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Updated: Sep 6, 2025
Evaluation of Abnormal Growth-related Genes of Hematopoietic Stem and Progenitor Cells by Combining CRISPR/Cas9 Technology with Cell Counting
Published on: May 2, 2025
Degradation of GSPT1 causes TP53-independent cell death in leukemia while sparing normal hematopoietic stem cells
Rob S Sellar1,2,3, Adam S Sperling2,3,4, Mikołaj Słabicki2,3
1Department of Haematology, UCL Cancer Institute, University College London, London, United Kingdom.
Abstract:
Targeted protein degradation is a rapidly advancing and expanding therapeutic approach. Drugs that degrade GSPT1 via the CRL4CRBN ubiquitin ligase are a new class of cancer therapy in active clinical development with evidence of activity against acute myeloid leukemia in early-phase trials. However, other than activation of the integrated stress response, the downstream effects of GSPT1 degradation leading to cell death are largely undefined, and no murine models are available to study these agents. We identified the domains of GSPT1 essential for cell survival and show that GSPT1 degradation leads to impaired translation termination, activation of the integrated stress response pathway, and TP53-independent cell death. CRISPR/Cas9 screens implicated decreased translation initiation as protective following GSPT1 degradation, suggesting that cells with higher levels of translation are more susceptible to the effects of GSPT1 degradation. We defined 2 Crbn amino acids that prevent Gspt1 degradation in mice, generated a knockin mouse with alteration of these residues, and demonstrated the efficacy of GSPT1-degrading drugs in vivo with relative sparing of numbers and function of long-term hematopoietic stem cells. Our results provide a mechanistic basis for the use of GSPT1 degraders for the treatment of cancer, including TP53-mutant acute myeloid leukemia.
Insights
Targeted protein degradation using GSPT1 degraders shows promise for cancer therapy, particularly acute myeloid leukemia. This study reveals GSPT1 degradation impairs translation termination, leading to cell death, and establishes a new mouse model for further research.
Area of Science:
- Molecular Biology
- Cancer Therapeutics
- Drug Development
Background:
- Targeted protein degradation is an emerging therapeutic strategy.
- GSPT1 degraders, utilizing the CRL4CRBN ubiquitin ligase, represent a novel class of cancer therapeutics.
- Current understanding of GSPT1 degradation's downstream effects and lack of suitable animal models limit research.
Purpose of the Study:
- To elucidate the downstream effects of GSPT1 degradation on cell death.
- To identify mechanisms of cellular resistance or susceptibility to GSPT1 degradation.
- To develop a murine model for studying GSPT1-degrading agents in vivo.
Main Methods:
- CRISPR/Cas9 screening to identify protective mechanisms against GSPT1 degradation.
- Analysis of translation termination and initiation pathways.
- Generation of a GSPT1-degrading drug-sensitive mouse model by altering CRBN residues.
Main Results:
- GSPT1 degradation impairs translation termination, activates the integrated stress response, and induces TP53-independent cell death.
- Decreased translation initiation confers protection against GSPT1 degradation, indicating higher translation levels increase susceptibility.
- A novel knockin mouse model was created, demonstrating in vivo efficacy of GSPT1 degraders with preserved long-term hematopoietic stem cells.
Conclusions:
- GSPT1 degradation disrupts protein synthesis, leading to cancer cell death through a TP53-independent pathway.
- Translation initiation levels influence cellular sensitivity to GSPT1 degraders.
- The developed murine model enables in vivo evaluation of GSPT1 degraders, supporting their therapeutic application in cancers like TP53-mutant acute myeloid leukemia.
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