| Mechanisms involved in the induction of apoptosis by T-2 and HT-2 toxins in HL-60 human promyelocytic leukemia cells. | |
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MedLine Citation:
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PMID: 12661987 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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T-2 and HT-2 toxins belong to a group of mycotoxins that are widely encountered as natural contaminants known to elicit toxic responses in hematopoietic cells. In the present study, HL-60 cells were used to characterize the apoptotic effects of T-2 and a major metabolite, HT-2, and to examine the mechanisms involved. Apoptotic cells were identified microscopically by chromatin condensation and nuclear fragmentation, by flow cytometric analysis, and by DNA gel electrophoresis. T-2 and HT-2 induced concentration-dependent apoptosis after 24 h in HL-60 cells, starting at concentrations of 3.1 and 6.25 ng/ml respectively. An increased number of apoptotic cells could be observed 4-6 h after exposure to 12.5 ng/ml of toxin. Little cytotoxicity (plasma membrane damage) was observed even after exposure to concentrations of toxins (25-50 ng/ml) inducing apoptosis in 60-100% of the cells. The apoptotic process was almost completely blocked in the presence of the general caspase inhibitor zVAD.fmk. In contrast, no or only minor effects were observed with the more specific caspase inhibitors DEVD.CHO, IETD.fmk, and DEVD.fmk. As judged by Western blotting, the levels of several procaspases (-3, -7, -8, -9, but not -12) were reduced 3-6 h after exposure to toxin. Substantial increases in the presumed active form(s) of caspase-8 and -9 were observed. Furthermore, poly(ADP-ribose) polymerase (PARP) was already markedly cleaved 3 h after toxin treatment, indicative of active caspase-3 and -7. No or only minor changes in Bcl-2, Bcl-XL and Bax levels were observed. BAPTA-AM and ZnCl2 blocked the degradation of procaspases, the fragmentation of PARP, and the induction of apoptosis. In summary, both T-2 and HT-2 induced apoptosis, with T-2 being somewhat more potent than HT-2. The divalent calcium concentration, [Ca2+], appears to be involved in the activation of several caspases, resulting in DNA fragmentation, chromosomal condensation, and nuclear fragmentation. |
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Authors:
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J A Holme; E Morrison; J T Samuelsen; R Wiger; M Låg; P E Schwarze; A Bernhoft; M Refsnes |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Cell biology and toxicology Volume: 19 ISSN: 0742-2091 ISO Abbreviation: Cell Biol. Toxicol. Publication Date: 2003 Feb |
Date Detail:
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Created Date: 2003-03-28 Completed Date: 2003-09-17 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 8506639 Medline TA: Cell Biol Toxicol Country: Netherlands |
Other Details:
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Languages: eng Pagination: 53-68 Citation Subset: IM |
Affiliation:
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Division of Environmental Medicine, Norwegian Institute of Public Health, Nydalen, Oslo, Norway. jorn.holme@fhi.no |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Apoptosis
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drug effects* Blotting, Western Caspases / biosynthesis DNA Fragmentation / drug effects Flow Cytometry HL-60 Cells Humans Leukemia, Promyelocytic, Acute / pathology Proto-Oncogene Proteins / biosynthesis Proto-Oncogene Proteins c-bcl-2 / biosynthesis T-2 Toxin / analogs & derivatives*, toxicity* bcl-2-Associated X Protein bcl-X Protein |
| Chemical | |
Reg. No./Substance:
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0/BAX protein, human; 0/BCL2L1 protein, human; 0/Proto-Oncogene Proteins; 0/Proto-Oncogene Proteins c-bcl-2; 0/bcl-2-Associated X Protein; 0/bcl-X Protein; 21259-20-1/T-2 Toxin; 26934-87-2/HT-2 toxin; EC 3.4.22.-/Caspases |
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