Measurement of O-6-methylguanine-DNA methyltransferase activity using oligonucleotides and restriction enzyme in human brain tumors

We determined the levels of MGMT activity in 46 human brain tumors, using oligonucleotides containing O-6-methylguanine at a PvuII recognition site, and correlated MGMT activity with chemotherapeutic effectiveness in 14 patients with high-grade gliomas who received ACNU chemotherapy. The results characterize MGMT activities among different types and within individual types of human brain tumors. A certain fraction of gliomas exhibited a low value of MGMT activity. Tumors showing a low MGMT activity responded well to ACNU and resulted in prolongation in the time to tumor progression. Thus, the low MGMT activity of gliomas may provide a theoretical basis for application of CENU chemotherapy.