BACKGROUND: DNA methylation of CpG islands within the promoters of specific 
genes may play roles in tumor initiation and progression. It has been suggested 
such events may serve as critical check points.
METHODS: The present study analyzed the methylation status of CpG islands within 
the promoters of secreted frizzled-related proteins (SFRPs) in 87 acute leukemia 
(AL) patients, 20 normal controls, and four AL cell lines. 5-aza-2'- 
deoxycytidine (5-Aza-CdR), an inhibitor of DNA methylation, was employed to 
determine its effect on SFRP expression.
RESULT: Methylation of at least one SFRP promoter was observed in 69% of the AL 
patients analyzed. In addition, methylation of all four SFRP promoters was 
observed in Molt-4, Jurkat, HL60 and NB4 cells. In Jurkat cells, methylation 
levels of four SFRP promoters decreased in a dose-dependent manner upon 
treatment with 5-Aza-CdR, which coincided with increased mRNA expression. With 
increasing 5-Aza-CdR concentrations, the expression of DNA methyltransferases, 
DNMT3A and DNMT3B, significantly decreased in a dose-dependent manner.
CONCLUSION: The present study demonstrated that SFRP gene methylation may be 
involved in AL progression, with a possible epigenetic mechanism influencing Wnt 
signaling.