RESUMO
Peptide receptor radionuclide therapy (PRRNT) is a molecularly targeted radiation therapy involving the systemic administration of a radiolabelled peptide designed to target with high affinity and specificity receptors overexpressed on tumours. PRRNT employing the radiotagged somatostatin receptor agonists (90)Y-DOTATOC ([(90)Y-DOTA(0),Tyr(3)]-octreotide) or (177)Lu-DOTATATE ([(177)Lu-DOTA(0),Tyr(3),Thr(8)]-octreotide or [(177)Lu-DOTA(0),Tyr(3)]-octreotate) have been successfully used for the past 15 years to target metastatic or inoperable neuroendocrine tumours expressing the somatostatin receptor subtype 2. Accumulated evidence from clinical experience indicates that these tumours can be subjected to a high absorbed dose which leads to partial or complete objective responses in up to 30 % of treated patients. Survival analyses indicate that patients presenting with high tumour receptor expression at study entry and receiving (177)Lu-DOTATATE or (90)Y-DOTATOC treatment show significantly higher objective responses, leading to longer survival and improved quality of life. Side effects of PRRNT are typically seen in the kidneys and bone marrow. These, however, are usually mild provided adequate protective measures are undertaken. Despite the large body of evidence regarding efficacy and clinical safety, PRRNT is still considered an investigational treatment and its implementation must comply with national legislation, and ethical guidelines concerning human therapeutic investigations. This guidance was formulated based on recent literature and leading experts' opinions. It covers the rationale, indications and contraindications for PRRNT, assessment of treatment response and patient follow-up. This document is aimed at guiding nuclear medicine specialists in selecting likely candidates to receive PRRNT and to deliver the treatment in a safe and effective manner. This document is largely based on the book published through a joint international effort under the auspices of the Nuclear Medicine Section of the International Atomic Energy Agency.
Assuntos
Agências Internacionais , Terapia de Alvo Molecular/métodos , Tumores Neuroendócrinos/radioterapia , Energia Nuclear , Radioterapia/métodos , Receptores de Peptídeos/metabolismo , Sociedades Científicas , Europa (Continente) , Seguimentos , Humanos , Rim/fisiologia , Rim/efeitos da radiação , Terapia de Alvo Molecular/efeitos adversos , Tumores Neuroendócrinos/metabolismo , Controle de Qualidade , Radiometria , Compostos Radiofarmacêuticos/efeitos adversos , Compostos Radiofarmacêuticos/uso terapêutico , Radioterapia/efeitos adversosRESUMO
PURPOSE: Somatostatin (SST) analogues have been used to treat proliferative diabetic retinopathy, pseudotumor cerebri, thyroid orbitopathy, and cystoid macular edema. There is a paucity of published data in regards to cell-specific distribution of SST receptors (SSTR) in normal human eye tissues. Gene expression for all five known SSTRs in normal human ciliary body/iris, retina, choroid, and cultured retinal pigment epithelial (RPE) cells were studied. METHODS: mRNA was isolated from human ocular tissues (iris/ciliary body, retina, and choroid) dissected from eight pairs of normal eyes (9-62 years) and from RPE cells grown in culture. RT-PCR was done for all five SSTRs in all analyzed tissues. Immunohistochemistry for SSTR1 and SSTR2 was performed on eight pairs of normal human eyes (28-74 years) imbedded in paraffin. RESULTS: SSTR1 to 5 genes are expressed in retina, SSTR1 and SSTR2 genes in cultured RPE cells, and SSTR1, 2, and 4 in ciliary body and choroid. SSTR1 and SSTR2 immunoreactivity (-ir) was observed on a variety of cells within all analyzed tissues including cornea, iris, trabecular meshwork, Schlemm's canal, ciliary processes, ciliary muscle, retina, choroid, cultured RPE cells, and optic nerve. CONCLUSIONS: SSTR genes are widely expressed in normal human eye tissues, with genes for SSTR1 and SSTR2 being the most widely expressed. Genes for all SSTRs are expressed in retina. SSTR1-ir and SSTR2-ir were observed in all analyzed ocular tissues. Detailed knowledge of SSTRs distribution and function in the human eye will result in a better understanding of their role in health and disease.
Assuntos
Olho/metabolismo , Expressão Gênica , RNA Mensageiro/metabolismo , Receptores de Somatostatina/genética , Adolescente , Adulto , Idoso , Células Cultivadas , Criança , Corioide/metabolismo , Corpo Ciliar/metabolismo , Primers do DNA/química , Técnica Indireta de Fluorescência para Anticorpo , Humanos , Técnicas Imunoenzimáticas , Iris/metabolismo , Pessoa de Meia-Idade , Epitélio Pigmentado Ocular/metabolismo , Receptores de Somatostatina/metabolismo , Retina/metabolismoRESUMO
We hypothesized that non-proliferating (quiescent) human vascular endothelial cells would not express somatostatin receptor subtype 2 (sst 2) and that this receptor would be expressed when the endothelial cells begin to grow. To test this hypothesis, placental veins were harvested from 6 human placentas and 2 mm vein disks were cultured in 0.3% fibrin gels. Morphometric analysis confirmed that 50-75% of cultured vein disks developed radial capillary growth within 15 days. Sst 2 gene expression was determined by reverse transcription-polymerase chain reaction (RT-PCR) analysis of the RNA from veins before culture and from tissue-matched vein disks that exhibited an angiogenic response. The sst 2 gene was expressed in the proliferating angiogenic sprouts of human vascular endothelium. The presence of sst 2 receptors on proliferating angiogenic vessels was confirmed by immunohistochemical staining and in vivo scintigraphy. These results suggest that sst 2 may be a unique target for antiangiogenic therapy with sst 2 preferring somatostatin analogues conjugated to radioisotopes or cytotoxic agents.
Assuntos
Endotélio Vascular/metabolismo , Receptores de Somatostatina/metabolismo , Animais , Sequência de Bases , Células Cultivadas , Técnicas de Cultura , Primers do DNA , Endotélio Vascular/citologia , Expressão Gênica , Humanos , Imuno-Histoquímica , Camundongos , Camundongos Nus , Neovascularização Fisiológica , Receptores de Somatostatina/genética , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
INTRODUCTION: Neuroendocrine tumors often metastasize to the liver and present with disabling hormonal symptoms. Hepatic artery chemoembolization (HACE) combined with somatostatin therapy, pre-embolization, peri-embolization and post-embolization, at doses to control symptoms, is an aggressive approach that can relieve hormonal symptoms with minimal morbidity and mortality. METHODS: Chemoembolization was performed using 30 mg of adriamycin, 50 mg of mitomycin, 12 ml of hexabrix, 10 ml of ethiodol, and 360-500-microm particles. Pancreastatin, a split product of chromogranin A, was measured pre-HACE and post-HACE in all patients. RESULTS: Forty-three chemoebolization procedures were performed in 34 symptomatic patients from December 1995 to August 1999. Seventeen patients had intestinal primaries (50%), seven had pancreatic primaries (20%), five had bronchial primaries (15%), and five had unknown primaries (15%). Systemic pancreastatin levels were improved or stable in 31 patients (78%). Symptoms were improved in these 31 patients (78%). Systemic serotonin levels were improved or stable in 24 patients (60%). Radiographic improvement or stability was seen in 18 patients (45%). Procedural related morbidity included pain, fevers, nausea, vomiting, and transient elevations of liver function studies in 75-100% of patients. There was one procedural related mortality (2%). Less than 20% improvement in pancreastatin levels from baseline was associated with death in five of five patients (100%). This was not observed with serotonin levels. CONCLUSION: Measurement of serum pancreastatin levels is an easy and useful method to predict success in patients who undergo HACE plus somatostatin therapy for metastatic neuroendocrine tumors to the liver. This therapeutic approach is effective in relieving symptoms in 78% of patients, with minimal major morbidity or mortality.
Assuntos
Quimioembolização Terapêutica , Artéria Hepática , Tumores Neuroendócrinos/sangue , Tumores Neuroendócrinos/terapia , Hormônios Pancreáticos/sangue , Somatostatina/análogos & derivados , Somatostatina/uso terapêutico , Adulto , Idoso , Idoso de 80 Anos ou mais , Antineoplásicos/administração & dosagem , Antineoplásicos/farmacologia , Biomarcadores Tumorais/sangue , Biomarcadores Tumorais/metabolismo , Quimioembolização Terapêutica/efeitos adversos , Cromogranina A , Cromograninas/sangue , Cromograninas/metabolismo , Meios de Contraste/administração & dosagem , Doxorrubicina/administração & dosagem , Doxorrubicina/farmacologia , Óleo Etiodado/administração & dosagem , Feminino , Seguimentos , Humanos , Ácido Ioxáglico/administração & dosagem , Neoplasias Hepáticas/sangue , Neoplasias Hepáticas/mortalidade , Neoplasias Hepáticas/secundário , Neoplasias Hepáticas/terapia , Masculino , Pessoa de Meia-Idade , Mitomicina/administração & dosagem , Mitomicina/farmacologia , Tumores Neuroendócrinos/mortalidade , Tumores Neuroendócrinos/patologia , Hormônios Pancreáticos/metabolismo , Serotonina/sangueRESUMO
Somatostatin receptor expression is a favorable prognostic factor in human neuroblastoma. Somatostatin receptors have been demonstrated in vitro by pharmacologic analysis of tumor tissue and in vivo by diagnostic radioreceptor scintigraphy. However, which receptor subtypes (sst(1), sst(2), sst(3), sst(4), and sst(5)) are expressed in these tumors has not yet been delineated. We used RT-PCR to analyze expression of the five somatostatin receptor genes in 32 neuroblastoma tumor specimens. All 32 tumor specimens expressed mRNA for c-abl and sst(1); sst(2) mRNA was detected in 27/32 samples and somatostatin mRNA was detected in 30/32 tumor specimens. The remaining receptor subtypes, sst(3), sst(4), and sst(5) were variably expressed. Receptor protein for sst(1) and sst(2) was visualized in tumor neuroblasts as well as in endothelial cells of tumor vessels using immunostaining with specific anti-receptor antibodies. The effect of high expression of somatostatin receptors on cell proliferation was examined in SKNSH neuroblastoma cells transfected with sst(1) and sst(2). SS(14) binding to wild-type SKNSH cells was undetectable; but the native peptide bound with high affinity to the SKNSH/sst(1) and SKNSH/sst(2) neuroblastoma cell lines. Pharmacologic analysis of binding with two long-acting analogues, CH275 and octreotide, confirmed selective expression of sst(1) and sst(2) in stably transfected SKNSH cells. Formation of neuroblastoma xenograft tumors in nude mice was significantly delayed for both SKNSH/sst(1) (P<0.001) and SKNSH/sst(2) (P<0.05) cells compared to wild-type SKNSH. We conclude that: (1) Somatostatin receptors, sst(1) and sst(2), are expressed in the majority of neuroblastomas at diagnosis; and (2) upregulation of functional sst(1) or sst(2) in neuroblastoma cell lines suppresses tumorigenicity in a xenograft model. These observations suggest that somatostatin receptors may be a useful therapeutic target in neuroblastoma.
Assuntos
Neuroblastoma/genética , Receptores de Somatostatina/genética , Animais , Células COS , Transplante de Células , Criança , Pré-Escolar , Feminino , Expressão Gênica , Humanos , Lactente , Recém-Nascido , Masculino , Proteínas de Membrana , Camundongos , Camundongos Nus , Neuroblastoma/patologia , Transplante Heterólogo , Células Tumorais CultivadasRESUMO
Neuroendocrine tumors of the cervix are rare and are often under- or misdiagnosed. Because these tumors are very aggressive, early diagnosis and subsequent treatment are warranted. We describe a 46-yr-old woman with carcinoid syndrome caused by an atypical carcinoid of the uterine cervix. At age 44, she had dysplasia on Pap smear and underwent total abdominal hysterectomy with the diagnosis of adenocarcinoma. Fourteen months postoperatively, she developed the carcinoid syndrome and was found to have numerous liver metastases. Histological and immunohistochemical investigations of biopsy specimens from the patient's liver lesions and original cervical lesion ("adenocarcinoma") suggested that this woman had a primary atypical carcinoid of the uterine cervix with metastases to the liver. Treatment with octreotide and alkylating agents decreased the episodes of flushing and diarrhea within 8 weeks. If an adenocarcinoma of the uterine cervix is diagnosed, atypical carcinoid should be in the differential diagnosis. Symptoms of the carcinoid syndrome should be pursued and, if present, a urinary 5-hydroxyindolacetic acid level should be obtained. Timely diagnosis of a neuroendocrine tumor of the cervix may improve survival.
Assuntos
Tumor Carcinoide/diagnóstico , Neoplasias do Colo do Útero/diagnóstico , Adenocarcinoma , Antineoplásicos Hormonais/uso terapêutico , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Tumor Carcinoide/secundário , Tumor Carcinoide/terapia , Diagnóstico Diferencial , Feminino , Humanos , Imuno-Histoquímica , Neoplasias Hepáticas/tratamento farmacológico , Neoplasias Hepáticas/secundário , Imageamento por Ressonância Magnética , Pessoa de Meia-Idade , Octreotida/administração & dosagem , Neoplasias Pancreáticas/tratamento farmacológico , Neoplasias Pancreáticas/secundário , Teste de Papanicolaou , Síndrome , Neoplasias do Colo do Útero/terapia , Esfregaço VaginalRESUMO
BACKGROUND: Somatostatin receptors are present in most human breast cancers. We performed a pilot trial of intraoperative tumor-gamma detection using the radiolabeled somatostatin analog 125I-lanreotide in 13 women with 14 primary breast carcinomas. METHODS: All patients were given 125I-lanreotide intravenously before surgery. Patients underwent lumpectomy, and postresection margins were evaluated with the gamma probe. Axillary dissection specimens were evaluated ex vivo. RESULTS: Seven of 13 women had gamma probe-positive or clinically suspicious margins re-excised at the time of lumpectomy. Four of six probe-positive margins were histologically positive, and two of six probe-positive margins were histologically negative; a single clinically suspicious margin was histologically positive. A total of 270 axillary lymph nodes were evaluated ex vivo by gamma probe and histology. McNemar's contingency tests demonstrated a highly statistical correlation between histology and gamma probe counts (P < .0001). CONCLUSIONS: The overall accuracy of nodal evaluation with 125I-lanreotide/intraoperative gamma detection was 77%; the negative predictive value of this technique was 97%, however. This technique predicted the presence of tumor in 20% of axillary lymph nodes that were negative by routine histology. This technique appears safe and is able to detect positive tumor resection margins and accurately predict axillary lymph node negativity. Further trials of this technique are required to validate its utility.
Assuntos
Neoplasias da Mama/diagnóstico por imagem , Neoplasias da Mama/cirurgia , Radioisótopos do Iodo , Peptídeos Cíclicos , Somatostatina/análogos & derivados , Idoso , Feminino , Humanos , Período Intraoperatório , Excisão de Linfonodo , Linfonodos/diagnóstico por imagem , Mastectomia Segmentar , Pessoa de Meia-Idade , Projetos Piloto , CintilografiaRESUMO
Radio-labeled somatostatin analogs have recently gained popularity as agents useful in intraoperative tumor localization, external scintigraphy and in situ radiotherapy. We have synthesized and characterized a series of novel N-terminally extended multiply-tyrosinated somatostatin analogs that possess high binding affinity for somatostatin receptors, exhibit biological activity comparable to the native peptide and retain these characteristics after iodination. These analogs can be radio-iodinated to high specific activities. Following radioiodination, these analogs exhibit minimal radiolysis and may be clinically useful for tumor localization, scanning and therapy.
Assuntos
Peptídeos/metabolismo , Somatostatina/análogos & derivados , Somatostatina/farmacologia , Adenocarcinoma Bronquioloalveolar/diagnóstico , Adenocarcinoma Bronquioloalveolar/patologia , Inibidores de Adenilil Ciclases , Idoso , Sequência de Aminoácidos , Neoplasias Encefálicas/diagnóstico , Neoplasias Encefálicas/secundário , Diagnóstico por Imagem , Hormônio do Crescimento/antagonistas & inibidores , Humanos , Iodo/química , Neoplasias Pulmonares/diagnóstico , Neoplasias Pulmonares/patologia , Masculino , Neuroblastoma/tratamento farmacológico , Neuroblastoma/metabolismo , Peptídeos/farmacocinética , Cintilografia/métodos , Somatostatina/síntese química , Distribuição Tecidual , Células Tumorais Cultivadas , Tirosina/químicaRESUMO
BACKGROUND/PURPOSE: Before 1970, treatment decisions for the thyroid lesions in patients with multiple endocrine neoplasia (MEN) were based on physical findings. For the next 20 years, biological markers assumed a preeminent role, and at present, DNA testing is being used to define the need for therapeutic intervention. This report presents a 25-year review of 22 children with MEN-2A, with a mean follow-up of 12.5 years. METHODS: All 22 children underwent a total thyroidectomy, and four (18%) were rendered permanently hypoparathyroid. Since 1976, however, only one patient (6.7%) has lost parathyroid function. Despite the fact that biological screening studies routinely were performed once a year in the majority of our patients and surgery was recommended for any elevation in the serum calcitonin (CT) levels, medullary carcinoma of the thyroid (MTC) developed in 17 children (77%) and only five had C cell hyperplasia (CCH). Thirteen of the 17 had macroscopic tumor described by the pathologist, evidence of recurrent disease (MTC-REC) has developed in four children (24%). RESULTS: There was considerable overlap in both the basal and stimulated CT levels among the five children with CCH, the 13 with localized MTC (MTC-NED), and the four who later had recurrent MTC. The basal calcitonin levels were between 25 and 110 (mean, 58) in the CCH patients, 30 to 1,130 (mean, 184) in the MTC-NED group, and 108 to 201 (mean, 140) in those with recurrent MTC. The corresponding stimulated calcitonin levels were 45 to 417 (mean, 179) in CCH, 111 to 9,510 (mean, 1,407) in MTC-NED, and 449 to 5,093 (mean, 3,383) in MTC-REC. CONCLUSIONS: (1) Basal and pentagastrin-stimulated CT levels did not reliably discriminate between CCH and MTC and should not be used to define the timing of thyroid surgery in children with MEN-2A. (2) Surgical therapy should be undertaken early in childhood on the basis of molecular genetic testing. (3) Postoperative complications are infrequent in the modern era.
Assuntos
Neoplasia Endócrina Múltipla Tipo 2a/cirurgia , Tireoidectomia , Adolescente , Adulto , Calcitonina/sangue , Criança , Pré-Escolar , Feminino , Humanos , Masculino , Neoplasia Endócrina Múltipla Tipo 2a/sangue , Neoplasia Endócrina Múltipla Tipo 2a/patologia , Estudos Retrospectivos , Resultado do TratamentoRESUMO
Gastrinomas and other gastrointestinal neuroendocrine tumors may occur sporadically or as part of the inherited syndrome multiple endocrine neoplasia type 1 (MEN1). Mutations in the recently identified MEN1 gene have been described in sporadic gastrinomas and insulinomas. This study describes techniques used to identify mutations in the MEN1 gene in DNA extracted from paraffin-preserved tissue. Two novel mutations are identified in the MEN1 gene from nine archived paraffin-embedded neuroendocrine tumors, demonstrating that retrospective genetic analysis can be used to identify mutations in the MEN1 gene from preserved tissue. Conditions are provided by which paraffin-embedded tissue can be used as a source of genetic material for sequence information of sufficient quality for mutational studies of the MEN1 gene. It should also be possible to apply this retrospective genetic analysis of paraffin-embedded tissue to other disease models.
Assuntos
Neoplasias Gastrointestinais/genética , Neoplasia Endócrina Múltipla Tipo 1/genética , Proteínas de Neoplasias/genética , Tumores Neuroendócrinos/genética , Neoplasias Pancreáticas/genética , Proteínas Proto-Oncogênicas , DNA de Neoplasias/análise , Neoplasias Duodenais/genética , Neoplasias Duodenais/patologia , Gastrinoma/genética , Gastrinoma/patologia , Neoplasias Gastrointestinais/patologia , Heterozigoto , Humanos , Insulinoma/genética , Insulinoma/patologia , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/patologia , Mutação , Tumores Neuroendócrinos/patologia , Neoplasias Pancreáticas/patologia , Inclusão em Parafina , Neoplasias Gástricas/genética , Neoplasias Gástricas/patologiaRESUMO
OBJECTIVES: To describe the acute cellular response, inflammatory mediator release, and effect on chondrocyte metabolism of interleukin 1 beta (IL-1 beta) in isolated innervated or denervated equine metacarpophalangeal joints. ANIMALS: One metacarpophalangeal joint of 24 adult horses. PROCEDURES: The metacarpophalangeal joint was isolated for 6 hours in a pump-perfused, auto-oxygenated, innervated or denervated metacarpophalangeal joint preparation. Isolated joints were assigned to 4 groups: control, control-denervated, inflamed, and inflamed-denervated, and inflammation was induced by intra-articular injection of IL-1 beta. Synovial fluid was collected for cytologic examination and determination of IL (IL)-1 beta, (IL-6), prostaglandin E2 (PGE2), and substance P (SP) values. Synovial membrane was immunostained with SP and nerve-specific enolase (NSE) antibodies. Cartilage was collected for determination of proteoglycan (PG) synthesis and degradation. RESULTS: IL-1 beta induced significant neutrophilic leukocytosis in synovial and synovial membrane. IL-1 beta concentration and returned to baseline by 5.5 hours, but IL-6 concentration significantly increased throughout the study. Total SP content was significantly higher in inflamed joints. There was a significant increase in 24- and 48-hour PG degradation in inflamed innervated joints. CONCLUSION: Cellular response to IL-1 beta was rapid and sustained; joint clearance of IL-1 beta was rapid, and endogenous production of IL-1 beta did not follow. The IL-6 and PGE2 concentrations significantly increased, and SP content was increased in association with inflammation but not denervation. A degradative response of cartilage of IL-1 beta was observed, and was enhanced by innervation. This model was useful for investigation of the articular response to acute inflammation and the influence of denervation in modulating this response.
Assuntos
Cartilagem Articular/inervação , Cartilagem Articular/fisiologia , Denervação , Inflamação/fisiopatologia , Interleucina-1/farmacologia , Líquido Sinovial/imunologia , Membrana Sinovial/fisiologia , Animais , Pressão Sanguínea , Cartilagem Articular/efeitos dos fármacos , Dinoprostona/análise , Feminino , Cavalos , Inflamação/imunologia , Interleucina-1/análise , Interleucina-6/análise , Articulações , Masculino , Neutrófilos/efeitos dos fármacos , Neutrófilos/imunologia , Orquiectomia , Perfusão/instrumentação , Perfusão/métodos , Fosfopiruvato Hidratase/análise , Substância P/análise , Líquido Sinovial/efeitos dos fármacos , Membrana Sinovial/efeitos dos fármacos , Membrana Sinovial/imunologiaRESUMO
OBJECTIVE: To report on the diagnosis of ectopic corticotropin (adrenocorticotropic hormone [ACTH])-producing bronchial carcinoid tumor by indium-111 pentetreotide (octreotide scan) scintigraphy. METHODS: We present a case of ectopic ACTH syndrome caused by an occult bronchial carcinoid tumor arising in a lymph node and review the pertinent literature. RESULTS: Biochemical diagnosis of ACTH syndrome can be difficult, and conventional imaging modalities often do not demonstrate these small carcinoid tumors. After biochemical proof of the presence of ectopic ACTH syndrome in our patient, conventional radiographic studies did not demonstrate any lesions. An octreotide scan showed a lesion in the lung, which was confirmed surgically. ACTH values returned to normal after resection of the lesion, and octreotide scans confirmed the completeness of surgical resection. The carcinoid tumor originated in a lymph node outside the bronchus. The differential diagnosis of ACTH syndrome, the localization of ectopic ACTH-producing tumors, the bronchial carcinoids, and the uniqueness of the carcinoid tumor arising in a lymph node are briefly discussed. CONCLUSION: Octreotide scintigraphy is useful in localizing occult carcinoid tumors and can be used in the follow-up of patients after successful removal of these tumors.
Assuntos
Neoplasias Encefálicas/química , Neoplasias Encefálicas/patologia , Neoplasias de Tecido Nervoso/química , Neoplasias de Tecido Nervoso/patologia , Neuropeptídeos/análise , Bombesina/análise , Criança , Peptídeo Liberador de Gastrina/análise , Humanos , Tumores Neuroectodérmicos/química , Tumores Neuroectodérmicos/patologia , Neuropeptídeo Y/análise , Neurotensina/análise , Radioimunoensaio , Somatostatina/análise , Peptídeo Intestinal Vasoativo/análiseRESUMO
Somatostatin modulates important physiologic functions of the kidney, including mesangial cell contraction, glomerular prostaglandin synthesis, and phosphate, water and sodium excretion. In diabetic nephropathy, somatostatin inhibits renal hypertrophy. High affinity somatostatin receptors are expressed in the kidney. Circulating somatostatin concentrations, however, are generally well below the affinity constants of known somatostatin receptors. Thus, we hypothesized that somatostatin is produced in the kidney and released locally to act in an autocrine/paracrine manner. Using reverse transcriptase and polymerase chain reaction (RT-PCR) analysis, we found that fresh human renal cortex and cultured human mesangial cells express somatostatin mRNA. Restriction enzyme and Southern blot analysis confirmed that RT-PCR cDNA products were derived from somatostatin mRNA. Radioimmunoassay of mesangial cell culture supernatants demonstrated SS-immunoreactive peptide (87 +/- 30 pg/ml compared to 19 +/- 9 pg/ml in medium not exposed to cells; P < 0.05). In contrast, renal cells did not transcribe detectable levels of vasoactive intestinal peptide (VIP) or neuropeptide Y (NPY) mRNA, nor did they synthesize measurable peptide. Our results demonstrate that renal cells produce somatostatin and suggest that kidney-derived somatostatin may regulate renal function in an autocrine/paracrine manner. Characterization of this pathway may lead to novel methods to alter the course of diabetic nephropathy and other renal diseases.
Assuntos
Mesângio Glomerular/metabolismo , Córtex Renal/metabolismo , Somatostatina/biossíntese , Sequência de Bases , Células Cultivadas , Primers do DNA , Expressão Gênica , Mesângio Glomerular/citologia , Humanos , Córtex Renal/citologia , Dados de Sequência Molecular , Peptídeos/metabolismo , RNA Mensageiro , Radioimunoensaio , Somatostatina/genética , Células Tumorais CultivadasRESUMO
VIP-secreting tumours are rare, but they produce a dramatic clinical picture, the most prominent feature being profuse, watery diarrhoea and hypokalaemia. VIPomas are malignant and require sophisticated diagnostic and localization techniques in order to identify their presence. Delays in diagnosis are the rule rather than the exception. Improvements in the diagnosis of VIPomas appear to result in an increase in resectability rates. A definitive diagnosis is aided by the determination of plasma VIP concentrations through the use of sensitive radioimmunoassays. With heightened awareness of this syndrome, increasing numbers of patients can be identified and more effective treatments developed for the refractory and recurrent tumours.
Assuntos
Neoplasias Pancreáticas/diagnóstico , Vipoma/diagnóstico , Diagnóstico Diferencial , Diagnóstico por Imagem , Humanos , Pâncreas/patologia , Neoplasias Pancreáticas/patologia , Neoplasias Pancreáticas/cirurgia , Síndromes Endócrinas Paraneoplásicas/diagnóstico , Síndromes Endócrinas Paraneoplásicas/patologia , Síndromes Endócrinas Paraneoplásicas/cirurgia , Prognóstico , Radioimunoensaio , Resultado do Tratamento , Peptídeo Intestinal Vasoativo/sangue , Vipoma/patologia , Vipoma/cirurgiaRESUMO
We hypothesized that there is less suppression of whole-body protein breakdown with feeding in patients with cystic fibrosis (CF) who exhibit decreased insulin secretion after a single meal. Using [1-13C]leucine, we measured rates of nonoxidative leucine disappearance (whole-body protein synthesis) and protein breakdown in nine CF patients (6-11 y of age) and five healthy control subjects (8-10 y of age) during feeding and fasting. In the CF patients, synthesis and breakdown (x +/- SD) were 172 +/- 61 and 157 +/- 67 mumol.kg-1.h-1 during feeding and 140 +/- 24 and 178 +/- 26 mumol.kg-1.h-1 during fasting. The respective control values were 129 +/- 27 and 114 +/- 20 mumol.kg-1.h-1 during feeding and 136 +/- 13 and 173 +/- 18 mumol.kg-1.h-1 during fasting. Leucine balance was nearly identical in the two groups. By analysis of variance, there was a significant effect of feeding on protein breakdown but no difference between the groups. However, when each group was analyzed separately, feeding resulted in a 34% decrease in breakdown in the control subjects (P = 0.001) and a 23% increase in synthesis in the CF group (P = 0.058). Plasma insulin concentrations did not differ in the two groups. Thus, feeding may affect protein turnover differently in children with CF than in control children independently of plasma insulin concentration.
Assuntos
Fibrose Cística/metabolismo , Proteínas Alimentares/metabolismo , Ingestão de Alimentos/fisiologia , Estudos de Casos e Controles , Criança , Jejum/metabolismo , Feminino , Alimentos Formulados , Humanos , Infusões Intravenosas , Insulina/sangue , Leucina/administração & dosagem , Leucina/metabolismo , Masculino , Valores de ReferênciaRESUMO
BACKGROUND: Somatostatin inhibits proliferation of many solid tumors. The current study examines whether inhibition of the growth of pancreatic cancer by the somatostatin analog, octreotide, requires tumor expression of somatostatin receptors. METHODS: We studied five human pancreatic cancer cell lines, Capan-1, Capan-2, CAV, MIA PaCa-2, and Panc-1. Solid tumors were established in nude mice (n = 20/cell line) by flank injection of tumor cells. Subcutaneous octreotide (500 micrograms/kg/day) was administered by osmotic pumps to 10 of the animals in each group, and the other 10 received control infusions of saline solution. On day 36, the tumors were excised and weighed. Plasma levels of the putative trophic peptides cholecystokinin, epidermal growth factor (EGF), insulin-like growth factor-1 (IGF-1), and insulin were assessed by radioimmunoassay. Each of the five cell lines was assayed for the presence of cell surface somatostatin receptors by using whole cell competitive binding assays with 125I-somatostatin. Expression of the somatostatin receptor subtype-2 (SSR2) gene was determined with reverse transcriptase-polymerase chain reactions. Southern blot hybridization was used to assess the presence of the SSR2 gene. RESULTS: Octreotide inhibited tumor growth in the MIA PaCa-2 group (512 +/- 75 mg control versus 285 +/- 71 mg treated; p < 0.05) but had no significant effect on tumor weight in the other four cell lines. Plasma levels of cholecystokinin, epidermal growth factor, insulin-like growth factor-1, and insulin were not altered by chronic octreotide infusion. Cell surface somatostatin receptors and SSR2 gene expression were detected only in the MIA PaCa-2 tumors. The gene for the SSR2 receptor was found in all five tumor lines. CONCLUSIONS: Octreotide-mediated inhibition of pancreatic cancer growth is dependent on expression of somatostatin receptors. The expression of somatostatin receptors should be considered in the design and interpretation of clinical trials with somatostatin analogs for treatment of pancreatic cancer.
Assuntos
Antineoplásicos Hormonais/farmacologia , Octreotida/farmacologia , Receptores de Somatostatina/genética , Adenocarcinoma , Animais , Sequência de Bases , Ligação Competitiva/fisiologia , Southern Blotting , Divisão Celular/efeitos dos fármacos , Colecistocinina/sangue , DNA de Neoplasias/análise , Fator de Crescimento Epidérmico/sangue , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Humanos , Insulina/sangue , Fator de Crescimento Insulin-Like I/metabolismo , Camundongos , Camundongos Nus , Dados de Sequência Molecular , Neoplasias Pancreáticas , Peptídeos/sangue , Reação em Cadeia da Polimerase , Células Tumorais Cultivadas/citologia , Células Tumorais Cultivadas/fisiologiaRESUMO
RET germline mutations were found to predispose to the development of three variants of multiple endocrine neoplasia type 2, MEN2A, MEN2B, and familial medullary thyroid carcinoma (FMTC). We have screened for RET mutations at exons 10, 11, 13, and 16 in leukocyte DNA extracted from 37 individuals, and have identified RET germline mutations in 12 affected individuals from 9 unrelated families. No RET germline mutation was found in 19 individuals with apparent sporadic diseases. We have also screened for RET mutations at exons 10, 11, and 16 in tumor DNA extracted from 13 freshly frozen medullary thyroid carcinomas (MTC). RET mutation was detected in every tumor, either inherited or sporadic, indicating that RET plays an important role in the development of both inherited and sporadic MTC. We initially screened for RET mutations by direct DNA sequencing of the genomic PCR products amplified from patients' leukocyte or tumor DNA. Recently, we utilized the "Cold SSCP" method, nonradioactive single-stranded conformation polymorphism analysis, to screen for RET mutations and have identified a novel mutation, a 6-bp deletion preceding the cysteine-634, in a sporadic MTC.