Promoting effect of nicotinamide on the development of renal tubular cell tumors in rats initiated with diethylnitrosamine.

Nicotinamide administered in the drinking water of male Fischer 344 rats increased the number of renal tubular cell tumors of rats treated with an i.p. injection of diethylnitrosamine (DEN) (25-mg/kg body weight). The incidence of kidneys with tumors in rats treated with DEN alone was 5%. In rats which received DEN and then were promoted with either 30 or 6.7 mM nicotinamide in their drinking water, the incidence of kidneys with tumors rose to 59 and 28%, respectively. Rats which were on 30 mM nicotinamide but did not receive DEN had no kidney tumors present. These results show that nicotinamide promoted DEN-induced renal tubular cell tumorigenesis.