Table 1

Cross-resistance of DC-3F/S16 and DC-3F/9-OH-E cells to ellipticine derivatives

DC-3F IC501-aDC-3F/S16DC-3F/9-OH-E
IC501-aR1-bIC501-aR1-b
μM μM μM
S16020-20.030  ± 0.00712.4  ± 541312.5  ± 2.4415
S307610.045  ± 0.0024.0  ± 0.3905.7  ± 0.6127
9-OH-olivacine0.11  ± 0.040.47  ± 0.194ND1-c
NMHE0.80  ± 0.082.8  ± 0.033.5110  ± 20138
9-OH-E0.074  ± .0040.93  ± 0.11214.4  ± 1.3194

Drug toxicity was determined by the clonogenic assay after 3 h of drug exposure (see Materials and Methods).

    • ↵1-a  IC50, drug concentration inhibiting cloning efficiency by 50% as measured after 3 h of exposure to the drug by the colony formation assay.

    • ↵1-b  R, resistance factor was calculated as the ratio of IC50 values in DC-3F/S16:DC-3F or in DC-3F/9-OH-E:DC-3F.

    • ↵1-c  ND, not determined.