Alteration of neutron and x-ray induced oncogenic transformation by actinomycin D

The antineoplastic agent actinomycin D has been used successfully in the clinic for the treatment of some cancers. With the current trend of combined treatment modalities in cancer therapy, the question of late effects-modification by chemotherapy agents such as Act D and radiation becomes important. Chemically-induced transformation frequencies (TF) can be modified upward or downward depending on the sequence of carcinogen and Act D. Further, cells exposed to Act D after X-ray exposure show a significant reduction in their TF. In a series of comparisons between C3H/1OT 1/2 cells exposed to X-rays and 430 Kev neutrons followed by Act D (5ng/ml for 24 hrs), neutron-irradiated to either neutrons alone or Act D alone. The enhancing effect of Act D after neutron exposure is under further investigation