title: Smac mimetic sensitizes renal cell carcinoma cells to interferon-α-induced apoptosis.
abstract: The prognosis of metastatic or relapsed renal cell carcinoma (RCC) is still very poor, highlighting the need for new treatment strategies. Here, we identify a cooperative antitumor activity of interferon-α (IFNα) together with the Smac mimetic BV6 that antagonizes antiapoptotic IAP proteins. BV6 and IFNα act together to reduce cell viability and to induce apoptosis in various RCC cell lines. Molecular studies revealed that BV6/IFNα co-treatment triggers apoptosis independently of autocrine/paracrine Tumor Necrosis Factor (TNF)α signaling, since the TNFα-blocking antibody Enbrel fails to rescue cell death. Importantly, knockdown of Receptor-Interacting Protein (RIP)1 significantly decreases BV6/IFNα-mediated apoptosis, whereas the RIP1 kinase inhibitor necrostatin-1 (Nec-1) provides no protection. This demonstrates that RIP1 protein is critically required for BV6/IFNα-induced apoptosis, while RIP1 kinase activity is dispensable, pointing to a scaffold function of RIP1. Consistently, BV6 and IFNα cooperate to trigger the interaction of RIP1, Fas-Associated Death Domain protein (FADD) and caspase-8 to form a cytosolic cell death complex that drives caspase activation. Addition of the broad-range caspase inhibitor N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (zVAD.fmk) significantly protects RCC cells against BV6/IFNα-induced apoptosis, demonstrating that caspase activity is required for apoptosis. In conclusion, the combination approach of IFNα and BV6 represents a promising strategy for cooperative induction of apoptosis in RCC cells, which warrants further investigation.
authors.affiliation: Institute for Experimental Cancer Research in Pediatrics, Goethe-University, Komturstr. 3a, 60528 Frankfurt, Germany; Department of Urology, University Hospital Frankfurt, 60590 Frankfurt, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Reiter
authors.affiliation: Institute for Experimental Cancer Research in Pediatrics, Goethe-University, Komturstr. 3a, 60528 Frankfurt, Germany; German Cancer Consortium (DKTK), Heidelberg, Germany; German Cancer Research Center (DKFZ), Heidelberg, Germany.
authors.forename: Ines
authors.initials: I
authors.lastname: Eckhardt
authors.affiliation: Department of Urology, University Hospital Frankfurt, 60590 Frankfurt, Germany.
authors.forename: Axel
authors.initials: A
authors.lastname: Haferkamp
authors.affiliation: Institute for Experimental Cancer Research in Pediatrics, Goethe-University, Komturstr. 3a, 60528 Frankfurt, Germany; German Cancer Consortium (DKTK), Heidelberg, Germany; German Cancer Research Center (DKFZ), Heidelberg, Germany. Electronic address: simone.fulda@kgu.de.
authors.forename: Simone
authors.initials: S
authors.lastname: Fulda
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D002292:Carcinoma, Renal Cell / Q000188:drug therapy*; D053181:Caspase 8 / Q000378:metabolism; D061945:Caspase Inhibitors / Q000494:pharmacology; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004354:Drug Screening Assays, Antitumor; D004357:Drug Synergism; D006801:Humans; D016898:Interferon-alpha / Q000494:pharmacology*; D007680:Kidney Neoplasms / Q000188:drug therapy*; D018716:Molecular Mimicry; D028861:Nuclear Pore Complex Proteins / Q000378:metabolism; D009842:Oligopeptides / Q000494:pharmacology*; D016601:RNA-Binding Proteins / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: C119724:AGFG1 protein, human; D000970:Antineoplastic Agents; C582180:BV6 peptide; D061945:Caspase Inhibitors; D016898:Interferon-alpha; D028861:Nuclear Pore Complex Proteins; D009842:Oligopeptides; D016601:RNA-Binding Proteins; C532637:SMAC peptide; C439524:TNF protein, human; D014409:Tumor Necrosis Factor-alpha; C505530:CASP8 protein, human; D053181:Caspase 8
keywords: Apoptosis; IAP proteins; Renal cell carcinoma; Smac mimetics