DNA repair in cells of C57bl mice after radiation and in vivo treatment with a DNA site modulator of poly(ADP-ribose)-polymerase.

Poly(ADP-ribose)-polymerase is an important cellular regulatory enzyme which can change chromatin structure and function. Action mechanisms and activation of the enzyme are described. The synthesis of poly(ADP-ribose) can be modulated by interaction of substances with the DNA binding site of the poly(ADP-ribose)-polymerase. The involvement of this enzyme in DNA repair, differentiation, carcinogenesis and DNA replication has been suggested. Unscheduled DNA synthesis in spleen cells of C57bl mice drug treated and gamma irradiated in vivo and 3 days later UV irradiated in vitro showed a slight decrease in grain numbers of treated animals. Poly(ADP-ribose)-synthesis was highest in the irradiated groups 18 hours after gamma irradiation. A higher amount of supercoils in DNA was generated by both drugs used. In one long-term experiment the gamma-irradiated group of mice had the highest incidence of lymphomas, while the combined treatment group, modulated and gamma irradiated, showed a lymphoma level like in the unirradiated control group.