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Jayappa KD, Tran B, Gordon VL, Morris CG, Saha S, Farrington CC, O'Connor CM, Zawacki KP, Isaac KM, Kester M, Bender TP, Williams ME, Portell CA, Weber MJ, Narla G. PP2A modulation overcomes multidrug resistance in chronic lymphocytic leukemia via mPTP-dependent apoptosis. J Clin Invest 2023:155938. [PMID: 37166997 DOI: 10.1172/jci155938] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2023] Open
Abstract
Targeted therapies such as venetoclax (Bcl-2 inhibitor) have revolutionized the treatment of chronic lymphocytic leukemia (CLL). We previously reported that persister CLL cells in treated patients overexpress multiple anti-apoptotic proteins and display resistance to pro-apoptotic agents. Here, we demonstrated that multidrug resistant CLL cells in vivo exhibit apoptosis restriction at a premitochondrial level due to insufficient activation of the Bax and Bak proteins. Co-immunoprecipitation analyses with selective BH-domain antagonists revealed that the pleotropic pro-apoptotic protein (Bim) is prevented from activating Bax/Bak by "switching" interactions to other upregulated anti-apoptotic proteins (Mcl-1/Bcl-xL/Bcl-2). Hence, treatments that bypass Bax/Bak restriction are required to deplete these resistant cells in patients. Protein Phosphatase 2A (PP2A) contributes to oncogenesis and treatment resistance. We observed that a small molecule activator of PP2A (SMAP) induced cytotoxicity in multiple cancer cell lines and CLL samples, including multidrug resistant leukemia/lymphoma cells. The SMAP (DT-061) activated apoptosis in multidrug resistant CLL cells through induction of mitochondrial permeability transition pores (mPTP), independent of Bax/Bak. DT-061 inhibited the growth of wild type and Bax/Bak double knockout multidrug resistant CLL cells in a xenograft mouse model. Collectively, we discovered multidrug resistant CLL cells in patients, and validated a pharmacologically tractable pathway to deplete this reservoir.
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Affiliation(s)
- Kallesh D Jayappa
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, United States of America
| | - Brian Tran
- Division of Genetic Medicine, Department of Internal Medicine, University of Michigan, Ann Arbor, United States of America
| | - Vicki L Gordon
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, United States of America
| | - Christopher G Morris
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, United States of America
| | - Shekhar Saha
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, United States of America
| | - Caroline C Farrington
- Division of Genetic Medicine, Department of Internal Medicine, University of Michigan, Ann Arbor, United States of America
| | - Caitlin M O'Connor
- Division of Genetic Medicine, Department of Internal Medicine, University of Michigan, Ann Arbor, United States of America
| | - Kaitin P Zawacki
- Division of Genetic Medicine, Department of Internal Medicine, University of Michigan, Ann Arbor, United States of America
| | - Krista M Isaac
- Division of Hematology/Oncology, University of Virginia School of Medicine, Charlottesville, United States of America
| | - Mark Kester
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, United States of America
| | - Timothy P Bender
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, United States of America
| | - Michael E Williams
- Division of Hematology/Oncology, University of Virginia School of Medicine, Charlottesville, United States of America
| | - Craig A Portell
- Division of Hematology/Oncology, University of Virginia School of Medicine, Charlottesville, United States of America
| | - Michael J Weber
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, United States of America
| | - Goutham Narla
- Division of Genetic Medicine, Department of Internal Medicine, University of Michigan, Ann Arbor, United States of America
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