Enhancement of X-ray transformation by 12-O-tetradecanoyl-phorbol-13-acetate in a cloned line of C3H mouse embryo cells.

A phorbol ester promoting agent, 12-O-tetradecanoyl-phorbol-13-acetate, enhances X-ray transformation in vitro in a two-stage fashion similar to that shown previously for ultraviolet radiation and chemical carcinogens. In studies with a mouse embryo-derived cell line (C3H/1OT 1/2 clone 8), there were clear interactive effects between X-radiation and 12-O-tetradecanoylphorbol-13-acetate. These were particularly marked when a minimally transforming X-ray dose (50 or 100 rads) was followed by 12-O-tetradecanoylphorbol-13-acetate treatment beginning either immediately after the radiation exposure or 48 to 96 hr later.