Differential transport properties of two mdr gene products are distinguished by progesterone.

Yang, Chia-Ping Huang; Cohen, Dalia; Greenberger, Lee M.; Hsu, Shu-Hui; Horwitz, Susan Band

doi:10.1016/s0021-9258(18)86944-7

Cited by 92 publications

(11 citation statements)

References 35 publications

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“…On the other hand, introduction of Thr at that site had very different effects on the activity of the three modulators. The effect of these mutations on the efficacy of these compounds was also dependent on the protein background onto which they were constructed (Table 1, mdrl vs mdr3), in agreement with previous results by Yang et al (1990), who observed preferential activity of PRG against mouse mdrl [mdrlb) over mdr3 (mdrla) encoded proteins.…”

Section: Discussionsupporting

confidence: 90%

Structurally Distinct MDR Modulators Show Specific Patterns of Reversal Against P-Glycoproteins Bearing Unique Mutations at Serine939/941

Kajiji¹,

Dreslin²,

Grizzuti³

et al. 1994

Biochemistry

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The mechanism by which P-glycoprotein (P-gp) interacts with a number of structurally unrelated substrates or inhibitors remains unknown. We have recently shown that a serine residue within the predicted transmembrane (TM) domain 11 of P-gps encoded by mouse mdr1 (Ser941) and mdr3 (Ser939) plays an important role in the substrate specificity of P-gp. We wished to determine if Ser939/941 is also important for efficient interaction of P-gp with structurally different modulating agents, a cyclic peptide (cyclosporin A, CsA), a diaminoquinazoline (CP100356), and a chiral, tricyclic structure (CP117227). For this, the capacity of these compounds to modulate the vinblastine (VBL) resistance phenotype of transfected cells expressing similar levels of P-gps bearing either the wild-type Ser or a mutant Phe at position 941 (mdr1) or 939 (mdr3) was initially tested. The Ser-->Phe substitution indeed affected the potency and P-gp isoform specificity of some of the modulators, in particular that of CP117227 (racemic mixture and enantiomers), which were active against wild-type but not mutant mdr3. The modulatory effect of the mutation on CP117227-mediated reversal of VBL resistance was parallelled by a comparable modulation of the steady-state levels of VBL accumulation in Ser939- and Phe939-expressing cells, but was not linked to differential cellular accumulation of the modulator, which was identical in both cell types. To further assess the role of this amino acid residue in P-gp interactions with modulators, the effect of additional mutations (Ala, Cys, Thr, Asp, Tyr, Trp) at that site on potencies of CsA, CP117227 enantiomers, and CP100356 was evaluated.(ABSTRACT TRUNCATED AT 250 WORDS)

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Section: Discussionsupporting

confidence: 90%

Structurally Distinct MDR Modulators Show Specific Patterns of Reversal Against P-Glycoproteins Bearing Unique Mutations at Serine939/941

Kajiji¹,

Dreslin²,

Grizzuti³

et al. 1994

Biochemistry

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“…The capacity of verapamil (VRP) and progesterone (PRG) to modulate the activity of wild-type and TM 11 mutant P-gps was tested. VRP and PRG treatments of P-gp expressing cells reverses their multidrug resistance phenotype by increasing intracellular drug accumulation (Tsuruo et al, 1981;Yang et al, 1989), possibly by competing for drug binding sites on P-gp (Cornwell et al, 1986;Yang et al, 1990;Safa, 1988;Qian & Beck, 1990;Naitoet al, 1989). The effect of VRP and PRG on theDsos of drug-sensitive control cells and cell clones expressing wildtype and mutant P-gps was determined in drug cytotoxicity assays and was expressed as a reversal factor (fold) calculated by comparison to the D$0 value in the absence of modulator (Tables II and III).…”

Section: Resultsmentioning

confidence: 99%

Functional analysis of P-glycoprotein mutants identifies predicted transmembrane domain 11 as a putative drug binding site

et al. 1993

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The substitution of a single serine to phenylalanine residue within the predicted transmembrane domain 11 of P-glycoproteins (P-gps) encoded by mouse mdr1 (Ser941, 1S;Phe941, 1F) or mdr3 (Ser939, 3S; Phe939, 3F) strongly modulates both the overall activity and substrate specificity of the two P-gps. In cell clones expressing either wild-type (1S, 3S) or mutant P-gps (1F, 3F), we show that the modulating effect of the mutation on the levels of adriamycin (ADM) resistance detected in drug cytotoxicity assays is paralleled by a similar modulation of the intracellular accumulation and extracellular efflux of radiolabeled adriamycin ([14C]ADM) from preloaded cells. Cytofluorescence studies with ADM on live cells produce similar results and demonstrate strong nuclear ADM accumulation only in drug-sensitive LR cells and in the 1F expressing cells, with little if any accumulation in 1S, 3S, or 3F expressing cells. Drug cytotoxicity and drug transport assays carried out in the presence of verapamil or progesterone suggest that the Ser to Phe substitution also reduces the capacity of these two reversal agents to modulate P-gp activity. Labeling experiments with the photoactivatable P-gp ligands iodoarylazidoprazosin and azidopine indicate a strong reduction in binding of these photoactivatable probes to the mutant P-gps (1F, 3F) as compared to their wild-type counterparts (1S,3S). These results indicate that the studied mutations in TM11 reduce drug transport by decreasing initial drug binding to P-gp. This phenotype is opposite to that of a mutation near TM3 in human MDR1 (pst 185), where decreased drug transport is associated with increased drug binding and decreased drug release from P-gp [Safa, A. R., Stern, R. K., Choi, K., Agresti, M., Tamai, I., Metha, N. D., & Roninson, I. B. (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 7225-7229].

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“…Since potential modulators evaluated in these assays would be used ultimately to revert MDR in human tumors positive for human MDR1 expression, it seemed appropriate to determine if functional differences with respect to interaction with modulators could be detected between the human and mouse isoforms. In addition, since we (Raymond et al, 1990) and others (Lothstein et al, 1989) have previously shown that the emergence of MDR in mouse cells (LTA, J774A, P388) can be asociated with the independent or simultaneous expression of mdrl and/or mdr3, it also seemed important to ask the same question for the two mouse isoforms in view of the previously reported differences in the modulating activity of progesterone (Yang et al, 1990) and other agents (Kajiji et al, 1993(Kajiji et al, , 1994a against the two mouse proteins.…”

Section: Discussionmentioning

confidence: 98%

“…Mouse mdr2 is expressed almost exclusively in liver bile canaliculi (Cordon-Cardo et al, 1990;van der Valk et al, 1990;Buschman et al, 1992), and the analysis of mutant mice carrying null alleles at this locus has suggested that although this P-gp does not transport MDR dmgs, it may transport phosphatidylcholine (Smit et al, 1993), working as a lipid translocase (Ruetz & Gros, 1994). In addition, P-gps encoded by mouse mdrl and mdr3 confer different degrees of resistance to structurally distinct MDR drugs (Kajiji et al, 1993) and seem to show different sensitivity to the reversal effect of structurally distinct inhibitors (Yang et al, 1990; Kajiji et al, 1994a). A similar comparison of functional similarities and differences between the mouse and human P-gps has been very difficult to carry out.…”

mentioning

confidence: 99%

Human (MDR1) and Mouse (mdr1,mdr3) P-glycoproteins Can Be Distinguished by Their Respective Drug Resistance Profiles and Sensitivity to Modulators

Tang‐Wai

Kajiji²,

DiCapua³

et al. 1995

Biochemistry

102

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Possible functional differences between P-glycoproteins (P-gps) encoded by the human MDR1 and mouse mdr1 and mdr3 genes with respect to drug resistance profiles and sensitivity to known modulators have been investigated. For this, the three genes were introduced and overexpressed in the same cellular background, that of Chinese hamster LR73 ovary cells, and drug-resistant clones expressing comparable amounts of the corresponding P-gps were selected under the same conditions. Analysis of the specific drug resistance profiles encoded by each P-gp for colchicine, adriamycin, vinblastine, and actinomycin D revealed overlapping but distinct patterns of drug resistance for the three isoforms. While all three P-gps conferred levels of resistance to vinblastine that did not vary by more than 2.5-fold, each isoform could be clearly distinguished by its capacity to confer resistance to colchicine and actinomycin D. Likewise, the study of structurally related and unrelated P-gp modulators indicated strong isoform-specific differences in the capacity of individual modulators to abrogate vinblastine resistance in the corresponding mdr transfectants. The study of several disubstituted piperazine analogs indicated that minor chemical modifications of the linker region of this modulator had strong effects on the sensitivity profile of each isoform to the modulator. Together, these results indicate that the three P-gp isoforms analyzed have specific and distinguishable functional characteristics with respect to interactions with drugs and modulators. These findings also suggest that P-gp positive murine transplantable tumors should be used with caution in the design and in vivo testing of novel P-gp modulators to be used to reverse multidrug resistance to tumor cells expressing human MDR1.

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Differential transport properties of two mdr gene products are distinguished by progesterone.

Cited by 92 publications

References 35 publications

Structurally Distinct MDR Modulators Show Specific Patterns of Reversal Against P-Glycoproteins Bearing Unique Mutations at Serine939/941

Structurally Distinct MDR Modulators Show Specific Patterns of Reversal Against P-Glycoproteins Bearing Unique Mutations at Serine939/941

Functional analysis of P-glycoprotein mutants identifies predicted transmembrane domain 11 as a putative drug binding site

Human (MDR1) and Mouse (mdr1,mdr3) P-glycoproteins Can Be Distinguished by Their Respective Drug Resistance Profiles and Sensitivity to Modulators

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