Anti-inflammatory cytokines hepatocyte growth factor and interleukin-11 are over-expressed in Polycythemia vera and contribute to the growth of clonal erythroblasts independently of JAK2V617F.
The V617F activating mutation of janus kinase 2 (JAK2), a kinase essential for cytokine signalling, characterizes Polycythemia vera (PV), one of the myeloproliferative neoplasms (MPN). However, not all MPNs carry mutations of JAK2, and in JAK2-mutated patients, expression of JAK2V617F does not always result in clone expansion. In the present study, we provide evidence that inflammation-linked cytokines are required for the growth of JAK2V617F-mutated erythroid progenitors. In a first series of experiments, we searched for cytokines over-expressed in PV using cytokine antibody (Ab) arrays, and enzyme-linked immunosorbent assays for analyses of serum and bone marrow (BM) plasma, and quantitative reverse transcription-PCRs for analyses of cells purified from PV patients and controls. We found that PV patients over-expressed anti-inflammatory hepatocyte growth factor (HGF) and interleukin-11 (IL-11), BM mesenchymal stromal cells (BMMSCs) and erythroblasts being the main producers. In a second series of experiments, autocrine/paracrine cytokine stimulation of erythroblasts was blocked using neutralizing Abs specific for IL-11 or c-MET, the HGF receptor. The growth of JAK2V617F-mutated HEL cells and PV erythroblasts was inhibited, indicating that JAK2-mutated cells depend on HGF and IL-11 for their growth. Additional experiments showed that transient expression of JAK2V617F in BaF-3/erythropoietin receptor cells, and invalidation of JAK2V617F in HEL cells using anti-JAK2 small interfering RNA, did not affect HGF and IL-11 expression. Thus, anti-inflammatory HGF and IL-11 are upregulated in PV and their overproduction is not a consequence of JAK2V617F. As both cytokines contribute to the proliferation of PV erythroblasts, blocking the c-MET/HGF/IL-11 pathways could be of interest as an additional therapeutic option in PV.
INSERM UMR 892, Institut de Biologie, Centre Hospitalier Universitaire, Nantes, France.
M
M
Boissinot
C
C
Cleyrat
M
M
Vilaine
Y
Y
Jacques
I
I
Corre
S
S
Hermouet
D049109:Cell Proliferation; D002999:Clone Cells; D016207:Cytokines / Q000032:analysis / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D004900:Erythroblasts / Q000378:metabolism*; D005260:Female; D020869:Gene Expression Profiling; D017228:Hepatocyte Growth Factor / Q000378:metabolism*; D006801:Humans; D007249:Inflammation / Q000378:metabolism; D017370:Interleukin-11 / Q000378:metabolism*; D053614:Janus Kinase 2 / Q000235:genetics*; D008297:Male; D009154:Mutation; D011087:Polycythemia Vera / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology; D015854:Up-Regulation
D016207:Cytokines; C508611:IL11 protein, human; D017370:Interleukin-11; D012333:RNA, Messenger; D017228:Hepatocyte Growth Factor; C507924:JAK2 protein, human; D053614:Janus Kinase 2