Accumulation of anthracenyl-amino acid topoisomerase I and II inhibitors in drug-sensitive and drug-resistant human ovarian cancer cell lines determined by high-performance liquid chromatography.

Anthracenyl amino acid/dipeptide conjugates (AADC) represent novel structures rationally designed for their DNA-binding properties. A high-performance liquid chromatography method is described for simultaneous determination of five compounds that exhibit novel mechanisms of action as topoisomerase I and II inhibitors. The method uses an Apex ODS-2 column and a mobile phase of 0.25 M ammonium acetate/trifluoroacetic acid (pH 3) in methanol with gradient elution. Selective detection is achieved by monitoring at 545 nm, with limits of detection ranging between 2 and 4 ng on the column. AADC are recovered from cell sonicates by solid-phase extraction using C2 cartridges, with extraction efficiencies ranging from 84% to 95%. Drug uptake studies were performed with three active compounds in the human ovarian cancer cell line A2780 and its multi-drug-resistant counterpart 2780AD. Marked differences were observed in the pattern of cellular accumulation produced by each compound. NU/ICRF 505 (tyrosine derivative) was taken up most avidly, reaching plateau levels of 4000 pmol/10(6) cells after 2 h, with no difference being apparent between A2780 and 2780AD. NU/ICRF 510 (arginine derivative) accumulated slowly in A2780, failing to achieve an equilibrium after 4 h, and appeared to be completely excluded from 2780AD. NU/ICRF 500 (serine derivative) was most rapidly taken up by A2780, producing a plateau of 800 pmol/10(6) cells after only 30 min with approximately 3-fold less accumulation in 2780AD. These results are correlated to the chemosensitivity of the two cell lines to the three compounds.