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Spada A, Mantovani G, Lania AG, Treppiedi D, Mangili F, Catalano R, Carosi G, Sala E, Peverelli E. Pituitary Tumors: Genetic and Molecular Factors Underlying Pathogenesis and Clinical Behavior. Neuroendocrinology 2022; 112:15-33. [PMID: 33524974 DOI: 10.1159/000514862] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2020] [Accepted: 02/01/2021] [Indexed: 11/19/2022]
Abstract
Pituitary neuroendocrine tumors (PitNETs) are the most common intracranial neoplasms. Although generally benign, they can show a clinically aggressive course, with local invasion, recurrences, and resistance to medical treatment. No universally accepted biomarkers of aggressiveness are available yet, and predicting clinical behavior of PitNETs remains a challenge. In rare cases, the presence of germline mutations in specific genes predisposes to PitNET formation, as part of syndromic diseases or familial isolated pituitary adenomas, and associates to more aggressive, invasive, and drug-resistant tumors. The vast majority of cases is represented by sporadic PitNETs. Somatic mutations in the α subunit of the stimulatory G protein gene (gsp) and in the ubiquitin-specific protease 8 (USP8) gene have been recognized as pathogenetic factors in sporadic GH- and ACTH-secreting PitNETs, respectively, without an association with a worse clinical phenotype. Other molecular factors have been found to significantly affect PitNET drug responsiveness and invasive behavior. These molecules are cytoskeleton and/or scaffold proteins whose alterations prevent proper functioning of the somatostatin and dopamine receptors, targets of medical therapy, or promote the ability of tumor cells to invade surrounding tissues. The aim of the present review is to provide an overview of the genetic and molecular alterations that can contribute to determine PitNET clinical behavior. Understanding subcellular mechanisms underlying pituitary tumorigenesis and PitNET clinical phenotype will hopefully lead to identification of new potential therapeutic targets and new markers predicting the behavior and the response to therapeutic treatments of PitNETs.
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Affiliation(s)
- Anna Spada
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Giovanna Mantovani
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
- Endocrinology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Andrea G Lania
- Endocrinology, Diabetology and Medical Andrology Unit, Humanitas Clinical and Research Center, IRCCS, Milan, Italy
- Department of Biomedical Sciences, Humanitas University, Milan, Italy
| | - Donatella Treppiedi
- 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
| | - Rosa Catalano
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Giulia Carosi
- Endocrinology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Elisa Sala
- Endocrinology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Erika Peverelli
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy,
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Egal ESA, Jacenik D, Soares HP, Beswick EJ. Translational challenges in pancreatic neuroendocrine tumor immunotherapy. Biochim Biophys Acta Rev Cancer 2021; 1876:188640. [PMID: 34695532 PMCID: PMC10695297 DOI: 10.1016/j.bbcan.2021.188640] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 09/19/2021] [Accepted: 10/18/2021] [Indexed: 12/28/2022]
Abstract
Pancreatic neuroendocrine tumors are rare types of pancreatic cancer formed from islet cells of pancreas. Clinical presentation of pancreatic neuroendocrine tumors depends on both tumor progression and hormone secretion status, which generate several complications in both diagnosis and treatment. Despite numerous strategies, treatment of patients with pancreatic neuroendocrine tumors still needs improvement. It is suggested that immune response modulation may be essential in the regulation of pancreatic neuroendocrine tumor progression and patient's symptomology. Accumulating evidence indicates that immunotherapy seems to be a promising treatment option for patients with pancreatic neuroendocrine tumors. Nevertheless, several challenges in pre-clinical and clinical studies are present. This review provides knowledge about microenvironment of pancreatic neuroendocrine tumors including significance of cytokine and chemokine as well as specific immune cell types. Additionally, in vitro and in vivo models of pancreatic neuroendocrine tumors and translational challenges are highlighted.
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Affiliation(s)
- Erika Said Abu Egal
- Division of Gastroenterology, Department of Internal Medicine, University of Utah, UT, Salt Lake City, United States
| | - Damian Jacenik
- Division of Gastroenterology, Department of Internal Medicine, University of Utah, UT, Salt Lake City, United States; Division of Oncology, Department of Internal Medicine, Huntsman Cancer Institute at the University of Utah, UT, Salt Lake City, United States; Department of Cytobiochemistry, Faculty of Biology and Environmental Protection, University of Lodz, Lodz, Poland
| | - Heloisa Prado Soares
- Division of Oncology, Department of Internal Medicine, Huntsman Cancer Institute at the University of Utah, UT, Salt Lake City, United States.
| | - Ellen J Beswick
- Division of Gastroenterology, Department of Internal Medicine, University of Utah, UT, Salt Lake City, United States
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Peverelli E, Treppiedi D, Mangili F, Catalano R, Spada A, Mantovani G. Drug resistance in pituitary tumours: from cell membrane to intracellular signalling. Nat Rev Endocrinol 2021; 17:560-571. [PMID: 34194011 DOI: 10.1038/s41574-021-00514-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/19/2021] [Indexed: 02/06/2023]
Abstract
The pharmacological treatment of pituitary tumours is based on the use of stable analogues of somatostatin and dopamine. The analogues bind to somatostatin receptor types 2 and 5 (SST2 and SST5) and dopamine receptor type 2 (DRD2), respectively, and generate signal transduction cascades in cancerous pituitary cells that culminate in the inhibition of hormone secretion, cell growth and invasion. Drug resistance occurs in a subset of patients and can involve different steps at different stages, such as following receptor activation by the agonist or during the final biological responses. Although the expression of somatostatin and dopamine receptors in cancer cells is a prerequisite for these drugs to reach a biological effect, their presence does not guarantee the success of the therapy. Successful therapy also requires the proper functioning of the machinery of signal transduction and the finely tuned regulation of receptor desensitization, internalization and intracellular trafficking. The present Review provides an updated overview of the molecular factors underlying the pharmacological resistance of pituitary tumours. The Review discusses the experimental evidence that supports a role for receptors and intracellular proteins in the function of SSTs and DRD2 and their clinical importance.
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Affiliation(s)
- Erika Peverelli
- University of Milan, Department of Clinical Sciences and Community Health, Milan, Italy.
| | - Donatella Treppiedi
- University of Milan, Department of Clinical Sciences and Community Health, Milan, Italy
| | - Federica Mangili
- University of Milan, Department of Clinical Sciences and Community Health, Milan, Italy
| | - Rosa Catalano
- University of Milan, Department of Clinical Sciences and Community Health, Milan, Italy
- PhD Program in Endocrinological Sciences, Sapienza University of Rome, Rome, Italy
| | - Anna Spada
- University of Milan, Department of Clinical Sciences and Community Health, Milan, Italy
| | - Giovanna Mantovani
- University of Milan, Department of Clinical Sciences and Community Health, Milan, Italy
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Endocrinology Unit, Milan, Italy
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Vitali E, Piccini S, Trivellin G, Smiroldo V, Lavezzi E, Zerbi A, Pepe G, Lania AG. The impact of SST2 trafficking and signaling in the treatment of pancreatic neuroendocrine tumors. Mol Cell Endocrinol 2021; 527:111226. [PMID: 33675866 DOI: 10.1016/j.mce.2021.111226] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 02/17/2021] [Accepted: 02/21/2021] [Indexed: 01/01/2023]
Abstract
Pancreatic neuroendocrine tumors (Pan-NETs), are heterogeneous neoplasms, whose incidence and prevalence are increasing worldwide. Pan-NETs are characterized by the expression of somatostatin receptors (SSTs). In particular, SST2 is the most widely distributed SST in NETs, thus representing the main molecular target for somatostatin analogs (SSAs). SSAs are currently approved for the treatment of well-differentiated NETs, and radionuclide-labeled SSAs are used for diagnostic and treatment purposes. SSAs, by binding to SSTs, have been shown to inhibit hormone secretion and thus provide control of hypersecretion symptoms, when present, and inhibit tumor proliferation. After SSA binding to SST2, the fate of the receptor is determined by trafficking mechanisms, crucial for the response to endogenous or pharmacological ligands. Although SST2 acts mostly through G protein-dependent mechanism, receptor-ligand complex endocytosis and receptor trafficking further regulate its function. SST2 mediates the decrease of hormone secretion via a G protein-dependent mechanism, culminating with the inhibition of adenylyl cyclase and calcium channels; it also inhibits cell proliferation and increases apoptosis through the modulation of protein tyrosine phosphatases. Moreover, SST2 inhibits angiogenesis and cell migration. In this respect, the cross-talk between SST2 and its interacting proteins, including Filamin A (FLNA) and aryl hydrocarbon receptor-interacting protein (AIP), plays a crucial role for SST2 signaling and responsiveness to SSAs. This review will focus on recent studies from our and other groups that have investigated the trafficking and signaling of SST2 in Pan-NETs, in order to provide insights into the mechanisms underlying tumor responsiveness to pharmacological treatments.
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Affiliation(s)
- E Vitali
- Laboratory of Cellular and Molecular Endocrinology, Italy; Department of Biomedical Sciences, Humanitas University, Rozzano, Italy.
| | - S Piccini
- Laboratory of Cellular and Molecular Endocrinology, Italy; Department of Biomedical Sciences, Humanitas University, Rozzano, Italy
| | - G Trivellin
- Laboratory of Cellular and Molecular Endocrinology, Italy; Laboratory of Pharmacology and Brain Pathology, Humanitas Clinical and Research Center - IRCCS, Rozzano, Italy
| | - V Smiroldo
- Oncology Unit, Humanitas Clinical and Research Center - IRCCS, Rozzano, Italy
| | - E Lavezzi
- Endocrinology and Diabetology Unit Humanitas Clinical and Research Center - IRCCS, Rozzano, Italy
| | - A Zerbi
- Department of Biomedical Sciences, Humanitas University, Rozzano, Italy; Pancreas Surgery Unit, Humanitas Clinical and Research Center - IRCCS, Rozzano, Italy
| | - G Pepe
- Nuclear Medicine Humanitas Clinical and Research Center - IRCCS, Rozzano, Italy
| | - A G Lania
- Laboratory of Cellular and Molecular Endocrinology, Italy; Department of Biomedical Sciences, Humanitas University, Rozzano, Italy; Endocrinology and Diabetology Unit Humanitas Clinical and Research Center - IRCCS, Rozzano, Italy
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Haider M, Das S, Al-Toubah T, Pelle E, El-Haddad G, Strosberg J. Somatostatin receptor radionuclide therapy in neuroendocrine tumors. Endocr Relat Cancer 2021; 28:R81-R93. [PMID: 33608483 PMCID: PMC8118168 DOI: 10.1530/erc-20-0360] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 02/10/2021] [Indexed: 12/28/2022]
Abstract
Peptide receptor radionuclide therapy (PRRT) using 177Lu-DOTATATE has been approved for the treatment of gastroenteropancreatic NETs. An understanding of benefits and risks is important for the appropriate implementation of this therapy. This review summarizes study data supporting the use of radiolabeled somatostatin analogs for the treatment of advanced NETs and highlights risks, including potential toxicities in specific populations. Key ongoing clinical trials, including randomized studies, are designed to better define the position of PRRT within the broader therapeutic landscape. Preclinical and early-phase human studies are focused on the development of novel somatostatin-receptor agonists and antagonists, new radionuclides, and radiosensitizing combination therapies.
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Affiliation(s)
- Mintallah Haider
- Moffitt Cancer Center, Department of GI Oncology, Tampa, Florida, USA
| | - Satya Das
- Department of GI Oncology, Vanderbilt University, Nashville, Tennessee, USA
| | | | - Eleonora Pelle
- Department of Oncology, University of Bari, Bari, Puglia, Italy
| | - Ghassan El-Haddad
- Moffitt Cancer Center, Department of Diagnostic Imaging and Interventional Radiology, Tampa, Florida, USA
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Mangili F, Giardino E, Treppiedi D, Barbieri AM, Catalano R, Locatelli M, Lania AG, Spada A, Arosio M, Mantovani G, Peverelli E. Beta-Arrestin 2 Is Required for Dopamine Receptor Type 2 Inhibitory Effects on AKT Phosphorylation and Cell Proliferation in Pituitary Tumors. Neuroendocrinology 2021; 111:568-579. [PMID: 32512568 DOI: 10.1159/000509219] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 06/08/2020] [Indexed: 11/19/2022]
Abstract
Dopamine receptor type 2 (DRD2) agonists are the first-choice treatment for prolactin-secreting pituitary tumors but are poorly effective in nonfunctioning pituitary neuroendocrine tumors (NF-PitNETs). DRD2 reduces AKT phosphorylation in lactotrophs, but no data are available in NF-PitNETs. DRD2 effects on AKT are mediated by a β-arrestin 2-dependent mechanism in mouse striatum. The aim of this study was to investigate DRD2 effects on AKT phosphorylation and cell proliferation in human primary cultured NF-PitNET cells and in rat tumoral lactotroph cells MMQ, and to test β-arrestin 2 involvement. We found that the DRD2 agonist BIM53097 induced a reduction of the p-AKT/total-AKT ratio in MMQ (-32.8 ± 17.6%, p < 0.001 vs. basal) and in a subset (n = 15/41, 36.6%) of NF-PitNETs (subgroup 1). In the remaining NF-PitNETs (subgroup 2), BIM53097 induced an increase in p-AKT. The ability of BIM53097 to reduce p-AKT correlated with its antimitotic effect, since the majority of subgroup 1 NF-PitNETs was responsive to BIM53097, and nearly all subgroup 2 NF-PitNETs were resistant. β-Arrestin 2 was expressed in MMQ and in 80% of subgroup 1 NF-PitNETs, whereas it was undetectable in 77% of subgroup 2 NF-PitNETs. In MMQ, β-arrestin 2 silencing prevented DRD2 inhibitory effects on p-AKT and cell proliferation. Accordingly, β-arrestin 2 transfection in subgroup 2 NF-PitNETs conferred to BIM53097 the ability to inhibit both p-AKT and cell growth. In conclusion, we demonstrated that β-arrestin 2 is required for DRD2 inhibitory effects on AKT phosphorylation and cell proliferation in MMQ and NF-PitNETs, paving the way for a potential role of β-arrestin 2 as a biomarker predicting NF-PitNETs' responsiveness to treatment with dopamine agonists.
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Affiliation(s)
- Federica Mangili
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Elena Giardino
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Donatella Treppiedi
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Anna Maria Barbieri
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Rosa Catalano
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
- PhD Program in Endocrinological Science, Sapienza University of Rome, Rome, Italy
| | - Marco Locatelli
- Neurosurgery Unit, Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico, Milan, Italy
- Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
| | - Andrea Gerardo Lania
- Endocrine Unit, IRCCS Humanitas Clinical Institute, Humanitas University, Rozzano, Italy
| | - Anna Spada
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Maura Arosio
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
- Endocrinology Unit, Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Giovanna Mantovani
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy,
- Endocrinology Unit, Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico, Milan, Italy,
| | - Erika Peverelli
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
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Treppiedi D, Mangili F, Giardino E, Catalano R, Locatelli M, Lania AG, Spada A, Arosio M, Calebiro D, Mantovani G, Peverelli E. Cytoskeleton Protein Filamin A Is Required for Efficient Somatostatin Receptor Type 2 Internalization and Recycling through Rab5 and Rab4 Sorting Endosomes in Tumor Somatotroph Cells. Neuroendocrinology 2020; 110:642-652. [PMID: 31574507 DOI: 10.1159/000503791] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 09/30/2019] [Indexed: 11/19/2022]
Abstract
The high expression of somatostatin receptor 2 (SST2) in growth hormone (GH)-secreting tumors represents the rationale for the clinical use of somatostatin analogs (SSAs) in acromegaly. Recently, the cytoskeletal protein Filamin A (FLNA) has emerged as key modulator of the responsiveness of GH-secreting pituitary tumors to SSAs by regulating SST2 signaling and expression. The aim of this study was to explore FLNA involvement in SST2 intracellular trafficking in tumor somatotroph cells. By biotinylation assay, we found that FLNA silencing abolished octreotide-mediated SST2 internalization in rat GH3 cell line (28.0 ± 2.7 vs. 4 ± 4.3% SST2 internalization, control versus FLNA small interfering RNAs (siRNA) cells, respectively, p < 0.001) and human GH-secreting primary cultured cells (70.3 ± 21.1 vs. 24 ± 19.2% SST2 internalization, control versus FLNA siRNA cells, respectively, p < 0.05). In addition, confocal imaging revealed impaired SST2 recycling to the plasma membrane in FLNA silenced GH3 cells. Coimmunoprecipitation and immunofluorescence experiments showed that FLNA, as well as β-arrestin2, is timely dependent recruited to octreotide-stimulated SST2 receptors both in rat and human tumor somatotroph cells. Although FLNA expression knock down did not prevent the formation of β-arrestin2-SST2 complex in GH3 cells, it significantly impaired efficient SST2 loading into cytosolic vesicles positive for the early endocytic and recycling markers Rab5 and 4, respectively (33.7 ± 8.9% down to 25.9 ± 6.9%, p < 0.05, and 28.4 ± 7.4% down to 17.6 ± 5.7%, p < 0.01, for SST2-Rab5 and SST2-Rab4 colocalization, respectively, in control versus FLNA siRNA cells). Altogether these data support an important role for FLNA in the mediation of octreotide-induced SST2 trafficking in GH-secreting pituitary tumor cells through Rab5 and 4 sorting endosomes.
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Affiliation(s)
- Donatella Treppiedi
- 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
| | - Elena Giardino
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Rosa Catalano
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
- PhD Program in Endocrinological Sciences, Sapienza University of Rome, Rome, Italy
| | - Marco Locatelli
- Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
- Neurosurgery Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Andrea Gerardo Lania
- Endocrine Unit, IRCCS Humanitas Clinical Institute, Humanitas University, Rozzano, Italy
| | - Anna Spada
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
- Endocrinology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Maura Arosio
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
- Endocrinology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Davide Calebiro
- Institute of Pharmacology and Toxicology and Bio-Imaging Center, University of Würzburg, Würzburg, Germany
- Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, United Kingdom
- Centre of Membrane Proteins and Receptors, University of Birmingham, Birmingham, United Kingdom
| | - Giovanna Mantovani
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy,
- Endocrinology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy,
| | - Erika Peverelli
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
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Combination treatments to enhance peptide receptor radionuclide therapy of neuroendocrine tumours. Eur J Nucl Med Mol Imaging 2019; 47:907-921. [DOI: 10.1007/s00259-019-04499-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Accepted: 08/21/2019] [Indexed: 12/11/2022]
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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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Treppiedi D, Jobin ML, Peverelli E, Giardino E, Sungkaworn T, Zabel U, Arosio M, Spada A, Mantovani G, Calebiro D. Single-Molecule Microscopy Reveals Dynamic FLNA Interactions Governing SSTR2 Clustering and Internalization. Endocrinology 2018; 159:2953-2965. [PMID: 29931263 DOI: 10.1210/en.2018-00368] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 06/14/2018] [Indexed: 11/19/2022]
Abstract
The cytoskeletal protein filamin A (FLNA) has been suggested to play an important role in the responsiveness of GH-secreting pituitary tumors to somatostatin receptor subtype 2 (SSTR2) agonists by regulating SSTR2 expression and signaling. However, the underlying mechanisms are unknown. In this study, we use fast multicolor single-molecule microscopy to image individual SSTR2 and FLNA molecules at the surface of living cells with unprecedented spatiotemporal resolution. We find that SSTR2 and FLNA undergo transient interactions, which occur preferentially along actin fibers and contribute to restraining SSTR2 diffusion. Agonist stimulation increases the localization of SSTR2 along actin fibers and, subsequently, SSTR2 clustering and recruitment to clathrin-coated pits (CCPs). Interfering with FLNA-SSTR2 binding with a dominant-negative FLNA fragment increases SSTR2 mobility, hampers the formation and alignment of SSTR2 clusters along actin fibers, and impairs both SSTR2 recruitment to CCPs and SSTR2 internalization. These findings indicate that dynamic SSTR2-FLNA interactions critically control the nanoscale localization of SSTR2 at the plasma membrane and are required for coupling SSTR2 clustering to internalization. These mechanisms explain the critical role of FLNA in the control of SSTR2 expression and signaling and suggest the possibility of targeting SSTR2-FLNA interactions for the therapy of pharmacologically resistant GH-secreting pituitary tumors.
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Affiliation(s)
- Donatella Treppiedi
- Endocrinology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Marie-Lise Jobin
- Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany
- Bio-Imaging Center/Rudolf Virchow Center, University of Würzburg, Würzburg, Germany
| | - Erika Peverelli
- Endocrinology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Elena Giardino
- Endocrinology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Titiwat Sungkaworn
- Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany
- Bio-Imaging Center/Rudolf Virchow Center, University of Würzburg, Würzburg, Germany
| | - Ulrike Zabel
- Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany
- Bio-Imaging Center/Rudolf Virchow Center, University of Würzburg, Würzburg, Germany
| | - Maura Arosio
- Endocrinology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Anna Spada
- Endocrinology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Giovanna Mantovani
- Endocrinology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Davide Calebiro
- Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany
- Bio-Imaging Center/Rudolf Virchow Center, University of Würzburg, Würzburg, Germany
- Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, United Kingdom
- Centre of Membrane Proteins and Receptors (COMPARE), Universities of Birmingham and Nottingham, Birmingham, United Kingdom
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Mazziotti G, Mosca A, Frara S, Vitale G, Giustina A. Somatostatin analogs in the treatment of neuroendocrine tumors: current and emerging aspects. Expert Opin Pharmacother 2017; 18:1679-1689. [PMID: 29067877 DOI: 10.1080/14656566.2017.1391217] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
INTRODUCTION Neuroendocrine tumors (NETs) harbor somatostatin receptors and there is a strong rationale for using somatostatin analogs (SSAs) for treatment of NETs. Areas covered: This article discusses i) pharmacology of somatostatin and its analogs; ii) antisecretory and anti-proliferative effects of SSAs in NETs; iii) efficacy and safety of emerging therapeutic regimens with first generation SSAs administered at either high doses or in combination with antineoplastic drugs; iv) efficacy and safety of pasireotide and chimeric molecules; v) efficacy of radionuclide therapy of NETs using SSAs. Expert opinion: SSAs are the first-line medical therapy for functioning and non-functioning well-differentiated NETs. In patients not responder to first generation SSAs, the increase of drug dose over the conventional regimens, the combination of SSAs with other biotherapies or molecular targeted therapies, the switch to pasireotide or the use of SSAs in radionuclide therapy may improve the therapeutic success.
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Affiliation(s)
| | - Alessandra Mosca
- b Medical Oncology , 'Maggiore della Carità' University Hospital , Novara , Italy
| | - Stefano Frara
- c Chair of Endocrinology , San Raffaele Vita-Salute University , Milan , Italy
| | - Giovanni Vitale
- d Department of Clinical Sciences and Community Health (DISCCO) , University of Milan , Milan , Italy.,e Laboratory of Geriatric and Oncologic Neuroendocrinology Research , Istituto Auxologico Italiano IRCCS , Milan , Italy
| | - Andrea Giustina
- c Chair of Endocrinology , San Raffaele Vita-Salute University , Milan , Italy
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