The significance of methylation status of secreted frizzled-related protein gene promoter in acute leukemia

Objective: To investigate the relationship between promoter hypermethylation of secreted frizzled-related protein (SFRP) gene and acute leukemia (AL).

Methods: We examined the promoter methylation status of SFRP1, 2, 4 and 5 in primary or relapsed AL patients, cell lines (HL60, NB4, Molt-4 and Jurkat) and peripheral blood mononuclear cells from healthy people with methylation-specific PCR (MSP).

Results: None of the normal mononuclear cells showed methylation of any SFRP genes. The frequencies of aberrant methylation among the samples were 33.9% (20/59) for SFRP1, 23.7% (14/59) for SFRP2, 6.8% (4/59) for SFRP4 and 10.2% (6/59) for SFRP5 in acute myelocytic leukemia (AML), and 39.3% (11/28) for SFRP1, 28.6% (8/28) for SFRP2, 25.0% (7/28) for SFRP4 and 32.1% (9/28) for SFRP5 in acute lymphoblastic leukemia (ALL). Hypermethylation of SFRP1, 2, 5 genes were present in the 4 AL cell lines. SFRP4 was methylated in NB4, Molt-4 and Jurkat cell lines. However, methylation and unmethylation of SFRP4 were both detected in HL60.

Conclusions: Hypermethylation of SFRP genes is a common event in the evolution of AL. Methylation of SFRP genes might serve as potential independent biomarkers for early detection of AL.