# MGMT (O6-methylguanine-DNA methyltransferase)

Source: https://onco.cc/targets/mgmt-protein/  
OnCo record `mgmt-protein` (Target). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

MGMT is a DNA repair enzyme that removes the damage temozolomide causes; when the gene is switched off by methylation the tumour cannot repair itself and the drug works better.

## Summary

MGMT is a suicide enzyme that transfers alkyl groups off the O6 position of guanine onto itself, reversing the lesion that temozolomide and nitrosoureas rely on. Promoter methylation silences the gene in about 40 percent of glioblastomas and predicts longer survival with temozolomide; the readout page under this target carries the test methods and the trials that use methylation to select or spare chemotherapy.

## Fields

- Kind: Target
- Last checked: 2026-09-23
- Also known as: O-6-methylguanine-DNA methyltransferase; AGT; O6-alkylguanine DNA alkyltransferase
- Tags: biomarker-parent
- Symbol: MGMT
- Class: enzyme
- Biology: Loss of MGMT leaves O6-methylguanine unrepaired, which mispairs with thymine and triggers mismatch-repair-driven cell death; tumours that lose mismatch repair as well become hypermutated and resistant.
- Where found: Glioblastoma (promoter methylation in about 40 percent); Lower-grade gliomas; Neuroendocrine tumours (low MGMT expression and alkylator response)

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/O-6-methylguanine-DNA_methyltransferase
- HGNC HGNC:7059: https://www.genenames.org/data/gene-symbol-report/#!/hgnc_id/HGNC:7059
- UniProt P16455: https://www.uniprot.org/uniprotkb/P16455/entry

## Connected records

- biomarkers: [MGMT promoter methylation](https://onco.cc/biomarkers/mgmt-promoter-methylation/)
- cancers: [Glioma & glioblastoma](https://onco.cc/cancers/glioblastoma/)
- drugs: [Temozolomide](https://onco.cc/drugs/temozolomide/)
- terms: [MGMT promoter methylation](https://onco.cc/terms/mgmt/)
- collections: [CIViC](https://onco.cc/collections/civic/)

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JSON: https://onco.cc/api/v1/entities/mgmt-protein.json