Multidrug resistance of DNA-mediated transformants is linked to transfer of the human mdr1 gene.

Shen, Donglai; Fojo, Antonio Tito; Roninson, Igor B.; Chin, Janice E.; Soffir, R; Pastan, Ira; Gottesman, M M

doi:10.1128/mcb.6.11.4039

Cited by 140 publications

(50 citation statements)

References 17 publications

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“…Transfection of the mdrl gene into drug-sensitive clones confers drug resistance to cells that overexpress PGP (Debenham et al, 1986;Shen et al, 1986;Euda et al, 1987).…”

mentioning

confidence: 99%

Regulation of initial vinblastine influx by P-glycoprotein

Shalinsky

Jekunen²,

Alcaraz³

et al. 1993

Br J Cancer

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Summary P-glycoprotein (PGP) is an energy-dependent efflux pump that serves to protect cells against the cytotoxicity of many natural product drugs including vinblastine (VBL). In this study we investigated the role of PGP in regulating initial VBL influx. The apparent influx of VBL, measured over the first 20 s, was 2-fold lower in KB-GRCI cells expressing a transfected mdrl gene at high level than in non-expressing parental KB-3-1 cells. Inhibition of PGP efflux function with dipyridamole increased the influx rate constant by 4.0-fold in the KB-GRC1 cells but only 2.1-fold in the KB-3-1 cells. Verapamil, another inhibitor of PGP-mediated efflux, increased the initial influx rate constant by 2.7-fold in the KB-GRCI cells but only 1.4-fold in the KB-3-1 cells. Inhibition of PGP function by depletion of ATP increased influx by 6.8-fold and 2.2-fold in the two cell types, respectively. Mutation of PGP at both ATP binding sites abolished its ability to limit initial influx. Thus, VBL is serving as an efficient substrate for the efflux pump even within the first few seconds of drug exposure, consistent with the hypothesis that PGP may directly efflux drug from the cell membrane.

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“…Transfection of the mdrl gene into drug-sensitive clones confers drug resistance to cells that overexpress PGP (Debenham et al, 1986;Shen et al, 1986;Euda et al, 1987).…”

mentioning

confidence: 99%

Regulation of initial vinblastine influx by P-glycoprotein

Shalinsky

Jekunen²,

Alcaraz³

et al. 1993

Br J Cancer

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“…Independent transformation experiments with DNA from multidrug-resistant human or hamster cell lines consistently show transfer of only a subset of the P-glycoprotein genespecific DNA restriction fragments (5,23). This finding suggests that only a single P-glycoprotein gene family member is transferred and amplified.…”

Section: Discussionmentioning

confidence: 61%

Simultaneous expression of two P-glycoprotein genes in drug-sensitive Chinese hamster ovary cells.

et al. 1987

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Overexpression of P-glycoprotein is characteristic of multidrug-resistant cells. We analyzed four Pglycoprotein transcripts that are simultaneously expressed in a drug-sensitive Chinese hamster ovary cell line. We concluded that these transcripts are encoded by two distinct members of a P-glycoprotein multigene family, each of which has two alternative polyadenylation sites. A comparison of the two hamster sequences with the single reported human and mouse P-glycoprotein cDNA sequences demonstrates that P-glycoprotein is a highly conserved protein, that the hamster multigene family is undergoing concerted evolution, and that differences between gene family members are maintained across species. These conserved differences suggest that there may be functional differences between P-glycoprotein molecules.The presence of multidrug-resistant cells in human tumors and their selection and proliferation during chemotherapy may be major obstacles to cancer treatment (9). Mammalian cell lines selected for resistance to a single cytotoxic agent often develop pleiotropic resistance to unrelated drugs (9). Since many of the drugs involved are commonly used in chemotherapy, such cell lines have proven useful as in vitro models for the study of multidrug resistance in human tumors.A consistent alteration in multidrug-resistant cells is the overexpression of P-glycoprotein, an integral membrane protein of 170 kilodaltons (9). A P-glycoprotein cDNA clone, pCHP1 (19), has been isolated by using a P-glycoproteinspecific monoclonal antibody (14). This clone was used to isolate the cDNA clones discussed in this paper. Independently, an in-gel renaturation technique (20) has also been used to isolate amplified sequences from a drug-resistant hamster cell line (21). These sequences were used to isolate homologous human (2) and mouse (10) cDNA clones. The human cDNA sequence (mdrl) was reconstructed from several overlapping clones isolated from a multidrug-resistant cell line cDNA library. The mouse sequence was determined from a single full-length cDNA clone isolated from a drug-sensitive cell line. The human cDNA sequence (mdrl) encodes a protein detected by P-glycoprotein-specific monoclonal antibodies (26). We show that the human and mouse genes are homologs of different hamster P-glycoprotein (pgp) genes. We refer to the human and mouse mdr sequences as pgp genes in this communication to facilitate comparison of the P-glycoprotein genes across species.P-glycoprotein contains a tandem duplication in structure, with each half consisting of six transmembrane domains and a cytoplasmic domain containing the consensus sequences for an ATP-binding site (Fig.

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“…With help from the P mdr-1 probe it has also been possible to show that the mdr-1 gene containing DNA extracted from human multidrug resistant cells and subsequently transferred into drug-sensitive mouse cells induced multiresistance whereas cells that received DNA from human drug sensitive cells remained sensitive (47). This indicates that the human gene had to be expressed before the mouse cells could become drug resistant.…”

Section: Genetic Determinationmentioning

confidence: 91%