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)

We have characterised an etoposide-resistant subline of the small-cell lung cancer cell line, UMCC-1, derived at our centre. Subline UMCC-1/VP was developed by culturing the parent line in increasing concentrations of etoposide over 16 months. UMCC-1/VP is 20-fold resistant to etoposide by MTT assays, relative to the parent line, and is cross-resistant to doxorubicin, vincristine and actinomycin D, but not to taxol, cisplatin, melphalan, thiotepa or idarubicin. Topoisomerase II immunoblotting demonstrates a 50% reduction of the protein in the resistant subline. The UMCC-1/VP subline demonstrates a marked decrease in the accumulation of [3H]etoposide relative to the parent line, as well as a modest reduction in the accumulation of daunorubicin. Reverse transcription-polymerase chain reaction assays demonstrate no detectable mdr1 expression but marked expression of the multidrug resistance-associated protein (MRP) gene in the resistant subline. Northern blotting with an MRP cDNA probe confirms marked overexpression of the MRP gene only in the UMCC-1/VP subline. Western blotting with antisera against MRP peptide confirms a 195 kDa protein band in the UMCC-1/VP subline. Southern blotting experiments demonstrate a 10-fold amplification of the MRP gene in the resistant subline. Depletion of glutathione with buthionine sulphoximine sensitised UMCC-1/VP cells to daunorubicin and etoposide. Our studies indicate that MRP gene expression may be induced by etoposide and may lead to reduced accumulation of the drug.
Br J Cancer 1995 Sep
PMID:An etoposide-resistant lung cancer subline overexpresses the multidrug resistance-associated protein. 766 58

Multidrug resistance (MDR) in tumour cells is often caused by the overexpression of the plasma membrane drug transporter P-glycoprotein (P-gp) or the recently discovered multidrug resistance-associated protein (MRP). In this study we investigated the specificity and sensitivity of the fluorescent probes rhodamine 123 (R123), daunorubicin (DNR) and calcein acetoxymethyl ester (calcein-AM) in order to detect the function of the drug transporters P-gp and MRP, using flow cytometry. The effects of modulators on the accumulation and retention of these probes were compared in several pairs of sensitive and P-gp- as well as MRP-overexpressing cell lines. R123, in combination with the modulator PSC833, provided the most sensitive test for detecting P-gp-mediated resistance. Moreover, in a 60 min drug accumulation assay R123 can be regarded as a P-gp-specific probe, since R123 is not very efficiently effluxed by MRP. In contrast to R123, a 60 min DNR or calcein-AM accumulation test could be used to detect MRP-mediated resistance. The MRP-specific modulator genistein could be used in combination with DNR, but not with calcein-AM. Vincristine (VCR) can be used to increase the cellular uptake of calcein-AM in MDR cells, but is not specific for MRP. Thus, although the combination of DNR with genistein appeared to be as sensitive as the combination of calcein-AM with VCR, the former may be used to probe specific MRP activity whereas the latter provides a combined (P-gp + MRP) functional MDR parameter. With these functional assays the role and relative importance of P-gp and MRP can be studied in, for example, haematological malignancies.
Br J Cancer 1995 Sep
PMID:Functional detection of MDR1/P170 and MRP/P190-mediated multidrug resistance in tumour cells by flow cytometry. 766 59

We examined the levels of expression of the multidrug resistance-associated protein (MRP) gene quantified by Northern blot analysis in comparison with those of the MDR1 gene determined by reverse transcription-polymerase chain reaction (RT-PCR) in 104 non-small-cell lung cancer (NSCLC) specimens [59 adenocarcinoma (Ad), 40 squamous cell carcinoma (Sq), four large cell carcinoma (La) and one adeno-squamous carcinoma (AdSq)]. Thirty-three (31.7%) of the 104 NSCLC expressed the MRP gene at various levels. The NSCLC showing high (++) levels of MRP gene expression (19 out of 33, 57.6%) were predominantly squamous cell carcinomas (Ad, 5; Sq, 13; La, 1) (P < 0.05). Six of the eight NSCLCs expressing high levels of MRP mRNA and no MDR1 (MRP ++, MDR1-) were squamous cell carcinomas. Sixty-one of the 104 NSCLC patients received chemotherapy with MRP-related anti-cancer drugs [vindesine (VDS) and etoposide (VP-16)]. Twenty-three patients (37.7%) with tumour expressing high or moderate levels of MRP showed significantly worse prognoses than those with non- or low-MRP-expressing tumours (P < 0.05). These results suggest that the level of MRP gene expression is related to the histopathology and prognosis of NSCLC.
Br J Cancer 1995 Sep
PMID:Expression of the multidrug resistance-associated protein (MRP) gene in non-small-cell lung cancer. 766 60

We have generated rat and murine monoclonal antibodies against multidrug resistance-associated protein (MRP), a M(r) 180,000-195,000 membrane glycoprotein involved in a non-P-glycoprotein multidrug resistance of human tumor cells. The antibodies were raised against two different segments of MRP and found to be suitable for protein blot analyses, immunohistochemical and cytochemical studies, as well as flow cytometry of permeabilized cells. The antibodies do not cross-react with the human P-glycoproteins. Immunocytochemistry using MRP-overexpressing tumor cells of different histogenetic origins showed that MRP is predominantly located in the plasma membrane. Immunoelectron microscopy confirmed the plasma membrane location of MRP. The MRP antibodies provide a sensitive and specific tool for studies on MRP-mediated multidrug resistance.
Cancer Res 1994 Sep 01
PMID:Immunochemical detection of the multidrug resistance-associated protein MRP in human multidrug-resistant tumor cells by monoclonal antibodies. 791 28

The multidrug resistance-associated protein (MRP) gene is a member of the ATP-binding cassette transporter gene superfamily and may be partially responsible for clinical drug resistance. Reverse transcriptase-polymerase chain reaction was used to measure MRP mRNA in normal hematopoietic cells from bone marrow and peripheral blood as well as patients with high risk acute myelocytic leukemia and multiple myeloma. All normal peripheral blood cells, regardless of cell lineage (CD4, CD8, CD14, CD15, CD19, CD56), expressed a similar basal level of MRP mRNA. Specimens from bone marrow containing mixed lineages also expressed a similar basal level of MRP expression. In patients with acute myelocytic leukemia, 10 of 12 (83%) of the specimens had detectable MRP mRNA, but the level of expression was similar to that of normal blood cells and low compared to a cell line known to overexpress MRP (H69/AR). All myeloma patients (12 of 12) had detectable MRP mRNA expression at levels comparable to normal peripheral blood and bone marrow cells. We conclude that MRP is commonly expressed in normal hematopoietic cells as well as certain hematopoietic malignancies. The therapeutic relevance of MRP expression is unknown, but these studies emphasize the importance of measuring MRP expression in normal cells as a point of reference and comparison for detection in malignant cells. We also recommend obtaining sequential specimens from patients, which may reveal an increased expression of MRP from baseline as the disease progresses and becomes resistant.
Cancer Res 1994 Sep 01
PMID:Analysis of multidrug resistance-associated protein (MRP) messenger RNA in normal and malignant hematopoietic cells. 806 63

Studies of multidrug-resistant H69AR cells which overexpress the multidrug resistance-associated protein, compared with drug-sensitive parental H69 cells and revertant H69PR cells, revealed an inwardly rectifying K+ channel current (conductance, 231 pS/pF) and increased volume-regulated anion current (limiting conductance, 2 nS/pF). The anion current was selective for Cl- ions and sensitive to 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (0.1-1 mM) but ATP was not required for initial current activation even in excised patch experiments. K+ current reversal potential varied 52 mV/10-fold change in the external K+ concentration and current was blocked by BaCl2 (0.1-1 mM). The results indicate that overexpression of multidrug resistance-associated protein is accompanied by increases in both K+ channel and volume-regulated Cl- channel current in the multidrug-resistant cell line H69AR.
Cancer Res 1993 Sep 15
PMID:Inwardly rectifying K+ channels and volume-regulated anion channels in multidrug-resistant small cell lung cancer cells. 839 78

An active efflux pump for cis-diamminedichloroplatinum(II) (cisplatin) has been identified in cisplatin-resistant KCP-4 cells isolated from human epidermoid carcinoma KB-3-1 cells. The adenosine triphosphate(ATP)-dependent transport of leukotriene C4 (LTC4), an endogenous substrate for the glutathione S-conjugate export pump(GS-X pump), has been found in membrane vesicles prepared from KCP-4 cells. Multidrug resistance-associated protein (MRP) has also been identified as an ATP-dependent LTC4 transporter. To examine whether the GS-X pump expressed in KCP-4 cells in MRP, we investigated the expression of MRP in KCP-4 cells and compared the LTC4 transporting activity of GS-X pump expressed in KCP-4 cells with that of MRP. The level of MRP gene expression in KCP-4 cells was low and similar to that in KB-3-1 cells. MRP was not detected in membrane vesicles prepared from KB-3-1 and KCP-4 cells by immunoblot analysis. The ATP-dependent transport of LTC4 in KCP-4 and C-A120 vesicles showed saturable kinetics with an apparent Km of 0.18 microM and 0.25 microM, respectively. [3H]LTC4 transport in KCP-4 vesicles was more inhibited by 2,4-dinitrophenyl-S-glutathione(DNP-SG), bis-(glutathionato)-platinum(II) (GS-platinum) complex and glutathione disulfide(GS-SG) and less by LTD4 compared with that in C-A120 vesicles. The character of the LTC4 transporter expressed in KCP-4 vesicles is similar but not identical to that of MRP. Our results suggest that a glutathione S-conjugate export pump which is different from MRP exists in cisplatin-resistant KCP-4 cells.
Biochem Biophys Res Commun 1996 Sep 04
PMID:Characterization of the ATP-dependent LTC4 transporter in cisplatin-resistant human KB cells. 880 7

Human non-small-cell lung cancer (NSCLC) is considered to be a chemotherapy-refractory malignancy. The underlying mechanisms remain rather obscure. The multidrug resistance-associated protein (MRP), mediating a multidrug resistance (MDR) phenotype, has been reported to be overexpressed in several drug-selected lung cancer cell lines. A few previous studies have described intrinsic MRP expression in both NSCLC and normal lung tissues. However, the drug-transporting activity as well as the correlation with chemoresistance is unclear. Using 15 unselected cell lines, we show that MRP (mRNA and protein as detected by reverse transcriptase polymerase chain reaction and immunoblot) is frequently expressed intrinsically, with markedly varying intensity, in NSCLC. Two cell lines expressed high MRP levels, one comparable to the drug-selected controls (GLC4/ADR, HL-60/AR) without, however, amplification of the MRP gene (Southern hybridization). Using 3H-daunomycin (3H-DM) and calcein as MRP substrates and probenecid (PRO), genistein (GEN), benzbromarone (BB), N-ethylmaleimide (NEM) and verapamil (VP) as MRP modulators, drug accumulation studies revealed a transporting activity of MRP that correlated significantly with the gene expression data. Moreover, a significant correlation between MRP expression and chemoresistance against daunomycin (DM), doxorubicin (DOX), etoposide (VP-16) and vinblastine (VBL), but not cisplatin (CDDP) and bleomycin (Bleo) (MTT-based survival assay), was detected. Correlations mainly rested on the pronounced chemoresistance of 2 highly MRP-expressing cell lines and did not reach significance when these cell lines were excluded.
Int J Cancer 1997 Sep 26
PMID:Expression of the multidrug resistance-associated protein (MRP) and chemoresistance of human non-small-cell lung cancer cells. 933 14

Multidrug resistance (MDR) in human cancer cells is multifactorial. Previously, we reported on the association between expression of P-glycoprotein (Pgp), the multidrug resistance-associated protein (MRP), and the lung resistance protein (LRP) with the MDR phenotype in the NCI panel of 60 human cancer cell lines used for in vitro anticancer drug screening. Eight cell lines from this panel, manifesting widely divergent levels of in vitro drug resistance were chosen to investigate the role of MRP and LRP expression at the molecular level. LRP mRNA levels, as determined by ribonuclease protection assay, varied significantly among the 8 cell lines, and correlated closely with in vitro drug resistance to both MDR and non-MDR related drugs. LRP mRNA expression was determined to be a stronger correlate of drug sensitivity than protein expression. In contrast, MRP mRNA levels were not significantly correlated with drug sensitivity. The rates of newly transcribed LRP or MRP mRNA did not correlate with mRNA levels, indicating that mRNA stability or other features of processing may be important in regulation of LRP and MRP mRNA levels. Using Southern blot analysis, LRP gene amplification was shown not to be associated with LRP overexpression. These data suggest that LRP expression may be an important determinant of the MDR phenotype in cell lines intrinsically resistant to cancer chemotherapeutic agents.
Int J Cancer 1997 Sep 17
PMID:Increased LRP mRNA expression is associated with the MDR phenotype in intrinsically resistant human cancer cell lines. 937 36

The feasibility of combined studies on a cell-line panel and primary cultures of patient tumor cells in the preclinical evaluation of new anticancer drugs was evaluated in a study of the activity and cross-resistance pattern in vitro of the new semi-synthetic vinca alkaloid vinorelbine (Vrb). The activity of Vrb was investigated in ten cell lines representing different resistance mechanisms and in a total of 256 fresh human tumor samples, using the fluorometric microculture cytotoxicity assay (FMCA). Resistance to Vrb in the cell lines was associated with expression of the multidrug resistance-mediating P-glycoprotein and the multidrug resistance-associated protein (MRP) and by a recently described tubulin-associated mechanism, while the cell lines with topoisomerase II- and glutathion-associated resistance did not show decreased sensitivity to the drug. Cross-resistance to vincristine (Vcr) and other tubulin-active agents was high in cell lines as well as in patient cells. As with most commonly used anti-cancer drugs, Vrb was more active in hematological than in solid tumor samples. Among the solid tumors investigated, the highest in vitro response rates were observed in ovarian cancer (27%), sarcoma (25%), non-small cell lung cancer (21%) and bladder cancer (20%), while no response was observed in renal or colorectal cancer. Compared to Vcr, Vrb appeared to be slightly more active in solid tumors and slightly less active in hematological tumors. The results show that although Vrb displays a high degree of cross-resistance to Vcr and other tubulin-active drugs, some difference in the activity spectrum could be detected and that the drug is sensitive to multiple mechanisms of resistance. The results also suggest that leukemias, ovarian cancer, sarcoma and bladder cancer are possible further targets for Vrb. The combination of studies on a cell-line panel and patient tumor cells from a broad spectrum of diagnoses to evaluate a new drug seems feasible and may give information on the mechanism of action and target diagnoses for phase II trials.
J Exp Ther Oncol 1996 Sep
PMID:In vitro evaluation of new anticancer drugs, exemplified by vinorelbine, using the fluorometric microculture cytotoxicity assay on human tumor cell lines and patient biopsy cells. 941 16


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