title: Crocidolite asbestos induces apoptosis of pleural mesothelial cells: role of reactive oxygen species and poly(ADP-ribosyl) polymerase.
abstract: Mesothelial cells, the progenitor cells of the asbestos-induced tumor mesothelioma, are particularly sensitive to the toxic effects of asbestos, although the molecular mechanisms by which asbestos induces injury in mesothelial cells are not known. We asked whether asbestos induced apoptosis in mesothelial cells and whether reactive oxygen species were important. Rabbit pleural mesothelial cells were exposed to crocidolite asbestos or control particles (1-10 micrograms/cm2) over 24 hr and evaluated for oligonucleosomal DNA fragmentation, loss of membrane phospholipid asymmetry, and nuclear condensation. Asbestos fibers, not control particles, induced apoptosis in mesothelial cells by all assays. Induction of apoptosis was dose dependent; crocidolite (5 micrograms/cm2) induced apoptosis (15.0 +/- 1.1%, mean +/- SE; n = 12) versus control particles (< 4%), as measured by appearance of nuclear condensation. Apoptosis induced by asbestos, but not by actinomycin D, was inhibited by extracellular catalase, superoxide dismutase in the presence of catalase, hypoxia (8% oxygen), deferoxamine, and 3-aminobenzamide (an inhibitor of the nuclear enzyme, poly(adenosine diphosphate-ribosyl) polymerase). We conclude that asbestos induces apoptosis in mesothelial cells via reactive oxygen species. We speculate that escape from this pathway could allow the abnormal survival of mesothelial cells with asbestos-induced mutations.
authors.affiliation: Lung Biology Center, University of California, San Francisco General Hospital 94143-0854, USA. sfcourt@itsa.ucsf.edu
authors.forename: V C
authors.initials: VC
authors.lastname: Broaddus
authors.forename: L
authors.initials: L
authors.lastname: Yang
authors.forename: L M
authors.initials: LM
authors.lastname: Scavo
authors.forename: J D
authors.initials: JD
authors.lastname: Ernst
authors.forename: A M
authors.initials: AM
authors.lastname: Boylan
mesh_terms: D000818:Animals; D017304:Annexin A5 / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects*; D017638:Asbestos, Crocidolite / Q000633:toxicity*; D002273:Carcinogens / Q000633:toxicity*; D002374:Catalase / Q000378:metabolism; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D053938:DNA Fragmentation / Q000187:drug effects; D003676:Deferoxamine / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D007502:Iron Chelating Agents / Q000494:pharmacology; D008563:Membrane Lipids / Q000378:metabolism; D010994:Pleura / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism*; D011817:Rabbits; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D017304:Annexin A5; D002273:Carcinogens; D007502:Iron Chelating Agents; D008563:Membrane Lipids; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D017382:Reactive Oxygen Species; D017638:Asbestos, Crocidolite; D002374:Catalase; D013482:Superoxide Dismutase; D011065:Poly(ADP-ribose) Polymerases; D003676:Deferoxamine