title: Resistance to APO-1 (CD95) induced apoptosis in T-ALL is determined by a BCL-2 independent anti-apoptotic program.
abstract: Selective induction of programmed cell death, apoptosis, may represent a new approach to the treatment of cancer. Apoptosis can be induced by the monoclonal antibody anti-APO-1 directed against the cell surface receptor APO-1, a member of the nerve growth factor (NGF) receptor/tumor necrosis factor (TNF) receptor superfamily. We determined APO-1 expression and sensitivity to anti-APO-1 mediated apoptosis in childhood acute lymphoblastic leukemia cells of T lymphocyte precursor phenotype (T-ALL). APO-1 was constitutively expressed by 21 of 30 T-ALL and by all T-ALL cell lines investigated. However, most APO-1 positive T-ALL were resistant to anti-APO-1 mediated apoptosis. Sensitivity to anti-APO-1 mediated apoptosis was independent of the density of APO-1 expression on the cell surface and independent of the amount of Bcl-2. Incubation of resistant T-ALL with the protein synthesis inhibitor cycloheximide reversed resistance and induced sensitivity to anti-APO-1 mediated apoptosis in most T-ALL. These data suggest that resistance to anti-APO-1 mediated apoptosis in T-ALL is maintained by an active cellular program. Reversion of resistance to sensitivity towards induction of apoptosis in tumors may provide a new basis for successful therapeutic intervention.
authors.affiliation: University Children's Hospital, Heidelberg, Germany.
authors.forename: K M
authors.initials: KM
authors.lastname: Debatin
authors.forename: P H
authors.initials: PH
authors.lastname: Krammer
mesh_terms: D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D000954:Antigens, Surface / Q000276:immunology* / Q000502:physiology; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D004351:Drug Resistance; D004354:Drug Screening Assays, Antitumor; D015870:Gene Expression; D006801:Humans; D015459:Leukemia-Lymphoma, Adult T-Cell / Q000378:metabolism / Q000473:pathology* / Q000628:therapy*; D009363:Neoplasm Proteins / Q000096:biosynthesis; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000378:metabolism / Q000473:pathology* / Q000628:therapy*; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000276:immunology; D014407:Tumor Cells, Cultured; D019014:fas Receptor
chemical_list: D000911:Antibodies, Monoclonal; D000954:Antigens, Surface; D009363:Neoplasm Proteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D011956:Receptors, Cell Surface; D019014:fas Receptor