The Effects of Niacin on DNA Repair after N-Methyl-N'-nitro-N-nitrosoguanidine Treatment in Normal Human Lymphocytes

Abstract

We have investigated the effects of niacin on NAD levels and on DNA repair in human lymphocytes. When lymphocytes were incubated in culture medium with various concentrations of niacin, incubation of lymphocytes with nicotinic acid at 5μM or nicotin-amide at 10 mM caused a 2-3 fold increase in NAD content. Under these conditions lymphocytes were treated with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), Interestingly, the rejoining of DNA strand breaks was promoted by nicotinic acid but nicotinamide inhibited the rejoining.