title: Death of HT29 adenocarcinoma cells induced by TNF family receptor activation is caspase-independent and displays features of both apoptosis and necrosis.
abstract: The HT29 adenocarcinoma is a common model of epithelial cell differentiation and colorectal cancer and its death is an oft-analyzed response to TNF family receptor signaling. The death event itself remains poorly characterized and here we have examined the involvement of caspases using pan-caspase inhibitors. zVAD-fmk did not block death of HT29 cells in response to activation of the Fas, TRAIL, TNF, TWEAK and LTbeta receptors. The secondary induction of TNF or the other known bona fide death inducing ligands did not account for death following LTbeta receptor activation indicating that TNF family receptors can trigger a caspase-independent death pathway regardless of the presence of canonical death domains in the receptor. To provide a frame of reference, the phenotype of HT29 death was compared to four other TNF family receptor triggered death events; Fas induced Jurkat cell apoptosis, TNF/zVAD induced L929 fibroblast necrosis, TNF induced death of WEHI 164 fibroblastoid cells and TNF/zVAD induced U937 death. The death of HT29 and U937 cells under these conditions is an intermediate form with both necrotic and apoptotic features. The efficient coupling of TNF receptors to a caspase-independent death event in an epithelial cell suggests an alternative approach to cancer therapy.
authors.affiliation: Department of Exploratory Biology, Biogen, 12 Cambridge Center, Cambridge, MA 02142, USA.
authors.forename: C A
authors.initials: CA
authors.lastname: Wilson
authors.forename: J L
authors.initials: JL
authors.lastname: Browning
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000187:drug effects / Q000235:genetics; D000230:Adenocarcinoma / Q000188:drug therapy / Q000201:enzymology* / Q000235:genetics; D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism*; D015179:Colorectal Neoplasms / Q000188:drug therapy / Q000201:enzymology* / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects / Q000201:enzymology* / Q000648:ultrastructure; D006801:Humans; D053259:Lymphotoxin beta Receptor; D051379:Mice; D008854:Microscopy, Electron; D008928:Mitochondria / Q000187:drug effects / Q000201:enzymology; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor / Q000187:drug effects / Q000378:metabolism*; D000074050:TWEAK Receptor; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000201:enzymology / Q000648:ultrastructure; D019014:fas Receptor / Q000187:drug effects / Q000378:metabolism
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D061945:Caspase Inhibitors; D004791:Enzyme Inhibitors; C505697:LTBR protein, human; C505699:Ltbr protein, mouse; D053259:Lymphotoxin beta Receptor; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor; C105190:TNFRSF10A protein, human; D000074050:TWEAK Receptor; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D019014:fas Receptor; D020169:Caspases