10124- GEN-6 ANALYSIS OF DNA METHYLATION IN DIFFERENTIATION AND DEDIFFERENTIATION MECHANISMS OF GLIOMA STEM-LIKE CELLS

Abstract The presence of glioma stem cells, capable of self-renewal and multilineage differentiation, is one of the reasons why brain tumors are difficult to treat. Gliomas are predicted to arise from the accumulation of genetic abnormalities in glial cells or their progenitor cells at the origin of tumorigenesis. It has been suggested that these glioma stem cells can acquire different properties through epigenomic reprogramming by interacting with the surrounding environment. In this study, we investigated whether DNA methylation, an epigenomic factor, is involved in the mechanism of glioma differentiation and dedifferentiation. DNA methylation was analyzed by real-time methylation-specific PCR (MSP). The promoter region (CpG island) of EZH2 (histone H3 lysine 27 (H3K27) methyltransferase), which has been reported to be involved in the mechanism of differentiation and dedifferentiation, was examined. 0125-GSC and 0222-GSC which are established from patient tumors were cultured in neurobasal medium with supplements and used as glioma stem-like cells. These cells formed sphere and expressed stem cell markers. S0125 and S0222 were adherent and cultured in D-MEM with 10 % fetal calf serum. The DNA methylation rate of EZH2 was increased in S0125 and S0222. Furthermore, real-time PCR analysis revealed that the expression of EZH2 mRNA was decreased in S0125 and S0222. These results suggest that changes in DNA methylation and gene expression of EZH2 may be involved in the differentiation and dedifferentiation of glioma cells.Keyword: Glioblastoma stem-like cell, Differentiation, EZH2 methylation