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Saquinavir induces stable and functional expression of the multidrug transporter P‐glycoprotein in human CD4 T‐lymphoblastoid CEM rev cells
Author(s) -
Dupuis ML,
Flego M,
Molinari A,
Cianfriglia M
Publication year - 2003
Publication title -
hiv medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.53
H-Index - 79
eISSN - 1468-1293
pISSN - 1464-2662
DOI - 10.1046/j.1468-1293.2003.00169.x
Subject(s) - saquinavir , p glycoprotein , lymphoblast , ritonavir , cell culture , indinavir , microbiology and biotechnology , medicine , pharmacology , protease , multiple drug resistance , biology , virology , virus , biochemistry , viral load , genetics , antiretroviral therapy , antibiotics , enzyme
Background The multidrug transporter P‐glycoprotein (P‐gp) is expressed in HIV‐1 target cells, in a range of pharmacological barriers and in AIDS‐associated tumours. P‐gp substrates include HIV‐1 protease inhibitors (PIs) and anticancer drugs, which are efficiently effluxed from multidrug‐resistant (MDR) cells. Objectives The aim of this study was to investigate the effect on human CD4 T‐lymphoblastoid CEM rev cells of saquinavir and other PIs in terms of P‐gp expression and to characterize the functional and biochemical patterns of PI‐induced P‐gp molecules. Methods CEM rev cells no longer expressing detectable amounts of P‐gp were cultured for a prolonged period in the presence of 10 μg/mL saquinavir (CEM saq10 ) and tested for P‐gp expression and function. Subsequently, CEM saq10 cells were transferred into medium containing 15 μg/mL saquinavir (CEM saq15 ) and cultured for several months. These cell lines were continuously monitored for P‐gp expression, function and immunochemical patterns. A similar strategy was adopted to determine whether other PIs, such as ritonavir and indinavir, were able to induce P‐gp expression in CEM rev cells. Results Compared with the drug‐diluent control, the exposure of CEM rev cells to 10μg/mL saquinavir induced, in a consistent fraction of cells (45–50%), de novo expression of functioning P‐gp molecules. The transfer of CEM saq10 cells to 15μg/mL saquinavir was associated with a dramatic increase in P‐gp expression and function (85–90% of CEM saq15 cells expressed P‐gp and effluxed P‐gp dye substrates). These saquinavir‐induced P‐gp molecules included 75‐kDa molecules as well as the classical 170‐kDa form of P‐gp, suggesting induction of a particular isoform of P‐gp termed mini ‐P‐glycoprotein. Conversely, ritonavir and indinavir induced transient P‐gp expression in a small percentage of the CEM rev cells. Conclusions Treatment of human CD4 T‐lymphoblastoid CEM rev cells with saquinavir caused over‐expression of functioning P‐gp molecules. This de novo acquired MDR phenotype, which differed from that induced by other PIs, was stable, as expression and activity of P‐gp were observed in CEM saq10 and CEM saq15 cells during prolonged in vitro culturing, even in drug‐free conditions.