Association between MGMT promoter hypermethylation and p53 mutation in glioblastoma.

O(6)-methylguanine-DNA methyltransferase (MGMT) is a DNA repair enzyme that removes alkyl groups from the O(6) position of guanine. MGMT is transcriptionally silenced by promoter hypermethylation in several human neoplasia. We used methylation-specific PCR (MSP) to analyze the MGMT promoter methylation status of 50 glioblastoma tumors. Hypermethylation was detected in 24 of 50 (48%) samples. We also analyzed mutant p53 expression by immunohistochemical analysis of glioblastoma tissue samples. A significant association was found between MGMT methylation and p53 mutation status (p< .05). These results suggested that epigenetic inactivation of MGMT plays an important role in the survival of glioblastoma patients and this inactivated gene involved in p53 mutation.