title: Multiple mechanisms underlie resistance of leukemia cells to Apo2 Ligand/TRAIL.
abstract: Targeting death receptors with tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has the remarkable potential to selectively kill malignant cells whereas normal cells are largely unaffected by this treatment. However, some tumor cells, including leukemia cells, exhibit resistance to this molecule. To investigate the basis for resistance of leukemia cells to the zinc-bound form of Apo2 ligand (Apo2L)/TRAIL, which is currently being evaluated in clinical trial, we isolated several resistant HL60 clones from parental HL60 cells by selection using the recombinant Apo2L/TRAIL. Differing resistance mechanisms were identified and characterized in these Apo2L/TRAIL-resistant clones. In one case, the level of the cell-surface death receptor DR4, but not DR5, was significantly decreased. However, these cells did undergo apoptosis in response to another form of recombinant TRAIL, histidine-tagged TRAIL, suggesting differing contributions of DR4 and DR5 in the response to these two forms of TRAIL. In the case of other clones, expression of procaspase-8 protein was lost and this was associated with a novel Leu(22)-->Phe(22) point mutation in CASP-8 gene. These results show that cells within a given tumor can have widely distinct mechanisms underlying resistance to Apo2L/TRAIL.
authors.affiliation: Department of Immunology, Roswell Park Cancer Institute, Elm and Carlton Streets, Buffalo, NY 14263, USA.
authors.forename: Jinrong
authors.initials: J
authors.lastname: Cheng
authors.forename: Bonnie L
authors.initials: BL
authors.lastname: Hylander
authors.forename: Maria R
authors.initials: MR
authors.lastname: Baer
authors.forename: Xing
authors.initials: X
authors.lastname: Chen
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Repasky
mesh_terms: D019943:Amino Acid Substitution; D051017:Apoptosis Regulatory Proteins / Q000627:therapeutic use*; D053181:Caspase 8; D020169:Caspases / Q000172:deficiency* / Q000235:genetics; D002462:Cell Membrane / Q000737:chemistry; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D018922:HL-60 Cells; D006801:Humans; D015473:Leukemia, Promyelocytic, Acute / Q000188:drug therapy*; D008562:Membrane Glycoproteins / Q000627:therapeutic use*; D017354:Point Mutation; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor / Q000032:analysis / Q000172:deficiency* / Q000378:metabolism; D053221:TNF-Related Apoptosis-Inducing Ligand; D014409:Tumor Necrosis Factor-alpha / Q000627:therapeutic use*
chemical_list: D051017:Apoptosis Regulatory Proteins; 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; D014409:Tumor Necrosis Factor-alpha; C505530:CASP8 protein, human; D053181:Caspase 8; D020169:Caspases