MLH1 mediates PARP-dependent cell death in response to the methylating agent N-methyl-N-nitrosourea.
Br J Cancer
; 101(3): 441-51, 2009 Aug 04.
Article
en En
| MEDLINE
| ID: mdl-19623177
ABSTRACT
BACKGROUND:
Methylating agents such as N-methyl-N-nitrosourea (MNU) can cause cell cycle arrest and death either via caspase-dependent apoptosis or via a poly(ADP-ribose) polymerase (PARP)-dependent form of apoptosis. We wished to investigate the possible role of MLH1 in signalling cell death through PARP.METHODS:
Fibroblasts are particularly dependent on a PARP-mediated cell death response to methylating agents. We used hTERT-immortalised normal human fibroblasts (WT) to generate isogenic MLH1-depleted cells, confirmed by quantitative PCR and western blotting. Drug resistance was measured by clonogenic and cell viability assays and effects on the cell cycle by cell sorting. Damage signalling was additionally investigated using immunostaining.RESULTS:
MLH1-depleted cells were more resistant to MNU, as expected. Despite having an intact G(2)/M checkpoint, the WT cells did not initially undergo cell cycle arrest but instead triggered cell death directly by PARP overactivation and nuclear translocation of apoptosis-inducing factor (AIF). The MLH1-depleted cells showed defects in this pathway, with decreased staining for phosphorylated H2AX, altered PARP activity and reduced AIF translocation. Inhibitors of PARP, but not of caspases, blocked AIF translocation and greatly decreased short-term cell death in both WT and MLH1-depleted cells. This MLH1-dependent response to MNU was not blocked by inhibitors of ATM/ATR or p53.CONCLUSION:
These novel data indicate an important role for MLH1 in signalling PARP-dependent cell death in response to the methylating agent MNU.
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Proteínas Nucleares
/
Poli(ADP-Ribosa) Polimerasas
/
Apoptosis
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Proteínas Adaptadoras Transductoras de Señales
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Alquilantes
/
Metilnitrosourea
Límite:
Humans
Idioma:
En
Revista:
Br J Cancer
Año:
2009
Tipo del documento:
Article
País de afiliación:
Reino Unido