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Tumor receptor-targeted diagnostic imaging is an area of research that identifies a biomarker that is overexpressed on the surface of cancer cells and binds its ligand to carriers, allowing imaging of the tumor process. The success of this approach depends on the selectivity of the receptor for certain malignant cells, as well as on its ability to specifically bind to the target ligand. This review examines the diagnostic role of the bombesin family of receptors, which focus on gastrin-releasing peptide receptors (GRPR), which are overexpressed in various cancers. For tumors expressing GRPR, the diagnostic informativeness of the detection of both primary tumor foci and metastases is high. The well-known concept of tumor heterogeneity has led to the development of bivalent prostate cancer - target peptides with the ability to target two receptors. Radiolabeled bombesin analogues are promising theranostic agents for tumors that express GRPR, which opens the possibility of early detection of primary tumors and metastatic lesions with high sensitivity and specificity. At the same time, further forward-looking clinical trials are needed to improve understanding of the relationship between GRPR expression and the biological behavior of different cancer cells. Key words: gastrin-releasing peptide receptors, bombesin, theranostic, oncology

Purpose of review The current review aims to update the important findings about molecular and cellular biology of mammalian bombesin-like peptides (BLPs) and their receptors. Recent findings Recent identification of synaptic communication between gastrin-releasing peptide (GRP) neurons and GRP receptor (GRPR) neurons in spinal itch relay provides us novel insights into physiology of itch sensation. Neuromedin B (NMB) neurons were found to form connections with subcortical areas associated with arousal, hippocampal theta oscillation, and premotor processing and project to multiple downstream stations to regulate locomotion and hippocampal theta power. In addition to researches regarding the roles of BLPs and their receptors in central nervous system, recent findings reveal that NMB receptor is expressed on helminth-induced type 2 innate lymphoid cells and is regulated by basophils, suggesting an important function of NMB in helminth-induced immune responses. Bombesin transactivates epidermal growth factor receptor (EGFR), human epidermal growth factor receptor 2 (HER2), and HER3 receptors on human nonsmall-cell lung cancer (NSCLC) cells and elicits downstream signaling cascades and induces formation of both human epidermal growthfactor receptor 3 (HER3)/EGFR and HER3/HER2 heterodimers. Several high-affinity ligands for bombesin receptors were characterized, providing useful tools in investigation of biological roles of those peptides and their receptors. Summary The most exciting findings of BLPs and their receptors in the past year come from studies in central nervous system. In addition, more researches are still underway to probe the molecular mechanisms of those peptides in peripheral tissues and characterize novel synthetic ligands with high affinity for mammalian bombesin receptors.

Hepatic bile formation under bombesin action (1 µg/100 g body weight, intraportally) was examined in acute experiments on 30 male rats of three age categories: juvenile (body weight 130-175 g), adult (200-250 g) and elder (more than 300 g). Changes in the bile flow rate were recorded and the amount of various bile acids (BA) was detected using thin layer chromatography/densitometry. Bombesin caused the increase of the bile flow rate in juvenile and adult rats without any effect on it in old animals. The concentration of free bile acids increased in juvenile and adult rats and decreased in old animals. This peptide stimulated secretion of taurocholic and glicocholic acids in adult and aged rats but had no effect on the secretion of tauroconjugated dihydroxycholates. Secretion of dihydroxy bile salts conjugated with glycine was more potently enhanced by bombesin in adult rats but in the elder group this parameter dropped below the control. Bombesin had a lower effect on the BA secretion in aged rats but its influence on the juvenile animals was bidirectional. In this group the peptide stimulates free bile salts formation and, without affecting de novo synthesis, inhibits BA conjugation with amino acids in aged group. Bombesin activated classic pathway of BA biosynthesis in juvenile rats and suppressed it in aged animals. The data obtained demonstrate that different effect of bombesin on bile acids content in rats of different age could change biliary lipid-solubilizing capacity under age related damage of the gut with impairment of normal bombesin release.

Objectives Pulmonary neuroendocrine cells (NEC) increase with the age due to pulmonary maturity. The aim of this study was to determine whether open lung biopsies from patients with interstitial lung diseases have increased pulmonary NEC compared with NEHI. Our second aim was to assess pulmonary NECs in the lung autopsy of children without lung disease who died from different causes. Methods Lung tissue of 5 infants with neuroendocrine cell hyperplasia of infancy (NEHI); 21 patients with pediatric interstitial lung disease (chILD); 17 lung autopsies of infants at varying age without lung disease were included. The percentage of the airways containing neuroendocrine cells, the average percentage of NECs per airway and the number of neuroendocrine bodies (NEBs) in each case were analyzed. Results The mean percentage of the airways containing neuroendocrine cells were 95% in NEHI group, 30% in chILD group, 89% under intrauterine 37 weeks, 70% between intrauterine 37-40 weeks, 52% at postnatal 4 days-6 months of autopsy ages. In NEHI group, diffuse NE cell distribution and large NEBs were noticed in the lung biopsy. In chILD group, neuroendocrine cells were dispersed, did not form clusters and NE cells showed solitary distribution. In lung autopsy group, linear NE cells were detected at younger aged fetuses and solitary distribution of NE cells was detected with the older increasing age. Conclusions Our findings confirm that NECs are seen in many other childhood ILDs; NE cell hyperplasia may be a marker of decreased pulmonary development and NE cells decrease with the increasing age of the fetus during intrauterine life. This article is protected by copyright. All rights reserved.

There are various diagnostic and therapeutic agents for prostate cancer using bombesin (BBN) derivatives, but astatine-211 (211At)-labeled BBN derivatives have yet to be studied. This study presented a preliminary evaluation of 211At-labeled BBN derivative. Several nonradioactive iodine-introduced BBN derivatives (IB-BBNs) with different linkers were synthesized and their binding affinities measured. Because IB-3 exhibited a comparable affinity to native BBN, [211At]AB-3 was synthesized and the radiochemical yields of [211At]AB-3 was 28.2 ± 2.4%, with a radiochemical purity of >90%. The stability studies and cell internalization/externalization experiments were performed. [211At]AB-3 was taken up by cells and internalized; however, radioactivity effluxed from cells over time. In addition, the biodistribution of [211At]AB-3, with and without excess amounts of BBN, were evaluated in PC-3 tumor-bearing mice. Despite poor stability in murine plasma, [211At]AB-3 accumulated in tumor tissue (4.05 ± 0.73%ID/g) in PC-3 tumor-bearing mice, which was inhibited by excess native BBN (2.56 ± 0.24%ID/g). Accumulated radioactivity in various organs is probably due to free 211At. Peptide degradation in murine plasma and radioactivity efflux from cells are areas of improvement. The development of 211At-labeled BBN derivatives requires modifying the BBN sequence and preventing deastatination.

Developments in the design of lanthanide oxide nanoparticles (NPs) have unleashed a wide variety of biomedical applications. Several types of hepatic cancer cells overexpress two proteins: the gastrin-releasing peptide receptor (GRPr), which specifically recognizes the bombesin (BN) peptide, and the prostate-specific membrane antigen (PSMA), which specifically binds to several peptides that inhibit its activity (iPSMA). This research synthesized and physicochemically characterized Sm2O3 nanoparticles functionalized with the iPSMA-BN heterodimeric peptide and studied the effects on their structural, biochemical and preclinical properties after activation by neutron irradiation for possible use in molecular dual-targeted radiotherapy of hepatocellular carcinoma. The Sm2O3 NPs were synthesized by the precipitation-calcination method and functionalized with iPSMA-BN peptide using the DOTA macrocycle as a linking agent. Analysis of physicochemical characterization via TEM, EDS, XRD, UV-Vis, FT-IR, DSL, and zeta potential results showed the formation of Sm2O3-iPSMA-BN NPs (94.23 ± 5.98 nm), and their physicochemical properties were not affected after neutron activation. The nanosystem showed a high affinity with respect to PSMA and GRPr in HepG2 cells ( Kd = 6.6 ± 1.6 nM) and GRPr in PC3 cells ( Kd = 10.6 ± 1.9 nM). 153Sm2O3-iPSMA-BN NPs exhibited radioluminescent properties, making possible in vivo optical imaging of their biodistribution in mice. The results obtained from this research support further preclinical studies designed to evaluate the dosimetry and therapeutic efficacy of 153Sm2O3-iPSMA-BN nanoparticles for in vivo imaging and molecular dual-targeted radiotherapy of liver tumors overexpressing PSMA and/or GRPr proteins.

Excessive activation of the sympatho-adrenomedullary system plays a pathogenic role in triggering and sustaining essential hypertension. We previously reported that, in normotensive rats, intracerebroventricularly (i.c.v.) administered neuropeptides, corticotropin-releasing factor and bombesin induced activation of the sympatho-adrenomedullary system, and that brain cannabinoid CB1 receptors negatively regulated this activation. In this study, we investigated the effects of brain CB1 receptor stimulation on blood pressure and the sympatho-adrenomedullary outflow in spontaneously hypertensive rats (SHRs), commonly used animal models of essential hypertension, and in Wistar-Kyoto (WKY) rats, normotensive controls of SHRs. In 18-week-old SHRs and WKY rats under urethane anaesthesia (1.0 g/kg, i.p.), SHRs exhibited significantly higher systolic, mean and diastolic blood pressures and plasma noradrenaline and adrenaline, and a lower heart rate than WKY rats. Single administration of arachidonyl 2'-chloroethylamide (ACEA, CB1 agonist, 1.4 µmol/animal, i.c.v.) significantly but partially reduced mean and diastolic blood pressures and the plasma level of noradrenaline in SHRs compared to vehicle (N,N-dimethylformamide)-treated SHRs. These ACEA-induced reductions were abolished by central pretreatment with rimonabant (CB1 antagonist, 300 nmol/animal, i.c.v.), which alone showed no significant effect on blood pressures or plasma noradrenaline and adrenaline levels of SHRs. On the other hand, ACEA had no significant effect on blood pressure or plasma noradrenaline and adrenaline levels in WKY rats. These results suggest that stimulation of brain CB1 receptors can ameliorate hypertension accompanied by enhanced sympathetic outflow without affecting blood pressure under normotensive conditions.

The gastrin-releasing peptide receptor (GRPR) is overexpressed in prostate cancer and other solid malignancies. Following up on our work on [68 Ga]Ga-ProBOMB1 that had better imaging characteristics than [68 Ga]Ga-NeoBOMB1, we investigated the effects of substituting 68 Ga for 177 Lu to determine if the resulting radiopharmaceuticals could be used with a therapeutic aim. We radiolabeled the bombesin antagonist ProBOMB1 (DOTA-pABzA-DIG-D-Phe-Gln-Trp-Ala-Val-Gly-His-Leu-ψ-Pro-NH2 ) with lutetium-177 and compared it with [177 Lu]Lu-NeoBOMB1 (obtained in 54.2 ± 16.5% isolated radiochemical yield with >96% radiochemical purity and 440.8 ± 165.1 GBq/μmol molar activity) for GRPR targeting. Lu-NeoBOMB1 had better binding affinity for GRPR than Lu-ProBOMB1 (Ki values: 2.26 ± 0.24 and 30.2 ± 3.23nM). [177 Lu]Lu-ProBOMB1 was obtained in 53.7 ± 5.4% decay-corrected radiochemical yield with 444.2 ± 193.2 GBq/μmol molar activity and >95% radiochemical purity. In PC-3 prostate cancer xenograft mice, tumor uptake of [177 Lu]Lu-ProBOMB1 was 3.38 ± 1.00, 1.32 ± 0.24, and 0.31 ± 0.04%ID/g at 1, 4, and 24 hours pi. However, the uptake in tumor was lower than [177 Lu]Lu-NeoBOMB1 at all time points. [177 Lu]Lu-ProBOMB1 was inferior to [177 Lu]Lu-NeoBOMB1, which had better therapeutic index for the organs receiving the highest doses.

This Bombesin (BBN), a tetradecapeptide analog of human gastrin-releasing peptide (GRP) with a high binding affinity for GRP receptors (GRPR), is over- expressed in early stages of androgen-dependent prostate carcinomas, but not in advanced stages. Therefore, there is a need to develop effective tracers for the accurate and specific detection of this disease. The objective of this study was to evaluate Lys1, Lys3-DOTA-BBN (1,14) analog with the radiolabeled positron emitter [68Ga]-Ga-BBN for receptor imaging with PET, and to determine its biodistribution and radiation dosimetry using whole-body (WB) PET scans in healthy volunteers. The highest uptake was in the pancreas, followed by urinary bladder. The critical organ was pancreas with a mean absorbed dose of 206 ± 0.7, 210 ± 0.7, 120 ± 0.9, 390.23 ± 0.6 μGy/MBq and the effective doses were estimated as 73.2 ± 0.6, 49.8 ± 0.3 μGy/MBq (women and men, respectively).

Η χαρτογράφηση των πεπτιδικών υποδοχέων που υπερεκφράζονται στην επιφάνεια διαφόρων τύπων καρκινικών κυττάρων έχει αποτελέσει τα τελευταία χρόνια τη βάση για την in vivo μοριακή στόχευση νεοπλασματικών ασθενειών με ραδιοεπισημασμένα πεπτίδια. Το διαρκώς αυξανόμενο ενδιαφέρον αναφορικά με τα ραδιοπεπτίδια αυτά έχει οδηγήσει στο σχεδιασμό αρκετών πεπτιδικών αναλόγων, τα οποία φέροντας το κατάλληλο ραδιονουκλείδιο είναι ικανά να προσφέρουν πολλές δυνατότητες στην εξατομικευμένη διάγνωση και θεραπεία ασθενών. Η παρούσα διατριβή εστιάζει στην ανάπτυξη ραδιοσημασμένων πεπτιδικών GRPR-ανταγωνιστών με διαγνωστικά και θεραπευτικά ραδιονουκλίδια, με βελτιωμένα βιολογικά χαρακτηριστικά, όπως κατάλληλη βιοκινητική και υψηλή μεταβολική σταθερότητα. Πραγματοποιήθηκε σύγκριση της βιολογικής συμπεριφοράς και της φαρμακοκινητικής ενός GRPR-ανταγωνιστή κι ενός αγωνιστή παρόμοιας χημικής δομής. Παράλληλα, έγινε προσπάθεια αύξησης της μεταβολικής σταθερότητας με στοχευμένη δομική τροποποίηση της πεπτιδικής αλληλουχίας ενός GRPR-ανταγωνιστή, ενώ αξιολογήθηκε και η επίδραση διαφορετικών ραδιομετάλλων στη σταθερότητα και τις βιολογικές του ιδιότητες των σχηματιζόμενων ραδιοπεπτιδίων. Αντικείμενο εκτενούς μελέτης αποτέλεσε και ο προσδιορισμός της δράσης του πρωτεολυτικού ενζύμου NEP, η ανάδειξη των σημείων που αποικοδομεί τα ραδιοπεπτιδικά ανάλογα, καθώς και η δυνατότητα αναστολής της δράσης της με στόχο την αύξηση της in vivo μεταβολικής σταθερότητας των ραδιοπεπτιδικών αναλόγων. Στο πλαίσιο αυτό σχεδιάστηκαν και συντέθηκαν δύο νέοι GRPR-ανταγωνιστές, το SB4 και το SB9, ο γνωστός GRPR-ανταγωνιστής SB3, καθώς και τα πιθανά προϊόντα αποικοδόμησης του, μεταβολίτες M1-5. Η σύνθεση τους πραγματοποιήθηκε σύμφωνα με την στρατηγική σύνθεσης σε στερεά φάση με τη μέθοδο προστασίας Fmoc και η ταυτοποίηση τους πραγματοποιήθηκε με RP-HPLC και MALDI-TOF MS. Τα αποτελέσματα των in vitro & in vivo μελετών που πραγματοποιήθηκαν επαλήθευσαν την ανώτερη φαρμακοκινητική και υψηλότερη σταθερότητα για τον GRPR-ανταγωνιστή [111In]SB9 έναντι του αγωνιστή [111In]AMBA, γεγονός που συνάδει με τη γενικότερη αντίληψη ότι οι GRPR-ανταγωνιστές είναι προτιμότεροι από τους αντίστοιχους αγωνιστές για την απεικόνιση και τη θεραπεία καρκινικών όγκων. Επιβεβαιώθηκε ότι η αντικατάσταση της γλυκίνης από D-αλανίνη αποτελεί έναν αποτελεσματικό τρόπο αύξησης της μεταβολικής σταθερότητας, δεδομένου ότι το [111In]SB4 εμφανίστηκε σημαντικά πιο ανθεκτικό από το [111In]SB3 έναντι των πρωτεολυτικών ενζύμων, με αντίκτυπο τη σημαντική μείωση στην ικανότητα δέσμευσης στον GRPR και εν τέλει στην ικανότητα στόχευσης πειραμάτικων όγκων PC-3. Αποδείχθηκε η δυνατότητα για περαιτέρω βελτίωση της φαρμακοκινητική μέσω in situ σταθεροποίησης των ραδιοπεπτιδικών αναλόγων με τη συγχορήγηση PA ως αναστολέα της NEP. Τέλος, ταυτοποιήθηκαν οι θέσεις αποικοδόμησης λόγω της δράσης της NEP για το ραδιοπεπτίδια [111In/177Lu]SB3, μέσω της ταυτοποίησης των αντίστοιχων ραδιομεταβολιτών., Mapping of peptide receptors which overexpressed on the surface of various types of cancer cells has been in recent years the basis for in vivo molecular targeting of neoplastic diseases with radiolabeled peptides. Therefore, a significant number of peptide analogs have been designed to date in order to deliver appropriate diagnostic and therapeutic radionuclides selectively to cancer targets. In this way they offer individualized treatment of cancer for each patient in the context of "molecular diagnosis and treatment". The present thesis focuses on the development of peptide GRPR-antagonists radiolabeled with diagnostic and therapeutic radionuclides with improved biological characteristics, such as high metabolic stability and desirable biokinetics. It has initially included the comparison of biological behavior, with emphasis on pharmacokinetics in mice with human GRPR-positive xenografts, a GRPR-antagonist and an agonist with similar chemical structure. Afterwards, an attempt was made to increase the metabolic stability by targeted structural modification of the peptide sequence of a GRPR-antagonist, while the effect of different radiometals was evaluated on the stability and biological elements of the formed radiopeptides. Finally, subject of extensive study was the determination of the activity of the proteolytic enzyme NEP in a series of radiolabeled GRPR-antagonists, the definition of degradation sites, as well as the possibility of in-situ inhibition of its action in order to increase in vivo metabolic stability. In this context, two new GRPR-antagonists were designed and synthesized, SB4 and SB9, the well-known GRPR antagonist SB3, as well as its potential degradation products, metabolites M1-5. Their synthesis was carried out according to the solid phase synthesis strategy by Fmoc protection method and their identification was performed using RP-HPLC and MALDI-TOF MS. The results of in vitro & in vivo studies verified the superior pharmacokinetic and higher stability for the GRPR-antagonist [111In]SB9 versus the agonist [111In]AMBA, fact which is in consistent with the general perception that GRPR-antagonists are preferable relative to the respective agonists for the imaging and treatment of cancer tumors. Replacement of glycine-11 by D-alanine in the peptide sequence was confirmed as an effective way to increase metabolic stability, considering that [111In]SB4 appeared to be significantly more stable than [111In]SB3. However, this modification had a negative impact on the ability of SB4 to bind to GRPR and after all to the ability of targeting experimental PC-3 tumors for [111In]SB4. Finally, for all analogues, the possibility of further improvement of pharmacokinetics was demonstrated through in situ stabilization of radiopeptide analogues with the co-administration of the NEP inhibitor, PA. By the contribution of the original radiometabolites, which may be formed according to the literature and synthesized for this purpose, and by the application of radioanalytic chromatographic comparison methods, the degradation sites by NEP in the sequence of radiopeptides [111In/177Lu]SB3 were identified.

Three new bifunctional copper chelators based on the 1,4,7-triazacyclononane (tacn) platform have been synthesized and conjugated to peptides. The first one is constituted of the tacn with two methylpyridinyl and one methylthiazolyl carboxylic acid pendant arms, while, in the second and third ones, the macrocycle is functionalized by three methylpyridinyl groups, with an additional hexynoic acid chain on a carbon of one or two pyridine rings. These three bifunctional chelators have been conjugated to the antagonist DPhe-Gln-Trp-Ala-Val-Gly-His-Sta-Leu-NH2 peptide for targeting the gastrin-releasing peptide receptor, which is overexpressed in prostate cancer. The resulting monomeric bioconjugates have shown their efficiency to be radiolabeled with β+ emitter 64Cu, and the hydrophilicity and PC-3 cell internalization properties of these radiolabeled conjugates have been studied. PC-3 cell binding affinity of mono- and dimeric metal-free and natCu metallated conjugates have been evaluated by IC50 measurements. The results demonstrate the potential of these methylpyridinyl tacn derivatives for radiopharmaceutical applications.

Das Proteolipid Neuronatin (Nnat) ist an der Modulation zellulärer Signalwege beteiligt und scheint auch eine Funktion bei der Regulation der Energiehomöostase einzunehmen. Die gastrointestinalen Peptide Cholecystokinin (CCK) und Bombesin (BN) zeigen vor allem hemmende Effekte auf die Kurzzeitregulation der Nahrungsaufnahme, welche durch die Aktivierung verschiedener Hirnkerne wie dem Nucleus Tractus Solitarius (NTS) und dem Dorsalen Motornucleus des Vagus (DMV) vermittelt werden. In dieser Studie sollte untersucht werden, ob Neuronatin in NTS- oder DMV-Neuronen lokalisiert vorliegt und ob CCK-8S oder BN eine c-Fos-Aktivierung von Nnat-Neuronen bewirkt. Nicht-gefastete männliche Sprague Dawley-Ratten erhielten eine intraperitoneale (i.p.) Injektion von 5,2 bzw. 8,7 nmol CCK-8S /kg oder 26 bzw. 32 nmol Bombesin/kg (n=4) oder eine Vehikellösung (0,15 M NaCl, n=7). 90 Minuten nach der Injektion wurde die Anzahl c-Fos-positiver Neuronen im NTS und DMV bestimmt. Sowohl im NTS als auch im DMV wurden Nnat-positive Neuronen beobachtet. CCK-8S (25-fach und 51-fach, p = 0,025 und p = 0,001) und Bombesin (31-fach und 59-fach, p=0,007 und p=0,001) bewirkten in beiden Dosierungen im Vergleich zur Vehikel-Lösung einen signifikanten Anstieg c-Fos-positiver Neuronen im NTS. Im DMV wurde kein signifikanter Effekt der CCK- oder BN-Injektionen festgestellt. Beide Dosen CCK-8S (24-fach und 48-fach, p=0,011 und p=0,001) und Bombesin (31-fach und 56-fach, p=0,002 und p=0,001) führten weiterhin zu einer erhöhten Anzahl aktivierter Nnat-Neuronen im NTS (p=0,001) im Vergleich zur Vehikelgruppe. In der vorliegenden Studie konnte gezeigt werden, dass i.p. injiziertes CCK-8S oder Bombesin eine erhöhte neuronale Aktivität in Nnat-Neuronen des NTS induzieren. Dieses Ergebnis deutet darauf hin, dass Nnat an der CCK-8S- und Bombesin-vermittelten Regulation der Nahrungsaufnahme beteiligt sein könnte., The proteolipid Neuronatin (Nnat) takes part in the regulation of cellular molecular signaling and also seems to be involved into regulation of energy homoestasis. The gastrointestinal peptides, cholecystokinin (CCK) and bombesin (BN), show an effect on the short-term inhibition of food intake. They induce neural activation in several brain nuclei, especially in the nucleus of the solitary tract (NTS) and the dorsal motor nucleus of the vagus (DMV), which are involved in the regulation of food intake. The aim of the study was to determine whether Nnat immunoreactivity can be detected in the NTS and the DMV, and if the peripheral injection of CCK-8S or BN causes c-Fos activation of Nnat neurons. Non-fasted male Sprangue-Dawley rats were treated with an intraperitoneal (i.p.) injection of 5.2 or 8.7 nmol CCK-8S/kg, 26 or 32 nmol BN/kg (n=4 all groups), or vehicle solution (0.15M NaCl; n=7). 90 minutes after the injection, the number of c-Fos neurons was determined in the NTS and DMV. In the NTS, as well as in the DMV, we detected Nnat immunoreactive neurons. CCK-8S (25-fold and 51-fold, p = 0.025 and p = 0.001) and BN (31-fold and 59-fold, p = 0.007 and p = 0.001) at both doses caused a significantly increased number of c-Fos positive neurons in the NTS compared to the vehicle group. In the DMV we observed no significant effect of CCK or BN injection. Both doses of CCK-8S (24-fold and 48-fold p=0.011 and p=0.001) and BN (31-fold and 56-fold, p=0.002 and p=0.001) also showed an increase of activated Nnat neurons in the NTS (p=0.001) compared to the vehicle group. In conclusion, the i.p. injection of CCK-8S or BN induces a higher neuronal activity in NTS Nnat neurons, suggesting that Nnat may take part in the regulation of food intake mediated by peripheral CCK-8S or BN.

Bombesin (BN) is an itch-specific mediator that causes intense itch-scratching activity in mammals. Although most examinations of BN-induced itch processing have focused on the spinal cord, the involvement of central nervous system mechanisms remains unclear. Here, we investigated how relationships among hypothalamic regions regulate BN-mediated itch-scratch processes. We found that intracerebroventricular (i.c.v.) administration of BN (0.04-4 μg) elicited intense itch scratching in mice, whereas BN (0.4-400 μg) administered via intravenous tail injection failed to evoke a scratching response. Additionally, nalfurafine had no significant effects on BN-induced scratching behavior, indicating that central modulation of BN is distinct from histamine-mediated histaminergic itch and chloroquine-mediated non-histaminergic itch signaling pathways. We labeled BN with a fluorescent tag, 7-nitrobenz-2-oxa-1 (NBD), and traced its fluorescence in the hypothalamus for 30 min following i.c.v. NBD-BN administration. Accordingly, we confirmed that i.c.v. administration of BN enhanced c-Fos expression in the dorsal medial nucleus of the hypothalamus, where neuromedin B receptors and gastrin-releasing peptide receptors are highly expressed. Interestingly, in situ injection of BN into the hypothalamus immediately and robustly induced itch-scratching behavior. Moreover, gene transcripts and western blot assay revealed that BN receptor-dependent PKA/CREB signaling was upregulated in the hypothalamus after i.c.v. administration of BN. Consistently, pretreatment with a PKA inhibitor, Rp-cAMP, significantly reduced BN-induced scratching behavior. Our results indicate that the dorsal medial nucleus of the hypothalamus may be a key nucleus in mediating BN-mediated itch and hypothalamic PKA/CREB signaling is involved in regulating BN-mediated itch.

Simple Summary Recent medical advancements have strived for a personalized medicine approach to patients, aimed at optimizing therapy outcomes with minimum toxicity. In this respect, nuclear medicine methodologies have been playing increasingly important roles. For example, the overexpression of peptide receptors, such as the gastrin-releasing peptide receptor (GRPR), on tumor cells as opposed to their lack of expression in healthy surrounding tissues can be elegantly exploited with the aid of “smart” peptide carriers, such as the analogs of the amphibian 14-peptide bombesin (BBN). These molecules can bring clinically attractive radionuclides to malignant lesions in prostate, breast, and other human cancers, sparing healthy tissues. Depending upon the radionuclide in question, diagnostic imaging with single-photon emission computed tomography (SPECT) or positron emission tomography (PET) has been pursued, identifying patients who are eligible for peptide radionuclide receptor therapy (PRRT) in an integrated “theranostic” approach. In the present review, we (i) discuss the major steps taken in the development of anti-GRPR theranostic radioligands, with a focus on those selected for clinical testing; (ii) comment on the present status in this field of research; and (iii) reflect on the current limitations as well as on new opportunities for their broader and more successful clinical applications. Abstract The gastrin-releasing peptide receptor (GRPR) is expressed in high numbers in a variety of human tumors, including the frequently occurring prostate and breast cancers, and therefore provides the rationale for directing diagnostic or therapeutic radionuclides on cancer lesions after administration of anti-GRPR peptide analogs. This concept has been initially explored with analogs of the frog 14-peptide bombesin, suitably modified at the N-terminus with a number of radiometal chelates. Radiotracers that were selected for clinical testing revealed inherent problems associated with these GRPR agonists, related to low metabolic stability, unfavorable abdominal accumulation, and adverse effects. A shift toward GRPR antagonists soon followed, with safer analogs becoming available, whereby, metabolic stability and background clearance issues were gradually improved. Clinical testing of three main major antagonist types led to promising outcomes, but at the same time brought to light several limitations of this concept, partly related to the variation of GRPR expression levels across cancer types, stages, previous treatments, and other factors. Currently, these parameters are being rigorously addressed by cell biologists, chemists, nuclear medicine physicians, and other discipline practitioners in a common effort to make available more effective and safe state-of-the-art molecular tools to combat GRPR-positive tumors. In the present review, we present the background, current status, and future perspectives of this endeavor.

SummaryDisinhibitory neurons throughout the mammalian cortex are powerful enhancers of circuit excitability and plasticity. The differential expression of neuropeptide receptors in disinhibitory, inhibitory and excitatory neurons suggests that each circuit motif is controlled by distinct neuropeptidergic systems. Here, we reveal that a bombesin-like neuropeptide, gastrin-releasing peptide (GRP), recruits disinhibitory cortical microcircuits through selective targeting and activation of vasoactive intestinal peptide (VIP)-expressing cells. Using a newly-developed genetically-encoded GRP sensor and trans-synaptic tracing we reveal that GRP regulates VIP cells via extrasynaptic diffusion from several putative local and long-range sources. In vivo photometry and CRISPR/Cas9-mediated knockout of the GRP receptor (GRPR) in auditory cortex indicate that VIP cells are strongly recruited by novel sounds and aversive shocks, and that GRP-GRPR signaling enhances auditory fear memories. Our data establish peptidergic recruitment of selective disinhibitory cortical microcircuits as a mechanism to regulate fear memories.

As a novel type of theranostic radioactive agents

Theeranan Tangthong,1,2 Thananchai Piroonpan,2 Velaphi C Thipe,3,4 Menka Khoobchandani,4,5 Kavita Katti,4,5 Kattesh V Katti,4– 6 Wanvimol Pasanphan1,2 1Department of Materials Science, Faculty of Science, Kasetsart University, Chatuchak, Bangkok, 10900, Thailand; 2Center of Radiation Processing for Polymer Modification and Nanotechnology (CRPN), Department of Materials Science, Faculty of Science, Kasetsart University Chatuchak, Bangkok, 10900, Thailand; 3Department of Chemistry, University of Missouri, Columbia, MO, 65211, USA; 4Institute of Green Nanotechnology, University of Missouri, Columbia, MO, 65211, USA; 5Department of Radiology, University of Missouri, Columbia, MO, 65211, USA; 6Department of Physics, University of Missouri, Columbia, MO, 65211, USACorrespondence: Wanvimol PasanphanDepartment of Materials Science, Faculty of Science, Kasetsart University, 50 Ngam Wong Wan Road, Lat Yao, Chatuchak, Bangkok, 10900, ThailandTel +66 2562 5555 (Ext. 646518)Email wanvimol.p@ku.ac.thKattesh V KattiInstitute of Green Nanotechnology, University of Missouri, Columbia, MO, 65211, USATel +1 573 882-5656Fax +1 573 884-5679Email KattiK@health.missouri.eduPurpose: We report herein bombesin peptide conjugated water-soluble chitosan gallate as a template for rapid one-pot synthesis of gold nanoparticles (AuNPs) with capabilities to target receptors on prostate cancer cells.Methods: Water-soluble chitosan (WCS), anchored with gallic acid (GA) and LyslLys3 (1,4,7,10-tetraazacyclo dodecane-1,4,7,10-tetraacetic acid) bombesin 1– 14 (DBBN) peptide, provides a tumor targeting nanomedicine agent. WCS nanoplatforms provide attractive strategies with built-in capabilities to reduce gold (III) to gold nanoparticles with stabilizing and tumor-targeting capabilities. WCS-GA-DBBN encapsulation around gold nanoparticles affords optimum in vitro stability.Results: The DBBN content in the WCS-GA-DBBN sample was ∼ 27%w/w. The antioxidant activities of WCS-GA and WCS-GA-DBBN nanocolloids were enhanced by 12 times as compared to the nascent WCS. AuNPs with a desirable hydrodynamic diameter range of 40– 60 nm have been efficiently synthesized using WCS-GA and WCS-GA-DBBN platforms. The AuNPs were stable over 4 days after preparation and ∼ 3 days after subjecting to all relevant biological fluids. The AuNPs capped with WCS-GA-DBBN peptide exhibited superior cellular internalization into prostate tumor (PC-3) cells with evidence of receptor mediated endocytosis.Conclusion: The AuNPs capped with WCS-GA-DBBN exhibited selective affinity toward prostate cancer cells. AuNPs conjugated with WCS-GA-DBBN serve as a new generation of theranostic agents for treating various neoplastic diseases, thus opening-up new applications in oncology.Keywords: water-soluble chitosan, gallic acid, bombesin, one-pot synthesis, gold nanoparticle, prostate cancer