RESUMO
Hemangioblastomas associated with von Hippel-Lindau (VHL) disease are frequently multiple and recur during prolonged follow-up. Currently, no systemic treatment is available for these tumors. Recent studies have shown the expression of somatostatin receptors in these types of hemangioblastomas. Notably, increased somatostatin receptor expression in a tumor, as determined by peptide-receptor radionuclide imaging, is a predictive factor of response to treatment with somatostatin analogs and peptide-receptor radionuclide therapy. The aim of this study was to describe the case of a patient with increased expression of somatostatin receptors in a suprasellar hemangioblastoma associated with VHL disease and conduct a literature review on somatostatin receptor expression in patients with VHL-associated hemangioblastomas. We describe herein the case of a 51-year-old man with VHL disease who had a suprasellar hemangioblastoma detected on magnetic resonance imaging. Peptide-receptor radionuclide imaging using gallium-68-DOTATOC (68Ga-DOTATOC) identified increased expression of somatostatin receptors in the suprasellar hemangioblastoma, along with multiple pancreatic neuroendocrine tumors and bilateral pheochromocytomas. The patient was treated for 1 year with lanreotide, a somatostatin analog. A repeat 68Ga-DOTATOC 1 year after starting lanreotide revealed decreased radiotracer uptake by the hemangioblastoma, consistent with a metabolic response. The presence of somatostatin receptors in hemangioblastomas associated with VHL disease is a novel finding. The decreased expression of these receptors after treatment with a somatostatin analog, as described in the present case, positions the somatostatin receptor as a new target for novel diagnostic, therapeutic, and follow-up opportunities in patients with VHL disease.
Assuntos
Hemangioblastoma , Receptores de Somatostatina , Doença de von Hippel-Lindau , Humanos , Hemangioblastoma/diagnóstico por imagem , Doença de von Hippel-Lindau/complicações , Receptores de Somatostatina/análise , Receptores de Somatostatina/metabolismo , Masculino , Pessoa de Meia-Idade , Octreotida/uso terapêutico , Octreotida/análogos & derivados , Neoplasias Cerebelares/diagnóstico por imagem , Neoplasias Cerebelares/tratamento farmacológico , Seguimentos , Imageamento por Ressonância Magnética , Compostos Radiofarmacêuticos/uso terapêuticoRESUMO
Somatic growth in vertebrates is regulated endocrinologically by the somatotropic axis, headed by the growth hormone (GH) and the insulin growth factor-I (IGF-I). Somatostatin (Sst), a peptide hormone synthesized in the hypothalamus, modulates GH actions through its receptors (Sstr). Four Sstr subtypes (Sstr 1-3 and 5) have been identified in teleosts. However, little is known about whether they have a specific function or tissue expression. The aim of this study was to determine the role of sstr2 and sstr5 in the growth of the medaka (Oryzias latipes). The assessed expression pattern across diverse tissues highlighted greater prevalence of sstr1 and sstr3 in brain, intestine and muscle than in pituitary or liver. The expression of sstr2 was high in all the tissues tested, while sstr5 was predominantly expressed in the pituitary gland. A CRISPR/Cas9 sstr5 mutant with loss of function (sstr5-/-) was produced. Assessment of sstr5-/- indicated no significant difference with the wild type regarding growth parameters such as standard length, body depth, or peduncle depth. Furthermore, the functional loss of sstr5 had no impact on the response to a nutritional challenge. The fact that several sstr subtypes were upregulated in different tissues in sstr5-/- medaka suggests that in the mutant fish, there may be a compensatory effect on the different tissues, predominantly by sstr1 in the liver, brain and pituitary, with sstr2 being upregulated in pituitary and liver, and sstr3 only presenting differential expression in the brain. Analysis of the sstr subtype and the sstr5-/- fish showed that sstr5 was not the only somatostatin receptor responsible for Sst-mediated Gh regulation.
Assuntos
Hormônio do Crescimento Humano , Oryzias , Animais , Receptores de Somatostatina/genética , Receptores de Somatostatina/metabolismo , Oryzias/genética , Oryzias/metabolismo , Hormônio do Crescimento/genética , Hormônio do Crescimento Humano/metabolismoRESUMO
CONTEXT: Invasive and somatostatin receptor ligand (SRL)-resistant pituitary tumors represent a challenge in the clinical practice of endocrinologists. Efforts have been made to elucidate reliable makers for both. Survivin and eukaryotic translation initiation factor-binding protein 1 (4EBP1) are upregulated in several cancers and involved in apoptosis and cell proliferation. OBJECTIVE: We explored the role of these markers in somatotropinomas. METHODS: Immunostains for survivin and 4EBP1, and also for somatostatin receptor type 2 (SSTR2), Ki-67, and cytokeratin 18, were analyzed in tissue microarrays containing 52 somatotropinoma samples. Tumor invasiveness was evaluated in all samples while drug resistance was evaluated in 34 patients who received SRL treatment. All these parameters were correlated with first-generation SRL (fg-SRL) responsiveness and tumor invasiveness. RESULTS: Low survivin expression (P = 0.04), hyperintense signal on T2 weighted image (T2WI) (P = 0.01), younger age (P = 0.01), sparsely granular adenomas (SGA) (P = 0.04), high postoperative growth hormone (GH) and insulin-like growth factor-1 (IGF-1) levels (P = 0.049 and P < 0.001, respectively), and large postoperative tumor size (P = 0.02) were associated with resistance to fg-SRL. Low survivin and SSTR2 expression and high 4EBP1 expression were associated with SGA (P = 0.04, P = 0.01, and P = 0.001, respectively). Younger age (P = 0.03), large tumor pre- and postoperative (P = 0.04 and P = 0.006, respectively), low SSTR2 expression (P = 0.03), and high baseline GH and IGF-1 (P = 0.01 and P = 0.02, respectively) were associated with tumor invasiveness. However, survivin, 4EBP1, Ki-67, and granulation patterns were not associated with tumor invasion. CONCLUSION: This study suggests that low survivin expression is predictive of resistance to fg-SRL in somatotropinomas, but not of tumor invasiveness.
Assuntos
Acromegalia , Adenoma , Hormônio do Crescimento Humano , Neoplasias Hipofisárias , Humanos , Receptores de Somatostatina/metabolismo , Somatostatina/uso terapêutico , Fator de Crescimento Insulin-Like I , Acromegalia/tratamento farmacológico , Survivina/uso terapêutico , Antígeno Ki-67 , Adenoma/metabolismo , Hormônio do Crescimento Humano/uso terapêutico , Neoplasias Hipofisárias/tratamento farmacológico , Hormônio do Crescimento/uso terapêuticoRESUMO
Acromegaly is a chronic and systemic disease due to excessive growth hormone and insulin-like growth factor type I caused, in the vast majority of cases, by a GH-secreting pituitary adenoma. About 40% of these tumors have somatic mutations in the stimulatory G protein alpha-subunit 1 gene. The pathogenesis of the remaining tumors, however, is still not fully comprehended. Surgery is the first-line therapy for these tumors, and first-generation somatostatin receptor ligands (fg-SRL) are the most prescribed medications in patients who are not cured by surgery. MicroRNAs are small, non-coding RNAs that control the translation of many mRNAs, and are involved in the post-transcriptional regulation of gene expression. Differentially expressed miRNAs can explain differences in the pathogenesis of acromegaly and tumor resistance. In this review, we focus on the most validated miRNAs, which are mainly involved in acromegaly's tumorigenesis and fg-SRL resistance, as well as in circulating miRNAs in acromegaly.
Assuntos
Acromegalia , Adenoma , Hormônio do Crescimento Humano , MicroRNAs , Acromegalia/genética , Adenoma/metabolismo , Hormônio do Crescimento Humano/uso terapêutico , Humanos , Fator de Crescimento Insulin-Like I/metabolismo , MicroRNAs/genética , MicroRNAs/uso terapêutico , Receptores de Somatostatina/genética , Receptores de Somatostatina/metabolismo , Somatostatina/genética , Somatostatina/uso terapêuticoRESUMO
Currently, the first-generation somatostatin receptor ligands (fg-SRLs), octreotide LAR and lanreotide autogel, are the mainstays of acromegaly treatment and achieve biochemical control in approximately 40% of patients and tumor shrinkage in over 60% of patients. Pasireotide, a second-generation SRL, shows higher efficacy with respect to both biochemical control and tumor shrinkage but has a worse safety profile. In this review, we discuss the future perspectives of currently available SRLs, focusing on the use of biomarkers of response and precision medicine, new formulations of these SRLs and new drugs, which are under development. Precision medicine, which is based on biomarkers of response to treatment, will help guide the decision-making process by allowing physicians to choose the appropriate drug for each patient and improving response rates. New formulations of available SRLs, such as oral, subcutaneous depot, and nasal octreotide, may improve patients' adherence to treatment and quality of life since there will be more options available that better suit each patient. Finally, new drugs, such as paltusotine, somatropin, ONO-5788, and ONO-ST-468, may improve treatment adherence and present higher efficacy than currently available drugs.
Assuntos
Acromegalia/tratamento farmacológico , Antineoplásicos Hormonais/administração & dosagem , Adenoma Hipofisário Secretor de Hormônio do Crescimento/tratamento farmacológico , Receptores de Somatostatina/metabolismo , Acromegalia/sangue , Acromegalia/etiologia , Antineoplásicos Hormonais/efeitos adversos , Biomarcadores Tumorais/sangue , Adenoma Hipofisário Secretor de Hormônio do Crescimento/sangue , Adenoma Hipofisário Secretor de Hormônio do Crescimento/complicações , Adenoma Hipofisário Secretor de Hormônio do Crescimento/genética , Humanos , Octreotida/administração & dosagem , Octreotida/efeitos adversos , Peptídeos Cíclicos/administração & dosagem , Peptídeos Cíclicos/efeitos adversos , Medicina de Precisão/métodos , Medicina de Precisão/tendências , Qualidade de Vida , Ensaios Clínicos Controlados Aleatórios como Assunto , Somatostatina/administração & dosagem , Somatostatina/efeitos adversos , Somatostatina/análogos & derivados , Resultado do TratamentoRESUMO
Octreotide (OCT) is used to inhibit hormone secretion and growth in somatotroph tumors, although a significant percentage of patients are resistant. It has also been tested in nonfunctioning (NF) tumors but with poor results, with these outcomes having been associated with SSTR2 levels and impaired signaling. We investigated whether OCT inhibitory effects can be improved by TGF-ß1 in functioning and nonfunctioning somatotroph tumor cells. OCT effects on hormone secretion and proliferation were analyzed in the presence of TGF-ß1 in WT and SSTR2-overexpressing secreting GH3 and silent somatotroph tumor cells. The mechanism underlying these effects was assessed by studying SSTR and TGFßR signaling pathways mediators. In addition, we analyzed the effects of OCT/TGF-ß1 treatment on tumor growth and cell proliferation in vivo. The inhibitory effects of OCT on GH- and PRL-secretion and proliferation were improved in the presence of TGF-ß1, as well as by SSTR2 overexpression. The OCT/TGF-ß1 treatment induced downregulation of pERK1/2 and pAkt, upregulation of pSmad3, and inhibition of cyclin D1. In vivo experiments showed that OCT in the presence of TGF-ß1 blocked tumor volume growth, decreased cell proliferation, and increased tumor necrosis. These results indicate that SSTR2 levels and the stimulation of TGF-ß1/TGFßR/Smad2/3 pathway are important for strengthening the antiproliferative and antisecretory effects of OCT.
Assuntos
Antineoplásicos Hormonais/farmacologia , Proliferação de Células/efeitos dos fármacos , Octreotida/farmacologia , Neoplasias Hipofisárias/tratamento farmacológico , Proteína Smad2/metabolismo , Proteína Smad3/metabolismo , Somatotrofos/efeitos dos fármacos , Fator de Crescimento Transformador beta1/farmacologia , Animais , Linhagem Celular , Feminino , Humanos , Camundongos Nus , Fosforilação , Neoplasias Hipofisárias/genética , Neoplasias Hipofisárias/metabolismo , Neoplasias Hipofisárias/patologia , Ratos , Receptores de Somatostatina/genética , Receptores de Somatostatina/metabolismo , Transdução de Sinais , Somatotrofos/metabolismo , Somatotrofos/patologia , Carga Tumoral/efeitos dos fármacosRESUMO
PURPOSE: Pancreatic Polypeptide-secreting tumor of the distal pancreas (PPoma) is a rare, difficult and indolent type of cancer with a survival rate of 5-year in only 10% of all cases. The PPoma is classified as a neuroendocrine tumor (NET) not functioning that overexpresses SSTR 2 (somatostatin receptor subtype 2). Thus, in order to improve the diagnosis of this type of tumor, we developed nanoparticulate drug carriers based on poly-lactic acid (PLA) polymer loaded with octreotide and radiolabeled with Technetium-99 m (99mTc). METHODS: PLA/PVA octreotide nanoparticles were developed by double-emulsion technique. These nanoparticles were characterized by Atomic Force Microscopy (AFM) and Dynamic Light Scattering (DLS) and radiolabeled with 99mTc by the direct via forming 99mTc-PLA/PVA octreotide nanoparticles. The safety of these nanosystems was evaluated by the MTT cell toxicity assay and their in vivo biodistribution was evaluated in xenografted inducted animals. RESULTS: The results showed that a 189 nm sized nanoparticle were formed with a PDI of 0,097, corroborating the monodispersive behavior. These nanoparticles were successfully radiolabeled with 99mTc showing uptake by the inducted tumor. The MTT assay corroborated the safety of the nanosystem for the cells. CONCLUSION: The results support the use of this nanosystem (99mTc-PLA/PVA octreotide nanoparticles) as imaging agent for PPoma. Graphical Abstract Polypeptide-Secreting Tumor of the Distal Pancreas (PPoma) Radiolabeled Nanoparticles for Imaging.
Assuntos
Carcinoma Ductal Pancreático/diagnóstico por imagem , Nanopartículas/química , Octreotida/química , Neoplasias Pancreáticas/diagnóstico por imagem , Polipeptídeo Pancreático/metabolismo , Poliésteres/química , Compostos Radiofarmacêuticos/química , Tecnécio/química , Animais , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Humanos , Masculino , Camundongos Endogâmicos BALB C , Camundongos Nus , Nanopartículas/metabolismo , Octreotida/metabolismo , Pâncreas/diagnóstico por imagem , Pâncreas/metabolismo , Neoplasias Pancreáticas/metabolismo , Tamanho da Partícula , Cintilografia/métodos , Compostos Radiofarmacêuticos/metabolismo , Receptores de Somatostatina/genética , Receptores de Somatostatina/metabolismo , Distribuição Tecidual , Neoplasias PancreáticasRESUMO
Animal studies have shown that antagonists of receptor 1 of Melanin-Concentrating Hormone (MCH-R1) elicit antidepressive-like behavior, suggesting that MCH-R1 might be a novel target for the treatment of depression and supports the hypothesis that MCHergic signaling regulates depressive-like behaviors. Consistent with the evidence that MCHergic neurons send projections to dorsal and median raphe nuclei, we have previously demonstrated that MCH microinjections in both nuclei induced a depressive-like behavior. Even though MCH neurons also project to Locus Coeruleus (LC), only a few studies have reported the behavioral and neurochemical effect of MCH into the LC. We studied the effects of MCH (100 and 200 ng) into the LC on coping-stress related behaviors associated with depression, using two different behavioral tests: the forced swimming test (FST) and the learned helplessness (LH). To characterize the functional interaction between MCH and the noradrenergic LC system, we also evaluated the neurochemical effects of MCH (100 ng) on the extracellular levels of noradrenaline (NA) in the medial prefrontal cortex (mPFC), an important LC terminal region involved in emotional processing. MCH administration into the LC elicited a depressive-like behavior evidenced in both paradigms. Interestingly, in the LH, MCH (100) elicited a significant increase in escape failures only in stressed animals. A significant decrease in prefrontal levels of NA was observed after MCH microinjection into the LC. Our results demonstrate that increased MCH signaling into the LC triggers depressive-like behaviors, especially in stressed animals. These data further corroborate the important role of MCH in the neurobiology of depression.
Assuntos
Hormônios Hipotalâmicos/farmacologia , Locus Cerúleo/metabolismo , Melaninas/farmacologia , Hormônios Hipofisários/farmacologia , Receptores de Somatostatina/metabolismo , Animais , Antidepressivos/farmacologia , Depressão/induzido quimicamente , Depressão/fisiopatologia , Núcleo Dorsal da Rafe/efeitos dos fármacos , Núcleo Dorsal da Rafe/metabolismo , Emoções/efeitos dos fármacos , Hormônios Hipotalâmicos/metabolismo , Locus Cerúleo/efeitos dos fármacos , Masculino , Melaninas/metabolismo , Neurônios/fisiologia , Norepinefrina/análise , Hormônios Hipofisários/metabolismo , Córtex Pré-Frontal/efeitos dos fármacos , Córtex Pré-Frontal/metabolismo , Ratos , Ratos Wistar , Receptores de Somatostatina/antagonistas & inibidores , Estresse Psicológico/metabolismo , Estresse Psicológico/fisiopatologiaRESUMO
OBJECTIVE: To review the literature on the clinical application of radiolabeled somatostatin receptor scintigraphy (SRS) by SPECT and PET in adults with chronic inflammatory diseases. RESEARCH DESIGN: Systematic review of published observational studies between 1993 and 2017. DATA COLLECTION AND ANALYSIS: The Cochrane Central Register of Controlled Trials, MedLine, EMBASE, PubMed, Google Scholar, OVID, EBSCO, Scopus, and Web of Science were used to search for studies on the use of SRS in adults with chronic inflammatory diseases. A team of reviewers independently screened for eligible studies. Quality of evidence was assessed by QUADAS approach. RESULTS: Eligible papers included 38 studies. Studied populations were heterogeneous, and patients were classified according to the diagnosed disease: endothelial inflammation, rheumatoid arthritis, cardiac allograft rejection, granulomatous diseases, small vessel vasculitis, idiopathic pulmonary fibrosis, sarcoidosis, and thyroid exophthalmopathy. Because of many quality differences between studies, it was not possible to pool data, and a narrative synthesis is reported. CONCLUSION: Results highlight the value of SRS to detect active inflammation in several chronic inflammatory conditions, despite the bias related to the index test, showing lack of standardization of the scintigraphic technique and high variability of methods used to clinically evaluate inflammatory condition.
Assuntos
Inflamação/diagnóstico por imagem , Inflamação/metabolismo , Tomografia por Emissão de Pósitrons/métodos , Receptores de Somatostatina/metabolismo , Tomografia Computadorizada de Emissão de Fóton Único/métodos , Doença Crônica , HumanosRESUMO
The melanin-concentrating hormone (MCH) is a peptidergic neuromodulator synthesized by neurons of the posterior hypothalamus and incerto-hypothalamic area. These neurons project throughout the central nervous system, including the dorsal raphe nucleus (DRN). In rodents, MCH exerts its biological functions through the MCHR-1 receptor. We previously demonstrated that intra-DRN MCH administration increases REM sleep time and induces a pro-depressive behavior. We also determined that MCH modulates the neuronal firing rate and serotonin release within this nucleus. Previous studies in mice identified the presence of MCHR-1 in neurons located in the olfactory tubercle, hypothalamus, and nucleus accumbens, in a specialized neuronal appendage: the neuronal primary cilia. However, the subcellular location of MCHR-1 protein in the DRN is still unknown. Hence, the aim of the present study was to explore, by means of single and double immunohistochemical procedures, whether MCHR-1 is present in neuronal primary cilia in serotonergic and GABAergic neurons located in the DRN of the rat. We demonstrated colocalization of MCHR-1 with type III adenylyl cyclase (AC-III), a neuronal ciliary marker, in the DRN and confirmed their colocalization in the hippocampus and cerebral cortex of the rat. We quantified the proportion of serotoninergic and GABAergic neurons that coexpress MCHR-1 at the mid-caudal and mid-rostral levels of the DRN: 4% and 12%, respectively. Furthermore, approximately 10% of the total number of MCHR-1 immunoreactive primary cilia belonged to serotonergic neurons, whilst 12% were appendages of GABAergic neurons. These morphological data allow us to conclude that the mechanism by which MCH modulates the activity of DRN neurons is through MCHR-1 receptors present in the primary cilia of different neurochemical phenotypes. New experiments are needed to understand the functional rationale of the unexpected localization of these receptors and to explore their presence in other neuronal phenotypes.