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Raverot G, Jouanneau E, Trouillas J. Management of endocrine disease: clinicopathological classification and molecular markers of pituitary tumours for personalized therapeutic strategies. Eur J Endocrinol 2014; 170:R121-32. [PMID: 24431196 DOI: 10.1530/eje-13-1031] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Pituitary tumours, the most frequent intracranial tumour, are historically considered benign. However, various pieces of clinical evidence and recent advances in pathological and molecular analyses suggest the need to consider these tumours as more than an endocrinological disease, despite the low incidence of metastasis. Recently, we proposed a new prognostic clinicopathological classification of these pituitary tumours, according to the tumour size (micro, macro and giant), type (prolactin, GH, FSH/LH, ACTH and TSH) and grade (grade 1a, non-invasive; 1b, non-invasive and proliferative; 2a, invasive; 2b, invasive and proliferative and 3, metastatic). In addition to this classification, numerous molecular prognostic markers have been identified, allowing a better characterisation of tumour behaviour and prognosis. Moreover, clinical and preclinical studies have demonstrated that pituitary tumours could be treated by some chemotherapeutic drugs or new targeted therapies. Our improved classification of these tumours should now allow the identification of prognosis markers and help the clinician to propose personalised therapies to selected patients presenting tumours with a high risk of recurrence.
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Affiliation(s)
- Gerald Raverot
- INSERM U1028, CNRS UMR5292, Lyon Neuroscience Research Center, Neuro-Oncology and Neuro-Inflammation Team, Lyon F-69372, France
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Abstract
Apoptosis, also known as programmed cell death, is a phenomenon in which different stimuli trigger cellular mechanisms that culminate in death, in the absence of inflammatory cell response. Two different activation pathways are known, the intrinsic pathway (or mitochondrial) and extrinsic (or death-receptor pathway), both pathways trigger enzymatic reactions that lead cells to break up and be phagocytized by neighboring cells. This process is a common occurrence in physiological and pathological states, participating in the control of cell proliferation, differentiation and remodeling of organs. In the early steps of pituitary gland formation, numerous apoptotic cells are detected in the separation of Rathke's pouch from the roof of oral ectoderm. In the distal part of the gland, which will form the adenohypophysis, the ratio of apoptosis was significantly lower. However, there is evidence that neoplastic pituitary cells undergo unbalance in genes that control apoptosis leading to uncontrolled cell growth. No direct evidence of apoptosis was found in the drugs used for tumors producing prolactin and growth hormone. In conclusion, an unbalancing in the apoptosis process is the boundary between development and tumor growth.
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Affiliation(s)
- M F Guzzo
- Neuroendocrine Unit, Division of Endocrinology and Metabolism, Hospital das Clínicas, University of Sao Paulo Medical School, São Paulo, Brazil
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53
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Management of aggressive pituitary adenomas and pituitary carcinomas. J Neurooncol 2014; 117:459-68. [DOI: 10.1007/s11060-014-1413-6] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Accepted: 02/21/2014] [Indexed: 10/25/2022]
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Cámara Gómez R. Tumores hipofisarios no funcionantes: actualización 2012. ACTA ACUST UNITED AC 2014; 61:160-70. [DOI: 10.1016/j.endonu.2013.04.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2012] [Revised: 03/27/2013] [Accepted: 04/02/2013] [Indexed: 01/10/2023]
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Theodoropoulou M, Stalla GK. Somatostatin receptors: from signaling to clinical practice. Front Neuroendocrinol 2013; 34:228-52. [PMID: 23872332 DOI: 10.1016/j.yfrne.2013.07.005] [Citation(s) in RCA: 241] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 06/13/2013] [Accepted: 07/12/2013] [Indexed: 02/08/2023]
Abstract
Somatostatin is a peptide with a potent and broad antisecretory action, which makes it an invaluable drug target for the pharmacological management of pituitary adenomas and neuroendocrine tumors. Somatostatin receptors (SSTR1, 2A and B, 3, 4 and 5) belong to the G protein coupled receptor family and have a wide expression pattern in both normal tissues and solid tumors. Investigating the function of each SSTR in several tumor types has provided a wealth of information about the common but also distinct signaling cascades that suppress tumor cell proliferation, survival and angiogenesis. This provided the rationale for developing multireceptor-targeted somatostatin analogs and combination therapies with signaling-targeted agents such as inhibitors of the mammalian (or mechanistic) target of rapamycin (mTOR). The ability of SSTR to internalize and the development of rabiolabeled somatostatin analogs have improved the diagnosis and treatment of neuroendocrine tumors.
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Affiliation(s)
- Marily Theodoropoulou
- Department of Endocrinology, Max Planck Institute of Psychiatry, Kraepelinstrasse 10, 80804 Munich, Germany.
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Jallad RS, Bronstein MD. The place of medical treatment of acromegaly: current status and perspectives. Expert Opin Pharmacother 2013; 14:1001-15. [PMID: 23600991 DOI: 10.1517/14656566.2013.784744] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
INTRODUCTION Acromegaly is characterized by elevated growth hormone (GH) and insulin-like growth factor-I (IGF-I) levels and by progressive somatic disfigurement and systemic manifestations, which lead to a mortality rate higher than the general population. Therefore, diagnosis and properly treatment should be performed as soon as possible. AREAS COVERED This article focuses on the state of the art of acromegaly medical treatment. Somatostatin analogs, dopamine agonists and GH receptor antagonist were reviewed. Somatostatin analogs, the first-choice pharmacotherapy, can be used as primary or pre-operative treatment or as secondary therapy after failed surgery. Dopamine agonists have been used in patients with slightly elevated hormone levels and/or mixed GH/prolactin adenomas. Pegvisomant is indicated for resistant to somatostatin analogs/dopamine agonists. Combined treatment is also an option for resistant cases. Other non-conventional therapies and perspectives of treatment were also been discussed. EXPERT OPINION The control of disease activity in acromegaly is of paramount importance. Medical treatment is an important option for cases in which surgery was unsuccessful or not indicated. Despite the achievements in medical treatment, somatotropic tumor aggressiveness and/or resistance to the drugs currently available remain a concern. Therefore, novel therapy targets based on molecular pathogenesis of GH-secreting tumors are currently in development, aiming at fulfilling this important gap.
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Affiliation(s)
- Raquel S Jallad
- University of Sao Paulo Medical School, Hospital das Clinicas, Division of Endocrinology and Metabolism, Neuroendocrine Unit, São Paulo, Brasil
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Sajjad EA, Zieliński G, Maksymowicz M, Hutnik Ł, Bednarczuk T, Włodarski P. mTOR is frequently active in GH-secreting pituitary adenomas without influencing their morphopathological features. Endocr Pathol 2013; 24:11-9. [PMID: 23296986 DOI: 10.1007/s12022-012-9230-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Initiating factors and mechanisms of tumor formation are poorly understood in nonfamilial pituitary adenomas. Alteration of intracellular pathways is an underlying event in numerous neoplasms. Among them, excessive activation of mammalian target of rapamycin (mTOR) pathway and its two main regulators, Akt and Erk, has been detected frequently in solid tumors. This study tests the activation of mTOR pathway in pituitary adenomas and its influence on their morphopathological features. Fifty-three pituitary adenomas were fresh frozen after surgery and analyzed by western blotting using phospho-specific antibodies. The impact of Akt and Erk activation on mTOR pathway was assessed in five primary cultures derived from the excised adenomas using selective kinase inhibitors. Statistical correlations of size, volume, Ki-67 %, Knosp's grading, and somatostatin receptor (SSTR) expression with the activation of mentioned kinases was performed. GHomas showed the highest frequency (71 %) and level of mTOR pathway activity comparing to other adenomas (33 %). No significant correlation was found between mTOR activation and any of the morphopathological features in the studied samples. mTOR kinase phosphorylation was independent of Erk and Akt in primary cultures. Erk activity was significant in all types of adenomas but was the highest in control samples. Its phosphorylation correlated inversely with the Knosp's grading in nonfunctional pituitary adenomas and directly with somatostatin receptor subtype 2 A expression in GHomas. Presented data point to the noteworthy mTOR activity in GHomas. However, the lack of correlation with morphopathological features, its independence of Erk and Akt phosphorylation, and high level of Erk activity in control pituitary necessitate further research for clarifying the role of these pathways in pituitary adenomas.
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Affiliation(s)
- Emir Ahmed Sajjad
- Department of Histology and Embryology, Center for Biostructure Research, Medical University of Warsaw, Chałubińskiego 5, 02-004, Warszawa, Poland
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58
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Tulipano G, Faggi L, Losa M, Mortini P, Spinello M, Sibilia V, Pagani F, Cocchi D, Giustina A. Effects of AMPK activation and combined treatment with AMPK activators and somatostatin on hormone secretion and cell growth in cultured GH-secreting pituitary tumor cells. Mol Cell Endocrinol 2013; 365:197-206. [PMID: 23116772 DOI: 10.1016/j.mce.2012.10.017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2012] [Revised: 10/18/2012] [Accepted: 10/18/2012] [Indexed: 12/25/2022]
Abstract
We investigated the effects of the AMPK activator AICAR as compared to somatostatin-14 on cell viability and GH secretion in human GH-secreting pituitary adenomas in vitro and in rat GH3 cells. Overnight treatment with AICAR increased phospho-(threonine-172) AMPK levels (activated AMPK) in cultured human adenomas. As to the effects on cell viability, four adenomas out of 15 were responsive to AICAR (0.4mM) and five adenomas were responsive to SS-14 (100 nM). One adenoma was responsive to both somatostatin and AICAR. The effects of cotreatment with SS-14 and AICAR were investigated in eight adenomas. In two adenomas, the effects of AICAR+SS-14 did not exceed the effect of AICAR. In two adenomas which were not responsive to either AICAR or SS-14, the cotreatment was able to reduce cell viability versus control. Two adenomas were not responsive to any treatment. As to the effects on GH secretion, nine adenomas out of 15 were responsive to AICAR. Twelve adenomas were responsive to SS-14. Eight adenomas were responsive to both AICAR and SS-14. Cotreatment exceeded the effect of single treatments in 4 out of 10 adenomas. In GH3 cells, AICAR reduced the activity of p70S6 kinase, which plays an important role in cell growth. SS-14 did not affect significantly AMPK phosphorylation and p70S6K activity but it was able to enhance the inhibitory effect of AICAR on phospho-S6 levels. Moreover, AICAR and SS-14 reduced ERK phosphorylation with a different time course. The combined treatment reduced phospho-ERK levels at any time point.
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Affiliation(s)
- Giovanni Tulipano
- Pharmacology Unit, Department of Biomedical Sciences and Biotechnologies, University of Brescia, Italy.
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59
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Rubinfeld H, Shimon I. PI3K/Akt/mTOR and Raf/MEK/ERK signaling pathways perturbations in non-functioning pituitary adenomas. Endocrine 2012; 42:285-91. [PMID: 22552912 DOI: 10.1007/s12020-012-9682-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Accepted: 04/17/2012] [Indexed: 12/14/2022]
Abstract
Non-functioning pituitary adenomas (NFPAs) comprise a heterogeneous group, which are considered the most common pituitary tumor. As no clinically hormone hypersecretion is apparent, non-functioning pituitary adenomas are often diagnosed only when they are large enough to cause tumor mass effects, such as hypopituitarism, visual field defects or headaches. Efficient medical therapy for NFPAs is currently unavailable and surgical treatment of these tumors is not always satisfactory. Characterization of signaling regulatory events in the context of NFPAs may enable the development of new attractive novel strategies. Although data regarding gene expression profiling of signaling pathways in NFPAs have accumulated, studies aimed at fine-classification of NFPAs-specific signaling regulatory mechanisms and feedback loops are scarce.
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Affiliation(s)
- Hadara Rubinfeld
- Institute of Endocrinology and Metabolism and Felsenstein Medical Research Center, Rabin Medical Center, Beilinson Campus and Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel
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60
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Abstract
Multiple endocrine neoplasias (MEN) are a group of hereditary disorders characterized by tumors arising in more than one neuroendocrine tissue. There are two major forms which can occur in humans, MEN type 1 (MEN1) and MEN type 2 (MEN2). These syndromes are transmitted as autosomal dominant traits with high penetrance and have a different tumor spectrum. MEN1 and MEN2 are caused by germline mutations in the MEN1 and RET genes, respectively. Recently, a variant of the MEN syndromes was discovered in a rat colony and was named MENX since affected animals develop tumors with a spectrum that shares features with both MEN1 and MEN2 human syndromes. Extensive genetic studies identified a germline mutation in the Cdkn1b gene, encoding the p27 cell cycle inhibitor, as the causative mutation for MENX. Capitalizing on these findings, heterozygous germline mutations in the human homologue, CDKN1B, were searched for and identified in patients with multiple endocrine tumors. As a consequence of this discovery, a novel human MEN syndrome, named MEN4, was recognized which is caused by mutations in p27. Altogether these studies identified Cdkn1b/CDKN1B as a novel tumor susceptibility gene for multiple endocrine tumors in both rats and humans. Here I review the phenotypic features and the genetics of the MENX rat syndrome. I briefly address the main functions of p27 and how they are affected by the MENX-associated mutation. Finally, I present examples of how this animal model might be exploited as a translational platform for preclinical studies of pituitary adenomas.
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Affiliation(s)
- Natalia S Pellegata
- Institute of Pathology, Helmholtz Zentrum München-German Research Center for Environmental Health, Neuherberg, Germany.
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61
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Jouanneau E, Wierinckx A, Ducray F, Favrel V, Borson-Chazot F, Honnorat J, Trouillas J, Raverot G. New targeted therapies in pituitary carcinoma resistant to temozolomide. Pituitary 2012; 15:37-43. [PMID: 21858654 DOI: 10.1007/s11102-011-0341-0] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
To evaluate the antitumoral efficacy of everolimus in pituitary carcinoma resistant to temozolomide, the correlation with mammalian target of rapamycin (mTOR) signaling in the tumor and to present recent advances and future treatments of pituitary carcinomas. Pituitary carcinomas are rare and largely unresponsive to current treatment options. Recent reports on the antitumoral efficacy of temozolomide in some such patients are encouraging, yet most patients appear to show resistance to its actions. As a potential alternative, the mTOR inhibitor, everolimus, has been shown to potently inhibit pituitary cell proliferation highlighting mTOR inhibition as a promising therapeutic approach for pituitary carcinomas. We described the tumoral effects of a combination therapy with everolimus (5 mg/day) and octreotide (30 mg/month) and the mTOR signalling expression in a patient with pituitary ACTH carcinoma, compared to 17 other ACTH adenomas. Clinical and biochemical evaluation were performed every month, and imaging after 3 month of treatment. mTOR signaling was assessed by microarray expression analysis of each of the 18 adenoma tissues. Combined therapy failed to control pituitary tumor growth and ACTH secretion. Slight activation of mTOR signaling was found in all ACTH tumors alongside important variations between tumors. Low antitumor efficacy shown by everolimus might be explained by the weak activation of mTOR pathway in ACTH tumors. Everolimus treatment was inefficient at controlling secretion and tumor growth of one ACTH pituitary carcinoma. More clinical cases, with mTOR signalling expression analysis of the tumor, must be published before any conclusions can be drawn.
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Affiliation(s)
- Emmanuel Jouanneau
- INSERM, U1028/CNRS, UMR5292. Lyon Neuroscience Research Center, Neuro-Oncology and Neuro-inflammation Team, 69000, Lyon, France
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Lupp A, Nagel F, Doll C, Röcken C, Evert M, Mawrin C, Saeger W, Schulz S. Reassessment of sst3 somatostatin receptor expression in human normal and neoplastic tissues using the novel rabbit monoclonal antibody UMB-5. Neuroendocrinology 2012; 96:301-10. [PMID: 22414742 DOI: 10.1159/000337659] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2011] [Accepted: 02/28/2012] [Indexed: 11/19/2022]
Abstract
BACKGROUND Among the five somatostatin receptors (sst(1)-sst(5)), the sst(3) receptor displays a distinct pharmacological profile. Like sst(2), the sst(3) receptor efficiently internalizes radiolabeled somatostatin analogs. Unlike sst(2), however, internalized sst(3) receptors are rapidly transferred to lysosomes for degradation. Apart from this, very little is known about the clinical relevance of the sst(3) receptor, which may in part be due to the lack of specific monoclonal sst(3) antibodies. METHODS Here, we have extensively characterized the novel rabbit monoclonal anti-human sst(3) antibody UMB-5 using transfected cells and receptor-expressing tissues. UMB-5 was then subjected to immunohistochemical staining of a series of 190 formalin-fixed, paraffin-embedded normal and neoplastic human tissues. RESULTS Specificity of UMB-5 was demonstrated by detection of a broad band migrating at a molecular weight of 70,000-85,000 in immunoblots from human pituitary. After enzymatic deglycosylation, the size of this band decreased to a molecular weight of 45,000. Tissue immunostaining was completely abolished by pre-adsorption of UMB-5 with its immunizing peptide. In addition, UMB-5 detected distinct cell populations in human tissues like pancreatic islands, anterior pituitary, adrenal cortex, adrenal medulla, and enteric ganglia, similar to that seen with a rabbit polyclonal antibody generated against a different carboxyl-terminal epitope of the sst(3) receptor. In a comparative immunohistochemical study, UMB-5 yielded predominant plasma membrane staining in the majority of pituitary adenomas, pheochromocytomas, and a subset of neuroendocrine tumors. The sst(3) receptor was also present in many glioblastomas, pancreatic, breast, cervix, and ovarian carcinomas. CONCLUSION The rabbit monoclonal antibody UMB-5 may prove of great value in the identification of sst(3)-expressing tumors during routine histopathological examinations. Given its unique trafficking properties, these tumors may be potential candidates for sst(3)-directed receptor radiotherapy.
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Affiliation(s)
- Amelie Lupp
- Department of Pharmacology and Toxicology, University Hospital, Friedrich Schiller University Jena, Jena, Germany
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Abstract
CONTEXT Although pituitary tumors are common, pituitary carcinoma is very rare and is only diagnosed when pituitary tumor noncontiguous with the sellar region is demonstrated. Diagnosis is difficult, resulting in delays that may adversely effect outcome that is traditionally poor. Barriers to earlier diagnosis and management strategies for pituitary carcinoma are discussed. EVIDENCE ACQUISITION PubMed was employed to identify relevant studies, a review of the literature was conducted, and data were summarized and integrated from the author's perspective. EVIDENCE SYNTHESIS The available data highlight the difficulties in diagnosis and management and practical challenges in conducting clinical trials in this rare condition. They suggest that earlier diagnosis with aggressive multimodal therapy may be advantageous in some cases. CONCLUSIONS Although pituitary carcinoma remains difficult to diagnose and treat, recent developments have led to improved outcomes in selected cases. With broader use of molecular markers, efforts to modify current histopathological criteria for pituitary carcinoma diagnosis may now be possible. This would assist earlier diagnosis and, in combination with targeted therapies, potentially improve long-term survival.
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Affiliation(s)
- Anthony P Heaney
- Department of Medicine, David Geffen School of Medicine at University of California-Los Angeles, Los Angeles, California 90095, USA.
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64
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Lee M, Theodoropoulou M, Graw J, Roncaroli F, Zatelli MC, Pellegata NS. Levels of p27 sensitize to dual PI3K/mTOR inhibition. Mol Cancer Ther 2011; 10:1450-9. [PMID: 21646547 DOI: 10.1158/1535-7163.mct-11-0188] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Constitutive activation of the phosphatidylinositol 3-kinase (PI3K)/AKT/mTOR signaling cascade occurs in a variety of human malignancies, where it sustains tumor cell proliferation and survival. Pharmacologic blockade of this pathway exerts antineoplastic activity by triggering apoptosis and/or cell-cycle arrest. Pituitary adenomas show activation of the PI3K/AKT/mTOR pathway, but only a fraction of them respond in vitro to the antiproliferative action of rapamycin and RAD001 (mTOR inhibitors), possibly because of the described negative feedback loop on AKT which reactivates the signaling cascade. Rats affected by the multiple endocrine neoplasia-like syndrome (MENX) develop pituitary adenomas showing increased activated AKT. In this study, we comparatively investigated the antitumor potential of the novel dual PI3K/mTOR inhibitor NVP-BEZ235 and the single mTOR inhibitor RAD001 on rat pituitary adenoma cells in primary culture. NVP-BEZ235 inhibits the PI3K pathway both upstream and downstream of AKT, thereby preventing the negative feedback loop. NVP-BEZ235 was more effective than RAD001 in reducing cell viability of pituitary adenomas. Consistently, NVP-BEZ235 treatment decreased Akt and S6 phosphorylation and triggered apoptosis. Because MENX is caused by a germline loss-of-function mutation in the cell-cycle inhibitor p27Kip1, we investigated the relationship between this defect and response to NVP-BEZ235 treatment. The levels of p27Kip1 positively correlate with the response to NVP-BEZ235 treatment. Combined treatment with NVP-BEZ235 and the proteasome inhibitor bortezomib, which increases p27Kip1 amount, shows synergistic antiproliferative effects on pituitary adenoma cells. Our data suggest that NVP-BEZ235 may represent an effective therapeutic modality for pituitary adenomas and that p27Kip1 levels represent a potential predictor of response to dual PI3K/mTOR inhibition.
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Affiliation(s)
- Misu Lee
- Institute of Pathology, Helmholtz Zentrum München, Neuherberg, Germany
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65
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Radl DB, Ferraris J, Boti V, Seilicovich A, Sarkar DK, Pisera D. Dopamine-induced apoptosis of lactotropes is mediated by the short isoform of D2 receptor. PLoS One 2011; 6:e18097. [PMID: 21464994 PMCID: PMC3064585 DOI: 10.1371/journal.pone.0018097] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2010] [Accepted: 02/21/2011] [Indexed: 11/18/2022] Open
Abstract
Dopamine, through D2 receptor (D2R), is the major regulator of lactotrope function in the anterior pituitary gland. Both D2R isoforms, long (D2L) and short (D2S), are expressed in lactotropes. Although both isoforms can transduce dopamine signal, they differ in the mechanism that leads to cell response. The administration of D2R agonists, such as cabergoline, is the main pharmacological treatment for prolactinomas, but resistance to these drugs exists, which has been associated with alterations in D2R expression. We previously reported that dopamine and cabergoline induce apoptosis of lactotropes in primary culture in an estrogen-dependent manner. In this study we used an in vivo model to confirm the permissive action of estradiol in the apoptosis of anterior pituitary cells induced by D2R agonists. Administration of cabergoline to female rats induced apoptosis, measured by Annexin-V staining, in anterior pituitary gland from estradiol-treated rats but not from ovariectomized rats. To evaluate the participation of D2R isoforms in the apoptosis induced by dopamine we used lactotrope-derived PR1 cells stably transfected with expression vectors encoding D2L or D2S receptors. In the presence of estradiol, dopamine induced apoptosis, determined by ELISA and TUNEL assay, only in PR1-D2S cells. To study the role of p38 MAPK in apoptosis induced by D2R activation, anterior pituitary cells from primary culture or PR1-D2S were incubated with an inhibitor of the p38 MAPK pathway (SB203850). SB203580 blocked the apoptotic effect of D2R activation in lactotropes from primary cultures and PR1-D2S cells. Dopamine also induced p38 MAPK phosphorylation, determined by western blot, in PR1-D2S cells and estradiol enhanced this effect. These data suggest that, in the presence of estradiol, D2R agonists induce apoptosis of lactotropes by their interaction with D2S receptors and that p38 MAPK is involved in this process.
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Affiliation(s)
- Daniela Betiana Radl
- Facultad de Medicina, Instituto de Investigaciones en Reproducción, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Jimena Ferraris
- Facultad de Medicina, Instituto de Investigaciones en Reproducción, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Valeria Boti
- Facultad de Medicina, Instituto de Investigaciones en Reproducción, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Adriana Seilicovich
- Facultad de Medicina, Instituto de Investigaciones en Reproducción, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Dipak Kumar Sarkar
- Endocrine Program, Department of Animal Sciences, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, United States of America
| | - Daniel Pisera
- Facultad de Medicina, Instituto de Investigaciones en Reproducción, Universidad de Buenos Aires, Buenos Aires, Argentina
- * E-mail:
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Tagliati F, Gentilin E, Buratto M, Molè D, degli Uberti EC, Zatelli MC. Magmas, a gene newly identified as overexpressed in human and mouse ACTH-secreting pituitary adenomas, protects pituitary cells from apoptotic stimuli. Endocrinology 2010; 151:4635-42. [PMID: 20719856 DOI: 10.1210/en.2010-0441] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Pituitary tumors are mostly benign, being locally invasive in 5-35% of cases. Deregulation of several genes has been suggested as a possible alteration underlying the development and progression of pituitary tumors. We here report the identification of a cDNA, corresponding to Magmas gene (mitochondria-associated protein involved in granulocyte-macrophage colony-stimulating factor signal transduction), which is highly expressed in two different ACTH-secreting mouse pituitary adenoma cell lines as compared with normal pituitary as well as in two thirds of 64 examined pituitary adenomas as compared with human normal pituitary. Tim 16, the mitochondrial protein encoded by Magmas, was indeed expressed in a mouse ACTH-secreting pituitary adenoma cell line, AtT-20 D16v-F2 cells, in a subcellular compartment likely corresponding to mitochondria. Magmas silencing determined a reduced rate of DNA synthesis, an accumulation in G1 phase, and a concomitant decrease in S phase in At-T20 D16v-F2 cells. Moreover, Magmas-silenced cells displayed basal caspase 3/7 activity and DNA fragmentation levels similar to control cells, which both increased under proapoptotic stimuli. Our data demonstrate that Magmas is overexpressed in mouse and human ACTH-secreting pituitary adenomas. Moreover, our results show that Magmas protects pituitary cells from apoptosis, suggesting its possible involvement in neoplastic transformation.
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Affiliation(s)
- Federico Tagliati
- Section of Endocrinology, Department of Biomedical Sciences and Advanced Therapies, University of Ferrara, Via Savonarola 9, I-44100 Ferrara, Italy
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Grozinsky-Glasberg S, Shimon I. The potential role of mTOR inhibitors in the treatment of endocrine tumors. J Endocrinol Invest 2010; 33:276-81. [PMID: 20503485 DOI: 10.1007/bf03345792] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Mammalian target of rapamycin (mTOR), a main protein kinase in the phosphoinositide 3-kinase/Akt/p70S6K signaling pathway, is an important intracellular mediator involved in multiple cellular functions including proliferation, differentiation, apoptosis, longevity, tumorigenesis, and angiogenesis. Alterations of the normal activity of mTOR and of mTOR-related kinases in this pathway have been found in a diversity of human tumors, suggesting that mTOR may be an attractive target for the development of new anti-cancer therapies. The main objective of this article is to summarize the available pre-clinical and clinical data regarding a possible role of mTOR inhibitors in the treatment of different endocrine cancers.
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Affiliation(s)
- S Grozinsky-Glasberg
- Institute of Endocrinology and Felsenstein Research Center, Beilinson Hospital, Rabin Medical Center, Petah Tiqva, Israel
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