title: MPL W515L expression induces TGFβ secretion and leads to an increase in chemokinesis via phosphorylation of THOC5.
abstract: The thrombopoietin receptor (MPL) has been shown to be mutated (MPL W515L) in myelofibrosis and thrombocytosis yet new approaches to treat this disorder are still required. We have previously shown that transcriptome and proteomic effects do not correlate well in oncogene-mediated leukemogenesis. We therefore investigated the effects of MPL W515L using proteomics. The consequences of MPL W515L expression on over 3300 nuclear and 3500 cytoplasmic proteins were assessed using relative quantification mass spectrometry. We demonstrate that MPL W515L expression markedly modulates the CXCL12/CXCR4/CD45 pathway associated with stem and progenitor cell chemotactic movement. We also demonstrated that MPL W515L expressing cells displayed increased chemokinesis which required the MPL W515L-mediated dysregulation of MYC expression via phosphorylation of the RNA transport protein THOC5 on tyrosine 225. In addition MPL W515L expression induced TGFβ secretion which is linked to sphingosine 1-phosphate production and the increased chemokinesis. These studies identify several pathways which offer potential targets for therapeutic intervention in the treatment of MPL W515L-driven malignancy. We validate our approach by showing that CD34+ cells from MPL W515L positive patients display increased chemokinesis and that treatment with a combination of MYC and sphingosine kinase inhibitors leads to the preferential killing of MPL W515L expressing cells.
authors.affiliation: Stem Cell and Leukaemia Proteomics Laboratory, The University of Manchester, Manchester, UK.
authors.forename: Anthony D
authors.initials: AD
authors.lastname: Whetton
authors.affiliation: Stem Cell and Leukaemia Proteomics Laboratory, The University of Manchester, Manchester, UK.
authors.forename: Norhaida Che
authors.initials: NC
authors.lastname: Azmi
authors.affiliation: Stem Cell and Leukaemia Proteomics Laboratory, The University of Manchester, Manchester, UK.
authors.forename: Stella
authors.initials: S
authors.lastname: Pearson
authors.affiliation: Stem Cell and Leukaemia Proteomics Laboratory, The University of Manchester, Manchester, UK.
authors.forename: Ewa
authors.initials: E
authors.lastname: Jaworska
authors.affiliation: Stem Cell and Leukaemia Proteomics Laboratory, The University of Manchester, Manchester, UK.
authors.forename: Liqun
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Stem Cell and Leukaemia Proteomics Laboratory, The University of Manchester, Manchester, UK.
authors.forename: Rognvald
authors.initials: R
authors.lastname: Blance
authors.affiliation: Manchester Pharmacy School, Faculty of Medical and Human Sciences, Manchester Academic Health Science Centre, The University of Manchester, Manchester, UK.
authors.forename: Alexandra C
authors.initials: AC
authors.lastname: Kendall
authors.affiliation: Manchester Pharmacy School, Faculty of Medical and Human Sciences, Manchester Academic Health Science Centre, The University of Manchester, Manchester, UK.
authors.forename: Anna
authors.initials: A
authors.lastname: Nicolaou
authors.affiliation: Stem Cell and Leukaemia Proteomics Laboratory, The University of Manchester, Manchester, UK.
authors.forename: Samuel
authors.initials: S
authors.lastname: Taylor
authors.affiliation: Stem Cell and Leukaemia Proteomics Laboratory, The University of Manchester, Manchester, UK.
authors.forename: Andrew J K
authors.initials: AJ
authors.lastname: Williamson
authors.affiliation: Stem Cell and Leukaemia Proteomics Laboratory, The University of Manchester, Manchester, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Pierce
mesh_terms: D000818:Animals; D016022:Case-Control Studies; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000502:physiology; D049109:Cell Proliferation / Q000502:physiology; D002478:Cells, Cultured; D006801:Humans; D051379:Mice; D009196:Myeloproliferative Disorders / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D053628:Receptors, Thrombopoietin / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D016212:Transforming Growth Factor beta / Q000378:metabolism*
chemical_list: C481270:Mpl protein, mouse; D009687:Nuclear Proteins; D053628:Receptors, Thrombopoietin; C530378:THOC5 protein, human; C559981:THOC5 protein, mouse; D016212:Transforming Growth Factor beta; C082218:MPL protein, human
keywords: MPLW515L; MYC; S1P; THOC5; chemokinesis