Artículos de revistas
Correlation of MGMT promoter methylation status with gene and protein expression levels in glioblastoma
Fecha
2011Registro en:
Clinics, v.66, n.10, p.1747-1755, 2011
1807-5932
10.1590/S1807-59322011001000013
Autor
UNO, Miyuki
OBA-SHINJO, Sueli Mieko
CAMARGO, Anamaria Aranha
MOURA, Ricardo Pereira
AGUIAR, Paulo Henrique de
CABRERA, Hector Navarro
BEGNAMI, Marcos
ROSEMBERG, Sérgio
TEIXEIRA, Manoel Jacobsen
MARIE, Suely Kazue Nagahashi
Institución
Resumen
OBJECTIVES: 1) To correlate the methylation status of the O6-methylguanine-DNA-methyltransferase (MGMT) promoter to its gene and protein expression levels in glioblastoma and 2) to determine the most reliable method for using MGMT to predict the response to adjuvant therapy in patients with glioblastoma. BACKGROUND: The MGMT gene is epigenetically silenced by promoter hypermethylation in gliomas, and this modification has emerged as a relevant predictor of therapeutic response. METHODS: Fifty-one cases of glioblastoma were analyzed for MGMT promoter methylation by methylation-specific PCR and pyrosequencing, gene expression by real time polymerase chain reaction, and protein expression by immunohistochemistry. RESULTS: MGMT promoter methylation was found in 43.1% of glioblastoma by methylation-specific PCR and 38.8% by pyrosequencing. A low level of MGMT gene expression was correlated with positive MGMT promoter methylation (p = 0.001). However, no correlation was found between promoter methylation and MGMT protein expression (p = 0.297). The mean survival time of glioblastoma patients submitted to adjuvant therapy was significantly higher among patients with MGMT promoter methylation (log rank = 0.025 by methylation-specific PCR and 0.004 by pyrosequencing), and methylation was an independent predictive factor that was associated with improved prognosis by multivariate analysis. DISCUSSION AND CONCLUSION: MGMT promoter methylation status was a more reliable predictor of susceptibility to adjuvant therapy and prognosis of glioblastoma than were MGMT protein or gene expression levels. Methylation-specific polymerase chain reaction and pyrosequencing methods were both sensitive methods for determining MGMT promoter methylation status using DNA extracted from frozen tissue.