Anatomical specificity of O6-methylguanine DNA methyltransferase protein expression in glioblastomas

O6-methylguanine DNA methyltransferase (MGMT) is one of the important tumor-related biomarkers and is considered to be a prognostic factor for glioblastoma. This study aimed to investigate the anatomical location of tumor-related MGMT protein expression in histologically confirmed de novo glioblastoma multiforme (GBM). Preoperative magnetic resonance images were retrospectively examined from GBM patients. Tumor tissues were manually segmented based on the structural image of each patient and subsequently registered to a standard brain atlas. Superimposition of the tumor tissues was carried out in patients with and without epigenetic changes. We used voxel-based lesion symptom mapping (VLSM) to identify the specific brain regions that were associated with level of MGMT protein expression. The tumors with low expression of MGMT protein and those with high expression of MGMT protein showed not significant differences in tumor size on T2 imaging. The VLSM analysis demonstrated that tumors with low expression of MGMT protein were more likely to occur in the right temporal-parietal lobe, while tumors with high expression of MGMT protein occurred more often in the left frontal lobe. Based upon VLSM data, our results suggest that the epigenetic changes, which occur during tumorigenesis, may have anatomical specificity. The identified correlation between molecular biomarkers and anatomical distribution underscores the current understanding of the biological characteristics of glioblastoma.