title: Defective p38 mitogen-activated protein kinase signaling impairs chemotaxic but not proliferative responses to stromal-derived factor-1alpha in acute lymphoblastic leukemia.
abstract: The chemokine stromal-derived factor-1alpha (SDF-1alpha) regulates leukemic cell motility and proliferation; however, the importance of these functions in the growth and dissemination of leukemia is unclear. We examined SDF-1alpha-mediated responses of cells from 27 cases of acute lymphoblastic leukemia (ALL). Although cells from the majority of cases showed chemotactic and proliferative responses to SDF-1alpha, a subset of cases did not undergo chemotaxis in response to SDF-1alpha, while still demonstrating dependence on SDF-1alpha for proliferation in stroma-supported cultures. This chemotactic defect was associated with an absence of phosphorylation of p38 mitogen-activated protein kinase (MAPK) induced by SDF-1alpha, and of SDF-1alpha-induced augmentation of beta(1) integrin-mediated adhesion. Signaling through phosphoinositide 3-kinase and MEK was not affected. No correlation was observed between CXCR4 expression and chemotactic function, in vitro migration into bone marrow stromal layers, and engraftment of leukemic cells in nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice. This study suggests that signaling through p38 MAPK is required for ALL cell chemotaxis but not for proliferation, and that the loss of a chemotactic response to SDF-1alpha does not impede engraftment in NOD/SCID mice.
authors.affiliation: Westmead Institute for Cancer Research, Westmead Millennium Institute, University of Sydney, Westmead, New South Wales 2145, Australia. linda_bendall@wmi.usyd.edu.au
authors.forename: Linda J
authors.initials: LJ
authors.lastname: Bendall
authors.forename: Rana
authors.initials: R
authors.lastname: Baraz
authors.forename: Julius
authors.initials: J
authors.lastname: Juarez
authors.forename: Wei
authors.initials: W
authors.lastname: Shen
authors.forename: Kenneth F
authors.initials: KF
authors.lastname: Bradstock
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D001402:B-Lymphocytes / Q000187:drug effects / Q000473:pathology; D002051:Burkitt Lymphoma / Q000201:enzymology* / Q000473:pathology*; D002118:Calcium / Q000378:metabolism; D048708:Cell Growth Processes / Q000187:drug effects / Q000502:physiology; D054377:Chemokine CXCL12; D019743:Chemokines, CXC / Q000494:pharmacology*; D002634:Chemotaxis, Leukocyte / Q000187:drug effects* / Q000502:physiology; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D039041:Integrin alpha4beta1 / Q000378:metabolism; D039081:Integrin alpha5beta1 / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008297:Male; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D008875:Middle Aged; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
chemical_list: C515255:CXCL12 protein, human; D054377:Chemokine CXCL12; D019743:Chemokines, CXC; C515256:Cxcl12 protein, mouse; D039041:Integrin alpha4beta1; D039081:Integrin alpha5beta1; D048051:p38 Mitogen-Activated Protein Kinases; D002118:Calcium