Drug | IC50 | Resistance factor | |||
---|---|---|---|---|---|
Topoisomerase II inhibition | Cell growth inhibition | ||||
Human p170 topoisomerase II | CHO nuclear extract topoisomerase II | CHO | DZR | ||
μm | |||||
Mitindomide | 200 ± 50 (5) | 150 ± 50 (3) | 69 ± 12 (5) | 2,100 ± 1,000 (3) | 30 |
Dexrazoxane | 9.3 ± 2.7 (4) | 6.2 ± 1.81-a | 5.8 ± 2.1 (4) | 2,900 ± 190 (4) | 500 |
ICRF-1931-b | 0.6 | N.D. | 0.017 | 0.3 | 18 |
Topoisomerase II inhibition was measured with a gel assay using catenated kDNA as a substrate as described in Materials and Methods. Cell growth inhibition was measured in 96-well plates using an MTT assay after the cells had been incubated with the drug for 72 hr. Values reported are the means ± standard error; the numbers in parentheses are the number of separate determinations carried out on different days.