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.
MeSH terms
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Apoptosis / genetics
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Apoptosis / immunology
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Apoptosis Regulatory Proteins / chemistry
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Apoptosis Regulatory Proteins / genetics
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Apoptosis Regulatory Proteins / immunology
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Apoptosis Regulatory Proteins / metabolism*
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CD30 Ligand / genetics
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CD30 Ligand / immunology
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CD30 Ligand / metabolism*
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Calcium-Calmodulin-Dependent Protein Kinases / chemistry
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Calcium-Calmodulin-Dependent Protein Kinases / genetics
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Calcium-Calmodulin-Dependent Protein Kinases / immunology
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Calcium-Calmodulin-Dependent Protein Kinases / metabolism*
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Cell Line, Tumor
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Cell Proliferation
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DNA Methylation
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Death-Associated Protein Kinases
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Down-Regulation
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Gene Expression Regulation, Enzymologic
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Hodgkin Disease / enzymology
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Hodgkin Disease / genetics
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Hodgkin Disease / immunology*
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Hodgkin Disease / pathology
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Hodgkin Disease / therapy
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Humans
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Immunotherapy*
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Protein Engineering
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / immunology
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Recombinant Fusion Proteins / metabolism*
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Tumor Suppressor Proteins / genetics
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Tumor Suppressor Proteins / immunology
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Tumor Suppressor Proteins / metabolism*
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U937 Cells
Substances
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Apoptosis Regulatory Proteins
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CD30 Ligand
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Recombinant Fusion Proteins
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TNFSF8 protein, human
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Tumor Suppressor Proteins
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DAPK2'-CD30L fusion protein
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DAPK2 protein, human
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Death-Associated Protein Kinases
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Calcium-Calmodulin-Dependent Protein Kinases