[The expression of DNA methyltransferase DNMT1, 3A and 3B in acute leukemia and myelodysplastic syndrome].

OBJECTIVE: To explore the relationship between methyltransferases and the pathogenesis of acute leukemia (AL) and the leukemic transformation of myelodysplastic syndromes (MDS). METHODS: Semi-quantitative RT-PCR method was used to detect the mRNA expression level of DNMT1, 3A and 3B in bone marrow cells from 75 patients with AL or MDS. RESULTS: There was no significant difference in mRNA expression level of DNMTs between a low-risk MDS group (n = 21) and a normal group. However, increased expression level of DNMT1, 3A and 3B was found in 47.6%, 47.6% and 42.9% of the patients in the low-risk group, respectively, if the upper limit of 80% of the normal controls was considered as the critical level. In high-risk MDS (n = 13), a more proportion of the cases with increased expression level of DNMTs were found, that was 53.8%, 76.9% and 92.3% respectively, and only expression level of DNMT3B was significantly higher than that in the low-risk MDS group (P < 0.01). In the AL group (n = 41) expression level of all the three subtypes was coordinately higher than that in the MDS group (P < 0.01), companying with a more frequency of 92.7%, 97.6% and 100%. Comparing with the AML group, a significantly increased expression level of DNMT1 (P < 0.01) with the same level of DNMT 3A and 3B was interestingly observed in the ALL group. CONCLUSIONS: It is possible that up-regulated DNMTs contribute to the pathogenesis of AL and the leukemic transformation of MDS, and DNMT3B might be the most important enzyme among the three subtypes.