Nicotinamide as a radiosensitizer of a C3H mouse mammary adenocarcinoma.

Inhibitors of the chromosomal enzyme ADP-ribosyl transferase, like nicotinamide, have been shown to inhibit DNA strand rejoining and also to potentiate the lethality of DNA damaging agents in vitro. We have examined the radiosensitizing potential of nicotinamide in vivo by using transplanted C3H mouse mammary adenocarcinomas as our model system. Our data indicate a radiosensitizing effect for nicotinamide.