Thin layer chromatography-based assay of O6-methylguanine-DNA methyltransferase activity in tissue.

Expression of the DNA repair enzyme O(6)-methylguanine-DNA methyltransferase (MGMT) in tumor correlates with resistance to alkylating agents, and depletion of MGMT activity can enhance chemotherapy-induced tumor cytotoxicity. The most common assays of MGMT activity are time-consuming and employ radioactivity. The assay described here uses a fluorescently labeled O(6)-benzylguanine derivative in conjunction with thin layer chromatography to eliminate the use of radioactivity and allows MGMT activity to be rapidly measured in minimally prepared cell or tissue extracts.