title: Taxane-based reversal agents modulate drug resistance mediated by P-glycoprotein, multidrug resistance protein, and breast cancer resistance protein.
abstract: Overexpression of ATP-binding cassette transport proteins, including P-glycoprotein (Pgp), multidrug resistance (MDR) protein (MRP-1), and breast cancer resistance protein (BCRP), is a well-characterized mechanism of MDR in tumor cells. Although the cytotoxic taxanes paclitaxel and docetaxel are substrates for Pgp-mediated efflux, the semisynthetic taxane analogue ortataxel inhibits drug efflux mediated by Pgp as well as, as we recently demonstrated, MRP-1 and BCRP. Nevertheless, ortataxel is not optimal for development as a clinical MDR modulator because of its cytotoxicity [corrected]. We sought to identify noncytotoxic taxane-based broad-spectrum modulators from a library of noncytotoxic taxane-based reversal agents (tRAs) designed by eliminating the C-13 side chain of the taxane molecule, which inhibits microtubule depolymerization. Twenty tRAs, selected based on modulation of paclitaxel cytotoxicity in Pgp-overexpressing MDA435/LCC6(mdr1) cells, were studied for modulation of retention and cytotoxicity of substrates of MRP-1 and BCRP as well as Pgp in established cell lines overexpressing each of these transporters. Four tRAs modulated MRP-1 and 17 modulated BCRP in addition to Pgp. The four broad-spectrum tRAs strongly modulated daunorubicin and mitoxantrone efflux and enhanced their cytotoxicity in cell lines overexpressing the three MDRs, decreasing IC(50) values by as much as 97% [corrected]. These tRAs, especially tRA 98006, have promise for development as clinical broad-spectrum MDR modulators and warrant more preclinical analysis to determine pharmacokinetic interactions and efficacy.
authors: Department of Pharmacology and Therapeutics and Leukemia Section, Department of Medicine, Roswell Park Cancer Institute, Buffalo, NY 14263, USA.
authors: Tracy A
authors: TA
authors: Brooks
authors: Hans
authors: H
authors: Minderman
authors: Kieran L
authors: KL
authors: O'Loughlin
authors: Paula
authors: P
authors: Pera
authors: Iwao
authors: I
authors: Ojima
authors: Maria R
authors: MR
authors: Baer
authors: Ralph J
authors: RJ
authors: Bernacki
authors: Tracy
authors: T
authors: Brooks
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism*; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000378:metabolism*; D001952:Bridged-Ring Compounds / Q000737:chemistry* / Q000494:pharmacology* / Q000633:toxicity; D016923:Cell Death / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D004353:Drug Evaluation, Preclinical; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D009363:Neoplasm Proteins / Q000378:metabolism*; D043823:Taxoids / Q000737:chemistry* / Q000494:pharmacology* / Q000633:toxicity
chemical_list: C116614:ABCG2 protein, human; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D001952:Bridged-Ring Compounds; D009363:Neoplasm Proteins; D043823:Taxoids; C080625:taxane