[Effects of uroacitides on the methylation of PTEN gene in myelodysplastic syndrome cells and its mechanism].

OBJECTIVE: To investigate the methylation patterns of PTEN gene in myelodysplastic syndrome (MDS) cell line MUTZ-1 cells and the primary cells, to explore the effects of uroacitides (CDA- II) on the methylation patterns, and to provide novel target therapy for MDS.

METHODS: Reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot were used to determine the expression of PTEN and DNA methyltransferases (DNMTs) as well as the effects of CDA-II on them. Methylation specific PCR (MSP) was used to identify the methylation patterns of PTEN and the effects of CDA-II on them.

RESULTS: PTEN was completely methylated in high-risk MDS and acute myeloid leukemia (AML) transformed from MDS. High expressions of DNMTs proteins, especially DNMT3b protein were found in high-risk MDS and AML cells transformed from MDS. PTEN expression level was increased from 0.02 ± 0.01 at control group to 0.23 ± 0.11, 0.54 ± 0.11 and 0.92 ± 0.13 after treatment with CDA-II at 2, 4 and 8 mg/ml (P<0.01). If the cells were treated with CDA-II at 4 mg/ml for 12, 24 and 48 hours, PTEN expression level was up- regulated to 0.15 ± 0.06, 0.52 ± 0.12 and 0.89 ± 0.13, which were significantly higher than that of control group 0.02 ± 0.01 (P<0.01). CDA-II could significantly down-regulate the expression of DNMTs in MUTZ-1 cells in a dose-(r=0.999, 0.992, 0.995, P<0.01) and time-dependent (r=0.989, 0.981, 0.985, P<0.05) manner, which led to the demethylation of PTEN. Among them, DNMT1 was the most downregulated (F=21.256, P<0.05).

CONCLUSION: PTEN gene was hypermethylated in high-risk MDS, and target therapy of PTEN demethylation might be a new strategy for MDS therapy. CDA-II could down regulate the expression of DNMTs and lead to PTEN demethylation which induce MUTZ-1 cells apoptosis.