Influence of casein kinase II in tumor necrosis factor-related apoptosis-inducing ligand-induced apoptosis in human rhabdomyosarcoma cells.
Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induces apoptosis via the death receptors DR4 and DR5 in transformed cells in vitro and exhibits potent antitumor activity in vivo with minor side effects. Protein kinase casein kinase II (CK2) is increased in response to diverse growth stimuli and is aberrantly elevated in a variety of human cancers. Rhabdomyosarcoma tumors are the most common soft-tissue sarcoma in childhood. In this investigation, we demonstrate that CK2 is a key survival factor that protects tumor cells from TRAIL-induced apoptosis. We have demonstrated that inhibition of CK2 phosphorylation events by 5,6-dichlorobenzimidazole (DRB) resulted in dramatic sensitization of tumor cells to TRAIL-induced apoptosis. CK2 inhibition also induced rapid cleavage of caspase-8, -9, and -3, as well as the caspase substrate poly(ADP-ribose) polymerase after TRAIL treatment. Overexpression of Bcl-2 protected cells from TRAIL-induced apoptosis in the presence of the CK2 inhibitor. Death signaling by TRAIL in these cells was Fas-associated death domain and caspase dependent because dominant negative Fas-associated death domain or the cowpox interleukin 1beta-converting enzyme inhibitor protein cytokine response modifier A prevented apoptosis in the presence of DRB. Analysis of death-inducing signaling complex (DISC) formation demonstrated that inhibition of CK2 by DRB increased the level of recruitment of procaspase-8 to the DISC and enhanced caspase-8-mediated cleavage of Bid, thereby increasing the release of the proapoptotic factors cytochrome c, HtrA2/Omi, Smac/DIABLO, and apoptosis inducing factor (AIF) from the mitochondria, with subsequent degradation of X-linked inhibitor of apoptosis protein (XIAP). To further interfere with CK2 function, JR1 and Rh30 cells were transfected with either short hairpin RNA targeted to CK2alpha or kinase-inactive CK2alpha (K68M) or CK2alpha' (K69M). Data show that the CK2 kinase activity was abrogated and that TRAIL sensitivity in both cell lines was increased. Silencing of CK2alpha expression with short hairpin RNA was also associated with degradation of XIAP. These findings suggest that CK2 regulates TRAIL signaling in rhabdomyosarcoma by modulating TRAIL-induced DISC formation and XIAP expression.
Division of Molecular Therapeutics, Department of Hematology-Oncology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA.
Kamel
K
Izeradjene
Leslie
L
Douglas
Addison
A
Delaney
Janet A
JA
Houghton
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins; D001562:Benzimidazoles / Q000494:pharmacology; D047390:Casein Kinase II / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D053178:Caspase 6; D053181:Caspase 8; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm; D053200:Fas-Associated Death Domain Protein; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000494:pharmacology*; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D020125:Mutation, Missense; D010766:Phosphorylation / Q000187:drug effects; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism; D012208:Rhabdomyosarcoma / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D015398:Signal Transduction; D053221:TNF-Related Apoptosis-Inducing Ligand; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D051636:X-Linked Inhibitor of Apoptosis Protein
C110962:5,6-dichlorobenzimidazole; D048868:Adaptor Proteins, Signal Transducing; D051017:Apoptosis Regulatory Proteins; D001562:Benzimidazoles; C505533:FADD protein, human; D053200:Fas-Associated Death Domain Protein; D007527:Isoenzymes; D008562:Membrane Glycoproteins; D021122:Protein Subunits; D011506:Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D034741:RNA, Small Interfering; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor; D053221:TNF-Related Apoptosis-Inducing Ligand; C505639:TNFRSF10B protein, human; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; D051636:X-Linked Inhibitor of Apoptosis Protein; C496866:XIAP protein, human; D049452:Green Fluorescent Proteins; D047390:Casein Kinase II; C505514:CASP6 protein, human; C505530:CASP8 protein, human; D053178:Caspase 6; D053181:Caspase 8; D020169:Caspases