Clinical application of Fluciclovine PET, choline PET and gastrin-releasing polypeptide receptor (bombesin) targeting PET in prostate cancer.

PURPOSE OF REVIEW: The aim of this review is to explore the clinical application of different PET radiopharmaceuticals in prostate cancer (PCa), beyond inhibitors of the prostate-specific membrane antigen (PSMA). RECENT FINDINGS: Choline PET represented in the last decades the standard of reference for PET imaging in PCa and has been recently included in clinical trials evaluating the efficacy of metastasis-directed therapy in oligo-metastatic disease. Fluciclovine, as synthetic amino acid, has been proposed for investigating PCa. The results obtained by the first prospective studies led to FDA approval in 2016 in patients with biochemical recurrence. Recently, phase II/III trials explored its accuracy compared with PSMA PET and its impact on patient management. Imaging the gastrin-releasing polypeptide receptor (GRPR) recently drawn attention. Radio-labelled GRPR antagonists have the potential to be used as theranostic agents. Further evaluation is needed to understand the relation between GRPR expression and hormonal-resistant PCa, and for tumors characterized by heterogeneity of receptors expressed (e.g. PSMA-negative) on their cell surface. SUMMARY: Other new generation PET tracers may play an important role in PCa, namely in case of PSMA-negative phenotypes.

Antidiabetic effects and sustained metabolic benefits of sub-chronic co-administration of exendin-4/gastrin and xenin-8-Gln in high fat fed mice.

The present study has examined the antidiabetic effects of 21 days co-administration of xenin-8-Gln with the dual-acting fusion peptide, exendin-4/gastrin, as well as persistence of beneficial metabolic benefits, in high fat fed (HFF) mice. Xenin-8-Gln, exendin-4 and gastrin represent compounds that activate receptors of the gut-derived hormones, xenin, glucagon-like peptide-1 (GLP-1) and gastrin, respectively. Twice-daily administration of exendin-4/gastrin, xenin-8-Gln or a combination of both peptides significantly reduced circulating glucose, HbA1c and cumulative energy intake. Combination therapy with xenin-8-Gln and exendin-4/gastrin increased circulating insulin. All HFF mice treated with exendin-4/gastrin presented with body weight similar to lean control mice on day 21. Each treatment improved glucose tolerance and the glucose-lowering actions of glucose dependent insulinotropic polypeptide (GIP), as well as augmenting glucose- and GIP-induced insulin secretion, with benefits being most prominent in the combination group. Administration of exendin-4/gastrin alone, and in combination with xenin-8-Gln, increased pancreatic insulin content and improved the insulin sensitivity index. Pancreatic beta-cell area was significantly increased, and alpha cell area decreased, by all treatments, with the combination group also displaying enhanced overall islet area. Notably, metabolic benefits were generally retained in all groups of HFF mice, and especially in the combination group, following discontinuation of the treatment regimens for 21 days. This was associated with maintenance of increased islet and beta-cell areas. Together, these data confirm the antidiabetic effects of co-activation of GLP-1, gastrin and xenin cell signalling pathways, and highlight the sustainable benefits this type of treatment paradigm can offer in T2DM.

Targeted Magnetic Intra-Lysosomal Hyperthermia produces lysosomal reactive oxygen species and causes Caspase-1 dependent cell death.

Therapeutic strategies using drugs which cause Lysosomal Cell Death have been proposed for eradication of resistant cancer cells. In this context, nanotherapy based on Magnetic Intra-Lysosomal Hyperthermia (MILH) generated by magnetic nanoparticles (MNPs) that are grafted with ligands of receptors overexpressed in tumors appears to be a very promising therapeutic option. However, mechanisms whereby MILH induces cell death are still elusive. Herein, using Gastrin-grafted MNPs specifically delivered to lysosomes of tumor cells from different cancers, we provide evidences that MILH causes cell death through a non-apoptotic signaling pathway. The mechanism of cell death involves a local temperature elevation at the nanoparticle periphery which enhances the production of reactive oxygen species through the lysosomal Fenton reaction. Subsequently, MILH induces lipid peroxidation, lysosomal membrane permeabilization and leakage of lysosomal enzymes into the cytosol, including Cathepsin-B which activates Caspase-1 but not apoptotic Caspase-3. These data highlight the clear potential of MILH for the eradication of tumors overexpressing receptors.

Z-360 Suppresses Tumor Growth in MIA PaCa-2-bearing Mice via Inhibition of Gastrin-induced Anti-Apoptotic Effects.

BACKGROUND/AIM: The aim of the study was to evaluate the anti-tumor mechanism of Z-360, a gastrin/cholecystokinin-2 receptor (CCK2R) antagonist, in MIA PaCa-2 cells and in a subcutaneous xenograft mice model. MATERIALS AND METHODS: The anti-tumor effects of Z-360 and/or gemcitabine were monitored using a MIA PaCa-2 xenograft model. The effect of Z-360 on apoptosis in the model was examined by TUNEL staining and real-time PCR analysis and the effect in MIA PaCa-2 cells stably expressing human CCK2R was also evaluated by caspase-3/7 activity. RESULTS: In this xenograft model, Z-360 significantly reduced the tumor weight, increased TUNEL-positive cells and suppressed the expression of anti-apoptosis factors such as survivin, XIAP and Mcl-1, and these effects of Z-360 combined with gemcitabine were more effective. Furthermore, gastrin-17 and gastrin-34 inhibited apoptosis in vitro and Z-360 dose-dependently abrogated this effect. CONCLUSION: These results suggest that Z-360 exerts an anti-tumor effect through a reduction in anti-apoptosis factors by blocking CCK2R.

Growth factors and medium hyperglycemia induce Sox9+ ductal cell differentiation into ß cells in mice with reversal of diabetes.

We previously reported that long-term administration of a low dose of gastrin and epidermal growth factor (GE) augments ß-cell neogenesis in late-stage diabetic autoimmune mice after eliminating insulitis by induction of mixed chimerism. However, the source of ß-cell neogenesis is still unknown. SRY (sex-determining region Y)-box 9(+) (Sox9(+)) ductal cells in the adult pancreas are clonogenic and can give rise to insulin-producing ß cells in an in vitro culture. Whether Sox9(+) ductal cells in the adult pancreas can give rise to ß cells in vivo remains controversial. Here, using lineage-tracing with genetic labeling of Insulin- or Sox9-expressing cells, we show that hyperglycemia (>300 mg/dL) is required for inducing Sox9(+) ductal cell differentiation into insulin-producing ß cells, and medium hyperglycemia (300-450 mg/dL) in combination with long-term administration of low-dose GE synergistically augments differentiation and is associated with normalization of blood glucose in nonautoimmune diabetic C57BL/6 mice. Short-term administration of high-dose GE cannot augment differentiation, although it can augment preexisting ß-cell replication. These results indicate that medium hyperglycemia combined with long-term administration of low-dose GE represents one way to induce Sox9(+) ductal cell differentiation into ß cells in adult mice.

A multicenter phase II study of G17DT immunogen plus irinotecan in pretreated metastatic colorectal cancer progressing on irinotecan.

BACKGROUND: The G17DT is a novel human immunogen that raises antibodies to the growth factor gastrin 17 (G17). The purpose of this study was to determine the safety and efficacy of G17DT in combination with irinotecan in patients refractory to irinotecan, and to correlate efficacy with anti-G17 immune response. METHODS: Patients received G17DT immunogen as a single intramuscular injection of 500 µg at weeks 1, 5, 9, and 26. Irinotecan was administered as an intravenous infusion of 125 mg/m(2) over 90 min starting at week 5. Each cycle of treatment consisted of irinotecan administered once weekly for 4 weeks, followed by a 2-week rest period. RESULTS: Of 161 patients who received G17DT, the best overall tumor response in the intent-to-treat population was complete response 0 (0 %), partial response 3 (3 %), stable disease 32 (32 %), and progressive disease 64 (65 %). Median survival was 217 days. About 94 (62 %) subjects evaluable for antibody titers were anti-G17 responders. Survival was significantly longer for anti-G17 responders compared with non-responders (9.0 vs. 5.6 months; P < 0.001). Toxicity was consistent with irinotecan (diarrhea, nausea, anemia, vomiting, fatigue, constipation, anorexia, and neutropenia) except for injection site reactions (pain 42 %, induration 13 %, edema 11 %, erythema 10 %, and three abscesses) attributed to G17DT in 52 % of the patients. CONCLUSION: Treatment with G17DT in combination with irinotecan results in an acceptable anti-G17 immune response, which correlated with promising survival activity in patients refractory to irinotecan-based chemotherapy.

Indian Hedgehog mediates gastrin-induced proliferation in stomach of adult mice.

BACKGROUND & AIMS: Loss of expression of Sonic Hedgehog (Shh) from parietal cells results in hypergastrinemia in mice, accompanied by increased expression of Indian Hedgehog (Ihh) and hyperproliferation of surface mucous cells. We investigated whether hypergastrinemia induces gastric epithelial proliferation by activating Ihh signaling in mice. METHODS: We studied mice with parietal cell-specific deletion of Shh (PC-Shh(KO)) and hypergastrinemia, crossed with gastrin-deficient (GKO) mice (PC-Shh(KO)/GKO). When mice were 3-4 months old, gastric tissues were collected and analyzed by histology, for incorporation of bromodeoxyuridine, and for expression of the surface mucous cell marker Ulex europaeus. PC-Shh(KO)/GKO mice were given gastrin infusions for 7 days; gastric surface epithelium was collected and expression of Ihh was quantified by laser capture microdissection followed by quantitative reverse transcriptase polymerase chain reaction. Mouse stomach-derived organoids were incubated with or without inhibitors of WNT (DKK1) or Smoothened (vismodegib) and then cocultured with immortalized stomach mesenchymal cells, to assess proliferative responses to gastrin. RESULTS: Gastric tissues from PC-Shh(KO)/GKO mice with hypergastrinemia had an expanded surface pit epithelium, indicated by a significant increase in numbers of bromodeoxyuridine- and Ulex europaeus-positive cells, but there was no evidence for hyperproliferation. Gastrin infusion of PC PC-Shh(KO)/GKO mice increased expression of Ihh and proliferation within the surface epithelium compared with mice given infusions of saline. In gastric organoids cocultured with immortalized stomach mesenchymal cells, antagonists of WNT and Smoothened inhibited gastrin-induced proliferation and WNT activity. Activity of WNT in media collected from immortalized stomach mesenchymal cells correlated with increased expression of glioma-associated oncogene homolog 1, and was inhibited by DKK1 or vismodegib. CONCLUSIONS: Ihh signaling mediates gastrin-induced proliferation of epithelial cells in stomachs of adult mice.

Omeprazole and PGC-formulated heparin binding epidermal growth factor normalizes fasting blood glucose and suppresses insulitis in multiple low dose streptozotocin diabetes model.

PURPOSE: Our objective was to develop novel nanocarriers (protected graft copolymer, PGC) that improve the stability of heparin binding EGF (HBEGF) and gastrin and then to use PGC-formulated HBEGF (PGC-HBEGF) and Omeprazole (+/- PGC-gastrin) for normalizing fasting blood glucose (FBG) and improving islet function in diabetic mice. METHODS: HBEGF, PGC-HBEGF, Omeprazole, Omeprazole + PGC-HBEGF, Omeprazole + PGC-gastrin + PGC-HBEGF and epidermal growth factor (EGF) + gastrin were tested in multiple low dose streptozotocin diabetic mice. RESULTS: Omeprazole + PGC-HBEGF normalized FBG and is better than EGF + gastrin at improving islet function and decreasing insulitis. Groups treated with Omeprazole, Omeprazole + PGC-HBEGF, or EGF + gastrin have significantly improved islet function versus saline control. All animals that received PGC-HBEGF had significantly reduced islet insulitis versus saline control. Non-FBG was lower for Omeprazole + PGC-gastrin + PGC-HBEGF but Omeprazole + PGC-HBEGF alone showed better FBG and glucose tolerance. CONCLUSIONS: Omeprazole + PGC-HBEGF provides a sustained exposure to both EGFRA and gastrin, improves islet function, and decreases insulitis in multiple low dose streptozotocin diabetic mice. Although HBEGF or EGF elevates non-FBG, it facilitates a reduction of insulitis and, in the presence of Omeprazole, provides normalization of FBG at the end of treatment. The study demonstrates Omeprazole and PGC-HBEGF is a viable treatment for diabetes.

Gastrin-induced proliferation involves MEK partner 1 (MP1).

The peptide hormone gastrin is an important factor for the maintenance and homeostasis of the gastric mucosa. We show that gastrin stimulates proliferation in a dose-dependent manner in the human gastric adenocarcinoma cell line AGS-GR. Furthermore, we demonstrate that the MAPK scaffold protein MEK partner 1 (MP1) is important for gastrin-induced phosphorylation of ERK1 and ERK2 and that MP1 promotes gastrin-induced proliferation of AGS-GR cells. Our results suggest a role of MP1 in gastrin-induced cellular responses involved in proliferation and homeostasis of the gastric mucosa.

Mixed chimerism and growth factors augment ß cell regeneration and reverse late-stage type 1 diabetes.

Type 1 diabetes (T1D) results from an autoimmune destruction of insulin-producing ß cells. Currently, islet transplantation is the only curative therapy for late-stage T1D, but the beneficial effect is limited in its duration, even under chronic immunosuppression, because of the chronic graft rejection mediated by both auto- and alloimmunity. Clinical islet transplantation is also restricted by a severe shortage of donor islets. Induction of mixed chimerism reverses autoimmunity, eliminates insulitis, and reverses new-onset but not late-stage disease in the nonobese diabetic (NOD) mouse model of T1D. Administration of gastrin and epidermal growth factor (EGF) also reverses new-onset but not late-stage T1D in this animal model. Here, we showed that combination therapy of induced mixed chimerism under a radiation-free nontoxic anti-CD3/CD8 conditioning regimen and administration of gastrin/EGF augments both ß cell neogenesis and replication, resulting in reversal of late-stage T1D in NOD mice. If successfully translated into humans, this combination therapy could replace islet transplantation as a long-term curative therapy for T1D.

Epidermal growth factor and gastrin on PDX1 expression in experimental type 1 diabetic rats.

INTRODUCTION: The aim of this study was to investigate whether combined epidermal growth factor (EGF) and gastrin can correct the hyperglycemia induced by streptozotocin (STZ) in rats and to determine the involvement of the transcription factor pancreatic and duodenal homeobox 1 (PDX1) in this process. METHODS: Rat diabetes was induced by intraperitoneal injection of STZ. The mRNA and protein levels of insulin and PDX1 were determined by real-time reverse transcriptase polymerase chain reaction and immunohistochemistry. Serum levels of C-peptide and insulin were analyzed using radioimmunoassay kits. RESULTS: The combined administration of EGF and gastrin efficiently reversed the hyperglycemia induced by STZ. Elevated insulin concentration was detected in diabetic rats treated with EGF plus gastrin. The authors also found that both insulin and PDX1 expression were reduced in STZ-treated rats. Interestingly, the combination treatment also significantly enhanced the mRNA levels of insulin and PDX1, and that of their protein products. CONCLUSIONS: Therapy with EGF plus gastrin corrected hyperglycemia and maintained insulin content in STZ-induced diabetic rats via up-regulation of PDX1 expression, suggesting that this combination treatment may provide a valuable approach for pancreatic islet neogenesis in vivo.

Sulfated gastrin stimulates ghrelin and growth hormone release but inhibits insulin secretion in cattle.

This study was designed to determine the effects of gastrin on the circulating levels of ghrelin, growth hormone (GH), insulin, glucagon and glucose in ruminants. Two experiments were done in eight Holstein steers. Animals were randomly assigned to receive intravenous bolus injections: (1) 0.1% bovine serum albumin in saline as vehicle, 0.8, 4.0 and 20.0 µg/kg body weight (BW) of bovine sulfated gastrin-34; (2) vehicle, 0.53 µg/kg BW of bovine sulfated gastrin-17 alone or combined with 20.0 µg/kg BW of [D-Lys(3)]-GHRP-6, the selective antagonist of GHS-R1a. Blood samples were collected from -10 to 150 min relative to injection time. Concentrations of acyl and total ghrelin in response to gastrin-34 injection were significantly increased in a dose-dependent manner. Concentrations of GH were also markedly elevated by gastrin-34 injection; however, the effect of 20.0 µg/kg was weaker than that of 4.0 µg/kg. The three doses of gastrin-34 equally decreased insulin levels within 15 min and maintained the level until the time of last sampling. Gastrin-34 had no effect (P > 0.05) on the levels of glucagon and glucose. Levels of acyl ghrelin increased after administration of gastrin-17 alone or combined with [D-Lys(3)]-GHRP-6; however, [D-Lys(3)]-GHRP-6 did not block the elevation of GH by gastrin-17. The present results indicate that sulfated gastrin stimulates both ghrelin and GH release, but the GHS-R1a may not contribute to the release of GH by gastrin. Moreover, sulfated gastrin seems to indirectly maintain the homeostasis of blood glucose through the down-regulation of insulin in ruminants.

Gastric type I carcinoid: a pilot study with human G17DT immunogen vaccination.

CONTEXT: Gastric type I carcinoid is a rare neoplasm, deriving from enterochromaffin-like cells (ECL), mainly affecting women with autoimmune gastritis. The approach to treatment, either endoscopic, medical or surgical, is not well defined, particularly in multifocal tumours or carcinoids with rapid growth/frequent recurrence. OBJECTIVE: To determine whether an anti-G17 vaccination might interfere on the natural history of gastric type I carcinoid. SETTING: Padua teaching Hospital, outpatient clinic. DESIGN AND PATIENTS: Three patients with type I gastric carcinoid in autoimmune gastritis were administered, after informed consent and ethic committee approval, with a vaccine against gastrin 17 (G17), a synthetic peptide that stimulates specific and high-affinity anti-G17 antibodies, and followed up endoscopically and clinically for a mean of 36 months. MAIN OUTCOME MEASURES: Gastric histology and specifically carcinoid growth/recurrence and trend in time in gastrin, G17, pepsinogens, chromogranin A and clinical parameters. RESULTS: Following vaccination, carcinoid regression was observed in 2/3 patients and, in one of the patients, even the disappearance of ECL hyperplasia, with a reduced ECL cells stimulation, confirmed by a significant reduction in chromogranin A levels. Regression was observed in the two patients that showed a more clear local response to the vaccine. Increased autoantibody titre was observed, but no appearance of new autoimmune diseases. CONCLUSIONS: Anti-G17 vaccination induced regression of type I gastric carcinoid and could be considered for the treatment of this tumour, when endoscopic removal is not indicated.

Intracoronary gastrin 17 increases cardiac perfusion and function through autonomic nervous system, CCK receptors, and nitric oxide in anesthetized pigs.

The release of gastrointestinal hormones has been reported to modulate reflex cardiovascular responses caused by gastric distension, although the role played by gastrin 17 is as yet unknown. The present study was therefore planned to determine the primary in vivo effect of gastrin 17 on coronary blood flow and cardiac function and the involvement of autonomic nervous system, CCK1/2 receptors, and nitric oxide (NO). In 40 anesthetized pigs, gastrin 17 was infused into the left anterior descending coronary artery at constant heart rate and arterial blood pressure. In 35 of the 40 pigs, the mechanisms of the observed hemodynamic responses were analyzed by repeating gastrin 17 infusion after autonomic nervous system and NO blockade, and after specific CCK receptors agonists/antagonists administration. Intracoronary gastrin 17 administration caused dose-related increases of both coronary blood flow and cardiac function. The intracoronary co-administration of CCK33/pentagastrin and gastrin 17 potentiated the coronary effects observed when the above agents were given alone (P <0.05). The potentiation of the cardiac response was observed only with the co-administration of pentagastrin and gastrin 17 (P <0.05). Moreover, blockade of muscarinic cholinoceptors (intravenous atropine) and of α-adrenoceptors (intravenous phentolamine) did not abolish the hemodynamic responses to gastrin 17. The cardiac and vascular effects of the hormone were prevented by blockade of ß-adrenoceptors (intravenous atenolol and butoxamine), CCK1/2 receptors (intracoronary lorglumide and CAM-1028), and NO synthase (intracoronary Nω-nitro-l-arginine methyl ester). In conclusion, gastrin 17 primarily increased coronary blood flow and cardiac function through the involvement of CCK receptors, ß-adrenoceptors, and NO release.

Comparison of the actions of acylated and desacylated ghrelin on acid secretion in the rat stomach.

BACKGROUND: Ghrelin, a growth-hormone-releasing peptide, has two major molecular forms: acylated (acyl) and desacylated (desacyl). Recent studies suggest different roles for these two forms. In the present study, we compared desacyl and acyl ghrelin with regard to acid secretion and histamine production in the rat stomach. METHODS: We performed in vivo experiments using gastric lumen-perfused rats. The effects of the two forms of ghrelin on gastrin (gastrin-17)-stimulated acid secretion were also examined. Furthermore, to examine the effects of ghrelin on histamine production, histidine decarboxylase messenger ribonucleic acid in the gastric corpus mucosa was measured by reverse transcription-polymerase chain reaction. RESULTS: Intravenous administration of acyl ghrelin at 20 µg/kg increased gastric acid secretion to 4.8 times greater than control levels. However, desacyl ghrelin had no effect on acid secretion, even at 200 µg/kg. Acyl ghrelin enhanced gastrin-stimulated acid secretion while desacyl ghrelin did not. Vagotomy markedly inhibited the enhancement of gastrin-stimulated acid secretion by acyl ghrelin. Acyl ghrelin increased histidine decarboxylase messenger ribonucleic acid concentration by 2.3 times compared with basal levels at 1 h after administration and by 2.7 times at 2 h after administration; desacyl ghrelin had no such effect. Synergism between acyl ghrelin and gastrin was seen regarding histidine decarboxylase messenger ribonucleic acid concentration. CONCLUSIONS: The results indicate that acyl ghrelin stimulates gastric acid secretion via a mechanism involving activation of the vagus nerve and histamine release and synthesis and that desacyl ghrelin has no action on gastric acid secretion. Furthermore, the results demonstrate synergism between gastrin and acyl ghrelin in terms of gastric acid secretion via a mechanism involving histamine release and synthesis.

Stimulation of proliferation in the colorectal mucosa by gastrin precursors is blocked by desferrioxamine.

Precursors of the peptide hormone gastrin stimulate proliferation in the colorectal mucosa and promote the development of colorectal carcinoma. Gastrins bind two ferric ions selectively and with high affinity, and the biological activity of glycine-extended gastrin (Ggly) in vitro is dependent on the presence of ferric ions. The aim of the present study was to determine whether or not iron is required for biological activity of progastrin and Ggly in vivo. Rats that had undergone a colostomy were infused with Ggly, and proliferation was measured in the defunctioned rectal mucosa. Proliferation was also measured in the colonic mucosa of hGAS and MTI-Ggly mice, which, by definition, overexpress progastrin and Ggly, respectively. The requirement for iron was assessed by thrice-weekly injection of the chelating agent desferrioxamine (DFO). The proliferation index in the defunctioned rectal mucosa was significantly increased in the Ggly-infused rats, and the increase was significantly reduced after treatment with DFO. Treatment with DFO significantly reduced the crypt height and proliferation index in the colonic mucosa of hGAS and MTI-Ggly mice but had no effect on the same variables in wild-type mice. These observations are consistent with the hypothesis that the biological activity of progastrin and Ggly in vivo is dependent on the presence of ferric ions and further suggest that chelating agents may block the stimulatory effects of gastrin precursors in the development of colorectal carcinoma.

Combination therapy with glucagon-like peptide-1 and gastrin restores normoglycemia in diabetic NOD mice.

OBJECTIVE: Glucagon-like peptide-1 (GLP-1) and gastrin promote pancreatic beta-cell function, survival, and growth. Here, we investigated whether GLP-1 and gastrin can restore the beta-cell mass and reverse hyperglycemia in NOD mice with autoimmune diabetes. RESEARCH DESIGN AND METHODS: Acutely diabetic NOD mice were treated with GLP-1 and gastrin, separately or together, twice daily for 3 weeks. Blood glucose was measured weekly and for a further 5 weeks after treatments, after which pancreatic insulin content and beta-cell mass, proliferation, neogenesis, and apoptosis were measured. Insulin autoantibodies were measured, and adoptive transfer of diabetes and syngeneic islet transplant studies were done to evaluate the effects of GLP-1 and gastrin treatment on autoimmunity. RESULTS: Combination therapy with GLP-1 and gastrin, but not with GLP-1 or gastrin alone, restored normoglycemia in diabetic NOD mice. The GLP-1 and gastrin combination increased pancreatic insulin content, beta-cell mass, and insulin-positive cells in pancreatic ducts, and beta-cell apoptosis was decreased. Insulin autoantibodies were reduced in GLP-1- and gastrin-treated NOD mice, and splenocytes from these mice delayed adoptive transfer of diabetes in NOD-scid mice. Syngeneic islet grafts in GLP-1 -and gastrin-treated NOD mice were infiltrated by leukocytes with a shift in cytokine expression from interferon-gamma to transforming growth factor-beta1, and beta-cells were protected from apoptosis. CONCLUSIONS: Combination therapy with GLP-1 and gastrin restores normoglycemia in diabetic NOD mice by increasing the pancreatic beta-cell mass and downregulating the autoimmune response.

Synergistic action of gastrin and ghrelin on gastric acid secretion in rats.

Gastrin and ghrelin are secreted from G cells and X/A-like cells in the stomach, respectively, and respective hormones stimulate gastric acid secretion by acting through histamine and the vagus nerve. In this study, we examined the relationship between gastrin, ghrelin and gastric acid secretion in rats. Intravenous (iv) administration of 3 and 10 nmol of gastrin induced transient increases of ghrelin levels within 10 min in a dose-dependent manner. Double immunostaining for ghrelin and gastrin receptor revealed that a proportion of ghrelin cells possess gastrin receptors. Although (iv) administration of gastrin or ghrelin induced significant gastric acid secretion, simultaneous treatment with both hormones resulted in a synergistic, rather than additive, increase of gastric acid secretion. This synergistic increase was not observed in vagotomized rats. These results suggest that gastrin may directly stimulate ghrelin release from the stomach, and that both hormones may increase gastric acid secretion synergistically.

Persistence of residual beta cells and islet autoimmunity during increasing duration of diabetes in NOD mice and experimental approaches toward reversing new-onset disease with bioactive peptides.

The precise fate of beta cells and the presence of islet infiltrates after onset of type 1 diabetes have not yet been fully characterized. Recently we showed that in newly diabetic NOD mice an appreciable number of beta cells remain. This was also observed during the first 2 weeks of diabetes in NOD mice without treatment with insulin. However, the mean number of beta cells per unit islet cross-sectional area decreased with increasing duration of disease. In contrast, glucagon and somatostatin cell numbers showed an increase. The persistence of insulitis in several islets until 4 weeks of diabetes suggests ongoing beta cell autoimmunity over a protracted phase. Combined daily treatment of newly diabetic NOD mice with epidermal growth factor (EGF) and gastrin for the first 14 days of diabetes resulted in temporary restoration of normoglycemia in 7 of 15 mice. We speculate that the residual beta cells present soon after onset of diabetes may respond to experimental regeneration. Treatment of newly diabetic NOD mice with the bioactive peptides EGF and gastrin resulted in partial and temporary reversal of diabetes. We propose that peptide therapies combined with other benign immunomodulatory approaches to rescue and preserve beta cells in the long term and to prevent recurring autoimmunity may be more effective than peptide therapy alone in reversing diabetes in NOD mice.

[The use of a new analogue DGlu-Octagastrin in scintigraphy of medullary thyroid carcinoma]. / Zastosowanie nowego analogu DGlu-Oktagastryny w scyntygrafii raka rdzeniatego tarczycy.

INTRODUCTION: Medullary thyroid carcinomas (MTC) reveal overexpression of several peptide receptors particularly of gastrin and cholecystokinin 2 (CCK2). Experimental studies of various CCK-2/gastrin analogues found that a C-terminal, 8-aminoacid peptide, (D)Glu-octagastrin, has optimal properties. Thus, the aim of our studies was to prepare (99m)Tc-labelled HYNIC-octagastrin, to evaluate its biologic tolerance in animals and introduce for scintigraphy in patients with MTC. MATERIAL AND METHODS: HYNIC-(D)Glu-octagastrin was from piCHEM (Graz, Austria), (99m)Tc generator from Amersham (Health), other reagents were purchased from Sigma. Labelling of the peptide was performed in phosphate buffer of pH 6.0 for 10 minutes at 100(o)C using EDDA and tricine as coligands. RESULTS: The labeling yields were high (above 95%); the specific activity amounted to 1200 to 1430 microCi/microg. Radiochemical purity on SepPak cartridge and ITLC ranged from 94 to 98%. No adverse effects were observed in mice after administration of 10 to 50 times greater doses that those used in patients. Clinical studies comprised 20 patients with MTC and high serum calcitonin. (99m)Tc-EDDA/HYNIC-(D)Glu-octagastrin, 500 to 700 MBq, was administered iv and whole body scintigraphy was performed using a double head gamma-camera (Varicam, Elscint) 2 and 4 hours later. Increased accumulation of the tracer in foci of MTC and its metastases was found in 8 patients. CONCLUSIONS: Scintigraphy with a new gastrin analogue ((D)Glu-octagastrin) makes it possible to detect MTC with overexpression of CCK-2/gastrin receptors and to select patients for receptor-mediated radiopeptide therapy using DOTA-gastrin analogues labelled with (177)Lu and (90)Y.