gastrins and Thyroid-Neoplasms

A wide variety of radiolabeled peptide analogs for specific targeting of cholecystokinin- 2 receptors (CCK2R) has been developed in the last decades. Peptide probes based on the natural ligands Minigastrin (MG) and Cholecystokinin (CCK) have a high potential for molecular imaging and targeted radiotherapy of different human tumors, such as Medullary Thyroid Carcinoma (MTC) and Small Cell Lung Cancer (SCLC). MG analogs with high persistent uptake in CCK2R expressing tumors have been preferably used for the development of radiolabeled peptide analogs. The clinical translation of CCK2R targeting has been prevented due to high kidney uptake or low metabolic stability of the different radiopeptides developed. Great efforts in radiopharmaceutical development have been undertaken to overcome these limitations. Various modifications in the linear peptide sequence of MG have been introduced mainly with the aim to reduce kidney retention. Furthermore, improved tumor uptake could be obtained by in situ stabilization of the radiopeptide against enzymatic degradation through coinjection of peptidase inhibitors. Recent developments focusing on the stabilization of the Cterminal receptor binding sequence (Trp-Met-Asp-Phe-NH2) have led to new radiolabeled MG analogs with highly improved tumor uptake and tumor-to-kidney ratio. In this review, all the different aspects in the radiopharmaceutical development of CCK2R targeting peptide probes are covered, giving also an overview on the clinical investigations performed so far. The recent development of radiolabeled MG analogs, which are highly stabilized against enzymatic degradation in vivo, promises to have a high impact on the clinical management of patients with CCK2R expressing tumors in the near future.

Topics: Cholecystokinin; Gastrins; Humans; Peptides; Radiopharmaceuticals; Receptor, Cholecystokinin B; Small Cell Lung Carcinoma; Thyroid Neoplasms

Cholecystokinin subtype 2 receptors (CCK2R) are overexpressed in several human cancers, including medullary thyroid carcinoma. Gastrin and cholecystokinin (CCK) peptides that bind with high affinity and specificity to CCK2R can be used as carriers of radioactivity to CCK2R-expressing tumor sites. Several gastrin and CCK related peptides have been proposed for diagnostic imaging and radionuclide therapy of primary and metastatic CCK2R-positive human tumors. Their clinical application has been restricted to a great extent by their fast in vivo degradation that eventually compromises tumor uptake. This problem has been addressed by structural modifications of gastrin and CCK motifs, which, however, often lead to suboptimal pharmacokinetic profiles. A major enzyme implicated in the catabolism of gastrin and CCK based peptides is neutral endopeptidase (NEP), which is widely distributed in the body. Coinjection of the NEP inhibitor phosphoramidon (PA) with radiolabeled gastrin and other peptide analogs has been recently proposed as a new promising strategy to increase bioavailability and tumor-localization of radiopeptides in tumor sites. Specifically, co-administration of PA with the truncated gastrin analog [(111)In-DOTA]MG11 ([((111)In-DOTA)DGlu(10)]gastrin(10-17)) impressively enhanced the levels of intact radiopeptide in mouse circulation and has led to an 8-fold increase of CCK2R-positive tumor uptake in SCID mice. This increased tumor uptake, visualized also by SPECT/CT imaging, is expected to eventually translate into higher diagnostic sensitivity and improved therapeutic efficacy of radiolabeled gastrin analogs in CCK2R-expressing cancer patients.

Topics: Animals; Carcinoma, Neuroendocrine; Cholecystokinin; Gastrins; Gene Expression Regulation, Neoplastic; Glycopeptides; Humans; Kidney; Kidney Neoplasms; Ligands; Mice; Mice, SCID; Models, Chemical; Neoplasm Transplantation; Neoplasms; Neprilysin; Peptides; Radiopharmaceuticals; Receptor, Cholecystokinin B; Thyroid Neoplasms; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed

Medullary thyroid cancer (MTC) originates from parafollicular C cells of the thyroid and accounts for 3-12% of all thyroid cancers. As opposed to other types of dedifferentiated thyroid tumours, MTC cells are highly functional, producing and secreting high amounts of calcitonin and carcinoembryonic antigen. As parafollicular C cells are of neural crest origin, MTC acts as a neuroendocrine tumour also and expresses somatostatin receptors. Although conventional radiological methods such as ultrasonography, computed tomography and magnetic resonance imaging are widely used in the primary diagnosis and staging, they often fail to localize the residual or recurrent disease because the majority of MTC recurrence presents as occult disease. Thus, owing to functional characteristics of MTC, functional imaging modalities of nuclear medicine play a major role in the diagnostic and therapeutic strategies for MTC. Among nuclear medicine modalities, Tc(V) -dimercaptosuccinic acid, In-octreotide and I/I-meta-iodobenzylguanidine are commonly used in the diagnostic and even more in postoperative work-up of MTC. Alternatively, F-fluorodeoxyglucose and other positron emission tomography radiopharmaceuticals such as F-fluorodopa or F-fluorodopamine as well as radiolabelled antibodies such as Tc/I/I anticarcinoembryonic antigen, antigastrin, and anticholecystokinin-B have promising results. Functional imaging has a great advantage for nuclear medicine techniques in the routine work-up of MTC patients and also has a wide use in experimental studies.

Topics: Aged; Antibodies; Carcinoembryonic Antigen; Carcinoma, Medullary; Female; Gastrins; Humans; Male; Middle Aged; Positron-Emission Tomography; Radiopharmaceuticals; Receptor, Cholecystokinin B; Receptors, Somatostatin; Thyroid Neoplasms; Tomography, X-Ray Computed

Today, calcitonin assay is used for the diagnosis of thyroid medullary cancer in the context of nodular thyroid disease. Calcitonin is an excellent marker of thyroid medullary cancer but some hypercalcitoninemia can also be related to other diseases, such as renal failure, endocrine tumors other than thyroid medullary cancer and sometimes to C cell hyperplasia, which is a not well-defined situation. Recent studies contributed to define calcitoninemia thresholds, which guide decision and avoid excessive invasive treatment.. After a brief reminder of physiological role of calcitonin and assays, the difficulties encountered in interpreting hypercalcitoninemia and its potential causes other than thyroid medullary cancer are addressed. Recent studies, on large series, now allow a better knowledge of specificity and sensitivity of calcitonin measurement in patients with nodular thyroid disease and a well-argued management.. In the future, calcitonin dosage will be ordered even more frequently, as some authors recommend it for the diagnosis of thyroid nodule. It is up to us to know how to use this remarkable marker, by considering all possible situations of benign hypercalcitoninemia and reserving aggressive treatments for patients who really need them.

Topics: Adult; Biomarkers; Calcitonin; Carcinoma, Medullary; Diagnosis, Differential; Endocrine Gland Neoplasms; Gastrins; Humans; Hypercalcemia; Hyperplasia; Kidney Failure, Chronic; Sensitivity and Specificity; Sepsis; Thyroid Diseases; Thyroid Gland; Thyroid Neoplasms; Thyroid Nodule

The high sensitivity of the pentagastrin stimulation test in detecting primary or metastatic medullary thyroid cancer (MTC) suggests a widespread expression of the corresponding receptor type on human MTC. Indeed, autoradiographic studies demonstrated cholecystokinin (CCK)-B/gastrin receptors not only in more than 90% of MTCs, but also in a high percentage of small-cell lung cancers, stromal ovarian tumors, and potentially a variety of other tumors, including gastrointestinal adenocarcinomas, neuroendocrine tumors, and malignant glioma. The aim of our work was to develop and systematically optimize suitable radioligands for targeting CCK-B receptors in vivo and to investigate their role in the staging and therapy of MTC and other CCK-B receptor expressing malignancies. For this purpose, a variety of CCK/gastrin-related peptides, all having in common the C-terminal CCK-receptor binding tetrapeptide sequence-Trp-Met-Asp-PheNH(2) or derivatives thereof, were investigated. They were members of the gastrin or cholecystokinin families or possessed characteristics of both, which differ by the intramolecular position of a tyrosyl moiety. Their stability and affinity were studied and optimized in vitro and in vivo; their biodistribution and therapeutic efficacy were tested in preclinical models. Best tumor uptake and tumor to nontumor ratios were obtained with members of the gastrin family, because of their superior selectivity and affinity for the CCK-B receptor subtype. Radiometal-labeled derivates of minigastrin showed excellent targeting of CCK-B receptor expressing tissues in animals and healthy human volunteers. Preclinical therapy experiments in MTC-bearing animals showed significant antitumor efficacy. In a subsequent clinical study, 45 MTC patients with metastatic MTC were investigated; 23 had known and 22 had occult disease. CCK-B receptor scintigraphy was performed with (111)In-diethylenetriamine pentaacetic acid-d-Glu(1)-minigastrin. The normal organ uptake was essentially confined to the stomach (and, to a lesser extent, to the gallbladder and, in premenopausal women, to normal breast tissue) as a result of CCK-B receptor specific binding and to the kidneys, as excretory organs. All tumor manifestations known from conventional imaging were visualized as early as 1 hour postinjection, with increasing tumor to background ratios over time; at least 1 lesion was detected in 20 of 22 patients with occult disease (patient-based sensitivity, 91%). Among them

Topics: Animals; Carcinoma, Medullary; Cholecystokinin; Gastrins; Humans; Neuroendocrine Tumors; Radionuclide Imaging; Radiopharmaceuticals; Receptor, Cholecystokinin B; Receptors, Cholecystokinin; Receptors, Somatostatin; Somatostatin; Thyroid Neoplasms

Histopathological and experimental observations indicate that tumors composed wholly or in part of neuroendocrine elements may arise in tissues derived from ectoderm (including neuroectoderm), mesoderm, and endoderm. These tumors frequently exhibit multidirectional differentiation as manifested by multihormonality and by the presence of morphological features indicative of divergent differentiation both in vivo and in vitro. The existence of stem cells, plasticity of differentiated cells, microenvironmental influences, and random events are factors which might all interact to determine the characteristics of any particular tumor. The production of characteristic regulatory peptide products in association with tumors of specific histological subtypes and with other neuroendocrine markers suggests mechanisms for nonrandom activation of multiple genes common to neuroendocrine-programmed cells. Future studies applying new molecular biological techniques to intact tissues and to in vitro models may help to clarify the mechanisms that regulate the expression of the neuroendocrine phenotype in normal and neoplastic states.

Topics: Adrenal Gland Neoplasms; Animals; Apudoma; Calcitonin; Carcinoid Tumor; Cricetinae; Female; Gastrins; Hormones, Ectopic; Humans; Neurotensin; Ovarian Neoplasms; Pancreatic Neoplasms; Pheochromocytoma; Rats; Somatostatin; Thyroid Neoplasms; Uterine Neoplasms; Vasoactive Intestinal Peptide

Topics: Acute Kidney Injury; Adenoma, Islet Cell; Apudoma; Dehydration; Gastrins; Gastrointestinal Hormones; Gastrointestinal Neoplasms; Humans; Multiple Endocrine Neoplasia; Pancreatic Neoplasms; Paraneoplastic Endocrine Syndromes; Parathyroid Neoplasms; Pheochromocytoma; Postgastrectomy Syndromes; Somatostatin; Syndrome; Thyroid Neoplasms; Zollinger-Ellison Syndrome

Topics: Animals; Calcitonin; Calcium; Digestive System Physiological Phenomena; Gastrins; Gastrointestinal Hormones; Humans; Parathyroid Hormone; Pentagastrin; Somatostatin; Thyroid Neoplasms

Topics: Adenoma, Islet Cell; Blood Glucose; Calcium; Endocrine System Diseases; Gastrins; Humans; Insulin; Multiple Endocrine Neoplasia; Pancreatic Neoplasms; Parathyroid Neoplasms; Pheochromocytoma; Pituitary Neoplasms; Radioimmunoassay; Syndrome; Thyroid Neoplasms; Zollinger-Ellison Syndrome

Somatostatin and gastrin receptors are overexpressed in medullary thyroid carcinoma (MTC) cells; hence, both of them are potential targets for peptide receptor scintigraphy and radiotherapy. Therefore, the aim of our study was to assess the clinical value of two technetium-99m-labeled peptides, a new gastrin analog, the EDDA/HYNIC-(D)Glu-octagastrin and a somatostatin analog, EDDA/HYNIC-Tyr(3)-octreotide (EDDA/HYNIC-TOC) for scintigraphy in patients with MTC to detect recurrences and metastases and select patients for peptide receptor radiotherapy.. Thirty (30) patients, 20 females and 10 males, 22-83 years of age (mean, 52.7) with the diagnosis of MTC in different stages of the disease (preoperative, postsurgery, remission, recurrence, or metastatic disease) were included in this study. Before surgery, in all patients serum calcitonin concentrations were elevated. The diagnosis of MTC was confirmed in all cases by histopathology of the removed tumor and immunohistochemical staining giving positive reactions for calcitonin and chromogranin A. Imaging studies using (99m)Tc-EDDA/HYNIC-TOC and a new minigastrin analog, (99m)Tc-EDDA/HYNIC-(D)Glu-octagastrin, were performed in each patient and the results compared with each other and with other imaging methods. Scans of the whole body, head, neck, and chest were performed 2 and 4 hours after injections of the tracer, 500-600 MBq in each case, using a double-head Varicam (Elscint, Israel) gamma camera.. (99m)Tc-EDDA/HYNIC-TOC detected somatostatin receptor-positive lesions in 20 patients with MTC, whereas (99m)Tc-EDDA/HYNIC-(D)Glu-octagastrin displayed gastrin receptors in 11 patients. In 9 cases, the scans were positive in both methods, although in 2 cases different pathologic foci were visualized. In 12 cases, only (99m)Tc-EDDA/HYNIC-TOC scintigraphy was positive, whereas in 3 other cases only (99m)Tc-EDDA/HYNIC-(D)Glu-octagastrin revealed pathologic lesions.. Scintigraphy using (99m)Tc-HYNIC-TOC permits the visualization of somatostatin receptor-positive MTC in the majority of cases. The new gastrin analog, (99m)Tc-HYNIC-(D)Glu-octagastrin, is well tolerated, shows no renal retention, and in some cases of MTC, provides additional information on the expression of gastrin receptors. However, inferior quality of octagastrin scans indicates the need for further improvement of this radiopeptide.

Topics: Adult; Aged; Aged, 80 and over; Animals; Carcinoma, Medullary; Edetic Acid; Female; Gastrins; Humans; Hydrazines; Indium Radioisotopes; Male; Mice; Mice, Inbred BALB C; Middle Aged; Neoplasm Metastasis; Neoplasm Recurrence, Local; Nicotinic Acids; Organotechnetium Compounds; Radionuclide Imaging; Sensitivity and Specificity; Thyroid Gland; Thyroid Neoplasms

The development of monofunctional DTPA derivatives has been a major breakthrough in the labelling of proteins or peptides with a variety of radiometals. Although this methodology is simple and useful for indium-111 labelling, the stability of these conjugates is too low for most therapeutic nuclides. Cyclic chelators, such as DOTA, have shown excellent kinetic stability with a variety of radiometals, but the labelling procedure is more difficult, requiring ultra-pure reagents and a heating step that sometimes endangers the biomolecule's integrity. The aim of this work was twofold: (a) to develop a novel, open chain chelator which can be easily labelled with various radiometals, displaying higher kinetic stability than monofunctional DTPA, and (b) to evaluate this chelator in vitro and in vivo when conjugated to a CCK-B receptor ligand as a detection modality for receptor-(over-)expressing tumours. DTPA derivatives of Leu(1)- and dGlu(1)-minigastrin were synthesised. All conjugates could be labelled with (111)In or (88/90)Y at high specific activities (8.5-44.4 GBq/micro mol) and with high radiochemical purity. Serum stability testing was performed, and the labelled conjugates were compared concerning their stability against DTPA challenge. The biodistribution of the radiolabelled Leu(1)- and dGlu(1)-minigastrin derivatives was studied in tumour-bearing nude mice, in one healthy human volunteer and in three patients with metastatic medullary thyroid carcinoma. The transchelation of all tested radiometals to serum proteins was significantly slower with the DTPA-Glu conjugates as compared with their Leu analogues (e.g. transchelation t(1/2) of DTPA- dGlu(1)-minigastrin vs its Leu(1) analogue at 37 degrees C in human serum for (111)In: 239 h vs 91 h; for (90)Y: 130 h vs 53 h). In animals, all labelled CCK-B receptor ligands showed fast and specific uptake in CCK-B-receptor-positive tissues, such as the stomach and tumour, as well as a fast renal clearance pattern. However, DTPA-Leu(1)-minigastrin showed higher background activity in the whole body and those organs known to accumulate the respective free radiometal (e.g. (88)Y-DTPA-Leu(1)-minigastrin had bone uptake of 22%ID/g as compared to only 1.2%ID/g with its dGlu(1) analogue). In humans, fast tumour and stomach uptake was observed for both (111)In-labelled compounds, but DTPA- dGlu(1)-minigastrin lacked the liver, spleen and bone marrow uptake observed with its Leu(1) analogue. In conclusion, anionic ami

Topics: Animals; Carcinoma, Medullary; Cell Line, Tumor; Chelating Agents; Drug Evaluation, Preclinical; Drug Stability; Female; Gastrins; Humans; Indium Radioisotopes; Kinetics; Male; Metabolic Clearance Rate; Mice; Mice, Nude; Organ Specificity; Pentetic Acid; Radionuclide Imaging; Radiopharmaceuticals; Staining and Labeling; Thyroid Neoplasms; Tissue Distribution; Whole-Body Counting; Yttrium Radioisotopes

A variety of radiolabelled minigastrin analogues targeting the cholecystokinin 2 (CCK2) receptor were developed and compared in a concerted preclinical testing to select the most promising radiotracer for diagnosis and treatment of medullary thyroid carcinoma (MTC). DOTA-DGlu-DGlu-DGlu-DGlu-DGlu-DGlu-Ala-Tyr-Gly-Trp-Met-Asp-Phe-NH2 (CP04) after labelling with (111)In displayed excellent characteristics, such as high stability, receptor affinity, specific and persistent tumour uptake and low kidney retention in animal models. Therefore, it was selected for further clinical evaluation within the ERA-NET project GRAN-T-MTC. Here we report on the development of a pharmaceutical freeze-dried formulation of the precursor CP04 for a first multi-centre clinical trial with (111)In-CP04 in MTC patients.. The kit formulation was optimised by adjustment of buffer, additives and radiolabelling conditions. Three clinical grade batches of a final kit formulation with two different amounts of peptide (10 or 50 μg) were prepared and radiolabelled with (111)In. Quality control and stability assays of both the kits and the resulting radiolabelled compound were performed by HPLC analysis.. Use of ascorbic acid buffer (pH4.5) allowed freeze-drying of the kit formulation with satisfactory pellet-formation. Addition of methionine and gentisic acid as well as careful selection of radiolabelling temperature was required to avoid extensive oxidation of the Met(11)-residue. Trace metal contamination, in particular Zn, was found to be a major challenge during the pharmaceutical filling process in particular for the 10 μg formulation. The final formulations contained 10 or 50 μg CP04, 25mg ascorbic acid, 0.5mg gentisic acid and 5mg L-methionine. The radiolabelling performed by incubation of 200-250 MBq (111)InCl3 at 90 °C for 15 min resulted in reproducible radiochemical purity (RCP) >94%. Kit-stability was proven for >6 months at +5 °C and at +25 °C. The radiolabelled product was stable for >4h at +25 °C.. A kit formulation to prepare (111)In-CP04 for clinical application was developed, showing high stability of the kit as well as high RCP of the final product.

Topics: Carcinoma, Neuroendocrine; Chemistry, Pharmaceutical; Clinical Trials as Topic; Drug Stability; Freeze Drying; Gastrins; Humans; Indium Radioisotopes; Methionine; Multicenter Studies as Topic; Peptides; Radioisotopes; Radiopharmaceuticals; Thyroid Neoplasms

a 75-year-old man with a 10-year history of nodular goitre was referred for clinical evaluation. The ultrasound scan revealed enlarged thyroid right lobe almost fully filled with a heterogeneous nodule with numerous calcifications. Fine-needle aspiration biopsy suggested medullary thyroid carcinoma (MTC). Before the surgery the patient was referred to the nuclear medicine department and somatostatin receptor imaging (SRS; 68Ga-DOTATATE) with PET/CT was performed. The scan demonstrated an increased uptake within the right thyroid mass. Subsequent PET/CT with 68Ga-gastrin analogue (MG48) revealed the same indications as the SRS: an increased alveolar uptake in the right thyroid mass without the signs of lymph node metastases. The patient underwent total thyroidectomy and central lymph nodes dissection. Histopathology examination confirmed the presence of MTC with vascular invasion, but without lymph node metastases (pT3NoMx according to the 7th edition of the AJCC Cancer Staging Manual). Immunohistochemical staining revealed positive reaction to calcitonin and CD56, whereas the reaction to thyroglobulin remained negative. The Ki-67 was 1%. Staining for SSTR2 and CCK2 showed high cytoplasmic expression in both cases. Knowledge of the presence of CCK2 receptor in MTC patients may be an important indication for the choice of diagnostic and therapeutic procedures. The presence of both the receptor types, cholecystokinin-2/gastrin and somatostatin, is possibly an interesting combination as far as the therapeutic target is concerned.

Topics: Aged; Carcinoma, Neuroendocrine; Gastrins; Humans; Male; Organometallic Compounds; Positron Emission Tomography Computed Tomography; Receptor, Cholecystokinin B; Receptors, Somatostatin; Somatostatin; Thyroid Neoplasms; Thyroidectomy

From a series of radiolabelled cholecystokinin (CCK) and gastrin analogues, (111)In-CP04 ((111)In-DOTA-(DGlu)6-Ala-Tyr-Gly-Trp-Met-Asp-Phe-NH2) was selected for further translation as a diagnostic radiopharmaceutical towards a first-in-man study in patients with medullary thyroid carcinoma (MTC). A freeze-dried kit formulation for multicentre application has been developed. We herein report on biosafety, in vivo stability, biodistribution and dosimetry aspects of (111)In-CP04 in animal models, essential for the regulatory approval of the clinical trial.. Acute and extended single dose toxicity of CP04 was tested in rodents, while the in vivo stability of (111)In-CP04 was assessed by HPLC analysis of mouse blood samples. The biodistribution of (111)In-CP04 prepared from a freeze-dried kit was studied in SCID mice bearing double A431-CCK2R(±) xenografts at 1, 4 and 24h pi. Further 4-h animal groups were either additionally treated with the plasma expander gelofusine or injected with (111)In-CP04 prepared by wet-labelling. Pharmacokinetics in healthy mice included the 30min, 1, 4, 24, 48 and 72h time points pi. Dosimetric calculations were based on extrapolation of mice data to humans adopting two scaling models.. CP04 was well-tolerated by both mice and rats, with an LD50>178.5μg/kg body weight for mice and a NOAEL (no-observed-adverse-effect-level) of 89μg/kg body weight for rats. After labelling, (111)In-CP04 remained >70% intact in peripheral mouse blood at 5min pi. The uptake of (111)In-CP04 prepared from the freeze-dried kit and by wet-labelling were comparable in the A431-CCK2R(+)-xenografts (9.24±1.35%ID/g and 8.49±0.39%ID/g, respectively; P>0.05). Gelofusine-treated mice exhibited significantly reduced kidneys values (1.69±0.15%ID/g vs. 5.55±0.94%ID/g in controls, P<0.001). Dosimetry data revealed very comparable effective tumour doses for the two scaling models applied, of 0.045 and 0.044mSv/MBq.. The present study has provided convincing toxicology, biodistribution and dosimetry data for prompt implementation of the freeze-dried kit formulation without or with gelofusine administration in a multicentre clinical trial in MTC patients.

Topics: Animals; Carcinoma, Neuroendocrine; Clinical Trials, Phase I as Topic; Drug Evaluation, Preclinical; Female; Gastrins; Humans; Indium Radioisotopes; Lethal Dose 50; Male; Mice; No-Observed-Adverse-Effect Level; Radiation Dosage; Radiopharmaceuticals; Rats; Rats, Wistar; Thyroid Neoplasms; Tissue Distribution

Targeting of cholecystokinin receptor expressing malignancies such as medullary thyroid carcinoma is currently limited by low in vivo stability of radioligands. To increase the stability, we have developed and preclinically evaluated two cyclic 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-minigastrin analogs radiolabeled with (111)In and (68)Ga.. Radiolabeling efficiency, in vitro characterization, cholecystokinin receptor subtype 2 (CCK-2) binding in human tumor tissues, and cell internalization on CCK-2 receptor expressing AR42J cells, as well as biodistribution and small animal imaging in two different mouse xenograft models were studied.. High receptor affinity and receptor-mediated uptake of the radioligands in AR42J cells was confirmed in vitro. (111)In-labeled cyclic DOTA-peptides showed a specific tumor uptake of ~1% ID/g in vivo, (68)Ga-labeled analogs of ~3% ID/g. Small animal SPECT imaging resulted to be superior with (111)In-DOTA-cyclo-MG2 in comparison with (111)In-DOTA-cyclo-MG1.. Cyclic DOTA-minigastrin analogs are promising candidates for gastrin receptor scintigraphy and targeted radionuclide therapy.

Topics: Animals; Carcinoma, Neuroendocrine; Cell Line, Tumor; Drug Evaluation, Preclinical; Female; Gallium Radioisotopes; Gastrins; Heterocyclic Compounds, 1-Ring; Indium Radioisotopes; Mice; Mice, Inbred BALB C; Mice, Nude; Mice, SCID; Receptors, Cholecystokinin; Thyroid Neoplasms; Tomography, Emission-Computed, Single-Photon

To be able to evaluate new radiopharmaceuticals and optimize diagnostic and therapeutic procedures, relevant animal models are required. The aim of this study was to evaluate the medullary thyroid carcinoma GOT2 animal model by analyzing the biodistribution of 177Lu-octreotate and 111In-minigastrin (MG0). BALB/c nude mice, subcutaneously transplanted with GOT2, were intravenously injected with either 177Lu-octreotate or 111In-MG0, with or without excess of unlabeled human minigastrin simultaneously with 111In-MG0. Animals were sacrificed 1-7 days after injection in the 177Lu-octreotate study and 1 h after injection of 111In-MG0. The activity concentrations in organs and tissues were determined and mean absorbed doses from 177Lu were calculated. There was a specific tumor uptake of either 177Lu-octreotate or 111In-MG0. 177Lu-octreotate samples showed high activity concentrations in tissues expressing somatostatin receptors (SSTR). For both radiopharmaceuticals the highest activity concentrations were found in the kidneys. Compared to results from similar studies in mice with another MTC cell line (TT) the biodistribution was favorable (higher tumor uptake) for the GOT2 model, while compared to other animal models expressing SSTR, the tumor uptake of 177Lu-octreotate was modest. In conclusion, the GOT2 animal model is a valuable model for evaluation and optimization of diagnostic and therapeutic procedures using radiolabeled somatostatin, CCK2 and gastrin analogues prior to clinical studies.

Topics: Animals; Carcinoma, Neuroendocrine; Cell Line, Tumor; Disease Models, Animal; Female; Gastrins; Humans; Indium Radioisotopes; Mice; Mice, Nude; Octreotide; Radionuclide Imaging; Radiopharmaceuticals; Thyroid Neoplasms; Tissue Distribution; Transplantation, Heterologous

The cholecystokinin-2 receptor (CCK2R), is expressed in cancers where it contributes to tumor progression. The CCK2R is over-expressed in a sub-set of tumors, allowing its use in tumor targeting with a radiolabel ligand. Since discrepancies between mRNA levels and CCK2R binding sites were noticed, we searched for abnormally spliced variants in tumors from various origins having been previously reported to frequently express cholecystokinin receptors, such as medullary thyroid carcinomas, gastrointestinal stromal tumors, leiomyomas and leiomyosarcomas, and gastroenteropancreatic tumors. A variant of the CCK2R coding for a putative five-transmembrane domains receptor has been cloned. This variant represented as much as 6% of CCK2R levels. Ectopic expression in COS-7 cells revealed that this variant lacks biological activity due to its sequestration in endoplasmic reticulum. When co-expressed with the CCK2R, this variant diminished membrane density of the CCK2R and CCK2R-mediated activity (phospholipase-C and ERK activation). In conclusion, a novel splice variant acting as a dominant negative on membrane density of the CCK2R may be of importance for the pathophysiology of certain tumors and for their in vivo CCK2R-targeting.

Topics: Alternative Splicing; Amino Acid Sequence; Animals; Binding Sites; Carcinoma, Medullary; Chlorocebus aethiops; Cholecystokinin; COS Cells; Extracellular Signal-Regulated MAP Kinases; Gastrins; Gastrointestinal Neoplasms; Gastrointestinal Stromal Tumors; Humans; Insulinoma; Leiomyoma; Leiomyosarcoma; Molecular Sequence Data; Pancreatic Neoplasms; Protein Structure, Tertiary; Receptor, Cholecystokinin B; RNA, Messenger; Signal Transduction; Thyroid Neoplasms; Type C Phospholipases

Medullary thyroid carcinoma (MTC) expresses CCK-2 receptors. (111)In-labeled DOTA-DGlu-Ala-Tyr-Gly-Trp-Met-Asp-Phe-NH(2) (DOTA-MG11), DOTA-DAsp-Tyr-Nle-Gly-Trp-Nle-Asp-Phe-NH(2) (DOTA-CCK), and (99m)Tc-labeled N(4)-Gly-DGlu-(Glu)(5)-Ala-Tyr-Gly-Trp-Met-Asp-Phe-NH(2) ((99m)Tc-Demogastrin 2) are analogs developed for CCK-2 receptor-targeted scintigraphy. All 3 radiolabeled analogs were selected on the basis of their high CCK-2 receptor affinity and their good in vitro serum stability, with in vitro serum t(1/2) values of several hours. Radiolabeling of DOTA-peptides with (111)In requires a heating procedure, typically in the range of 80 degrees -100 degrees C up to 30 min. Following this procedure with DOTA-MG11 resulted in a >98 % incorporation of (111)In, however, with a radiochemical purity (RCP) of <50 %. The decrease in RCP was found to be due to oxidation of the methionine residue in the molecule. Moreover, this oxidized compound lost its CCK-2 receptor affinity. Therefore, conditions during radiolabeling were optimised: labeling of DOTA-MG11 and DOTA-CCK with (111)In involved 5 min heating at 80 degrees C and led to an incorporation of (111)In of >98 %. In addition, all analogs were radiolabeled in the presence of quenchers to prevent radiolysis and oxidation resulting in a RCP of >90 %. All 3 radiolabeled analogs were i.v. administered to 6 MTC patients: radioactivity cleared rapidly by the kidneys, with no significant differences in the excretion pattern of the 3 radiotracers. All 3 radiolabeled analogs exhibited a low in vivo stability in patients, as revealed during analysis of blood samples, with the respective t(1/2) found in the order of minutes. In patient blood, the rank of radiopeptide in vivo stability was: (99m)Tc-Demogastrin 2 (t(1/2) 10-15 min)>(111)In-DOTA-CCK (t(1/2) approximately 5-10 min)>(111)In-DOTA-MG11 (t(1/2)<5 min).

Topics: Adolescent; Adult; Aged; Autoradiography; Carcinoma, Medullary; Chromatography, High Pressure Liquid; Drug Stability; Female; Gastrins; Humans; Isotope Labeling; Male; Middle Aged; Radioligand Assay; Radionuclide Imaging; Radiopharmaceuticals; Receptor, Cholecystokinin B; Thyroid Neoplasms

Different attempts have been made to develop a suitable radioligand for targeting CCK-2 receptors in vivo, for staging of medullary thyroid carcinoma (MTC) and other receptor-expressing tumours. After initial successful clinical studies with [DTPA(0),D: Glu(1)]minigastrin (DTPA-MG0) radiolabelled with (111)In and (90)Y, our group developed a (99m)Tc-labelled radioligand, based on HYNIC-MG0. A major drawback observed with these derivatives is their high uptake by the kidneys. In this study we describe the preclinical evaluation of the optimised shortened peptide analogue, [HYNIC(0),D: Glu(1),desGlu(2-6)]minigastrin (HYNIC-MG11).. (99m)Tc labelling of HYNIC-MG11 was performed using tricine and EDDA as coligands. Stability experiments were carried out by reversed phase HPLC analysis in PBS, PBS/cysteine and plasma as well as rat liver and kidney homogenates. Receptor binding and cell uptake experiments were performed using AR4-2J rat pancreatic tumour cells. Animal biodistribution was studied in AR4-2J tumour-bearing nude mice.. Radiolabelling was performed at high specific activities and radiochemical purity was >90%. (99m)Tc-EDDA-HYNIC-MG11 showed high affinity for the CCK-2 receptor and cell internalisation comparable to that of (99m)Tc-EDDA-HYNIC-MG0. Despite high stability in solution, a low metabolic stability in rat tissue homogenates was found. In a nude mouse tumour model, very low unspecific retention in most organs, rapid renal excretion with reduced renal retention and high tumour uptake were observed.. (99m)Tc-EDDA-HYNIC-MG11 shows advantages over (99m)Tc-EDDA-HYNIC-MG0 in terms of lower kidney retention with unchanged uptake in tumours and CCK-2 receptor-positive tissue. However, the lower metabolic stability and impurities formed in the labelling process still leave room for further improvement.

Topics: Animals; Carcinoma, Medullary; Cysteine; Edetic Acid; Gastrins; Gene Expression Regulation, Neoplastic; Glycine; Humans; Kidney; Liver; Neoplasms; Organotechnetium Compounds; Radionuclide Imaging; Rats; Receptor, Cholecystokinin B; Technetium; Thyroid Neoplasms; Tissue Distribution

The objective of this study was to re-evaluate the adult C(T) reference values determined by five different immunoassays and by introducing criteria for selecting control subjects.. A prospective multicenter study.. Three hundred and seventy-five clinically euthyroid subjects.. We used five different C(T) immunoassays. Sera were assayed for the concentration of TSH, gastrin, procalcitonin, urea, calcium, and anti-thyroperoxidase antibodies.. Screening for the various potential causes of hypercalcitoninemia led to the exclusion of 23% of the sera. Our reference value analysis dealt with 287 subjects (142 men and 145 women). The proportion of samples in which no C(T) was detected varied from 56% (for assay D) to 88% (for assay C). We observed significant correlations (whose magnitude depended on the assay used) between C(T) levels and age or body mass index (BMI) (primarily in men). The distribution of C(T) levels showed that 4.7, 9.8, 2.5, 6.5, and 8.0% of the values were over 10 pg/ml respectively. These values corresponded essentially to samples from 11 male subjects (median age: 55 years), most of whom were smokers. The highest C(T) values were around twice as high in men than women, and were higher in smokers than non-smokers. Conclusion In clinical practice (and after having excluded the usual causes of raised C(T) levels), the interpretation of C(T) assay results must take into account i) the method used; ii) the patient's gender, age, and weight; and iii) the potential influence of cigarette smoking.

Topics: Adolescent; Adult; Age Factors; Aged; Aged, 80 and over; Antibodies; Biomarkers, Tumor; Calcitonin; Calcitonin Gene-Related Peptide; Calcium; Carcinoma, Medullary; Female; Gastrins; Humans; Immunoassay; Iodide Peroxidase; Male; Middle Aged; Prospective Studies; Protein Precursors; Reagent Kits, Diagnostic; Reference Values; Smoking; Thyroid Neoplasms; Thyrotropin; Urea

Uptake of radiolabeled peptides in the kidneys may obscure abdominal tumors in radiopeptide scintigraphy. This problem is much more pronounced in peptide receptor radionuclide therapy (i.e., radiopeptide therapy), possibly leading to renal damage or even failure. Cationic peptide uptake in the kidneys can be reduced by the application of cationic amino acids, such as lysine or arginine. The aim of this study was to develop a suitable method to reduce anionic peptide uptake in the kidneys. (111)In-Diethylenetriaminepentaacetic acid dGlu(1)-minigastrin ((111)In-DTPA-dGlu-Glu-Glu-Glu-Glu-Glu-Ala-Tyr-Gly-Trp-Met-Asp-Phe-NH(2)) was chosen as a model compound with a sequence of 6 negatively charged glutamic acids in a chain and an additional aspartic acid.. TT (human medullary carcinoma cells)-bearing nu/nu mice of the Institute of Cancer Research genotype received intraperitoneal injections of different chain lengths and weights of glutamic acids, aspartic acids, and derivatives of glutamic acids. Uptake in tumors and organs was determined and compared with the values for untreated control mice.. Accretion of (111)In-DTPA-dGlu(1)-minigastrin in the kidneys could be reduced by up to 90%. The uptake values for all other organs and the tumors were not affected. These results were obtained with a chain of 5 or more glutamic acids, whereas uptake in kidneys was affected not at all or only slightly with poly-d-glutamic or polyaspartic acids and with Glu(x) (x = 1-4).. These studies indicated a specific blocking of uptake by Glu(5) sequences in the kidneys. Application of polyglutamic acids is a new, successful method of reducing uptake of negatively charged peptides in the kidneys during radiopeptide therapy.

Topics: Animals; Aspartic Acid; Carcinoma, Medullary; Female; Gastrins; Humans; Indium Radioisotopes; Kidney; Mice; Mice, Nude; Polyglutamic Acid; Radiopharmaceuticals; Structure-Activity Relationship; Thyroid Neoplasms; Tissue Distribution; Transplantation, Heterologous; Tumor Cells, Cultured

Gastrin-induced release of calcitonin from medullary thyroid carcinomas (MTC) is based on the expression of the cholecystokinin(2)-receptor (CCK(2)R) in these tumors. Recently, we have shown that the CCK(2)R is expressed not only in MTC but also in C-cells within the normal thyroid gland. The functions of the CCK(2)R in MTC and C-cells are largely unknown. We therefore explored the effects of gastrin-induced CCK(2)R stimulation in the highly differentiated MTC cell line, TT. CCK(2)R expression in TT-cells is detectable by RT-PCR as well as immunocytochemistry. Stimulation of the CCK(2)R by gastrin induces immediate release of calcitonin from TT-cells. Moreover, quantitative (LightCycler) RT-PCR demonstrates that gastrin stimulates transcription of the calcitonin and chromogranin A genes in TT-cells. TT-cell proliferation, assessed by counting of viable cells and (3)H-thymidine uptake, is markedly increased by gastrin. This effect is inhibited by the CCK(2)R-specific antagonist L-365,260. Our findings suggest physiological functions for the CCK(2)R in calcitonin-secretion and gene expression as well as a pathophysiological role in MTC proliferation. CCK(2)R antagonists might have therapeutic potential in these tumors.

Topics: Calcitonin; Carcinoma, Medullary; Cell Division; Cell Line, Tumor; Chromogranin A; Chromogranins; Gastrins; Gene Expression Regulation, Neoplastic; Humans; Receptor, Cholecystokinin B; Thyroid Neoplasms; Time Factors

We report a rare case of virilizing adrenocortical adenoma complicated with Cushing's syndrome, thyroid papillary carcinoma and hypergastrinemia. A 45-year-old woman had a history of amenorrhea for 10 years, hypertension for 8 years, and diabetes mellitus for 3 years. Physical examination showed a masculinized woman with severe hirsutism, male-like baldness, deep voice, acne in the precordia, and clitorism. Plasma testosterone, DHEA-S and urinary 17-KS were high, and plasma cortisol level was it at the upper limit of the normal range, but it did not show a diurnal rhythm nor was suppressed by 2 and 8 mg of dexamethasone. Abdominal CT scan showed a left adrenal tumor (4.5 cm in size). Adrenal scintigram revealed uptake of the tracer on the left side, and plasma cortisol concentration was high in a blood sample from the left adrenal vein. Left adrenalectomy was performed. Histopathological features of resected adrenal tumor were consistent with those of adrenocortical adenoma, consisting of tumor cells with eosinophilic compact cytoplasm. Immunohistochemical staining for steroidogenic enzymes showed reactivity for P450sec, 3 beta-HSD, P450c17, P450c21 and P450c11. Plasma testosterone and cortisol levels decreased to the normal range postoperatively. The patient was also found to have a papillary thyroid carcinoma and hypergastrinemia. Our patient is a rare case of virilizing adrenocortical adenoma associated with Cushing's syndrome, thyroid papillary carcinoma, and hypergastrinemia.

Topics: Adrenal Cortex Neoplasms; Adrenalectomy; Adrenocortical Adenoma; Angiography; Carcinoma, Papillary; Cushing Syndrome; Female; Gastrins; Humans; Middle Aged; Multiple Endocrine Neoplasia; Radionuclide Imaging; Thyroid Neoplasms; Tomography, X-Ray Computed; Virilism

Nuclear medicine is engaged with the detection of pathological processes with the help of radionuclides. An interesting approach is to target antigens, symporters, or receptors with diagnostic and therapeutic radionuclides. Different peptide receptors like somatostatin, bombesin/GRP or VIP are (over)expressed on cancer cells, and are therefore an ideal target for the diagnosis and therapy in nuclear medicine with radiolabeled peptides. The somatostatin analogue OctreoScan [octreotide coupled with diethylene-triamine-pentaacetate (DTPA)] can be labeled with In-111 and is widely used in nuclear oncology for the staging of different tumors (e.g., carcinoids). Other peptides like neurotensin, bombesin/GRP, and VIP are under (pre)clinical investigations. The staging of metastatic medullary thyroid cancer (MTC) with the conventional radiological procedures is sometimes difficult. The high sensitivity of the pentagastrin stimulation test in detecting primary or metastatic MTC indicates the presence of tumor, but its localization is often not possible. This reaction of the tumor cells to the pentagastrin stimulation test suggests a widespread expression of the corresponding receptor type on human MTC. Indeed, autoradiographic studies demonstrated cholecystokinin (CCK)-B/gastrin receptors not only in over 90% of MTCs, but in a high percentage of small cell lung cancers, stromal ovarian, and potentially a variety of other tumors, including gastrointestinal adenocarcinomas, neuroendocrine tumors, and malignant glioma. The aim of our recent work was to develop and systematically optimize suitable radioligands for targeting CCK-B receptors in vivo and to investigate their role in the staging and therapy of MTC and other CCK-B receptor expressing malignancies. For this purpose, a variety of CCK/gastrin-related peptides, all having in common the C-terminal CCK receptor binding tetrapeptide sequence -Trp-Met-Asp-PheNH(2) or derivatives thereof, were investigated. They were members of the gastrin- or cholecystokinin families, or possessed characteristics of both, which differ by the intramolecular position of a tyrosyl moiety. Their stability and affinity were studied and optimized in vitro and in vivo; their biodistribution and therapeutic efficacy were tested in preclinical models. Best tumor uptake and tumor-to-nontumor ratios were obtained with members of the gastrin family, due to their superior selectivity and affinity for the CCK-B receptor subtype. Radiometal-labe

Topics: Animals; Gastrins; Humans; Ligands; Mice; Pentetic Acid; Peptides; Radiopharmaceuticals; Receptor, Cholecystokinin B; Receptors, Cholecystokinin; Receptors, Somatostatin; Thyroid Neoplasms

The cholecystokinin(2)-receptor (CCK(2)R) promotes secretion and cell growth induced by its ligands cholecystokinin (CCK) and gastrin. The receptor has recently been shown to be expressed in human medullary thyroid carcinomas (MTCs). The objective of this study was to analyze CCK(2)R expression in MTC samples of different tumor stages as well as in non-malignant thyroid tissues.. Using RT-PCR we investigated 19 MTC samples and TT-cells (a human MTC cell line), as well as samples of normal thyroid. In addition, we performed immunohistochemistry using calcitonin- and CCK(2)R-specific antibodies on MTCs and samples of C-cell hyperplasia.. We demonstrate for the first time that CCK(2)R is expressed not only in MTCs but in all samples of normal thyroid tissue. Using immunohistochemistry the receptor could be localized on calcitonin-secreting C-cells. The highest incidence of CCK(2)R expression in MTCs was observed in early-tumor stages, whereas CCK(2)R could not be detected in advanced or metastasized tumors.. The expression of CCK(2)R in C-cells suggests a physiological function for gastrin and/or CCK in the regulation of calcitonin release, presumably related to bone and calcium metabolism. Moreover, these ligands might act as growth factors in MTCs. Efforts in the development of CCK(2)R scintigraphy for the detection of MTC lesions might have to consider a lower incidence of the receptor in advanced tumor stages.

Topics: Adolescent; Adult; Aged; Autocrine Communication; Carcinoma, Medullary; Cholecystokinin; Female; Gastrins; Humans; Immunohistochemistry; Male; Middle Aged; Mutation; Oncogenes; Pentagastrin; Receptor, Cholecystokinin B; Receptors, Cholecystokinin; Reverse Transcriptase Polymerase Chain Reaction; Stimulation, Chemical; Thyroid Gland; Thyroid Neoplasms

To characterize the influence of six factors on human thyroid tissues at the cell-proliferation level. These six factors were the epidermal growth factor (EGF), the luteinizing-hormone-releasing hormone (LHRH), triiodothyronine, thyroxine, estradiol and gastrin.. Forty-eight human thyroid specimens were obtained from surgical resection and maintained alive for 48 h ex vivo (in vitro) under organotypic culture conditions. These specimens comprised 35 benign cases (17 multinodular goiters and 18 adenomas) and 13 cancers. Cell proliferation in the control and treated conditions (at a 5 nM dose) was assessed by means of the thymidine labeling index, which enables the percentage of cells in the S phase of the cell cycle to be determined in accordance with autoradiographic procedures.. The results show that, of the six factors tested here, EGF significantly (P < 0.05 to P < 0.001) increased cell proliferation in the greatest number of cancers as compared to what happened with the remaining five. Each of these six factors significantly increased or decreased proliferative cell activity in some 10%-30% of the cases under study.. Triiodothyronine, thyroxine, LHRH and gastrin may increase or decrease cell proliferation in human thyroid tissues, whether benign or malignant, to the same extent as other hormones and/or growth factors such as thyrotropin, EGF, insulin-like growth factor 1, transforming growth factor beta1 and estradiol the effects of which on thyroid cell proliferation are already well documented in the literature.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Cell Division; Epidermal Growth Factor; Estradiol; Female; Gastrins; Gonadotropin-Releasing Hormone; Hormones; Humans; Male; Middle Aged; Organ Culture Techniques; Retrospective Studies; Thyroid Diseases; Thyroid Neoplasms; Thyroxine; Triiodothyronine

The high sensitivity of pentagastrin stimulation in detecting primary or metastatic medullary thyroid cancer (MTC) suggests widespread expression of the corresponding receptor type on human MTC. Indeed, autoradiographic studies have demonstrated cholecystokinin (CCK)-B/gastrin receptors not only in more than 90% of MTCs but also in a high percentage of small cell lung cancers, some ovarian cancers, astrocytomas and potentially a variety of adenocarcinomas. The aim of this study was to systematically screen and optimize, in a preclinical model and a pilot clinical study, suitable radioligands for targeting CCK-B receptors in vivo.. A variety of CCK/gastrin-related peptides, all bearing the C-terminal CCK receptor-binding tetrapeptide sequence Trp-Met-Asp-PheNH2 or derivatives thereof, were studied. They were radioiodinated by the lodogen or Bolton-Hunter procedures. The peptides were members of the gastrin or CCK families, which differ by the intramolecular position of a tyrosyl moiety. Their stability and affinity were studied in vitro and in vivo; their biodistribution and therapeutic efficacy were tested in nude mice bearing subcutaneous human MTC xenografts. Diethylenetriamine pentaacetic acid (DTPA) derivatives of suitable peptides were synthesized successfully, and their preclinical and initial clinical evaluations were performed, labeled with 111In.. All members of the CCK or gastrin families were stable in serum (with half-lives of several hours at 37 degrees C); nevertheless, the stability of those peptides bearing N-terminal pGlu residues or D-amino acids was significantly higher. In accordance with their comparably low affinity, nonsulfated members of the CCK family showed fairly low uptake in the tumor and other CCK-B receptor-expressing tissues. Sulfated CCK derivatives performed significantly better but also displayed a comparably high uptake in normal CCK-A receptor-expressing tissues. This effect was probably due to their similar affinity for both CCK-A and CCK-B receptors. Best tumor uptake and tumor-to-nontumor ratios were obtained with members of the gastrin family because of their selectivity and affinity for the CCK-B receptor subtype. Pilot therapy experiments in MTC-bearing animals showed significant antitumor efficacy compared with untreated controls. DTPA derivatives of minigastrin were successfully developed. In a pilot clinical study, radioiodinated and 111In-labeled derivatives showed excellent targeting of physiological CCK-B receptor-expressing organs, as well as all known tumor sites.. CCK/gastrin analogs may be a useful new class of receptor-binding peptides for diagnosis and therapy of CCK-B receptor-expressing tumors, such as MTC or small cell lung cancer. Nonsulfated gastrin derivatives may be preferable because of their CCK-B receptor selectivity, hence lower accretion in normal CCK-A receptor-expressing organs.

Topics: Adult; Aged; Amino Acid Sequence; Animals; Carcinoma, Medullary; Carcinoma, Small Cell; Cholecystokinin; Data Interpretation, Statistical; Female; Gastrins; Humans; Indium Radioisotopes; Iodine Radioisotopes; Isotope Labeling; Lung Neoplasms; Lymphatic Metastasis; Male; Mice; Mice, Nude; Middle Aged; Molecular Sequence Data; Neoplasm Metastasis; Neoplasms, Experimental; Peptides; Radioisotopes; Radionuclide Imaging; Receptors, Cholecystokinin; Thyroid Neoplasms

The high sensitivity of pentagastrin stimulation in detecting primary or metastatic medullary thyroid cancer (MTC) suggests widespread expression of the corresponding receptor type on human MTC. Indeed, autoradiographic studies demonstrated cholecystokinin (CCK)-B/gastrin receptors not only in >90% of MTCs but in a high percentage of small cell lung cancers and potentially a variety of gastrointestinal adenocarcinomas. In a pilot study, we have demonstrated the feasibility of radiolabeled gastrin-I to target CCK-B receptor-expressing tissues in vivo in animals and patients (T. M. Behr et al., Eur. J. Nucl. Med., 25: 424-430, 1998). The aim of the present study was to systematically optimize, in a preclinical model, suitable radioligands for targeting CCK-B receptors in vivo. For this purpose, a variety of CCK/gastrin-related peptides, all having in common the COOH-terminal CCK-receptor binding tetrapeptide sequence Trp-Met-Asp-PheNH2 or derivatives thereof, were studied. They were radioiodinated by the Iodogen or Bolton-Hunter procedures. The peptides tested were members of the gastrin- or cholecystokinin families or possessed characteristics of both, which differ by the intramolecular position of a tyrosyl moiety (occurring in native or sulfated form). Their stability and affinity were studied in vitro and in vivo; their biodistribution and therapeutic efficacy were tested in nude mice bearing s.c. human MTC xenografts. Diethylene-triamine-pentaacetate derivatives of suitable peptides were synthesized, evaluated, and labeled with (111)In. All members of the CCK or gastrin family were stable in serum (with t(1/2)s of several hours at 37 degrees C); nevertheless, the stability of those peptides was highest that bore the NH2-terminal pGlu residues (e.g., big gastrin, gastrin-I, caerulein, and others) or D-amino acids. In accordance to their comparably low affinity, nonsulfated members of the CCK family showed fairly low uptake in the tumor and other CCK-B receptor-expressing tissues (e.g., the stomach). Sulfated CCK derivatives performed significantly better but additionally displayed a high uptake in normal, CCK-A receptor-expressing tissues (such as the liver/gallbladder, pancreas, and bowel). Best tumor uptake and tumor:nontumor ratios were obtained with members of the gastrin family, probably because of their selectivity and affinity for the CCK-B receptor subtype. Pilot therapy experiments in MTC bearing animals showed significant antitumor efficacy as

Topics: Amino Acid Sequence; Animals; Gastrins; Humans; Indium Radioisotopes; Iodine Radioisotopes; Isotope Labeling; Mice; Mice, Nude; Molecular Sequence Data; Receptors, Cholecystokinin; Thyroid Neoplasms; Tissue Distribution; Tumor Cells, Cultured

The outstanding sensitivity of pentagastrin in detecting the presence of primary, recurrent or metastatic medullary thyroid cancer (MTC) suggests widespread expression of the corresponding receptor type in human MTC. Indeed, recent autoradiographic studies have demonstrated the presence of cholecystokinin (CCK)-B (= gastrin) receptors not only in more than 90% of MTCs but also in a high percentage of small cell lung cancers, stromal ovarian cancers, astrocytomas and several other tumour types. The aim of this study was to evaluate whether radiolabelled gastrin may be suitable for targeting CCK-B receptor-expressing tumours in vivo. For this purpose, the biodistribution of the radioiodinated human heptadecapeptide gastrin-I was studied in nude mice bearing subcutaneous xenografts of the human MTC cell line, TT. Initial therapy experiments were undertaken. Finally, the biodistribution of iodine-131- labelled gastrin-I was studied in a patient with metastatic MTC. At a peptide amount of approximately 1 microg, maximum tumour uptake (8.9+/-2.9%ID/g) was observed in animals at 1 h post injection, with tumour-to-blood ratios as high as 6.3+/-1.9. Physiological CCK-B receptors in the stomach, gallbladder and pancreas of the mice were targeted as well. The major route of excretion was renal, but strong evidence for a biliary excretion pathway also exists. Pilot therapy studies with 131I-labelled gastrin showed significant anti-tumour efficacy as compared with untreated controls. In accordance with the preclinical data, good receptor targeting was observed in the tumour sites, stomach, gallbladder and pancreas of a patient with metastatic MTC. These data suggest that gastrin and its analogues may represent a useful new class of receptor binding peptides for diagnosis and therapy of a variety of tumour types, including MTC and small cell lung cancer. Future preclinical and clinical studies will address in more detail the molecular features that render CCK-B receptor binding agents potentially useful candidates for in vivo scintigraphy and radionuclide therapy.

Topics: Aged; Animals; Carcinoma, Medullary; Feasibility Studies; Gastrins; Humans; Iodine Radioisotopes; Male; Mice; Mice, Nude; Neoplasm Transplantation; Radioimmunodetection; Radioimmunotherapy; Receptors, Cholecystokinin; Thyroid Neoplasms; Tissue Distribution

Medullary thyroid carcinoma (MTC) occurs sporadically but may also be inherited as part of the multiple endocrine neoplasia (MEN) type 2 syndrome. Screening of the patients and first degree relatives annually with basal and provocative tests for serum immunoreactive calcitonin (CT) levels is essential and enables potentially curative disease. Pentagastrin and calcium are the usual provocative agents used worldwide. We used endogenous gastrin (GT) release achieved by omeprazole, 20 mg b.i.d., to stimulate CT in 9 MTC, in 3 MEN 2A family members, and in 50 healthy control subjects. A steady and significant increase both in GT and CT levels was achieved in 9 MTC patients and 3 of the 14 family members tested, whereas in healthy controls the CT increase stimulated by GT was insignificant. Preliminary results showed that this new, safe, cheap, and outpatient-basis test can be used in MTC diagnosis, follow-up, and screening.

Topics: Adult; Aged; Calcitonin; Carcinoma, Medullary; Female; Follow-Up Studies; Gastrins; Humans; Immunoradiometric Assay; Male; Middle Aged; Multiple Endocrine Neoplasia Type 2a; Omeprazole; Pentagastrin; Reference Values; Thyroid Neoplasms

Cholecystokinin (CCK)-A and CCK-B/gastrin receptors were evaluated with in vitro receptor autoradiography in 406 human tumors of various origins using a sulfated 125I-labeled CCK decapeptide analogue 125I-(D-Tyr-Gly, Nle28,3l)-CCK 26-33 and 125I-labeled Leu15-gastrin as radioligands. CCK-B/gastrin receptors were found frequently in medullary thyroid carcinomas (92%), in small cell lung cancers (57%), in astrocytomas (65%), and in stromal ovarian cancers (100%). They were found occasionally in gastroenteropancreatic tumors, breast, endometrial, and ovarian adenocarcinomas. They were either not expressed or rarely expressed in colorectal cancers, differentiated thyroid cancers, non-small cell lung cancers, meningiomas, neuroblastomas, schwannomas, glioblastomas, lymphomas, renal cell cancers, prostate carcinomas, and the remaining neuroendocrine tumors (i.e., pituitary adenomas, pheochromocytomas, paragangliomas, and parathyroid adenomas). CCK-A receptors were expressed rarely in tumors except in gastroenteropancreatic tumors (38%), meningiomas (30%), and some neuroblastomas (19%). The identified CCK-A and CCK-B receptors were specific and of high affinity in the subnanomolar range. The rank order of potency of various CCK analogues was: sulfated CCK-8 = L-364,718 >> nonsulfated CCK-8 = L-365,260 > or = gastrin for CCK-A receptors and sulfated CCK-8 > gastrin = nonsulfated CCK-8 > L-365,260 > L-364,718 for CCK-B receptors. CCK-B receptors could also be selectively and specifically labeled with a newly designed nonsulfated 125I-(D-Tyr-Gly, Nle28,31)-CCK 26-33. Gastrin mRNA measured by in situ hybridization was present in most CCK-B receptor-positive small cell lung cancers, breast tumors, and ovarian tumors, representing the molecular basis of a possible autocrine growth regulation of these tumors. Gastrin and CCK mRNAs were lacking in medullary thyroid cancers. Thus, these results may have pathogenic, diagnostic, differential diagnostic, and therapeutic implications.

Topics: Autoradiography; Breast Neoplasms; Carcinoma, Small Cell; Cholecystokinin; Female; Gastrins; Humans; Lung Neoplasms; Neoplasms; Neuroendocrine Tumors; Ovarian Neoplasms; Receptor, Cholecystokinin A; Receptor, Cholecystokinin B; Receptors, Cholecystokinin; Sincalide; Thyroid Neoplasms

The 2 gastrointestinal peptides cholecystokinin (CCK) and gastrin, which act through CCK-A receptors (having high affinity for CCK) or CCK-B/gastrin receptors (having high affinity for CCK and gastrin), are considered to be important tumor growth factors. We have evaluated CCK-A and CCK-B/gastrin receptors in 34 human thyroid cancers using in vitro receptor autoradiography with 2 different radioligands. We demonstrate high-affinity CCK-B/gastrin receptors in medullary thyroid carcinomas, present at very high incidence (92%) but the absence of these receptors in non-medullary thyroid carcinomas or in normal thyroid glands. CCK-B/gastrin receptors are therefore likely to be the molecular substrate for the pentagastrin-stimulation test, widely used in medullary thyroid carcinomas; moreover, they represent the targets for physiologically secreted gastrin or CCK which, as growth factors, may stimulate the growth of medullary thyroid carcinomas. Furthermore, these results have diagnostic as well as therapeutic implications: radiolabeled gastrin and CCK analogs may be used for scintigraphic tumor localization in vivo, whereas CCK-B-selective antagonists may be of therapeutic value.

Topics: Autoradiography; Carcinoma, Medullary; Cholecystokinin; Gastrins; Humans; Iodine Radioisotopes; Receptor, Cholecystokinin A; Receptor, Cholecystokinin B; Receptors, Cholecystokinin; Sincalide; Thyroid Neoplasms

Topics: Adenoma; Adrenal Gland Neoplasms; Adrenocortical Hyperfunction; Aged; Carcinoma; Carcinoma, Papillary; Female; Gastrins; Humans; Hypercalcemia; Hypothyroidism; Multiple Endocrine Neoplasia; Pituitary Neoplasms; Thyroid Neoplasms

The concentrations of immunoreactive (IR) corticotropin-releasing hormone (CRH) in 218 neuroendocrine tumors were determined by CRH radioimmunoassay. The tumors examined were 86 pancreatic endocrine tumors (PET), 22 neuroblastic tumors (NBT), 26 carcinoid tumors (CA), 24 pheochromocytomas (PHEO), 40 small cell lung carcinomas (SCLC) and 20 medullary thyroid carcinomas (MTC). IR-CRH was detectable in 21 neuroendocrine tumors (10 PET, four NBT, three CA, two PHEO and two SCLC) at levels of 10-2,700 ng/g wet weight (9.6%). The 21 patients with these CRH-producing tumors showed no clinical symptoms suggestive of Cushing's syndrome. The levels of plasma IR-CRH extracted by immunoaffinity chromatography were < 7.5 pg/ml in five normal subjects and a patient with a neuroblastic tumor containing 55 ng/g wet weight IR-CRH, but in a patient with a thymic carcinoid tumor containing 1,000 ng/g wet weight IR-CRH, the plasma level was elevated to 180 pg/ml. This patient did not have Cushing's syndrome nor an elevated plasma adrenocorticotropic hormone (ACTH) level. The concentrations of nine peptides (growth hormone-releasing hormone, somatostatin, ACTH, calcitonin, gastrin-releasing peptide, glucagon, vasoactive intestinal peptide, neuropeptide tyrosine and pancreatic polypeptide) were determined in extracts of the 21 IR-CRH-producing tumors. Some of these peptides were frequently found to be produced concomitantly with CRH. The results indicate IR-CRH to be produced by various neuroendocrine tumors, but Cushing's syndrome, due to the CRH, to be very rare. The results also show that CRH-producing tumors produce multiple hormones.

Topics: Adenoma, Islet Cell; Adrenal Gland Neoplasms; Adrenocorticotropic Hormone; Bombesin; Calcitonin; Carcinoid Tumor; Carcinoma, Small Cell; Chromatography, Gel; Corticotropin-Releasing Hormone; Gastrin-Releasing Peptide; Gastrins; Humans; Hypothalamus; Lung Neoplasms; Neoplasms; Neuroblastoma; Pancreatic Neoplasms; Peptides; Pheochromocytoma; Somatostatin; Thyroid Neoplasms; Vasoactive Intestinal Peptide

Gastrin, the primary hormonal mediator of postprandial gastric acid secretion, is produced from its precursor progastrin by a series of posttranslational processing reactions including dibasic residue cleavage and carboxyl-terminal alpha-amidation. Progastrin contains three dibasic cleavage signals, Arg57Arg58, Lys74Lys75, and Arg94Arg95, that appear to be cleaved differently in different tissues. Differential processing is a potential means by which the production of biologically active peptides may be regulated in a tissue-specific manner. To study these reactions further, we used the pZipNeo SV(X) retroviral vector to express human gastrin cDNA in a heterologous cell line (MTC 6-23) known to be capable of processing other peptide precursors. The psi 2 packaging cell line transfected with the gastrin cDNA-retroviral construct (pSVXgas) produced progastrin, but no substantial amounts of processed amidated gastrin were detected. amounts of processed amidated gastrin were detected. In contrast, MTC 6-23 cells infected with the viral stock obtained from the supernatant of pSVXgas-transfected psi 2 cells produced carboxyl-terminally amidated gastrin in all of its standard molecular forms, including sulfated and nonsulfated forms of tetratriacontagastrin (G-34), heptadecagastrin (G-17), and tetradecagastrin (G-14). These studies indicate that heterologous endocrine cell lines infected with a retroviral-peptide cDNA construct can serve as useful models for peptide hormone posttranslational processing.

Topics: Amino Acid Sequence; Animals; Cell Line; Chromatography, High Pressure Liquid; Gastrins; Gene Expression; Genetic Vectors; Humans; Immunoenzyme Techniques; Mice; Molecular Sequence Data; Plasmids; Poly A; Protein Precursors; Protein Processing, Post-Translational; Radioimmunoassay; Restriction Mapping; RNA; RNA, Messenger; Thyroid Neoplasms; Transfection

The expression of gastrin/cholecystokinin (CCK) peptides and their precursors was examined in 16 medullary carcinomas of the human thyroid. Measurements with libraries of sequence-specific radioimmunoassays before and after enzymatic cleavage of extracts and chromatographic fractions showed that the carcinomas contained 1.7 pmol carboxyamidated CCK/g tissue (median; range 0.6-21.8 pmol/g), 0.9 pmol glycine-extended precursor/g (median; range less than 0.2-2.3 pmol/g) and 2.3 pmol further COOH-terminal-extended proCCK/g (median; range 0.9-6.2 pmol/g). Neither carboxyamidated gastrins nor any progastrins could be measured. Gel and reverse-phase chromatography revealed only small molecular forms, i.e. greater than 90% of the amidated immunoreactivity eluted like non-sulphated CCK-8 or CCK-7. The results show that human medullary thyroid carcinomas synthesize CCK peptides. The predominance of non-sulphated CCK is unusual. Taken together with earlier observations from dogs and pigs, our results raise the possibility that small non-sulphated CCK peptides modulate thyroid C-cell secretion in an autocrine manner.

Topics: Amino Acid Sequence; Carcinoma; Cholecystokinin; Chromatography, Gel; Chromatography, High Pressure Liquid; Gastrins; Humans; Molecular Sequence Data; Peptide Fragments; Protein Precursors; Radioimmunoassay; Thyroid Neoplasms

A 43 year old man is presented who suffered from the association of a toxic adenoma of the thyroid gland and a Zollinger-Ellison syndrome (ZES) due to a metastasizing duodenal gastrinoma. There were no other signs of a multiple endocrine neoplasia syndrome, type I (MEN-I). The patient presented here shows that the association of ZES and thyroid disease may also occur in patients with sporadic ZES.

Topics: Adenoma; Adult; Duodenal Neoplasms; Gastrectomy; Gastrinoma; Gastrins; Humans; Hyperthyroidism; Immunohistochemistry; Male; Thyroid Neoplasms; Zollinger-Ellison Syndrome

Thirty-three patients with advanced, metastatic APUD tumors (islet cell, carcinoid, or medullary carcinomas of the thyroid) were treated with etoposide as a single agent. Of 29 evaluable patients, four (14%) had partial responses (95% confidence limits, 1%-26%). Toxic effects seen were those previously reported for etoposide as a single agent. Etoposide has activity in APUD tumors; further studies with this agent are indicated.

Topics: Adenoma, Islet Cell; Adult; Aged; Calcitonin; Carcinoembryonic Antigen; Carcinoid Tumor; Drug Evaluation; Etoposide; Female; Gastrins; Humans; Hydroxyindoleacetic Acid; Male; Middle Aged; Thyroid Neoplasms

Human gastrin-releasing peptide (GRP) mRNA was detected in the tumor tissues of medullary thyroid carcinomas and small cell lung carcinomas using synthetic oligodeoxyribonucleotides as hybridization probes. The amount of GRP mRNA was estimated by radiodensitometric hybridization assay. A good correlation was found between the amount of GRP mRNA and the concentration of immunoreactive GRP in the tumor tissues.

Topics: Carcinoma; Carcinoma, Small Cell; Densitometry; Gastrin-Releasing Peptide; Gastrins; Humans; Immunologic Techniques; Lung Neoplasms; Nucleic Acid Hybridization; Oligodeoxyribonucleotides; Peptides; Radioimmunoassay; RNA, Messenger; Thyroid Neoplasms

A somatostatin analog (SMS 201-995) was used to treat symptomatic patients with a residual tumor burden of gastrinoma or medullary thyroid carcinoma and pathologic elevations of circulating marker peptides associated with these neuroendocrine tumors. Possible inhibitory effects of the analog on marker peptides, patients' symptoms, or tumor progression were studied in a dose-response protocol and during several months of self-injection of SMS 201-995. Both patients reported remarkable relief of secretory diarrhea and other symptoms, and serum gastrin was successfully suppressed by increasing doses of the analog. However, no effect was seen in reduction of hypercalcitoninemia. Morphologic imaging of residual tumor showed no progression of medullary thyroid carcinoma during treatment and, in the case of hepatic gastrinoma metastases, remarkable tumor regression was confirmed. No toxicity or glucose intolerance was experienced. Somatostatin analog shows promise for palliative management of endocrinologic symptoms due to neuroendocrine tumors, and an inhibitory effect can be measured in some but not all peptide markers. Further evidence of its negative trophic effect on tumor blood flow may suggest an antineoplastic potential, as well as palliative use of this new treatment.

Topics: Adult; Antineoplastic Agents; Calcitonin; Carcinoma; Dose-Response Relationship, Drug; Drug Evaluation; Female; Gastrins; Humans; Male; Octreotide; Palliative Care; Postoperative Care; Somatostatin; Thyroid Neoplasms; Zollinger-Ellison Syndrome

The effects of synthetic [Asu1,7]-eel calcitonin (0.5 MRC unit/kg body weight intravenously for 30 min) on circulating levels of human calcitonin, calcium and gastrin were investigated in five patients with medullary carcinoma of the thyroid. Blood samples were obtained before and 15, 30, 60, 90, 120 and 180 min after commencement of infusion of [Asu1,7]-eel calcitonin. Plasma levels of human calcitonin were measured by radioimmunoassay. Cross-reactivity with [Asu1,7]-eel calcitonin in this assay was negligible. On infusion of [Asu1,7]-eel calcitonin, the mean plasma level of human calcitonin decreased significantly to 71.0 +/- 8.7% of the basal level (mean +/- SEM, P less than 0.05) after 30 min and 68.4 +/- 25.4% of the basal level (P less than 0.05) after 60 min. The serum calcium level also decreased significantly, but lagged behind the decrease of human calcitonin, being 95.1 +/- 0.7% of the basal level (P less than 0.01) at 120 min and 94.8 +/- 0.6% of the basal level (P less than 0.02) at 180 min. The mean plasma gastrin level did not change significantly on infusion of [Asu1,7]-eel calcitonin. In pooled data for all times, the percentage change in human calcitonin was not significantly correlated with either the percentage change in calcium (r = -0.25, P greater than 0.1) or the percentage change in gastrin (r = -0.38, P greater than 0.1).

Topics: Adolescent; Adult; Aged; Animals; Calcitonin; Calcium; Carcinoma; Eels; Female; Gastrins; Humans; Male; Thyroid Neoplasms

Twenty medullary carcinomas of the thyroid gland were examined for the presence of immunoreactive calcitonin, thyroglobulin, glucagon, keratin, gastrin/CCK, carcinoembryonic antibody (CEA), insulin, serotonin, adreno-corticotropic hormone (ACTH), prostatic acid phosphatase, and somatostatin using the immunoperoxidase peroxidase-antiperoxidase technique. In addition, they were stained with mucicarmine, alcian blue/periodic acid-Schiff (PAS), Grimelius, Congo red, crystal violet, and Fontana-Masson stains. Calcitonin-immunoreactive cells were absent in one tumor and present in 19 tumors (95%). Thyroglobulin was present in seven tumors (35%). Twenty tumors contained CEA-immunoreactive cells (100%). Fourteen cases were immunoreactive to serotonin (70%) and 12 were positive for somatostatin (60%). Glucagon- and gastrin/CCK-immunoreactive cells were found in two cases each (10%). Four tumors (20%) contained ACTH-immunoreactive cells and three cases (15%) were positive for prostatic acid phosphatase. Five cases (25%) contained keratin-immunoreactive cells. One case was immunoreactive to insulin (5%). Grimelius-positive cells were present in 19 of the cases (95%). Mucin-containing cells were present in 65% of the cases. The validity of the immunocytochemical localizations was tested by specific absorption of each antibody with the corresponding antigen. The demonstration of immunoreactivity for multiple antigens in each of the 20 cases suggests that the origin of medullary thyroid carcinomas is from a neuroendocrine cell potentially capable of producing numerous hormone substances. In addition, as the neoplastic cells in 35% of the tumors contained hormonal substances as well as thyroglobulin, it is suggested that papillary or follicular tumors mixed with a neuroendocrine component exist more commonly than previously suspected. Finally, psammoma bodies might be present in pure medullary carcinoma of the thyroid gland.

Topics: Acid Phosphatase; Adrenocorticotropic Hormone; Aged; Calcitonin; Carcinoembryonic Antigen; Carcinoma; Female; Gastrins; Glucagon; Humans; Lymphatic Metastasis; Male; Middle Aged; Mitosis; Serotonin; Somatostatin; Staining and Labeling; Thyroglobulin; Thyroid Neoplasms

Results of preparathyroidectomy and postparathyroidectomy studies in a patient with multiple endocrine neoplasia type I and gastrinoma suggest that hyperparathyroidism unmasks occult gastrinoma and related secretory abnormalities. Three of four diagnostic findings were later obscured by parathyroidectomy and normalization of serum calcium concentration. Basal acid output, basal acid output/maximal acid output ratio, and serum gastrin concentration were decreased from values consistent with gastrinoma to normal. The secretin stimulation test, though still positive, was attenuated. These observations suggest that in multiple endocrine neoplasia type I, normal values for serum gastrin concentration, gastric secretion, and secretin stimulation may not exclude gastrinoma. The investigations clarify the interpretation of a voluminous but confusing literature on the interrelationship between hyperparathyroidism and altered gastric function in the presence or absence of Zollinger-Ellison syndrome.

Topics: Adenoma; Adult; Calcium; Drug Interactions; Female; Gastric Acid; Gastrins; Humans; Hyperparathyroidism; Multiple Endocrine Neoplasia; Parathyroid Hormone; Pituitary Neoplasms; Secretin; Thyroid Neoplasms; Zollinger-Ellison Syndrome

Neuroendocrine tumours of the lung and gut are known to possess bombesin-like immunoreactivity. The recent observation that gastrin releasing peptide (GRP), a 27 amino acid peptide isolated from the porcine intestine, may be the mammalian analogue of bombesin led us to look for this peptide in a variety of human neoplasms. Formalin-fixed tissues from 85 tumours were examined by the immunoperoxidase technique, using specific antisera to the GRP molecule (1-27) and the GRP fragment (1-16). Intense cytoplasmic GRP immunoreactivity was seen in thyroid medullary carcinomas (3/3), carcinoids of lung, pancreas, and intestine (22/36), and paragangliomas (2/3). Less frequent staining was present in pulmonary small cell (oat cell) carcinomas (1/8) and pituitary adenomas (1/6). Complete absence of immunoreactivity was observed in three phaeochromocytomas, five Merkel cell tumours, six neuroblastomas and 15 non-neuroendocrine tumours. Normal neuroendocrine cells of the thyroid (C-cells) and bronchial mucosa (Kulchitsky cells) exhibited GRP immunoreactivity; nerve fibres from all sites failed to demonstrate staining for GRP. In each positive case, the pattern of staining for GRP (1-27) and GRP (1-16) was identical, although the GRP (1-16) immunostaining was weaker. These findings indicate that bombesin immunoreactivity in human neuroendocrine cells and tumours is attributable to GRP-like molecules and that GRP is a useful marker of neuroendocrine differentiation in many tumours.

Topics: Adenoma; Adrenal Gland Neoplasms; Amino Acid Sequence; Bombesin; Carcinoid Tumor; Carcinoma, Small Cell; Gastrin-Releasing Peptide; Gastrins; Humans; Intestinal Neoplasms; Lung Neoplasms; Neoplasms; Neurosecretory Systems; Pancreatic Neoplasms; Peptides; Pheochromocytoma; Pituitary Neoplasms; Thyroid Neoplasms

Gastrin-releasing peptide, the mammalian counterpart of amphibian bombesin, has been found to be present in high concentration by radioimmunoassay in eight histologically confirmed medullary thyroid carcinomas and to be undetectable in postmortem normal thyroid tissue. Chromatographic analysis of the tumor extracts by gel permeation revealed two major peaks of gastrin-releasing peptide-like immunoreactivity (GRP-LI). However, reverse-phase high-pressure liquid chromatography demonstrated three immunoreactive peaks of GRP-LI. None of these immunoreactive peaks was coeluted with synthetic porcine GRP or amphibian bombesin, but one of the peaks exactly emerged in the position of neuromedin C (C-terminal decapeptide of GRP). Sections from nine primary or secondary tumours were immunostained for GRP using a peroxidase/anti-peroxidase technic. All the medullary thyroid carcinomas were shown to contain GRP-LI, specifically localized to the tumor cells. This immunoreactivity is elevated in plasma from some patients with this malignancy, raising the possibility that it may be used as an additional tumor marker.

Topics: Carcinoma; Chromatography, Gel; Chromatography, High Pressure Liquid; Gastrin-Releasing Peptide; Gastrins; Humans; Immunochemistry; Peptides; Radioimmunoassay; Thyroid Gland; Thyroid Neoplasms

In 12 patients treated 2 to 58 months previously for medullary carcinoma of the thyroid, basal serum concentrations of calcitonin, gastrin, vasoactive intestinal polypeptide, glucagon, insulin, and pancreatic polypeptide were measured in search of any correlation between these and the clinical course of the disease. All patients had elevated serum calcitonin levels indicating present disease. One patient had increased serum concentrations of several hormones. Another had achlorhydria and high serum gastrin levels. No relationship between calcitonin and gastro-intestinal polypeptides was found in 11 patients. No correlations were found between serum levels of polypeptides and the occurrence of diarrhoea in 5 patients. It is concluded that gastro-intestinal polypeptides, which are produced by other apudomas, are not secreted in more than normal concentrations under basal conditions, by the majority of patients previously treated for medullary carcinoma of the thyroid.

Topics: Adolescent; Adult; Aged; Calcitonin; Carcinoma; Diarrhea; Female; Gastric Inhibitory Polypeptide; Gastrins; Gastrointestinal Hormones; Glucagon; Humans; Insulin; Male; Middle Aged; Thyroid Neoplasms; Vasoactive Intestinal Peptide

The serum gastrin response to a standard test meal was evaluated in patients with familial medullary thyroid carcinoma (MTC) and in normal subjects. Patients with MTC and elevated plasma calcitonin levels had a lower gastrin response to the test meal than did normal persons or MTC patients who had normal calcitonin levels postthyroidectomy. There was no significant difference between the mean gastrin response of the normal group and that of the MTC patients with normal calcitonin levels. The serum gastrin response was studied before and after thyroidectomy in four patients. In all four, the post-operative response was greater than the preoperative one . We conclude that patients with MTC may have reduced gastrin responses to a test meal. This effect may be related to circulating calcitonin, somatostatin, or other factors related to familial MTC.

Topics: Adolescent; Adult; Calcitonin; Child; Female; Food; Gastrins; Humans; Male; Middle Aged; Thyroid Neoplasms; Thyroidectomy

Rats transplanted with medullary thyroid carcinoma (MTC) were divided into 3 groups which received for 34 weeks diets with low (0.09%), medium (0.40%) or high (1.80%) calcium content with a calcium/phosphate ratio 2:1. After 6 weeks the different calcium regimens produced corresponding variations in serum calcium and inverse changes in serum magnesium. No alterations in serum proteins were observed. Serum immunoreactive calcitonin (iCT) was unaltered until week 28 of the experiment, but thereafter increased rapidly by about 4-fold. No difference in serum iCT was observed between the 3 groups at any time. Immunoreactive serum gastrin was reduced in rats on medium and low calcium diet compared to those on a high calcium diet. After 28 weeks, when serum iCT was rising, gastrin values fell in rats on high calcium diet to levels approaching those in the other groups. With increased serum iCT (weeks 28-34) serum gastrin concentrations were low and equal in the 3 groups despite different serum calcium concentrations. Electronmicroscopic examination of tumors from the various diet groups did not reveal significant ultrastructural differences.. low, medium and high calcium intake gave corresponding changes in serum calcium. Diet-induced hypercalcaemia was not normalized by elevated serum iCT. In contrast, serum immunoreactive gastrin maintained by high calcium diet was suppressed by hypercalcitonaemia.

Topics: Animals; Calcitonin; Calcium; Calcium, Dietary; Carcinoma; Cytoplasmic Granules; Female; Gastrins; Neoplasm Transplantation; Neoplasms, Experimental; Rats; Thyroid Neoplasms

In 3 patients with medullary thyroid carcinoma, plasma calcitonin levels showed 3 distinct peaks associated with a simultaneous rise in plasma gastrin after each meal. It is suggested that endogenous gastrin secreted following food intake stimulated the calcitonin secretion from the tumor. The peak of the plasma calcitonin secretion after the evening meal was less prominent than that for breakfast or lunch, while no significant differences were observed in peak values in plasma gastrin after each meal. The reason for this discrepancy remains to be clarified.

Topics: Adult; Aged; Calcitonin; Carcinoma; Circadian Rhythm; Eating; Female; Gastrins; Humans; Thyroid Neoplasms

Rats transplanted with medullary thyroid carcinoma (MCT) were followed with radio-immuno assay of serum calcitonin (iCT) using antisera to human CT and I125 labelled calcitonin-M. From the 4th month after transplantation, serum from the tumour rats contained iCT in concentrations 8-10 fold higher than serum from the control rats. The tumour cells had retained their ability to react on pentagastrin and calcium injections with increased CT release. It was further shown that the tumour bearing rats had elevated basal gastrin concentratkons in serum. While calcium injection lead to a rise in the serum gastrin concentration in the control group, the adverse effect was seen in the tumour bearing rats. The morphological features and the responsiveness of the rat tumour cells to physiological secretagogues make this tumour a suitable animal model for the study of interactions between CT and gastro-intestinal factors. It is suggested that the gastrin response to calcium might be of interest also in the diagnosis of human MCT.

Topics: Animals; Calcitonin; Calcium; Carcinoma; Female; Gastric Juice; Gastrins; Neoplasm Transplantation; Neoplasms, Experimental; Pentagastrin; Rats; Secretory Rate; Thyroid Neoplasms; Time Factors

The role of prostaglandins in endocrine diarrheagenic syndromes was evaluated by measuring peripheral concentration of immunoreactive PGE and PGF in patients with non-endocrine diarrhea as well as those with the Zollinger-Ellison (Z-E) syndrome, MCT, carcinoid tumors and the WDHA syndrome. In 21 normals, PGE and PGF levels averaged 272 +/- 18 and 119 +/- 14 pg/ml, respectively. Twenty eight patients with diarrhea of non-endocrine origin (mainly inflammatory bowel disease) had levels indistinguishable from normal, i.e. 353 +/- 25 and 77 +/- 37 pg/ml, respectively. Among 29 patients with the Zollinger-Ellison syndrome (mean gastrin 6127 +/- 3267 pg/ml) only 2 had significantly elevated PGE levels; mean PGE levels, 382 +/- 32 pg/ml, were not significantly different from normal and did not correlate with either diarrhea or the serum gastrin concentration. In contrast, 18 of 22 patients with carcinoid tumors (mean blood serotonin concentration 1655 +/- 604 ng/ml; mean urinary excretion of 5 HIAA 66.8 +/- 16.7 mg/day) had elevated peripheral concentrations of PGE. The mean PGE level (1367 +/- 245 pg/ml) was significantly elevated (P less than 0.001). Nonetheless PGE levels did not correlate with diarrhea, blood concentrations of serotonin, or urinary indole excretion. MCT (mean serum calcitonin 24.5 +/- 6.3 ng/ml) was similarly associated with consistent (18/19) elevation in peripheral concentrations of PGE (mean 1922 +/- 541 pg/ml; P less than 0.001). Inthis syndrome, PGE levels were higher in patients with diarrhea and in those with markedly elevated serum thyrocalcitonin levels. Finally, 8 of 21 patients with the WDHA syndrome had increased levels of PGE. Although 13 of 17 patients had high levels of VIP (mean 8133 pg/ml), 2 patients had hyperprostaglandinemia in the face of normal peripheral concentrations of VIP. In one patient the serum PGE level was elevated prior to resection of the primary pancreatic neoplasm (9939 pg/ml) as well as the subsequent extirpation of a solitary hepatic metastasis (1063 pg/ml); following each procedure the diarrhea abated and the PGE level returned to normal. In none of these syndromes were mean PGF levels elevated. The study has documented hyperprostaglandinemia in some endocrine diarrheagenic syndromes and validated the usefullness of measurements of PGE in patients with unexplained diarrhea.

Topics: Adenoma, Islet Cell; Adolescent; Adult; Aged; Diarrhea; Female; Gastrins; Humans; Male; Middle Aged; Prostaglandins E; Prostaglandins F; Thyroid Neoplasms; Zollinger-Ellison Syndrome

Plasma hCT levels were less than 50 pg/ml in 50 normal subjects. In 16 patients with medullary carcinoma of the thyroid (MCT), plasma hCT levels were distinctively elevated and they fell significantly after total thyroidectomy, but in 11 of them plasma levels were still high, indicating the presence of metastases. In 74 patients with the other types of malignancy, plasma hCT levels were found to be high in 9 cases (3 oat cell carcinoma of the lung, 4 malignant carcinoids, one malignant pheochromocytoma and one acute myelocytic leukemia). Except for the leukemic case, all these tumors were derived from neural crest. In 12 patients with primary hyperparathyroidism, plasma hCT levels were less than 20 pg/ml. In 13 hypoparathyroid patients, two with pseudohypoparathyroidism and one with pseudoidiopathic hypoparathyroidism, plasma hCT levels were slightly elevated. Some patients with uremia had elevated plasma hCT levels, but there was no relation between plasma levels of hCT and those of PTH, urea nitrogen or creatinine. In response to Ca (4.5 mg/kg/10 min) or tetragastrin (4 mug/kg/5 min) infusion, a marked increase in plasma hCT was observed in all patients with MCT, but not in normal subjects. In 5 hypoparathyroid patients, a significant increase to both stimuli was also observed in all cases. Two patients with pseudopseudohypoparathyroidism responded to the Ca load. These results indicate that the determination of plasma hCT levels especially after a short Ca or tetragastrin infusion is important to study various pathological conditions.

Topics: Calcitonin; Calcium; Carcinoma; Carcinoma, Small Cell; Cross Reactions; Dose-Response Relationship, Drug; Gastrins; Humans; Hyperparathyroidism; Infusions, Parenteral; Lung Neoplasms; Thyroid Neoplasms; Thyroidectomy

We have compared the effects of oral and intravenous ethanol on the secretion of both thyrocalcitonin and gastrin in five patients with medullary carcinoma of the thyroid. Ethanol caused a moderate rise in plasma thyrocalcitonin to 316% +/- 343% of baseline when given intravenously and to 197% +/- 106% of baseline when given orally. Only oral ethanol caused a measurable rise in serum gastrin levels. Serum calcium did not change significantly from baseline during either oral or intravenous administration. The results suggest that stimulation of thyrocalcitonin secretion by ethanol is not secondary to increased secretion of gastrin nor to the induction of hypercalcemia. Neither oral nor intravenous ethanol appears to be as effective as intravenous pentagastrin in testing for the presence of medullary carcinoma.

Topics: Administration, Oral; Calcitonin; Carcinoma; Ethanol; Female; Gastrins; Humans; Injections, Intravenous; Male; Middle Aged; Pentagastrin; Thyroid Gland; Thyroid Neoplasms

Topics: Adenoma, Islet Cell; Calcium; Endocrine Glands; Gastric Acidity Determination; Gastrins; Humans; Hyperparathyroidism, Secondary; Pancreatic Neoplasms; Secretory Rate; Thyroid Neoplasms; Zollinger-Ellison Syndrome

Topics: Adolescent; Adult; Aged; Animals; Calcitonin; Carcinoma; Chickens; Depression, Chemical; Female; Gastrins; Guinea Pigs; Humans; Immune Sera; Iodine Isotopes; Male; Middle Aged; Radioimmunoassay; Stimulation, Chemical; Thyroid Neoplasms; Zollinger-Ellison Syndrome

Topics: Aged; Animals; Antigen-Antibody Reactions; Calcitonin; Depression, Chemical; Female; Gastrins; Humans; Injections, Intravenous; Male; Middle Aged; Swine; Thyroid Neoplasms

Topics: Adenoma, Islet Cell; Adrenal Gland Neoplasms; Adult; Aged; Biopsy; Carcinoid Tumor; Female; Gastric Mucosa; Gastrins; Humans; Hyperplasia; Male; Microscopy, Electron; Middle Aged; Pedigree; Pituitary Neoplasms; Prospective Studies; Pyloric Antrum; Thyroid Neoplasms; Zollinger-Ellison Syndrome

Topics: Adenoma, Islet Cell; Adrenal Gland Neoplasms; Adult; Aged; Biological Assay; Female; Gastrectomy; Gastric Acidity Determination; Gastrins; Humans; Hyperinsulinism; Hyperparathyroidism; Male; Middle Aged; Multiple Endocrine Neoplasia; Peptic Ulcer; Pituitary Neoplasms; Radiography; Thyroid Neoplasms; Zollinger-Ellison Syndrome