Caspase-3 activation by lysosomal enzymes in cytochrome c-independent apoptosis in myelodysplastic syndrome-derived cell line P39.
Cancer Res
; 61(7): 2878-84, 2001 Apr 01.
Article
em En
| MEDLINE
| ID: mdl-11306462
ABSTRACT
In most cases, apoptosis is considered to involve mitochondrial dysfunction with sequential release of cytochrome c from mitochondria, resulting in activation of caspase-3. However, we found that etoposide induced apoptosis in P39 cells, a myelodysplastic syndrome-derived cell line, without the release of cytochrome c. Furthermore, in etoposide-treated P39 cells, no changes in mitochondrial membrane potential (delta psi m) were detected by flow cytometry. Flow cytometry using a pH-sensitive probe demonstrated that lysosomal pH increased during early apoptosis in P39 cells treated with etoposide. A reduction in the ATP level preceded the elevation of lysosomal pH. In addition, specific inhibitors of vacuolar H+-ATPase induced apoptosis in P39 cells but not in HL60 cells. Although etoposide-induced activation of caspase-3 was followed by DNA ladder formation in P39 cells, E-64d, an inhibitor of lysosomal thiol proteases, specifically suppressed etoposide-induced activation of caspase-3. Western blotting analysis provided direct evidence for the involvement of a lysosomal enzyme, cathepsin L. These findings indicate that lysosomal dysfunction induced by a reduction in ATP results in leakage of lysosomal enzymes into the cytosolic compartment and that lysosomal enzyme(s) may be involved in activation of caspase-3 during apoptosis in P39 cells treated with etoposide.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Endopeptidases
/
Síndromes Mielodisplásicas
/
Apoptose
/
Macrolídeos
/
Caspases
/
Grupo dos Citocromos c
/
ATPases Vacuolares Próton-Translocadoras
/
Leucina
Limite:
Humans
Idioma:
En
Revista:
Cancer Res
Ano de publicação:
2001
Tipo de documento:
Article
País de afiliação:
Japão