ENHANCED RESPONSE TO DAUNOMYCIN OF NORMAL, TUMOR AND METASTATIC CELL-LINES VIA DRUG PHOTOACTIVATION

We have compared the cytotoxicity of daunomycin in vitro to highly dif ferentiated normal epithelial cells (Fisher rat thyroid cells, FRTL-5) and to two neoplastic cell lines, a thyroid carcinoma (TK-6) and its lung metastasis (MPTK-6). Whereas the cell lines are equally sensitive to the drug in the dark, if irradiated during incubation with daunomy cin (86 J/CM2 at 488 nm), they become more and differently sensitive. Namely, the drug doses producing 50% mortality decrease by factors of about 22, 28 and 16 for FRTL-5, TK-6 and MPTK-6 cell lines, respective ly. This result correlates with differences in drug uptake and resista nce observed in the normal and neoplastic cell lines.