Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P33527 (ABCC1)
 1,164 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To understand resistance to topoisomerase II inhibitors, we used four cancer cell lines (ZR-75B, MDA-MB-231, T47D, and MCF-7) and performed a single-step selection process to isolate 50 clones resistant to topoisomerase II inhibitors. Of these, 26 were isolated with VP-16 and 24 with mAMSA. Sixteen of these isolates (four from each cell line; two selected with VP-16 and two with mAMSA) were further exposed to higher drug concentrations. Characterization of the resistant sublines revealed the adaptation that occurs with increasing drug concentration during in-vitro selections. Reduced topoisomerase IIalpha mRNA level was observed in the majority of the initial isolates. This reduction was accompanied by a decrease in topoisomerase II activity. Other isolates showed increased levels of multidrug resistance-associated protein (MRP). With advancing resistance, MRP expression was increased further, concomitantly with some recovery in topoisomerase IIalpha expression and topoisomerase II activity. In these sublines, high levels of resistance were attained as a result of synergism between the reduced topoisomerase IIalpha levels and MRP overexpression. These results extend previous studies demonstrating how cellular adaptation to increasing drug pressure utilizes more than one mechanism. Reduced expression of topoisomerase IIalpha occurs early in the selection process. MRP overexpression can occur early or can help to confer high levels of resistance. In the latter case, MRP overexpression allows some recovery of topoisomerase II activity without loss of high drug resistance.
Jpn J Cancer Res 2001 Sep
PMID:Altered topoisomerase IIalpha and multidrug resistance-associated protein levels during drug selection: adaptations to increasing drug pressure. 1157 65

Drug resistance eventually occurs in most hematologic malignancies treated with chemotherapy. The mechanisms responsible for drug resistance include expression of transporters of xenobiotics of the adenosine triphosphate-binding cassette protein superfamily (P-glycoprotein, multidrug resistance associated proteins, breast cancer resistance protein), modifications of enzymes like deoxycytidine kinase, and defects in chemotherapy-induced apoptosis. The efforts to overcome this drug resistance have been focused, thus far, on modulation of P-glycoprotein. Several compounds were manufactured for this purpose, and phase III trials of PSC833, one of the most potent P-glycoprotein inhibitors, are completed. The emergence of modulators with several adenosine triphosphate-binding cassette protein targets, like GG120918 (inhibiting P-glycoprotein and breast cancer resistance protein) and VX710 (inhibiting P-glycoprotein and multidrug resistance associated protein 1), are of clinical interest in malignancies often expressing several efflux pumps simultaneously. Another approach is the use of "furtive" drugs like liposomal or nanoparticular anthracyclines.
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PMID:Drug resistance in hematologic malignancies. 1167 86

Cisplatin (DDP) is one of the key drugs used to treat patients with ovarian cancer, although resistance to DDP can occur. Paclitaxel and SN-38 (an active metabolite of irinotecan (CPT-11)) are two drugs that are effective in patients with DDP-resistant ovarian cancer. To study how these drugs may overcome the intrinsic and / or acquired resistance of cancer cells to DDP, we investigated the effect of a combination of DDP with paclitaxel and a combination of DDP with SN-38 on three ovarian cancer cell lines, RTSG (intrinsically resistant cell line), KF (DDP-sensitive cell line), and KFra (acquired resistant cell line obtained from KF). We found that these combinations showed additive to synergistic antitumor activity. A time-dependent platinum (Pt) accumulation was observed in the DDP-sensitive KF cell line, while a decrease occurred in the KFra cell line. Little accumulation was observed in RTSG. Intracellular Pt accumulation was increased in all three cell lines by exposure to paclitaxel or SN-38. Ouabain, a Na(+),K(+)-ATPase inhibitor, decreased Pt accumulation in KF and KFra cell lines and inhibited the paclitaxel- and SN-38-induced increases in Pt accumulation in these cell lines. When we assessed the mRNA levels of the multidrug resistance-associated protein (MRP), which may be an efflux pump for DDP, the combination of paclitaxel or SN-38 with DDP down-regulated these levels, which are up-regulated by DDP alone. These results suggest that paclitaxel and SN-38 overcome DDP resistance of ovarian cell lines by controlling intracellular accumulation of DDP via both the influx and efflux systems.
Jpn J Cancer Res 2001 Nov
PMID:Paclitaxel and SN-38 overcome cisplatin resistance of ovarian cancer cell lines by down-regulating the influx and efflux system of cisplatin. 1171 50

Anthranoid laxatives, belonging to the anthraquinones as do anthracyclines, possibly increase colorectal cancer risk. Anthracyclines interfere with topoisomerase II, intercalate DNA and are substrates for P-glycoprotein and multidrug resistance-associated protein 1. P-glycoprotein and multidrug resistance-associated protein 1 protect colonic epithelial cells against xenobiotics. The aim of this study was to analyse the interference of anthranoids with these natural defence mechanisms and the direct cytotoxicity of anthranoids in cancer cell lines expressing these mechanisms in varying combinations. A cytotoxicity profile of rhein, aloe emodin and danthron was established in related cell lines exhibiting different levels of topoisomerases, multidrug resistance-associated protein 1 and P-glycoprotein. Interaction of rhein with multidrug resistance-associated protein 1 was studied by carboxy fluorescein efflux and direct cytotoxicity by apoptosis induction. Rhein was less cytotoxic in the multidrug resistance-associated protein 1 overexpressing GLC4/ADR cell line compared to GLC4. Multidrug resistance-associated protein 1 inhibition with MK571 increased rhein cytotoxicity. Carboxy fluorescein efflux was blocked by rhein. No P-glycoprotein dependent rhein efflux was observed, nor was topoisomerase II responsible for reduced toxicity. Rhein induced apoptosis but did not intercalate DNA. Aloe emodin and danthron were no substrates for MDR mechanisms. Rhein is a substrate for multidrug resistance-associated protein 1 and induces apoptosis. It could therefore render the colonic epithelium sensitive to cytotoxic agents, apart from being toxic in itself.
Br J Cancer 2002 May 06
PMID:Cytotoxicity of rhein, the active metabolite of sennoside laxatives, is reduced by multidrug resistance-associated protein 1. 1198 86

The antiproliferative effects of bestatin and actinonin on U937 and K562 cells have been compared with their inhibitory activity on cell surface aminopeptidases. The results strongly suggest that the inhibition of cell surface aminopeptidases cannot be the main reason for the inhibition of cell proliferation. This was confirmed by studying the effect of buthionine sulfoximine (BSO), MK-571 (3-([[3-(2-[7-chloro-2-quinolinyl]-ethenyl)-phenyl]-[(3-dimethyl-amino-3-oxopropyl)-thio]-methyl]thio)propanoic acid) and verapamil on the inhibition of cell proliferation by bestatin and actinonin. BSO and MK-571, which inhibit the efflux of drugs mediated by multidrug resistance-associated protein (MRP), increased the action of both inhibitors, indicating that the latter enter the cells and that their export is mediated by MRP in both cell lines. Verapamil significantly increased the inhibitory activity of bestatin on K562 cells, indicating that the intracellular concentration of bestatin can be mediated also by P-glycoprotein.
Cancer Lett 2002 Aug 28
PMID:Aminopeptidase inhibitors bestatin and actinonin inhibit cell proliferation of myeloma cells predominantly by intracellular interactions. 1204 55

Multidrug resistance-associated protein 1 (MRP1) is a member of the ATP-binding cassette membrane transport superfamily and is responsible for multidrug resistance in cancer cells. Currently, there are nine known human MRPs. Distinct from many other members of the ATP-binding cassette superfamily, human MRP1 and four other MRPs have an additional membrane-spanning domain (MSD) with a putative extracellular amino terminus. The functional significance of this additional MSD (MSD1) is currently unknown. To understand the role of MSD1 in human MRP1 structure and function, we studied the amino-terminal 33 amino acids. We found that the amino terminus of human MRP1 has two cysteine residues (Cys(7) and Cys(32)) that are conserved among the five human MRPs that have MSD1. Mutation analyses of the two cysteines in human MRP1 revealed that the Cys(7) residue is critical for the MRP1-mediated drug resistance and leukotriene C(4) transport activity. On the other hand, mutation of Cys(32) reduced only moderately the MRP1 function. The effect of Cys(7) mutation on MRP1 activity appears to be due to the 5-7-fold decrease in the maximal transport rate V(max). We also found that mutation of Cys(7) changed the amino-terminal conformation of MRP1. This conformational change is likely responsible for the decrease in V(max) of LTC(4) transport mediated by the mutant MRP1. Based on these studies, we conclude that the amino terminus of human MRP1 is important and that the Cys(7) residue plays a critical role in maintaining the proper structure and function of human MRP1.
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PMID:Structural and functional consequences of mutating cysteine residues in the amino terminus of human multidrug resistance-associated protein 1. 1223 50

P-Glycoprotein and C-MOAT are important hepatic transport proteins which play a role in handling anticancer drugs. Hepatocellular carcinoma is a common hepatic malignancy that is relatively resistant to chemotherapeutic drugs. We therefore studied the expression of these two transport proteins in liver sections from hepatocellular carcinoma by immunohistochemistry and compared the reactivity to that in other liver conditions, including cirrhosis and dysplasia. We studied 53 sections from 17 liver specimens and found that the majority of samples stained positively for both P-glycoprotein and C-MOAT; however, the degree of staining was less in HCC and hepatic adenoma than in liver adjacent to HCC or in cirrhosis or dysplastic nodules. HCC with a compact pattern had less staining than those with acinar, scirrhous, or trabecular patterns. The location of both P-glycoprotein and C-MOAT staining was a function of the liver lesion present. Thus, most tissues without hepatocellular carcinoma showed foci of globular canalicular staining, whereas a delicate linear pattern of canalicular staining was most common overall. We conclude that expression of P-glycoprotein and C-MOAT, as detected by qualitative immunohistochemical evaluation are little affected by the development of HCC and therefore are probably of little clinical significance for management of malignancy.
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PMID:Expression of P-glycoprotein and C-MOAT in human hepatocellular carcinoma: detection by immunostaining. 1245 78

Multidrug resistance-associated protein 1 and P-glycoprotein are major ATP-binding cassette transporters that function as efflux pumps and confer resistance to a variety of structurally unrelated anticancer agents. To evaluate the comparative importance of these transporters with respect to anticancer agents, we established and characterized SV40-immortalized [mrp1(-/-)] (KO), [mdr1a/1b(-/-)] (DKO), and combined [mrp1 (-/-), mdr1a/1b(-/-)] (TKO) deficient fibroblast lines derived from primary embryonic fibroblasts of knockout mice. Western blot analyses demonstrated that KO and DKO fibroblasts exhibited similar levels of P-glycoprotein and mrp1, respectively, to that of wild-type (WT) fibroblasts. In addition, semiquantitative reverse transcription-PCR measurements of other multidrug resistance-associated protein (mrp) family members demonstrated that TKO fibroblasts displayed expression profiles of mrps 2-7 comparable to that of WT fibroblasts. These results indicate that loss of mrp1, P-glycoprotein, or both transporters does not cause overt compensatory changes in the expression of the other determined transporters. Using cell viability and calcein accumulation assays, we demonstrated that KO and DKO fibroblasts exhibited a low to moderate increase in sensitivity to vincristine and etoposide and in calcein accumulation compared to WT fibroblasts, whereas TKO fibroblasts displayed a markedly enhanced sensitivity to these agents and further elevated calcein accumulation. Furthermore, verapamil, an inhibitor of both mrp1 and P-glycoprotein, significantly sensitized WT fibroblasts to both vincristine and etoposide while having no effect on the sensitivity of TKO cells to these agents. Collectively, these findings indicate that mrp1 and P-glycoprotein are major determinants of drug sensitivity in immortalized mouse embryonic fibroblasts. They also suggest the existence of a compensatory mechanism by which the loss of one transporter can be functionally offset by the other in the transport of common drug substrates.
Mol Cancer Ther 2002 Oct
PMID:Comparative study of the importance of multidrug resistance-associated protein 1 and P-glycoprotein to drug sensitivity in immortalized mouse embryonic fibroblasts. 1248 34

Breast cancer resistance protein (BCRP/ABCG2) is a novel member of ATP- binding cassette transporters, which induce multidrug resistance in cancer cells. We found that a high level of BCRP expression in CD4+ T cells conferred cellular resistance to human immunodeficiency virus type-1 (HIV-1) nucleoside reverse transcriptase inhibitors. The cell line MT-4/DOX 500 was established through the long-term culture of MT-4 cells in the presence of doxorubicin (DOX) and had reduced sensitivity to not only DOX but also zidovudine (AZT). MT-4/DOX 500 cells showed reduced intracellular accumulation and retention of DOX and increased ATP-dependent rhodamine 123 efflux. The cells were also resistant to several anticancer agents such as mitoxantrone, 7-ethyl-10-[4-(1-piperidino)-1-piperidino]carbonyloxycamptothecin, and 7-ethyl-10-hydroxycamptothecin. AZT was 7.5-fold less inhibitory to HIV-1 replication in MT-4/DOX 500 cells than in MT-4 cells. Furthermore, the anti-HIV-1 activity of lamivudine was severely impaired in MT-4/DOX 500 cells. In contrast, the antiviral activity of non-nucleoside reverse transcriptase inhibitors and protease inhibitors was not affected in the cells. MT-4/DOX 500 cells expressed glycosylated BCRP but not P-glycoprotein (ABCB1), multidrug resistance protein 1, 2, or 4 (ABCC1, -2, or -4), or lung resistance-related protein. In addition, the BCRP-specific inhibitor fumitremorgin C completely abolished the resistance of MT-4/DOX 500 cells to AZT as well as to DOX. An analysis for intracellular metabolism of AZT suggests that the resistance is attributed to the increase of ATP-dependent efflux of its metabolites, presumably AZT 5'-monophosphate, in MT-4/DOX 500 cells.
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PMID:Breast cancer resistance protein (BCRP/ABCG2) induces cellular resistance to HIV-1 nucleoside reverse transcriptase inhibitors. 1248 37

The multidrug resistance-associated protein (MRP) subfamily transporters associated with anticancer drug efflux are attributed to the multidrug-resistance of cancer cells. The genomic organization of human multidrug resistance-associated protein 7 (MRP7) was identified. The human MRP7 gene, consisting of 22 exons and 21 introns, greatly differs from other members of the human MRP subfamily. A splicing variant of human MRP7, MRP7A, expressed in most human tissues, was also characterized. The 1.93-kb promoter region of MRP7 was isolated and shown to support luciferase activity at a level 4- to 5-fold greater than that of the SV40 promoter. Basal MRP7 gene expression was regulated by 2 regions in the 5'-flanking region at -1,780-1,287 bp, and at -611 to -208 bp. In Madin-Darby canine kidney (MDCK) cells, MRP7 promoter activity was increased by 226% by genotoxic 2-acetylaminofluorene and 347% by the histone deacetylase inhibitor, trichostatin A. The protein was expressed in the membrane fraction of transfected MDCK cells.
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PMID:Genomic structure, gene expression, and promoter analysis of human multidrug resistance-associated protein 7. 1256 91


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