La ruta de señalización WNT en la determinación de progenitores pancreáticos

1 página. IX Jornadas Andaluzas Salud Investiga. Cádiz 20-22 octubre, 2010.Nuestro laboratorio trata de determinar los mecanismos moleculares implicados en la formación de los distintos tipos celulares pancreáticos adultos a partir de células progenitoras. Este conocimiento es fundamental para comprender las bases de enfermedades tan terribles como el cáncer pancreático. Además, es absolutamente necesario para el desarrollo de protocolos de formación in vitro de células beta productoras de insulina, una atractiva estrategia terapéutica para la diabetes. A este respecto, el papel de la ruta de señalización embrionaria Wnt parece ser importante ya que estudios previos han demostrado que la activación de esta ruta es necesaria para la formación de células pancreáticas a partir de células embrionarias. En nuestro proyecto nos hemos planteado determinar el efecto de la ruta Wnt sobre la formación de páncreas sobreactivando dicha ruta en progenitores pancreáticos en el ratón.Peer reviewe

Neurocognitive Function in Acromegaly after Surgical Resection of GH-Secreting Adenoma versus Naïve Acromegaly

Patients with active untreated acromegaly show mild to moderate neurocognitive disorders that are associated to chronic exposure to growth hormone (GH) and insulin-like growth factor (IGF-I) hypersecretion. However, it is unknown whether these disorders improve after controlling GH/IGF-I hypersecretion. The aim of this study was to compare neurocognitive functions of patients who successfully underwent GH-secreting adenoma transsphenoidal surgery (cured patients) with patients with naive acromegaly. In addition, we wanted to determine the impact of different clinical and biochemical variables on neurocognitive status in patients with active disease and after long-term cure. A battery of six standardized neuropsychological tests assessed attention, memory and executive functioning. In addition, a quantitative electroencephalography with Low-Resolution Electromagnetic Tomography (LORETA) solution was performed to obtain information about the neurophysiological state of the patients. Neurocognitive data was compared to that of a healthy control group. Multiple linear regression analysis was also conducted using clinical and hormonal parameters to obtain a set of independent predictors of neurocognitive state before and after cure. Both groups of patients scored significantly poorer than the healthy controls on memory tests, especially those assessing visual and verbal recall. Patients with cured acromegaly did not obtain better cognitive measures than naïve patients. Furthermore memory deficits were associated with decreased beta activity in left medial temporal cortex in both groups of patients. Regression analysis showed longer duration of untreated acromegaly was associated with more severe neurocognitive complications, regardless of the diagnostic group, whereas GH levels at the time of assessment was related to neurocognitive outcome only in naïve patients. Longer duration of post-operative biochemical remission of acromegaly was associated with better neurocognitive state. Overall, this data suggests that the effects of chronic exposure to GH/IGF-I hypersecretion could have long-term effects on brain functions. © 2013 Martín-Rodríguez et al.Funding for this project was provided by an R&D grant from Novartis Oncology and the Plan Andaluz de Investigación (CTS-444). DAC was supported by the “Ramón y Cajal” program (RYC-2006-001071) of the Spanish Ministry of Science and Innovation.Peer Reviewe

Genetically Engineered Mouse Models of Pituitary Tumors

Animal models constitute valuable tools for investigating the pathogenesis of cancer as well as for preclinical testing of novel therapeutics approaches. However, the pathogenic mechanisms of pituitary-tumor formation remain poorly understood, particularly in sporadic adenomas, thus, making it a challenge to model pituitary tumors in mice. Nevertheless, genetically engineered mouse models (GEMMs) of pituitary tumors have provided important insight into pituitary tumor biology. In this paper, we review various GEMMs of pituitary tumors, highlighting their contributions and limitations, and discuss opportunities for research in the field.David A. Cano was supported by the grants from the Spanish Ministry of Science and Innovation (SAF2011-26805) and Andalusian Regional Ministry of Science and Innovation (CTS-7478). Alfonso Leal-Cerro was supported by a grant from the Spanish Ministry of Health, ISCIII (PI12/0143). Alfonso Soto-Moreno was supported by a grant from the Spanish Ministry of Health, ISCIII (PI12/02043).Peer reviewedPeer Reviewe

Rationale and design of PATRO Adults, a multicentre, noninterventional study of the long-term efficacy and safety of Omnitrope for the treatment of adult patients with growth hormone deficiency

Objective : To describe the rationale and design of PATRO Adults, a postmarketing surveillance study of the long-term efficacy and safety of somatropin (Omnitrope ® ) for the treatment of adult patients with growth hormone deficiency (GHD). Methods : PATRO Adults is an observational, multicentre, open, longitudinal, noninterventional study being conducted in hospitals and specialized endocrinology clinics across several European countries. The primary objective is to assess the safety and efficacy of Omnitrope ® in adults treated in routine clinical practice. Eligible patients are male or female adults who are receiving treatment with Omnitrope ® and who have provided informed consent. Patients who have been treated with another human growth hormone (hGH) product before starting Omnitrope ® therapy will also be eligible for inclusion. Efficacy assessments will be based on the analysis of the following: insulin-like growth factor-1 levels within age- and gender-adjusted normal ranges; anthropometric measures (weight, waist circumference, total fat mass, lean body mass, total body water); bone mineral density; lipids; effects on cardiovascular risk factors such as glucose metabolism, blood pressure and inflammatory markers (e.g. C-reactive protein); and quality of life. All adverse events will be monitored and recorded. Particular emphasis will be placed on long-term safety, the recording of malignancies, the occurrence and clinical impact of antirecombinant hGH antibodies, the incidence, severity and duration of hyperglycaemia, and the development of diabetes during treatment with Omnitrope ® . Conclusions: PATRO Adults is a large, long-term, postmarketing surveillance study that will extend the safety database for Omnitrope ® , as well as contributing to the available data for all recombinant hGH products. Of particular interest, the study will provide important data on the impact of long-term GH replacement therapy on the development of diabetes mellitus, the recurrence/regrowth of hypothalamic–pituitary tumours, and de novo malignancy or recurrence of other (non-hypothalamic–pituitary) tumours

Molecular characterization of an animal model of acromegaly induced by implantation of GC somatotroph tumor cell line

Resumen del póster presentado al "8th International Congress of Neuroendocrinology" celebrado en Sydney (Australia) del 17 al 20 de agosto de 2014.-- et al.Subcutaneous implantation of GH-producing GC cells in female Wisth-Furth rats results in acromegalic phenotype (i.e. gigantism, visceromegaly, etc.). This animal model of acromegaly has been known for almost two decades and largely used to study the effects of chronic GH exposure on target tissues. However, little is known about the kinetics of tumor cell growth and information at the molecular level is scarce. In the current work Immunochemistry, molecular biology and imaging techniques were used to analyze in detail this animal model of acromegaly. GC cells (1 X 107) were injected sc into the flank of 7-week-old female rats. Control rats were injected sc with saline. Animals were weighed weekly. Tumors became palpable 2–3 weeks after implantation. For in vivo assessment of tumor growth and metabolism, microPET scans with 18F-FDG and [11C]Met were conducted at 1, 2, 4 and 8 weeks after implantation. After 20 weeks all animals were sacrificed and tumor samples were collected for further analysis. Immunohistochemical and quantitative real-time PCR analysis was conducted on tumor samples. A 1.5-2 fold increase in glucose uptake and [11C]Met accumulation was localized in the site of injection at 1 week after implantation, as compared to saline-treated rats. Highest peaks of these radiotracers at this site were found at 2 weeks after implantation. At 4 weeks, microPET scans clearly revealed evidence of tumor necrosis. Resected tumors were found to be exclusively GH-producing cells with no evidence of activation of other pituitary hormones. Analysis of somatostatin receptor expression revealed that sst2 was highly expressed followed by sst1. sst3 and sst5 were virtually absent in all samples analyzed. GHR and GHRHR were also present in the experimental tumors. Tumor cells displayed marked b-catenin and N-cadherin levels, showing a similar pattern to that found in normal pituitary, a finding consistent with the low metastastic potential of the somatotroph tumors. Interestingly, tumor cells expressed Sox2 and Sox9, two markers of pituitary progenitor cells. Altogether, our results show molecular similarities between GC-implanted tumors and human somatotroph adenomas. Thus, subcutaneous injection of GC cells might be a useful model to study the mechanisms of somatotroph adenoma tumorigenesis as well as to evaluate compounds for in vivo antitumoral activity.Peer Reviewe

GDNF is required for neural colonization of the pancreas

The mammalian pancreas is densely innervated by both the sympathetic and parasympathetic nervous systems, which control exocrine and endocrine secretion. During embryonic development, neural crest cells migrating in a rostrocaudal direction populate the gut, giving rise to neural progenitor cells. Recent studies in mice have shown that neural crest cells enter the pancreatic epithelium at E11.5. However, the cues that guide the migration of neural progenitors into the pancreas are poorly defined. In this study we identify glial cell line-derived neurotrophic factor (GDNF) as a key player in this process. GDNF displays a dynamic expression pattern during embryonic development that parallels the chronology of migration and differentiation of neural crest derivatives in the pancreas. Conditional inactivation of Gdnf in the pancreatic epithelium results in a dramatic loss of neuronal and glial cells and in reduced parasympathetic innervation in the pancreas. Importantly, the innervation of other regions of the gut remains unaffected. Analysis of Gdnf mutant mouse embryos and ex vivo experiments indicate that GDNF produced in the pancreas acts as a neurotrophic factor for gut-resident neural progenitor cells. Our data further show that exogenous GDNF promotes the proliferation of pancreatic progenitor cells in organ culture. In summary, our results point to GDNF as crucial for the development of the intrinsic innervation of the pancreas.D.A.C. was supported by the Ramón y Cajal program [RYC-2006-001071] and by grants from the Spanish Ministry of Science and Innovation [SAF2008-02469 and SAF2011-26805] and the Andalusian Regional Ministry of Health [PI-0250/2008]. A.L.-C. was supported by grants from the Andalusian Regional Government [P08-CVI-3727 and CTS-444]. A.P. was supported by grants from the Spanish Ministry of Science and Innovation [SAF2009-06977] and the Andalusian Regional Government [CTS-3560]. J.L.-B. was supported by the Botín Foundation, CIBERNED, and the Spanish Ministries of Science (SAF Program) and Health.Peer Reviewe

A cellular and molecular basis for the selective desmopressin-induced ACTH release in cushing disease patients: Key role of AVPR1b receptor and potential therapeutic implications

Luque, Raúl M. et al.[Context] Desmopressin is a synthetic agonist of vasopressin receptors (AVPRs). The desmopressin stimulation test is used in the diagnosis and postsurgery prognosis of Cushing disease (CD). However, the cellular and molecular mechanisms underlying the desmopressin-induced ACTH increase in patients with CD are poorly understood. [Objective] The objectives of this study were to determine, for the first time, whether desmopressin acts directly and exclusively on pituitary corticotropinoma cells to stimulate ACTH expression/release and to elucidate the cellular and molecular mechanisms involved in desmopressin-induced ACTH increase in CD.[Design] A total of 8 normal pituitaries (NPs), 23 corticotropinomas, 14 nonfunctioning pituitary adenomas, 17 somatotropinomas, and 3 prolactinomas were analyzed for AVPR expression by quantitative real-time RT-PCR. Primary cultures derived from corticotropinomas, nonfunctioning pituitary adenomas, somatotropinomas, prolactinomas, and NPs were treated with desmopressin, and ACTH secretion/expression, [Ca2+]i kinetics, and AVPR expression and/or proliferative response were evaluated. The relationship between AVPR expression and plasma adrenocorticotropin/cor-tisol levels obtained from desmopressin tests was assessed.[Results] Desmopressin affects all functional parameters evaluated in corticotropinoma cells but not in NPs or other pituitary adenomas cells. These effects might be due to the dramatic elevation of AVPR1b expression levels found in corticotropinomas. In line with this notion, the use of an AVPR1b antagonist completely blocked desmopressin stimulatory effects. Remarkably, only AVPR1b expression was positively correlated with elevated plasma adrenocorticotropin levels in corticotropinomas.[Conclusions] The present results provide a cellular and molecular basis to support the desmopressin stimulation test as a reliable, specific test for the diagnosis and postsurgery prognosis of CD. Furthermore, our data indicate that AVPR1b is responsible for the direct/exclusive desmopressin stimulatory pituitary effects observed in CD, thus opening the possibility of exploring AVPR1b antagonists as potential therapeutic tools for CD treatment. Copyright © 2013 by The Endocrine Society.Funding organizations are Junta de Andalucia, Ministerios de Economía y Competitividad y Sanidad, Servicios Sociales e Igualdad, Ciber, Merck Serono, ISCIII (Spain).Peer Reviewe

Rab18 is reduced in pituitary tumors cusing acromegaly and its overexpression reverts growth hormone hypersecretion

Context: Rab proteins regulate the sequential steps of intracellular membrane transport. Alterations of these GTPases and their associated proteins are emerging as the underlying cause for several human diseases involving dysregulated secretory activities. Objective: Herein we investigated the role of Rab18, which negatively regulates hormone secretion by interacting with secretory granules, in relation to the altered functioning of tumoral pituitary somatotropes causing acromegaly. Patients: A total of 18 patients diagnosed with pituitary tumors causing acromegaly (nine patients) or nonfunctioning adenomas (nine patients) underwent endoscopic transsphenoidal surgery. Adenomas were subsequently processed to evaluate Rab18 production in relation to GH secretion. Results: We found that somatotropinoma cells are characterized by a high secretory activity concomitantly with a remarkably reduced Rab18 expression (15%) and protein content levels (30%), as compared with cells from nonfunctioning pituitary adenomas derived from patients with normal or reduced GH plasma levels (100%). Furthermore, immunoelectron microscopy revealed that Rab18 association with the surface of GH-containing secretory granules was significantly lower in somatotropes from acromegalies than nonfunctioning pituitary adenomas. Finally, we provide evidence that modulation of Rab18 gene expression can revert substantially the hypersecretory activity of cells because Rab18 overexpression reduced by 40% the capacity of cells from acromegalies to respond to GHRH stimulation. Conclusion: These results suggest that molecular alterations affecting individual components of the secretory granule traffic machinery can contribute to maintain a high level of GH in plasma. Accordingly, Rab18 constitutes a valuable target as a diagnostic, prognostic, and/or therapeutic tool for human acromegaly