OBJECTIVE: To explore the role of hypemethylation of DLC-1 gene in the pathogenesis of multiple myeloma (MM) and examine the effects of arsenic trioxide (As(2)O(3))-induced demethylation of DLC-1 gene in U266 cell line.METHODS: The methylation status of DLC-1 gene was detected by methylation specific PCR (MSP) in MM patients from 2008 to 2012. And the expression of DLC-1 gene mRNA was determined by reverse transcription-polymerase chain reaction (RT-PCR). Methylation statuses of DLC-1 gene exposed to As(2)O(3) were detected by bisulfite sequencing PCR (BSP). And the mRNA expressions of DLC-1 and DNA methyltransferase (DNMT1, T3a and 3b) were determined by real-time fluorescence quantitative PCR (RTFQ-PCR).RESULTS: Hypermethylation of CpG island of DLC-1 gene was observed in 37/52 (71.15%) MM patients. DLC-1 gene was not expressed after methylation. As(2)O(3) could induce DLC-1 gene demethylation. After 72-houe treatments of 0.5, 1.0 and 2.0 µmol/L As(2)O(3), the methylation rate of DLC-1 gene dropped from 95.38% to 63.07%, 30.00% and 7.69%. As compared with the untreated group, the expression of DLC-1 gene mRNA increased to (1.60 ± 0.09), (3.66 ± 0.17) and (5.29 ± 0.15) folds after exposures (all P < 0.05) . And As(2)O(3) could induce the expression of DNMT1, DNMT3a, DNMT3b gene mRNA (all P < 0.05).CONCLUSIONS: Methylation of DLC-1 gene is essential in the pathogenesis of MM and may provide a new diagnostic technique and drug target for the treatment of MM. And As(2)O(3) may activate the expression of DLC-1 gene through demethylation.
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