Expression of mRNA for DNA methyltransferase 1, 3a and 3b in bladder carcinoma

Objective To evaluate the significance of aberrant DNA methyltransferase (DNMTs) expression in human bladder carcinoma. Methods The levels of mRNAs encoding DNA methyltransfer- ases were measured by reverse transcription followed by semi-quantitative detection of PCR products. Re- sults The positive expression rate and the average level of mRNA for DNMT1 and DNMT3b in bladder cancers were all significantly higher than in normal bladder mucosae (P 0. 05), whereas the expression of DNMT3a in the two groups showed no significant difference (P 0. 05). There was no significant correlation between the expression of DNMTs and the clinicopathological parameters of tumors (histologi- cal classification, clinical stage, morphological type of tumors, primary case or recurrence case, P 0. 05). Over-expression of DNMT1 mRNA was significantly associated with that of DNMT3b (P 0. 01). Con- clusion Both over-expression of the maintenance DNA methyltransferase DNMT1 and over-expression of de novo DNA methyltransferase, DNMT3b, are involved in human bladder carcinogenesis. There could be a certain co-regulation mechanism between DNMT1 and DNMT3b.