Adjuvant chemotherapy is currently employed in the treatment of patients with
osteosarcoma, but the
drug regimens, although effective in improving disease-free survival, are unsuccessful in 20-40% of patients and very toxic. It would be useful to know whether
tumor cells are sensitive to a given
drug prior to its use. To this end, we developed a method of assessing
Adriamycin (
doxorubicin) binding to
tumor nuclei as a possible means of detecting sensitivity to the
drug.
Adriamycin-sensitive murine
osteosarcoma cells were used to develop the assay. The in vitro conditions (
drug concentration, duration of incubation, and temperature) were optimized with use of the murine
osteosarcoma cells in culture. After the cells had been incubated with
Adriamycin, cell viability was determined and
Adriamycin fluorescence intensity was measured with a cytofluorometer. The optimal parameters for
Adriamycin binding were found to be a 30-minute incubation in
a 10 micrograms/ml concentration of
Adriamycin at 37 degrees C; the frequency of cells that emitted
Adriamycin fluorescence from the nucleus compared with the total number of living cells reached 100% under these conditions. In a murine
leukemia cell line with known sensitivity to
Adriamycin, the cells emitted red fluorescence from the nucleus and cytoplasm, whereas in a resistant line the cells emitted
Adriamycin fluorescence from only the cytoplasm. We demonstrated that it is possible to differentiate nuclear from cytoplasmic concentration of
Adriamycin in a
tumor cell with use of a fluorescent microscope and that resistant cell lines can be distinguished from sensitive cell lines by this method.(ABSTRACT TRUNCATED AT 250 WORDS)