Aberrant hypomethylation of SALL4 gene in patients with myelodysplastic syndrome.

The abnormalities of SALL4 gene, which encodes a zinc-finger transcription factor and is essential for developmental events, have been found to be involved in tumorigenesis. In this study, we investigated the methylation status of the CpG island of SALL4 promoter region in myelodysplastic syndrome (MDS) using methylation-specific PCR (MSP). Aberrant hypomethylation of SALL4 gene was found in 21.7% (18/83) of the cases analyzed. A significantly positive correlation was identified between the level of SALL4 transcript and the status of SALL4 hypomethylation (R=0.641, P<0.001). No correlation was found between SALL4 hypomethylation and clinical parameters. However, the frequency of SALL4 hypomethylation significantly increased in higher risk MDS (14% in Low/Int-1 versus 39% in Int-2/High, P=0.031). The association between SALL4 hypomethylation and the mutations in three methylation modifiers (IDH1, IDH2 and DNMT3A) was not observed. Although the estimated 50% survival time of the SALL4-hypomethylated group was shorter than that of SALL4-methylated group (11.0 months vs. 20.0 months), the difference was not statistically significant (P=0.430). These findings suggest that hypomethylation of SALL4 promoter is a common event in MDS.