title: The tyrosine kinase NPM-ALK, associated with anaplastic large cell lymphoma, binds the intracellular domain of the surface receptor CD30 but is not activated by CD30 stimulation.
abstract: The heterogenous group of anaplastic large cell lymphomas (ALCLs) is characterized by expression of the Ki-1/CD30 antigen, a member of the tumor necrosis factor receptor superfamily. About 40 to 50% of cases diagnosed as ALCL contain a specific chromosomal rearrangement, t(2;5)(p23;q35), resulting in expression of the chimeric tyrosine kinase NPM-ALK. As NPM-ALK-positive lymphomas define a distinct subtype within the group of ALCL, the chimeric protein might be responsible for certain pathogenetic and clinicopathologic characteristics. To better elucidate the function of NPM-ALK, we investigated a possible mechanism for regulation of its activity. We demonstrate that NPM-ALK specifically binds to the intracellular domain of the cytokine receptor CD30. In vitro binding assays revealed that the ALK portion of NPM-ALK mediates interaction of the two proteins. Stimulation of the CD30 receptor by cross-linking with immobilized anti-CD30 antibody results in complete growth inhibition of Karpas 299, an NPM-ALK-positive ALCL cell line, but does not alter proliferation of HDLM-2, a Hodgkin's lymphoma-derived cell line lacking t(2;5). Western blot analysis of coimmunoprecipitated CD30 and NPM-ALK proteins from stimulated Karpas 299 cells showed that the interaction of the proteins is not modified by stimulation. Activation of CD30 neither enhanced NPM-ALK activity measured by autophosphorylation of the chimeric tyrosine kinase nor phosphorylation of phospholipase C-gamma, an NPM-ALK substrate. We conclude that NPM-ALK is not stimulated by CD30 activation, but exists as a constitutively hyperactivated protein. Interaction with CD30 may extend the subcellular localization of NPM-ALK to the microenvironment of membrane-associated proteins.
authors.affiliation: Department of Internal Medicine III, University of Ulm, Germany. gabi.huebinger@medizin.uni-ulm.de
authors.forename: G
authors.initials: G
authors.lastname: Hübinger
authors.forename: I
authors.initials: I
authors.lastname: Scheffrahn
authors.forename: E
authors.initials: E
authors.lastname: Müller
authors.forename: R
authors.initials: R
authors.lastname: Bai
authors.forename: J
authors.initials: J
authors.lastname: Duyster
authors.forename: S W
authors.initials: SW
authors.lastname: Morris
authors.forename: H
authors.initials: H
authors.lastname: Schrezenmeier
authors.forename: L
authors.initials: L
authors.lastname: Bergmann
mesh_terms: D004789:Enzyme Activation; D006801:Humans; D017730:Ki-1 Antigen / Q000378:metabolism*; D017728:Lymphoma, Large-Cell, Anaplastic / Q000378:metabolism*; D011485:Protein Binding; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism*; D015398:Signal Transduction; D014407:Tumor Cells, Cultured
chemical_list: D017730:Ki-1 Antigen; D018124:Receptors, Tumor Necrosis Factor; C107023:p80(NPM-ALK) protein; D011505:Protein-Tyrosine Kinases