title: Reversal of multidrug resistance by tacrolimus hydrate.
abstract: Tacrolimus hydrate, a potent immunosuppressant produced by Streptomyces tsukubaensis, was examined for its effect on epirubicin activity in multidrug-resistant P388 leukemia (P388/R) cells overexpressing P-glycoprotein and the parent (P388/S) cells. In the absence of modulator, the 50% inhibitory concentration for epirubicin after 48-h incubation, determined using a microculture tetrazolium assay, was 0.8 microgram/ml in P388/R cells and 0.009 microgram/ml in P388/S cells. P388/R cells demonstrated a 90-fold reduction in sensitivity to epirubicin. Tacrolimus hydrate (1 and 10 microM) markedly enhanced epirubicin cytotoxicity by 4.2- and 26.7-fold for P388/R cells. A significant increase in LDH release from cells by tacrolimus hydrate was also observed in P388/R cells treated with epirubicin. Tacrolimus hydrate had a marked effect on epirubicin-induced G2/M blockade in the resistant cells. Both tacrolimus hydrate and cyclosporin A dramatically increased the accumulation of epirubicin by the resistant cells, while these compounds had no effect on epirubicin accumulation in the parent cells. Thus, tacrolimus hydrate is able to down-modulate P-glycoprotein-associated resistance through inhibition of P-glycoprotein function, suggesting that the drug may be a candidate for killing drug-resistant tumor cells.
authors.affiliation: Department of Pharmacology and Toxicology, Tohoku College of Pharmacy, Sendai, Japan.
authors.forename: J
authors.initials: J
authors.lastname: Wu
authors.forename: S
authors.initials: S
authors.lastname: Furusawa
authors.forename: S
authors.initials: S
authors.lastname: Nakano
authors.forename: M
authors.initials: M
authors.lastname: Takahashi
authors.forename: H
authors.initials: H
authors.lastname: Chiba
authors.forename: M
authors.initials: M
authors.lastname: Takayanagi
authors.forename: Y
authors.initials: Y
authors.lastname: Takayanagi
authors.forename: K
authors.initials: K
authors.lastname: Sasaki
mesh_terms: D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology*; D002453:Cell Cycle / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D016572:Cyclosporine / Q000494:pharmacology; D004347:Drug Interactions; D018432:Drug Resistance, Multiple; D019008:Drug Resistance, Neoplasm; D015251:Epirubicin / Q000494:pharmacology*; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D007941:Leukemia P388 / Q000188:drug therapy / Q000201:enzymology / Q000473:pathology*; D051379:Mice; D016559:Tacrolimus / Q000494:pharmacology*; D014407:Tumor Cells, Cultured / Q000166:cytology / Q000187:drug effects / Q000201:enzymology
chemical_list: D000903:Antibiotics, Antineoplastic; D007166:Immunosuppressive Agents; D015251:Epirubicin; D016572:Cyclosporine; D007770:L-Lactate Dehydrogenase; D016559:Tacrolimus