Analysis of Drug Transport Kinetics in Multidrug-resistant Cells: Implications for Drug Action

Abstract

Multidrug resistance (MDR) in model systems is known to be conferred by two different integral proteins--the 170-kDa P-glycoprotein (P-gp) and the 190-kDa multidrug resistance-associated protein (MRP1)--that pump drugs out of MDR cells. The intracellular level of a drug, which influences the drug's cytotoxic effect, is a function of the amount of drug transported inside the cell (influx) and the amount of drug expelled from the cell (efflux). One possible pharmacological approach to overcoming drug resistance is the use of specific inhibitors that enhance the cytotoxicity of known antineoplastic agents. Many compounds have been proven to be very efficient in inhibiting P-gp activity, but only some of them can inhibit MRP1. However, the clinical results obtained so far by this approach have been rather disappointing. The other likely approach is based on the design and synthesis of new non-cross-resistant drugs whose physicochemical properties favor the uptake of such drug by resistant cells. Our recent studies have shown that whereas the P-gp- and MRP1-mediated efflux of different anthracycline-based drugs may not differ considerably, their kinetics of uptake do. Thus, the high uptake of drug by cells may lead to concentrations at the cellular target site high enough to achieve the needed cytotoxicity against MDR cells. Therefore, increased drug lipophilicity might be one factor in improving drug cytotoxicity in MDR cells. In vitro studies have shown that idarubicin, an analogue of daunorub cin, is more effective than daunorubicin and doxorubicin against MDR tumor cell lines and that this increased effectiveness is related in part to the increased lipophilicity of idarubicin. Other studies have also confirmed the strong impact of lipophilicity on the uptake and retention of anthracyclines in MDR cells.

New insights into the P‐glycoprotein‐mediated effluxes of rhodamines

“…P-gp can transport neutral and positively charged molecules but not negatively charged ones. Despite the advances of recent years, we still have an unclear view of the molecular mechanism by which P-gp transports such a wide diversity of compounds across the membrane [5][6][7][8][9].Recently, we have performed several studies using K562 intact cells to describe the kinetics of anthracycline transport in MDR cells in order to predict how modifications in the anthracycline molecule affect its transport characteristics [10][11][12][13]. In the present paper we have used the same cell line to characterize the transport of several rhodamines.…”

“…P-gp can transport neutral and positively charged molecules but not negatively charged ones. Despite the advances of recent years, we still have an unclear view of the molecular mechanism by which P-gp transports such a wide diversity of compounds across the membrane [5][6][7][8][9].…”

Meloxicam increases intracellular accumulation of doxorubicin via downregulation of multidrug resistance-associated protein 1 (MRP1) in A549 cells

“…MDR is a major cause of cancer treatment failure when using cytostatic drugs (Mansilla et al, 2007) and the mechanism by which tumor cells acquire this drug resistance is probably through overexpression of membrane transport proteins that effectively efflux them (Garnier-Suillerot et al, 2001). The best-characterized mechanism of MDR is mediated through the overexpression of ABC transporter superfamily members, for example P-gp (MDR-1) and the multidrug resistant-associated protein (MRP-1) (Deeley and Cole, 2006).…”

“…These compounds, termed modulators or chemosensitizers, enhance the intracellular retention of anticancer drugs in MDR-1-overexpressing cells and thus circumvent drug resistance (Sikic, 1993). Unfortunately, in contrast to MDR-1-mediated resistance, MRP is affected by only a few agents (Garnier-Suillerot et al, 2001). However, the MDR-1 inhibitors, verapamil and cyclosporin A, have also been found to increase the accumulation of the MRP substrate, daunorubicin in drug-resistant cells (Lautier et al, 1996).…”

Antitumor activity of a membrane lytic peptide cyclized with a linker sensitive to membrane type 1-matrix metalloproteinase

“…This process can be completed in minutes at a micromolar level. As the potency does not rely on cellular internalization, lytic peptides circumvent the problems of multidrug resistance, which causes inefficient drug uptake and presents a predominant hindrance to conventional chemotherapy (13).…”