Radiosensitization of human fibroblasts by 3-aminobenzamide: an inhibitor of poly(ADP-ribosylation).

The poly(ADP-ribose) synthetase inhibitor 3-aminobenzamide (3AB) increases the radiosensitivity of normal human fibroblasts in tissue culture in a dose-dependent manner at noncytotoxic concentrations. 3AB was also found to inhibit the repair of potentially lethal damage as well as the recovery occurring when radiation was delivered as fractionated vs single exposures. However, repair as measured by an increased survival when radiation is delivered at low dose rate compared to high dose rate was not effected by 3AB administration.