Abstract
Most transformed and tumor cells rapidly take up fluorogenic fluorescein diacetate (FDA) only when they are viable, and become fluorescent because intracellular esterases generate fluorescein. When these cells were treated with the cytotoxic agents mitomycin C, neocarzinostatin, methotrexate, carboquone, cytosine arabinoside or UV-irradiation, they showed two pro-nounced changes within a short period : (a) suppression of the uptake of fluo-rescein diacetate shown by fluorescence intensity based on newly generated fluorescein and (b) change in the fluorescence polarization value (FP value), indicative of altered intracellular fluidity.
The degree of these two changes that occur shortly after drug treatment are either time or dose dependent and became apparent within one to several hours after treatment. One assay requires about 1 x 106 cells which usually generate about 2 pmol of fluorescein within 10 min at 30°C. The method is useful for rapid evaluation of cytotoxicity against tumor cells.
