title: Interferon-gamma sensitizes resistant Ewing's sarcoma cells to tumor necrosis factor apoptosis-inducing ligand-induced apoptosis by up-regulation of caspase-8 without altering chemosensitivity.
abstract: Ewing's sarcoma cells are highly susceptible to apoptosis via tumor necrosis factor apoptosis-inducing ligand (TRAIL). Resistance to TRAIL has been linked to deficient expression of caspase-8 in vitro. Here, we report on the status of caspase-8 expression in tumors from patients with Ewing's sarcoma, the effect of interferon-gamma on caspase-8 expression and apoptosis, and the role of caspase-8 for TRAIL- and chemotherapy-mediated apoptosis in Ewing's sarcoma. Using immunohistochemistry, we show that low expression of caspase-8 is seen in about 24% of tumors. Interferon-gamma induces expression of caspase-8 at concentrations achievable in humans and sensitizes cells to TRAIL. Transfection of wild type but not mutant caspase-8 into caspase-8-deficient Ewing's sarcoma cells restored sensitivity to TRAIL, indicating that up-regulation of caspase-8 is sufficient to restore TRAIL sensitivity. In contrast, no role for caspase-8 in chemotherapy-induced apoptosis was identified, because 1) transfection of caspase-8 or treatment with interferon-gamma did not alter the sensitivity of caspase-8-deficient cells to chemotherapeutics, 2) application of chemotherapy did not select for caspase-8-negative tumor cells in vivo, and 3) the caspase-8 status of tumors did not influence survival after chemotherapy-based protocols. In conclusion, our data provide a rationale for the inclusion of interferon-gamma in upcoming clinical trials with TRAIL.
authors.affiliation: Division of Pediatric Hematology and Oncology, Department of Pediatrics and Adolescent Medicine, Albert-Ludwigs-University, Mathildenstrasse 1, 79106 Freiburg, Germany.
authors.forename: Andrej
authors.initials: A
authors.lastname: Lissat
authors.forename: Thomas
authors.initials: T
authors.lastname: Vraetz
authors.forename: Maria
authors.initials: M
authors.lastname: Tsokos
authors.forename: Ruth
authors.initials: R
authors.lastname: Klein
authors.forename: Matthias
authors.initials: M
authors.lastname: Braun
authors.forename: Nino
authors.initials: N
authors.lastname: Koutelia
authors.forename: Paul
authors.initials: P
authors.lastname: Fisch
authors.forename: Maria E
authors.initials: ME
authors.lastname: Romero
authors.forename: Lauren
authors.initials: L
authors.lastname: Long
authors.forename: Peter
authors.initials: P
authors.lastname: Noellke
authors.forename: Crystal L
authors.initials: CL
authors.lastname: Mackall
authors.forename: Charlotte M
authors.initials: CM
authors.lastname: Niemeyer
authors.forename: Udo
authors.initials: U
authors.lastname: Kontny
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000627:therapeutic use; D017209:Apoptosis / Q000502:physiology*; D001859:Bone Neoplasms / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D053181:Caspase 8 / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002648:Child; D004317:Doxorubicin / Q000627:therapeutic use; D019008:Drug Resistance, Neoplasm; D053595:Embryonic Stem Cells / Q000166:cytology / Q000502:physiology; D005260:Female; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism* / Q000627:therapeutic use; D008297:Male; D012512:Sarcoma, Ewing / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D015996:Survival Rate; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: D000903:Antibiotics, Antineoplastic; D053221:TNF-Related Apoptosis-Inducing Ligand; D004317:Doxorubicin; D007371:Interferon-gamma; D053181:Caspase 8