Inhibition of Multidrug Resistance by AdamantylGb3, a Globotriaosylceramide Analog

Abstract

Multidrug resistance (MDR) via the ABC drug transporter (ABCB1), P-glycoprotein (P-gp/MDR1) overexpression, is a major obstacle in cancer chemotherapy. Many inhibitors reverse MDR but, like cyclosporin A (CsA), have significant toxicities. MDR1 is also a translocase that flips glucosylceramide inside the Golgi to enhance neutral glycosphingolipid (GSL) synthesis. We observed partial MDR1/globotriaosylceramide (Gb 3 ) cell surface co-localization, and GSL removal depleted cell surface MDR1. MDR1 may therefore interact with GSLs. AdamantylGb 3 , a water-soluble Gb 3 mimic, but not other GSL analogs, reversed MDR1-MDCK cell drug resistance. Cell surface MDR1 was up-regulated 1 h after treatment with CsA or adaGb 3 , but at 72 h, cell surface expression was lost. Intracellular MDR1 accumulated throughout, suggesting long term defects in plasma membrane MDR1 trafficking. AdaGb 3 or CsA rapidly reduced rhodamine 123 cellular efflux. MDR1 also mediates gastrointestinal epithelial drug efflux, restricting oral bioavailability. Vinblastine apical-to-basal transport in polarized human intestinal C2BBe1 cells was significantly increased when adaGb 3 was added to both sides, or to the apical side only, comparable with verapamil, a standard MDR1 inhibitor. Disulfide cross-linking of mutant MDR1s showed no binding of adaGb 3 to the MDR1 verapamil/cyclosporin-binding site between surface proximal helices of transmembrane segments (TM) 6 and TM7, but rather to an adjacent site nearer the center of TM6 and the TM7 extracellular face, i.e. close to the bilayer leaflet interface. Verotoxin-mediated Gb 3 endocytosis also upregulated total MDR1 and inhibited drug efflux. Thus, a functional interplay between membrane Gb 3 and MDR1 provides a more physiologically based approach to MDR1 regulation to increase the bioavailability of chemotherapeutic drugs. Multidrug resistance (MDR)3 is one of the major obstacles for successful chemotherapy in patients with cancer. The MDR phenotype has been associated with overexpression of P-glycoprotein in cancer cells (1). MDR1 is a 170-kDa plasma membrane glycoprotein that uses ATP to pump hydrophobic molecules out of the cell (2, 3). Its efflux function decreases drug concentration in tumor cells that results in chemotherapy failure. MDR1 is expressed in relatively high levels in the apical membranes of epithelial cells of intestine, kidney, liver, and blood-brain/testes barriers (4). Thus, the presence of MDR1 within the endothelial cells' epithelium can affect the bioavailability and the oral availability of therapeutic drugs (5).Various attempts have been made to reverse this resistance using MDR1 inhibitors that interact with MDR1 and block drug efflux. First generation modulators such as calcium channel blockers, calmodulin inhibitors, and cyclosporin were developed for pharmacological uses other than reversal of MDR and were relatively nonspecific and weak inhibitors that were also substrates of MDR1, and their deleterious toxicities with their use at required concentrations to inhibit MDR1 ...

Cisplatin-induced expression of Gb3 enables verotoxin-1 treatment of cisplatin resistance in malignant pleural mesothelioma cells

“…We could also correlate increased expression of Gb3 of cisplatin-resistant MPM and NSCLC cells to increased expression of MDR1/PgP. Gb3 and MDR1/PgP have recently been found to be partially co-localised in MDR1/PgPexpressing cells, and Gb3-containing lipid rafts are important for intracellular MDR1/PgP surface trafficking (De Rosa et al, 2008). The increased expression of MDR1/PgP in cisplatin resistance could, therefore, parallel increased Gb3 expression, as MDR1/PgP acts as a glycolipid translocase involved in the biosynthesis of glycolipids such as Gb3 (De Rosa et al, 2008).…”

“…Gb3 and MDR1/PgP have recently been found to be partially co-localised in MDR1/PgPexpressing cells, and Gb3-containing lipid rafts are important for intracellular MDR1/PgP surface trafficking (De Rosa et al, 2008). The increased expression of MDR1/PgP in cisplatin resistance could, therefore, parallel increased Gb3 expression, as MDR1/PgP acts as a glycolipid translocase involved in the biosynthesis of glycolipids such as Gb3 (De Rosa et al, 2008). However, we found also particularly of the Gb3-expressing fraction that was induced when the mother cell line was made cisplatin resistant.…”

“…MDR1/PgP acts as a glycolipid translocase involved in the biosynthesis of glycolipids such as Gb3, and elevated levels of Gb3 have also been seen in drug-resistant cancers, and functional interplay between membrane Gb3 and MDR1/PgP has been suggested (Lingwood et al, 1998;De Rosa et al, 2008). Gb3 functions as cell surface receptor for verotoxin-1 (VT-1, Shiga-like toxin-1) produced by pathogenic strains of Escherichia coli (Lingwood et al, 1987;Jacewicz et al, 1989;Rose and Clark, 1989).…”

Lipid Regulation of the ABCB1 and ABCG2 Multidrug Transporters

“…efflux, indicating that the lipid-binding site interferes with substrate binding (De Rosa et al, 2008). ABCB1 partially colocalizes with globotriaosylceramide at the cell surface, and glycosphingolipid depletion results in a decreased cell surface expression of ABCB1, indicating that gangliosides also influence the trafficking of this protein.…”

The overexpression of multidrug resistance-associated proteins and gankyrin contribute to arsenic trioxide resistance in liver and gastric cancer cells

“…In SGC7901/AS, only ABCB1 appeared to have significant expression at both the transcriptional and the translational level. Although there was no significant inhibition of growth in two arsenic-resistant cell lines with 20 μM verapamil, a standard ABCB1 inhibitor (26), two resistant cell lines partially restored the sensitivity of As 2 O 3 under 50 μM verapamil. The survival in the resistant group was still 10 to 20% higher than that in wild-type group.…”