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Uccella S, Leoni E, Kaiser S, Maragliano R, Valerio A, Libera L, Tanda ML, Volante M, Diviani D, La Rosa S. Heterogeneity of TPIT expression in ACTH-secreting extra-pituitary neuroendocrine tumors (NETs) supports the existence of different cellular programs in pancreatic and pulmonary NETs. Virchows Arch 2023; 483:635-643. [PMID: 37726450 DOI: 10.1007/s00428-023-03642-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 08/30/2023] [Accepted: 09/01/2023] [Indexed: 09/21/2023]
Abstract
Extra-pituitary ACTH secretion is associated with a variety of neoplastic conditions and may cause the so-called ectopic ACTH-dependent Cushing syndrome (CS). The clarification of the mechanisms of extra-pituitary ACTH expression would provide potential therapeutic targets for this complex and severe disease. In the adenohypophysis, the transcription factor TPIT, co-operating with other molecules, induces POMC expression and ACTH production. However, no data are currently available on the presence and role of TPIT expression in extra-pituitary ACTH-producing neoplasms. This study was designed to explore TPIT expression in a series of pulmonary and pancreatic ACTH-producing tumors, either CS-associated or not. Forty-one extra-pituitary ACTH-producing neuroendocrine tumors (NETs) were included in the study, encompassing 32 NETs of the lung (LuNETs), 7 of the pancreas (PanNETs), and 2 pheochromocytomas. Of these, 9 LuNETs, all PanNETs, and the two pheochromocytomas were CS-associated. For comparison, 6 NETs of the pituitary gland (PitNETs; 3 ACTH-secreting and 3 ACTH-negative) and 35 ACTH-negative extra-pituitary NETs (15 Lu-NETs and 20 PanNETs) were analyzed. Immunohistochemistry with specific anti-TPIT antibodies and quantitative real-time PCR (qRT-PCR) were performed using standard protocols. TPIT expression was completely absent (protein and mRNA) in PanNETs, pheochromocytomas, and all ACTH-negative NETs. In contrast, it was expressed in 16/32 LuNETs, although with lower levels than in PitNETs. No definite relationship was found between immunohistochemistry TPIT expression and NET grade or the presence of Cushing syndrome. This study further highlights the clinical and biological heterogeneity of extra-pituitary ACTH secretion and suggests that the differences between ACTH-secreting PanNETs and LuNETs may mirror distinct molecular mechanisms underlying POMC expression. Our results point towards the recognition of a real corticotroph-like phenotype of ACTH-producing LuNETs, that is not a feature of ACTH-producing PanNETs.
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Affiliation(s)
- Silvia Uccella
- Pathology Unit, Department of Biomedical Sciences, Humanitas University, Via Rita Levi Montalcini 4, 20090, Pieve Emanuele, Milan, Italy.
- Pathology Service, Humanitas Clinical and Research Center - IRCCS, Via Manzoni 56, 20089, Rozzano, Milan, Italy.
| | - Eleonora Leoni
- Pathology Service, ASST Valle Olona, Busto Arsizio, Varese, Italy
| | - Simon Kaiser
- Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | | | | | - Laura Libera
- Pathology Unit, Department of Medicine and Technological Innovation, University of Insubria, Varese, Italy
| | - Maria Laura Tanda
- Endocrinology Unit, Department of Medicine and Surgery, University of Insubria, Varese, Italy
| | - Marco Volante
- Department of Oncology, University of Turin, Orbassano, Italy
| | - Dario Diviani
- Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Stefano La Rosa
- Pathology Unit, Department of Oncology, ASST Sette Laghi, Varese, Italy
- Pathology Unit, Department of Medicine and Technological Innovation, University of Insubria, Varese, Italy
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Takeuchi H, Koga M, Doi K, Sakurai H. PP2A and its adapter protein IER5 induce the DNA-binding ability and target gene expression of E2F1 via dephosphorylation at serine 375. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2023; 1866:194960. [PMID: 37467925 DOI: 10.1016/j.bbagrm.2023.194960] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 07/12/2023] [Accepted: 07/15/2023] [Indexed: 07/21/2023]
Abstract
The transcription factor E2F1 participates in cell cycle control through transcriptional activation of genes that promote S-phase entry. E2F1 is also linked to the expression of proapoptotic genes, and the loss of E2F1 activity facilitates tumor progression by reducing cellular apoptosis. Phosphorylation controlled by protein kinases and phosphatases is the major posttranslational modification and regulates the cellular levels and transactivator function of E2F1. Here, we characterize the regulatory roles of serine-375 (S375), one of the major phosphorylation sites of E2F1. Cyclin-dependent kinases such as CDK8 phosphorylate at S375 of E2F1, which is dephosphorylated by protein phosphatase 2A (PP2A) containing the B55 regulatory subunit. The PP2A adapter protein IER5 binds to both PP2A/B55 and E2F1 and assists dephosphorylation at S375 by PP2A. S375-dephosphorylated E2F1 exhibits higher DNA-binding affinity than the phosphorylated form. Although the promoter regions of proapoptotic genes are less occupied by E2F1 in cells, an increase in S375-dephosphorylated E2F1 induces preferential binding of E2F1 to the proapoptotic gene promoters and their expression. Our data identify PP2A/B55-IER5 as a critical regulator of E2F1 and suggest that the phosphorylation state of E2F1 is an important determinant for the expression of proapoptotic genes.
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Affiliation(s)
- Hiroto Takeuchi
- Division of Health Sciences, Graduate School of Medical Science, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, Ishikawa 920-0942, Japan
| | - Mayuko Koga
- Division of Health Sciences, Graduate School of Medical Science, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, Ishikawa 920-0942, Japan
| | - Kuriko Doi
- Division of Health Sciences, Graduate School of Medical Science, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, Ishikawa 920-0942, Japan
| | - Hiroshi Sakurai
- Division of Health Sciences, Graduate School of Medical Science, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, Ishikawa 920-0942, Japan.
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Yu R. Is E2F1 a Potential Medical Therapy Target for Cushing Disease? Endocrinology 2022; 163:6649525. [PMID: 35876125 DOI: 10.1210/endocr/bqac117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Indexed: 11/19/2022]
Affiliation(s)
- Run Yu
- Division of Endocrinology, Diabetes, and Metabolism, UCLA David Geffen School of Medicine, Los Angeles, CA 90095, USA
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