title: TRAIL enhances thymidine kinase/ganciclovir gene therapy of neuroblastoma cells.
abstract: The clinical benefit of suicide gene therapy of tumors has been marginal, mostly due to the low gene transfer efficiency in vivo. The death-inducing ligand, TRAIL, effectively kills many tumor cell types, while sparing most normal tissues. We hypothesized that TRAIL may enhance HSV thymidine kinase/ganciclovir (TK/GCV) gene therapy of tumor cells by augmenting both target and bystander cell kill. Human SH-EP neuroblastoma cells expressing TK as well as bystander cells were effectively killed by apoptosis, and their clonogenicity was ablated following GCV. Human TRAIL enhanced TK/GCV-induced cell death and decreased clonogenicity of TK-expressing cells and also of bystander cells. Cooperation between TRAIL and TK/GCV depended both on caspase activation and on mitochondrial apoptogenic function because both the broad-spectrum caspase inhibitor zVAD.fmk and overexpression of Bcl-2 decreased enhancement of cell kill by TRAIL. Facilitation of TRAIL signalling by up-regulation of TRAIL receptors did not contribute to enhancement because cell surface expression of the agonistic TRAIL receptors 1 and 2 was not increased by TK/GCV. In conclusion, the concerted activation of caspases and the mitochondrial amplification of caspase activation by TK/GCV may explain the cooperative effect of TK/GCV and TRAIL on the kill of neuroblastoma cells. Because combined treatment also augmented the bystander cell kill, the addition of TRAIL may increase the efficacy of TK/GCV gene therapy of neuroblastoma.
authors.affiliation: University Children's Hospital, Ulm 89075, Germany. christian.beltinger@medizin.uni-ulm.de
authors.forename: Christian
authors.initials: C
authors.lastname: Beltinger
authors.forename: Simone
authors.initials: S
authors.lastname: Fulda
authors.forename: Henning
authors.initials: H
authors.lastname: Walczak
authors.forename: Klaus-Michael
authors.initials: KM
authors.lastname: Debatin
mesh_terms: D000256:Adenoviridae / Q000235:genetics*; D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000998:Antiviral Agents / Q000627:therapeutic use*; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D003114:Colony-Forming Units Assay; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D003574:Cytochrome c Group / Q000378:metabolism*; D004789:Enzyme Activation; D015774:Ganciclovir / Q000627:therapeutic use*; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors / Q000008:administration & dosage; D018259:Herpesvirus 1, Human / Q000201:enzymology; D006801:Humans; D008562:Membrane Glycoproteins / Q000502:physiology*; D009447:Neuroblastoma / Q000628:therapy*; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism; D053221:TNF-Related Apoptosis-Inducing Ligand; D013778:Tetrazolium Salts; D013844:Thiazoles; D013937:Thymidine Kinase / Q000235:genetics* / Q000378:metabolism; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology*
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D000998:Antiviral Agents; D051017:Apoptosis Regulatory Proteins; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D003574:Cytochrome c Group; D008562:Membrane Glycoproteins; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor; D053221:TNF-Related Apoptosis-Inducing Ligand; C105190:TNFRSF10A protein, human; C505639:TNFRSF10B protein, human; C505653:TNFSF10 protein, human; D013778:Tetrazolium Salts; D013844:Thiazoles; D014409:Tumor Necrosis Factor-alpha; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D013937:Thymidine Kinase; D020169:Caspases; C022616:thiazolyl blue; D015774:Ganciclovir