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Fried W, Tyagi M, Minakhin L, Chandramouly G, Tredinnick T, Ramanjulu M, Auerbacher W, Calbert M, Rusanov T, Hoang T, Borisonnik N, Betsch R, Krais JJ, Wang Y, Vekariya UM, Gordon J, Morton G, Kent T, Skorski T, Johnson N, Childers W, Chen XS, Pomerantz RT. Discovery of a small-molecule inhibitor that traps Polθ on DNA and synergizes with PARP inhibitors. Nat Commun 2024; 15:2862. [PMID: 38580648 PMCID: PMC10997755 DOI: 10.1038/s41467-024-46593-1] [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: 08/14/2023] [Accepted: 03/04/2024] [Indexed: 04/07/2024] Open
Abstract
The DNA damage response (DDR) protein DNA Polymerase θ (Polθ) is synthetic lethal with homologous recombination (HR) factors and is therefore a promising drug target in BRCA1/2 mutant cancers. We discover an allosteric Polθ inhibitor (Polθi) class with 4-6 nM IC50 that selectively kills HR-deficient cells and acts synergistically with PARP inhibitors (PARPi) in multiple genetic backgrounds. X-ray crystallography and biochemistry reveal that Polθi selectively inhibits Polθ polymerase (Polθ-pol) in the closed conformation on B-form DNA/DNA via an induced fit mechanism. In contrast, Polθi fails to inhibit Polθ-pol catalytic activity on A-form DNA/RNA in which the enzyme binds in the open configuration. Remarkably, Polθi binding to the Polθ-pol:DNA/DNA closed complex traps the polymerase on DNA for more than forty minutes which elucidates the inhibitory mechanism of action. These data reveal a unique small-molecule DNA polymerase:DNA trapping mechanism that induces synthetic lethality in HR-deficient cells and potentiates the activity of PARPi.
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Affiliation(s)
- William Fried
- Molecular and Computational Biology, Department of Biological Sciences and Chemistry, University of Southern California, Los Angeles, CA, USA
| | - Mrityunjay Tyagi
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, 19107, USA
| | - Leonid Minakhin
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, 19107, USA
| | - Gurushankar Chandramouly
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, 19107, USA
| | - Taylor Tredinnick
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, 19107, USA
| | - Mercy Ramanjulu
- Recombination Therapeutics, Pennsylvania Biotechnology Center, Doylestown, PA, 18902, USA
| | - William Auerbacher
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, 19107, USA
| | - Marissa Calbert
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, 19107, USA
- Fels Cancer Institute for Personalized Medicine, Philadelphia, PA, USA
| | - Timur Rusanov
- Department of Pharmacology and Regenerative Medicine, University of Illinois at Chicago, Chicago, IL, 60612, USA
| | | | | | - Robert Betsch
- Nuclear Dynamics Program, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - John J Krais
- Nuclear Dynamics Program, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Yifan Wang
- Nuclear Dynamics Program, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Umeshkumar M Vekariya
- Fels Cancer Institute for Personalized Medicine, Philadelphia, PA, USA
- Department of Cancer and Cellular Biology, Temple University Lewis Katz School of Medicine, Philadelphia, PA, USA
| | - John Gordon
- Fels Cancer Institute for Personalized Medicine, Philadelphia, PA, USA
| | - George Morton
- Moulder Center for Drug Discovery Research, Temple University School of Pharmacy, Philadelphia, PA, USA
| | - Tatiana Kent
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, 19107, USA
| | - Tomasz Skorski
- Fels Cancer Institute for Personalized Medicine, Philadelphia, PA, USA
- Department of Cancer and Cellular Biology, Temple University Lewis Katz School of Medicine, Philadelphia, PA, USA
| | - Neil Johnson
- Nuclear Dynamics Program, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Wayne Childers
- Recombination Therapeutics, Pennsylvania Biotechnology Center, Doylestown, PA, 18902, USA
- Moulder Center for Drug Discovery Research, Temple University School of Pharmacy, Philadelphia, PA, USA
| | - Xiaojiang S Chen
- Molecular and Computational Biology, Department of Biological Sciences and Chemistry, University of Southern California, Los Angeles, CA, USA
- Recombination Therapeutics, Pennsylvania Biotechnology Center, Doylestown, PA, 18902, USA
| | - Richard T Pomerantz
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, 19107, USA.
- Recombination Therapeutics, Pennsylvania Biotechnology Center, Doylestown, PA, 18902, USA.
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