title: Inhibition of tumor necrosis factor alpha- and ceramide-induced internucleosomal DNA fragmentation by herbimycin A in U937 cells.
abstract: In many tumor cell lines, tumor necrosis factor alpha (TNF alpha) causes apoptosis with characteristic internucleosomal DNA fragmentation. However, the mechanism is largely unknown. Here we examined the involvement of protein tyrosine kinases by using their inhibitors. Among various tyrosine kinase inhibitors tested, only herbimycin A was found to inhibit internucleosomal DNA fragmentation but not apoptotic morphological changes and cell death induced by TNF alpha in U937 cells. Herbimycin A was able to block DNA fragmentation when it was added to the cell culture as late as 1.5 h after TNF alpha treatment. These results demonstrate that herbimycin A selectively inhibits a later event involved in the process of apoptois that results in internucleosomal DNA fragmentation. Sphingomyelinase and ceramide (Cer) induced internucleosomal DNA fragmentation was also inhibited by herbimycin A, supporting the hypothesis that Cer may be a novel second messenger mediating the cytotoxic effect of TNF alpha.
authors.affiliation: Laboratory for Glyco Cell Biology, Institute of Chemical and Physical Research (Riken), Saitama, Japan.
authors.forename: L
authors.initials: L
authors.lastname: Ji
authors.forename: G
authors.initials: G
authors.lastname: Zhang
authors.forename: Y
authors.initials: Y
authors.lastname: Hirabayashi
mesh_terms: D017209:Apoptosis; D016227:Benzoquinones; D002518:Ceramides / Q000494:pharmacology*; D004247:DNA / Q000378:metabolism*; D006801:Humans; D047029:Lactams, Macrocyclic; D009707:Nucleosomes / Q000378:metabolism*; D010766:Phosphorylation; D019000:Phosphotyrosine; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D011809:Quinones / Q000494:pharmacology*; D017828:Rifabutin / Q000031:analogs & derivatives; D015290:Second Messenger Systems; D015398:Signal Transduction; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
chemical_list: D016227:Benzoquinones; D002518:Ceramides; D047029:Lactams, Macrocyclic; D009707:Nucleosomes; D011809:Quinones; D014409:Tumor Necrosis Factor-alpha; D017828:Rifabutin; D019000:Phosphotyrosine; D014443:Tyrosine; C020754:herbimycin; D004247:DNA; D011505:Protein-Tyrosine Kinases