title: Pediatric rhabdomyosarcoma cell lines are resistant to Fas-induced apoptosis and highly sensitive to TRAIL-induced apoptosis.
abstract: Seven pediatric rhabdomyosarcoma (RMS) cell lines were resistant to the induction of apoptosis via the Fas death receptor. In contrast, four of seven lines (RD, Rh1, Rh18, and Rh30) were highly sensitive to tumor necrosis factor-alpha-related apoptosis-inducing ligand (TRAIL). TRAIL induced apoptosis within 4 h and also reduced clonogenic survival, both reversible by caspase inhibitors. DR5 (but not DR4) was expressed at high level in all cell lines. Expression of the decoy receptors DcR1 and DcR2 did not correlate with TRAIL sensitivity. All RMS lines expressed the adapter molecule FADD, and six of seven expressed procaspase-8. Expression of the inhibitory proteins c-FLIPL and c-FLIPs was high in three TRAIL-sensitive (RD, Rh1, and Rh30) and two TRAIL-resistant (Rh28 and Rh41) lines. All RMS lines expressed Bid and procaspases-3, -6, -7, and -9. Procaspases-8 and -10 were highest in TRAIL-sensitive RMS (RD, Rh1, and Rh30), and procaspase-10 was not expressed in Rh18, Rh36, or Rh41. TRAIL induced loss of mitochondrial membrane potential in TRAIL-sensitive Rh1 but not in TRAIL-resistant Rh41 cells. There was no correlation between expression of members of the Bcl-2 family (Bcl-2, Bcl-xL, Bax, and Bak) and TRAIL sensitivity. TRAIL-sensitive Rh18 expressed procaspase-8 in the absence of procaspase-10 and c-FLIP, and procaspase-10 was not detected in TRAIL-resistant Rh41 in the presence of procaspase-8 and c-FLIP. Data suggest that caspase-8 may be sufficient to deliver the TRAIL-induced apoptotic signal in the absence of both caspase-10 and c-FLIP (Rh18) but not in the presence of c-FLIP (Rh41). In RD, Rh1, and Rh30, the presence of c-FLIP may require amplification of the apoptotic signal via caspase-10.
authors.affiliation: Department of Hematology-Oncology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA.
authors.forename: I
authors.initials: I
authors.lastname: Petak
authors.forename: L
authors.initials: L
authors.lastname: Douglas
authors.forename: D M
authors.initials: DM
authors.lastname: Tillman
authors.forename: R
authors.initials: R
authors.lastname: Vernes
authors.forename: J A
authors.initials: JA
authors.lastname: Houghton
mesh_terms: D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins; D015153:Blotting, Western; D020169:Caspases / Q000378:metabolism; D002455:Cell Division; D002648:Child; D002675:Child, Preschool; D004305:Dose-Response Relationship, Drug; D019008:Drug Resistance, Neoplasm; D005434:Flow Cytometry; D006801:Humans; D008562:Membrane Glycoproteins / Q000378:metabolism*; D008564:Membrane Potentials; D008928:Mitochondria / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012208:Rhabdomyosarcoma / Q000473:pathology*; D012260:Ribonucleases / Q000378:metabolism; D015398:Signal Transduction; D053221:TNF-Related Apoptosis-Inducing Ligand; D013997:Time Factors; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*; D019014:fas Receptor / Q000378:metabolism*
chemical_list: D051017:Apoptosis Regulatory Proteins; D008562:Membrane Glycoproteins; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; D019014:fas Receptor; D012260:Ribonucleases; D020169:Caspases