Changes of cell cycle affecting cidal effect of triethylene thiophosphoramide on cultured human bladder carcinoma cells.

The cell cycle of the human bladder carcinoma cell line (MGH-U1 cells) was prolonged immediately after low dose of triethylene thiophosphoramide (Thio Tepa). Although the elongated cell cycle time seemed to return to the control level 48 hr following the treatment, there still remained postsynthetic accumulation and postmitotic diminution in the cell population and the cells were insensitive to high dose of the agent. The present results suggest that Thio Tepa is less effective for G2 cells, but more effective for G1 or S cells.