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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; Alemania Fil: 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; Argentina Fil: Paez Pereda, Marcelo. Max Planck Institut Fur Psychiatrie; Alemania Fil: Theodoropoulou, Marily. Technische Universitat München; Alemania Fil: Ciato, Denis. Technische Universitat München; Alemania Fil: Renner, Ulrich. Max Planck Institut Fur Psychiatrie; Alemania

Glucocorticoid receptor (GR) activity is modulated by posttranslational modifications, including phosphorylation, ubiquitination, and SUMOylation. The GR has three SUMOylation sites: lysine 297 (K297) and K313 in the N-terminal domain (NTD) and K721 within the ligand-binding domain. SUMOylation of the NTD sites mediates the negative effect of the synergy control motifs of GR on promoters with closely spaced GR binding sites. There is scarce evidence on the role of SUMO conjugation to K721 and its impact on GR transcriptional activity. We have previously shown that RSUME (RWD-containing SUMOylation enhancer) increases protein SUMOylation.We nowdemonstrate that RSUME interacts with the GR and increases its SUMOylation. RSUME regulatesGRtranscriptional activity and the expression of its endogenous target genes, FKBP51 and S100P. RSUME uncovers a positive role for the third SUMOylation site, K721, on GR-mediated transcription, demonstrating thatGRSUMOylation acts positively in the presence of a SUMOylation enhancer. Both mutation of K721 and small interfering RNA-mediated RSUME knockdown diminish GRIP1 coactivator activity. RSUME, whose expression is induced under stress conditions, is a key factor in heat shock-inducedGRSUMOylation. These results show that inhibitory and stimulatorySUMOsites are present in theGRand at higher SUMOylation levels the stimulatory one becomes dominant. Fil: Druker, Jimena Paola. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación en Biomedicina de Buenos Aires; Argentina Fil: Liberman, Ana Clara. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación en Biomedicina de Buenos Aires; Argentina Fil: Antunica Noguerol, María de Las Nieves. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación en Biomedicina de Buenos Aires; Argentina Fil: Gerez, Juan Atilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación en Biomedicina de Buenos Aires; Argentina Fil: Paez Pereda, Marcelo. Max Planck Institute of Psychiatry; Alemania Fil: Rein, Theo. Max Planck Institute of Psychiatry; Alemania Fil: Iñiguez Lluhi, Jorge A.. University of Michigan Medical School. Department of Pharmacology; Estados Unidos Fil: Holsboer, Florian. Max Planck Institute of Psychiatry; Alemania 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; Argentina

RSUME (RWD-containing SUMO Enhancer) is a small protein that increases SUMO conjugation to proteins. To date, four splice variants that codify three RSUME isoforms have been described, which differ in their C-terminal end. Comparing the structure of the RSUME isoforms we found that, in addition to the previously described RWD domain in the N-terminal, all these RSUME variants also contain an intermediate domain. Only the longest RSUME isoform presents a C-terminal domain that is absent in the others. Given these differences, we used the shortest and longest RSUME variants for comparative studies. We found that the C-terminal domain is dispensable for the SUMO-conjugation enhancer properties of RSUME. We also demonstrate that these two RSUME variants are equally induced by hypoxia. The NF-kB signaling pathway is inhibited, and the HIF-1 expression and HIF-1 activity are increased more efficiently by the longest RSUME. In addition, the mRNA levels of these isoforms differ in human glioma samples; while the shortest RSUME isoform is expressed in all the tumors analyzed, the longest variant is expressed in most but not all of them. The results presented here show a degree of redundancy of the RSUME variants on the SUMO pathway. However, the increased inhibition conferred by RSUME267 over the NF-kB signaling pathway, the increased activation over the HIF-1 pathway and the different expression of the RSUME isoforms suggest specific roles for each RSUME isoform which may be relevant in certain types of brain tumors that express RSUME, like human pituitary adenomas and gliomas. Fil: Gerez, Juan Atilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque. Centenario. Instituto de Investigación en Biomedicina de Buenos Aores - CONICET -Instituto Partner Sociedad Max Planck; Argentina; Fil: Fuertes, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque. Centenario. Instituto de Investigación en Biomedicina de Buenos Aores - CONICET -Instituto Partner Sociedad Max Planck; Argentina; Fil: Tedesco, Lucas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque. Centenario. Instituto de Investigación en Biomedicina de Buenos Aores - CONICET -Instituto Partner Sociedad Max Planck; Argentina; Fil: Silberstein Cuña, Susana Iris. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque. Centenario. Instituto de Investigación en Biomedicina de Buenos Aores - CONICET -Instituto Partner Sociedad Max Planck; Argentina; Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Fisiologia, Biologia Molecular y Celular. Laboratorio de Fisiologia y Biologia Molecular; Argentina; Fil: Sevlever, Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque. Centenario. Instituto de Investigación en Biomedicina de Buenos Aores - CONICET -Instituto Partner Sociedad Max Planck; Argentina; Fil: Paez-Pereda, Marcelo. Max Planck Institute of Psychiatry; Alemania; Fil: Holsboer, Florian. Max Planck Institute of Psychiatry; Alemania; Fil: Turjanski, Adrian. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias; Argentina; Fil: Arzt, Eduardo Simon. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque. Centenario. Instituto de Investigación en Biomedicina de Buenos Aores - CONICET -Instituto P; Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Fisiologia, Biologia Molecular y Celular. Laboratorio de Fisiologia y Biologia Molecular; Argentina

Rapamycin and its analogues have significant antiproliferative action against a variety of tumors. However, sensitivity to rapamycin is reduced by Akt activation that results from the ablative effects of rapamycin on a p70 S6K–induced negative feedback loop that blunts phosphoinositide 3-kinase (PI3K)–mediated support for Akt activity. Thus, sensitivity to rapamycin might be increased by imposing an upstream blockade to the PI3K/Akt pathway. Here, we investigated this model using the somatostatin analogue octreotide as a tool to decrease levels of activated Ser473-phosphorylated Akt (pAkt-Ser473) in pituitary tumor cells that express somatostatin receptors. Octreotide increased levels of phosphorylated insulin receptor substrate-1 that were suppressed by rapamycin, subsequently decreasing levels of pAkt-Ser473 through effects on phosphotyrosine phosphatase SHP-1. Octreotide potentiated the antiproliferative effects of rapamycin in immortalized pituitary tumor cells or human nonfunctioning pituitary adenoma cells in primary cell culture, sensitizing tumor cells even to low rapamycin concentrations. Combined treatment of octreotide and rapamycin triggered G1 cell cycle arrest, decreasing E2F transcriptional activity and cyclin E levels by increasing levels of p27/Kip1. These findings show that adjuvant treatment with a somatostatin analogue can sensitize pituitary tumor cells to the antiproliferative effects of rapamycin. Cancer Res; 70(2); 666–74

Context: Sonic hedgehog (Shh) belongs to a family of signaling proteins involved in development and has been recently implicated in cancer. Shh signaling is active in the corticotrophs of the adult pituitary gland, where it cross-talks with the CRH pathway and regulates ACTH secretion. Because developmental pathways are involved in pituitary tumorigenesis, we hypothesized that Shh may be important in pituitary tumors. Objective: The objective of this study was to examine the expression and function of Shh-pathway components in pituitary adenomas. Methods: Using immunohistochemistry, we determined the expression of Shh and its receptors Patched 1 (Ptc1) and Patched 2 (Ptc2) in 55 human pituitary adenomas compared with the normal pituitary gland. The AtT-20 and GH3 pituitary tumor cell lines were used as models for studying the role of Shh on cell proliferation and hormone secretion. The effect of Shh on hormone secretion was confirmed in primary cultures of normal rat pituitaries and human pituitary tumors. Results: Ptc1 and Ptc2 were present, whereas Shh was down-regulated in pituitary adenomas and completely absent in Cushing tumors. Shh inhibited cell proliferation in AtT-20 corticotrophinoma cells and the Shh-specific inhibitor cyclopamine increased proliferation in GH3 mammosomatotrophinoma cells. On the other hand, exogenous administration of Shh increased hormone secretion from normal rat pituitaries, pituitary cell lines, and 10 different pituitary tumors. Conclusions: Our results suggest that Shh might maintain pituitary cells in a nonproliferative state. We conclude that Shh is a newly described hypophysiotropic cytokine and its down-regulation may be involved in the pathogenesis of pituitary adenomas. Copyright © 2005 by The Endocrine Society.