title: 5-Fluorouracil-induced RNA stress engages a TRAIL-DISC-dependent apoptosis axis facilitated by p53.
abstract: Despite recent advances in targeted therapeutics, administration of 5-fluorouracil (5-FU) remains a common clinical strategy for post-surgical treatment of solid tumors. Although it has been proposed that RNA metabolism is disturbed by 5-FU treatment, the key cytotoxic response is believed to be enzymatic inhibition of thymidylate synthase resulting in nucleotide pool disproportions. An operating p53 tumor suppressor signaling network is in many cases essential for the efficiency of chemotherapy, and malfunctions within this system remain a clinical obstacle. Since the fate of chemotherapy-insensitive tumor cells is rarely described, we performed a comparative analysis of 5-FU toxicity in p53-deficient cells and conclude that p53 acts as a facilitator rather than a gatekeeper of cell death. Although p53 can act as a regulator of several cellular stress responses, no rerouting of cell death mode was observed in absence of the tumor suppressor. Thus, the final death outcome of 5-FU-treated p53-/- cells is demonstrated to be caspase-dependent, but due to a slow pace, accumulation of mitochondrial reactive oxygen species contributes to necrotic characteristics. The oligomerization status of the p53 target gene DR5 is determined as a significant limiting factor for the initiation of caspase activity in an intracellular TRAIL-dependent manner. Using several experimental approaches, we further conclude that RNA-rather than DNA-related stress follows by caspase activation irrespectively of p53 status. A distinct 5-FU-induced stress mechanism is thereby functionally connected to a successive and discrete cell death signaling pathway. Finally, we provide evidence that silencing of PARP-1 function may be an approach to specifically target p53-deficient cells in 5-FU combinatorial treatment strategies. Together, our results disclose details of impaired cell death signaling engaged as a consequence of 5-FU chemotherapy. Obtained data will contribute to the comprehension of factors restraining 5-FU efficiency, and by excluding DNA as the main stress target in some cell types they propose alternatives to currently used and suggested synergistic treatment regimens.
authors.affiliation: Division of Toxicology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Birce
authors.initials: B
authors.lastname: Akpinar
authors.affiliation: Division of Toxicology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Ethiene V
authors.initials: EV
authors.lastname: Bracht
authors.affiliation: Division of Toxicology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Dorin
authors.initials: D
authors.lastname: Reijnders
authors.affiliation: Department of Cytokinetics, Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i., Brno, Czech Republic.
authors.forename: Barbora
authors.initials: B
authors.lastname: Safarikova
authors.affiliation: Department of Cytokinetics, Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i., Brno, Czech Republic.
authors.forename: Iva
authors.initials: I
authors.lastname: Jelinkova
authors.affiliation: Department of Medicine, Center for Infectious Medicine, Karolinska Institutet, Karolinska University Hospital-Huddinge, Stockholm, Sweden.
authors.forename: Alf
authors.initials: A
authors.lastname: Grandien
authors.affiliation: Division of Toxicology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.|Department of Cytokinetics, Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i., Brno, Czech Republic.
authors.forename: Alena Hyrslova
authors.initials: AH
authors.lastname: Vaculova
authors.affiliation: Division of Toxicology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Boris
authors.initials: B
authors.lastname: Zhivotovsky
authors.affiliation: Division of Toxicology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Magnus
authors.initials: M
authors.lastname: Olsson
mesh_terms: D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D045744:Cell Line, Tumor; D005455:Fluorescent Antibody Technique; D005472:Fluorouracil / Q000494:pharmacology*; D006801:Humans; D015151:Immunoblotting; D047468:Immunoprecipitation; D046529:Microscopy, Electron, Transmission; D016133:Polymerase Chain Reaction; D012313:RNA / Q000187:drug effects*; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000378:metabolism; D014161:Transduction, Genetic; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
chemical_list: D000964:Antimetabolites, Antineoplastic; D053221:TNF-Related Apoptosis-Inducing Ligand; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D012313:RNA; D005472:Fluorouracil
keywords: 5-fluorouracil; apoptosis; colon cancer; necrosis; p53