title: Targeted restoration of down-regulated DAPK2 tumor suppressor activity induces apoptosis in Hodgkin lymphoma cells.
abstract: Death-associated protein kinase 2 (DAPK2) is a calcium/calmodulin-regulated proapoptotic serine/threonine kinase that acts as a tumor suppressor. Here we show that DAPK2 is down-regulated in Hodgkin lymphoma-derived tumor cell lines and that promoter-region hypermethylation is one mechanism for DAPK2 inactivation. To determine whether selective reconstitution of DAPK2 catalytic activity in these cells could induce apoptosis, we created a fusion protein comprising a human CD30 ligand conjugated to a human DAPK2 calmodulin-deletion mutant. Thus, recombinant immunokinase DAPK2'-CD30L has a constitutive kinase activity with enhanced proapoptotic function. We show that this immunokinase fusion protein inhibits cell proliferation and induces apoptotic cell death specifically in CD30/DAPK2-negative tumor cell lines. This proof-of-concept study provides the first demonstration of therapeutic strategies based on the restoration of a defective, tumor-suppressing kinase activity by a novel class of recombinant immunotherapeutics.
authors.affiliation: Department of Experimental Medicine and Immunotherapy, Chair of Applied Medical Engineering, Helmholtz-Institute for Biomedical Engineering, University Hospital RWTH Aachen, Aachen, Germany. tur@hia.rwth-aachen.de
authors.forename: Mehmet Kemal
authors.initials: MK
authors.lastname: Tur
authors.forename: Inga
authors.initials: I
authors.lastname: Neef
authors.forename: Edgar
authors.initials: E
authors.lastname: Jost
authors.forename: Oliver
authors.initials: O
authors.lastname: Galm
authors.forename: Gernot
authors.initials: G
authors.lastname: Jäger
authors.forename: Michael
authors.initials: M
authors.lastname: Stöcker
authors.forename: Markus
authors.initials: M
authors.lastname: Ribbert
authors.forename: Rainhardt
authors.initials: R
authors.lastname: Osieka
authors.forename: Uwe
authors.initials: U
authors.lastname: Klinge
authors.forename: Stefan
authors.initials: S
authors.lastname: Barth
mesh_terms: D017209:Apoptosis / Q000235:genetics / Q000276:immunology; D051017:Apoptosis Regulatory Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D053285:CD30 Ligand / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D019175:DNA Methylation; D064550:Death-Associated Protein Kinases; D015536:Down-Regulation; D015971:Gene Expression Regulation, Enzymologic; D006689:Hodgkin Disease / Q000201:enzymology / Q000235:genetics / Q000276:immunology* / Q000473:pathology / Q000628:therapy; D006801:Humans; D007167:Immunotherapy; D015202:Protein Engineering; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D020298:U937 Cells
chemical_list: D051017:Apoptosis Regulatory Proteins; D053285:CD30 Ligand; D011993:Recombinant Fusion Proteins; C505774:TNFSF8 protein, human; D025521:Tumor Suppressor Proteins; C544074:DAPK2'-CD30L fusion protein; C579104:DAPK2 protein, human; D064550:Death-Associated Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases