[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.