Lethal and cytokinetic effects of anguidine on a human colon cancer cell line.

Anguidine is a fungal metabolite with antitumor activity in a murine colon cancer model. Because of disappointing results in clinical trials, we analyzed the lethal and cytokinetic effects of anguidine on cultured human colon cancer cells. The studies revealed a moderate reduction in survival only after prolonged drug exposure. Continuous incubation with anguidine for longer than 48 hr produced a moderate increase in the percentage of S-phase cells and a slight decrease in the proportion of cells in G1/0, by pulse cytophotometry. An immediate reduction in the cumulative labeling index for cells continuously exposed to tritiated thymidine and anguidine and a rapid decrease in the cumulative mitotic index for cells continuously exposed to Colcemid and anguidine indicated a block at the G1 into S and G2 into mitosis transitions. Tumoricidal activity of anguidine in a cultured human colon cancer line is poor and requires prolonged exposure. The kinetic data reflect an almost frozen state of the cell cycle.