Translational research in pituitary tumours

Although effective treatment regimens (surgical resection, drug treatment with dopamine agonists or somatostatin analogues, radiotherapy) have been established for the therapy of most pituitary tumours, a considerable proportion of affected patients cannot completely cured due to incomplete resection or drug resistance. Moreover, even if hormone levels have been normalized, patients with hormone-secreting tumours still show persistent pathophysiological alterations in metabolic, cardiovascular or neuropsychiatric parameters and have an impaired quality of life. In this review reasons for the discrepancy between biochemical cure and incomplete recovery from tumour-associated comorbidities are discussed and the clinical management is delineated exemplarily for patients with acromegaly and Cushing's disease. In view of the development of additional treatment concepts for the treatment of pituitary adenomas we speculate about the relevance of RSUME as a potential target for the development of an anti-angiogenic therapy. Moreover, the role of BMP-4 which stimulates prolactinoma development through the Smad signalling cascade is described and its role as putative drug target for the treatment of prolactinomas is discussed. Regarding the well-known resistance of a part of somatotropinomas to somatostatin analogue treatment, recently identified mechanisms responsible for the drug resistance are summarized and ways to overcome them in future treatment concepts are presented. Concerning novel therapeutic options for patients with Cushing's disease the impact of retinoic acid, which is currently tested in clinical studies, is shown, and the action and putative therapeutic impact of silibinin to resolve glucocorticoid resistance in these patients is critically discussed.Fil: Stalla, Günter K. No especifíca;Fil: Dimopoulou, Christina. Technische Universitat München; AlemaniaFil: Jung Sievers, Caroline. No especifíca;Fil: Arzt, Eduardo Simon. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación en Biomedicina de Buenos Aires - Instituto Partner de la Sociedad Max Planck; ArgentinaFil: Paez Pereda, Marcelo. Max Planck Institut Fur Psychiatrie; AlemaniaFil: Theodoropoulou, Marily. Technische Universitat München; AlemaniaFil: Ciato, Denis. Technische Universitat München; AlemaniaFil: Renner, Ulrich. Max Planck Institut Fur Psychiatrie; Alemani

Co-Expression of Wild-Type P2X7R with Gln460Arg Variant Alters Receptor Function

The P2X7 receptor is a member of the P2X family of ligand-gated ion channels. A single-nucleotide polymorphism leading to a glutamine (Gln) by arginine (Arg) substitution at codon 460 of the purinergic P2X7 receptor (P2X7R) has been associated with mood disorders. No change in function (loss or gain) has been described for this SNP so far. Here we show that although the P2X7R-Gln460Arg variant per se is not compromised in its function, co-expression of wild-type P2X7R with P2X7R-Gln460Arg impairs receptor function with respect to calcium influx, channel currents and intracellular signaling in vitro. Moreover, co-immunoprecipitation and FRET studies show that the P2X7R-Gln460Arg variant physically interacts with P2X7R-WT. Specific silencing of either the normal or polymorphic variant rescues the heterozygous loss of function phenotype and restores normal function. The described loss of function due to co-expression, unique for mutations in the P2RX7 gene so far, explains the mechanism by which the P2X7R-Gln460Arg variant affects the normal function of the channel and may represent a mechanism of action for other mutations.Fil: Aprile García, Fernando. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Fisiología, Biología Molecular y Celular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación en Biomedicina de Buenos Aires - Instituto Partner de la Sociedad Max Planck; ArgentinaFil: Metzger, Michael W.. Max Planck Institute of Psychiatry; AlemaniaFil: Paez Pereda, Marcelo. Max Planck Institute of Psychiatry; AlemaniaFil: Stadler, Herbert. Affectis Pharmaceuticals; AlemaniaFil: Acuña, Matias. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación en Biomedicina de Buenos Aires - Instituto Partner de la Sociedad Max Planck; ArgentinaFil: Liberman, Ana Clara. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación en Biomedicina de Buenos Aires - Instituto Partner de la Sociedad Max Planck; ArgentinaFil: Senin, Sergio Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación en Biomedicina de Buenos Aires - Instituto Partner de la Sociedad Max Planck; ArgentinaFil: Gerez, Juan Atilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación en Biomedicina de Buenos Aires - Instituto Partner de la Sociedad Max Planck; ArgentinaFil: Hoijman, Esteban. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Microscopías Avanzadas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Refojo, Damian. Max Planck Institute of Psychiatry; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Mitkovski, Mišo. Max Planck Institute of Experimental Medicine; AlemaniaFil: Panhuysen, Markus. Affectis Pharmaceuticals; AlemaniaFil: Stühmer, Walter. Max Planck Institute of Experimental Medicine; AlemaniaFil: Holsboer, Florian. Max Planck Institute of Psychiatry; Alemania. HMNC Brain Health; AlemaniaFil: Deussing, Jan M.. Max Planck Institute of Psychiatry; AlemaniaFil: Arzt, Eduardo Simon. Max Planck Institute of Psychiatry; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación en Biomedicina de Buenos Aires - Instituto Partner de la Sociedad Max Planck; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Fisiología, Biología Molecular y Celular; Argentin

A Somatostatin Receptor Subtype-3 (SST3) Peptide Agonist Shows Antitumor Effects in Experimental Models of Nonfunctioning Pituitary Tumors

[Purpose] Somatostatin analogues (SSA) are efficacious and safe treatments for a variety of neuroendocrine tumors, especially pituitary neuroendocrine tumors (PitNET). Their therapeutic effects are mainly mediated by somatostatin receptors SST2 and SST5. Most SSAs, such as octreotide/lanreotide/pasireotide, are either nonselective or activate mainly SST2. However, nonfunctioning pituitary tumors (NFPTs), the most common PitNET type, mainly express SST3 and finding peptides that activate this particular somatostatin receptor has been very challenging. Therefore, the main objective of this study was to identify SST3-agonists and characterize their effects on experimental NFPT models.[Experimental Design] Binding to SSTs and cAMP level determinations were used to screen a peptide library and identify SST3-agonists. Key functional parameters (cell viability/caspase activity/chromogranin-A secretion/mRNA expression/intracellular signaling pathways) were assessed on NFPT primary cell cultures in response to SST3-agonists. Tumor growth was assessed in a preclinical PitNET mouse model treated with a SST3-agonist. [Results] We successfully identified the first SST3-agonist peptides. SST3-agonists lowered cell viability and chromogranin-A secretion, increased apoptosis in vitro, and reduced tumor growth in a preclinical PitNET model. As expected, inhibition of cell viability in response to SST3-agonists defined two NFPT populations: responsive and unresponsive, wherein responsive NFPTs expressed more SST3 than unresponsive NFPTs and exhibited a profound reduction of MAPK, PI3K-AKT/mTOR, and JAK/STAT signaling pathways upon SST3-agonist treatments. Concurrently, SSTR3 silencing increased cell viability in a subset of NFPTs. [Conclusions] This study demonstrates that SST3-agonists activate signaling mechanisms that reduce NFPT cell viability and inhibit pituitary tumor growth in experimental models that expresses SST3, suggesting that targeting this receptor could be an efficacious treatment for NFPTs.This work has been funded by the following grants: Junta de Andalucía [CTS-1406 (R.M. Luque), BIO-0139 (J.P. Castaño)]; Ministerio de Ciencia, Innovación y Universidades [BFU2016-80360-R (J.P. Castaño)] and Instituto de Salud Carlos III, co-funded by European Union [ERDF/ESF, “Investing in your future”: PI16/00264 (R.M. Luque), CP15/00156 (M.D. Gahete) and CIBERobn]. CIBER is an initiative of Instituto de Salud Carlos III

Function and Structure of the RWD Domain

Fil: Paez Pereda, Marcelo. Max Plack Institute of Psychiatry; AlemaniaFil: Arzt, Eduardo Simon. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación en Biomedicina de Buenos Aires; Argentin

Nerve growth factor abrogates the tumorigenicity of human small cell lung cancer cell lines

Nerve growth factor (NGF) has antiproliferative and differentiating effects on adenomas of neuroendocrine origin. Cell lines derived from small-cell lung carcinoma (SCLC), a very aggressive neuroendocrine tumor, express NGF receptors. The role of NGF in the control of proliferation and progression of this carcinoma, however, has never been investigated. Chronic exposure of NCI-N-592 and GLC8 SCLC cell lines to NGF remarkably inhibited their proliferation rate both in vitro and in vivo, prevented their anchorage-independent clonal growth in soft agar, impaired their invasive capacity in vitro, and abolished their tumorigenic potential in nude mice. The proliferative response of SCLC cell lines to nicotine was also remarkably impaired by in vitro NGF treatment. Furthermore, NGF treatment activates in SCLC cell lines the expression and secretion of NGF. NGF thus reverts SCLC cell lines to a noninvasive, nontumorigenic phenotype that does not respond to nicotine and produces NGF

Octreotide, a somatostatin analogue, mediates its antiproliferative action in pituitary tumor cells by altering phosphatidylinositol 3-kinase signaling and inducing Zac1 expression.

Somatostatin limits cell growth by inhibiting the proliferative activity of growth factor receptors. In this study, it is shown that in pituitary tumor cells, the somatostatin analogue octreotide produces its antiproliferative action by inducing the expression the tumor suppressor gene Zac1. ZAC/Zac1 induces cell cycle arrest and apoptosis and is highly expressed in normal pituitary, mammary, and ovarian glands but is down-regulated in pituitary, breast, and ovarian tumors. Knocking down Zac1 by RNA interference abolished the antiproliferative effect of octreotide in pituitary tumor cells, indicating that Zac1 is necessary for the action of octreotide. The effect of octreotide on Zac1 expression was pertussis toxin sensitive and was abolished after transfection with a dominant negative vector for SHP-1. Zac1 is a target of the phosphatidylinositol 3-kinase (PI3K) survival pathway. Octreotide treatment decreased the tyrosine phosphorylation levels of the PI3K regulatory subunit p85, induced dephosphorylation of phosphoinositide-dependent kinase 1 (PDK1) and Akt, and activated glycogen synthase kinase 3beta (GSKbeta). Therefore, in pituitary tumor cells, somatostatin analogues produce their antiproliferative action by acting on the PI3K/Akt signaling pathway and increasing Zac1 gene expression.Journal ArticleResearch Support, Non-U.S. Gov'tinfo:eu-repo/semantics/publishe