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High Bcl-2/Bax ratio in Walker tumor cells protects mitochondria but does not prevent H2O2-induced apoptosis via calcineurin pathways.
Zecchin, Karina G; Seidinger, Ana Luiza O; Chiaratti, Marcos R; Degasperi, Giovanna R; Meirelles, Flávio V; Castilho, Roger F; Vercesi, Aníbal E.
Afiliação
  • Zecchin KG; Departamento de Patologia Clínica, Faculdade de Ciências Médicas, Universidade Estadual de Campinas (UNICAMP), Campinas, SP 13083-887, Brazil.
J Bioenerg Biomembr ; 39(2): 186-94, 2007 Apr.
Article em En | MEDLINE | ID: mdl-17431754
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.
Assuntos
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Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Apoptose / Proteínas Proto-Oncogênicas c-bcl-2 / Calcineurina / Peróxido de Hidrogênio / Mitocôndrias Limite: Animals / Humans / Male Idioma: En Revista: J Bioenerg Biomembr Ano de publicação: 2007 Tipo de documento: Article País de afiliação: Brasil País de publicação: Estados Unidos
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Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Apoptose / Proteínas Proto-Oncogênicas c-bcl-2 / Calcineurina / Peróxido de Hidrogênio / Mitocôndrias Limite: Animals / Humans / Male Idioma: En Revista: J Bioenerg Biomembr Ano de publicação: 2007 Tipo de documento: Article País de afiliação: Brasil País de publicação: Estados Unidos