Saccharin is known to have a tumor-promoting effect on bladder cancer in rats, but its mechanism of action is unknown. We demonstrated that the increased agglutinability of isolated epithelial cells of the bladder in the presence of concanavalin A caused by a subcarcinogenic dose of bladder carcinogens disappeared shortly after the end of their administration. However, saccharin maintained the increased agglutinability when given continuously after administration of carcinogen. Moreover, the agglutinability of bladder cells previously exposed to a subcarcinogenic dose of bladder carcinogens increased again when saccharin was given after the agglutinability had disappeared completely.
Supported by Grants-in-Aid for Cancer Research from the Ministry of Education, Science and Culture, and the Ministry of Health and Welfare, Japan.