Cidal and subcidal effect of triethylene thiophosphoramide on cell kinetics of human bladder carcinoma cells in vitro.

In view of increasing topical use of various chemotherapeutic agents for bladder carcinoma, an experimental study concerning the effect of triethylene thiophosphoramide (Thio-Tepa) on cell kinetics of bladder carcinoma cells was performed, working on an established cell line of human bladder carcinoma. This polyfunctional alkylating agent, which is most widely used for instillation chemotherapy of bladder carcinoma, revealed a concentration dependent cytotoxicity against the cells. DNA precursor incorporation suggested that repair mechanism occurred following subcidal dose of this compound and faulty repair took place following cidal dose. The cell cycle was prolonged after subcidal treatment, the main effect being seen in DNA synthetic phase, and the changes in the cell cycle parameters returned to the normal within 2 cell cycle time. Repeated treatment with subcidal dose at an interval of 48 hr led to more extensive changes in the cell cycle as compared with that of single dose. Repeated exposures to subcidal dose, however, did not show any differences in the growth curves from those of the controls.