12471614

pubmed:Citation

3

Exogenous beta(2)-microglobulin (beta(2)m) induces significant apoptosis in the CCRF-HSB-2 human lymphoblastic leukemia cell line as detected by DNA fragmentation, DAPI staining and annexin V binding assay. beta(2)m treatment induced the release of cytochrome c and apoptosis-inducing factor (AIF) from the mitochondria, but no change in mitochondrial membrane potential (DeltaPsim) was observed during apoptosis, suggesting that cytochrome c may be released through a mechanism independent of mitochondrial permeability transition (MPT) pore formation. Moreover, the beta(2)m-induced release of cytochrome c and AIF from the mitochondria in CCRF-HSB-2 cells was caspase-independent, since Z-VAD-fmk, a general inhibitor of caspases, did not block the release of these factors. However, Z-VAD-fmk treatment significantly blocked beta(2)m-induced apoptosis, while Western blot analysis revealed that caspases-1, -2, -3, -6, -7, -8 and -9 are not activated during beta(2)m-induced apoptosis in these cells. These results collectively indicate that a post-mitochondrial caspase-dependent mechanism is involved in beta(2)m-induced apoptosis. Moreover, beta(2)m significantly enhanced the production of reactive oxygen species (ROS) during 12-48 hr treatment, and beta(2)m-induced apoptosis was almost totally inhibited in cells pre-treated with the antioxidant N-acetylcysteine (NAC), providing evidence that beta(2)m-induced apoptosis in CCRF-HSB-2 cells is ROS-dependent. Therefore, these results reveal that beta(2)m-induced apoptosis in CCRF-HSB-2 cells may occur through an unknown caspase-dependent and ROS-dependent mechanism(s) that is associated with cytochrome c and AIF release from mitochondria, but is independent of the caspase -3, -8 and -9 pathways.

eng

IM

MEDLINE

0020-7136

Copyright 2002 Wiley-Liss, Inc.

20

NLM

316-27

pubmed-meshheading:12471614-Annexin A5, pubmed-meshheading:12471614-Apoptosis, pubmed-meshheading:12471614-Apoptosis Inducing Factor, pubmed-meshheading:12471614-Blotting, Western, pubmed-meshheading:12471614-Caspases, pubmed-meshheading:12471614-Cytochrome c Group, pubmed-meshheading:12471614-Enzyme Inhibitors, pubmed-meshheading:12471614-Enzyme-Linked Immunosorbent Assay, pubmed-meshheading:12471614-Flavoproteins, pubmed-meshheading:12471614-Flow Cytometry, pubmed-meshheading:12471614-HLA Antigens, pubmed-meshheading:12471614-Humans, pubmed-meshheading:12471614-Leukemia-Lymphoma, Adult T-Cell, pubmed-meshheading:12471614-Membrane Potentials, pubmed-meshheading:12471614-Membrane Proteins, pubmed-meshheading:12471614-Poly(ADP-ribose) Polymerases, pubmed-meshheading:12471614-Reactive Oxygen Species, pubmed-meshheading:12471614-Tumor Cells, Cultured, pubmed-meshheading:12471614-beta 2-Microglobulin

Beta2-microglobulin induces caspase-dependent apoptosis in the CCRF-HSB-2 human leukemia cell line independently of the caspase-3, -8 and -9 pathways but through increased reactive oxygen species.

Journal Article, Research Support, U.S. Gov't, P.H.S.