Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.6.3.44 (P-glycoprotein)
 13,344 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Feasibility of immunohistochemical staining of P-glycoprotein for the prediction of doxorubicin resistance in gastrointestinal cancers was examined. Among 10 cancer cell lines which consist of two gastric cancer cell lines and eight colon cancer cell lines, seven cell lines were stained positively by the monoclonal antibody to P-glycoprotein, C219. In consequence of the evaluation on the effect of doxorubicin on these tumour cells by means of succinic dehydrogenase inhibition test (SDI test), zero out of seven cell lines stained positively by C219 was sensitive to doxorubicin, but two out of three cell lines stained negatively were sensitive. Among 23 fresh surgical specimens of gastrointestinal cancers which consisted of 15 gastric cancers and eight colon cancers, seven tumour tissues were stained positively by C219. All P-glycoprotein positive tumours were resistant to doxorubicin. On the other hand, four of 16 P-glycoprotein tumours were sensitive to doxorubicin. These data indicate that positively stained cancer cells by C219 are resistant to doxorubicin.
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PMID:Prediction of doxorubicin resistance in gastrointestinal cancer by P-glycoprotein staining. 135 49

The expression of a multidrug-resistant (MDR) gene product, P-glycoprotein, was examined immunohistochemically in 41 transitional cell carcinomas (TCCs) of the urinary tract. In 23 of these, chemosensitivity to adriamycin (ADM) and vinblastine (VBL) was also assessed by a microtiter succinate dehydrogenase inhibition test and the correlation between the expression of P-glycoprotein and MDR phenotype was investigated. P-glycoprotein was detected in 13 (72.2%) of the 18 untreated TCCs of the upper urinary tract (UUT), 6 (31.6%) of the 19 untreated TCCs of the bladder, and all of the 4 TCCs treated with M-VAC chemotherapy, respectively. Fourteen (87.5%) of the 16 TCCs with a positive expression of P-glycoprotein were resistant to ADM and VBL, whereas all of the 4 TCCs sensitive to both drugs were negative in the expression of P-glycoprotein. The succinate dehydrogenase activity of TCCs with a positive expression of P-glycoprotein was significantly higher than that of TCCs with a negative expression of P-glycoprotein (P < 0.05). Thus, there was a good correlation between the expression of P-glycoprotein and MDR phenotype in the chemosensitivity test. These results suggest that intrinsic MDR exists in some TCCs of the urinary tract, particularly UUT, and that the immunohistochemical investigation of P-glycoprotein may be useful for predicting the MDR phenotype in TCCs of the urinary tract.
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PMID:Correlation between the expression of P-glycoprotein and multidrug-resistant phenotype in transitional cell carcinoma of the urinary tract. 136 55

In 58 human gastric cancers, the expression of P-glycoprotein (P-gp) was evaluated immunohistochemically and chemosensitivity was determined using the in vitro succinate dehydrogenase inhibition (SDI) test. Tumors which contained over 75% stained cells were scored as positive, and 14 of 58 cases (24%) were positive. There was no significant correlation between P-gp expression and clinicopathologic features. The succinate dehydrogenase (SD) activity for each drug of P-gp positive and negative tumors was as follows: 81.8 +/- 15.2% vs. 66.3 +/- 16.1% for Adriamycin (ADM), 75.5 +/- 14.2% vs. 59.1 +/- 17.6% for aclacinomycin A (ACR), 71.7 +/- 15.0% vs. 61.1 +/- 14.0% for mitomycin C (MMC), and 57.5 +/- 18.4% vs. 47.0 +/- 16.7% for cisplatin (CDDP). The increase in SD activity was evident in P-gp positive tumors compared with negative ones in cases of ADM (P = 0.0044), ACR (P = 0.0105), and MMC (P = 0.0353). We suggested that P-gp expression is closely related to chemosensitivities of human gastric cancers to anthracyclines.
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PMID:Expression of P-glycoprotein influences resistance against anthracyclines in clinical gastric carcinomas. 791 78

The expression of the multidrug-resistance gene product, P-glycoprotein was examined immunohistochemically in 31 untreated human renal cell carcinomas. In 17 of these, chemosensitivity to Adriamycin and vinblastine was also assessed by a microtiter succinate dehydrogenase inhibition test and the correlation between the expression of P-glycoprotein and intrinsic multidrug resistance was investigated. P-glycoprotein was detected in 16 (51.6%) of the 31 carcinomas. In the chemosensitivity test, 14 (82.4%) of the 17 carcinomas were estimated to be resistant to both drugs (multidrug resistant; MDR). Eight (72.7%) of the 11 carcinomas with a positive expression of P-glycoprotein were MDR, and none of them were sensitive of both drugs. On the other hand, MDR carcinomas were not necessarily associated with the expression of P-glycoprotein. Eight (61.5%) of the 13 MDR carcinomas showed a positive expression of P-glycoprotein while the remaining 5 (38.5%) were negative. These results suggest that the expression of P-glycoprotein is an important factor responsible for the intrinsic MDR phenotype of renal cell carcinoma, however, there are probably other factors involved as well which have yet to be fully elucidated.
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PMID:Expression of P-glycoprotein and multidrug resistance in renal cell carcinoma. 810 56

The expression of ATP-binding cassette superfamily transporter genes, such as P-glycoprotein/multidrug resistance (MDR) 1 and MDR protein (MRP) 1, is often up-regulated in various tumor types and is involved in responses to some anticancer chemotherapeutic agents. Five human MRP subfamily members (MRP2-6) with structural similarities to MRP1 have been identified. The relationships between MRP2-6 mRNA levels and drug resistance are not well understood. Data on 45 patients with colorectal cancer were analyzed. Of the ATP-binding cassette superfamily genes, we asked whether mRNA levels of MDR1, MRP1, MRP2, and MRP3 correlated with drug resistance to anticancer agents. For this analysis, we used quantitative reverse transcription-PCR, and the sensitivity to anticancer agents in surgically resected colon carcinomas was determined using the in vitro succinate dehydrogenase inhibition test. MDR1, MRP1, and MRP3 were highly expressed in normal colorectal mucosa, and the relative mRNA levels of MDR1, MRP1, and MRP3 in cancerous tissues compared with noncancerous tissues were decreased or unchanged. By contrast, MRP2 mRNA expression was low in normal colorectal mucosa and specifically increased in cancer regions compared with noncancerous regions. Of the anticancer agents prescribed for patients with colorectal cancers, including doxorubicin, mitomycin C, cisplatin, 5-fluorouracil, etoposide, and a camptothecin derivative, mRNA expression of MRP2 was significantly associated with resistance to cisplatin. MRP2 may be important for resistance to cisplatin treatment in colorectal cancer.
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PMID:Increased expression of an ATP-binding cassette superfamily transporter, multidrug resistance protein 2, in human colorectal carcinomas. 1087 92

Overexpression of the P-glycoprotein/multidrug resistance 1 (MDR1) and multidrug resistance protein 1 (MRP1) gene is closely associated with the clinical outcome of various malignancies, and it is involved in responses to some anticancer chemotherapeutic agents including doxorubicin. Six human MRP subfamily members (MRP2-7) with structural similarities to MRP1 have been identified. Recently, the relationships between MRP2 and MRP3 expression levels of some cancer cells and drug sensitivity to doxorubicin have been reported, but the relationship between the clinical samples and drug sensitivity remains unclear. We determined the expressions of the MDR1, MRP1, MRP2 and MRP3 gene in bladder cancer during the clinical course and sought to learn whether the expression was correlated with drug responses to doxorubicin. Doxorubicin, used in chemotherapeutic treatment including intravesical and systemic chemotherapy, is an important anticancer agent for the treatment of bladder cancer. We used quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) analysis for our study, and the sensitivity to doxorubicin in bladder cancer was determined using the in vitro succinate dehydrogenase inhibition test. Using 47 clinical samples of bladder cancer, we confirmed the significant correlation of MDR1, MRP1 and MRP3 mRNA levels with resistance to doxorubicin. We showed that the expression of MDR1, MRP1, MRP2 and MRP3 in recurrent tumors and residual tumors after chemotherapeutic treatment was higher than that in untreated primary tumors. In particular, the MDR1 expression in residual tumors was 5.7-fold higher than that in untreated primary tumors.
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PMID:Increased expression of multidrug resistance-associated proteins in bladder cancer during clinical course and drug resistance to doxorubicin. 1192 Jun 26

Background: We previously demonstrated that a Danshensu-Tetramethylpyrazine conjugate DT-010 enhanced anticancer effect of doxorubicin (Dox) in Dox-sensitive human breast cancer cells, and protected against Dox-induced cardiotoxicity. This work was designed to see whether DT-010 overcomes Dox resistance in resistant human breast cancer cells. Methods: The effects of DT-010, Dox or their combination on cell viability of Dox-resistant human breast cancer MCF-7/ADR cells were conducted using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Apoptosis was examined by flow cytometry after Annexin V-FITC/PI co-staining. Dox accumulation in MCF-7/ADR cells was detected by flow cytometry and fluorescence microscopy. A fluorometric multidrug resistance (MDR) assay kit was used to evaluate the effect of DT-010 on MDR transporter activity. P-glycoprotein (P-gp) expression and activity were analyzed by Western blot and rhodamine 123 (Rh123) efflux assay, respectively. The effects of DT-010 on glycolysis and mitochondrial stress were detected using an Extracellular Flux Analyzer. A Succinate Dehydrogenase Activity Assay kit was used to measure mitochondrial complex II activity. Results: At non-cytotoxic concentrations, DT-010 in combination with Dox led to a significant growth inhibition of MCF-7/ADR cells, suggesting a synergy between DT-010 and Dox to reverse Dox resistance. DT-010 restored Dox-mediated apoptosis and p53 induction in MCF-7/ADR cells. DT-010 increased Dox accumulation in MCF-7/ADR cells via inhibiting P-gp activity, but without changing P-gp expression. Further studies showed that DT-010 significantly inhibited glycolysis and mitochondrial function of MCF-7/ADR cells. Mitochondrial complex II activity was inhibited by DT-010 or DT-010/Dox combination, but not by Dox. The DT-010-mediated suppression of metabolic process may render cells more vulnerable to Dox treatment and thus result in enhanced efficacy. Conclusions: The results indicate that DT-010 overcomes Dox resistance in human breast cancer cells through a dual action via simultaneously inhibiting P-gp-mediated drug efflux and influencing metabolic process.
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PMID:A Danshensu-Tetramethylpyrazine Conjugate DT-010 Overcomes Multidrug Resistance in Human Breast Cancer. 3129 28