title: Defective apoptotic signal transduction pathway downstream of caspase-3 in human B-lymphoma cells: A novel mechanism of nuclear apoptosis resistance.
abstract: Mitochondria play a central role in controlling apoptosis, and activation of the caspase cascade appears to be crucial event during the apoptotic process. Human B lymphoma Raji cells are resistant to nuclear apoptosis induced by various stimuli. Using this cell line, we have asked whether reduction of the mitochondrial transmembrane potential and activation of caspase-3 are sufficient to induce DNA fragmentation during the apoptotic process. After stimulation with cell-permeable C2-ceramide or mitochondrial permeability transition (PT) inducers, not only apoptosis-sensitive cell lines (HL-60, Jurkat, and Daudi cells), but also Raji cells showed reduction of the mitochondrial transmembrane potential (triangle uppsim), activation of caspase-3, and loss of clonogenic potential. However, Raji cells did not show detectable levels of nuclear apoptosis (DNA degradation). In a cell-free system, cell lysates from tetra-butylhydroperoxide (t-BHP)-treated HL-60 cells induced DNA degradation of Raji nuclei, whereas cell lysates from t-BHP-treated Raji cells failed to induce DNA degradation in either apoptosis-sensitive cell lines or apoptosis-resistant Raji cells. Cleavage of DFF-45, which is a downstream target molecule for caspase-3, was observed in Raji cells as well as in apoptosis-sensitive Daudi cells. These results indicate that there is a defective apoptotic pathway in the cytoplasm downstream of caspase-3 in Raji cells.
authors.affiliation: Department of Internal Medicine III, Akita University School of Medicine, Akita, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Kawabata
authors.forename: M
authors.initials: M
authors.lastname: Hirokawa
authors.forename: A
authors.initials: A
authors.lastname: Kitabayashi
authors.forename: T
authors.initials: T
authors.lastname: Horiuchi
authors.forename: J
authors.initials: J
authors.lastname: Kuroki
authors.forename: A B
authors.initials: AB
authors.lastname: Miura
mesh_terms: D000477:Alkylating Agents / Q000494:pharmacology; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism*; D002518:Ceramides / Q000494:pharmacology; D003600:Cytosol / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D053938:DNA Fragmentation; D004789:Enzyme Activation; D018922:HL-60 Cells; D006801:Humans; D020014:K562 Cells; D016393:Lymphoma, B-Cell / Q000201:enzymology* / Q000378:metabolism / Q000473:pathology; D008564:Membrane Potentials / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000502:physiology; D014176:Protein Biosynthesis; D011506:Proteins; D015398:Signal Transduction; D020298:U937 Cells; D020122:tert-Butylhydroperoxide / Q000494:pharmacology
chemical_list: D000477:Alkylating Agents; D051017:Apoptosis Regulatory Proteins; D002518:Ceramides; D011506:Proteins; C109664:caspase-activated DNase inhibitor; D004247:DNA; D020122:tert-Butylhydroperoxide; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases