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Milewska-Kranc A, Ćwikła JB, Kolasinska-Ćwikła A. The Role of Receptor-Ligand Interaction in Somatostatin Signaling Pathways: Implications for Neuroendocrine Tumors. Cancers (Basel) 2023; 16:116. [PMID: 38201544 PMCID: PMC10778465 DOI: 10.3390/cancers16010116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 12/19/2023] [Accepted: 12/22/2023] [Indexed: 01/12/2024] Open
Abstract
Neuroendocrine tumors (NETs) arise from neuroendocrine cells and manifest in diverse organs. Key players in their regulation are somatostatin and its receptors (SSTR1-SSTR5). Understanding receptor-ligand interactions and signaling pathways is vital for elucidating their role in tumor development and therapeutic potential. This review highlights SSTR characteristics, localization, and expression in tissues, impacting physiological functions. Mechanisms of somatostatin and synthetic analogue binding to SSTRs, their selectivity, and their affinity were analyzed. Upon activation, somatostatin initiates intricate intracellular signaling, involving cAMP, PLC, and MAP kinases and influencing growth, differentiation, survival, and hormone secretion in NETs. This review explores SSTR expression in different tumor types, examining receptor activation effects on cancer cells. SSTRs' significance as therapeutic targets is discussed. Additionally, somatostatin and analogues' role in hormone secretion regulation, tumor growth, and survival is emphasized, presenting relevant therapeutic examples. In conclusion, this review advances the knowledge of receptor-ligand interactions and signaling pathways in somatostatin receptors, with potential for improved neuroendocrine tumor treatments.
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Affiliation(s)
| | - Jarosław B. Ćwikła
- School of Medicine, University of Warmia and Mazury, Aleja Warszawska 30, 10-082 Olsztyn, Poland
- Diagnostic Therapeutic Center–Gammed, Lelechowska 5, 02-351 Warsaw, Poland
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2
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Khalid E, Chang JP. Receptor-proximal effectors mediating GnRH actions in the goldfish pituitary: Involvement of G protein subunits and GRKs. Gen Comp Endocrinol 2022; 319:113991. [PMID: 35157923 DOI: 10.1016/j.ygcen.2022.113991] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 02/01/2022] [Accepted: 02/09/2022] [Indexed: 11/21/2022]
Abstract
In goldfish (Carassius auratus), two endogenous isoforms of gonadotropin-releasing hormone (GnRH) stimulate luteinizing hormone (LH) and growth hormone (GH) secretion. These isoforms, GnRH2 and GnRH3, act on a shared population of cell-surface GnRH receptors (GnRHRs) expressed on both gonadotrophs and somatotrophs, and can signal through unique, yet partially overlapping, suites of intracellular effectors, in a phenomenon known as functional selectivity or biased signalling. In this study, G-protein alpha (Gα) subunits were targeted with two inhibitors, YM-254890 and BIM-46187, to ascertain the contribution of specific G-protein subunits in GnRH signalling. Results with the Gαq/11-specific inhibitor YM-254890 on primary cultures of goldfish pituitary cells revealed the use of these subunits in GnRH control of both LH and GH release, as well as GnRH-induced elevations in phospho-ERK levels. Results with the pan-Gα inhibitor BIM-46187 matched those using YM-254890 in LH release but GH responses differed, indicating additional, non-Gαq/11 subunits may be involved in somatotrophs. BIM-46187 also elevated unstimulated LH and GH release suggesting that Gα subunits regulate basal hormone secretion. Furthermore, G-protein-coupled receptor kinase (GRK2/3) inhibition reduced LH responses to GnRH2 and GnRH3, and selectively enhanced GnRH2-stimulated GH release, indicating differential use of GRK2/3 in GnRH actions on gonadotrophs and somatotrophs. These findings in a primary untransformed system provide the first direct evidence to establish Gαq/11 as an obligate driver of GnRH signalling in goldfish pituitary cells, and additionally describe the differential agonist- and cell type-selective involvement of GRK2/3 in this system.
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Affiliation(s)
- Enezi Khalid
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G2E9, Canada
| | - John P Chang
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G2E9, Canada.
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3
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Madan A, Markison S, Betz SF, Krasner A, Luo R, Jochelson T, Lickliter J, Struthers RS. Paltusotine, a novel oral once-daily nonpeptide SST2 receptor agonist, suppresses GH and IGF-1 in healthy volunteers. Pituitary 2022; 25:328-339. [PMID: 35000098 PMCID: PMC8894159 DOI: 10.1007/s11102-021-01201-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 12/08/2021] [Indexed: 01/28/2023]
Abstract
PURPOSE Evaluate the pharmacodynamics, pharmacokinetics, and safety of paltusotine, an orally bioavailable, nonpeptide, somatostatin receptor subtype 2 (SST2) agonist being developed for the treatment of acromegaly and neuroendocrine tumors. METHODS A randomized, double-blind, placebo-controlled, single center, single and multiple ascending dose phase 1 study was conducted in healthy male volunteers who received (i) single-dose of oral paltusotine 1.25, 2.5, 5, 10, and 20 mg (solution); and 40 and 60 mg (capsules) or (ii) multiple-dose oral paltusotine capsules once daily 5 mg (× 7 days), 10, 20, and 30 mg (× 10 days). Main outcome measures were pharmacodynamics (changes in growth hormone-releasing hormone [GHRH] stimulated growth hormone [GH] and insulin-like growth factor 1 [IGF-1]), pharmacokinetics, safety, and tolerability. RESULTS Single-dose cohorts: n = 41 active, n = 14 placebo. Multiple-dose cohorts: n = 24 active, n = 12 placebo. Paltusotine was well tolerated, orally bioavailable, associated with increased plasma concentrations to doses up to 40 mg, and was eliminated with a half-life of approximately 30 h. Single-dose paltusotine 1.25 to 20 mg suppressed GHRH-stimulated GH secretion by 44% to 93% compared to 15% with placebo. Multiple-dose paltusotine 5 to 30 mg administered once daily for 10 days suppressed IGF-1 by 19% to 37% compared to an increase of 2.4% with placebo. CONCLUSIONS Paltusotine suppresses GH and IGF-1 in a dose-dependent fashion, with a safety profile similar to currently approved SST2 receptor ligands. Paltusotine is a promising once-daily oral nonpeptide SST2 agonist candidate for managing acromegaly and neuroendocrine tumors. TRIAL REGISTRATION NCT03276858, registered September 8, 2017, retrospectively registered.
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Affiliation(s)
- Ajay Madan
- Crinetics Pharmaceuticals, Inc, 10222 Barnes Canyon Road, Building 2, San Diego, CA, 92121, USA.
- Crinetics Medical Affairs, Crinetics Pharmaceuticals, Inc, 10222 Barnes Canyon Rd. Bldg.2, San Diego, CA, 92121, USA.
| | - Stacy Markison
- Crinetics Pharmaceuticals, Inc, 10222 Barnes Canyon Road, Building 2, San Diego, CA, 92121, USA
| | - Stephen F Betz
- Crinetics Pharmaceuticals, Inc, 10222 Barnes Canyon Road, Building 2, San Diego, CA, 92121, USA
| | - Alan Krasner
- Crinetics Pharmaceuticals, Inc, 10222 Barnes Canyon Road, Building 2, San Diego, CA, 92121, USA
| | - Rosa Luo
- Crinetics Pharmaceuticals, Inc, 10222 Barnes Canyon Road, Building 2, San Diego, CA, 92121, USA
| | - Theresa Jochelson
- Crinetics Pharmaceuticals, Inc, 10222 Barnes Canyon Road, Building 2, San Diego, CA, 92121, USA
| | | | - R Scott Struthers
- Crinetics Pharmaceuticals, Inc, 10222 Barnes Canyon Road, Building 2, San Diego, CA, 92121, USA
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4
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Treppiedi D, Marra G, Di Muro G, Catalano R, Mangili F, Esposito E, Calebiro D, Arosio M, Peverelli E, Mantovani G. Dimerization of GPCRs: Novel insight into the role of FLNA and SSAs regulating SST 2 and SST 5 homo- and hetero-dimer formation. Front Endocrinol (Lausanne) 2022; 13:892668. [PMID: 35992099 PMCID: PMC9389162 DOI: 10.3389/fendo.2022.892668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Accepted: 07/08/2022] [Indexed: 11/13/2022] Open
Abstract
The process of GPCR dimerization can have profound effects on GPCR activation, signaling, and intracellular trafficking. Somatostatin receptors (SSTs) are class A GPCRs abundantly expressed in pituitary tumors where they represent the main pharmacological targets of somatostatin analogs (SSAs), thanks to their antisecretory and antiproliferative actions. The cytoskeletal protein filamin A (FLNA) directly interacts with both somatostatin receptor type 2 (SST2) and 5 (SST5) and regulates their expression and signaling in pituitary tumoral cells. So far, the existence and physiological relevance of SSTs homo- and hetero-dimerization in the pituitary have not been explored. Moreover, whether octreotide or pasireotide may play modulatory effects and whether FLNA may participate to this level of receptor organization have remained elusive. Here, we used a proximity ligation assay (PLA)-based approach for the in situ visualization and quantification of SST2/SST5 dimerization in rat GH3 as well as in human melanoma cells either expressing (A7) or lacking (M2) FLNA. First, we observed the formation of endogenous SST5 homo-dimers in GH3, A7, and M2 cells. Using the PLA approach combined with epitope tagging, we detected homo-dimers of human SST2 in GH3, A7, and M2 cells transiently co-expressing HA- and SNAP-tagged SST2. SST2 and SST5 can also form endogenous hetero-dimers in these cells. Interestingly, FLNA absence reduced the basal number of hetero-dimers (-36.8 ± 6.3% reduction of PLA events in M2, P < 0.05 vs. A7), and octreotide but not pasireotide promoted hetero-dimerization in both A7 and M2 (+20.0 ± 11.8% and +44.1 ± 16.3% increase of PLA events in A7 and M2, respectively, P < 0.05 vs. basal). Finally, immunofluorescence data showed that SST2 and SST5 recruitment at the plasma membrane and internalization are similarly induced by octreotide and pasireotide in GH3 and A7 cells. On the contrary, in M2 cells, octreotide failed to internalize both receptors whereas pasireotide promoted robust receptor internalization at shorter times than in A7 cells. In conclusion, we demonstrated that in GH3 cells SST2 and SST5 can form both homo- and hetero-dimers and that FLNA plays a role in the formation of SST2/SST5 hetero-dimers. Moreover, we showed that FLNA regulates SST2 and SST5 intracellular trafficking induced by octreotide and pasireotide.
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Affiliation(s)
- Donatella Treppiedi
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Giusy Marra
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Genesio Di Muro
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
- University Sapienza of Rome, Rome, Italy
| | - Rosa Catalano
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Federica Mangili
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Emanuela Esposito
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Davide Calebiro
- Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, United Kingdom
- Centre of Membrane Proteins and Receptors, Universities of Birmingham and Nottingham, Birmingham, United Kingdom
| | - Maura Arosio
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
- Endocrinology Unit, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Ca’ Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Erika Peverelli
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
- *Correspondence: Erika Peverelli,
| | - Giovanna Mantovani
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
- Endocrinology Unit, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Ca’ Granda Ospedale Maggiore Policlinico, Milan, Italy
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5
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Somatostatin-Dopamine Chimeric Molecules in Neuroendocrine Neoplasms. J Clin Med 2021; 10:jcm10030501. [PMID: 33535394 PMCID: PMC7867079 DOI: 10.3390/jcm10030501] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 01/25/2021] [Accepted: 01/26/2021] [Indexed: 12/12/2022] Open
Abstract
Neuroendocrine neoplasms (NENs) are a widely heterogeneous family of neoplasms arising from neuroendocrine cells, which are interspersed throughout the body. Despite NENs are relatively rare, their incidence and prevalence are constantly increasing probably due to the improvement in earlier diagnosis and patients’ management. When surgery is not curative, particularly for patients with metastatic disease, several medical options are available. Somatostatin analogues (SSA) are the first-line medical therapy for well-differentiated NENs. Interestingly, the heterodimerization of somatostatin receptors (SSTs) with dopamine receptors (DRs) has been discovered in NENs. This phenomenon results in hybrid receptors with enhanced functional activity. On these bases, chimeric molecules embracing somatostatin and dopamine features have been recently developed. The aim of this review is to provide a comprehensive overview of the available preclinical and clinical data regarding chimeric somatostatin-dopamine agonists as a new class of “magic bullet” in the therapy of NENs.
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6
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Kántás B, Szőke É, Börzsei R, Bánhegyi P, Asghar J, Hudhud L, Steib A, Hunyady Á, Horváth Á, Kecskés A, Borbély É, Hetényi C, Pethő G, Pintér E, Helyes Z. In Silico, In Vitro and In Vivo Pharmacodynamic Characterization of Novel Analgesic Drug Candidate Somatostatin SST 4 Receptor Agonists. Front Pharmacol 2021; 11:601887. [PMID: 33815096 PMCID: PMC8015869 DOI: 10.3389/fphar.2020.601887] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 11/30/2020] [Indexed: 11/26/2022] Open
Abstract
Background: Somatostatin released from the capsaicin-sensitive sensory nerves mediates analgesic and anti-inflammatory effects via its receptor subtype 4 (SST4) without influencing endocrine functions. Therefore, SST4 is considered to be a novel target for drug development in pain, especially chronic neuropathy which is a great unmet medical need. Purpose and Experimental Approach: Here, we examined the in silico binding, SST4-linked G protein activation and β-arrestin activation on stable SST4 expressing cells and the effects of our novel pyrrolo-pyrimidine molecules (20, 100, 500, 1,000, 2,000 µg·kg−1) on partial sciatic nerve ligation-induced traumatic mononeuropathic pain model in mice. Key Results: The novel compounds bind to the high affinity binding site of SST4 the receptor and activate the G protein. However, unlike the reference SST4 agonists NNC 26-9100 and J-2156, they do not induce β-arrestin activation responsible for receptor desensitization and internalization upon chronic use. They exert 65–80% maximal anti-hyperalgesic effects in the neuropathy model 1 h after a single oral administration of 100–500 µg·kg−1 doses. Conclusion and Implications: The novel orally active compounds show potent and effective SST4 receptor agonism in vitro and in vivo. All four novel ligands proved to be full agonists based on G protein activation, but failed to recruit β-arrestin. Based on their potent antinociceptive effect in the neuropathic pain model following a single oral administration, they are promising candidates for drug development.
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Affiliation(s)
- Boglárka Kántás
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Pécs, Hungary.,János Szentágothai Research Center and Center for Neuroscience, University of Pécs, Pécs, Hungary
| | - Éva Szőke
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Pécs, Hungary.,János Szentágothai Research Center and Center for Neuroscience, University of Pécs, Pécs, Hungary.,PharmInVivo Ltd., Pécs, Hungary
| | - Rita Börzsei
- Department of Pharmacology, Faculty of Pharmacy, University of Pécs, Pécs, Hungary
| | | | - Junaid Asghar
- Gomal Centre of Pharmaceutical Sciences, Gomal University, Khyber Pakhtoonkhwa, Pakistan
| | - Lina Hudhud
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Pécs, Hungary.,János Szentágothai Research Center and Center for Neuroscience, University of Pécs, Pécs, Hungary
| | - Anita Steib
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Pécs, Hungary.,János Szentágothai Research Center and Center for Neuroscience, University of Pécs, Pécs, Hungary
| | - Ágnes Hunyady
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Pécs, Hungary.,János Szentágothai Research Center and Center for Neuroscience, University of Pécs, Pécs, Hungary
| | - Ádám Horváth
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Pécs, Hungary.,János Szentágothai Research Center and Center for Neuroscience, University of Pécs, Pécs, Hungary
| | - Angéla Kecskés
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Pécs, Hungary.,János Szentágothai Research Center and Center for Neuroscience, University of Pécs, Pécs, Hungary
| | - Éva Borbély
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Pécs, Hungary.,János Szentágothai Research Center and Center for Neuroscience, University of Pécs, Pécs, Hungary
| | - Csaba Hetényi
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Pécs, Hungary.,János Szentágothai Research Center and Center for Neuroscience, University of Pécs, Pécs, Hungary
| | - Gábor Pethő
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Pécs, Hungary.,Department of Pharmacology, Faculty of Pharmacy, University of Pécs, Pécs, Hungary
| | - Erika Pintér
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Pécs, Hungary.,János Szentágothai Research Center and Center for Neuroscience, University of Pécs, Pécs, Hungary.,PharmInVivo Ltd., Pécs, Hungary.,Algonist Biotechnolgies GmbH, Vienna, Austria
| | - Zsuzsanna Helyes
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Pécs, Hungary.,János Szentágothai Research Center and Center for Neuroscience, University of Pécs, Pécs, Hungary.,PharmInVivo Ltd., Pécs, Hungary.,Algonist Biotechnolgies GmbH, Vienna, Austria
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7
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Abstract
Acromegaly is a systemic disease associated with increased morbidity and mortality. Most of these comorbidities can be prevented or delayed with adequate disease treatment. Although three modalities of treatment (surgery, medical treatment, and radiotherapy) are available and new drugs were approved in the last decades, there are still some patients that maintain disease activity despite treatment. Therefore, there is a need for novel therapies for acromegaly and for that purpose new formulations of currently used drugs and also new drugs are currently under study. In this review, we summarize the novel therapies for acromegaly.
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Affiliation(s)
- Bernardo Maia
- Neuroendocrinology Research Center/Endocrinology Division – Medical School and Hospital Universitário Clementino Fraga Filho – Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Leandro Kasuki
- Neuroendocrinology Research Center/Endocrinology Division – Medical School and Hospital Universitário Clementino Fraga Filho – Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
- Neuroendocrinology Division – Instituto Estadual do Cérebro Paulo Niemeyer, Rio de Janeiro, Brazil
- Endocrinology Division – Hospital Federal de Bonsucesso, Rio de Janeiro Brazil
| | - Mônica R Gadelha
- Neuroendocrinology Research Center/Endocrinology Division – Medical School and Hospital Universitário Clementino Fraga Filho – Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
- Neuroendocrinology Division – Instituto Estadual do Cérebro Paulo Niemeyer, Rio de Janeiro, Brazil
- Neuropatology and Molecular Genetics Laboratory – Instituto Estadual do Cérebro Paulo Niemeyer, Rio de Janeiro, Brazil
- Correspondence should be addressed to M R Gadelha:
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8
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Biological and Biochemical Basis of the Differential Efficacy of First and Second Generation Somatostatin Receptor Ligands in Neuroendocrine Neoplasms. Int J Mol Sci 2019; 20:ijms20163940. [PMID: 31412614 PMCID: PMC6720449 DOI: 10.3390/ijms20163940] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/1970] [Revised: 08/05/2019] [Accepted: 08/08/2019] [Indexed: 02/07/2023] Open
Abstract
Endogenous somatostatin shows anti-secretory effects in both physiological and pathological settings, as well as inhibitory activity on cell growth. Since somatostatin is not suitable for clinical practice, researchers developed synthetic somatostatin receptor ligands (SRLs) to overcome this limitation. Currently, SRLs represent pivotal tools in the treatment algorithm of neuroendocrine tumors (NETs). Octreotide and lanreotide are the first-generation SRLs developed and show a preferential binding affinity to somatostatin receptor (SST) subtype 2, while pasireotide, which is a second-generation SRL, has high affinity for multiple SSTs (SST5 > SST2 > SST3 > SST1). A number of studies demonstrated that first-generation and second-generation SRLs show distinct functional properties, besides the mere receptor affinity. Therefore, the aim of the present review is to critically review the current evidence on the biological effects of SRLs in pituitary adenomas and neuroendocrine tumors, by mainly focusing on the differences between first-generation and second-generation ligands.
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9
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BIM-23A760 influences key functional endpoints in pituitary adenomas and normal pituitaries: molecular mechanisms underlying the differential response in adenomas. Sci Rep 2017; 7:42002. [PMID: 28181484 PMCID: PMC5299479 DOI: 10.1038/srep42002] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 01/06/2017] [Indexed: 01/02/2023] Open
Abstract
Chimeric somatostatin/dopamine compounds such as BIM-23A760, an sst2/sst5/D2 receptors-agonist, have emerged as promising new approaches to treat pituitary adenomas. However, information on direct in vitro effects of BIM-23A760 in normal and tumoral pituitaries remains incomplete. The objective of this study was to analyze BIM-23A760 effects on functional parameters (Ca2+ signaling, hormone expression/secretion, cell viability and apoptosis) in pituitary adenomas (n = 74), and to compare with the responses of normal primate and human pituitaries (n = 3–5). Primate and human normal pituitaries exhibited similar sst2/sst5/D2 expression patterns, wherein BIM-23A760 inhibited the expression/secretion of several pituitary hormones (specially GH/PRL), which was accompanied by increased sst2/sst5/D2 expression in primates and decreased Ca2+ concentration in human cells. In tumoral pituitaries, BIM-23A760 also inhibited Ca2+ concentration, hormone secretion/expression and proliferation. However, BIM-23A760 elicited stimulatory effects in a subset of GHomas, ACTHomas and NFPAs in terms of Ca2+ signaling and/or hormone secretion, which was associated with the relative somatostatin/dopamine-receptors levels, especially sst5 and sst5TMD4. The chimeric sst2/sst5/D2 compound BIM-23A760 affects multiple, clinically relevant parameters on pituitary adenomas and may represent a valuable therapeutic tool. The relative ssts/D2 expression profile, particularly sst5 and/or sst5TMD4 levels, might represent useful molecular markers to predict the ultimate response of pituitary adenomas to BIM-23A760.
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10
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Ibáñez-Costa A, Rivero-Cortés E, Vázquez-Borrego MC, Gahete MD, Jiménez-Reina L, Venegas-Moreno E, de la Riva A, Arráez MÁ, González-Molero I, Schmid HA, Maraver-Selfa S, Gavilán-Villarejo I, García-Arnés JA, Japón MA, Soto-Moreno A, Gálvez MA, Luque RM, Castaño JP. Octreotide and pasireotide (dis)similarly inhibit pituitary tumor cells in vitro. J Endocrinol 2016; 231:135-145. [PMID: 27587848 DOI: 10.1530/joe-16-0332] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Accepted: 09/01/2016] [Indexed: 02/01/2023]
Abstract
Somatostatin analogs (SSA) are the mainstay of pharmacological treatment for pituitary adenomas. However, some patients escape from therapy with octreotide, a somatostatin receptor 2 (sst2)-preferring SSA, and pasireotide, a novel multi-sst-preferring SSA, may help to overcome this problem. It has been proposed that correspondence between sst1-sst5 expression pattern and SSA-binding profile could predict patient's response. To explore the cellular/molecular features associated with octreotide/pasireotide response, we performed a parallel comparison of their in vitro effects, evaluating sst1-sst5 expression, intracellular Ca2+ signaling ([Ca2+]i), hormone secretion and cell viability, in a series of 85 pituitary samples. Somatotropinomas expressed sst5>sst2, yet octreotide reduced [Ca2+]i more efficiently than pasireotide, while both SSA similarly decreased growth hormone release/expression and viability. Corticotropinomas predominantly expressed sst5, but displayed limited response to pasireotide, while octreotide reduced functional endpoints. Non-functioning adenomas preferentially expressed sst3 but, surprisingly, both SSA increased cell viability. Prolactinomas mainly expressed sst1 but were virtually unresponsive to SSA. Finally, both SSA decreased [Ca2+]i in normal pituitaries. In conclusion, both SSA act in vitro on pituitary adenomas exerting both similar and distinct effects; however, no evident correspondence was found with the sst1-sst5 profile. Thus, it seems plausible that additional factors, besides the simple abundance of a given sst, critically influence the SSA response.
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Affiliation(s)
- Alejandro Ibáñez-Costa
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC)Córdoba, Spain
- Department of Cell BiologyPhysiology and Immunology, Universidad de Córdoba, Córdoba, Spain
- Hospital Universitario Reina SofíaCórdoba, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERObn)Córdoba, Spain
| | - Esther Rivero-Cortés
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC)Córdoba, Spain
- Department of Cell BiologyPhysiology and Immunology, Universidad de Córdoba, Córdoba, Spain
- Hospital Universitario Reina SofíaCórdoba, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERObn)Córdoba, Spain
| | - Mari C Vázquez-Borrego
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC)Córdoba, Spain
- Department of Cell BiologyPhysiology and Immunology, Universidad de Córdoba, Córdoba, Spain
- Hospital Universitario Reina SofíaCórdoba, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERObn)Córdoba, Spain
| | - Manuel D Gahete
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC)Córdoba, Spain
- Department of Cell BiologyPhysiology and Immunology, Universidad de Córdoba, Córdoba, Spain
- Hospital Universitario Reina SofíaCórdoba, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERObn)Córdoba, Spain
| | - Luis Jiménez-Reina
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC)Córdoba, Spain
- Department of Morphological SciencesUniversidad de Córdoba, Córdoba, Spain
| | - Eva Venegas-Moreno
- Metabolism and Nutrition UnitHospital Universitario Virgen del Rocío, Instituto de Biomedicina de Sevilla (IBIS), Seville, Spain
| | - Andrés de la Riva
- Service of NeurosurgeryHospital Universitario Reina Sofía, Córdoba, Spain
| | | | | | - Herbert A Schmid
- Novartis Pharma AGNovartis Institutes for Biomedical Research, Oncology, CH-4057 Basel, Switzerland
| | - Silvia Maraver-Selfa
- Service of Endocrinology and NutritionHospital Clínico Universitario Virgen de la Victoria, Málaga, Spain
| | | | | | - Miguel A Japón
- Department of PathologyHospital Universitario Virgen del Rocío, Seville, Spain
| | - Alfonso Soto-Moreno
- Metabolism and Nutrition UnitHospital Universitario Virgen del Rocío, Instituto de Biomedicina de Sevilla (IBIS), Seville, Spain
| | - María A Gálvez
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC)Córdoba, Spain
- Service of Endocrinology and NutritionHospital Universitario Reina Sofía, Córdoba, Spain
| | - Raúl M Luque
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC)Córdoba, Spain
- Department of Cell BiologyPhysiology and Immunology, Universidad de Córdoba, Córdoba, Spain
- Hospital Universitario Reina SofíaCórdoba, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERObn)Córdoba, Spain
| | - Justo P Castaño
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC)Córdoba, Spain
- Department of Cell BiologyPhysiology and Immunology, Universidad de Córdoba, Córdoba, Spain
- Hospital Universitario Reina SofíaCórdoba, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERObn)Córdoba, Spain
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11
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Berardi R, Morgese F, Torniai M, Savini A, Partelli S, Rinaldi S, Caramanti M, Ferrini C, Falconi M, Cascinu S. Medical treatment for gastro-entero-pancreatic neuroendocrine tumours. World J Gastrointest Oncol 2016; 8:389-401. [PMID: 27096034 PMCID: PMC4824717 DOI: 10.4251/wjgo.v8.i4.389] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2015] [Accepted: 02/16/2016] [Indexed: 02/05/2023] Open
Abstract
Gastro-entero-pancreatic neuroendocrine neoplasms (GEP-NENs) represents a various family of rare tumours. Surgery is the first choice in GEP-NENs patients with localized disease whilst in the metastatic setting many other treatment options are available. Somatostatin analogues are indicated for symptoms control in functioning tumours. Furthermore they may be effective to inhibit tumour progression. GEP-NENs pathogenesis has been extensively studied in the last years therefore several driver mutations pathway genes have been identified as crucial factors in their tumourigenesis. GEP-NENs can over-express vascular endothelial growth factor (VEGF), basic-fibroblastic growth factor, transforming growth factor (TGF-α and -β), platelet derived growth factor (PDGF), insulin-like growth factor-1 (IGF-1) and their receptors PDGF receptor, IGF-1 receptor, epidermal growth factor receptor, VEGF receptor, and c-kit (stem cell factor receptor) that can be considered as potential targets. The availability of new targeted agents, such as everolimus and sunitinib that are effective in advanced and metastatic pancreatic neuroendocrine tumours, has provided new treatment opportunities. Many trials combing new drugs are ongoing.
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12
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Cives M, Strosberg J. The Expanding Role of Somatostatin Analogs in Gastroenteropancreatic and Lung Neuroendocrine Tumors. Drugs 2015; 75:847-58. [DOI: 10.1007/s40265-015-0397-7] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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13
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Schulz S, Lehmann A, Kliewer A, Nagel F. Fine-tuning somatostatin receptor signalling by agonist-selective phosphorylation and dephosphorylation: IUPHAR Review 5. Br J Pharmacol 2014; 171:1591-9. [PMID: 24328848 PMCID: PMC3966740 DOI: 10.1111/bph.12551] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Revised: 10/08/2013] [Accepted: 10/31/2013] [Indexed: 12/28/2022] Open
Abstract
The biological actions of somatostatin are mediated by a family of five GPCRs, named sst1 to sst5 . Somatostatin receptors exhibit equally high-binding affinities to their natural ligand somatostatin-14 and largely overlapping distributions. The overexpression of somatostatin receptors in human tumours is the molecular basis for diagnostic and therapeutic application of the stable somatostatin analogues octreotide, lanreotide and pasireotide. The efficiency of somatostatin receptor signalling is tightly regulated and ultimately limited by the coordinated phosphorylation and dephosphorylation of intracellular carboxyl-terminal serine and threonine residues. Here, we review and discuss recent progress in the generation and application of phosphosite-specific antibodies for human sst2 and sst5 receptors. These phosphosite-specific antibodies are unique tools to monitor the spatial and temporal dynamics of receptors phosphorylation and dephosphorylation. Using a combined approach of phosphosite-specific antibodies and siRNA knock-down screening, relevant kinases and phosphatases were identified. Emerging evidence suggests distinct mechanisms of agonist-selective fine-tuning for individual somatostatin receptors. The recently uncovered differences in phosphorylation and dephosphorylation of these receptors may hence be of physiological significance in mediating responses to acute, persistent or repeated stimuli in a variety of target tissues.
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Affiliation(s)
- Stefan Schulz
- Institute of Pharmacology and Toxicology, Jena University Hospital, Friedrich-Schiller-UniversityJena, Germany
| | - Andreas Lehmann
- Institute of Pharmacology and Toxicology, Jena University Hospital, Friedrich-Schiller-UniversityJena, Germany
| | - Andrea Kliewer
- Institute of Pharmacology and Toxicology, Jena University Hospital, Friedrich-Schiller-UniversityJena, Germany
| | - Falko Nagel
- Institute of Pharmacology and Toxicology, Jena University Hospital, Friedrich-Schiller-UniversityJena, Germany
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14
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Barbieri F, Albertelli M, Grillo F, Mohamed A, Saveanu A, Barlier A, Ferone D, Florio T. Neuroendocrine tumors: insights into innovative therapeutic options and rational development of targeted therapies. Drug Discov Today 2014; 19:458-68. [DOI: 10.1016/j.drudis.2013.10.015] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Revised: 09/02/2013] [Accepted: 10/21/2013] [Indexed: 02/07/2023]
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15
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Chalabi M, Duluc C, Caron P, Vezzosi D, Guillermet-Guibert J, Pyronnet S, Bousquet C. Somatostatin analogs: does pharmacology impact antitumor efficacy? Trends Endocrinol Metab 2014; 25:115-27. [PMID: 24405892 DOI: 10.1016/j.tem.2013.11.003] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 11/05/2013] [Accepted: 11/15/2013] [Indexed: 01/17/2023]
Abstract
Somatostatin is an endogenous inhibitor of secretion and cell proliferation. These features render somatostatin a logical candidate for the management of neuroendocrine tumors that express somatostatin receptors. Synthetic somatostatin analogs (SSAs) have longer half-lives than somatostatin, but have similar activities, and are used for the treatment of these types of disorders. Interest has focused on novel multireceptor analogs with broader affinity to several of the five somatostatin receptors, thereby presenting putatively higher antitumor activities. Recent evidence indicates that SSAs cannot be considered mimics of native somatostatin in regulating signaling pathways downstream of receptors. Here we review this knowledge, discuss the concept of biased agonism, and highlight what considerations need to be taken into account for the optimal clinical use of SSAs.
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Affiliation(s)
- Mounira Chalabi
- Institut National de la Santé et de la Recherche Médicale (INSERM), Unité Mixte de Recherche (UMR) 1037, Centre de Recherche en Cancérologie de Toulouse (CRCT), Equipe labellisée Ligue Contre le Cancer and Laboratoire d'Excellence Toulouse Cancer (TOUCAN), 31432 Toulouse, France; Université Toulouse III Paul Sabatier, 31062 Toulouse, France
| | - Camille Duluc
- Institut National de la Santé et de la Recherche Médicale (INSERM), Unité Mixte de Recherche (UMR) 1037, Centre de Recherche en Cancérologie de Toulouse (CRCT), Equipe labellisée Ligue Contre le Cancer and Laboratoire d'Excellence Toulouse Cancer (TOUCAN), 31432 Toulouse, France; Université Toulouse III Paul Sabatier, 31062 Toulouse, France
| | - Philippe Caron
- Institut National de la Santé et de la Recherche Médicale (INSERM), Unité Mixte de Recherche (UMR) 1037, Centre de Recherche en Cancérologie de Toulouse (CRCT), Equipe labellisée Ligue Contre le Cancer and Laboratoire d'Excellence Toulouse Cancer (TOUCAN), 31432 Toulouse, France; Université Toulouse III Paul Sabatier, 31062 Toulouse, France; Service d'Endocrinologie et Maladies Métaboliques, Pôle Cardio-Vasculaire et Métabolique, Centre Hospitalier Universitaire (CHU) Larrey, 31059 Toulouse, France
| | - Delphine Vezzosi
- Institut National de la Santé et de la Recherche Médicale (INSERM), Unité Mixte de Recherche (UMR) 1037, Centre de Recherche en Cancérologie de Toulouse (CRCT), Equipe labellisée Ligue Contre le Cancer and Laboratoire d'Excellence Toulouse Cancer (TOUCAN), 31432 Toulouse, France; Université Toulouse III Paul Sabatier, 31062 Toulouse, France; Service d'Endocrinologie et Maladies Métaboliques, Pôle Cardio-Vasculaire et Métabolique, Centre Hospitalier Universitaire (CHU) Larrey, 31059 Toulouse, France
| | - Julie Guillermet-Guibert
- Institut National de la Santé et de la Recherche Médicale (INSERM), Unité Mixte de Recherche (UMR) 1037, Centre de Recherche en Cancérologie de Toulouse (CRCT), Equipe labellisée Ligue Contre le Cancer and Laboratoire d'Excellence Toulouse Cancer (TOUCAN), 31432 Toulouse, France; Université Toulouse III Paul Sabatier, 31062 Toulouse, France
| | - Stéphane Pyronnet
- Institut National de la Santé et de la Recherche Médicale (INSERM), Unité Mixte de Recherche (UMR) 1037, Centre de Recherche en Cancérologie de Toulouse (CRCT), Equipe labellisée Ligue Contre le Cancer and Laboratoire d'Excellence Toulouse Cancer (TOUCAN), 31432 Toulouse, France; Université Toulouse III Paul Sabatier, 31062 Toulouse, France
| | - Corinne Bousquet
- Institut National de la Santé et de la Recherche Médicale (INSERM), Unité Mixte de Recherche (UMR) 1037, Centre de Recherche en Cancérologie de Toulouse (CRCT), Equipe labellisée Ligue Contre le Cancer and Laboratoire d'Excellence Toulouse Cancer (TOUCAN), 31432 Toulouse, France; Université Toulouse III Paul Sabatier, 31062 Toulouse, France.
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16
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Reubi JC, Schonbrunn A. Illuminating somatostatin analog action at neuroendocrine tumor receptors. Trends Pharmacol Sci 2013; 34:676-88. [PMID: 24183675 DOI: 10.1016/j.tips.2013.10.001] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 09/26/2013] [Accepted: 10/03/2013] [Indexed: 02/08/2023]
Abstract
Somatostatin analogs for the diagnosis and therapy of neuroendocrine tumors (NETs) have been used in clinical applications for more than two decades. Five somatostatin receptor subtypes have been identified and molecular mechanisms of somatostatin receptor signaling and regulation have been elucidated. These advances increased understanding of the biological role of each somatostatin receptor subtype, their distribution in NETs, as well as agonist-specific regulation of receptor signaling, internalization, and phosphorylation, particularly for the sst2 receptor subtype, which is the primary target of current somatostatin analog therapy for NETs. Various hypotheses exist to explain differences in patient responsiveness to somatostatin analog inhibition of tumor secretion and growth as well as differences in the development of tumor resistance to therapy. In addition, we now have a better understanding of the action of both first generation (octreotide, lanreotide, Octreoscan) and second generation (pasireotide) FDA-approved somatostatin analogs, including the biased agonistic character of some agonists. The increased understanding of somatostatin receptor pharmacology provides new opportunities to design more sophisticated assays to aid the future development of somatostatin analogs with increased efficacy.
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Affiliation(s)
- Jean Claude Reubi
- Cell Biology and Experimental Cancer Research, Institute of Pathology, University of Berne, Berne, Switzerland.
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17
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Ding Y, Fan J, Li W, Yang R, Peng Y, Deng L, Wu Y, Fu Q. The effect of albumin fusion patterns on the production and bioactivity of the somatostatin-14 fusion protein in Pichia pastoris. Appl Biochem Biotechnol 2013; 170:1637-48. [PMID: 23712794 DOI: 10.1007/s12010-013-0304-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Accepted: 05/14/2013] [Indexed: 10/26/2022]
Abstract
Somatostatin is a natural inhibitor of growth hormone, and its analogues are clinically used for the therapy of acromegaly, gigantism, thyrotropinoma, and other carcinoid syndrome. However, natural somatostatin is limited for clinical usage because of its short half-life in vivo. Albumin fusion technology was used to construct long-acting fusion proteins, and Pichia pastoris was used as an expression system. Three fusion proteins, (somatostatin (SS)14)2-human serum albumin (HSA), (SS14)3-HSA, and HSA-(SS14)3, were constructed with different fusion copies of somatostatin-14 and fusion orientations. The expression level of (SS14)3-HSA and HSA-(SS14)3 was much lower than (SS14)2-HSA due to the additional fusion of the somatostatin-14 molecule. Matrix-assisted laser desorption ionization-time-of-flight mass spectrometry revealed that severe degradation occurred in the fermentation process. Similar to the standard of somatostatin-14, all three fusion proteins were able to inhibit growth hormone secretion in the blood, with (SS14)2-HSA being the most effective one. On the whole, (SS14)2-HSA was the most effective protein in both production level and bioactivity, and increasing the number of small protein copies fused to HSA may not be a suitable method to improve the protein bioactivity.
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Affiliation(s)
- Yuedi Ding
- Key Laboratory of Nuclear Medicine, Ministry of Health, Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine, QianRong Road No. 20, Wuxi, Jiangsu 214063, China
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18
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Gadelha MR, Kasuki L, Korbonits M. Novel pathway for somatostatin analogs in patients with acromegaly. Trends Endocrinol Metab 2013; 24:238-46. [PMID: 23270713 DOI: 10.1016/j.tem.2012.11.007] [Citation(s) in RCA: 105] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2012] [Revised: 11/21/2012] [Accepted: 11/24/2012] [Indexed: 01/11/2023]
Abstract
Acromegaly is a chronic disease with increased morbidity and mortality, where usually multiple treatment modalities are used. The somatostatin analogs (SSAs) are the mainstay of medical therapy but, in many patients, including those with a germline mutation in the aryl hydrocarbon receptor-interacting protein (AIP) gene, disease activity cannot be controlled with these drugs. Previous data have suggested the involvement of the tumor-suppressor gene ZAC1 in the mechanism of action of SSAs, and more recent findings suggested that SSAs could regulate AIP, which in turn can stimulate ZAC1, therefore suggesting the existence of a SSA-AIP-ZAC1-somatostatin effect pathway. The current review discusses these novel observations, highlighting their significance in the treatment of sporadic and familial somatotroph adenomas.
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Affiliation(s)
- Mônica R Gadelha
- Division of Endocrinology, Clementino Fraga Filho University Hospital, Federal University of Rio de Janeiro, Professor Rodolpho Paulo Rocco street 255, Rio de Janeiro, Brazil
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19
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Albertelli M, Arvigo M, Boschetti M, Ferone D, Gatto F, Minuto F. Somatostatin receptor pathophysiology in the neuroendocrine system. Expert Rev Endocrinol Metab 2013; 8:149-157. [PMID: 30736175 DOI: 10.1586/eem.13.7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The actions of somatostatin (SRIF) are mediated by specific G protein-coupled receptors, named SRIF receptor (SSTR) subtypes 1, 2, 3 and 5. SRIF binding to SSTR activates a series of second messenger systems, resulting in the inhibition of calcium channels and adenylate cyclase activity, ultimately leading to inhibition of hormone secretion, while stimulation of other second messengers, such as phosphotyrosine phosphatases play a role in the control of cell growth. The SSTR and dopamine receptor families share a 30% sequence homology and appear to be structurally related. The knowledge on the pathophysiology of these two families of G protein-coupled receptors in neuroendocrine tumors has progressively increased due to the new insights in receptor dimerization, internalization and trafficking. Depending on the expression of different SSTRs in tissues, their combinations and interactions affect the functionality of the subtypes expressed and the influence of the microenvironment, the response to ligands and, by consequence, the response to treatment can be very different.
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Affiliation(s)
| | - Marica Arvigo
- a Department of Internal Medicine, University of Genova, Genova, Italy
| | - Mara Boschetti
- a Department of Internal Medicine, University of Genova, Genova, Italy
- b IRCSS AOU San Martino - IST, Genova, Italy
| | - Diego Ferone
- a Department of Internal Medicine, University of Genova, Genova, Italy
- b IRCSS AOU San Martino - IST, Genova, Italy
| | - Federico Gatto
- a Department of Internal Medicine, University of Genova, Genova, Italy
| | - Francesco Minuto
- a Department of Internal Medicine, University of Genova, Genova, Italy
- b IRCSS AOU San Martino - IST, Genova, Italy
- c Department of Internal Medicine, University of Genova, Genova, Italy.
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20
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Peverelli E, Busnelli M, Vitali E, Giardino E, Galés C, Lania AG, Beck-Peccoz P, Chini B, Mantovani G, Spada A. Specific roles of G(i) protein family members revealed by dissecting SST5 coupling in human pituitary cells. J Cell Sci 2012. [PMID: 23178946 DOI: 10.1242/jcs.116434] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Despite intensive investigation over the past 20 years, the specific role played by individual G(i) protein family members in mediating complex cellular effects is still largely unclear. Therefore, we investigated the role of specific G(i) proteins in mediating somatostatin (SS) effects in somatotroph cells. Because our previous data showed that SS receptor type 5 (SST5) carrying a spontaneous R240W mutation in the third intracellular loop had a similar ability to inhibit intracellular cAMP levels to the wild-type protein but failed to mediate inhibition of growth hormone (GH) release and cell proliferation, we used this model to check specific receptor-G-protein coupling by a bioluminescent resonance energy transfer analysis. In HEK293 cells, wild-type SST5 stimulated the activation of Gα(i1-3) and Gα(oA), B, whereas R240W SST5 maintained the ability to activate Gα(i1-3) and Gα(oB), but failed to activate the splicing variant Gα(oA). To investigate the role of the selective deficit in Gα(oA) coupling, we co-transfected human adenomatous somatotrophs with SST5 and a pertussis toxin (PTX)-resistant Gα(oA) (Gα(oA(PTX-r))) protein. In PTX-treated cells, Gα(oA(PTX-r)) rescued the ability of the selective SST5 analog BIM23206 to inhibit extracellular signal-related kinase 1/2 (ERK1/2) phosphorylation, GH secretion and intracellular cAMP levels. Moreover, we demonstrated that silencing of Gα(oA) completely abolished SST5-mediated inhibitory effects on GH secretion and ERK1/2 phosphorylation, but not on cAMP levels. In conclusion, by analysing the coupling specificity of human SST5 to individual Gα(i) and Gα(o) subunits, we identified a crucial role for Gα(oA) signalling in human pituitary cells.
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Affiliation(s)
- Erika Peverelli
- Endocrinology and Diabetology Unit, Department of Clinical Sciences and Community Health, University of Milan, Fondazione IRCCS Ca' Granda Policlinico, 20122-Milan, Italy
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21
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Shpakov AO. Somatostatin receptors and signaling cascades coupled to them. J EVOL BIOCHEM PHYS+ 2012. [DOI: 10.1134/s0022093012040020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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22
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Ferone D. Italian Society of Endocrinology Career Award Lecture: from somatostatin to…somatomedin. J Endocrinol Invest 2012; 35:869-74. [PMID: 22932163 DOI: 10.3275/8583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Somatostatin plays different parts in hormonal regulation through 5 specific receptors in human body. It has two interesting actions such as an antisecretory activity, mostly on the gastrointestinal system and pituitary level, and an antiproliferative action on tumor cells. Many synthetic somatostatin analogues, more stable than the natural one, have been developed and two are already used in different clinical settings, including endocrine oncology. The inhibitory action on tumor growth may result from both indirect actions, namely the suppression of growth factors and growth-promoting hormones (e.g., GH/IGF-I axis) and inhibition of angiogenesis, as well as modulation of the immune system, and direct actions, such as activation of anti-growth activities (e.g., apoptosis). Recently, the development of specific polyclonal antibodies allowed the precise identification of the 5 specific somatostatin receptors and their localization in different cell species. Somatostatin receptor subtypes belong to the G protein-coupled receptor family, share a common molecular topology, and can traffic not only in vitro within different cell types but also in vivo. A picture of the pathways and proteins involved in these processes is beginning to emerge. Moreover, the process of homo- and/or heterodimerization of G-protein coupled receptors and receptor tyrosine kinase families are crucial for implicating the fundamental properties of receptor proteins including receptor expression, trafficking, and desensitization, as well as signal transduction. Furthermore, functional consequences of such an interaction in modulation of signaling pathways linked to pathological conditions specifically in cancer are discussed.
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Affiliation(s)
- D Ferone
- Endocrinology Unit, Department of Internal Medicine and Medical Specialties & Center of Excellence for Biomedical Research, IRCCS AOU San Martino-IST, University of Genoa, Italy.
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23
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Córdoba-Chacón J, Gahete MD, Castaño JP, Kineman RD, Luque RM. Homologous and heterologous in vitro regulation of pituitary receptors for somatostatin, growth hormone (GH)-releasing hormone, and ghrelin in a nonhuman primate (Papio anubis). Endocrinology 2012; 153:264-72. [PMID: 22109886 PMCID: PMC3249678 DOI: 10.1210/en.2011-1677] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Secretion of GH by pituitary somatotrophs is primarily stimulated by GHRH and ghrelin and inhibited by somatostatin through the activation of specific receptors [GHRH receptor (GHRH-R), GH secretagogue receptor (GHS-R) and somatostatin receptors (sst1-5), respectively]. However, we have shown that somatostatin, at low doses, can also stimulate GH release, directly and specifically, in primary pituitary cultures from a nonhuman primate (baboons, Papio anubis) and pigs. To determine whether somatostatin, GHRH, and ghrelin can also regulate the expression of their receptors in primates, pituitary cultures from baboons were treated for 4 h with GHRH or ghrelin (10(-8) m) or with high (10(-7) m) and low (10(-15) m) doses of somatostatin, and GH release and expression levels of all receptors were measured. GHRH/ghrelin decreased the expression of their respective receptors (GHRH-R and GHS-R). Both peptides increased sst1, only GHRH decreased sst5 expression, whereas sst2 expression remained unchanged. The effects of GHRH/ghrelin were completely mimicked by forskolin (adenylate cyclase activator) and phorbol 12-myristate 13-acetate (protein kinase C activator), respectively, indicating the regulation of receptor subtype levels by GHRH and ghrelin involved distinct signaling pathways. In contrast, high-dose somatostatin did not alter GH release but increased sst1, sst2, and sst5 expression, whereas GHRH-R and GHS-R expression were unaffected. Interestingly, low-dose somatostatin increased GH release and sst1 mRNA but decreased sst5 and GHRH-R expression, similar to that observed for GHRH. Altogether, our data show for the first time in a primate model that the primary regulators of somatotroph function (GHRH/ghrelin/somatostatin) exert both homologous and heterologous regulation of receptor synthesis which is dose and subtype dependent and involves distinct signaling pathways.
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MESH Headings
- Animals
- Cells, Cultured
- Colforsin/pharmacology
- Gene Expression/drug effects
- Ghrelin/administration & dosage
- Growth Hormone-Releasing Hormone/administration & dosage
- In Vitro Techniques
- Papio anubis/genetics
- Papio anubis/metabolism
- Pituitary Gland/drug effects
- Pituitary Gland/metabolism
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptors, Ghrelin/genetics
- Receptors, Ghrelin/metabolism
- Receptors, LHRH/genetics
- Receptors, LHRH/metabolism
- Receptors, Somatostatin/agonists
- Receptors, Somatostatin/genetics
- Receptors, Somatostatin/metabolism
- Signal Transduction/drug effects
- Signal Transduction/genetics
- Somatostatin/administration & dosage
- Swine
- Tetradecanoylphorbol Acetate/pharmacology
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Affiliation(s)
- Jose Córdoba-Chacón
- Department of Cell Biology, Physiology, and Immunology, University of Córdoba, E-14014 Córdoba, Spain
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Abstract
Somatostatin (SS) and dopamine (DA) receptors have been highlighted as two critical regulators in the negative control of hormonal secretion in a wide group of human endocrine tumors. Both families of receptors belong to the superfamily of G protein-coupled receptors and share a number of structural and functional characteristics. Because of the generally reported high expression of somatostatin receptors (SSTRs) in neuroendocrine tumors (NET), somatostatin analogs (SSA) have a pronounced role in the medical therapy for this class of tumors, especially pituitary adenomas and well-differentiated gastroenteropancreatic NET (GEP NET). Moreover, NET express not only SSTR but also frequently dopamine receptors (DRs), and DA agonists targeting the D(2) receptor (D(2)) have been demonstrated to be effective in controlling hormone secretion and cell proliferation in in vivo and in vitro studies. The treatment with SSAs combined with DA agonists has already been demonstrated efficacious in a subgroup of patients with GH-secreting pituitary adenomas and few reported cases of carcinoids. The recent availability of new selective and universal SSA and DA agonists, as well as the chimeric SS/DA compounds, may shed new light on the potential role of SSTR and D(2) as combined targets for biotherapy in NET. This review provides an overview of the latest studies evaluating the expression of SSTR and DR in NET, focusing on their co-expression and the possible clinical implications of such co-expression. Moreover, the most recent insights in SSTR and D(2) pathophysiology and the future perspectives for treatment with SSA, DA agonists, and SS/DA chimeric compounds are discussed.
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Affiliation(s)
- Federico Gatto
- Division of Endocrinology, Department of Internal Medicine, Erasmus Medical Center, Room Ee530b, Dr. Molewaterplein 50, 3015 GE Rotterdam, The Netherlands
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Cakir M, Dworakowska D, Grossman A. Somatostatin receptor biology in neuroendocrine and pituitary tumours: part 1--molecular pathways. J Cell Mol Med 2011; 14:2570-84. [PMID: 20629989 PMCID: PMC4373477 DOI: 10.1111/j.1582-4934.2010.01125.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Neuroendocrine tumours (NETs) may occur at many sites in the body although the majority occur within the gastroenteropancreatic axis. Non-gastroenteropancreatic NETs encompass phaeochromocytomas and paragangliomas, medullary thyroid carcinoma, anterior pituitary tumour, broncho-pulmonary NETs and parathyroid tumours. Like most endocrine tumours, NETs also express somatostatin (SST) receptors (subtypes 1–5) whose ligand SST is known to inhibit endocrine and exocrine secretions and have anti-tumour effects. In the light of this knowledge, the idea of using SST analogues in the treatment of NETs has become increasingly popular and new studies have centred upon the development of new SST analogues. We attempt to review SST receptor (SSTR) biology primarily in neuroendocrine tissues, focusing on pituitary tumours. A full data search was performed through PubMed over the years 2000–2009 with keywords ‘somatostatin, molecular biology, somatostatin receptors, somatostatin signalling, NET, pituitary’ and all relevant publications have been included, together with selected publications prior to that date. SSTR signalling in non-neuroendocrine solid tumours is beyond the scope of this review. SST is a potent anti-proliferative and anti-secretory agent for some NETs. The successful therapeutic use of SST analogues in the treatment of these tumours depends on a thorough understanding of the diverse effects of SSTR subtypes in different tissues and cell types. Further studies will focus on critical points of SSTR biology such as homo- and heterodimerization of SSTRs and the differences between post-receptor signalling pathways of SSTR subtypes.
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Affiliation(s)
- Mehtap Cakir
- Selcuk University, Meram School of Medicine, Division of Endocrinology and Metabolism, Konya, Turkey.
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Kao YJ, Ghosh M, Schonbrunn A. Ligand-dependent mechanisms of sst2A receptor trafficking: role of site-specific phosphorylation and receptor activation in the actions of biased somatostatin agonists. Mol Endocrinol 2011; 25:1040-54. [PMID: 21493671 DOI: 10.1210/me.2010-0398] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The somatostatin receptor subtype 2A (sst2A) mediates many of somatostatin's neuroendocrine actions and is the primary therapeutic target for the stable somatostatin analogs used to inhibit hormone secretion by pituitary and gastroenteropancreatic tumors. Two new multireceptor targeting somatostatin analogs currently under clinical investigation, the multisomatostatin receptor agonist cyclo-[diaminoethylcarbamoyl-HydroxyPro-Phenylglycine-D-Trp-Lys-(4-O-benzyl)Tyr-Phe] (SOM230) (Pasireotide) and pan-somatostatin receptor agonist Tyr-cyclo-[D-diaminobutyric acid-Arg-Phe-Phe-D-Trp-Lys-Thr-Phe] (KE108), behave as functionally selective ligands at the sst2A receptor, mimicking some of somatostatin's actions but antagonizing others. Further, SOM230 and KE108 are less able to induce receptor internalization than somatostatin, indicating that they exhibit functional selectivity for receptor regulation as well as signaling. Here, we identify agonist-specific differences in the molecular events regulating sst2A receptor endocytosis. SOM230 and KE108 were less potent and less effective than somatostatin at stimulating sst2A receptor phosphorylation at two pairs of residues, Ser341/343 and Thr353/354. Only the pattern of Thr353/354 phosphorylation correlated with receptor internalization, consistent with the known importance of Thr phosphorylation for sst2A receptor endocytosis. As expected, arrestin recruitment to membrane receptors was reduced with SOM230 and KE108. In addition, both receptor dephosphorylation and receptor recycling occurred more rapidly with SOM230 and KE108 than with somatostatin. Surprisingly, however, SOM230 and KE108 also altered sst2A internalization in a phosphorylation-independent manner, because these analogs were less effective than somatostatin at stimulating the endocytosis of a phosphorylation-negative receptor mutant. These results show that the decreased receptor internalization produced by SOM230 and KE108 compared with somatostatin result from phosphorylation-independent effects as well as reduced site-specific receptor phosphorylation and receptor-arrestin association.
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Affiliation(s)
- Yachu J Kao
- Department of Integrative Biology and Pharmacology, University of Texas, Health Science Center-Houston, Houston, Texas 77030, USA
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Breit A, Büch TRH, Boekhoff I, Solinski HJ, Damm E, Gudermann T. Alternative G protein coupling and biased agonism: new insights into melanocortin-4 receptor signalling. Mol Cell Endocrinol 2011; 331:232-40. [PMID: 20674667 DOI: 10.1016/j.mce.2010.07.007] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2010] [Revised: 05/06/2010] [Accepted: 07/13/2010] [Indexed: 11/20/2022]
Abstract
The melanocortin-4 receptor (MC4R) is a prototypical G protein-coupled receptor (GPCR) that plays a considerable role in controlling appetite and energy homeostasis. Signalling initiated by MC4R is orchestrated by multiple agonists, inverse agonism and by interactions with accessory proteins. The exact molecular events translating MC4R signalling into its physiological role, however, are not fully understood. This review is an attempt to summarize new aspects of MC4R signalling in the context of its recently discovered alternative G protein coupling, and to give a perspective on how future research could improve our knowledge about the intertwining molecular mechanisms that are responsible for the regulation of energy homeostasis by the melanocortin system.
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Affiliation(s)
- Andreas Breit
- Walther-Straub-Institut für Pharmakologie und Toxikologie, Goethestrasse 33, Ludwig-Maximilians-Universität München, 80336 München, Germany.
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Cakir M, Dworakowska D, Grossman A. Somatostatin receptor biology in neuroendocrine and pituitary tumours: part 2--clinical implications. J Cell Mol Med 2010; 14:2585-91. [PMID: 20629988 PMCID: PMC4373478 DOI: 10.1111/j.1582-4934.2010.01125_1.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2010] [Accepted: 04/29/2010] [Indexed: 01/03/2023] Open
Abstract
Introduction
SSTR subtype tissue distribution and its relevance to tumour imaging and treatment
Conclusions
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Affiliation(s)
- Mehtap Cakir
- Selcuk University, Meram School of Medicine, Division of Endocrinology and Metabolism, Konya, Turkey.
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Arnaldi G, Boscaro M. Pasireotide for the treatment of Cushing's disease. Expert Opin Investig Drugs 2010; 19:889-98. [DOI: 10.1517/13543784.2010.495943] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Ovadia O, Greenberg S, Laufer B, Gilon C, Hoffman A, Kessler H. Improvement of drug-like properties of peptides: the somatostatin paradigm. Expert Opin Drug Discov 2010; 5:655-71. [DOI: 10.1517/17460441.2010.493935] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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van der Hoek J, Lamberts SWJ, Hofland LJ. The somatostatin receptor subtype 5 in neuroendocrine tumours. Expert Opin Investig Drugs 2010; 19:385-99. [PMID: 20151855 DOI: 10.1517/13543781003604710] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
IMPORTANCE OF THE FIELD In recent years, scientific work has been intensified to unravel new (patho-) physiological insights, particularly regarding the functional role of somatostatin (SRIF) receptor subtype 5 (sst) and the development of novel sst(5)-targeted SRIF analogues, in order to broaden medical therapeutic opportunities in patients suffering from neuroendocrine diseases. AREAS COVERED IN THIS REVIEW The scope of this review is primarily focused upon recent insights in sst(5)-receptor physiology, novel sst(5)-targeted treatment options predominantly directed towards pituitary adenomas, and gastroenteropancreatic neuroendocrine tumours. WHAT THE READER WILL GAIN An understanding of the potential that novel sst(5)-targeted SRIF analogues might have in the medical treatment of Cushing's disease and acromegaly, as demonstrated by translational research, based on pathophysiological data combined with results from clinical trials. TAKE HOME MESSAGE The role of targeting sst(5) in gastroenteropancreatic neuroendocrine tumours remains to be established. The sst(5) subtype might function as sst(2) modulator in terms of receptor internalization and desensitization, and seems less important compared with sst(2)-preferring SRIF analogues in the regulation of human insulin secretion by the pancreas. Finally, absence of sst(5) in corticotroph adenomas could be related to tumour aggressiveness in Cushing's disease.
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Affiliation(s)
- Joost van der Hoek
- Department of Internal Medicine, Division of Endocrinology, Room Ee530b, Erasmus MC, Dr Molewaterplein 50, 3015 GE Rotterdam, The Netherlands.
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Córdoba-Chacón J, Gahete MD, Duran-Prado M, Pozo-Salas AI, Malagón MM, Gracia-Navarro F, Kineman RD, Luque RM, Castaño JP. Identification and characterization of new functional truncated variants of somatostatin receptor subtype 5 in rodents. Cell Mol Life Sci 2010; 67:1147-63. [PMID: 20063038 PMCID: PMC11115927 DOI: 10.1007/s00018-009-0240-y] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2009] [Revised: 12/08/2009] [Accepted: 12/18/2009] [Indexed: 12/11/2022]
Abstract
Somatostatin and cortistatin exert multiple biological actions through five receptors (sst1-5); however, not all their effects can be explained by activation of sst1-5. Indeed, we recently identified novel truncated but functional human sst5-variants, present in normal and tumoral tissues. In this study, we identified and characterized three novel truncated sst5 variants in mice and one in rats displaying different numbers of transmembrane-domains [TMD; sst5TMD4, sst5TMD2, sst5TMD1 (mouse-variants) and sst5TMD1 (rat-variant)]. These sst5 variants: (1) are functional to mediate ligand-selective-induced variations in [Ca(2+)]i and cAMP despite being truncated; (2) display preferential intracellular distribution; (3) mostly share full-length sst5 tissue distribution, but exhibit unique differences; (4) are differentially regulated by changes in hormonal/metabolic environment in a tissue- (e.g., central vs. systemic) and ligand-dependent manner. Altogether, our results demonstrate the existence of new truncated sst5-variants with unique ligand-selective signaling properties, which could contribute to further understanding the complex, distinct pathophysiological roles of somatostatin and cortistatin.
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Affiliation(s)
- Jose Córdoba-Chacón
- Department of Cell Biology, Physiology and Immunology, University of Córdoba, Edificio Severo Ochoa. Planta 3. Campus de Rabanales, 14014 Córdoba, Spain
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Córdoba, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn 06/03), Córdoba, Spain
| | - Manuel D. Gahete
- Department of Cell Biology, Physiology and Immunology, University of Córdoba, Edificio Severo Ochoa. Planta 3. Campus de Rabanales, 14014 Córdoba, Spain
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Córdoba, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn 06/03), Córdoba, Spain
| | - Mario Duran-Prado
- Department of Cell Biology, Physiology and Immunology, University of Córdoba, Edificio Severo Ochoa. Planta 3. Campus de Rabanales, 14014 Córdoba, Spain
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Córdoba, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn 06/03), Córdoba, Spain
| | - Ana I. Pozo-Salas
- Department of Cell Biology, Physiology and Immunology, University of Córdoba, Edificio Severo Ochoa. Planta 3. Campus de Rabanales, 14014 Córdoba, Spain
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Córdoba, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn 06/03), Córdoba, Spain
| | - María M. Malagón
- Department of Cell Biology, Physiology and Immunology, University of Córdoba, Edificio Severo Ochoa. Planta 3. Campus de Rabanales, 14014 Córdoba, Spain
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Córdoba, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn 06/03), Córdoba, Spain
| | - F. Gracia-Navarro
- Department of Cell Biology, Physiology and Immunology, University of Córdoba, Edificio Severo Ochoa. Planta 3. Campus de Rabanales, 14014 Córdoba, Spain
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Córdoba, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn 06/03), Córdoba, Spain
| | - Rhonda D. Kineman
- Research and Development Division, Jesse Brown Veterans Affairs Medical Center, Chicago, IL USA
- Section of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Illinois at Chicago, Chicago, IL USA
| | - Raul M. Luque
- Department of Cell Biology, Physiology and Immunology, University of Córdoba, Edificio Severo Ochoa. Planta 3. Campus de Rabanales, 14014 Córdoba, Spain
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Córdoba, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn 06/03), Córdoba, Spain
| | - Justo P. Castaño
- Department of Cell Biology, Physiology and Immunology, University of Córdoba, Edificio Severo Ochoa. Planta 3. Campus de Rabanales, 14014 Córdoba, Spain
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Córdoba, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn 06/03), Córdoba, Spain
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Martino MCD, Hofland LJ, Lamberts SW. Somatostatin and Somatostatin Receptors: from Basic Concepts to Clinical Applications. PROGRESS IN BRAIN RESEARCH 2010; 182:255-80. [DOI: 10.1016/s0079-6123(10)82011-4] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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The gastrointestinal tract as an endocrine/neuroendocrine/paracrine organ: organization, chemical messengers and physiological targets. FISH PHYSIOLOGY 2010. [DOI: 10.1016/s1546-5098(10)03007-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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Cescato R, Loesch KA, Waser B, Mäcke HR, Rivier JE, Reubi JC, Schonbrunn A. Agonist-biased signaling at the sst2A receptor: the multi-somatostatin analogs KE108 and SOM230 activate and antagonize distinct signaling pathways. Mol Endocrinol 2009; 24:240-9. [PMID: 19910453 DOI: 10.1210/me.2009-0321] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Somatostatin analogs that activate the somatostatin subtype 2A (sst2A) receptor are used to treat neuroendocrine cancers because they inhibit tumor secretion and growth. Recently, new analogs capable of activating multiple somatostatin receptor subtypes have been developed to increase tumor responsiveness. We tested two such multi-somatostatin analogs for functional selectivity at the sst2A receptor: SOM230, which activates sst1, sst2, sst3, and sst5 receptors, and KE108, which activates all sst receptor subtypes. Both compounds are reported to act as full agonists at their target sst receptors. In sst2A-expressing HEK293 cells, somatostatin inhibited cAMP production, stimulated intracellular calcium accumulation, and increased ERK phosphorylation. SOM230 and KE108 were also potent inhibitors of cAMP accumulation, as expected. However, they antagonized somatostatin stimulation of intracellular calcium and behaved as partial agonists/antagonists for ERK phosphorylation. In pancreatic AR42J cells, which express sst2A receptors endogenously, SOM230 and KE108 were both full agonists for cAMP inhibition. However, although somatostatin increased intracellular calcium and ERK phosphorylation, SOM230 and KE108 again antagonized these effects. Distinct mechanisms were involved in sst2A receptor signaling in AR42J cells; pertussis toxin pretreatment blocked somatostatin inhibition of cAMP accumulation but not the stimulation of intracellular calcium and ERK phosphorylation. Our results demonstrate that SOM230 and KE108 behave as agonists for inhibition of adenylyl cyclase but antagonize somatostatin's actions on intracellular calcium and ERK phosphorylation. Thus, SOM230 and KE108 are not somatostatin mimics, and their functional selectivity at sst2A receptors must be considered in clinical applications where it may have important consequences for therapy.
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Affiliation(s)
- Renzo Cescato
- Division of Cell Biology, Institute of Pathology, University of Berne, Berne, Switzerland
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Büch TRH, Heling D, Damm E, Gudermann T, Breit A. Pertussis toxin-sensitive signaling of melanocortin-4 receptors in hypothalamic GT1-7 cells defines agouti-related protein as a biased agonist. J Biol Chem 2009; 284:26411-20. [PMID: 19648111 DOI: 10.1074/jbc.m109.039339] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Melanocortin-4 receptor (MC4R)-induced anorexigenic signaling in the hypothalamus controls body weight and energy homeostasis. So far, MC4R-induced signaling has been exclusively attributed to its coupling to G(s) proteins. In line with this monogamous G protein coupling profile, most MC4R mutants isolated from obese individuals showed a reduced ability to activate G(s). However, some mutants displayed enhanced G(s) coupling, suggesting that signaling pathways independent of G(s) may be involved in MC4R-mediated anorexigenic signaling. Here we report that the G(s) signaling-deficient MC4R-D90N mutant activates G proteins in a pertussis toxin-sensitive manner, indicating that this mutant is able to selectively interact with G(i/o) proteins. Analyzing a hypothalamic cell line (GT1-7 cells), we observed activation of pertussis toxin-sensitive G proteins by the wild-type MC4R as well, reflecting multiple coupling of the MC4R to G(s) and G(i/o) proteins in an endogenous cell system. Surprisingly, the agouti-related protein, which has been classified as a MC4R antagonist, selectively activates G(i/o) signaling in GT1-7 cells. Thus, the agouti-related protein antagonizes melanocortin-dependent G(s) activation not only by competitive antagonism but additionally by initiating G(i/o) protein-induced signaling as a biased agonist.
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Affiliation(s)
- Thomas R H Büch
- Walther-Straub-Institut für Pharmakologie und Toxikologie, Ludwig-Maximilians-Universität München, 80336 München
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Van Op den Bosch J, Adriaensen D, Van Nassauw L, Timmermans JP. The role(s) of somatostatin, structurally related peptides and somatostatin receptors in the gastrointestinal tract: a review. ACTA ACUST UNITED AC 2009; 156:1-8. [PMID: 19362110 DOI: 10.1016/j.regpep.2009.04.003] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2009] [Accepted: 04/05/2009] [Indexed: 12/19/2022]
Abstract
Extensive functional and morphological research has demonstrated the pivotal role of somatostatin (SOM) in the regulation of a wide variety of gastrointestinal activities. In addition to its profound inhibitory effects on gastrointestinal motility and exocrine and endocrine secretion processes along the entire gastrointestinal tract, SOM modulates several organ-specific activities. In contrast to these well-known SOM-dependent effects, knowledge on the SOM receptors (SSTR) involved in these effects is much less conclusive. Experimental data on the identities of the SSTRs, although species- and tissue-dependent, point towards the involvement of multiple receptor subtypes in the vast majority of gastrointestinal SOM-mediated effects. Recent evidence demonstrating the role of SOM in intestinal pathologies has extended the interest of gastrointestinal research in this peptide even further. More specifically, SOM is supposed to suppress intestinal inflammatory responses by interfering with the extensive bidirectional communication between mucosal mast cells and neurons. This way, SOM not only acts as a powerful inhibitor of the inflammatory cascade at the site of inflammation, but exerts a profound antinociceptive effect through the modulation of extrinsic afferent nerve fibres. The combination of these physiological and pathological activities opens up new opportunities to explore the potential of stable SOM analogues in the treatment of GI inflammatory pathologies.
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Affiliation(s)
- Joeri Van Op den Bosch
- Laboratory of Cell Biology & Histology, Department of Veterinary Sciences, University of Antwerp, Antwerp, Belgium
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Aplin M, Bonde MM, Hansen JL. Molecular determinants of angiotensin II type 1 receptor functional selectivity. J Mol Cell Cardiol 2009; 46:15-24. [DOI: 10.1016/j.yjmcc.2008.09.123] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2008] [Revised: 09/09/2008] [Accepted: 09/18/2008] [Indexed: 01/14/2023]
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Hoffmann C, Ziegler N, Reiner S, Krasel C, Lohse MJ. Agonist-selective, receptor-specific interaction of human P2Y receptors with beta-arrestin-1 and -2. J Biol Chem 2008; 283:30933-41. [PMID: 18703513 DOI: 10.1074/jbc.m801472200] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Interaction of G-protein-coupled receptors with beta-arrestins is an important step in receptor desensitization and in triggering "alternative" signals. By means of confocal microscopy and fluorescence resonance energy transfer, we have investigated the internalization of the human P2Y receptors 1, 2, 4, 6, 11, and 12 and their interaction with beta-arrestin-1 and -2. Co-transfection of each individual P2Y receptor with beta-arrestin-1-GFP or beta-arrestin-2-YFP into HEK-293 cells and stimulation with the corresponding agonists resulted in a receptor-specific interaction pattern. The P2Y(1) receptor stimulated with ADP strongly translocated beta-arrestin-2-YFP, whereas only a slight translocation was observed for beta-arrestin-1-GFP. The P2Y(4) receptor exhibited equally strong translocation for beta-arrestin-1-GFP and beta-arrestin-2-YFP when stimulated with UTP. The P2Y(6), P2Y(11), and P2Y(12) receptor internalized only when GRK2 was additionally co-transfected, but beta-arrestin translocation was only visible for the P2Y(6) and P2Y(11) receptor. The P2Y(2) receptor showed a beta-arrestin translocation pattern that was dependent on the agonist used for stimulation. UTP translocated beta-arrestin-1-GFP and beta-arrestin-2-YFP equally well, whereas ATP translocated beta-arrestin-1-GFP to a much lower extent than beta-arrestin-2-YFP. The same agonist-dependent pattern was seen in fluorescence resonance energy transfer experiments between the fluorescently labeled P2Y(2) receptor and beta-arrestins. Thus, the P2Y(2) receptor would be classified as a class A receptor when stimulated with ATP or as a class B receptor when stimulated with UTP. The ligand-specific recruitment of beta-arrestins by ATP and UTP stimulation of P2Y(2) receptors was further found to result in differential stimulation of ERK phosphorylation. This suggests that the two different agonists induce distinct active states of this receptor that show differential interactions with beta-arrestins.
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Affiliation(s)
- Carsten Hoffmann
- Institute for Pharmacology and Toxicology, Versbacher Strasse 9, D-97078 Wuerzburg, Germany.
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40
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Durán-Prado M, Malagón MM, Gracia-Navarro F, Castaño JP. Dimerization of G protein-coupled receptors: new avenues for somatostatin receptor signalling, control and functioning. Mol Cell Endocrinol 2008; 286:63-8. [PMID: 18242821 DOI: 10.1016/j.mce.2007.12.006] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2007] [Accepted: 12/11/2007] [Indexed: 12/24/2022]
Abstract
Somatostatin acts through binding and activation of five G protein-coupled receptors (GPCRs) termed somatostatin receptors or ssts (sst1-sst5). These receptors, as many other GPCRs are not just monomers but display a differential tendency to homodimerize, which varies depending on the sst subtype. Moreover, there is evidence that pairs of distinct receptors such as ssst2-sst3 and sst1-sst5 crosstalk by establishing a physical interaction, which results in altered pharmacological or/and functional properties. In addition, ssts can also heterodimerize with other families of GPCRs, as opioid and dopamine receptors, originating heterodimers which properties are different to those of their separated receptors. The present review summarizes the current knowledge on ssts homodimerization, heterodimerization, and interaction with other GPCRs, as well as how interactions affect different aspects of the normal functioning of these receptors.
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Affiliation(s)
- Mario Durán-Prado
- Department of Cell Biology, Physiology and Immunology, University of Córdoba, Córdoba, Spain
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