Insertional mutagenesis by replication-deficient retroviral vectors encoding the large T oncogene

Area of Science:

• Oncogenesis
• Molecular Biology
• Hematopoiesis

Background:

• Replication-deficient retroviral vectors can cause clonal expansion in hematopoietic cells.
• Simian virus 40 large tumor antigen (TAg) is a potent oncogene that inactivates tumor suppressors p53 and Rb.

Purpose of the Study:

• To investigate if retroviral vectors expressing TAg induce leukemia.
• To identify genes cooperating with TAg in leukemogenesis through insertional mutagenesis.

Main Methods:

• Primary hematopoietic stem/progenitor cells and pretransformed 32D cells were transduced with retroviral vectors encoding TAg.
• Transplanted mice were monitored for tumor development.
• Retroviral insertion sites in leukemic clones were analyzed to identify cooperating genes.

Main Results:

• TAg expression induced histiocytic sarcoma or myeloid leukemia in mice with an average survival of 21 weeks.
• TAg introduction into 32D cells rapidly generated monocytic leukemia (approx. 8 weeks).
• Insertional mutagenesis identified genes involved in TAg cooperation pathways, including those regulating proliferation and apoptosis.

Conclusions:

• Vector-mediated insertional mutagenesis is a powerful tool to uncover TAg cooperation genes.
• Findings have implications for retroviral transgenesis in cancer research and somatic gene therapy applications.