ABSTRACT
glioma; U87 cell; U251 cell; MAGE-A1; MAGE-A3; DNA methylation; histone acetylation@#To detect the expressions of melanoma antigen genes MAGE-A1 and MAGE-A3 in glioma tissues and to explore their clinical significance. Methods: Seventy-eight surgically resected glioma specimens and 15 normal brain tissue samples from donors suffered traffic accidence were collected at the Department of Neurosurgery, the Fourth Hospital of Hebei Medical University between January 2006 and January 2010, and the mRNAexpressions of MAGE-A1 and MAGE-A3 in collected tissues were detected with RT-PCR; their associations with the overall survival of patients were also analyzed.The promoter methylation status of the two genes was observed with methylation specific PCR, and the relationship between the gene expressions and promoter methylation status was analyzed. The expressions of MAGE-A1 and MAGE-A3 genes in U251 and U87 glioma cell lines were detected by RT-PCR before and after the treatment with DNA methyltransferase inhibitor 5-aza-CdR and/or histone deacetylase inhibitor trichostatin A (TSA). Results:The positive expression rates of MAGE-A1 and MAGE-A3 genes in glioma tissues were 65.34% and 38.46%, respectively; however, the two genes were not detected in 15 cases of normal brain tissues.The 5-year overall survival of patients in MAGEA1 positive expression group was shorter than that of negative expression group (P<0.05). There was significant correlation between the mRNA expressions of two genes and their promoter methylation status (all P<0.01). There was no mRNA expressions of MAGEA1 and MAGE-A3 in U87 cells untreated with 5-Aza-CdR and TSA, but a small amount of MAGE-A1 mRNA and MAGE-A3 mRNA were detected in U251 cells. TSA alone could not activate the expression of MAGE-A1 and MAGE-A3 genes. 5-Aza-CdR alone or in combination with TSA could activate the expression of both genes, and the combined effect was better than that of single administration. Conclusion: There are different degrees of MAGE-A1 and-A3 expression in glioma tissues, and the expression of MAGE-A1 is a negative prognostic factor for glioma patients. DNApromoter methylation and histone acetylation are important mechanisms of the activation of MAGE-A1 and MAGE-A3 expression.