title: Transformation frequency of Syrian golden hamster cells and its modulation by ultraviolet irradiation.
abstract: UV (253.7 nm) exposure of Syrian golden hamster cells seeded for colony formation caused an induction of transformation without any other insult. Analysis of the quantitative data demonstrated a lack of a threshold response and a transfomation frequency proportional to UV dose. No transformation occurred in unirradiated colonies. When cells seeded for colony formation are exposed to UV and subsequently treated with AcAAF, a carcinogen known to induce UV-like damage, neither an additive nor a synergistic effect occurred. Caffeine at nontoxic concentrations potentiates lethality caused by AcAAF and also the number od colonies transformed by AcAAF when added post-AcAAF. The addition of a constant amount of caffeine (50 micrograms/ml) for 48 hours at different intervals after carcinogen resulted in maximum enhancement (10- to 17-fold) when added 4 hours post-AcAAF. UV-associated transformation was enhanced by pretreating the cells with a nontransforming dose of X-irradiation 48 hours before UV. The increase in transformation frequency was 6- to 12-fold per colony and 3- to 6-fold per dish.
mesh_terms: D000099:Acetoxyacetylaminofluorene / Q000008:administration & dosage; D000818:Animals; D002110:Caffeine / Q000008:administration & dosage; D002471:Cell Transformation, Neoplastic; D002478:Cells, Cultured; D003043:Cocarcinogenesis; D006224:Cricetinae; D004307:Dose-Response Relationship, Radiation; D005333:Fetus; D008647:Mesocricetus; D013997:Time Factors; D014466:Ultraviolet Rays / Q000009:adverse effects*
chemical_list: D002110:Caffeine; D000099:Acetoxyacetylaminofluorene