Myeloproliferative Disorders |
1 Centre for Infection and Immunity, School of Medicine, Dentistry and Biomedical Sciences, Queens University Belfast, Ireland
2 Dept. of Haematology, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
3 Belfast City Hospitals Trust and Centre for Cancer Research and Cell Biology (CCRCB), Belfast, N. Ireland
4 Ludwig Institute for Cancer Research and The Christian de Duve Institute for Cellular Pathology, Université Catholique de Louvain, Brussels, Belgium
Correspondence: James A. Johnston, Centre for Infection and Immunity, School of Medicine, Dentistry and Biomedical Sciences, QUB, 2nd floor, Whitla Medical Building, 97 Lisburn Rd, Belfast, BT9 7BL, Northern Ireland. E-mail:jim.johnston{at}qub.ac.uk
JAK2 V617F, identified in the majority of patients with myeloproliferative neoplasms, tyrosine phosphorylates SOCS3 and escapes its inhibition. Here, we demonstrate that the JAK2 exon 12 mutants described in a subset of V617F-negative MPN cases, also stabilize tyrosine phosphorylated SOCS3. SOCS3 tyrosine phosphorylation was also observed in peripheral blood mononuclear cells and granulocytes isolated from patients with JAK2 H538QK539L or JAK2 F537-K539delinsL mutations. JAK kinase inhibitors, which effectively inhibited the proliferation of cells expressing V617F or K539L, also caused a dose-dependent reduction in both mutant JAK2 and SOCS3 tyrosine phosphorylation. We propose, therefore, that SOCS3 tyrosine phosphorylation may be a novel bio-marker of myeloproliferative neoplasms resulting from a JAK2 mutation and a potential reporter of effective JAK2 inhibitor therapy currently in clinical development.
Key words: myeloproliferative neoplasms, JAK2, V617F, exon 12, SOCS3.