Interferon-gamma sensitizes human myeloid leukemia cells to death receptor-mediated apoptosis by a pleiotropic mechanism.
The role of interferon (IFN)-gamma as a sensitizing agent in apoptosis induced by ligation of death receptors has been evaluated in human myeloid leukemia cells. Incubation of U937 cells with IFN-gamma sensitized these cells to apoptosis induced by tumor necrosis factor-alpha, agonistic CD95 antibody, and tumor necrosis factor-related apoptosis-inducing ligand. Other human myeloid leukemic cells were also sensitized by IFN-gamma to death receptor-mediated apoptosis. Treatment of U937 cells with IFN-gamma up-regulated the expression of caspase-8 and potently synergized with death receptor ligation in the processing of caspase-8 and BID cleavage. Concomitantly, a marked down-regulation of BCL-2 protein was also observed in cells incubated with IFN-gamma. Furthermore, the caspase-dependent generation of a 23-kDa fragment of BCL-2 protein, the release of cytochrome c from mitochondria and the activation of caspase-9 were also enhanced upon death receptor ligation in IFN-gamma-treated cells. Ectopically expressed Bcl-2 protein inhibited IFN-gamma-induced sensitization to apoptosis. In summary, these results indicate that IFN-gamma sensitizes human myeloid leukemic cells to a death receptor-induced, mitochondria-mediated pathway of apoptosis.
Varela
N
N
Instituto de Parasitologia y Biomedicina, Consejo Superior de Investigaciones Cientificas, calle Ventanilla 11, 18001 Granada, Spain.
Munoz-Pinedo
C
C
Ruiz-Ruiz
C
C
Robledo
G
G
Pedroso
M
M
López-Rivas
A
A
D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology*; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases / Q000502:physiology; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology*; D007951:Leukemia, Myeloid / Q000473:pathology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000502:physiology; D018124:Receptors, Tumor Necrosis Factor / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects; D020298:U937 Cells
D000970:Antineoplastic Agents; D019253:Proto-Oncogene Proteins c-bcl-2; D018124:Receptors, Tumor Necrosis Factor; D007371:Interferon-gamma; C505530:CASP8 protein, human; C506433:CASP9 protein, human; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases