RESUMO
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.
