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Nguyen A, Mustafa AHM, Leydecker AK, Halilovic M, Murr J, Butter F, Krämer OH. The protein phosphatase-2A subunit PR130 is involved in the formation of cytotoxic protein aggregates in pancreatic ductal adenocarcinoma cells. Cell Commun Signal 2024; 22:217. [PMID: 38570831 PMCID: PMC10993613 DOI: 10.1186/s12964-024-01597-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2023] [Accepted: 03/26/2024] [Indexed: 04/05/2024] Open
Abstract
As a major source of cellular serine and threonine phosphatase activity, protein phosphatase-2A (PP2A) modulates signaling pathways in health and disease. PP2A complexes consist of catalytic, scaffolding, and B-type subunits. Seventeen PP2A B-type subunits direct PP2A complexes to selected substrates. It is ill-defined how PP2A B-type subunits determine the growth and drug responsiveness of tumor cells. Pancreatic ductal adenocarcinoma (PDAC) is a disease with poor prognosis. We analyzed the responses of murine and human mesenchymal and epithelial PDAC cells to the specific PP2A inhibitor phendione. We assessed protein levels by immunoblot and proteomics and cell fate by flow cytometry, confocal microscopy, and genetic manipulation. We show that murine mesenchymal PDAC cells express significantly higher levels of the PP2A B-type subunit PR130 than epithelial PDAC cells. This overexpression of PR130 is associated with a dependency of such metastasis-prone cells on the catalytic activity of PP2A. Phendione induces apoptosis and an accumulation of cytotoxic protein aggregates in murine mesenchymal and human PDAC cells. These processes occur independently of the frequently mutated tumor suppressor p53. Proteomic analyses reveal that phendione upregulates the chaperone HSP70 in mesenchymal PDAC cells. Inhibition of HSP70 promotes phendione-induced apoptosis and phendione promotes a proteasomal degradation of PR130. Genetic elimination of PR130 sensitizes murine and human PDAC cells to phendione-induced apoptosis and protein aggregate formation. These data suggest that the PP2A-PR130 complex dephosphorylates and thereby prevents the aggregation of proteins in tumor cells.
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Affiliation(s)
- Alexandra Nguyen
- Institute of Toxicology, University Medical Center of the Johannes Gutenberg University Mainz, Obere Zahlbacher St. 67, 55131, Mainz, Germany
| | - Al-Hassan M Mustafa
- Institute of Toxicology, University Medical Center of the Johannes Gutenberg University Mainz, Obere Zahlbacher St. 67, 55131, Mainz, Germany
- Department of Zoology, Faculty of Science, Aswan University, Aswan, Egypt
| | - Alessa K Leydecker
- Institute of Toxicology, University Medical Center of the Johannes Gutenberg University Mainz, Obere Zahlbacher St. 67, 55131, Mainz, Germany
| | - Melisa Halilovic
- Institute of Toxicology, University Medical Center of the Johannes Gutenberg University Mainz, Obere Zahlbacher St. 67, 55131, Mainz, Germany
| | - Janine Murr
- Medical Clinic and Polyclinic II, Klinikum Rechts Der Isar, Technical University Munich, 81675, Munich, Germany
| | - Falk Butter
- Institute of Molecular Biology (IMB), Ackermannweg 4, 55128, Mainz, Germany
- Federal Research Institute for Animal Health, Südufer 10, 17493, Greifswald, Insel Riems, Germany
| | - Oliver H Krämer
- Institute of Toxicology, University Medical Center of the Johannes Gutenberg University Mainz, Obere Zahlbacher St. 67, 55131, Mainz, Germany.
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