Development of a Myeloproliferative Disease or a T Cell Lymphoblastic Leukemia in a Murine Bone Marrow Transplant Model of NUP214-ABL1.

Leukemias are often associated with aberrant tyrosine kinase activity that occurs as a result of chromosomal translocations. These mutations are able to confer a proliferative and survival advantage to leukemic cells, as well as cooperate with other mutations that impair cell differentiation, thus leading to the development of leukemia. NUP214-ABL1 is one such recently identified fusion gene that is generated by episomal amplification. The presence of the fusion was recently identified in approximately 6% of patients with T-cell acute lymphoblastic leukemia (T-ALL). By the use of a murine retroviral bone marrow transplantation model we have demonstrated that mice transplanted with NUP214-ABL1 transduced bone marrow cells developed either a myeloproliferative disorder (MPD) with a disease latency of 70 to 118 days or a T cell lymphoblastic leukemia with a disease latency of 115 to 124 days. The myeloproliferative phenotype was characterized by splenomagaly and leukocytosis, and analysis of the histopathology revealed extramedullary hematopoiesis in the liver, lung, kidney and Peyer’s patches, and an increase of peripheral blood neutrophils. Flow cytometry of single cell suspensions from spleen and bone marrow samples of mice with a myeloproliferative phenotype demonstrated an increase of Gr-1⁺/Mac-1⁺ cells (approximately 70%). Two of the mice that were transplanted with NUP214-ABL1 transduced bone marrow cells developed T cell lymphomas that were characterized by large thymomas, a phenotype that is consistent with other models of activated tyrosine kinases over long disease latencies. Histopathological analysis of the thymi revealed effacement of normal thymic architecture as well as T cell infiltrate into the surrounding skeletal muscle. In addition, flow cytometric analysis revealed a significant increase in the CD4⁺/CD8⁺ T cell population in the thymi of these animals. No disease was observed in secondary transplant recipients following 60 days of observation. In conclusion, these results indicate that NUP214-ABL1 is able to cause either a myeloproliferative disease or a T cell lymphoma over longer latencies in mice, the latter being similar to the phenotype observed in humans with expression of the NUP214-ABL1 fusion. These findings provide a useful model for future experiments to determine if there is a contribution of other mutations together with the NUP214-ABL1 fusion towards the development of a T-ALL phenotype in mice.