exenatide and Pancreatic-Neoplasms

Glucagon-like peptide-1 receptor (GLP-1 R) based imaging has shown higher sensitivity for insulinoma localization as compared to other anatomic/functional imaging.. We reviewed the published English literature for GLP-1 R targeted imaging in insulinoma in PubMed until August 2020 in accordance with PRISMA guidelines using the MeSH terms "((Exendin-4 PET/CT) OR (Exendin-4 SPECT/CT) OR (GLP-1 R imaging)) AND (Insulinoma)". An individual patient data-metanalysis (IPD-MA) was performed, and performance parameters were calculated for the histopathological diagnosis of insulinoma.. True-positive (TP), false-positive (FP), false-negative (FN), true-negative (TN), sensitivity (Sn), specificity (Sp), positive predictive value (PPV) and negative predictive value (NPV) for insulinoma localization.. A total of 179 cases (316 lesions) from 16 publications were included for IPD-MA. For insulinoma localization, exendin-4-PET/CT (Sn & PPV: 94%) performed better than exendin-4-SPECT/CT (Sn: 63%, PPV: 94%). The Sn was lower in malignant insulinoma cases whereas the Sp was higher in cases with MEN-1 syndrome. With exendin-4-based imaging, FP uptakes in Brunner's gland, normal pancreas, and other β-cell pathologies and FN results in pancreatic tail lesions and malignancy were seen in a few patients. TN results suggested the correct diagnosis of other endogenous hyperinsulinemic hypoglycaemia (EHH) subtypes.. For insulinoma localization, exendin-4 PET/CT should be preferred over exendin-4 SPECT/CT because of higher sensitivity and specificity. FP uptakes in Brunner's gland, normal pancreas, and other β-cell pathologies and FN results in tail lesions, and malignant insulinomas are limitations. Higher specificity for insulinoma localization is particularly useful in patients with MEN-1 syndrome.

Topics: Diagnostic Imaging; Exenatide; Humans; Insulinoma; Pancreatic Neoplasms; Positron Emission Tomography Computed Tomography

"Glucagonlike peptide-1 (GLP-1) receptor imaging, using radiolabeled exendin-4, was recently established for detecting insulinoma in patients with hyperinsulinemic hypoglycemia. It has proven to be a sensitive and specific method for preoperative localization of insulinoma. This review introduces the development, clinical research, and perspective of GLP-1 receptor imaging mainly in insulinoma.

Topics: Diagnostic Imaging; Exenatide; Glucagon-Like Peptide-1 Receptor; Humans; Insulinoma; Pancreatic Neoplasms

Ectopic insulinomas are extremely rare and challenging to diagnose for clinicians. Precise preoperative localization is essential to successful treatment.. A 23-year-old man presented with a 1-year history of recurrent hypoglycemia.. Examinations in the local hospital did not reveal any pancreatic lesion. After admission, a fasting test and a 5-hour oral glucose tolerance test (OGTT) suggested a diagnosis of endogenous hyperinsulinemic hypoglycemia. Enhanced volume perfusion computed tomography (VPCT) revealed 2 nodules in the tail of the pancreas, a nodule in the gastric antrum, and a nodule in the hilum of the spleen. To differentiate which nodule was responsible for hypoglycemia, we performed 68Ga-Exendin-4 PET/CT and 68Ga-DOTATATE PET/CT which helped to make a conclusive diagnosis that the lesion in the gastric antrum was an ectopic insulinoma.. The patient was cured with minimally invasive laparoscopic resection of the tumor.. The symptoms were relieved and the blood glucose level remained normal after surgery.. This case shows that 68Gallium-exendin-4 PET/CT is useful for precise localization and thereby successful treatment of insulinoma, especially for occult insulinomas and those derived from an ectopic pancreas.

Topics: Choristoma; Exenatide; Gallium Radioisotopes; Glucose Tolerance Test; Humans; Hypoglycemia; Insulinoma; Male; Organometallic Compounds; Pancreas; Pancreatic Neoplasms; Positron Emission Tomography Computed Tomography; Pyloric Antrum; Radiopharmaceuticals; Recurrence; Stomach Neoplasms; Young Adult

Glucagon-like peptide 1 (GLP-1) receptors expression has been found on many types of cancer cells. In case of benign insulinoma the density of those receptors is even higher than the density of somatostatin receptors. This article presents the results of clinical trials proving the utility of GLP-1 receptors imaging. Scintigraphy or positron emission tomography with the use of GLP-1 analogues labelled with appropriate radioisotopes (111In, 99mTc, 68Ga, 18F or 64Cu) seem to be superior compared with other available techniques in diagnosis of hardly detectable benign insulinoma. While surgery is the only effective therapy for insulinoma patients, therefore proper preoperative localization of the tumor allows sparing operation. Glucagon-like peptide 1 receptors might become also a target for imaging of other tumors such as gastrinoma, pheochromocytoma and medullary thyroid cancer (MTC), which also were shown to overexpress this type of receptors. However, studies with larger groups of patients are required to prove the clinical usefulness of this indication. Moreover GLP-1 receptor imaging seems to be a potential tool to evaluate pancreatic beta cell mass (BCM). It may be useful in the early diagnosis of beta cell loss in preclinical phases of diabetes. The panceratic beta cells imaging may influence the prophylaxis of diabetes and management of diabetic patients. Presented results of clinical trials prove that glucagon-like peptide 1 receptor imaging might become helpful diagnostic strategy particularly in case of patients with benign insulinoma tumors, but also patients with gastrinoma, pheochromocytoma, medullary thyroid cancer and diabetes.

Topics: Biomarkers, Tumor; Exenatide; Forecasting; Glucagon-Like Peptide 1; Humans; Isotope Labeling; Molecular Imaging; Pancreatic Neoplasms; Peptides; Radionuclide Imaging; Radiopharmaceuticals; Venoms

Recent suggestions that glucagon-like peptide-1 (GLP-1)-based therapies could cause pancreatitis, and even pancreatic cancer, are based on:. The worrying histological changes are not reproduced in all studies and are unexpectedly variable with different GLP-1-based therapies.. Singh's findings that pancreatitis is doubled with GLP-1-based therapies could relate to their use in obese patients who are prone to pancreatitis risk factors--gallstones and hypertriglyceridaemia. The other observational studies do not find an association between GLP-1-based therapies and pancreatitis.. The increased reports of pancreatitis and pancreatic cancer are likely to be attributable to 'notoriety bias'.. Butler's findings for those on GLP-1-based therapies vs. those not, could have other explanations. Meanwhile: META ANALYSIS: Randomized control trials with GLP-1-based therapies do not find increased pancreatitis risk. Meta-analysis of 53 randomized controlled trials including 20 212 dipeptidyl peptidase-4 inhibitor-treated patients found a significantly reduced risk of major adverse cardiovascular events [odds ratio 0.689 (0.528-0.899), P = 0.006] for dipeptidyl peptidase-4 inhibitors compared with control subjects.. The evidence suggests that there is more than a possibility that some of the GLP-1 receptor agonists, and possibly also some dipeptidyl peptidase-4 inhibitors, may be associated with reduced cardiovascular events. Eight ongoing long-term cardiovascular randomized controlled trials will report from September 2013 onwards. These trials should resolve the issue of pancreatitis risk and substantiate the extent of benefit.. Whilst we should remain vigilant, currently the balance of evidence is strongly in support of GLP-1-based therapy, with benefits far outweighing potential risks.

Topics: Adverse Drug Reaction Reporting Systems; Cardiovascular Diseases; Diabetes Mellitus, Type 2; Diabetic Angiopathies; Dipeptidyl-Peptidase IV Inhibitors; Exenatide; Female; Glucagon-Like Peptide 1; Glucagon-Like Peptide-1 Receptor; Humans; Incretins; Liraglutide; Male; Pancreatic Neoplasms; Pancreatitis; Patient Selection; Peptides; Randomized Controlled Trials as Topic; Receptors, Glucagon; Risk Assessment; Risk Factors; Venoms

Topics: Adenocarcinoma; Antiemetics; Antineoplastic Combined Chemotherapy Protocols; Combined Modality Therapy; Dexamethasone; Diabetes Mellitus, Type 2; Disease Management; Drug Resistance; Drug Therapy, Combination; Exenatide; Fluorouracil; Humans; Hyperglycemia; Hyperglycemic Hyperosmolar Nonketotic Coma; Hypoglycemic Agents; Insulin; Leucovorin; Male; Malnutrition; Metformin; Middle Aged; Nausea; Organoplatinum Compounds; Oxaliplatin; Palliative Care; Pancreatectomy; Pancreatic Neoplasms; Peptides; Sulfonylurea Compounds; Venoms

Preoperative localization of insulinoma is a clinical dilemma. We aimed to investigate whether glucagon-like peptide-1 receptor (GLP-1R) PET/CT with (68)Ga-NOTA-MAL-cys(40)-exendin-4 ((68)Ga-NOTA-exendin-4) is efficient in detecting insulinoma.. In our prospective cohort study, patients with endogenous hyperinsulinemic hypoglycemia were enrolled. CT, MRI, endoscopic ultrasound, and (99m)Tc-hydrazinonicotinamide-TOC SPECT/CT were done according to standard protocols. GLP-1R PET/CT was performed 30-60 min after the injection of (68)Ga-NOTA-exendin-4. The gold standard for diagnosis was the histopathologic results after surgery.. Of 52 recruited patients, 43 patients with histopathologically proven insulinomas were included for the imaging studies. Nine patients did not undergo surgical intervention. (68)Ga-NOTA-exendin-4 PET/CT correctly detected insulinomas in 42 of 43 patients with high tumor uptake (mean SUVavg ± SD, 10.2 ± 4.9; mean SUVmax ± SD, 23.6 ± 11.7), resulting in sensitivity of 97.7%. In contrast, (99m)Tc-hydrazinonicotinamide-TOC SPECT/CT showed a low sensitivity of 19.5% (8/41) in this group of patients; however, it successfully localized the tumor that was false-negative with GLP-1R PET/CT. The sensitivities of CT, MR, and endoscopic ultrasonography were 74.4% (32/43), 56.0% (14/25), and 84.0% (21/25), respectively.. (68)Ga-NOTA-exendin-4 PET/CT is a highly sensitive imaging technique for the localization of insulinoma.

Topics: Adolescent; Adult; Aged; Child; Cohort Studies; Exenatide; Female; Gallium Radioisotopes; Glucagon-Like Peptide-1 Receptor; Heterocyclic Compounds; Heterocyclic Compounds, 1-Ring; Humans; Insulinoma; Male; Middle Aged; Pancreatic Neoplasms; Peptides; Positron Emission Tomography Computed Tomography; Prospective Studies; Venoms; Young Adult

Small benign insulinomas are hard to localise, leading to difficulties in planning of surgical interventions. We aimed to prospectively assess the insulinoma detection rate of single-photon emission CT in combination with CT (SPECT/CT) with a glucagon-like peptide-1 receptor avid radiotracer, and compare detection rates with conventional CT/MRI techniques.. In our prospective imaging study, we enrolled adults aged 25-81 years at centres in Germany, Switzerland, and the UK. Eligible patients had proven clinical and biochemical endogenous hyperinsulinaemic hypoglycaemia and no evidence for metastatic disease on conventional imaging. CT/MRI imaging was done at referring centres according to standard protocols. At three tertiary nuclear medicine centres, we used whole body planar images and SPECT/CT of the abdomen up to 168 h after injection of (111)In-[Lys40(Ahx-DTPA-(111)In)NH2]-exendin-4 ((111)In-DTPA-exendin-4) to identify insulinomas. Consenting patients underwent surgery and imaging findings were confirmed histologically.. Between Oct 1, 2008, and Dec 31, 2011, we recruited 30 patients. All patients underwent (111)In-DTPA-exendin-4 imaging, 25 patients underwent surgery (with histological analysis), and 27 patients were assessed with CT/MRI. (111)In-DTPA-exendin-4 SPECT/CT correctly detected 19 insulinomas and four additional positive lesions (two islet-cell hyperplasia and two uncharacterised lesions) resulting in a positive predictive value of 83% (95% CI 62-94). One true negative (islet-cell hyperplasia) and one false negative (malignant insulinoma) result was identified in separate patients by (111)In-DTPA-exendin-4 SPECT/CT. Seven patients (23%) were referred to surgery on the basis of (111)In-DTPA-exendin-4 imaging alone. For 23 assessable patients, (111)In-DTPA-exendin-4 SPECT/CT had a higher sensitivity (95% [95% CI 74-100]) than did CT/MRI (47% [27-68]; p=0.011).. (111)In-DTPA-exendin-4 SPECT/CT could provide a good second-line imaging strategy for patients with negative results on initial imaging with CT/MRI.. Oncosuisse, the Swiss National Science Foundation, and UK Department of Health.

Topics: Adult; Aged; Aged, 80 and over; Exenatide; Female; Glucagon-Like Peptide-1 Receptor; Humans; Indium Radioisotopes; Insulinoma; Magnetic Resonance Imaging; Male; Middle Aged; Pancreatic Neoplasms; Pentetic Acid; Peptides; Receptors, Glucagon; Tomography, Emission-Computed; Tomography, Emission-Computed, Single-Photon; Venoms

Exendin, an analogue of the glucagon-like peptide 1 (GLP1), is an excellent tracer for molecular imaging of pancreatic beta cells and beta cell-derived tumours. The commonly used form, exendin-4, activates the GLP1 receptor and causes internalisation of the peptide-receptor complex. As a consequence, injection of exendin-4 can lead to adverse effects such as nausea, vomiting and hypoglycaemia and thus requires close monitoring during application. By comparison, the antagonist exendin(9-39) does not activate the receptor, but its lack of internalisation has precluded its use as a tracer. Improving the cellular uptake of exendin(9-39) could turn it into a useful alternative tracer with less side-effects than exendin-4.. We conjugated exendin-4 and exendin(9-39) to the well-known cell-penetrating peptide (CPP) penetratin. We evaluated cell binding and internalisation of the radiolabelled peptides in vitro and their biodistribution in vivo.. Exendin-4 showed internalisation irrespective of the presence of the CPP, whereas for exendin(9-39) only the penetratin conjugate internalised. Conjugation to the CPP also enhanced the in vivo tumour uptake and retention of exendin(9-39).. We demonstrate that penetratin robustly improves internalisation and tumour retention of exendin(9-39), opening new avenues for antagonist-based in vivo imaging of GLP1R.

Topics: Cell-Penetrating Peptides; Exenatide; Glucagon-Like Peptide-1 Receptor; Humans; Insulinoma; Pancreatic Neoplasms; Tissue Distribution; Venoms

There are increasing data on the potential risk of pancreatic carcinoma associated with glucagon-like peptide 1 receptor agonists (GLP-1RAs).. The study aimed to determine whether GLP-1RAs are associated with increased detection of pancreatic carcinoma based on the FDA Adverse Events Reporting System and clarify its potential mechanisms through keyword co-occurrence analysis from literature database.. Disproportionality and Bayesian analyses were used for signal detection using reporting odds ratio (ROR), proportional reporting ratio (PRR), information component (IC), and empirical Bayesian geometric mean (EBGM). Mortality, life-threatening events, and hospitalizations were also investigated. VOSviewer was adopted to generate visual analysis of keyword hotspots.. A total of 3073 pancreatic carcinoma cases were related to GLP-1RAs. Five GLP-1RAs were detected with signals for pancreatic carcinoma. Liraglutide had the strongest signal detection (ROR 54.45, 95% CI 51.21-57.90; PRR 52.52, 95% CI 49.49-55.73; IC 5.59; EBGM 48.30). The signals of exenatide (ROR 37.32, 95% CI 35.47-39.28; PRR 36.45, 95% CI 34.67-38.32; IC 5.00; EBGM 32.10) and lixisenatide (ROR 37.07, 95% CI 9.09-151.09; PRR 36.09; 95% CI 9.20-141.64; IC 5.17, EBGM 36.09) were stronger than those of semaglutide (ROR 7.43, 95% CI 5.22-10.57; PRR 7.39; 95% CI 5.20-10.50; IC 2.88, EBGM 7.38) and dulaglutide (ROR 6.47, 95% CI 5.56-7.54; PRR 6.45; 95% CI 5.54-7.51; IC 2.67, EBGM 6.38). The highest mortality rate occurred in exenatide (63.6%). Based on the bibliometric investigation, cAMP/protein-kinase, Ca. Based on this pharmacovigilance study, GLP-1RAs, except albiglutide, are associated with pancreatic carcinoma.

Topics: Bayes Theorem; Diabetes Mellitus, Type 2; Exenatide; Glucagon-Like Peptide 1; Glucagon-Like Peptide-1 Receptor; Humans; Hypoglycemic Agents; Pancreatic Neoplasms; Pharmacovigilance

A 55-year-old woman with endogenous hyperinsulinemia hypoglycemia was clinically diagnosed with insulinoma. Contrast-enhanced MRI revealed an inconclusive hypointense lesion in the pancreatic tail, and the enhancement pattern does not support the diagnosis of insulinoma. 68Ga-DOTATATE PET/CT showed intense radioactivity in this nodule, similar to the radioactivity of the adjacent spleen. Therefore, the diagnosis of accessory spleen cannot be excluded. Follow-up with 68Ga-exendin-4 PET/CT also showed intense uptake in this nodule, but no significant uptake in the spleen was observed at this time. Therefore, the insulinoma was unmasked from the spleen, excluding the diagnosis of accessory spleen, and allowing curative surgery.

Topics: Exenatide; Female; Humans; Insulinoma; Magnetic Resonance Imaging; Middle Aged; Organometallic Compounds; Pancreatic Neoplasms; Positron Emission Tomography Computed Tomography; Positron-Emission Tomography; Radionuclide Imaging; Spleen

Unmet clinical needs for the management of insulinoma include a low proportion of patients having surgical treatment, postoperative diabetes mellitus, and residual hypoglycemia. Glucagon-like peptide-1 (GLP-1) receptor-targeted imaging such as that using [

Topics: Exenatide; Glucagon-Like Peptide-1 Receptor; Humans; Insulinoma; Japan; Pancreatic Neoplasms; Positron-Emission Tomography

Insulinomas are neuroendocrine tumors that are mainly found in the pancreas. Surgical resection is currently the first-line treatment for insulinomas; thus, it is vital to preoperatively determine their locations. The marked expression of the glucagon-like peptide-1 receptor (GLP-1R) is seen in pancreatic β-cells and almost all insulinomas. Radiolabeled derivatives of exendin-4, a GLP-1R agonist, have been used with nuclear medicine imaging techniques for the

Topics: Albumins; Animals; Exenatide; Glucagon-Like Peptide-1 Receptor; Insulinoma; Kidney; Mice; Pancreatic Neoplasms; Tissue Distribution; Tomography, Emission-Computed, Single-Photon

Insulinomas are neuroendocrine tumors that are derived from pancreatic β-cells, and they often overexpress the glucagon-like peptide-1 receptor (GLP-1R). Radiolabeled exendin-4 derivatives have been used to noninvasively detect the GLP-1R during the diagnosis and preoperative localization of insulinomas; however, their marked renal accumulation can hinder the imaging of pancreatic tail lesions. In this study, we designed and synthesized

Topics: Albumins; Animals; Exenatide; Glucagon-Like Peptide-1 Receptor; Humans; Indium; Insulinoma; Mice; Pancreatic Neoplasms; Peptides; Structure-Activity Relationship; Tissue Distribution; Tomography, Emission-Computed, Single-Photon

Targeting of glucagon-like peptide 1 receptor (GLP-1R), expressed on the surface of pancreatic β-cells, is of great interest for the development of advanced therapies for diabetes and diagnostics for insulinoma. We report the conjugation of exendin-4 (Ex-4), an approved drug to treat type 2 diabetes, to poly-γ-glutamic acid (γ-PGA) to obtain more stable and effective GLP-1R ligands. Exendin-4 modified at Lysine-27 with PEG4-maleimide was conjugated to γ-PGA functionalized with furan, in different molar ratios, exploiting a chemoselective Diels-Alder cycloaddition. The γ-PGA presenting the highest number of conjugated Ex-4 molecules (average 120 per polymeric chain) showed a double affinity towards GLP-1R with respect to exendin per se, paving the way to improved therapeutic and diagnostic applications.

Topics: Diabetes Mellitus, Type 2; Exenatide; Glucagon-Like Peptide-1 Receptor; Glutamic Acid; Humans; Pancreatic Neoplasms; Peptides; Polyglutamic Acid; Radiopharmaceuticals

Because management is very different, it is important to differentiate between small focal insulinomas and diffuse pancreatic dysplasia (nesidioblastosis) in patients with confirmed endogenous hyperinsulinaemic hypoglycaemia (EHH). Most insulinomas highly express glucagon-like peptide-1 receptors enabling positron emission tomography-computed tomography imaging with its radiolabelled analogue;. To determine: (i) the utility of Exendin in EHH patients in a clinical setting; and (ii) whether the degree of Exendin uptake differentiates non-insulinoma pancreatogenous hypoglycaemia syndrome (NIPHS) from post-gastric bypass hypoglycaemia (PGBH).. This retrospective study reviewed the clinical, biochemistry and prior imaging findings in confirmed EHH patients referred for Exendin. Accuracy of Exendin was based on surgical findings and treatment outcomes. Finally, average Exendin uptake (SUVmax) of five PGBH studies was compared with the SUVmax of a key NIPHS case report.. Twenty of 25 consecutive patients had confirmed EHH. Exendin located insulinomas in eight of nine patients enabling successful surgical excision with rapid and durable cure. Exendin correctly identified diffuse nesidioblastosis in two of three cases requiring partial pancreatectomy for hypoglycaemia control. All three relapsed within 1.7 years with one needing completion pancreatectomy. Establishing the cause in the remainder relied on other investigations, clinical correlation and response to empirical treatment. Finally, Exendin SUVmax could not distinguish between NIPHS and PGBH.. In EHH patients, Exendin accurately identifies the site of insulinoma and thereby differentiates it from nesidioblastosis but negative findings should not be ignored. Exendin is unlikely to differentiate between normal pancreatic uptake, NIPHS and PGBH.

Topics: Exenatide; Humans; Hypoglycemia; Insulinoma; Nesidioblastosis; Pancreatic Neoplasms; Positron Emission Tomography Computed Tomography; Retrospective Studies

Topics: Albumins; Animals; Biological Availability; Cell Line; Cricetinae; Drug Delivery Systems; Exenatide; Female; Glucagon-Like Peptide-1 Receptor; Humans; Indium Radioisotopes; Inhibitory Concentration 50; Insulinoma; Kidney; Mice; Mice, Nude; Pancreatic Neoplasms; Peptides; Protein Binding; Radiopharmaceuticals; Tissue Distribution; Tomography, Emission-Computed, Single-Photon; Transfection

A retrospective cohort study, supplemented with a nested case-control study, was performed using two administrative databases from commercial health plans in the United States to compare the incidence of pancreatic and thyroid cancer among users of exenatide versus other antidiabetic drugs (OADs). Patients with type 2 diabetes who initiated exenatide or OADs between 1 June 2005 and 30 June 2015 were included. Pancreatic and thyroid cancers were identified using chart-validated algorithms in the cohort study. Cases in the nested case-control study were chart-confirmed pancreatic or thyroid cancers, and controls were sampled using risk-set sampling. The time-fixed analyses comparing 33 629 exenatide initiators with 49 317 propensity-score-matched OAD initiators yielded hazard ratios of 0.76 (95% confidence interval [CI] 0.47-1.21) for pancreatic cancer and 1.46 (95% CI 0.98-2.19) for thyroid cancer. Results in the time-dependent analyses by cumulative duration or dose were similar. Nested case-control analyses yielded rate ratios of 0.61 (95%CI, 0.37-1.00) for pancreatic cancer and 0.89 (95% CI, 0.64-1.24) for thyroid cancer. This observational study suggested exenatide use was not associated with an increased risk of pancreatic or thyroid cancer.

Topics: Adult; Aged; Cohort Studies; Databases, Factual; Diabetes Mellitus, Type 2; Exenatide; Female; Humans; Hypoglycemic Agents; Incidence; Incretins; Male; Middle Aged; Pancreatic Neoplasms; Propensity Score; Proportional Hazards Models; Retrospective Studies; Thyroid Neoplasms; United States

GLP-1 receptors are ideal targets for preoperative imaging of benign insulinoma and for quantifying the beta cell mass. The existing clinical tracers targeting GLP-1R are all agonists with low specific activity and very high kidney uptake. In order to solve those issues we evaluated GLP-1R agonist Ex-4 and antagonist Ex(9-39) radioiodinated at Tyr40 side by side with [Nle14,Lys40(Ahx-DOTA-68Ga)NH2]Ex-4 (68Ga-Ex-4) used in the clinic. The Kd, Bmax, internalization and binding kinetics of [Nle14,125I-Tyr40-NH2]Ex-4 and [Nle14,125I-Tyr40-NH2]Ex(9-39) were studied in vitro using Ins-1E cells. Biodistribution and imaging studies were performed in nude mice bearing Ins-1E xenografts. In vitro evaluation demonstrated high affinity binding of the [Nle14,125I-Tyr40-NH2]Ex-4 agonist to the Ins-1E cells with fast internalization kinetics reaching a plateau after 30 min. The antagonist [Nle14,125I-Tyr40-NH2]Ex(9-39) did not internalize and had a 4-fold higher Kd value compared to the agonist. In contrast to [Nle14,125I-Tyr40-NH2]Ex(9-39), which showed low and transient tumor uptake, [Nle14,125I-Tyr40-NH2]Ex-4 demonstrated excellent in vivo binding properties with tumor uptake identical to that of 68Ga-Ex-4, but substantially lower kidney uptake resulting in a tumor-to-kidney ratio of 9.7 at 1 h compared to 0.3 with 68Ga-Ex-4. Accumulation of activity in thyroid and stomach for both peptides, which was effectively blocked by irenat, confirms that in vivo deiodination is the mechanism behind the low kidney retention of iodinated peptides. The 124I congener of [Nle14,125I-Tyr40-NH2]Ex-4 demonstrated a similar favourable biodistribution profile in the PET imaging studies in contrast to the typical biodistribution pattern of [Nle14,Lys40(Ahx-DOTA-68Ga)NH2]Ex-4. Our results demonstrate that iodinated Ex-4 is a very promising tracer for imaging of benign insulinomas. It solves the problem of high kidney uptake of the radiometal-labelled tracers by improving the tumor-to-kidney ratio measured for [Nle14,Lys40(Ahx-DOTA-68Ga)NH2]Ex-4 by 32 fold.

Topics: Animals; Cell Line, Tumor; Exenatide; Female; Gallium Radioisotopes; Glucagon-Like Peptide-1 Receptor; Heterografts; Humans; Insulinoma; Iodine Radioisotopes; Kidney; Mice; Mice, Inbred BALB C; Mice, Nude; Pancreatic Neoplasms; Peptides; Positron Emission Tomography Computed Tomography; Radiopharmaceuticals; Tissue Distribution; Venoms

Topics: Exenatide; Female; Gallium Radioisotopes; Heterocyclic Compounds, 1-Ring; Humans; Hyperinsulinism; Hypoglycemia; Insulinoma; Middle Aged; Pancreas; Pancreatic Neoplasms; Pancreaticojejunostomy; Peptides; Positron Emission Tomography Computed Tomography; Treatment Outcome; Venoms

A 61-year-old woman with biochemically proven endogenous hyperinsulinemic hypoglycemia and negative conventional imaging underwent 68Ga-NOTA-exendin-4 PET/CT for localization of insulinoma. Focal intense radioactivity in the tail of the pancreas was observed that was subsequently confirmed as insulinoma pathologically after surgical resection. In addition, esophageal carcinoma with lymph node and hepatic metastases was found by FDG PET/CT in the same patient. Neither the primary carcinoma nor the metastases showed increased radioactivity on 68Ga-NOTA-exendin-4 PET/CT.

Topics: Carcinoma; Coordination Complexes; Esophageal Neoplasms; Exenatide; Female; Heterocyclic Compounds; Heterocyclic Compounds, 1-Ring; Humans; Insulinoma; Liver Neoplasms; Middle Aged; Multimodal Imaging; Pancreatic Neoplasms; Peptides; Positron-Emission Tomography; Radiopharmaceuticals; Tomography, X-Ray Computed; Venoms

Incretin-based therapies have been associated with an increased risk of pancreatitis. Recently, various histological abnormalities have been reported in human pancreatic tissue from brain-dead organ donors who had been exposed to incretin-based drugs. In the present study we examined pancreatic tissue collected at surgery.. Human pancreatic tissue from 7 type 2-diabetic patients treated with incretin-based drugs (type 2-I), 6 diabetic patients without incretin treatment (type 2-NI), 11 patients without diabetes (no diabetes group) and 9 brain-dead organ donors (BDOD group) was examined.. Fractional beta-cell area was reduced in the type 2-NI group compared to the group without diabetes (P < .05), but there was no difference compared to the type 2-I patients. Alpha-cell area (P = .30), beta-cell replication (P = .17) and alpha-cell replication (P = .91) were not different. There were also no differences in acinar cell (P = .13) and duct cell replication (P = .099). Insulin-positive duct cells were more frequent in the type 2-I and the BDOD groups (P = .034). No co-expression of insulin and glucagon was detected. Pancreatic intraepithelial neoplasia (PanIN) lesions were very rare, all low-grade (PanIN 1a and 1b) and tended to occur more frequently in the type 2-I group (P = .084).. The present results did not reveal marked histological abnormalities in the pancreas of incretin-treated patients with type 2 diabetes. Low numbers of specimens available and a large inter-individual variability of the findings warrant caution regarding the interpretation of histological data concerning drug effects on the human pancreas.

Topics: Acinar Cells; Adamantane; Adenocarcinoma; Adult; Aged; Carcinoma in Situ; Case-Control Studies; Cystadenoma; Diabetes Mellitus, Type 2; Digestive System Surgical Procedures; Dipeptides; Exenatide; Female; Glucagon; Glucagon-Secreting Cells; Humans; Incretins; Insulin; Insulin-Secreting Cells; Islets of Langerhans; Male; Middle Aged; Neuroendocrine Tumors; Nitriles; Organ Size; Pancreas; Pancreas, Exocrine; Pancreatic Neoplasms; Pancreatitis, Chronic; Peptides; Pyrrolidines; Sitagliptin Phosphate; Tissue Donors; Venoms; Vildagliptin

Topics: Exenatide; Gallium Radioisotopes; Heterocyclic Compounds; Heterocyclic Compounds, 1-Ring; Humans; Insulinoma; Male; Middle Aged; Multimodal Imaging; Neoplasms, Unknown Primary; Pancreatic Neoplasms; Peptides; Positron-Emission Tomography; Radiopharmaceuticals; Tomography, X-Ray Computed; Venoms

Peptides display many characteristics of efficient imaging agents such as rapid targeting, fast background clearance, and low non-specific cellular uptake. However, poor stability, low affinity, and loss of binding after labeling often preclude their use in vivo. Using glucagon-like peptide-1 receptor (GLP-1R) ligands exendin and GLP-1 as a model system, we designed a novel α-helix-stabilizing linker to simultaneously address these limitations. The stabilized and labeled peptides showed an increase in helicity, improved protease resistance, negligible loss or an improvement in binding affinity, and excellent in vivo targeting. The ease of incorporating azidohomoalanine in peptides and efficient reaction with the dialkyne linker enable this technique to potentially be used as a general method for labeling α helices. This strategy should be useful for imaging beta cells in diabetes research and in developing and testing other peptide targeting agents.

Topics: Amino Acid Sequence; Animals; Exenatide; Glucagon-Like Peptide 1; Glucagon-Like Peptide-1 Receptor; Histological Techniques; Insulin-Secreting Cells; Ligands; Mice; Mice, Inbred C57BL; Microscopy; Models, Molecular; Molecular Sequence Data; Optical Imaging; Pancreatic Neoplasms; Peptides; Protein Stability; Protein Structure, Secondary; Receptors, Glucagon; Venoms

High expression of glucagon-like peptide-1 receptor (GLP-1R) in insulinoma supplies a potential drug target for tumor imaging. Exendin-4 can specifically bind to GLP-1R as an agonist and its analogs are extensively used in receptor imaging studies.. A new GLP-1R imaging agent, [(18)F]AlF-NOTA-MAL-Cys(39)-exendin-4, was designed and prepared for insulinoma imaging.. Cys(39)-exendin-4 was conjugated with NOTA-MAL, then the compound was radiolabeled with [(18)F]AlF complex to obtained [(18)F]AlF-NOTA-MAL-Cys(39)-exendin-4. The tumor-targeting characters of the tracer were evaluated in INS-1 cells and BALB/c nude mice models.. [(18)F]AlF-NOTA-MAL-Cys(39)-exendin-4 can be efficiently produced with a yield of 17.5 ± 3.2% (non-decay corrected) and radiochemical purity of >95%. The IC50 value of displacement [(18)F]AlF-NOTA-MAL-Cys(39)-exendin-4 with Cys(39)-exendin-4 was 13.52 ± 1.36 nM. PET images showed excellent tumor visualization with high uptake (9.15 ± 1.6%ID/g at 30 min and 7.74 ± 0.87%ID/g at 60 min). The tumor to muscle, pancreas and liver ratios were 63.25, 3.85 and 7.29 at 60 min after injection. GLP-1R binding specificity was demonstrated by co-injection with an excess of unlabeled Cys(39)-exendin-4 and the tumor uptake was found to be reduced significantly.. [(18)F]AlF-NOTA-MAL-Cys(39)-exendin-4 shows favorable characteristics for insulinoma imaging and may be translated to clinical studies.

Topics: Animals; Cell Line, Tumor; Cysteine; Drug Stability; Exenatide; Female; Fluorine Radioisotopes; Heterocyclic Compounds; Heterocyclic Compounds, 1-Ring; Insulinoma; Maleimides; Mice; Mice, Nude; Pancreatic Neoplasms; Peptides; Positron-Emission Tomography; Rats; Venoms

Beta cell death caused by endoplasmic reticulum (ER) stress is a key factor aggravating type 2 diabetes. Exenatide, a glucagon-like peptide (GLP)-1 receptor agonist, prevents beta cell death induced by thapsigargin, a selective inhibitor of ER calcium storage. Here, we report on our proteomic studies designed to elucidate the underlying mechanisms. We conducted comparative proteomic analyses of cellular protein profiles during thapsigargin-induced cell death in the absence and presence of exenatide in INS-1 rat insulinoma cells. Thapsigargin altered cellular proteins involved in metabolic processes and protein folding, whose alterations were variably modified by exenatide treatment. We categorized the proteins with thapsigargin initiated alterations into three groups: those whose alterations were 1) reversed by exenatide, 2) exaggerated by exenatide, and 3) unchanged by exenatide. The most significant effect of thapsigargin on INS-1 cells relevant to their apoptosis was the appearance of newly modified spots of heat shock proteins, thimet oligopeptidase and 14-3-3β, ε, and θ, and the prevention of their appearance by exenatide, suggesting that these proteins play major roles. We also found that various modifications in 14-3-3 isoforms, which precede their appearance and promote INS-1 cell death. This study provides insights into the mechanisms in ER stress-caused INS-1 cell death and its prevention by exenatide.

Topics: 14-3-3 Proteins; Animals; Cell Death; Cell Line; Endoplasmic Reticulum Stress; Exenatide; Glucagon-Like Peptide-1 Receptor; Insulinoma; Pancreatic Neoplasms; Peptides; Phosphorylation; Protein Interaction Maps; Protein Processing, Post-Translational; Proteome; Proteomics; Rats; Thapsigargin; Venoms

Clinical studies have demonstrated the potential of radiometallated exendin-4 derivatives for the imaging of glucagonlike peptide-1 receptor-overexpressing insulinomas. Recently investigated exendin-4 derivatives were radiolabeled with the SPECT isotopes 99mTc or 111In. Despite promising results, the low spatial resolution associated with SPECT and the occasional need to perform imaging several days after injection for the demarcation of insulinomas from the kidneys represent current limitations. The aim of this work was the development of exendin-4 derivatives for the imaging of insulinomas by high-resolution PET at early or late time points after injection of the radiotracer.. An exendin-4 derivative conjugated to desferrioxamine (DFO) was used for radiolabeling with the PET isotopes 68Ga and 89Zr. Both radiotracers were evaluated in vitro with RIN-m5F cells for their cell internalization properties as well as affinities and specificities toward the glucagonlike peptide-1 receptor. Serum stabilities of the radiopeptides were assessed in blood serum, and their distribution coefficient was determined by the shake-flask method. Biodistribution experiments were performed with nude mice bearing RIN-m5F xenografts. For all experiments, clinically evaluated [Lys40-(AHX-DTPA-111In)NH2]exendin-4 was used as a reference compound.. [Lys40-(AHX-DFO)NH2]exendin-4 was labeled with 89Zr and 68Ga in high radiochemical yield and purity. In vitro experiments showed favorable cell uptake and receptor affinity for [Lys40-(AHX-DFO-68Ga)NH2]exendin-4, and [Lys40-(AHX-DFO-89Zr)NH2]exendin-4 and [Lys40-(AHX-DTPA-111In)NH2]exendin-4 performed similarly well. In biodistribution experiments, [Lys40-(AHX-DFO-68Ga)NH2]exendin-4 exhibited a significantly enhanced tumor uptake 1 h after injection in comparison to the other 2 radiotracers. Tumor uptake of [Lys40-(AHX-DFO-89Zr)NH2]exendin-4 was comparable to that of [Lys40-(AHX-DTPA-111In)NH2]exendin-4 at 1-48 h after injection. All compounds showed a fast blood clearance and low accumulation in receptor-negative organs and tissue with the exception of the kidneys, a known characteristic for exendin-4-based radiotracers.. 68Ga- and 89Zr-radiolabeled [Lys40-(AHX-DFO)NH2]exendin-4 exhibit characteristics comparable or superior to the clinically tested reference compound [Lys40-(AHX-DTPA-111In)NH2]exendin-4 and, thus, represent potential new tracers for the imaging of insulinomas by PET.

Topics: Animals; Deferoxamine; Exenatide; Gallium Radioisotopes; Insulinoma; Isotope Labeling; Mice; Mice, Nude; Pancreatic Neoplasms; Peptides; Positron-Emission Tomography; Radioisotopes; Radiopharmaceuticals; Tissue Distribution; Venoms; Zirconium

Exendin-4 (Ex-4) is an anti-diabetic drug that is a potent agonist of the glucagon-like peptide-1 (GLP-1) receptor. It has already been approved for the treatment of type 2 diabetes mellitus, but its underlying mechanisms of action are not fully understood. Calcium/calmodulin-dependent serine protein kinase (CASK), which plays a vital role in the transport and release of neurotransmitters in neurons, is expressed in pancreatic islet cells and β-cells. This study aimed to investigate whether CASK is involved in the insulin secretagogue action induced by Ex-4 in INS-1 cells.. A glucose-stimulated insulin secretion (GSIS) assay was performed with or without siRNA treatment against CASK. The expression level and location of CASK were evaluated by real-time PCR, western blotting and immunofluorescence. With the use of a protein kinase A (PKA) inhibitor or an exchange protein directly activated by cAMP-2 (Epac2) agonist, immunoblotting was performed to establish the signaling pathway through which Ex-4 alters CASK expression.. Knock-down of CASK significantly attenuated the Ex-4-enhanced insulin release, and we showed that Ex-4 could increase transcription of CASK mRNA and expression of CASK protein but did not change the cellular location of CASK. A PKA inhibitor reduced the ability of Ex-4 to stimulate CASK expression, but an Epac2 agonist had no effect suggesting that regulation was mediated by the cAMP/PKA pathway.. Our study suggests that the stimulation of β-cell insulin secretion by Ex-4 is mediated, at least in part, by CASK via a novel signaling mechanism.

Topics: Animals; Blotting, Western; Cell Line, Tumor; Cyclic AMP-Dependent Protein Kinases; Diabetes Mellitus, Type 2; Exenatide; Gene Knockdown Techniques; Glucagon-Like Peptide 1; Guanylate Kinases; Hypoglycemic Agents; Insulin; Insulin Secretion; Insulinoma; Microscopy, Fluorescence; Pancreatic Neoplasms; Peptides; Rats; Real-Time Polymerase Chain Reaction; RNA, Small Interfering; Signal Transduction; Venoms

Glucagon-like peptide-1 receptor (GLP-1R) is a specific target for insulinomas imaging since it is overexpressed in the tumor. Exendin-4 exhibits high affinity for the GLP-1R. In this study, a novel (18)F-labeled exendin-4 analog, (18)F-FBEM-Cys(39)-exendin-4, was synthesized and its potentials for GLP-1R imaging were also evaluated.. (18)F-FBEM was synthesized by coupling (18)F-fluorobenzoic acid ((18)F-FBA) with N-(2-aminoethyl) maleimide, and the reaction conditions were optimized. Cys(39)-exendin-4 was then conjugated with (18)F-FBEM to obtain (18)F-FBEM-Cys(39)-exendin-4. The GLP-1R targeting potential and pharmacokinetic profile of the tracer were analyzed in INS-1 insulinoma and MDA-MB-435 breast tumor model, respectively.. Under the optimal conditions, the yield of radiolabeled (18)F-FBEM was 49.1 ± 2.0 % (based on (18)F-FBA, non-decay corrected). The yield of (18)F-FBEM-Cys(39)-exendin-4 was 35.1 ± 2.6 % (based on the starting (18)F-FBEM, non-decay corrected). The radiochemical purity of (18)F-FBEM-Cys(39)-exendin-4 is >95 %, and the specific activity was at least 35 GBq/μmol. The GLP-1R-positive INS-1 insulinoma xenograft was clearly visible with good contrast to background, whereas GLP-1R-negative MDA-MB435 breast tumor was barely visible. Low levels of radioactivity were also detected at pancreas and lungs due to few GLP-1R expressions. GLP-1R binding specificity was demonstrated by reduced INS-1 tumor uptake of the tracer after coinjection with an excess of unlabeled Cys(39)-exendin-4 at 1 h postinjection.. The thiol-reactive reagent, (18)F-FBEM, was prepared with high yield and successfully conjugated to Cys(39)-exendin-4. Favorable preclinical data showing specific and effective tumor targeting by (18)F-FBEM-Cys(39)-exendin-4 suggest that the tracer may be a potential probe for insulinomas imaging.

Topics: Animals; Breast Neoplasms; Diagnostic Imaging; Exenatide; Female; Glucagon-Like Peptide-1 Receptor; Insulinoma; Maleimides; Mice; Mice, Inbred BALB C; Mice, Nude; Pancreatic Neoplasms; Peptides; Radiopharmaceuticals; Receptors, Glucagon; Venoms

The pathophysiological roles of thyroid hormones in glucose metabolism remain uncertain. Type 3 iodothyronine deiodinase (D3) converts thyroxine (T4) and 3,5,3'-triiodothyronine (T3) to 3,3',5'-triiodothyronine (rT3) and 3,3'-diiodothyronine (T2), respectively, inactivating thyroid hormones in a cell-specific fashion. In the present study, we identified D3 expression in MIN6 cells derived from a mouse insulinoma cell line and examined the mechanisms regulating D3 expression in these cells.. We characterized D3 activity using HPLC analysis, and examined the effect of GLP-1 or exendin-4 on D3 expression and cAMP accumulation in MIN6 cells. We also measured insulin secretion from MIN6 cells exposed to GLP-1 and T3.. We identified enzyme activity that catalyzes the conversion of T3 to T2 in MIN6 cells, which showed characteristics compatible with those for D3. D3 mRNA was identified in these cells using RT-PCR analysis. Forskolin rapidly stimulated D3 mRNA and D3 activity. Glucagon-like peptide-1 (GLP-1) increased D3 expression in a dose-dependent manner, and this effect was inhibited by the protein kinase A (PKA) inhibitor H-89. Exendin-4, a GLP-1 receptor agonist, also stimulated D3 expression in MIN6 cells. These results suggest that a cAMP-PKA-mediated pathway participates in GLP-1-stimulated D3 expression in MIN6 cells. Furthermore, GLP-1 stimulated insulin secretion was suppressed by the addition of T3 in MIN6 cells.. Our findings indicate that GLP-1 regulates intracellular T3 concentration in pancreatic β cells via a cAMP-PKA-D3-mediated pathway that may also regulate β-cell function.

Topics: Animals; Cell Line, Tumor; Colforsin; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Exenatide; Gene Expression Regulation, Neoplastic; Glucagon-Like Peptide 1; Insulin-Secreting Cells; Insulinoma; Iodide Peroxidase; Mice; Pancreatic Neoplasms; Peptides; RNA, Messenger; Signal Transduction; Triiodothyronine; Triiodothyronine, Reverse; Venoms

The transcription factor Hes3 is a component of a signaling pathway that supports the growth of neural stem cells with profound consequences in neurodegenerative disease models. Here we explored whether Hes3 also regulates pancreatic islet cells. We showed that Hes3 is expressed in human and rodent pancreatic islets. In mouse islets it co-localizes with alpha and beta cell markers. We employed the mouse insulinoma cell line MIN6 to perform in vitro characterization and functional studies in conditions known to modulate Hes3 based upon our previous work using neural stem cell cultures. In these conditions, cells showed elevated Hes3 expression and nuclear localization, grew efficiently, and showed higher evoked insulin release responses, compared with serum-containing conditions. They also exhibited higher expression of the transcription factor Pdx1 and insulin. Furthermore, they were responsive to pharmacological treatments with the GLP-1 analog Exendin-4, which increased nuclear Hes3 localization. We employed a transfection approach to address specific functions of Hes3. Hes3 RNA interference opposed cell growth and affected gene expression as revealed by DNA microarrays. Western blotting and PCR approaches specifically showed that Hes3 RNA interference opposes the expression of Pdx1 and insulin. Hes3 overexpression (using a Hes3-GFP fusion construct) confirmed a role of Hes3 in regulating Pdx1 expression. Hes3 RNA interference reduced evoked insulin release. Mice lacking Hes3 exhibited increased islet damage by streptozotocin. These data suggest roles of Hes3 in pancreatic islet function.

Topics: Adult; Animals; Basic Helix-Loop-Helix Transcription Factors; Blotting, Western; Cell Line, Tumor; Cell Nucleus; Cell Proliferation; Diabetes Mellitus, Experimental; DNA-Binding Proteins; Exenatide; Gene Expression; Gene Expression Profiling; Homeodomain Proteins; Humans; Hypoglycemic Agents; Insulin; Insulin Secretion; Insulinoma; Islets of Langerhans; Mice, Inbred C57BL; Mice, Mutant Strains; Mice, Obese; Microscopy, Confocal; Nerve Tissue Proteins; Pancreatic Neoplasms; Peptides; Repressor Proteins; Reverse Transcriptase Polymerase Chain Reaction; RNA Interference; Trans-Activators; Transcription Factors; Venoms

Insulinoma is a neuroendocrine tumor derived from the β cells of pancreatic islets. They are usually relatively inaccessible for surgical intervention. High expression levels of glucagon-like peptide-1 (GLP-1) receptor have been detected in insulinoma.. The aim of the study was to evaluate the potential of F-radiolabeled GLP-1 analog exendin-4 for the diagnosis of insulinoma using PET/computed tomography imaging.. The GLP-1 receptor-specific molecular probe [F]FB-exendin-4 was prepared by the conjugation of exendin-4 and N-succinimidyl-4-[F] fluorobenzoate ([F]SFB). High expression of GLP-1 by the RIN-m5f insulinoma line and GLP-1 receptor specificity were evaluated by determining the saturation curve for in-vitro binding of I-radiolabeled exendin-4 and by investigation of the competitive binding between I-radiolabeled and unlabeled exendin-4. Further, the in-vivo biodistribution and micro-PET/computed tomography images of insulinoma-bearing mice were studied.. An overall radiochemical yield of 35.6±2.3% (decay corrected, n=5) and specific radioactivity of around 30 GBq/µmol were achieved for [F]FB-exendin-4, and the radiochemical purity was over 98%. Both in-vitro and in-vivo studies confirmed the specificity of [F]FB-exendin-4 to insulinoma cells.. [F]FB-exendin-4 has been found to be an effective molecular imaging probe for detecting insulinomas.

Topics: Animals; Benzoates; Binding, Competitive; Exenatide; Female; Fluorine Radioisotopes; Glucagon-Like Peptide 1; Glucagon-Like Peptide-1 Receptor; Insulinoma; Isotope Labeling; Mice; Multimodal Imaging; Pancreatic Neoplasms; Peptides; Positron-Emission Tomography; Radiochemistry; Receptors, Glucagon; Succinimides; Tomography, X-Ray Computed; Venoms

Topics: Exenatide; Female; Humans; Indium Radioisotopes; Insulinoma; Male; Pancreatic Neoplasms; Pentetic Acid; Peptides; Tomography, Emission-Computed; Tomography, Emission-Computed, Single-Photon; Venoms

The objective of this article is to present a new method for the diagnosis of insulinoma with the use of [Lys(40)(Ahx-HYNIC-(99m)Tc/EDDA)NH2]-exendin-4.. Studies were performed in 11 patients with negative results of all available non-isotopic diagnostic methods (8 with symptoms of insulinoma, 2 with malignant insulinoma and 1 with nesidioblastosis). In all patients glucagon-like peptide-1 (GLP-1) receptor imaging (whole-body and single photon emission computed tomography/CT examinations) after the injection of 740 MBq of the tracer was performed.. Both sensitivity and specificity of GLP-1 receptor imaging were assessed to be 100 % in patients with benign insulinoma. In all eight cases with suspicion of insulinoma a focal uptake in the pancreas was found. In six patients surgical excision of the tumour was performed (type G1 tumours were confirmed histopathologically). In one patient surgical treatment is planned. One patient was disqualified from surgery. In one case with malignant insulinoma pathological accumulation of the tracer was found only in the region of local recurrence. The GLP-1 study was negative in the other malignant insulinoma patient. In one case with suspicion of nesidioblastosis, a focal accumulation of the tracer was observed and histopathology revealed coexistence of insulinoma and nesidioblastosis.. [Lys(40)(Ahx-HYNIC-(99m)Tc/EDDA)NH2]-exendin-4 seems to be a promising diagnostic tool in the localization of small insulinoma tumours, but requires verification in a larger series of patients.

Topics: Adolescent; Adult; Aged; Exenatide; Female; Glucagon-Like Peptide-1 Receptor; Humans; Hydrazines; Hypoglycemic Agents; Insulinoma; Male; Middle Aged; Nicotinic Acids; Organotechnetium Compounds; Pancreatic Neoplasms; Peptides; Radionuclide Imaging; Radiopharmaceuticals; Receptors, Glucagon; Venoms; Young Adult

Postmarketing reports have linked exenatide use with acute pancreatitis and pancreatic cancer, but a definitive relationship has yet to be established.. We conducted a retrospective cohort analysis of patients with type 2 diabetes with employer-provided health insurance from 2007 to 2009. Multivariate models estimated the association between exenatide use and acute pancreatitis and pancreatic cancer. We required at least 1 year of exenatide exposure in the pancreatic cancer analysis. Sensitivity analyses were conducted that quasirandomized exenatide use based on patient out-of-pocket costs.. Among 268,561 patients included in the acute pancreatitis analysis, only 2.6% used exenatide. Hospitalization for acute pancreatitis was rare (0.247% of patients). In unadjusted and adjusted analyses, patients who did not use exenatide were more likely to be hospitalized for acute pancreatitis (0.249% vs. 0.196% in unadjusted analysis), but the difference was not statistically significant in either analysis (P = 0.22 and P = 0.70, respectively). Among 209,306 patients in the pancreatic cancer analysis, 0.070% were diagnosed with pancreatic cancer, and 0.88% had at least 1 year of continuous exenatide exposure prior to the diagnosis. Those with exenatide exposure had higher rates of pancreatic cancer compared with those without (0.081% vs. 0.070% in unadjusted analysis). In both unadjusted and adjusted analyses, the difference was not statistically significant (P = 0.80 and P = 0.46, respectively). In sensitivity analyses, results were similar.. We found no association between exenatide use and either hospitalization for acute pancreatitis or pancreatic cancer in a large sample of privately insured U.S. patients.

Topics: Diabetes Mellitus, Type 2; Exenatide; Female; Hospitalization; Humans; Hypoglycemic Agents; Incidence; Insurance, Health; Logistic Models; Male; Middle Aged; Multivariate Analysis; Pancreatic Neoplasms; Pancreatitis; Peptides; Retrospective Studies; Risk Assessment; United States; Venoms

The glucagon-like peptide 1 receptor (GLP1R) plays a critical role in glucose metabolism and has become an important target for a growing class of drugs designed to treat type 2 diabetes. In vitro studies were designed to investigate the effect of the GLP1R agonist, exenatide (Ex4), in "on-target" RIN-5mF (islet) cells as well as in "off-target" AR42J (acinar) and DSL-6A/C1 (ductal) cells in a diabetic environment. Ex4 increased islet cell proliferation but did not affect acinar cells or ductal cells at relevant concentrations. A high caloric, high fat diet is a risk factor for impaired glucose tolerance and type-2 diabetes. An in vitro Oleic acid (OA) model was used to investigate the effect of Ex4 in a high calorie, high fat environment. At 0.1 and 0.4mM, OA mildly decreased the proliferation of all pancreatic cell types. Ex4 did not potentiate the inhibitory effect of OA on cell proliferation. Akt phosphorylation in response to Ex4 was diminished in OA-treated ductal cells. GLP1R protein detected by western blot was time and concentration dependently decreased after glucose stimulation in OA-treated ductal cells. In ductal cells, OA treatment altered the intracellular localization of GLP1R and its co-localization with early endosome and recycling endosomes. Chloroquine (lysosomal inhibitor), N-acetyl-l-cysteine (reactive oxygen species scavenger) and wortmannin (a phosphatidylinositol-3-kinase inhibitor), fully or partially, rescued GLP1R protein in OA-pretreated, glucose-stimulated ductal cells. The impact of altered regulation on phenotype/function is presently unknown. However, these data suggest that GLP1R regulation in ductal cells can be altered by a high fat, high calorie environment.

Topics: Acinar Cells; Animals; Blotting, Western; Cell Line; Cell Line, Tumor; Cell Proliferation; Cell Survival; Endosomes; Exenatide; Fluorescent Antibody Technique; Glucagon-Like Peptide-1 Receptor; Glucose; Islets of Langerhans; Microscopy, Confocal; Oleic Acid; Oncogene Protein v-akt; Pancreatic Ducts; Pancreatic Neoplasms; Peptides; Phosphorylation; Rats; Receptors, Glucagon; Stimulation, Chemical; Vacuoles; Venoms

Glucagon-like peptide-1-based therapy is gaining widespread use for type 2 diabetes, although there are concerns about risks for pancreatitis and pancreatic and thyroid cancers. There are also concerns that dipeptidyl peptidase-4 inhibitors could cause cancer, given their effects on immune function.. We examined the US Food and Drug Administration's database of reported adverse events for those associated with the dipeptidyl peptidase-4 inhibitor sitagliptin and the glucagon-like peptide-1 mimetic exenatide, from 2004-2009; data on adverse events associated with 4 other medications were compared as controls. The primary outcomes measures were rates of reported pancreatitis, pancreatic and thyroid cancer, and all cancers associated with sitagliptin or exenatide, compared with other therapies.. Use of sitagliptin or exenatide increased the odds ratio for reported pancreatitis 6-fold as compared with other therapies (P<2×10(-16)). Pancreatic cancer was more commonly reported among patients who took sitagliptin or exenatide as compared with other therapies (P<.008, P<9×10(-5)). All other cancers occurred similarly among patients who took sitagliptin compared with other therapies (P=.20).. These data are consistent with case reports and animal studies indicating an increased risk for pancreatitis with glucagon-like peptide-1-based therapy. The findings also raise caution about the potential long-term actions of these drugs to promote pancreatic cancer.

Topics: Adverse Drug Reaction Reporting Systems; Diabetes Mellitus, Type 2; Dipeptidyl-Peptidase IV Inhibitors; Exenatide; Glucagon-Like Peptide-1 Receptor; Humans; Hypoglycemic Agents; Odds Ratio; Pancreatic Neoplasms; Pancreatitis; Peptides; Pyrazines; Receptors, Glucagon; Risk Assessment; Risk Factors; Sitagliptin Phosphate; Thyroid Neoplasms; Triazoles; United States; United States Food and Drug Administration; Venoms

Topics: Diabetes Mellitus, Type 2; Dipeptidyl-Peptidase IV Inhibitors; Exenatide; Glucagon-Like Peptide-1 Receptor; Humans; Hypoglycemic Agents; Pancreatic Neoplasms; Pancreatitis; Peptides; Pyrazines; Receptors, Glucagon; Risk Assessment; Risk Factors; Sitagliptin Phosphate; Thyroid Neoplasms; Triazoles; Uncertainty; Venoms

Topics: Exenatide; Humans; Hypoglycemic Agents; Pancreatic Neoplasms; Pancreatitis; Peptides; Pyrazines; Sitagliptin Phosphate; Triazoles; Venoms

The aim of this study was to investigate the effect of exendin-4 on the expression of cyclin D1 gene (Ccnd1), which is critical in regulating the progression of the cell cycle in INS-1 cells.. INS-1 cells were stimulated with exendin-4 (10 nmol/l). Transient transfection and luciferase reporter assays were performed to measure promoter activities of rat Ccnd1. Electrophoretic mobility shift and chromatin immunoprecipitation assays were used to examine the binding of transcription factors to sites responsive to exendin-4 in vitro and in vivo, respectively.. Exendin-4 increased both Ccnd1 mRNA and its protein levels in a time-dependent manner. The region from -174 to +130 of the promoter was found to contain cis-regulatory elements responsible for exendin-4-mediated gene induction. Early growth response-1 (EGR1) protein was bound to the region from -153 to -134, which includes the putative EGR1 binding site (5'-CACCCCCGC-3'). Moreover, exendin-4 recruited EGR1 protein to the promoter in vivo.. These findings suggest that exendin-4 activates Ccnd1 transcription through induction of EGR1 binding to a cis-regulatory element between -153 and -134 on the rat Ccnd1 promoter. These results provide an important indication that exendin-4 is a growth factor regulating beta cell proliferation.

Topics: Animals; Base Sequence; Cell Division; Cell Line; Cyclin D; Cyclins; Exenatide; Gene Expression Regulation; Humans; Insulinoma; Islets of Langerhans; Molecular Sequence Data; Pancreatic Neoplasms; Peptides; Promoter Regions, Genetic; Rats; Rats, Sprague-Dawley; Regulatory Sequences, Nucleic Acid; RNA, Messenger; Sequence Alignment; Sequence Homology, Nucleic Acid; Transcription, Genetic; Transcriptional Activation; Venoms

1. The signal transduction pathway responsible for cAMP-dependent Ca2+-induced Ca2+ release (CICR) from endoplasmic reticulum Ca2+ stores was assessed in the insulin-secreting cell line INS-1. 2. CICR was triggered by the GLP-1 receptor agonist exendin-4, an effect mimicked by caffeine, Sp-cAMPS or forskolin. CICR required influx of Ca2+ through L-type voltage-dependent Ca2+ channels, and was blocked by treatment with nimodipine, thapsigargin, or ryanodine, but not by the IP3 receptor antagonist xestospongin C. 3. Treatment with the cAMP antagonist 8-Br-Rp-cAMPS blocked CICR in response to exendin-4, whereas the PKA inhibitor H-89 was ineffective when tested at a concentration demonstrated to inhibit PKA-dependent gene expression. 4. RT-PCR of INS-1 cells demonstrated expression of mRNA coding for the type-II isoform of cAMP-regulated guanine nucleotide exchange factor (cAMP-GEF-II, Epac2). 5. CICR in response to forskolin was blocked by transient transfection and expression of a dominant negative mutant isoform of cAMP-GEF-II in which inactivating mutations were introduced into the exchange factor's two cAMP-binding domains. 6. It is concluded that CICR in INS-1 cells results from GLP-1 receptor-mediated sensitization of the intracellular Ca2+ release mechanism, a signal transduction pathway independent of PKA, but which requires cAMP-GEF-II.

Topics: Animals; Caffeine; Calcium; Colforsin; Cyclic AMP; Cyclic AMP-Dependent Protein Kinase Type II; Cyclic AMP-Dependent Protein Kinases; Down-Regulation; Exenatide; Gene Expression; Guanine Nucleotide Exchange Factors; Insulinoma; Ion Channel Gating; Islets of Langerhans; Pancreatic Neoplasms; Peptides; Phosphodiesterase Inhibitors; Rats; Ryanodine Receptor Calcium Release Channel; Transfection; Tumor Cells, Cultured; Venoms

Glucagon-like peptide-1-(7---36) amide (GLP-1) is a potent incretin hormone secreted from distal gut. It stimulates basal and glucose-induced insulin secretion and proinsulin gene expression. The present study tested the hypothesis that GLP-1 may modulate insulin receptor binding. RINm5F rat insulinoma cells were incubated with GLP-1 (0.01-100 nM) for different periods (1 min-24 h). Insulin receptor binding was assessed by competitive ligand binding studies. In addition, we investigated the effect of GLP-1 on insulin receptor binding on monocytes isolated from type 1 and type 2 diabetes patients and healthy volunteers. In RINm5F cells, GLP-1 increased the capacity and affinity of insulin binding in a time- and concentration-dependent manner. The GLP-1 receptor agonist exendin-4 showed similar effects, whereas the receptor antagonist exendin-(9---39) amide inhibited the GLP-1-induced increase in insulin receptor binding. The GLP-1 effect was potentiated by the adenylyl cyclase activator forskolin and the stable cAMP analog Sp-5, 6-dichloro-1-beta-D-ribofuranosyl-benzimidazole-3', 5'-monophosphorothioate but was antagonized by the intracellular Ca(2+) chelator 1,2-bis(0-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-AM. Glucagon, gastric inhibitory peptide (GIP), and GIP-(1---30) did not affect insulin binding. In isolated monocytes, 24 h incubation with 100 nM GLP-1 significantly (P<0.05) increased the diminished number of high-capacity/low-affinity insulin binding sites per cell in type 1 diabetics (9,000+/-3,200 vs. 18,500+/-3,600) and in type 2 diabetics (15,700+/-2,100 vs. 28,900+/-1,800) compared with nondiabetic control subjects (25,100+/-2,700 vs. 26,200+/-4,200). Based on our previous experiments in IEC-6 cells and IM-9 lymphoblasts indicating that the low-affinity/high-capacity insulin binding sites may be more specific for proinsulin (Jehle, PM, Fussgaenger RD, Angelus NK, Jungwirth RJ, Saile B, and Lutz MP. Am J Physiol Endocrinol Metab 276: E262-E268, 1999 and Jehle, PM, Lutz MP, and Fussgaenger RD. Diabetologia 39: 421-432, 1996), we further investigated the effect of GLP-1 on proinsulin binding in RINm5F cells and monocytes. In both cell types, GLP-1 induced a significant increase in proinsulin binding. We conclude that, in RINm5F cells and in isolated human monocytes, GLP-1 specifically increases the number of high-capacity insulin binding sites that may be functional proinsulin receptors.

Topics: Adult; Animals; Exenatide; Female; Glucagon; Glucagon-Like Peptide 1; Glucagon-Like Peptide-1 Receptor; Glucagon-Like Peptides; Humans; Insulin; Insulinoma; Male; Monocytes; Pancreatic Neoplasms; Peptide Fragments; Peptides; Proinsulin; Protein Precursors; Rats; Receptors, Glucagon; Tumor Cells, Cultured; Venoms

In this article, we show that glucagon-like peptide 1 (GLP-1) can induce AR42J cells to differentiate into insulin, pancreatic polypeptide, and glucagon-positive cells. In their natural state, these cells, which are derived from a chemically induced pancreatic tumor, possess exocrine and neuroendocrine properties but are negative for islet hormones and their mRNAs. We found that when these cells were exposed to GLP-1 (1 or 10 nmol), a peptide normally released from the gut in response to food and a modulator of insulin release, intracellular cAMP levels were increased, and proliferation of cells was increased for the first 24 h, followed by inhibition. Up to 50% of the cells became positive for islet hormones. The mRNAs for glucose transporter 2 and glucokinase were detected in the GLP-1-treated cells. Insulin was detected by radioimmunoassay (RIA) in the medium of GLP-1-treated cells, and the cells were capable of releasing insulin in a glucose-mediated fashion. Exendin-4, an analog of GLP-1, in some critical experiments performed in a similar manner to GLP-1, with the exception of it being 10-fold more potent. We therefore propose that GLP-1 and exendin-4 are capable of causing pancreatic precursor cells to differentiate into islet cells.

Topics: Adenylyl Cyclases; Amylases; Animals; Cell Cycle; Cell Differentiation; Cholecystokinin; Dexamethasone; Exenatide; Gene Expression Regulation; Glucagon; Glucagon-Like Peptide 1; Insulin; Kinetics; Pancreatic Neoplasms; Peptide Fragments; Peptides; Protein Precursors; Rats; Reverse Transcriptase Polymerase Chain Reaction; Tumor Cells, Cultured; Venoms

Exendin-4 purified from Heloderma suspectum venom shows structural relationship to the important incretin hormone glucagon-like peptide 1-(7-36)-amide (GLP-1). We demonstrate that exendin-4 and truncated exendin-(9-39)-amide specifically interact with the GLP-1 receptor on insulinoma-derived cells and on lung membranes. Exendin-4 displaced 125I-GLP-1, and unlabeled GLP-1 displaced 125I-exendin-4 from the binding site at rat insulinoma-derived RINm5F cells. Exendin-4 had, like GLP-1, a pronounced effect on intracellular cAMP generation, which was reduced by exendin-(9-39)-amide. When combined, GLP-1 and exendin-4 showed additive action on cAMP. They each competed with the radio-labeled version of the other peptide in cross-linking experiments. The apparent molecular mass of the respective ligand-binding protein complex was 63,000 Da. Exendin-(9-39)-amide abolished the cross-linking of both peptides. Exendin-4, like GLP-1, stimulated dose dependently the glucose-induced insulin secretion in isolated rat islets, and, in mouse insulinoma beta TC-1 cells, both peptides stimulated the proinsulin gene expression at the level of transcription. Exendin-(9-39)-amide reduced these effects. In conclusion, exendin-4 is an agonist and exendin-(9-39)-amide is a specific GLP-1 receptor antagonist.

Topics: Animals; Binding, Competitive; Cell Line; Cell Membrane; Cyclic AMP; Exenatide; Glucagon; Glucagon-Like Peptide 1; Glucagon-Like Peptide-1 Receptor; Glucagon-Like Peptides; Insulin; Insulin Secretion; Insulinoma; Kinetics; Lizards; Lung; Pancreatic Neoplasms; Peptide Fragments; Peptides; Rats; Receptors, Cell Surface; Receptors, Glucagon; Tumor Cells, Cultured; Venoms