Procainamide inhibits DNA methyltransferase in a human T cell line.

Procainamide, a widely used antiarrythmic, causes DNA hypomethylation in the human T cell line Jurkat, but the mechanism is unknown. We report that procainamide inhibits the DNA methyltransferase catalyzed transfer of methyl groups from S-adenosylmethionine to DNA, but has no effect on other known regulators of DNA methylation. Our results suggest that procainamide could inhibit cellular DNA methylation by inhibiting DNA methyltransferase activity.