title: Loss of drug-induced activation of the CD95 apoptotic pathway in a cisplatin-resistant testicular germ cell tumor cell line.
abstract: Testicular germ cell tumors (TGCTs) are unusually sensitive to cisplatin. In the present study the role of the CD95 death pathway in cisplatin sensitivity of TGCT cells was studied in Tera and its in vitro acquired cisplatin-resistant subclone Tera-CP. Cisplatin induced an increase in CD95 membrane expression, which preceded the onset of apoptosis. Cisplatin-induced apoptosis was efficiently blocked by caspase-8 inhibitor zIETD-fmk in Tera cells, but only partially in Tera-CP cells. In addition, cisplatin induced FADD and caspase-8 recruitment to the CD95 receptor in Tera cells, which was not noticed in Tera-CP cells. Moreover, overexpression of vFLIP reduced apoptosis induction by cisplatin in Tera cells. CD95L-blocking experiments revealed the involvement of CD95/CD95L interactions in cisplatin-induced apoptosis of Tera cells as well as cisplatin-sensitive 833KE TGCT cells. Tera and 833KE cells, treated with low doses of cisplatin, were sensitive for an apoptosis-inducing anti-CD95 antibody. In contrast, CD95L blocking had no effect on cisplatin-induced apoptosis in Tera-CP or Scha, an intrinsic resistant TGCT cell line, nor did anti-CD95 antibody induce additional apoptosis in cisplatin-treated Tera-CP or Scha cells. Taken together, these results show that (1) cisplatin sensitivity of TGCT cells is dependent on the activation of the CD95 death pathway and (2) loss of cisplatin-induced activation of this CD95 signaling pathway may result in resistance to cisplatin.
authors.affiliation: Department of Medical Oncology, University of Groningen, The Netherlands.
authors.forename: D C J
authors.initials: DC
authors.lastname: Spierings
authors.forename: E G E
authors.initials: EG
authors.lastname: de Vries
authors.forename: E
authors.initials: E
authors.lastname: Vellenga
authors.forename: S
authors.initials: S
authors.lastname: de Jong
mesh_terms: D000906:Antibodies / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D002352:Carrier Proteins / Q000378:metabolism; D053181:Caspase 8; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002945:Cisplatin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D019008:Drug Resistance, Neoplasm / Q000502:physiology*; D054278:Embryonal Carcinoma Stem Cells; D004791:Enzyme Inhibitors / Q000494:pharmacology; D053222:Fas Ligand Protein; D018237:Germinoma / Q000188:drug therapy* / Q000378:metabolism* / Q000503:physiopathology; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D008562:Membrane Glycoproteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D008954:Models, Biological; D014411:Neoplastic Stem Cells; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013736:Testicular Neoplasms / Q000188:drug therapy* / Q000378:metabolism* / Q000503:physiopathology; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology; D019014:fas Receptor / Q000187:drug effects* / Q000378:metabolism
chemical_list: D000906:Antibodies; D000970:Antineoplastic Agents; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; C506386:CFLAR protein, human; D002352:Carrier Proteins; D061945:Caspase Inhibitors; D004791:Enzyme Inhibitors; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; D019014:fas Receptor; C505530:CASP8 protein, human; D053181:Caspase 8; D020169:Caspases; D002945:Cisplatin