99mTc-mercaptoacetyltriglycine (99mTc-MAG3), 99mTc-dd- and ll-ethylene-di-cysteine (99mTc-EC) and 99mTc-mercaptoacetamide-ethylene-cysteine (99mTc-MAEC) contain N3S or N2S2 ligands designed to accommodate the four ligating sites of the {99mTcO}3+ core; they are all excellent renal imaging agents but have renal clearances less than that of 131I-orthoiodohippurate (131I-OIH). To explore the potential of the newly accessible but less polar {99mTc(CO)3}+ core having three ligating sites, we decided to build on the success of 99mTc-EC with its N2S2 ligand and two dangling carboxylates and have chosen an N2S ligand that also has two dangling carboxyls, lanthionine (LANH2), to form 99mTc(CO)3(LAN), a new renal radiopharmaceutical.Methods
Biodistribution studies were performed on Sprague-Dawley rats by using 99mTc(CO)3(LAN) isomers, meso-LAN and dd,ll-LAN (an enantiomeric mixture), coinjected with 131I-OIH. Human studies were also performed by coinjecting each 99mTc product (~74 MBq [~2 mCi]) and 131I-OIH (~ 7.4 MBq [~ 0.2 mCi]) into 3 normal volunteers with dual-isotope imaging performed by using a camera system fitted with a high-energy collimator. Blood samples were obtained from 3 to 90 min after injection, and urine samples were obtained at 30, 90 and 180 min.
Results
Biodistribution studies in rats revealed a rapid blood clearance as well as rapid renal extraction for both preparations, with the dose in urine at 60 min averaging 88% that of 131I-OIH. In humans, both agents provided excellent renal images, with the plasma clearance averaging 228 mL/min for 99mTc(CO)3(meso-LAN) and 176 mL/min for 99mTc(CO)3(dd,ll-LAN), respectively. At 3 hours, both 99mTc(CO)3(meso-LAN) and 99mTc(CO)3(dd,ll-LAN), showed good renal excretion, averaging 85% and 77% that of 131I-OIH, respectively. Plasma protein binding was minimal (10% and 2%), and red cell uptake was similar (24% and 21%) for 99mTc(CO)3(meso-LAN) and 99mTc(CO)3(dd,ll-LAN), respectively.
Conclusion
Although the plasma clearance and the rate of renal excretion of the 99mTc(CO)3(LAN) complexes are still less than those of 131I-OIH, the results of this first application of a 99mTc tricarbonyl complex as a renal radiopharmaceutical in humans demonstrate that 99mTc(CO)3(LAN) complexes are excellent renal imaging agents and support continued renal radiopharmaceutical development based on the 99mTc tricarbonyl core.
Purpose: To study whether miR-21, an oncogene associated with lung tumorigenesis, affects immune response. Material and methods: Cancer immune-related 786 mRNA expression was compared in lung tissue from wild-type and miR-21 knock-in mice using NanoString technology. The significantly changed genes were verified using real-time PCR. E-Selectin (Sele) was subsequently identified for further examination using immunohistochemistry (IHC) and Western blot in the same lung tissue. The mouse Sele 3’untranslated region (3’-UTR) was searched to identify a miR-21 matching sequence. The Sele level in miR-21 mimic transfected mouse lung bronchial epithelial (LBE) cells was examined. Results: We unexpectedly found that the Sele mRNA level significantly increased but the protein level significantly decreased in the lung tissue of miR-21 knock-in mice compared to the mRNA/protein levels in the lung tissue of wild-type mice. The mouse Sele 3'-UTR contains the key sequence that can be targeted by miR-21. The Sele levels decreased in mouse LBE cells after miR-21 mimic transfection. Conclusion: Sele is a potential miR-21 target. The opposing Sele levels at mRNA and protein suggest a feedback-regulation from protein to mRNA. The feedback-regulation in miR-21-suppressed gene expression indicates that we should carefully evaluate any data from mRNA array since they may not reflect real protein expression status.
by
Stéphanie Morchoisne-Bolhy;
Marie-Claude Geoffroy;
Imène B. Bouhlel;
Annabelle Alves;
Nicolas Auduge;
Xavier Baudin;
Kevin Van Bortle;
Maureen Powers;
Valérie Doye
Nup98 is a glycine-leucine-phenylalanine-glycine (GLFG) repeat-containing nucleoporin that, in addition to nuclear transport, contributes to multiple aspects of gene regulation. Previous studies revealed its dynamic localization within intranuclear structures known as GLFG bodies. Here we show that the mammalian Nup107-160 complex (Y-complex), a major scaffold module of the nuclear pore, together with its partner Elys, colocalizes with Nup98 in GLFG bodies. The frequency and size of GLFG bodies vary among HeLa sublines, and we find that an increased level of Nup98 is associated with the presence of bodies. Recruitment of the Y-complex and Elys into GLFG bodies requires the C-terminal domain of Nup98. During cell division, Y-Nup-containing GLFG bodies are disassembled in mitotic prophase, significantly ahead of nuclear pore disassembly. FRAP studies revealed that, unlike at nuclear pores, the Y-complex shuttles into and out of GLFG bodies. Finally, we show that within the nucleoplasm, a fraction of Nup107, a key component of the Y-complex, displays reduced mobility, suggesting interaction with other nuclear components. Together our data uncover a previously neglected intranuclear pool of the Y-complex that may underscore a yet-uncharacterized function of these nucleoporins inside the nucleus, even in cells that contain no detectable GLFG bodies.
Conventional anatomical imaging with CT and MRI has limitations in the evaluation of prostate cancer. PET is a powerful imaging technique, which can be directed toward molecular targets as diverse as glucose metabolism, density of prostate-specific membrane antigen receptors, and skeletal osteoblastic activity. Although 2-deoxy-2- 18 F-FDG-PET is the mainstay of molecular imaging, FDG has limitations in typically indolent prostate cancer. Yet, there are many useful and emerging PET tracers beyond FDG, which provide added value. These include radiotracers interrogating prostate cancer via molecular mechanisms related to the biology of choline, acetate, amino acids, bombesin, and dihydrotestosterone, among others. Choline is used for cell membrane synthesis and its metabolism is upregulated in prostate cancer. 11 C-choline and 18 F-choline are in wide clinical use outside the United States, and they have proven most beneficial for detection of recurrent prostate cancer. 11 C-acetate is an indirect biomarker of fatty acid synthesis, which is also upregulated in prostate cancer. Imaging of prostate cancer with 11 C-acetate is overall similar to the choline radiotracers yet is not as widely used. Upregulation of amino acid transport in prostate cancer provides the biologic basis for amino acid–based radiotracers. Most recent progress has been made with the nonnatural alicyclic amino acid analogue radiotracer anti-1-amino-3- 18 F-fluorocyclobutane-1-carboxylic acid (FACBC or fluciclovine) also proven most useful for the detection of recurrent prostate cancer. Other emerging PET radiotracers for prostate cancer include the bombesin group directed to the gastrin-releasing peptide receptor, 16β- 18 F-fluoro-5α-dihydrotestosterone (FDHT) that binds to the androgen receptor, and those targeting the vasoactive intestinal polypeptide receptor 1 (VPAC-1) and urokinase plasminogen activator receptor (uPAR), which are also overexpressed in prostate cancer.
Nuclear pore complexes (NPCs) facilitate selective transport of macromolecules across the nuclear envelope in interphase eukaryotic cells. NPCs are composed of roughly 30 different proteins (nucleoporins) of which about one third are characterized by the presence of phenylalanine-glycine (FG) repeat domains that allow the association of soluble nuclear transport receptors with the NPC. Two types of FG (FG/FxFG and FG/GLFG) domains are found in nucleoporins and Nup98 is the sole vertebrate nucleoporin harboring the GLFG-type repeats. By immuno-electron microscopy using isolated nuclei from Xenopus oocytes we show here the localization of distinct domains of Nup98. We examined the localization of the C- and N-terminal domain of Nup98 by immunogold-labeling using domain-specific antibodies against Nup98 and by expressing epitope tagged versions of Nup98. Our studies revealed that anchorage of Nup98 to NPCs through its C-terminal autoproteolytic domain occurs in the center of the NPC, whereas its N-terminal GLFG domain is more flexible and is detected at multiple locations within the NPC. Additionally, we have confirmed the central localization of Nup98 within the NPC using super resolution structured illumination fluorescence microscopy (SIM) to position Nup98 domains relative to markers of cytoplasmic filaments and the nuclear basket. Our data support the notion that Nup98 is a major determinant of the permeability barrier of NPCs.
The novel PET radioligand 11C-N,N-dimethyl-2-(2′-amino-4′-hydroxymethylphenylthio)benzylamine (11C-HOMADAM) binds with high affinity and selectively to the serotonin transporter (SERT). The purpose of this study was to develop a reliable kinetic model to describe the uptake of 11C-HOMADAM in the healthy human brain.Methods
Eight volunteers participated in the study; 5 of them were fitted with arterial catheters for blood sampling and all were scanned on a high-resolution research tomograph after the injection of 11C-HOMADAM. Regional distribution volumes and binding potentials were calculated with 2- and 4-parameter arterial-input compartment models, a 3-parameter reference tissue compartment model, and the Logan graphic approach.
Results
The 2-parameter arterial-input compartment model was statistically superior to the 4-parameter model and described all brain regions. Calculated binding potentials agreed well between the arterial-input model and the reference tissue model when the cerebellum was used as the reference tissue. The Logan graphic approach was not able to estimate the higher concentration of SERT in the dorsal raphe than in the midbrain.
Conclusion
11C-HOMADAM is a highly promising radioligand with high ratios of specific binding to nonspecific binding in known SERT-rich structures, such as the raphe nuclei. The 3-parameter reference tissue model approach permits a simplified quantitatively accurate method for estimating SERT binding potentials.