title: The effect of fatty acids and analogues upon intracellular levels of doxorubicin in cells displaying P-glycoprotein mediated multidrug resistance.
abstract: Multidrug resistance mediated by overexpression of P-glycoprotein (P-gp) is a major obstacle in the chemotherapeutic management of cancer. The objectives of the current work were to examine if fatty acids affect the intracellular transport and dynamics of doxorubicin in drug-resistant cancer cell lines, and to assess if such effects were mediated through modulation of P-gp efflux pump activity. Among the range of fatty acids tested in this study, eicosapentaenoic acid diester (EPADI) increased doxorubicin accumulation [A] to 137% and retention [R] to 212% in doxorubicin-resistant MCF-7/ADR breast carcinoma cells, and [A] to 147% and [R] to 163% in vinblastine-resistant KBVI nasopharyngeal carcinoma cells. Consistent with EPADI-induced increases in intracellular doxorubicin concentrations, EPADI (10 microg/ml) sensitized MCF-7/ADR cells to the cytotoxic effects of doxorubicin (1 microg/ml) as assessed by MTT assay (viability < 50% of control), while EPADI itself displayed no cytotoxicity. The combination of EPADI (10 microg/ml) with verapamil (1 microM) resulted in a considerable increase in the [A] and [R] of the model P-gp substrate rhodamine-123 within drug-resistant cells compared to when either agent were used alone. KBV1 cells treated with combination of EPADI (10 microg/ml) and verapamil (1 microM) achieved 160% and 1120% greater [A] and [R] of rhodamine-123, respectively, compared to untreated cells. The P-gp modulatory effects of EPADI either alone, or as part of a combination with more potent inhibitors, should be further investigated.
authors.affiliation: Pharmaceutical Cell Biology, Welsh School of Pharmacy, Cardiff University, United Kingdom.
authors.forename: A N
authors.initials: AN
authors.lastname: Abulrob
authors.forename: M
authors.initials: M
authors.lastname: Mason
authors.forename: R
authors.initials: R
authors.lastname: Bryce
authors.forename: M
authors.initials: M
authors.lastname: Gumbleton
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000378:metabolism; D000903:Antibiotics, Antineoplastic / Q000493:pharmacokinetics* / Q000633:toxicity; D001693:Biological Transport, Active / Q000187:drug effects; D004317:Doxorubicin / Q000493:pharmacokinetics* / Q000633:toxicity; D018432:Drug Resistance, Multiple; D019008:Drug Resistance, Neoplasm; D004354:Drug Screening Assays, Antitumor; D004357:Drug Synergism; D015118:Eicosapentaenoic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology*; D006801:Humans; D020112:Rhodamine 123 / Q000493:pharmacokinetics; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000378:metabolism; D014700:Verapamil / Q000494:pharmacology
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000903:Antibiotics, Antineoplastic; D005231:Fatty Acids, Unsaturated; C419487:eicosapentaenoic acid diester; D020112:Rhodamine 123; D004317:Doxorubicin; D015118:Eicosapentaenoic Acid; D014700:Verapamil