O6-methylguanine-DNA methyltransferase activity in cerebral gliomas. A guidance for nitrosourea treatment?
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Updated: Oct 21, 2026
Continuous Fluorescence-Based Endonuclease-Coupled DNA Methylation Assay to Screen for DNA Methyltransferase Inhibitors
Published on: August 5, 2022
K Mineura1, I Izumi, N Kuwahara
1Neurological Service, Akita University Hospital, Japan.
Abstract:
The activity of O6-methylguanine-DNA methyltransferase (O6-MT), which removes O6-methyl residues from O6-methylguanine-DNA leading to cell death, has been reported to correlate with sensitivity to nitrosoureas used for chemotherapy of gliomas. We determined O6-MT activity in tumors and matched brain tissue from patients with gliomas. Histological diagnoses were: six malignant astrocytomas, two glioblastomas, two oligodendrogliomas, one ependymoma, and one medulloblastoma. In all cases but one, the activity ranged widely from 39 to 258 fmol/mg protein extract. The wide range of activity of the tumor tissue may indicate varying degree of sensitivity to nitrosoureas. The activity of brain tissue, available from the peritumoral region of five cases, varied between 38 to 415 fmol/mg. Four of the five regions showed a higher value than the respective tumor, and one showed a lower value.
Insights
O6-methylguanine-DNA methyltransferase (O6-MT) activity varies in glioma tumors and surrounding brain tissue. This enzyme
Area of Science:
- Oncology
- Molecular Biology
- Neuroscience
Background:
- O6-methylguanine-DNA methyltransferase (O6-MT) activity is linked to patient response to nitrosourea chemotherapy for brain tumors.
- Nitrosoureas are a class of chemotherapeutic agents used in glioma treatment.
Purpose of the Study:
- To measure O6-MT activity in glioma tumors and matched normal brain tissue.
- To assess the potential correlation between O6-MT levels and sensitivity to nitrosourea chemotherapy.
Main Methods:
- O6-MT activity was quantified in protein extracts from tumor and peritumoral brain tissue samples.
- Histological diagnoses included various glioma subtypes: astrocytomas, glioblastomas, oligodendrogliomas, ependymoma, and medulloblastoma.
Main Results:
- O6-MT activity exhibited a wide range in tumor tissues (39-258 fmol/mg protein extract).
- Peritumoral brain tissue showed even wider activity variations (38-415 fmol/mg).
- Four out of five peritumoral samples had higher O6-MT activity than their corresponding tumors.
Conclusions:
- Significant variability in O6-MT activity exists within glioma tumors and surrounding brain.
- Observed O6-MT activity ranges suggest differential patient sensitivity to nitrosourea-based chemotherapies.
- Further research is warranted to elucidate the clinical implications of O6-MT activity in gliomas.
