RECONSTITUTION OF MICE WITH BONE-MARROW CELLS EXPRESSING THE SCL GENEIS INSUFFICIENT TO CAUSE LEUKEMIA

Rearrangement or translocation of the SCL gene is the most common gene tic abnormality observed in human T-cell acute lymphocytic leukemia an d results in the aberrant expression of SCL. To examine the oncogenic potential of this gene, an SCL-retrovirus was used to infect mouse bon e marrow cells, which were then used to reconstitute C57/BL6 mice. Exp ression of SCL did not perturb the composition nor number of day 12 or day 13 colony forming unit-spleen. In total, 141 mice reconstituted w ith SCL-infected bone marrow and 103 control-mice were monitored for u p to 2 years with no difference in survival, hematocrit, white cell co unt, or differential white cell count. As expected, from day 200 onwar ds, mice died due to radiation-induced thymomas; SCL provirus was not detected in these tumors. Thus, despite SCL being strongly implicated in the development of human leukemia, its enforced expression in mice using a retrovirus and bone marrow reconstitution was insufficient to generate leukemia.