title: Bone marrow stroma-secreted cytokines protect JAK2(V617F)-mutated cells from the effects of a JAK2 inhibitor.
abstract: Signals emanating from the bone marrow microenvironment, such as stromal cells, are thought to support the survival and proliferation of the malignant cells in patients with myeloproliferative neoplasms (MPN). To examine this hypothesis, we established a coculture platform [cells cocultured directly (cell-on-cell) or indirectly (separated by micropore membrane)] designed to interrogate the interplay between Janus activated kinase 2-V617F (JAK2(V617F))-positive cells and the stromal cells. Treatment with atiprimod, a potent JAK2 inhibitor, caused marked growth inhibition and apoptosis of human (SET-2) and mouse (FDCP-EpoR) JAK2(V617F)-positive cells as well as primary blood or bone marrow mononuclear cells from patients with polycythemia vera; however, these effects were attenuated when any of these cell types were cocultured (cell-on-cell) with human marrow stromal cell lines (e.g., HS5, NK.tert, TM-R1). Coculture with stromal cells hampered the ability of atiprimod to inhibit phosphorylation of JAK2 and the downstream STAT3 and STAT5 pathways. This protective effect was maintained in noncontact coculture assays (JAK2(V617F)-positive cells separated by 0.4-μm-thick micropore membranes from stromal cells), indicating a paracrine effect. Cytokine profiling of supernatants from noncontact coculture assays detected distinctly high levels of interleukin 6 (IL-6), fibroblast growth factor (FGF), and chemokine C-X-C-motif ligand 10 (CXCL-10)/IFN-γ-inducible 10-kD protein (IP-10). Anti-IL-6, -FGF, or -CXCL-10/IP-10 neutralizing antibodies ablated the protective effect of stromal cells and restored atiprimod-induced apoptosis of JAK2(V617F)-positive cells. Therefore, our results indicate that humoral factors secreted by stromal cells protect MPN clones from JAK2 inhibitor therapy, thus underscoring the importance of targeting the marrow niche in MPN for therapeutic purposes.
authors.affiliation: Department of Leukemia, University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA.
authors.forename: Taghi
authors.initials: T
authors.lastname: Manshouri
authors.forename: Zeev
authors.initials: Z
authors.lastname: Estrov
authors.forename: Alfonso
authors.initials: A
authors.lastname: Quintás-Cardama
authors.forename: Jan
authors.initials: J
authors.lastname: Burger
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhang
authors.forename: Ana
authors.initials: A
authors.lastname: Livun
authors.forename: Liza
authors.initials: L
authors.lastname: Knez
authors.forename: David
authors.initials: D
authors.lastname: Harris
authors.forename: Chad J
authors.initials: CJ
authors.lastname: Creighton
authors.forename: Hagop M
authors.initials: HM
authors.lastname: Kantarjian
authors.forename: Srdan
authors.initials: S
authors.lastname: Verstovsek
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000276:immunology; D001854:Bone Marrow Cells / Q000201:enzymology / Q000276:immunology / Q000502:physiology*; D048708:Cell Growth Processes / Q000187:drug effects / Q000276:immunology; D045744:Cell Line, Tumor; D016207:Cytokines / Q000235:genetics / Q000276:immunology*; D004351:Drug Resistance; D006801:Humans; D015850:Interleukin-6 / Q000235:genetics / Q000276:immunology; D053614:Janus Kinase 2 / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D051379:Mice; D009154:Mutation; D009196:Myeloproliferative Disorders / Q000188:drug therapy* / Q000235:genetics / Q000276:immunology* / Q000473:pathology; D015398:Signal Transduction; D013141:Spiro Compounds / Q000494:pharmacology; D017154:Stromal Cells / Q000187:drug effects / Q000276:immunology; D014162:Transfection
chemical_list: D016207:Cytokines; D015850:Interleukin-6; D013141:Spiro Compounds; C099015:azaspirane; D053614:Janus Kinase 2