Killing effects of 5-fluorouracil on human biliary tract cancer cell lines

Data concerning the cellular sensitivity of human biliary tract cancer cell lines to 5-FU are scarce. The purpose of the present study was to evaluate the cellular sensitivity of Mz-ChA-2 (derived from gall bladder cancer) and SK-ChA-1 (derived from bile duct cancer) to 5-FU. The clonogenic capacity of these lines after pulse (1 h) or continuous (168 h) administration of various 5-FU concentrations (0.1-100 microg/ml) was evaluated in exponentially growing cells as well as in those that had reached the plateau phase. In both cell lines, exponentially growing cells were 1.8-times more susceptible to 5-FU than those in plateau phase. However, when cells in the same growth phase were compared, Mz-ChA-2 cells were 10 times more sensitive to the drug than SK-ChA-1 cells. Regardless of the growth phase or cell line, increasing the duration of exposure to 5-FU decreased the proportion of surviving cells. Even at a non-cytocidal dosage, exposing the cells for three doubling times markedly decreased the number of viable cells remaining after treatment.