Intracellular adriamycin levels and cytotoxicity in adriamycin-sensitive and adriamycin-resistant P388 mouse leukemia cells.

Adriamycin (ADR) (NSC-123127) uptake and retention in ADR-sensitive P388 leukemia (P388/S) and ADR-resistant P388 leukemia (p388/R) cells were compared by fluorometry and laser flow cytometry (FCM) and were correlated with cytotoxic effects. Drug levels in P388/R cells treated in vitro with ADR (1-10 micrograms/ml) were twofold to fourfold lower than were levels in similarly treated P388/S cells FCM analysis of P388/S and P388/R cells exposed in vitro to ADR showed qualitative and quantitative differences in ADR fluorescence profiles of drug-treated cells (1-5 micrograms/ml) but not of the isolated nuclei (0.5- 10 micrograms/ml). Drug-induced perturbations in cell cycle traverse and chromosome aberrations were seen in P388/S but not in P388/R cells treated with 0.5-5 micrograms ADR/ml in vitro or 4-8 mg ADR/kg in vivo. The role of FCM in rapidly comparing and quantitating cellular ADR fluorescence profiles of ADR-sensitive and ADR-resistant tumors was demonstrated.