ATP-dependent Transport of Rosuvastatin in Membrane Vesicles Expressing Breast Cancer Resistant Protein

A list of nonstandard abbreviations used in the paper: ABC, ATP-binding cassette Abstract MDR1/ABCB1, MRP2/ABCC2 and BCRP/ABCG2 are expressed in the liver and intestine and contribute to the disposition of many drugs. Rosuvastatin, an HMG-CoA reductase inhibitor for the treatment of patients with dyslipidemia, is primarily excreted via bile as unchanged drug. The present study was designed to determine if rosuvastatin is transported by MDR1, MRP2 and BCRP. The apparent permeability value for rosuvastatin across MDR1-MDCK cells was low (~ 8 nm/second) and no directional transport was observed. rosuvastatin uptake into control Sf9 membranes and membranes expressing MRP2 was similar in the presence or absence of GSH. In contrast, ATP dramatically stimulated rosuvastatin uptake into membranes expressing BCRP, but not control membranes. Rosuvastatin transport occurred into an osmotically sensitive space and was saturable. An Eadie-Hofstee analysis suggested that there were two transport sites in BCRP, with an apparent K m of 10.8 µM for the high affinity site and 307 µM for the low affinity site. These data demonstrate that rosuvastatin is transported efficiently by BCRP and suggest that BCRP plays a significant role in the disposition of rosuvastatin. This article has not been copyedited and formatted. The final version may differ from this version. DMD #007534 4 A number of ATP-binding cassette transporters (ABC) are expressed at the canalicular membranes of hepatocytes and the brush border membranes of enterocytes including the 1 P-glycoprotein (MDR1/ABCB1), the multidrug resistance protein 2 (MRP2/ABCC2), and the breast cancer resistance protein (BCRP/ABCG2) which is also known as the mitoxantrone resistance protein (MXR). These efflux transporters have distinct, but overlapping, substrate specificity and have been shown to be involved in biliary excretion of many drugs (Sasabe et al. which is overexpressed in resistant tumor cells, transports a wide variety of hydrophobic drugs such as daunorubicin, vinblastine, and loperamide (Hochman et al., 2002). MRP2 has been shown to transport many glutathione-S-, glucuronid-, and sulfate-conjugates. In addition to conjugates, MRP2 transports some unconjugated organic anions including methotrexate, irinotecan, and ampicillin (Gerk and Vore, 2002). The BCRP gene has been cloned and the protein product was found to be a half-transporter, consisting of a single 70 kDa, six-transmembrane peptide. Structurally diverse compounds such as anthracyclines, mitoxantrone, methotrexate, the camptothecins and estrone-3-sulfate have been identified as BCRP substrates (Sarkadi et al., 2004). Rosuvastatin is a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor for the treatment of patients with dyslipidemia. The …