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Retroviral Scanning: Mapping MLV Integration Sites to Define Cell-specific Regulatory Regions
Published on: May 28, 2017
Leukemia induction after a single retroviral vector insertion in Evi1 or Prdm16
U Modlich1, A Schambach, M H Brugman
1Department of Experimental Hematology, Hannover Medical School, Hannover, Germany.
Leukemia
|May 23, 2008
Summary
Retroviral vectors used for gene therapy can cause leukemia by activating cancer genes like Evi1 or Prdm16. This study shows insertional mutagenesis is required for leukemia induction by interleukin-2 receptor common gamma-chain (IL2RG) vectors.
Area of Science:
- Gene therapy vector safety
- Retroviral insertional mutagenesis
- Leukemogenesis research
Background:
- Replication-defective retroviral vectors can activate proto-oncogenes, leading to leukemia.
- Interleukin-2 receptor common gamma-chain (IL2RG) is crucial for correcting X-linked severe combined immunodeficiency.
Purpose of the Study:
- To assess the leukemogenic potential of vectors expressing IL2RG.
- To investigate the role of insertional mutagenesis in IL2RG vector-mediated leukemogenesis.
Main Methods:
- Utilized self-inactivating (SIN) gamma-retroviral vectors expressing IL2RG.
- Performed serial bone marrow transplantation in C57Bl6/J mice.
- Monitored mice for up to 18 months for leukemic progression and vector insertion sites.
Main Results:
- SIN vectors with strong enhancers induced clonal imbalance with specific insertion preferences.
- Ectopic IL2RG expression alone did not trigger leukemia.
- Leukemic clones consistently harbored vector insertions in Evi1 or Prdm16, sufficient for initiating leukemogenesis.
Conclusions:
- Upregulation of Evi1 or Prdm16 by vector insertion is sufficient to initiate a leukemogenic cascade.
- Insertional mutagenesis is a necessary mechanism for leukemia induction by IL2RG vectors.
- Improved vector design is crucial to mitigate the risk of insertional mutagenesis in gene therapy.
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