title: PIM kinases are essential for chronic lymphocytic leukemia cell survival (PIM2/3) and CXCR4-mediated microenvironmental interactions (PIM1).
abstract: Overexpression of the CXCR4 receptor is a hallmark of chronic lymphocytic leukemia (CLL) and is important for CLL cell survival, migration, and interaction with their protective microenvironment. In acute myelogenous leukemia (AML), PIM1 was shown to regulate the surface expression of the CXCR4 receptor. Here, we show that PIM (proviral integration site for Moloney murine leukemia virus) kinases 1-3 are overexpressed and that the CXCR4 receptor is hyperphosphorylated on Ser339 in CLL compared with normal lymphocytes. Furthermore, CXCR4 phosphorylation correlates with PIM1 protein expression and PIM1 transcript levels in CLL. PIM kinase inhibition with three different PIM kinase inhibitors induced apoptosis in CLL cells independent of the presence of protective stromal cells. In addition, PIM inhibition caused dephosphorylation of the CXCR4 receptor on Ser339, resulting in enhanced ligand-dependent CXCR4 internalization and reduced re-externalization after withdrawal of CXCL12. Furthermore, PIM inhibition in CLL cells blocked CXCR4 functions, such as migration toward CXCL12- or CXCL12-induced extracellular signal-regulated kinase (ERK) phosphorylation. In concordance, pretreatment of CLL cells with PIM kinase inhibitors strongly reduced homing of CLL cells toward the bone marrow and the spleen of Rag2(-/-)γc(-/-) mice in vivo. Interestingly, the knockdown of PIM kinases in CLL cells demonstrated diverging functions, with PIM1 regulating CXCR4 surface expression and PIM2 and PIM3 as important for the survival of CLL cells. Our results show that PIM kinase inhibitors are an effective therapeutic option for CLL, not only by impairing PIM2/3-mediated CLL cell survival, but also by blocking the PIM1/CXCR4-mediated interaction of CLL cells with their protective microenvironment.
authors.affiliation: Authors' Affiliations: Department of Hematology/Oncology; Centre of Chronic Immunodeficiency, University Medical Centre Freiburg; Faculty of Biology; BIOSS Centre for Biological Signaling Studies, University of Freiburg, Freiburg, Germany; Department of Biomedicine, University Hospital Basel, Basel, Switzerland; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School; Department of Cancer Biology, Dana-Faber Cancer Institute, Boston, Massachusetts; and Department of Hematology, Leiden University Medical Centre, Leiden, the Netherlands.
authors.forename: Sarah
authors.initials: S
authors.lastname: Decker
authors.forename: Johannes
authors.initials: J
authors.lastname: Finter
authors.forename: Aaron James
authors.initials: AJ
authors.lastname: Forde
authors.forename: Sandra
authors.initials: S
authors.lastname: Kissel
authors.forename: Juerg
authors.initials: J
authors.lastname: Schwaller
authors.forename: Thomas Sebastian
authors.initials: TS
authors.lastname: Mack
authors.forename: Anabel
authors.initials: A
authors.lastname: Kuhn
authors.forename: Nathanael
authors.initials: N
authors.lastname: Gray
authors.forename: Marie
authors.initials: M
authors.lastname: Follo
authors.forename: Hassan
authors.initials: H
authors.lastname: Jumaa
authors.forename: Meike
authors.initials: M
authors.lastname: Burger
authors.forename: Katja
authors.initials: K
authors.lastname: Zirlik
authors.forename: Dietmar
authors.initials: D
authors.lastname: Pfeifer
authors.forename: Chandrasekhar V
authors.initials: CV
authors.lastname: Miduturu
authors.forename: Hermann
authors.initials: H
authors.lastname: Eibel
authors.forename: Hendrik
authors.initials: H
authors.lastname: Veelken
authors.forename: Christine
authors.initials: C
authors.lastname: Dierks
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D001853:Bone Marrow / Q000378:metabolism; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D002465:Cell Movement / Q000187:drug effects; D004268:DNA-Binding Proteins / Q000172:deficiency / Q000235:genetics; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D015870:Gene Expression; D055785:Gene Knockdown Techniques; D006801:Humans; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D018345:Mice, Knockout; D009687:Nuclear Proteins / Q000172:deficiency / Q000235:genetics; D010766:Phosphorylation; D011485:Protein Binding; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D051573:Proto-Oncogene Proteins c-pim-1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D019718:Receptors, CXCR4 / Q000378:metabolism*; D013154:Spleen / Q000378:metabolism; D017154:Stromal Cells / Q000187:drug effects / Q000378:metabolism; D059016:Tumor Microenvironment
chemical_list: D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; C490587:PIM2 protein, human; D047428:Protein Kinase Inhibitors; D011518:Proto-Oncogene Proteins; C499311:RAG2 protein, human; D034741:RNA, Small Interfering; D019718:Receptors, CXCR4; D017346:Protein Serine-Threonine Kinases; D051573:Proto-Oncogene Proteins c-pim-1; C406031:proto-oncogene proteins pim; D048049:Extracellular Signal-Regulated MAP Kinases