Detection of O6-methylguanine-DNA methyltransferase gene methylation status in IDH-wild type glioblastomas using methylation-specific qPCR: a first report from Morocco.

Abstract

We tried, through this work, to highlight the first detection of the methylation status of the O6-methylguanine-DNA methyltransferase gene (MGMT) promoter in IDH-wild-type glioblastomas with observation of the expression of IDH1, ATRX, and P53 by immunohistochemistry. Across eight formalin-fixed, paraffin-embedded tissue blocks (FFPE) from glioblastoma patients, we collected tumor tissue samples. We examined the methylation status of the MGMT gene promoter using a real-time methylation-specific PCR technique (MS-qPCR). In addition, we observed the molecular alterations caused by mutations in IDH1, ATRX, and p53 using immunohistochemistry (IHC). All cases studied had a wild-type form of IDH1, loss of ATRX expression was observed in five samples. In two cases, the mutated form of p53 was expressed. The level of p53 expression ranged from intense (>80% of tumor cells) to weak (>10% of tumor cells), and less than 10% labeling was considered negative. In our study, when analyzing the methylation profiles of the MGMT gene promoter, we found that two cases, specifically sample 2 and sample 5, exhibited positive methylation. Sample 2 had a methylation rate of 6.8%, while sample 5 showed a methylation rate of 27%. In contrast, sample 6 had a methylation rate of 0.05%, which fell below the established methylation cutoff point of 0.6%. Therefore, sample 6 was considered negatively methylated because its methylation rate was significantly lower than the established threshold. This study identifies MGMT promoter methylation in a subset of glioblastomas IDH-wild-type. These findings highlight the molecular diversity of glioblastomas and suggest potential targets for tailored therapeutic strategies.