title: Resistance to TRAIL-induced apoptosis in primitive neuroectodermal brain tumor cells correlates with a loss of caspase-8 expression.
abstract: TNF-related apoptosis-inducing ligand (TRAIL) is a potent inducer of apoptosis in adult malignant glioma and various other human solid tumor models but not in normal tissues. To characterize the TRAIL death pathway in childhood primitive neuroectodermal brain tumor (PNET), 8 human PNET cell lines were tested for TRAIL-induced apoptosis. TRAIL-sensitivity of the PNET cell lines was correlated with mRNA expression levels of TRAIL, its agonistic (TRAIL-R1, TRAIL-R2) and antagonistic (TRAIL-R3, TRAIL-R4) receptors, cellular FLICE-like inhibitory protein (cFLIP), caspase-3 and caspase-8. Three of 8 PNET cell lines tested were susceptible to TRAIL-induced apoptosis. Sensitivity to TRAIL-induced apoptosis did not correlate with mRNA expression of TRAIL receptors or cFLIP. However, all TRAIL-sensitive PNET cell lines expressed caspase-8 mRNA and protein, while none of the five TRAIL-resistant PNET cell lines expressed caspase-8 protein. Treatment with the methyltransferase inhibitor 5-aza-2'-deoxycytidine restored mRNA expression of caspase-8 and TRAIL-sensitivity in formerly TRAIL-resistant PNET cells, suggesting that gene methylation inhibits caspase-8 transcription in these cells. We conclude, that loss of caspase-8 mRNA is an important mechanism of TRAIL-resistance in PNET cells. Treatment with recombinant soluble TRAIL, possibly in combination with methyltransferase inhibitors, represents a promising therapeutic approach for PNET that deserves further investigation.
authors.affiliation: Division of Oncology, The Children's Hospital of Philadelphia, Pennsylvania 19104, USA.
authors.forename: M A
authors.initials: MA
authors.lastname: Grotzer
authors.forename: A
authors.initials: A
authors.lastname: Eggert
authors.forename: T J
authors.initials: TJ
authors.lastname: Zuzak
authors.forename: A J
authors.initials: AJ
authors.lastname: Janss
authors.forename: S
authors.initials: S
authors.lastname: Marwaha
authors.forename: B R
authors.initials: BR
authors.lastname: Wiewrodt
authors.forename: N
authors.initials: N
authors.lastname: Ikegaki
authors.forename: G M
authors.initials: GM
authors.lastname: Brodeur
authors.forename: P C
authors.initials: PC
authors.lastname: Phillips
mesh_terms: D000328:Adult; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins; D001374:Azacitidine / Q000031:analogs & derivatives / Q000494:pharmacology; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D002352:Carrier Proteins / Q000502:physiology; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D002648:Child; D003513:Cycloheximide / Q000494:pharmacology; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000037:antagonists & inhibitors; D019175:DNA Methylation / Q000187:drug effects; D000077209:Decitabine; D004351:Drug Resistance; D004790:Enzyme Induction; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D019169:Jurkat Cells / Q000187:drug effects / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000494:pharmacology*; D009363:Neoplasm Proteins / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D018242:Neuroectodermal Tumors, Primitive / Q000201:enzymology / Q000473:pathology*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis; D012334:RNA, Neoplasm / Q000096:biosynthesis; D018124:Receptors, Tumor Necrosis Factor / Q000187:drug effects; D011994:Recombinant Proteins / Q000494:pharmacology; D053221:TNF-Related Apoptosis-Inducing Ligand; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000201:enzymology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: D000964:Antimetabolites, Antineoplastic; D051017:Apoptosis Regulatory Proteins; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; C506386:CFLAR protein, human; D002352:Carrier Proteins; D004791:Enzyme Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; D009363:Neoplasm Proteins; D011500:Protein Synthesis Inhibitors; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D018124:Receptors, Tumor Necrosis Factor; D011994:Recombinant Proteins; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; D000077209:Decitabine; D003513:Cycloheximide; D004248:DNA (Cytosine-5-)-Methyltransferases; C505530:CASP8 protein, human; C506433:CASP9 protein, human; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases; D001374:Azacitidine