RESUMO
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
Acromegaly is a chronic systemic disease caused in the vast majority of cases by growth hormone (GH)-secreting adenoma, with surgery being the first-line treatment. When a cure is not attained with surgery, first-generation somatostatin receptor ligands (fg-SRLs) are the most common medication prescribed. Predictors of response to fg-SRLs have been studied; however, they cannot fully predict the response to fg-SRL. MicroRNAs are small RNAs, the main role of which is messenger RNA (mRNA) post-transcriptional regulation. This study aimed to identify the microRNAs involved in resistance to treatment with fg-SRLs in acromegaly. Ten patients with acromegaly undergoing treatment with fg-SRLs were selected to undergo miRNA sequencing: five controlled and five uncontrolled with treatment. Bioinformatic analysis was performed to detect differentially expressed miRNAs. Then, the same 10 samples were used for validation by qPCR and an additional 22 samples were analyzed, totaling 32 samples. e We found 59 differentially expressed miRNAs in the first analysis. miR-181a-5p and miR-181b-5p were downregulated, and miR-383-5p was upregulated in the uncontrolled group. Receiver operating characteristic (ROC) curve analysis of miR-383-5p showed an NPV of 84.3% and a PPV of 84.5%. In summary, miR-181a-5p, miR-181b-5p, and miR-383-5p are biomarkers of response to fg-SRLs, and they can be used individually or included in prediction models as tools to guide clinical decisions.
Assuntos
Acromegalia , MicroRNAs , Humanos , Acromegalia/genética , Receptores de Somatostatina/genética , MicroRNAs/genética , MicroRNAs/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
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
Melanin-concentrating hormone (MCH) is a ubiquitous vertebrate neuropeptide predominantly synthesized by neurons of the diencephalon that can act through two G protein-coupled receptors, called MCHR1 and MCHR2. The expression of Mchr1 has been investigated in both rats and mice, but its synthesis remains poorly described. After identifying an antibody that detects MCHR1 with high specificity, we employed immunohistochemistry to map the distribution of MCHR1 in the CNS of rats and mice. Multiple neurochemical markers were also employed to characterize some of the neuronal populations that synthesize MCHR1. Our results show that MCHR1 is abundantly found in a subcellular structure called the primary cilium, which has been associated, among other functions, with the detection of free neurochemical messengers present in the extracellular space. Ciliary MCHR1 was found in a wide range of areas, including the olfactory bulb, cortical mantle, striatum, hippocampal formation, amygdala, midline thalamic nuclei, periventricular hypothalamic nuclei, midbrain areas, and in the spinal cord. No differences were observed between male and female mice, and interspecies differences were found in the caudate-putamen nucleus and the subgranular zone. Ciliary MCHR1 was found in close association with several neurochemical markers, including tyrosine hydroxylase, calretinin, kisspeptin, estrogen receptor, oxytocin, vasopressin, and corticotropin-releasing factor. Given the role of neuronal primary cilia in sensing free neurochemical messengers in the extracellular fluid, the widespread distribution of ciliary MCHR1, and the diverse neurochemical populations who synthesize MCHR1, our data indicate that nonsynaptic communication plays a prominent role in the normal function of the MCH system.
Assuntos
Encéfalo/metabolismo , Cílios/metabolismo , Receptores de Somatostatina/biossíntese , Caracteres Sexuais , Animais , Cílios/genética , Feminino , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Ratos , Ratos Long-Evans , Ratos Sprague-Dawley , Receptores de Somatostatina/genéticaRESUMO
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
Filamin-A (FLNA) plays a crucial role in somatostatin receptor (sst) subtype-2 signaling in somatotropinomas. Our objective was to investigate the in vivo association between FLNA and sst2 expression, sst5 expression, dopamine receptor subtype-2 (D2) expression, somatostatin receptor ligand (SRL) responsiveness and tumor invasiveness in somatotropinomas. Quantitative real-time PCR was used to evaluate the absolute mRNA copy numbers of FLNA/sst2/sst5/D2 in 96 somatotropinomas. FLNA, sst2 and sst5 protein expression levels were also evaluated using immunohistochemistry. The Knosp-Steiner criteria were used to evaluate tumor invasiveness. Median FLNA, sst2, sst5 and D2 copy numbers were 4,244, 731, 156 and 3,989, respectively. Thirty-one of the 35 available tumors (89%) were immune positive for FLNA in the cytoplasm and membrane but not in the nucleus. FLNA and sst5 expression were positively correlated at the mRNA and protein levels (p < 0.001 and p = 0.033, respectively). FLNA was positively correlated with sst2 mRNA in patients who were responsive to SRL (p = 0.014, R = 0.659). No association was found between FLNA and tumor invasiveness. Our findings show that in somatotropinomas FLNA expression positively correlated with in vivo sst5 and D2 expression. Notably, FLNA was only correlated with sst2 in patients who were controlled with SRL. FLNA was not associated with tumor invasiveness.
Assuntos
Acromegalia/genética , Adenoma/tratamento farmacológico , Antineoplásicos/administração & dosagem , Filaminas/genética , Adenoma Hipofisário Secretor de Hormônio do Crescimento/tratamento farmacológico , Receptores de Dopamina D2/genética , Receptores de Somatostatina/genética , Acromegalia/etiologia , Acromegalia/metabolismo , Adenoma/complicações , Adenoma/genética , Adenoma/metabolismo , Adolescente , Adulto , Idoso , Antineoplásicos/uso terapêutico , Membrana Celular/genética , Membrana Celular/metabolismo , Núcleo Celular/genética , Núcleo Celular/metabolismo , Citoplasma/genética , Citoplasma/metabolismo , Feminino , Filaminas/metabolismo , Adenoma Hipofisário Secretor de Hormônio do Crescimento/complicações , Adenoma Hipofisário Secretor de Hormônio do Crescimento/genética , Adenoma Hipofisário Secretor de Hormônio do Crescimento/metabolismo , Humanos , Masculino , Pessoa de Meia-Idade , Octreotida/administração & dosagem , Octreotida/uso terapêutico , Peptídeos Cíclicos/administração & dosagem , Peptídeos Cíclicos/uso terapêutico , Receptores de Dopamina D2/metabolismo , Receptores de Somatostatina/metabolismo , Somatostatina/administração & dosagem , Somatostatina/análogos & derivados , Somatostatina/uso terapêutico , Carga Tumoral , Adulto JovemRESUMO
Neurons that utilize melanin-concentrating hormone (MCH) as neuromodulator are located in the lateral hypothalamus and incerto-hypothalamic area. These neurons project throughout the central nervous system and play a role in sleep regulation. With the hypothesis that the MCHergic system function would be modified by the time of the day as well as by disruptions of the sleep-wake cycle, we quantified in rats the concentration of MCH in the cerebrospinal fluid (CSF), the expression of the MCH precursor (Pmch) gene in the hypothalamus, and the expression of the MCH receptor 1 (Mchr1) gene in the frontal cortex and hippocampus. These analyses were performed during paradoxical sleep deprivation (by a modified multiple platform technique), paradoxical sleep rebound and chronic sleep restriction, both at the end of the active (dark) phase (lights were turned on at Zeitgeber time zero, ZT0) and during the inactive (light) phase (ZT8). We observed that in control condition (waking and sleep ad libitum), Mchr1 gene expression was larger at ZT8 (when sleep predominates) than at ZT0, both in frontal cortex and hippocampus. In addition, compared to control, disturbances of the sleep-wake cycle produced the following effects: paradoxical sleep deprivation for 96 and 120 h reduced the expression of Mchr1 gene in frontal cortex at ZT0. Sleep rebound that followed 96 h of paradoxical sleep deprivation increased the MCH concentration in the CSF also at ZT0. Twenty-one days of sleep restriction produced a significant increment in MCH CSF levels at ZT8. Finally, sleep disruptions unveiled day/night differences in MCH CSF levels and in Pmch gene expression that were not observed in control (undisturbed) conditions. In conclusion, the time of the day and sleep disruptions produced subtle modifications in the physiology of the MCHergic system.
Assuntos
Hormônios Hipotalâmicos/líquido cefalorraquidiano , Hormônios Hipotalâmicos/genética , Hipotálamo/metabolismo , Melaninas/líquido cefalorraquidiano , Hormônios Hipofisários/líquido cefalorraquidiano , Precursores de Proteínas/genética , Receptores de Somatostatina/genética , Privação do Sono/metabolismo , Sono REM , Animais , Lobo Frontal/metabolismo , Expressão Gênica , Hipocampo/metabolismo , Masculino , Ratos , Ratos WistarRESUMO
Methylation pattern is presented here for first time as a potential molecular marker of changes on SSTR2A and SHP-1(I) gene promoter related to breast and prostate carcinoma. Our results have shown low concordances with SSTR2A and methylated state in prostate cancer and moderate relationship with unmethylated CpG-27 in breast cancer. We found significant concordances for both cancers and SHP-1(I) unmethylation, and increased HER2 expression and SSTR2A methylation in breast cancer. Moreover, we found a correlation between methylation patterns of two genes in normal breast tissue. These data might assist to select subgroups of patients for the administration of alternative therapies.
Assuntos
Biomarcadores Tumorais/genética , Neoplasias da Mama/genética , Metilação de DNA , Neoplasias da Próstata/genética , Proteína Tirosina Fosfatase não Receptora Tipo 6/genética , Receptores de Somatostatina/genética , Idoso , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Regiões Promotoras Genéticas , Neoplasias da Próstata/metabolismo , Neoplasias da Próstata/patologia , Isoformas de Proteínas , Receptores de Somatostatina/metabolismoRESUMO
OBJECTIVE: To evaluate expression of somatostatin receptor subtypes 2 and 5 (SSTR 2 and 5) by RT/PCR and immunohistochemistry (IHC) in GH-secreting adenomas, seeking correlations with response to octreotide. METHODS: SSTR2 and 5 expression was tested by IHC (n=37), RT/PCR (n=36) or both (n=13) in GH-secreting adenomas from 60 patients with acromegaly who had undergone pituitary surgery; 36 had been treated preoperatively with octreotide LAR for 3-6 months, and were categorized as responders (achievement of GH <2.5ng/mL and a normal age-adjusted IGF-1), partial responders (GH and IGF-1 reduction >50% and >30%, respectively) or non-responders. IHC was performed on a tissue microarray using specific antibodies directed to the carboxyl terminus of SSTR2 and 5. RESULTS: SSTR5 was the predominantly expressed receptor subtype by both IHC and RT/PCR in all tumors tested, regardless of whether they came from octreotide-naïve, octreotide-responsive, or octreotide-resistant patients. Immunostaining was concentrated in the cytoplasm. Neither SSTR2 nor SSTR5 expression correlated with baseline or post-octreotide GH or IGF-1 levels or tumor volume by either method. The agreement rate between RT/PCR and IHC was 77% in all 13 adenomas in which both methods were used. CONCLUSION: Expression of these receptors does not guarantee an adequate response to somatostatin analogs; other functional aspects of this interaction, such as receptor homo- and heterodimerization, and the resulting signaling cascade, probably play a role in determining whether a patient will respond or not to these agents.