In vitro induction of ornithine decarboxylase in urinary bladder carcinoma cells.

The induction of ornithine decarboxylase by normal rat urine in bladder cancer cell cultures was tested in view of recent observations that urine acts as a tumor promoter. Addition of urine up to 15% in final concentration to culture medium resulted in a 10-fold increase in ornithine decarboxylase activity over the control. The stimulatory factor(s) contained in urine appears heat stable and may be multiple. 12-O-Tetradecanoylphorbol-13-acetate, a potent promoter in mouse skin carcinogenesis, induced a 39-fold increase in ornithine decarboxylase activity, the best response among the various substances tested. This suggests that it may act as a promoter of bladder cancer.