title: Differential role of RIP1 in Smac mimetic-mediated chemosensitization of neuroblastoma cells.
abstract: We explored the potential of Smac mimetics, which antagonize Inhibitor of Apoptosis (IAP) proteins, for chemosensitization of neuroblastoma (NB). Here, we report that Smac mimetics, e.g. BV6, prime NB cells for chemotherapeutics including the topoisomerase II inhibitor doxorubicin (DOX) and vinca alkaloids such as Vincristine (VCR), Vinblastine (VBL) and Vinorelbine (VNR). Additionally, BV6 acts in concert with DOX or VCR to suppress long-term clonogenic growth. While BV6 causes rapid downregulation of cellular IAP (cIAP)1 protein and nuclear factor-kappaB (NF-κB) activation, DOX/BV6- or VCR/BV6-induced apoptosis occurs independently of NF-κB or TNFα signaling, since overexpression of dominant-negative IκBα superrepressor or the Tumor Necrosis Factor (TNF)α-blocking antibody Enbrel fail to block cell death. Mechanistic studies reveal that Receptor-interacting protein (RIP)1 is required for DOX/BV6-, but not for VCR/BV6-induced apoptosis, since transient or stable knockdown of RIP1 or the pharmacological RIP1 inhibitor necrostatin-1 significantly reduce apoptosis. By comparison, VCR/BV6-mediated apoptosis critically depends on the mitochondrial pathway. VCR/BV6 cotreatment causes phosphorylation of BCL-2 during mitotic arrest, enhanced activation of BAX and BAK and loss of mitochondrial membrane potential (MMP). Additionally, overexpression of BCL-2 profoundly suppresses VCR/BV6-induced apoptosis. Thus, BV6 sensitizes NB cells to chemotherapy-induced apoptosis via distinct initial signaling mechanisms depending on the chemotherapeutic drug. These findings provide novel mechanistic insights into Smac mimetic-mediated chemosensitization of NB.
authors.affiliation: Institute for Experimental Cancer Research in Pediatrics, Goethe-University, Frankfurt, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Czaplinski
authors.affiliation: Institute for Experimental Cancer Research in Pediatrics, Goethe-University, Frankfurt, Germany.
authors.forename: Behnaz Ahangarian
authors.initials: BA
authors.lastname: Abhari
authors.affiliation: Institute for Experimental Cancer Research in Pediatrics, Goethe-University, Frankfurt, Germany.
authors.forename: Alica
authors.initials: A
authors.lastname: Torkov
authors.affiliation: Institute for Experimental Cancer Research in Pediatrics, Goethe-University, Frankfurt, Germany.
authors.forename: Dominik
authors.initials: D
authors.lastname: Seggewiß
authors.affiliation: Institute for Experimental Cancer Research in Pediatrics, Goethe-University, Frankfurt, Germany.
authors.forename: Manuela
authors.initials: M
authors.lastname: Hugle
authors.affiliation: Institute for Experimental Cancer Research in Pediatrics, Goethe-University, Frankfurt, Germany.|German Cancer Consortium (DKTK), Heidelberg, Germany.|German Cancer Research Center (DKFZ), Heidelberg, Germany.
authors.forename: Simone
authors.initials: S
authors.lastname: Fulda
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D051017:Apoptosis Regulatory Proteins; D040761:Biomimetic Materials; D051928:CD47 Antigen / Q000378:metabolism; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D004317:Doxorubicin / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D004789:Enzyme Activation; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D007211:Indoles / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000378:metabolism*; D009447:Neuroblastoma / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D028861:Nuclear Pore Complex Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D009842:Oligopeptides / Q000494:pharmacology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D016601:RNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors; D059005:Topoisomerase II Inhibitors / Q000494:pharmacology; D014162:Transfection; D014750:Vincristine / Q000494:pharmacology
chemical_list: C119724:AGFG1 protein, human; D000970:Antineoplastic Agents; D051017:Apoptosis Regulatory Proteins; C000595707:BCL2 protein, human; C582180:BV6 peptide; D051928:CD47 Antigen; C497894:CD47 protein, human; C412403:DIABLO protein, human; D007093:Imidazoles; D007211:Indoles; D047908:Intracellular Signaling Peptides and Proteins; D024101:Mitochondrial Proteins; D028861:Nuclear Pore Complex Proteins; D009842:Oligopeptides; D019253:Proto-Oncogene Proteins c-bcl-2; D016601:RNA-Binding Proteins; D059005:Topoisomerase II Inhibitors; C507699:necrostatin-1; D014750:Vincristine; D004317:Doxorubicin; D020169:Caspases
keywords: BCL-2 proteins; RIP1; Smac mimetic; apoptosis; neuroblastoma