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Type: Artigo de periódico
Title: High Bcl-2/Bax ratio in Walker tumor cells protects mitochondria but does not prevent H2O2-induced apoptosis via calcineurin pathways
Author: Zecchin, KG
Seidinger, ALO
Chiaratti, MR
Degasperi, GR
Meirelles, FV
Castilho, RF
Vercesi, AE
Abstract: It has been previously shown that Walker 256 tumor cells express a high content of the anti-apoptotic protein Bcl-2 which protects mitochondria against the damaging effects of Ca2+. In the present study, we analyze H2O2-induced apoptotic death in two different types of tumor cells: Walker 256 and SCC-25. Treatment with H2O2 (4mM) increased reactive oxygen species generation and the concentration of cytosolic free Ca2+. These alterations preceded apoptosis in both cell lines. In Walker cells, which show a high Bcl-2/Bax ratio, apoptosis was dependent on calcineurin activation and independent of changes in mitochondrial membrane potential (Delta psi(m)), as well as cytochrome c release. In contrast, in SCC-25 cells, which show a lower Bcl-2/Bax ratio, apoptosis was preceded by a decrease in Delta psi(m), mitochondrial permeability transition, and cytochrome c release. Caspase-3 activation occurred in both cell lines. The data suggest that although the high Bcl-2/Bax ratio protected the mitochondria of Walker cells from oxidative stress, it was not sufficient to prevent apoptosis through calcineurin pathways.
Subject: Bcl-2/Bax ratio
calcium homeostasis
oxidative stress
mitochondrial permeability transition
Country: EUA
Editor: Springer/plenum Publishers
Citation: Journal Of Bioenergetics And Biomembranes. Springer/plenum Publishers, v. 39, n. 2, n. 186, n. 194, 2007.
Rights: fechado
Identifier DOI: 10.1007/s10863-007-9076-z
Date Issue: 2007
Appears in Collections:Unicamp - Artigos e Outros Documentos

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