzyme correlated with corresponding increases in cellular production of H2O2. In mice, the most specific TXNRD1 inhibitor, here described as TXNRD1 inhibitor 1 (TRi-1), impaired growth and viability of human tumor xenografts and syngeneic mouse tumors while having little mitochondrial toxicity and being better tolerated than auranofin. These results display the therapeutic anticancer potential of irreversibly targeting cytosolic TXNRD1 using small molecules and present potent and selective TXNRD1 inhibitors. Given the pronounced up-regulation of TXNRD1 in several metastatic malignancies, it seems worthwhile to further explore the potential benefit of specific irreversible TXNRD1 inhibitors for anticancer therapy.
|
|
| 10. |
- Tolmachev, Vladimir, et al.
(författare)
-
Radiolabelled proteins for positron emission tomography : pros and cons of labelling methods
- 2010
-
Ingår i: Biochimica et Biophysica Acta. - : Elsevier BV. - 0006-3002 .- 1878-2434 .- 0304-4165. ; 1800:5, s. 487-510
-
Forskningsöversikt (refereegranskat)abstract
- BACKGROUND: Dynamic biomedical research is currently yielding a wealth of information about disease-associated molecular alterations on cell surfaces and in the extracellular space. The ability to visualize and quantify these alterations in vivo could provide important diagnostic information and be used to guide individually-optimized therapy. Biotechnology can provide proteinaceous molecular probes with highly specific target recognitions. Suitably labelled, these may be used as tracers for radionuclide-based imaging of molecular disease signatures. If the labels are positron-emitting radionuclides, the superior resolution, sensitivity and quantification capability of positron emission tomography (PET) can be exploited. SCOPE OF REVIEW: This article discusses different approaches to labelling proteins with positron-emitting nuclides with suggestions made depending on the biological features of the tracers. MAJOR CONCLUSIONS: Factors such as matching biological and physical half-lives, availability of the nuclide, labelling yields, and influences of labelling on targeting properties (affinity, charge and lipophilicity, cellular processing and retention of catabolites) should be considered when selecting a labelling strategy for each proteinaceous tracer. GENERAL SIGNIFICANCE: The labelling strategy used can make all the difference between success and failure in a tracer application. This review emphasises chemical, biological and pharmacological considerations in labelling proteins with positron-emitting radionuclides.
|
|
