Suppression of Gamma- and Neutron-induced Neoplastic Transformation by Ascorbic Acid in Balb/c 3T3 Cells

Abstract

The effects of ascorbic acid on the neoplastic transformation induced by ⁶⁰Co γ-rays or ²⁵²Cf fission neutrons were studied. The transformation induced by each of the radiations was markedly suppressed when ascorbic acid was added daily to the culture medium during the first 8 days of the post-irradiation period. If ascorbic acid was added for a total of 8 days as mentioned above, but with 1 day interruption in the middle, the suppression of transformation was decreased. Ascorbic acid also suppressed the promotion of radiation transformation by 12-O-tet-radecanoylphorbol-13-acetate (TPA) when both chemicals were added to the medium together. However, promotion of radiation transformation by TPA was observed if both the chemicals were added sequentially during the post-irradiation period, i.e. ascorbic acid for the first 7 days followed by TPA. These results suggest that continuous administration of ascorbic acid for a certain number of days is needed to suppress the radiation transformation, and also suggest that it acts on the promotion stage of transformation.