Role of DNA methylation in the suppression of Apaf-1 protein in human leukaemia.
Apaf-1 protein deficiency occurs in human leukaemic blasts and confers resistance to cytochrome-c-dependent apoptosis. Demethylation treatment with 5-aza-2'-deoxycytidine (5aza2dc) increased the sensitivity of the K562 leukaemic cell line to UV light-induced apoptosis in association with increased Apaf-1 protein levels. There was no correlation between Apaf-1 protein expression and Apaf-1 mRNA levels after the demethylation treatment. Methylation-specific polymerase chain reaction was used to show that the methylation can occur within the Apaf-1 promoter region in leukaemic blasts. Apaf-1 DNA methylation was demonstrated in acute myeloid leukaemia, chronic myeloid leukaemia and acute lymphoid leukaemia, suggesting that it is not specific to a particular leukaemia subtype. Apaf-1 protein expression did not correlate with Apaf-1 mRNA levels in human leukaemic blasts. Some leukaemic cells expressed high levels of Apaf-1 mRNA but low levels of Apaf-1 protein. This study suggests that Apaf-1 DNA promoter methylation might contribute to the inactivation of Apaf-1 expression. However, Apaf-1 protein levels might also be controlled at post-transcription level.
Fu
Wei-Neng
WN
Department of Haematology/Oncology, St Bartholomew's and the Royal London School of Medicine and Dentistry, UK.
Bertoni
Francesco
F
Kelsey
Stephen M
SM
McElwaine
Suzanne M
SM
Cotter
Finbarr E
FE
Newland
Adrian C
AC
Jia
Li
L
D017209:Apoptosis / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects; D053477:Apoptotic Protease-Activating Factor 1; D001374:Azacitidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D003596:Cytosine / Q000378:metabolism; D019175:DNA Methylation; D000077209:Decitabine; D006801:Humans; D007938:Leukemia / Q000235:genetics* / Q000473:pathology / Q000628:therapy; D016133:Polymerase Chain Reaction / Q000379:methods; D011401:Promoter Regions, Genetic; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D012016:Reference Values; D017422:Sequence Analysis, DNA / Q000379:methods; D014407:Tumor Cells, Cultured; D014466:Ultraviolet Rays
C506592:APAF1 protein, human; D053477:Apoptotic Protease-Activating Factor 1; D011506:Proteins; D000077209:Decitabine; D003596:Cytosine; D001374:Azacitidine