title: Induction of necrotic tumor cell death by TRAIL/Apo-2L.
abstract: A great deal of enthusiasm is being generated for TRAIL (TNF-related apoptosis-inducing ligand)/Apo-2L as a tumor therapeutic agent because it is cytotoxic to a variety of tumor cell types but not normal cells. Moreover, it is well documented that TRAIL/Apo-2L-induced tumor cell death is a caspase-dependent apoptotic process. Through the use of a transfected cell line expressing murine TRAIL/Apo-2L and a recombinant adenovirus encoding the murine TRAIL/Apo-2L cDNA (Ad5-mTRAIL) against two murine tumor cell lines [TRAMP-C2 (prostate adenocarcinoma) and Renca (renal adenocarcinoma)], we found that mTRAIL/Apo-2L also can kill tumor cells by inducing necrosis. Specifically, we observed the default method of mTRAIL/Apo-2L-induced death in TRAMP-C2 cells was via a necrotic process, characterized by the complete lack of an annexin V(+)/PI(-) population, SAPK/JNK phosphorylation, caspase activation, Bid cleavage, or cytochrome c release. Moreover, the inclusion of zVAD-fmk, an inhibitor of caspase activation, markedly enhanced mTRAIL/Apo-2L-mediated killing of TRAMP-C2. In contrast, apoptosis was induced in TRAMP-C2 using TNF, as measured by the criteria listed above, as was Renca by mTRAIL/Apo-2L. These results demonstrate the natural occurrence of both TRAIL/Apo-2L-induced apoptotic and necrotic signaling mechanisms within tumor cells.
authors.affiliation: Department of Urology, Interdisciplinary Graduate Program in Immunology, University of Iowa, Iowa City, IA 52242-1089, USA.
authors.forename: T J
authors.initials: TJ
authors.lastname: Kemp
authors.forename: J-S
authors.initials: JS
authors.lastname: Kim
authors.forename: S A
authors.initials: SA
authors.lastname: Crist
authors.forename: T S
authors.initials: TS
authors.lastname: Griffith
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008854:Microscopy, Electron; D053221:TNF-Related Apoptosis-Inducing Ligand; D014162:Transfection; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism*
chemical_list: D051017:Apoptosis Regulatory Proteins; D008562:Membrane Glycoproteins; D053221:TNF-Related Apoptosis-Inducing Ligand; C505654:Tnfsf10 protein, mouse; D014409:Tumor Necrosis Factor-alpha