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1.
J Neurosci ; 41(36): 7514-7531, 2021 09 08.
Artigo em Inglês | MEDLINE | ID: mdl-34301828

RESUMO

Primary cilia exhibit a distinct complement of proteins, including G-protein-coupled receptors (GPCRs) that mediate sensory and developmental signals. The localization of GPCRs to the ciliary membrane involves ciliary localization sequences (CLSs), but it is not known how CLSs might relate to cilium type. Here, we studied the localization of two rhodopsin (RHO)-like GPCRs, somatostatin receptor (SSTR3) and RHO, in three types of cilia, from inner medullary collecting duct (IMCD3) cells, hTERT-RPE1 cells (possessing pocket cilia), and rod photoreceptors (whose cilia grow into elaborate phototransductive outer segments). SSTR3 was localized specifically to all three types of cilia, whereas RHO showed more selectivity for the photoreceptor cilium. Focusing on C-terminal CLSs, we characterized a novel CLS in the SSTR3 C terminus, which was required for the robust ciliary localization of SSTR3. Replacing the C terminus of RHO with this SSTR3 CLS-enhanced ciliary localization, compared with full-length RHO in IMCD3 and hTERT-RPE1 cells. Addition of the SSTR3 CLS to the single transmembrane protein CD8A enabled ciliary localization. In hTERT-RPE1 cells, a partial SSTR3 CLS added to CD8A effected specific localization to the periciliary (pocket) membrane, demonstrating C-terminal localization sequence targeting to this domain. Using retinas from mice, including both sexes, we show that deletion of the C terminus of RHO reduced the rod outer segment localization and that addition of the SSTR3 C-terminal CLS to the truncated RHO partly rescued this mislocalization. Overall, the study details elements of the different C termini of SSTR3 and RHO that are major effectors in determining specificity of cilium (or pericilium) localization among different types of cilia.SIGNIFICANCE STATEMENT The localization of G-protein-coupled receptors to primary cilia is key to many types of signal transduction. After characterizing a novel C-terminal CLS in SSTR3, we investigated how SSTR3 and RHO localization to the cilium relates to C-terminal CLSs and to cilium type. We found that the SSTR3 C-terminal CLS was effective in three different types of cilia, but the RHO C terminus showed a clear localization preference for the highly elaborate photoreceptor cilium. When added to CD8A, part of the SSTR3 CLS promoted specific periciliary membrane localization in hTERT-RPE1 cells, demonstrating an effective CLS for this domain. Thus, we demonstrate that elements of the C termini of SSTR3 and RHO determine different localization patterns among different types of cilia.


Assuntos
Cílios/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Receptores de Somatostatina/metabolismo , Células Fotorreceptoras Retinianas Bastonetes/metabolismo , Rodopsina/metabolismo , Animais , Linhagem Celular , Humanos , Camundongos , Retina/metabolismo , Transdução de Sinais/fisiologia
2.
Int J Mol Sci ; 22(11)2021 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-34070785

RESUMO

Somatostatin is widely diffused in the central nervous system, where it participates to control the efficiency of synaptic transmission. This peptide mainly colocalizes with GABA, in inhibitory, GABA-containing interneurons from which it is actively released in a Ca2+ dependent manner upon application of depolarizing stimuli. Once released in the synaptic cleft, somatostatin acts locally, or it diffuses in the extracellular space through "volume diffusion", a mechanism(s) of distribution which mainly operates in the cerebrospinal fluid and that assures the progression of neuronal signalling from signal-secreting sender structures towards receptor-expressing targeted neurons located extrasynaptically, in a non-synaptic, inter-neuronal form of communication. Somatostatin controls the efficiency of central glutamate transmission by either modulating presynaptically the glutamate exocytosis or by metamodulating the activity of glutamate receptors colocalized and functionally coupled with somatostatin receptors in selected subpopulations of nerve terminals. Deciphering the role of somatostatin in the mechanisms of "volume diffusion" and in the "receptor-receptor interaction" unveils new perspectives in the central role of this fine tuner of synaptic strength, paving the road to new therapeutic approaches for the cure of central disorders.


Assuntos
Sistema Nervoso Central/metabolismo , Ácido Glutâmico/metabolismo , Interneurônios/metabolismo , Neurônios/metabolismo , Receptores de Somatostatina/genética , Somatostatina/genética , Sinapses/metabolismo , Animais , Cálcio/metabolismo , Sistema Nervoso Central/citologia , AMP Cíclico/metabolismo , Regulação da Expressão Gênica , Humanos , Interneurônios/citologia , Neurônios/citologia , Potássio/metabolismo , Receptores de Glutamato Metabotrópico/genética , Receptores de Glutamato Metabotrópico/metabolismo , Receptores de N-Metil-D-Aspartato/genética , Receptores de N-Metil-D-Aspartato/metabolismo , Receptores de Somatostatina/metabolismo , Somatostatina/metabolismo , Transmissão Sináptica
3.
Drug Des Devel Ther ; 15: 2385-2399, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34103899

RESUMO

Purpose: Many researches have investigated the functions of tetramethylpyrazine (TMP) in Alzheimer's disease (AD). This study aimed to discuss the underlying mechanism of TMP in AD mice. Methods: TMP (200 mg/kg) was administered to 6-month-old APP/PS1 transgenic mice, and behavioral changes and hippocampal nerve injury in AD mice were detected. Apoptosis and autophagy-related protein levels were detected. Changes in gene expression before and after TMP treatment were compared using transcriptome sequencing. The effects of Cullin 4B (CUL4B) overexpression and somatostatin receptor 4 (SSTR4) silencing on AD symptoms and SSTR4 ubiquitination in APP/PS1 mice were observed. SH-SY5Y and PC12 cells were treated with 25 µmol/L Aß25-35 and TMP to observe cell viability, apoptosis, and autophagy. Cell viability and apoptosis were measured again after treatment with proteasome inhibitor MG132 or lysosomal inhibitor 3-mA. Results: TMP treatment improved the behavioral cognition of APP/PS1 mice and improved the neuronal apoptosis and damage in brain tissue. CUL4B was significantly upregulated in APP/PS1 mouse brain tissue, and SSRT4 protein was downregulated, and the levels of CUL4B and SSRT4 were negatively correlated. TMP treatment downregulated CUL4B, inhibited SSRT4 ubiquitination and upregulated SSRT4 protein level in APP/PS1 mouse brain tissue, while CUL4B overexpression or SSRT4 silencing reversed the effect of TMP. TMP and MG132 improved the decreased activity, increased apoptosis and increased SSRT4 protein in SH-SY5Y and PC12 cells treated with Aß25-35, but not 3-mA. CUL4B overexpression promoted the ubiquitination of SSTR4 in cells, which partially reversed the effect of TMP. Conclusion: TMP could improve the cognitive ability of AD mice by inhibiting CUL4B expression and the ubiquitination degradation of SSTR, and alleviating neuronal apoptosis and injury. This study may offer a new therapeutic option for AD treatment.


Assuntos
Doença de Alzheimer/tratamento farmacológico , Pirazinas/farmacologia , Receptores de Somatostatina/antagonistas & inibidores , Doença de Alzheimer/metabolismo , Animais , Cognição/efeitos dos fármacos , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Ratos , Receptores de Somatostatina/genética , Receptores de Somatostatina/metabolismo , Células Tumorais Cultivadas , Ubiquitinação/efeitos dos fármacos
4.
Int J Cancer ; 149(5): 1129-1136, 2021 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-33990938

RESUMO

Aloe-emodin (1,8-dihydroxy-3-[hydroxymethyl]-anthraquinone), AE, is one of the active constituents of a number of plant species used in traditional medicine. We have previously identified, for the first time, AE as a new antitumor agent and shown that its selective in vitro and in vivo killing of neuroblastoma cells was promoted by a cell-specific drug uptake process. However, the molecular mechanism underlying the cell entry of AE has remained elusive as yet. In this report, we show that AE enters tumor cells via two of the five somatostatin receptors: SSTR2 and SSTR5. This observation was suggested by gene silencing, receptor competition, imaging and molecular modeling experiments. Furthermore, SSTR2 was expressed in all surgical neuroblastoma specimens we analyzed by immunohistochemistry. The above findings have strong implications for the clinical adoption of this natural anthraquinone molecule as an antitumor agent.


Assuntos
Aloe/química , Antineoplásicos Fitogênicos/farmacologia , Biomarcadores Tumorais/metabolismo , Emodina/farmacologia , Neoplasias/tratamento farmacológico , Receptores de Somatostatina/metabolismo , Apoptose , Biomarcadores Tumorais/genética , Proliferação de Células , Humanos , Neoplasias/genética , Neoplasias/metabolismo , Neoplasias/patologia , Espécies Reativas de Oxigênio/metabolismo , Receptores de Somatostatina/genética , Células Tumorais Cultivadas
5.
Clin Nucl Med ; 46(6): e312-e316, 2021 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-33826573

RESUMO

PURPOSE: Neurofibromatosis type 2 (NF2) is a genetic disorder that is associated with multiple tumors of the nervous system, and approximately one half of patients present with meningiomas. For patients with multifocal disease, somatostatin receptor-targeted peptide receptor radionuclide therapy (PRRT) might be a suitable systemic treatment option. PATIENTS AND METHODS: Between March 2015 and August 2017, 11 NF2 patients (7 females and 4 males; mean age, 39 ± 12 years) with multifocal, progressive meningiomas underwent a median of 4 cycles of PRRT (range, 2-6 cycles). Acute and chronic adverse events were recorded according to National Institutes of Health's Common Toxicity Criteria (CTC) version 5.0. Follow-up MRIs (every 3 to 6 months), using the Response Assessment in Neuro-Oncology response criteria for meningiomas, were used to assess treatment responses. RESULTS: Peptide receptor radionuclide therapy was well tolerated in all patients without any relevant acute adverse effects. Transient hematologic toxicity (CTC grade 3) was observed in 2 subjects. Somatostatin receptor-directed radiopeptide therapy resulted in radiological disease stabilization in 6 of 11 patients. Median progression-free survival was 12 months (range, 1-55 months), and overall survival was 37 months (range, 5-61 months). CONCLUSIONS: Based on our retrospective pilot data, PRRT is feasible and well-tolerated in NF2 patients. It might offer a suitable treatment option in subjects with multiple, recurrent, or treatment-refractory meningiomas.


Assuntos
Neurofibromatose 2/radioterapia , Receptores de Somatostatina/metabolismo , Adulto , Idoso , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Neurofibromatose 2/diagnóstico por imagem , Neurofibromatose 2/metabolismo , Octreotida/uso terapêutico , Estudos Retrospectivos
6.
Cells ; 10(3)2021 03 06.
Artigo em Inglês | MEDLINE | ID: mdl-33800837

RESUMO

Central actions of leptin and insulin on hepatic lipid metabolism can be opposing and the mechanism underlying this phenomenon remains unclear. Both hormones can modulate the central somatostatinergic system that has an inhibitory effect on growth hormone (GH) expression, which plays an important role in hepatic metabolism. Using a model of chronic central leptin infusion, we evaluated whether an increase in central leptin bioavailability modifies the serum lipid pattern through changes in hepatic lipid metabolism in male rats in response to an increase in central insulin and the possible involvement of the GH axis in these effects. We found a rise in serum GH in leptin plus insulin-treated rats, due to an increase in pituitary GH mRNA levels associated with lower hypothalamic somatostatin and pituitary somatostatin receptor-2 mRNA levels. An augment in hepatic lipolysis and a reduction in serum levels of non-esterified fatty acids (NEFA) and triglycerides were found in leptin-treated rats. These rats experienced a rise in lipogenic-related factors and normalization of serum levels of NEFA and triglycerides after insulin treatment. These results suggest that an increase in insulin in leptin-treated rats can act on the hepatic lipid metabolism through activation of the GH axis.


Assuntos
Hipotálamo/efeitos dos fármacos , Insulina/farmacologia , Leptina/farmacologia , Metabolismo dos Lipídeos/efeitos dos fármacos , Fígado/efeitos dos fármacos , Hipófise/efeitos dos fármacos , Animais , Ácidos Graxos não Esterificados/sangue , Regulação da Expressão Gênica , Hormônio do Crescimento/genética , Hormônio do Crescimento/metabolismo , Hipotálamo/metabolismo , Injeções Intravenosas , Injeções Intraventriculares , Insulina/metabolismo , Leptina/metabolismo , Metabolismo dos Lipídeos/genética , Fígado/metabolismo , Masculino , Hipófise/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ratos , Ratos Wistar , Receptores de Somatostatina/genética , Receptores de Somatostatina/metabolismo , Transdução de Sinais , Triglicerídeos/sangue
7.
PLoS One ; 16(4): e0249988, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33886620

RESUMO

PURPOSE: We investigated the effect of octreotide, a long-acting somatostatin (SST) analogue, on IGF-1 secretion and its possible mechanism of action in orbital fibroblasts (OFs) from patients with thyroid-associated ophthalmopathy (TAO). MATERIALS AND METHODS: OFs were isolated from the orbital fat of patients with TAO or healthy individuals. The expression level of insulin-like growth factor (IGF)-1, at the protein and mRNA level, was determined with ELISA and quantitative RT-PCR, respectively. The expression pattern of somatostatin receptor (SSTR) 2, which has the highest affinity for octreotide, was examined by flow cytometry. The activity of NF-κB pathway was determined by examining the levels of phosphorylation of IKKα/ß and p65, and degradation of IκB via western blot analysis, and by measuring the activity of NF-kB-dependent luciferase via transfection with plasmids containing luciferase and NF-κB binding site. RESULTS: OFs from patients with TAO showed significantly higher levels of IGF-1 secretion and NF-κB activity even in the absence of stimulation, compared to those from controls. Treatment with octreotide reduced the level of IGF-1 secretion in OFs from patients with TAO, but not in OFs from controls. OFs from patients with TAO expressed higher levels of SSTR2 on the cell surface, compared to controls. In addition, the expression of IGF-1 at the protein and mRNA level was dependent on the activity of NF-κB pathway in OFs from patients with TAO. Furthermore, treatment with octreotide reduced on the activity of NF-κB pathway in OFs from patients with TAO. CONCLUSION: OFs from patients with TAO showed significantly higher levels of IGF-1 secretion via up-regulation of NF-κB activity. Treatment with octreotide inhibited the secretion of IGF-1 by reducing the NF-κB pathway in OFs, which expressed higher levels of SSRT2 on the cell surface, from patients with TAO.


Assuntos
Oftalmopatia de Graves/metabolismo , Fator de Crescimento Insulin-Like I/metabolismo , NF-kappa B/metabolismo , Octreotida/farmacologia , Órbita/citologia , Receptores de Somatostatina/metabolismo , Regulação para Cima/efeitos dos fármacos , Adulto , Idoso , Estudos de Casos e Controles , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Feminino , Fibroblastos/citologia , Fibroblastos/efeitos dos fármacos , Fibroblastos/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Oftalmopatia de Graves/tratamento farmacológico , Oftalmopatia de Graves/genética , Humanos , Fator de Crescimento Insulin-Like I/genética , Masculino , Pessoa de Meia-Idade , Órbita/efeitos dos fármacos , Órbita/metabolismo , Transdução de Sinais/efeitos dos fármacos , Adulto Jovem
8.
Clin Nucl Med ; 46(8): 667-668, 2021 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-33782306

RESUMO

ABSTRACT: PET using 68Ga-labeled somatostatin receptor (SSTR) ligands adds significant information in meningioma patients. 18F-SiTATE is a novel, 18F-labeled SSTR-targeting peptide with remarkable imaging properties. Here, we present a 72-year-old woman with falx meningioma and transosseous extension. 18F-SiTATE PET/CT was performed 12 months after the previous 68Ga-DOTATOC PET/CT with comparable quantitative uptake and very good spatial resolution. So far, the widespread use of SSTR ligands for NET and meningioma imaging is hampered by cost-intensive 68Ge/68Ga generators, low activity amounts, lower spatial resolution, and short half-life. 18F-SiTATE might foster widespread use of SSTR ligands, overcoming the shortcomings of 68Ga-labeled ligands.


Assuntos
Neoplasias Meníngeas/diagnóstico por imagem , Meningioma/diagnóstico por imagem , Meningioma/metabolismo , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , Receptores de Somatostatina/metabolismo , Idoso , Feminino , Radioisótopos de Flúor/química , Humanos , Neoplasias Meníngeas/metabolismo
9.
Clin Nucl Med ; 46(5): 389-395, 2021 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-33782298

RESUMO

PURPOSE: This pilot study tested the principle that 177Lu-DOTATATE may be applied to patients with high-grade gliomas (HGGs) that are either inoperable or refractory to the standard conventional treatments and also assessed whether this approach could be a viable therapeutic plan in this dilemma. METHODS: In this prospective study, 16 subjects experiencing HGGs that were either inoperable or refractory to the standard conventional treatments were included. All the patients checked for somatostatin receptor expression on the tumors. The patients were treated with 1 to 4 cycles of IV 177Lu-DOTATATE. The primary end point was radiological response after peptide receptor radionuclide therapy, and the secondary end point was improved quality of life using Karnofsky Performance Score and Eastern Cooperative Oncology Group score. RESULTS: In total, 16 subjects (10 males and 6 females) with a mean age of 55.68 ± 13.17 years (26-73 years) participated in the study. Of them, 8 patients were new HGG cases, and 8 patients had recurrent tumors. The participants' responses to treatments were complete remission in 12.5% of (n = 2), partial remission in 31.25% (n = 5), disease stability in 18.7% (n = 3), and disease progression in 37.5% (n = 6). In total, pretreatment and posttreatment Karnofsky Performance Score and Eastern Cooperative Oncology Group scores did not improved (P > 0.05). The patients were followed up from 1 month to 26 months (median, 3 months). CONCLUSIONS: This preliminary result suggests that peptide receptor radionuclide therapy using 177Lu-DOTATATE may be associated with positive effects in patients with HGGs (grade III-IV). However, this approach should be evaluated in a more homogeneous group of patients with more favorable performance status.


Assuntos
Glioma/patologia , Glioma/radioterapia , Receptores de Somatostatina/metabolismo , Adulto , Idoso , Complexos de Coordenação/uso terapêutico , Estudos de Viabilidade , Feminino , Glioma/metabolismo , Humanos , Masculino , Pessoa de Meia-Idade , Gradação de Tumores , Octreotida/análogos & derivados , Octreotida/uso terapêutico , Compostos Organometálicos/uso terapêutico , Projetos Piloto , Estudos Prospectivos , Qualidade de Vida
10.
Clin Nucl Med ; 46(6): e336-e338, 2021 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-33661200

RESUMO

ABSTRACT: Solitary fibrous tumor of the pleura (SFTP) is a rare mesenchymal neoplasm. Preoperative diagnosis is usually difficult and based on radiological findings only. We report the imaging results observed in 5 patients with SFTP (2 malignant) obtained by 68Ga-DOTATOC PET/CT. At qualitative analysis, all tumors showed uptake of 68Ga-DOTATOC. Mean tumor SUVmax was 9.9 ± 5.7. The expression of SST2 (somatostatin receptors subtype 2) was confirmed by immunohistochemistry in 2 tumor samples, and by gene amplification of SST2 mRNA in all cases. These data suggest a diagnostic role of radioreceptor PET/CT in SFTP, and open novel potential treatment options in unresectable/metastatic disease.


Assuntos
Compostos Organometálicos , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , Tumor Fibroso Solitário Pleural/diagnóstico por imagem , Adulto , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Masculino , Pessoa de Meia-Idade , Receptores de Somatostatina/metabolismo , Tumor Fibroso Solitário Pleural/metabolismo , Tumor Fibroso Solitário Pleural/patologia
11.
Clin Nucl Med ; 46(7): 540-548, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-33782280

RESUMO

BACKGROUND: Recent evidence has demonstrated high expression of somatostatin receptors in neuroblastoma (NB) cells. Because of this, we endeavored to evaluate the diagnostic performance and clinical efficacy of 68Ga-DOTATATE PET/CT and peptide receptor radionuclide therapy (PRRT) using 177Lu-DOTATATE combined with chemotherapy in pediatric NB patients. PATIENTS AND METHODS: In total, 14 pediatric patients with histopathologically confirmed NB underwent 68Ga-DOTATATE PET/CT. Among them, the patients who were refractory or relapsed after therapy with 131I-MIBG and had intensive uptake of 68Ga-DOTATATE were referred for PRRT using 177Lu-DOTATATE. Treatment response based on follow-up imaging was classified into complete response, partial response, stable disease, and progressive disease. After each cycle of PRRT, laboratory tests were performed for evaluation of hematological, renal, and hepatic toxicities. The CTCAE (Common Terminology Criteria for Adverse Events; version 4.03) was used for grading adverse event. Curie score and International Society of Pediatric Oncology Europe Neuroblastoma score were used for semiquantitative analysis of scans of patients who underwent PRRT. In addition, overall survival was calculated as the time interval between the date of the first cycle and the end of follow-up or death. RESULTS: Overall, 14 refractory NB children including 7 boys and 7 girls with a median age of 5.5 years (ranged from 4 to 9) underwent 68Ga-DOTATATE PET/CT. PET/CT was positive in 10/14 patients (71.4%), and the median number of detected lesions in positive patients was 2 (range, 1-13). Of 14 patients, 5 patients underwent PRRT, including 3 boys and 2 girls. A total of 19 PRRT cycles and 66.4 GBq 177Lu-DOTATATE were given. Among these 5 patients, 2 showed an initial complete response, which relapsed a few months later, 1 showed a partial response, and 2 showed progressive disease. According to the Kaplan-Meier test, the overall survival was estimated at 14.5 months (95% confidence interval, 8.9-20.1). In evaluation of PRRT-related toxicity according to the CTCAE, 4 patients showed grade 1, and 1 showed grade 2 leukopenia. Two patients showed grade 1, and 2 others showed grade 2 anemia. Two patients showed grade 1, and 3 patients showed grade 2 thrombocytopenia. Serum creatinine in 1 patient increased to grade 1. CONCLUSIONS: Combination of 177Lu-DOTATATE with chemotherapeutic agents might achieve worthwhile responses with low toxicity, encouraging survival in NB patients who have relapsed or are refractory to conventional therapy, including 131I-MIBG therapy. Imaging with 68Ga-DOTATATE PET/CT in such patients has a relatively high detection efficacy, demonstrating its potential use as an alternative imaging tool to conventional modalities such as 123I/131I-MIBG. However, further well-designed trials are highly warranted.


Assuntos
Radioisótopos do Iodo/uso terapêutico , Neuroblastoma/patologia , Neuroblastoma/terapia , Receptores de Peptídeos/metabolismo , Criança , Pré-Escolar , Terapia Combinada , Complexos de Coordenação , Estudos de Viabilidade , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Neuroblastoma/tratamento farmacológico , Neuroblastoma/radioterapia , Octreotida/análogos & derivados , Compostos Organometálicos , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , Receptores de Somatostatina/metabolismo , Recidiva , Falha de Tratamento
12.
Mol Cell Endocrinol ; 527: 111226, 2021 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-33675866

RESUMO

Pancreatic neuroendocrine tumors (Pan-NETs), are heterogeneous neoplasms, whose incidence and prevalence are increasing worldwide. Pan-NETs are characterized by the expression of somatostatin receptors (SSTs). In particular, SST2 is the most widely distributed SST in NETs, thus representing the main molecular target for somatostatin analogs (SSAs). SSAs are currently approved for the treatment of well-differentiated NETs, and radionuclide-labeled SSAs are used for diagnostic and treatment purposes. SSAs, by binding to SSTs, have been shown to inhibit hormone secretion and thus provide control of hypersecretion symptoms, when present, and inhibit tumor proliferation. After SSA binding to SST2, the fate of the receptor is determined by trafficking mechanisms, crucial for the response to endogenous or pharmacological ligands. Although SST2 acts mostly through G protein-dependent mechanism, receptor-ligand complex endocytosis and receptor trafficking further regulate its function. SST2 mediates the decrease of hormone secretion via a G protein-dependent mechanism, culminating with the inhibition of adenylyl cyclase and calcium channels; it also inhibits cell proliferation and increases apoptosis through the modulation of protein tyrosine phosphatases. Moreover, SST2 inhibits angiogenesis and cell migration. In this respect, the cross-talk between SST2 and its interacting proteins, including Filamin A (FLNA) and aryl hydrocarbon receptor-interacting protein (AIP), plays a crucial role for SST2 signaling and responsiveness to SSAs. This review will focus on recent studies from our and other groups that have investigated the trafficking and signaling of SST2 in Pan-NETs, in order to provide insights into the mechanisms underlying tumor responsiveness to pharmacological treatments.


Assuntos
Movimento Celular , Proliferação de Células , Proteínas de Neoplasias/metabolismo , Tumores Neuroendócrinos/metabolismo , Neoplasias Pancreáticas/metabolismo , Receptores de Somatostatina/metabolismo , Transdução de Sinais , Apoptose/genética , Humanos , Proteínas de Neoplasias/genética , Neovascularização Patológica/genética , Neovascularização Patológica/metabolismo , Neovascularização Patológica/terapia , Tumores Neuroendócrinos/irrigação sanguínea , Tumores Neuroendócrinos/genética , Tumores Neuroendócrinos/terapia , Neoplasias Pancreáticas/irrigação sanguínea , Neoplasias Pancreáticas/genética , Neoplasias Pancreáticas/terapia , Receptores de Somatostatina/genética
13.
J Cell Physiol ; 236(10): 6974-6987, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-33682941

RESUMO

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 fármacos
14.
J Cancer Res Clin Oncol ; 147(5): 1335-1340, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33598797

RESUMO

BACKGROUND: Treatment regimens for patients with metastatic or recurrent post-radiation, locoregional, unresectable salivary cancer are limited. An inverse correlation between somatostatin receptor 2 (SSTR2) and the proliferating marker Ki-67 in neuroendocrine tumors has enabled a treatment plan for metastatic disease, utilizing peptide receptor radionuclide therapy. Interestingly, healthy salivary glands express high levels of SSTR2. In this study, the presence of SSTR2, its correlation with Ki-67 in glandular salivary carcinomas and the clinical applicability thereof was determined. METHODS: In the retrospective part of this study, 76 adequate tumor tissue specimens obtained from patients diagnosed with primary or metastatic salivary carcinomas between 1988 and 2016, were collected for tissue array and histologically classified. Immunohistochemistry was performed to determine the presence, relative expression and potential correlation of SSTR2 and Ki-67. The clinical significance of SSTR2 expression was determined by prospectively assessing 68Ga-DOTATATE uptake using PET-CT imaging, in patients diagnosed with metastatic salivary gland malignant tumors between 2015 and 2016. RESULTS: Sixty-three primary cancer tumors and 14 metastatic tumors were tested. All tumor subtypes were found to express SSTR2 to some extent. The highest expression was seen in Mucoepidermoid carcinoma (MEC) tissues where the majority of specimens (86.4%) expressed SSTR2. A relatively strong immunohistochemical staining score for SSTR2 was observed in MEC, adenoid cystic carcinoma and polymorphous adenocarcinoma. Interestingly, an inverse correlation between SSTR2 and Ki-67 expressions was observed (44%) in MEC tissue. Uptake of 68Ga-DOTATATE was visualized using PET-CT imaging in 40% of patients, across metastatic MEC and ACC. All observations were found to be statistically significant. CONCLUSION: This study confirms the expression of SSTR2 in glandular salivary carcinomas and an inverse correlation in expression levels between SSTR2 and Ki-67. This lays a foundation for novel treatment options in salivary metastatic cancers where SSTR2 may be a potential novel therapeutic target.


Assuntos
Receptores de Somatostatina/metabolismo , Neoplasias das Glândulas Salivares/metabolismo , Glândulas Salivares/metabolismo , Adenocarcinoma/metabolismo , Carcinoma Adenoide Cístico/metabolismo , Carcinoma Mucoepidermoide/metabolismo , Feminino , Humanos , Imuno-Histoquímica/métodos , Antígeno Ki-67/metabolismo , Masculino , Recidiva Local de Neoplasia/metabolismo , Octreotida/análogos & derivados , Octreotida/metabolismo , Compostos Organometálicos/metabolismo , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada/métodos , Compostos Radiofarmacêuticos/metabolismo , Estudos Retrospectivos
15.
Nat Commun ; 12(1): 117, 2021 01 05.
Artigo em Inglês | MEDLINE | ID: mdl-33402692

RESUMO

Nasopharyngeal cancer (NPC), endemic in Southeast Asia, lacks effective diagnostic and therapeutic strategies. Even in high-income countries the 5-year survival rate for stage IV NPC is less than 40%. Here we report high somatostatin receptor 2 (SSTR2) expression in multiple clinical cohorts comprising 402 primary, locally recurrent and metastatic NPCs. We show that SSTR2 expression is induced by the Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1) via the NF-κB pathway. Using cell-based and preclinical rodent models, we demonstrate the therapeutic potential of SSTR2 targeting using a cytotoxic drug conjugate, PEN-221, which is found to be superior to FDA-approved SSTR2-binding cytostatic agents. Furthermore, we reveal significant correlation of SSTR expression with increased rates of survival and report in vivo uptake of the SSTR2-binding 68Ga-DOTA-peptide radioconjugate in PET-CT scanning in a clinical trial of NPC patients (NCT03670342). These findings reveal a key role in EBV-associated NPC for SSTR2 in infection, imaging, targeted therapy and survival.


Assuntos
Infecções por Vírus Epstein-Barr/genética , Regulação Neoplásica da Expressão Gênica , Carcinoma Nasofaríngeo/genética , Neoplasias Nasofaríngeas/genética , Recidiva Local de Neoplasia/genética , Receptores de Somatostatina/genética , Proteínas da Matriz Viral/genética , Animais , Antineoplásicos/farmacologia , Linhagem Celular Tumoral , Infecções por Vírus Epstein-Barr/tratamento farmacológico , Infecções por Vírus Epstein-Barr/mortalidade , Infecções por Vírus Epstein-Barr/virologia , Feminino , Herpesvirus Humano 4/efeitos dos fármacos , Herpesvirus Humano 4/crescimento & desenvolvimento , Herpesvirus Humano 4/patogenicidade , Interações Hospedeiro-Patógeno/genética , Humanos , Metástase Linfática , Masculino , Camundongos , Camundongos Nus , Terapia de Alvo Molecular , NF-kappa B/genética , NF-kappa B/metabolismo , Carcinoma Nasofaríngeo/tratamento farmacológico , Carcinoma Nasofaríngeo/mortalidade , Carcinoma Nasofaríngeo/virologia , Neoplasias Nasofaríngeas/tratamento farmacológico , Neoplasias Nasofaríngeas/mortalidade , Neoplasias Nasofaríngeas/virologia , Recidiva Local de Neoplasia/tratamento farmacológico , Recidiva Local de Neoplasia/mortalidade , Recidiva Local de Neoplasia/virologia , Octreotida/farmacologia , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , Receptores de Somatostatina/antagonistas & inibidores , Receptores de Somatostatina/metabolismo , Transdução de Sinais , Análise de Sobrevida , Proteínas da Matriz Viral/antagonistas & inibidores , Proteínas da Matriz Viral/metabolismo , Ensaios Antitumorais Modelo de Xenoenxerto
16.
J Cell Mol Med ; 25(5): 2484-2492, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33491286

RESUMO

In somatotroph pituitary tumours, somatostatin analogue (SSA) therapy outcomes vary throughout the studies. We performed an analysis of cohort of patients with acromegaly from the Czech registry to identify new prognostic and predictive factors. Clinical data of patients were collected, and complex immunohistochemical assessment of tumour samples was performed (SSTR1-5, dopamine D2 receptor, E-cadherin, AIP). The study included 110 patients. In 31, SSA treatment outcome was evaluated. Sparsely granulated tumours (SGST) differed from the other subtypes in expression of SSTR2A, SSTR3, SSTR5 and E-cadherin and occurred more often in young. No other clinical differences were observed. Trouillas grading system showed association with age, tumour size and SSTR2A expression. Factors significantly associated with SSA treatment outcome included age, IGF1 levels, tumour size and expression of E-cadherin and SSTR2A. In the group of SGST, poor SSA response was observed in younger patients with larger tumours, lower levels of SSTR2A and higher Ki67. We observed no relationship with expression of other proteins including AIP. No predictive value of E-cadherin was observed when tumour subtype was considered. Multiple additional factors apart from SSTR2A expression can predict treatment outcome in patients with acromegaly.


Assuntos
Acromegalia/complicações , Acromegalia/genética , Caderinas/genética , Regulação da Expressão Gênica , Neoplasias Hipofisárias/diagnóstico , Neoplasias Hipofisárias/etiologia , Receptores de Somatostatina/genética , Acromegalia/metabolismo , Adulto , Biomarcadores , Tomada de Decisão Clínica , Terapia Combinada , Gerenciamento Clínico , Feminino , Humanos , Imuno-Histoquímica , Masculino , Pessoa de Meia-Idade , Neoplasias Hipofisárias/terapia , Prognóstico , Isoformas de Proteínas , Curva ROC , Receptores de Somatostatina/metabolismo , Resultado do Tratamento , Adulto Jovem
17.
Theranostics ; 11(2): 491-505, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33391488

RESUMO

Patients with neuroendocrine tumors (NETs) can be treated with peptide receptor radionuclide therapy (PRRT). Here, the somatostatin analogue octreotate radiolabeled with lutetium-177 is targeted to NET cells by binding to the somatostatin receptor subtype 2 (SST2). During radioactive decay, DNA damage is induced, leading to NET cell death. Although the therapy proves to be effective, mortality rates remain high. To appropriately select more optimal treatment strategies, it is essential to first better understand the radiobiological responses of tumor cells to PRRT. Methods: We analyzed PRRT induced radiobiological responses in SST2 expressing cells and xenografted mice using SPECT/MRI scanning and histological and molecular analyses. We measured [177Lu]Lu-DOTA-TATE uptake and performed analyses to visualize induction of DNA damage, cell death and other cellular characteristics. Results: The highest accumulation of radioactivity was measured in the tumor and kidneys. PRRT induced DNA damage signaling and repair in a time-dependent manner. We observed intra-tumor heterogeneity of DNA damage and apoptosis, which was not attributed to proliferation or bioavailability. We found a strong correlation between high DNA damage levels and high SST2 expression. PRRT elicited a different therapeutic response between models with different SST2 expression levels. Heterogeneous SST2 expression levels were also confirmed in patient NETs. Conclusion: Heterogeneous SST2 expression levels within NETs cause differentially induced DNA damage levels, influence recurrent tumor phenotypes and impact the therapeutic response in different models and potentially in patients. Our results contribute to a better understanding of PRRT effects, which might impact future therapeutic outcome of NET patients.


Assuntos
Complexos de Coordenação/uso terapêutico , Octreotida/análogos & derivados , Neoplasias Pancreáticas/radioterapia , Compostos Radiofarmacêuticos/uso terapêutico , Receptores de Somatostatina/metabolismo , Animais , Apoptose , Proliferação de Células , Complexos de Coordenação/farmacocinética , Humanos , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Octreotida/farmacocinética , Octreotida/uso terapêutico , Neoplasias Pancreáticas/metabolismo , Neoplasias Pancreáticas/patologia , Compostos Radiofarmacêuticos/farmacocinética , Distribuição Tecidual , Tomografia Computadorizada de Emissão de Fóton Único , Células Tumorais Cultivadas , Ensaios Antitumorais Modelo de Xenoenxerto
18.
Mol Cell Endocrinol ; 524: 111159, 2021 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-33428965

RESUMO

Somatostatin receptor type 5 (SST5) represents the main pharmacological target in the treatment of adrenocorticotroph hormone (ACTH)-secreting tumors. However, molecular predictors of responsiveness to pasireotide require further investigation. The cytoskeleton protein filamin A (FLNA) modulates the responsiveness to somatostatin analogs (SSA) treatment in other types of pituitary tumors by regulating somatostatin receptor type 2 (SST2)/dopamine receptor type 2 (DRD2) expression and activity. Here, we aimed to test the involvement of FLNA in the modulation of SST5 response to SSA in human and murine tumor corticotrophs. Western blot analysis of human corticotropinomas showed that FLNA and SST5 correlate. Both in human primary cultures and AtT-20 cells, FLNA genetic silencing caused a decrease of receptor expression level. Moreover, pasireotide-mediated SST5 downregulation observed in AtT-20 control cells was no further detected in FLNA silenced cells. In AtT-20 cells, in situ PLA experiments revealed an increased number of SST5-FLNA complexes following pasireotide incubation. Finally, FLNA knock down abolished pasireotide-induced SST5 actions on hormone secretion, cell proliferation and apoptosis. In conclusion, FLNA is implicated in SST5 expression modulation and signaling.


Assuntos
Corticotrofos/metabolismo , Filaminas/metabolismo , Neoplasias Hipofisárias/metabolismo , Receptores de Somatostatina/metabolismo , Transdução de Sinais , Somatostatina/análogos & derivados , Animais , Apoptose , Linhagem Celular Tumoral , Proliferação de Células , Inativação Gênica , Hormônios/metabolismo , Humanos , Camundongos , Ligação Proteica , Somatostatina/metabolismo
19.
Mol Neurobiol ; 58(5): 2107-2117, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33411247

RESUMO

Somatostatin (SST) and its analogues like octreotide (OCT) have analgesic effect on a variety of pain through peripheral SST receptors (SSTRs). However, the precise molecular mechanisms have not yet been fully elucidated. This research aimed to identify possible antinociceptive mechanisms, showing functional links of the SSTR2 and acid-sensing ion channels (ASICs). Herein, we reported that OCT inhibited the electrophysiological activity of ASICs in rat dorsal root ganglia (DRG) neurons. OCT concentration-dependently decreased the peak amplitude of acid-evoked inward currents, which were mediated by ASICs. OCT shifted concentration-response curve to protons downwards, with a decrease of 36.53 ± 5.28% in the maximal current response to pH 4.5 in the presence of OCT. OCT inhibited ASIC-mediated currents through SSTR2, since the inhibition was blocked by Cyn 154806, a specific SSTR2 antagonist. The OCT inhibition of ASIC-mediated currents was mimicked by H-89, a membrane-permeable inhibitor of PKA, and reversed by internal treatment of an adenylyl cyclase activator forskolin or 8-Br-cAMP. OCT also decreased the number of action potentials induced by acid stimuli through SSTR2. Finally, peripheral administration of 20 µM OCT, but not 2 µM OCT, significantly relieved nociceptive responses to intraplantar injection of acetic acid in rats. This occurred through local activation of SSTR2 in the injected hindpaw and was reversed following co-application of Cyn 154806. Our results indicate that activation SSTR2 by OCT can inhibit the activity of ASICs via an intracellular cAMP and PKA signaling pathway in rat DRG neurons. These observations demonstrate a cross-talk between ASICs and SSTR2 in peripheral sensory neurons, which was a novel peripheral analgesic mechanism of SST and its analogues.


Assuntos
Canais Iônicos Sensíveis a Ácido/metabolismo , Gânglios Espinais/efeitos dos fármacos , Octreotida/farmacologia , Receptores de Somatostatina/metabolismo , Células Receptoras Sensoriais/efeitos dos fármacos , Ácido Acético/farmacologia , Potenciais de Ação/efeitos dos fármacos , Animais , Relação Dose-Resposta a Droga , Gânglios Espinais/metabolismo , Masculino , Nociceptividade/efeitos dos fármacos , Oligopeptídeos/farmacologia , Limiar da Dor/efeitos dos fármacos , Técnicas de Patch-Clamp , Ratos , Ratos Sprague-Dawley , Células Receptoras Sensoriais/metabolismo , Transdução de Sinais/efeitos dos fármacos
20.
Diabetes ; 70(2): 423-435, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33154069

RESUMO

The aim for this study was to elucidate how the hypothalamic hunger-inducing hormone acyl-ghrelin (AG), which is also produced in the pancreas, affects ß-cell function, with particular attention to the role of ATP-sensitive K+ (KATP) channels and the exact site of action of the hormone. AG hyperpolarized the membrane potential and decreased cytoplasmic calcium concentration [Ca2+]c and glucose-stimulated insulin secretion (GSIS). These effects were abolished in ß-cells from SUR1-knockout (KO) mice. AG increased KATP current but only in a configuration with intact metabolism. Unacylated ghrelin counteracted the effects of AG. The influence of AG on membrane potential and GSIS could only be averted in the combined presence of a ghrelin receptor (GHSR1a) antagonist and an inverse agonist. The inhibition of GSIS by AG could be prevented by dibutyryl cyclic-cAMP or 3-isobutyl-1-methylxanthine and the somatostatin (SST) receptor 2-5 antagonist H6056. These data indicate that AG indirectly opens KATP channels probably by interference with the cAMP/cAMP-dependent protein kinase pathway, resulting in a decrease of [Ca2+]c and GSIS. The experiments with SUR1-KO ß-cells point to a direct effect of AG on ß-cells and not, as earlier suggested, to an exclusive effect by AG-induced SST release from δ-cells. Nevertheless, SST receptors may be involved in the effect of AG, possibly by heteromerization of AG and SST receptors.


Assuntos
Grelina/análogos & derivados , Secreção de Insulina/efeitos dos fármacos , Células Secretoras de Insulina/efeitos dos fármacos , Canais KATP/metabolismo , Animais , Cálcio/metabolismo , Grelina/farmacologia , Glucose/farmacologia , Células Secretoras de Insulina/metabolismo , Camundongos , Receptores de Somatostatina/metabolismo , Transdução de Sinais/efeitos dos fármacos , Somatostatina/metabolismo
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