JAK2 V617F Tyrosine Kinase Mutation in Leukemia Cell Lines.

It has recently been shown that the majority of patients with polycythemia vera, and substantial numbers of patients with idiopathic myelofibrosis and essential thrombocythemia, carry a single nucleotide mutation in the JAK2 gene. The JAK2 V617F mutation was also found in patients with other myeloproliferative disorders, though at lower percentages. The JAK2 point mutation may contribute to the development of these diseases, and the elucidation of the cellular function of mutated JAK2 might facilitate the development of a suitable drug. In numerous cases, the effects of a mutationally altered protein on cellular functions like proliferation, differentiation or apoptosis, have been revealed using immortalized cell lines that carry the mutation in question. To find such a model system for JAK2 V617F in hematopoietic neoplasia, we tested a panel of 37 cell lines from patients with myeloproliferative disorders, myelodysplastic syndromes (MDS) and the megakaryoblastic variant of acute myeloid leukemia (AML M7) and compared these with cell lines derived from other types of AML (M1-M6), and acute lymphoblastic leukemia (ALL). Cell lines were tested for JAK2 V617F expression applying a DNA tetra-primer amplification refractory mutation system (ARMS), a method that specifically amplifies the normal and mutant sequences plus a positive control band in a single reaction. According to this method, three cell lines carried the JAK2 V167F mutation:

• cell line MB-02 derived from a patient with a history of myelofibrosis and myeloid metaplasia that developed into AML M7;

• cell line MUTZ-8 established from a patient with AML M4 25 years after onset of MDS;

• cell line SET-2 from a patient at the stage of leukemic transformation of essential thrombocythemia.

We present data on these cell lines including JAK2 ARMS and sequencing results, cytogenetic analysis focusing on chromosome 9, and JAK-2 protein expression and activation. In summary, we detected three leukemia cell lines that carry the recently discovered JAK2 mutation. These cell lines promise to represent important research tools in the further analysis of this genetic alteration.