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- Alleva, R., et al.
(författare)
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Coenzyme Q blocks biochemical but not receptor-mediated apoptosis by increasing mitochondrial antioxidant protection
- 2001
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Ingår i: FEBS Letters. - 0014-5793 .- 1873-3468. ; 503:1, s. 46-50
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Tidskriftsartikel (refereegranskat)abstract
- Generation of free radicals is often associated with the induction and progression of apoptosis. Therefore, antioxidants can prove anti-apoptotic, and can help to elucidate specific apoptotic pathways. Here we studied whether coenzyme Q, present in membranes in reduced (ubiquinol) or oxidised (ubiquinone) forms, can affect apoptosis induced by various stimuli. Exposure of Jurkat cells to a-tocopheryl succinate (a-TOS), hydrogen peroxide, anti-Fas IgM or TRAIL led to induction of apoptosis. Cell death due to the chemical agents was suppressed in cells enriched with the reduced form of coenzyme Q. However, coenzyme Q did not block cell death induced by the immunological agents. Ubiquinol-10 inhibited reactive oxygen species (ROS) generation in cells exposed to a-TOS, and a mitochondrially targeted coenzyme Q analogue also blocked apoptosis triggered by a-TOS or hydrogen peroxide. Therefore, it is plausible that ubiquinol-10 protects cells from chemically-induced apoptosis by acting as an antioxidant in mitochondria. Our results also indicate that generation of free radicals may not be a critical step in induction of apoptosis by immunological agents. © 2001 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.
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| 2. |
- Weber, A, et al.
(författare)
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Mitochondria play a central role in apoptosis induced by a-tocopheryl succinate, an agent with antineoplastic activity : Comparison with receptor-mediated pro-apoptotic signaling
- 2003
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Ingår i: Biochemistry. - : American Chemical Society (ACS). - 0006-2960 .- 1520-4995. ; 42:14, s. 4277-4291
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Tidskriftsartikel (refereegranskat)abstract
- a-Tocopheryl succinate (a-TOS) is a semisynthetic vitamin E analogue with high pro-apoptotic and anti-neoplastic activity [Weber, T et al. (2002) Clin. Cancer Res. 8, 863-869]. Previous studies suggested that it acts through destabilization of subcellular organelles, including mitochondria, but compelling evidence is missing. Cells treated with a-TOS showed altered mitochondrial structure, generation of free radicals, activation of the sphingomyelin cycle, relocalization of cytochrome c and Smac/Diablo, and activation of multiple caspases. A pan-caspase inhibitor suppressed caspase-3 and -6 activation and phosphatidyl serine externalization, but not decrease of mitochondrial membrane potential or generation of radicals. For a-TOS, but not Fas or TRAIL, apoptosis was suppressed by caspase-9 inhibition, while TRAIL- and Fas-resistant cells overexpressing cFLIP or CrmA were susceptible to a-TOS. The central role of mitochondria was confirmed by resistance of mtDNA-deficient cells to a-TOS, by regulation of a-TOS apoptosis by Bcl-2 family members, and by anti-apoptotic activity of mitochondrially targeted radical scavengers. Co-treatment with a-TOS and anti-Fas IgM showed their cooperative effect, probably by signaling via different, convergent pathways. These data provide an insight into the molecular mechanism, by which a-TOS kills malignant cells, and advocate its testing as a potential anticancer agent or adjuvant.
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