Mechanisms of JP-8 jet fuel toxicity. I. Induction of apoptosis in rat lung epithelial cells.
JP-8 is a kerosene-based fuel widely used by the U.S. military. Various models of human occupational and animal exposure to JP-8 have demonstrated the potential for local and systemic toxicity but the mechanisms involved are unknown. The purpose of our investigation was to study the molecular mechanisms of JP-8 toxicity by using an in vitro model. JP-8 exposure in a rat lung alveolar type II epithelial cell line (RLE-6TN) induces biochemical and morphological markers of apoptotic cell death: caspase-3 activation, poly(ADP-ribose) polymerase (PARP) cleavage, chromatin condensation, membrane blebbing, cytochrome c release from mitochondria, and genomic DNA cleavage into both oligonucleosomal (DNA ladder) and high-molecular-weight (HMW) fragments. The human histiocytic lymphoma cell line (U937) also responds to JP-8 with caspase-3 activation, cleavage of caspase substrates, including PARP, DNA-PK, and lamin B1, and degradation of genomic DNA with the production of HMW fragments. Caspase-3 activation and PARP cleavage also occur in the acute T-cell leukemia cell line (Jurkat) following treatment with JP-8. Furthermore, Jurkat cells stably transfected with a plasmid encoding the antiapoptotic protein Bcl-x(L) or pretreated with the pan-caspase inhibitor Boc-d-fmk, are relatively resistant to the cytotoxic effects of JP-8 compared to control cells. Finally, we demonstrate that PARP cleavage occurs in primary mouse thymocytes exposed to JP-8. In conclusion, our data support the hypothesis that apoptotic cell death is responsible at least partially for the cytotoxic effects of JP-8 and suggest that inhibition of the apoptotic cascade might reduce JP-8 toxicity.
Stoica
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BA
Department of Biochemistry and Molecular Biology, Georgetown University School of Medicine, Washington, D.C. 20007, USA.
Boulares
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Rosenthal
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Iyer
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Hamilton
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Smulson
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D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000473:pathology; D002843:Chromatin / Q000648:ultrastructure; D003574:Cytochrome c Group / Q000378:metabolism; D053938:DNA Fragmentation; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000473:pathology; D006801:Humans; D006838:Hydrocarbons / Q000008:administration & dosage / Q000633:toxicity*; D019169:Jurkat Cells; D008168:Lung / Q000473:pathology*; D016403:Lymphoma, Large B-Cell, Diffuse / Q000473:pathology; D051379:Mice; D009000:Monocytes / Q000473:pathology; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000502:physiology; D011650:Pulmonary Alveoli / Q000187:drug effects / Q000473:pathology; D051381:Rats; D014162:Transfection; D014407:Tumor Cells, Cultured; D051020:bcl-X Protein
C494811:BCL2L1 protein, human; C494812:Bcl2l1 protein, mouse; C494813:Bcl2l1 protein, rat; D061945:Caspase Inhibitors; D002843:Chromatin; D003574:Cytochrome c Group; D004791:Enzyme Inhibitors; D006838:Hydrocarbons; C098607:JP8 aviation fuel; D019253:Proto-Oncogene Proteins c-bcl-2; D051020:bcl-X Protein; D011065:Poly(ADP-ribose) Polymerases; C505407:CASP3 protein, human; C505409:Casp3 protein, mouse; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases