http://repub.eur.nl/res/aut/7584/ List of Publications en http://repub.eur.nl/static-eur/img/logo.png http://repub.eur.nl http://repub.eur.nl/res/pub/25255/ 2009-03-01T00:00:00Z We recently demonstrated that interferon (IFN)-β has a more potent antitumor activity than IFN-α in BON cells, a neuroendocrine tumor (NET) cell line. The present study showed the role of type I IFNs in the modulation of the insulin-like growth factor (IGF) system in NETs. BON cells expressed IGF-I, IGF-II, IGF-I receptor, and insulin receptor mRNA. In addition, IGF-I and IGF-II stimulated the proliferation of BON cells and induced an inhibition of DNA fragmentation (apoptosis). As evaluated by quantitative RT-PCR, treatment with IFN-α (100 IU/ml) or IFN-β (100 IU/ml) inhibited the expression of IGF-II mRNA (-42% and -65%, respectively, both P < 0.001), whereas IGF-I receptor mRNA was significantly upregulated by IFN-α (+28%, P < 0.001) and downregulated by IFN-β (-47%, P < 0.001). Immunoreactive IGF-II concentration decreased in the conditioned medium during IFN-α (-16%, P < 0.05) and IFN-β (-69%, P < 0.001) treatment. Additionally, IGF-I receptor bioactivity was reduced (-54%) after IFN-β treatment. Scatchard analysis of125I-labeled IGF-I binding to cell membrane of BON cells revealed a dramatic suppression of maximum binding capacity only in the presence of IFN-β. Finally, the proapoptotic activity of IFN-β was partially counteracted by the coadministration of IGF-I and IGF-II (both at 50 nM). In conclusion, these data demonstrate that the IGF system has an important role in autocrine/paracrine growth of BON cells. The more potent antitumor activity of IFN-β compared with IFN-α could be explained by several effects on this system: 1) both IFNs inhibit the transcription of IGF-II, but the suppression is significantly higher after IFN-β than IFN-α and 2) only IFN-β inhibits the expression of IGF-I receptor. Copyright http://repub.eur.nl/res/pub/25470/ 2009-01-01T00:00:00Z Background: The role of dopamine agonists in the treatment of Cushing's disease (CD) has been previously debated. Aim: The aim of this study was to evaluate the effectiveness of short-term (3 months) and long-term (12-24 months) treatment with cabergoline in patients with CD. Patients and Methods: 20 patients with CD unsuccessfully treated by surgery entered the study. Cabergoline was administered at an initial dose of 1 mg/wk, with a monthly increase of 1 mg, until urinary cortisol levels normalized or the maximal dose of 7 mg/wk was achieved. There sponsiveness to treatment was evaluated according to changes in urinary cortisol excretion. A decrease greater than 25% was considered as a partial response, whereas complete normalization was considered as a full response at short-term evaluation; persistence of normal cortisol excretion was the only criterion to evaluate the response at long-term evaluation. Results: After short-term treatment, 15 (75%) patients were responsive to cabergoline treatment. Among these, normalization of cortisol excretion was maintained in 10, whereas treatment escape was observed in five patients after 6-18 months. Among the 10 long-term responsive patients, eight were followed for 24 months, whereas the remaining two were followed for 12-18 months, due to cabergoline withdrawal for intolerance. A sustained control of cortisol secretion for 24 month cabergoline treatment at the maximal dose ranging from 1-7 mg/wk (median: 3.5) without significant side effects, was obtained in eight of 20 (40%) patients. Conclusions: The results of this study demonstrated that cabergoline treatment is effective in controlling cortisol secretion for at least 1-2 yr in more than one third of a limited population of patients with CD. If this evidence is confirmed by additional studies, this agent may be considered as a useful treatment option in patients with CD who are unsuccessfully treated by neurosurgery. Copyright http://repub.eur.nl/res/pub/35292/ 2007-08-01T00:00:00Z OBJECTIVE: We evaluated the role of type I interferons (IFNs) and IFN receptors in the regulation of cell growth in 3 human pancreatic adenocarcinoma cell lines (BxPC-3, MiaPaCa-2, and Panc-1). BACKGROUND: Chemotherapy and radiotherapy have a marginal role in the management of pancreatic adenocarcinoma. The addition of IFN-α showed promising results in early clinical trials. METHODS: Cell proliferation and apoptosis were evaluated by DNA measurement and DNA fragmentation, respectively. Type I IFN receptor (IFNAR-1 and IFNAR-2 subunits) was determined by quantitative RT-PCR and immunocytochemistry. Cell cycle distribution was evaluated by propidium iodide staining and flow-cytometric analysis. RESULTS: The incubation with IFN-β for 6 days showed a potent inhibitory effect on the proliferation of BxPC-3 (IC50, 14 IU/mL) and MiaPaCa-2 (IC50, 64 IU/mL). The inhibitory effect of IFN-β was stronger than IFN-α in all 3 cell lines and mainly modulated by the stimulation of apoptosis, although cell cycle arrest was induced as well. The expression of the type I IFN receptors was significantly higher in BxPC-3 (the most sensitive cell line to IFN) and mainly localized on the membrane, whereas in Panc-1 (the most resistant cell line) about 60% to 70% of cells were negative for IFNAR-2c with a mainly cytoplasmic staining for IFNAR-2c. CONCLUSION: The antitumor activity of IFN-β is more potent than IFN-α in pancreatic cancer cell lines through the induction of apoptosis. Further studies should investigate in vivo whether the intensity and distribution of IFNAR-1 and IFNAR-2c may predict the response to therapy with IFN-α and IFN-β in pancreatic cancer. http://repub.eur.nl/res/pub/36653/ 2007-05-01T00:00:00Z Purpose: We have previously shown that transgenic mice ubiquitously overexpressing the HMGA2 gene develop growth hormone/prolactin-secreting pituitary adenomas. This animal model has been used to evaluate the therapeutic efficacy of SOM230, a somatostatin analogue with high affinity for the somatostatin receptor subtypes 1, 2, 3, and 5, on the growth of the pituitary adenomas. Experimental Design: Four groups of 3- and 9-month-old HMGA2 transgenic mice were treated for 3 months with a continuous s.c. injection of two different dosages of SOM230 (5 or 50 μg/kg/h), one dose of octreotide, corresponding to that used in human therapy, and a placebo, respectively. The development of the tumor before and after therapy was monitored by magnetic resonance imaging of the pituitary region and evaluation of the serum prolactin levels. Results: The highest dose of SOM230 induced a drastic regression of the tumor, whereas octreotide was not able to induce any significant tumor regression, although tumor progression was significantly slowed down. No significant differences were observed between the animals treated with the lowest dose of SOM230 and those receiving placebo. Conclusions: These results clearly support the efficacy of the SOM230 treatment in human pituitary adenomas secreting prolactin based on the dramatic tumor shrinkage and fall in prolactin levels. This beneficial effect could be of crucial clinical usefulness in patients bearing tumors resistant to dopaminergic drugs. http://repub.eur.nl/res/pub/36297/ 2007-04-01T00:00:00Z The dopaminergic system has a pivotal role in the central nervous system but also plays important roles in the periphery, mainly in the endocrine system. Dopamine exerts its functions via five different receptors, named D1-D5, belonging to the category of G protein coupled membrane receptors. Dopamine receptors are heterogeneously expressed in different cells, tissues and organs, where they stimulate or inhibit different functions, including neurotransmission and hormone synthesis and secretion. In particular, the dopamineric system has a pivotal role in the physiological regulation of the hypothalamus-pituitary-adrenal axis. Recent data have demonstrated the expression and function of dopamine receptors not only in endocrine organs but also in endocrine tumors, mainly those belonging to the hypothalamus-pituitary-adrenal axis, and also in the so-called 'neuroendocrine' tumors. These data confirm the important role of the dopaminergic system in this endocrine axis, as well as in the neuroendocrine system. This review summarizes the main structural and functional characteristics of dopamine receptors, emphasizing the most recent novelties, and focused on the physiological and pathological regulation of the hypothalamus-pituitary-adrenal axis by the dopaminergic system. In addition, the recent findings on the relationship between dopamine receptors and neuroendocrine tumors are summarized. http://repub.eur.nl/res/pub/14101/ 2007-01-01T00:00:00Z BACKGROUND: Dopamine receptor (DR) expression and dopamine agonist (DA) effectiveness have never been demonstrated in neuroendocrine tumors associated with ectopic ACTH syndrome (EAS). AIM: The aim of the current study was to evaluate DR and particularly D2 subtype expression in neuroendocrine tumors associated with EAS and to evaluate the in vivo effectiveness of the DA cabergoline in the treatment of EAS. PATIENTS AND METHODS: Six ACTH-secreting neuroendocrine tumors, including four lung, one pancreatic, and one thymic carcinoid, were used for the evaluation of D2 expression by immunohistochemistry. DR subtypes and D2 isoforms and number were evaluated by RT-PCR in three cases of persistent EAS after surgery. These patients were treated with cabergoline at the dose of 3.5 mg/wk for 6 months. Clinical parameters, hormonal levels, and tumor size were monitored during the treatment period. Results: At immunohistochemistry, D2 was expressed in five (83.3%) tumors. At RT-PCR, D2 was confirmed in all three cases but at variable numbers, whereas D4 was expressed in two cases. D(2long) was expressed in all three cases, together with D(2short) in one case. A normalization of urinary cortisol levels was found in two patients (66.7%) after 3 months of treatment. However, treatment escape was demonstrated in one of these patients afterward. CONCLUSION: The results of this study demonstrated that DR are expressed in neuroendocrine tumors associated with EAS and that cabergoline treatment could be effective in controlling cortisol excess in a subgroup of patients with EAS. Further studies on a larger number of patients are mandatory to confirm the usefulness of DA in EAS. http://repub.eur.nl/res/pub/10340/ 2004-01-01T00:00:00Z The role of dopamine agonist treatment in corticotroph pituitary tumors is controversial. The aim of this study was to evaluate D(2) receptor expression in 20 corticotroph pituitary tumors and to correlate it to the in vitro effect of dopamine agonists on ACTH secretion and the in vivo effect of short-term cabergoline treatment on cortisol secretion. D(2) expression was evaluated by receptor-ligand binding, immunohistochemistry, and RT-PCR. A 50% or more decrease in daily urinary cortisol levels was considered a significant clinical response. At receptor-ligand binding, specific binding of [(125)I]epidepride was found in 80% of cases. At immunohistochemistry, specific D(2) immunostaining was found in 75% of cases. D(2) expression was found in 83.3% of cases (D(2long) in 40%, D(2short) in 20%, and both in 40%) by RT-PCR. Significant in vitro inhibition of ACTH secretion was found in 100% of D(2)-positive cases, but not in 100% of D(2)-negative cases by either bromocriptine or cabergoline. A significant in vivo inhibition of cortisol secretion after 3-month cabergoline treatment was found in 60%, although a normalization of cortisol secretion was found in 40% of cases. All cabergoline-responsive cases were associated with D(2) expression, whereas all noncabergoline-responsive cases but one were not associated with D(2) expression. In conclusion, functional D(2) receptors were expressed in approximately 80% of corticotroph pituitary tumors. The effectiveness of cabergoline in normalizing cortisol secretion in 40% of cases supports its therapeutic use in the management of Cushing's disease. http://repub.eur.nl/res/pub/9466/ 2000-01-01T00:00:00Z The thymus exhibits a pattern of aging oriented toward a physiological involution. The structural changes start with a steady decrease of thymocytes, whereas no major variations occur in the number of thymic epithelial cells (TEC). The data concerning the role of hormones and neuropeptides in thymic involution are equivocal. We recently demonstrated the presence of somatostatin (SS) and three different SS receptor (SSR) subtypes in the human thymus. TEC selectively expressed SSR subtype 1 (sst(1)) and sst(2A). In the present study we investigated whether SSR number is age related in the thymus. Binding of the sst(2)-preferring ligand (125)I-Tyr(3)-octreotide was evaluated in a large series of normal human thymuses of different age by SSR autoradiography and ligand binding on tissue homogenates. The score at autoradiography and the number of SSR at membrane homogenate binding (B(max)) were inversely correlated with the thymus age (r = -0.84, P < 0.001; r = -0.82, P < 0.001, respectively). The autoradiographic score was positively correlated with the B(max) values (r = 0.74, P < 0.001). Because the TEC number in the age range considered remains unchanged, the decrease of octreotide binding sites might be due to a reduction of sst(2A) receptor number on TEC. The age-related expression of a receptor involved mainly in controlling secretive processes is in line with the evidence that the major changes occurring in TEC with aging are related to their capabilities in producing thymic hormones. In conclusion, SS and SSR might play a role in the involution of the human thymus. These findings underline the links between the neuroendocrine and immune systems and support the concept that neuropeptides participate in development of cellular immunity in humans. http://repub.eur.nl/res/pub/8996/ 1999-01-01T00:00:00Z Somatostatin (SS) and its analogs exert inhibitory effects on secretive and proliferative processes of various cells via high affinity SS receptors (SS-R). SS analogs bind with different affinity to the five cloned SS-R subtypes. Octreotide, an octapeptide SS analog, binds with high affinity to the SS-R subtype 2 (sst2). SS-R have been demonstrated in vivo and in vitro on cells from endocrine and immune systems. Among the lymphatic tissues, the thymus has been shown to contain the highest amount of SS, suggesting a local functional role of the peptide. We investigated the SS distribution and SS-R expression pattern in the normal human thymus using autoradiography, membrane homogenate binding studies, and RT-PCR. In addition, the effect of SS and octreotide on growth of cultured thymic epithelial cells (TEC) was studied. By autoradiography, binding of [125I-Tyr0]-SS-28 and [125I-Tyr3]-octreotide was detected in all seven thymuses studied. Specific [125I-Tyr3]-octreotide binding was shown on membrane preparations from thymuses, while not from cultured thymocytes. RT-PCR showed the expression of sst1, sst2A and sst3 messenger RNA (mRNA) in the thymic tissue, whereas sst1 and sst2A mRNAs were found in isolated TEC. SS mRNA was present in thymic tissue and in isolated TEC. SS and octreotide significantly inhibited 3H-thymidine incorporation in 3 of 3 and 6 of 6 TEC cultures, respectively. The percent inhibition ranged from 38.8 to 66.8% for SS and from 19.1 to 59.5% for octreotide. In conclusion, SS mRNA and sst1, sst2A, and sst3 mRNAs are expressed in the normal human thymus. Cultured TEC selectively express sst1 and sst2A mRNA and respond in vitro to SS and octreotide administration with an inhibition of cell proliferation. These data suggest a paracrine/autocrine role of SS and its receptors in the regulation of cell growth in thymic microenvironment.