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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, Karina G
Seidinger, Ana Luiza O
Chiaratti, Marcos R
Degasperi, Giovanna R
Meirelles, Flávio V
Castilho, Roger F
Vercesi, Aníbal E
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 Ca(2+). In the present study, we analyze H(2)O(2)-induced apoptotic death in two different types of tumor cells: Walker 256 and SCC-25. Treatment with H(2)O(2) (4mM) increased reactive oxygen species generation and the concentration of cytosolic free Ca(2+). 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 (DeltaPsi(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 DeltaPsi(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: Animals
Carcinoma 256, Walker
Caspase 3
Cell Line, Tumor
Cytochromes C
Hydrogen Peroxide
Membrane Potential, Mitochondrial
Oxidative Stress
Proto-oncogene Proteins C-bcl-2
Rats, Wistar
Reactive Oxygen Species
Signal Transduction
Bcl-2-associated X Protein
Citation: Journal Of Bioenergetics And Biomembranes. v. 39, n. 2, p. 186-94, 2007-Apr.
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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