title: Calcium/calmodulin-dependent protein kinase II regulation of c-FLIP expression and phosphorylation in modulation of Fas-mediated signaling in malignant glioma cells.
abstract: Fas, upon cross-linking with Fas ligand (FasL) or Fas agonistic antibody, transduces apoptotic yet also proliferative signals, which have been implicated in tumor pathogenesis. In this study, we investigated the molecular mechanisms that control Fas-mediated signaling in glioma cells. Fas agonistic antibody, CH-11, induced apoptosis in sensitive glioma cells through caspase-8 recruitment to the Fas-mediated death-inducing signaling complex (DISC) where caspase-8 was cleaved to initiate apoptosis through a systematic cleavage of downstream substrates. In contrast, CH-11 stimulated cell growth in resistant glioma cells through recruitment of c-FLIP (cellular Fas-associated death domain (FADD)-like interleukin-1beta-converting enzyme (FLICE)-inhibitory protein) to the Fas-mediated DISC. Three isoforms of long form c-FLIP were detected in glioma cells, but only the phosphorylated isoform was recruited to and cleaved into a p43 intermediate form in the Fas-mediated DISC in resistant cells. Calcium/calmodulin-dependent protein kinase II (CaMK II) activity was up-regulated in resistant cells. Treatment of resistant cells with the CaMK II inhibitor KN-93 inhibited CaMK II activity, reduced c-FLIP expression, inhibited c-FLIP phosphorylation, and rescued CH-11 sensitivity. Transfection of CaMK II cDNA in sensitive cells rendered them resistant to CH-11. These results indicated that CaMK II regulates c-FLIP expression and phosphorylation, thus modulating Fas-mediated signaling in glioma cells.
authors.affiliation: Department of Laboratory Medicine and Pathology and Oncology, University of Alberta, Edmonton, Alberta T6G 2S2, Canada.
authors.forename: Bao Feng
authors.initials: BF
authors.lastname: Yang
authors.forename: Chang
authors.initials: C
authors.lastname: Xiao
authors.forename: Wilson H
authors.initials: WH
authors.lastname: Roa
authors.forename: Peter H
authors.initials: PH
authors.lastname: Krammer
authors.forename: Chunhai
authors.initials: C
authors.lastname: Hao
mesh_terms: D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins; D001596:Benzylamines / Q000494:pharmacology; D015153:Blotting, Western; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000502:physiology*; D002352:Carrier Proteins / Q000378:metabolism*; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism; D016923:Cell Death; D002455:Cell Division; D003432:Cross-Linking Reagents / Q000494:pharmacology; D018076:DNA, Complementary / Q000378:metabolism; D015180:Electrophoresis, Gel, Two-Dimensional; D004791:Enzyme Inhibitors / Q000494:pharmacology; D053222:Fas Ligand Protein; D005910:Glioma / Q000378:metabolism*; D006801:Humans; D015151:Immunoblotting; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins / Q000378:metabolism; D010766:Phosphorylation; D011233:Precipitin Tests; D020033:Protein Isoforms; D011506:Proteins / Q000378:metabolism; D015398:Signal Transduction; D013449:Sulfonamides / Q000494:pharmacology; D013997:Time Factors; D014162:Transfection; D014407:Tumor Cells, Cultured; D015854:Up-Regulation; D000096926:Benzenesulfonamides
chemical_list: D051017:Apoptosis Regulatory Proteins; D001596:Benzylamines; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002352:Carrier Proteins; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases; D003432:Cross-Linking Reagents; D018076:DNA, Complementary; D004791:Enzyme Inhibitors; D053222:Fas Ligand Protein; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; D020033:Protein Isoforms; D011506:Proteins; D013449:Sulfonamides; C506386:CFLAR protein, human; C505661:FASLG protein, human; C109664:caspase-activated DNase inhibitor; C072105:KN 93; D000096926:Benzenesulfonamides; C505530:CASP8 protein, human; C506433:CASP9 protein, human