Table 1.

Drug sensitivity phenotype of MES-SA drug-resistant variants (fold resistance)

ClonesVinblastineDoxorubicinVP-16
Controls
MES-SA111
MES-SA/FS (MFS) *111
Drug Selected Variants
MES-SA/2B-E3 2153
MES-SA/3B-B9 563
MES-SA/10B-E2 863
MFS/VL20-4.1 70385
MFS/DS-5 §45510
MES-SA/DOX6D 422
MES-SA/VP6D 112
MES-SA/VP12D 224
Dx5 **2438042
  • NOTE: Fold resistance was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide cytotoxicity assay ( 6).

    Abbreviations: 6D, drug exposure for 6 d; 12D, drug exposure for 12 d.

  • * A subclone of MES-SA cells was isolated by limiting dilution method ( 9, 14).

  • DSMs of MES-SA cells were isolated via fluctuation analysis ( 6). Three representative clones of 13 populations are shown.

  • VSMs were derived from the MES-SA subclone cells (MFS; ref. 9). A representative clone of a population of eight is shown.

  • § MFS/DSM (80 nmol/L) cells were generated in this study. One representative clone of each selection is shown.

  • MES-SA cells were undergone with sublethal induction/selection by doxorubicin (40 nmol/L).

  • MES-SA cells were undergone with sublethal induction/selection by VP-16 (0.5 μmol/L).

  • ** Multistep doxorubicin-selected MDR cells from MES-SA cells ( 13).