Epigenetics of silenced expression of maspin in glioma cell lines U87 and U251

Abstract

Objective To study the relationship between the silenced expression of mammary serine protease inhibitor (maspin) and epigenetics in human glioma cell lines U87 and U251.Methods Reverse transcription polymerase chain reaction (RT-PCR) and Western blotting were used to examine the expression of maspin.Methylation status of the maspin promoter was detected by methylation-specific polymerase chain reaction (MSP) and bisulphite genomic sequencing.RT-PCR was used to examine the expression of maspin after U87 and U251 cells were treated with 12 (or 15) μmol/L 5-Aza-2-deoxyeytidine (5-Aza-dC) and/or 500 nmol/L trichostatin A (TSA).Results A CpG island in the 5' promoter region of maspin was methylated.Maspin was silenced in human glioma cell lines U87 and U251.The relative intensity of maspin was 0.030 3 ±0.000 6,0.019 6 ±0.001 6,and 0.052 6 ±0.003 4 in 5-Aza-DC,TSA,and 5-Aza-DC plus TSA pretreated U87 cells,and 0.001 2 ± 0.000 1 in control group.The relative intensity of maspin was 0.012 2 ± 0.000 8,0.024 9 ± 0.001 2,and 0.038 4 ± 0.003 1 in 5-Aza-DC,TSA,and 5-Aza-DC plus TSA pretreated U251 cells,and 0.002 2 ± 0.00 3 in control goup.U87,and U251could could be restored by treatment with 5-Aza-DC and/or TSA (P ＜ 0.01).Conclusion Maspin is silenced by promoter methylation and histone modification,and 5-Aza-DC and/or TSA can restore the transcription of maspin in U87 and U251 cells. Key words: Maspin ; Glioma; Promoter methylation; Histone acetylation