title: Requirement for caspase activation in monocytic differentiation of myeloid leukemia cells.
abstract: Human myeloid leukemia cells respond to 12-tetradecanoylphorbol-13-acetate (TPA) and other activators of protein kinase C (PKC) with the induction of terminal monocytic differentiation. The present studies demonstrate that TPA treatment of U-937 leukemia cells is associated with release of mitochondrial cytochrome c, activation of caspase-3 and induction of internucleosomal DNA fragmentation. By contrast, the TUR cell variant, which is deficient in PKCbeta, failed to respond to TPA with release of cytochrome c and induction of the caspase-3 cascade. Moreover, stable overexpression of PKCbeta in TUR cells reconstituted sensitivity to TPA-induced cytochrome c release and activation of caspase-3. The results also demonstrate that treatment of cells with the caspase inhibitor Z-VAD-fmk blocks both TPA-induced apoptosis and monocytic differentiation. Similar results were obtained in U-937 cells stably expressing the CrmA caspase inhibitor. These findings demonstrate that TPA induces cytochrome c release by a PKCbeta-dependent mechanism and that activation of caspase-mediated signaling is required for induction of the differentiated monocytic phenotype.
authors.affiliation: Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02115, USA.
authors.forename: P
authors.initials: P
authors.lastname: Pandey
authors.forename: A
authors.initials: A
authors.lastname: Nakazawa
authors.forename: Y
authors.initials: Y
authors.lastname: Ito
authors.forename: R
authors.initials: R
authors.lastname: Datta
authors.forename: S
authors.initials: S
authors.lastname: Kharbanda
authors.forename: D
authors.initials: D
authors.lastname: Kufe
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D020170:Caspase 1 / Q000378:metabolism; D053148:Caspase 3; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism*; D002454:Cell Differentiation / Q000187:drug effects; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D003574:Cytochrome c Group / Q000187:drug effects / Q000378:metabolism; D004789:Enzyme Activation; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D007951:Leukemia, Myeloid / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology*; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism; D064546:Protein Kinase C beta; D015843:Serpins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D014764:Viral Proteins
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D003574:Cytochrome c Group; D007527:Isoenzymes; D015843:Serpins; D014764:Viral Proteins; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; C074641:interleukin-1beta-converting enzyme inhibitor; D011493:Protein Kinase C; D064546:Protein Kinase C beta; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D020170:Caspase 1; D013755:Tetradecanoylphorbol Acetate