pirarubicin and perimidine

Multidrug resistance of tumor cells is associated with the presence of membrane proteins responsible for the cytostatics export. Recently, we have synthesized a new family of benzoperimidines causing the futile cycle of MDR pumps. In this study, biological data for benzoperimidine esters are presented for selected cell lines: sensitive (HL-60, GLC4, K562), P-gp resistant (HL-60/VINC, K562/DX), MRP1 resistant (HL-60/DX) and MRP1/LRP resistant (GLC4/DX). Their ability to inhibit the efflux of anthracycline antitumor drug, pirarubicin and to restore its accumulation in MDR cells was studied using a spectrofluorometric method which allows to follow the uptake and efflux of fluorescent molecules by living cells. Benzoperimidine esters had high effectiveness in inhibiting pirarubicin efflux and in restoring its accumulation in resistant cells. In contrast, examined esters were less active in vitro in restoration of pirarubicin cytotoxicity towards resistant cells because an enzymatic cleavage of esters occurs in presence of serum esterases.

Topics: ATP Binding Cassette Transporter, Subfamily B, Member 1; Benzene Derivatives; Doxorubicin; Drug Resistance, Multiple; Humans; Immunosuppressive Agents; Quinazolines; Tumor Cells, Cultured

Multidrug resistance (MDR) phenotype in mammalian cells is often correlated with overexpression of P-glycoprotein or multidrug resistance-associated protein (MRP1). Both proteins are energy-dependent drug efflux pumps that efficiently reduce the intracellular accumulation and hence the cytotoxicity of many natural cytotoxins. The influx and efflux of drugs across the cell membrane are in large part responsible for their intracellular concentrations, and in the search for new compounds able to overcome MDR, it is of prime importance to determine the molecular parameters whose modification would lead to an increase in the kinetics of uptake and/or to a decrease in the pump-mediated efflux. Here, we studied three members of a new family of benzoperimidine antitumor compounds which exhibit comparable cytotoxicity towards resistant cells expressing P-glycoprotein, or MRP1, and sensitive cells. We used spectrofluorometric methods to determine the kinetics of the uptake and release of these three drugs in different cell lines: the erythroleukemia cell line K562 and the resistant K562/Adr expressing P-glycoprotein, the small-cell lung cancer cell line GLC4 and resistant GLC4/Adr expressing MRP1. We also studied, using confocal microscopy, the intracellular distribution of these drugs in NIH/3T3 cells. Our data show that (i) the kinetics for the uptake of these drugs is very rapid, higher than 2 x 10(-17) mole cell(-1) s(-1), (ii) the drugs are strongly accumulated in the nucleus and lysosomes, (iii) the three drugs are recognized and pumped out by both transporters, as shown by the inhibition of P-glycoprotein- and MRP1-mediated efflux of pirarubicin by benzoperimidine, with inhibitory constants of 1.5 and 2.1 microM for P-glycoprotein and MRP1, respectively, suggesting that benzoperimidine is transported by the two transporters with K(m) approximately 2 microM. In conclusion, the fast uptake kinetics of the benzoperimidines counterbalance their efflux by P-glycoprotein and MRP1.

Topics: 3T3 Cells; Animals; Antibiotics, Antineoplastic; Antineoplastic Agents; ATP Binding Cassette Transporter, Subfamily B, Member 1; Cell Nucleus; DNA; Doxorubicin; Drug Resistance, Multiple; Drug Screening Assays, Antitumor; Genes, MDR; Humans; K562 Cells; Lysosomes; Mice; Quinazolines