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

Thirty human renal cell carcinomas and 94 non-small cell lung carcinomas of previously untreated patients were analyzed for the presence of P-glycoprotein, glutathione S-transferase-pi and topoisomerase II by means of immunohistochemistry. In the renal cell carcinomas investigated, two resistance markers were seen in 53% and three resistance markers in 36% of the cases. In only three tumors was one resistance mechanism observed. In the 94 non-small cell lung carcinomas 34% had two and 20% three resistance mechanisms, whereas 24% of the tumors revealed only one resistance mechanism. For determining the resistance of the tumors against drugs an in vitro short-term test was used. Only 12% of the sensitive lung tumors had more than one resistance mechanism, whereas 70% of the resistant tumors did. Thus a significant relationship exists between the resistance measured in vitro and the overexpression of P-glycoprotein or glutathione S-transferase-pi and the down-regulation of topoisomerase II.
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PMID:Expression of several resistance mechanisms in untreated human kidney and lung carcinomas. 135 30

Mechanisms of multidrug resistance were studied in murine leukemia (L 1210) and sarcoma (Sa 180) tumors after pretreatment with anthracyclines in vivo. Despite identical pretreatment protocols, a considerable difference in the level of resistance between L 1210 and Sa 180 tumors was noted (for doxorubicin: 45-fold versus 340-fold; for daunorubicin: 51-fold versus 275-fold). However, no difference in mdr 1 gene-amplification and the overexpression of mdr 1-RNA or P-glycoprotein was demonstrated. None of these parameters did increase by further treatment with a higher concentration of anthracyclines. Resistant sublines of Sa 180 revealed an overexpression of glutathione S-transferase-pi (GST-pi) in comparison to the parental line, whereas in sensitive and resistant sublines of L 1210 tumors the expression of GST-pi was similar. In order to study whether trifluoperazine can reverse the P-glycoprotein mediated component of multidrug resistance, trifluoperazine and doxorubicin were tested in vitro in L 1210 and Sa 180 cells. In contrast to the complete reversal of resistance in L 1210 tumors, resistance in Sa 180 was only partly circumvented. However, by buthionine sulfoximine treatment, the toxicity of multidrug resistant Sa 180 tumors could be increased. It was possible to reverse the resistance of Sa 180 tumors completely by trifluoperazine plus buthionine sulfoximine. Thus, multidrug-resistant Sa 180 tumors express different defense mechanisms whereas L 1210 tumors express only one defense mechanism (P-glycoprotein).
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PMID:Resistance mechanisms in murine tumors with acquired multidrug resistance. 144 88

Ninety-four human non-small cell lung carcinomas (NSCLC) of previously untreated patients were analysed for the presence of P-glycoprotein (P-170) and glutathione S-transferase-pi (GST-pi) by means of immunohistochemistry. The expression of P-170 and GST-pi was compared with the results of doxorubicin resistance of the tumours in vitro and the smoking habits of the patients. A significant relationship between smoking habits of the patients and resistance of NSCLC was found (P = 0.007). Of the 72 tumours of smokers 57 (= 79%) were resistant, whereas of the 22 tumours of non-smokers only 11 (= 50%) showed resistance. Identical results were obtained when the analysis was restricted to patients with epidermoid lung carcinomas (P = 0.004). In contrast to these data, there exists no relationship between resistance and smoking for adenocarcinomas of the lung. Forty-two (= 58%) out of the 72 NSCLC of smokers expressed P-170, whereas out of 22 tumours of non-smokers only two tumours (= 9%) showed P-170 expression (P less than 0.0001). Similar results were obtained with epidermoid carcinomas (P = 0.004) and adenocarcinomas (P = 0.027). Fifty (= 69%) of 72 NSCLC of smokers revealed expression of GST-pi, whereas only nine (= 41%) of 22 tumours of non-smokers showed GST-pi expression (P = 0.015). Significant correlations also exist between resistance in vitro and expression of P-170 (P less than 0.0001) or expression of GST-pi (P less than 0.0001). Furthermore, a significant relationship between both proteins could be demonstrated (P less than 0.0001).
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PMID:Overexpression of P-glycoprotein and glutathione S-transferase-pi in resistant non-small cell lung carcinomas of smokers. 168 Mar 67

In this report the effects of single doses of ionizing radiation on the mRNA expression of several proteins involved in multiple drug resistance were analyzed. Murine NIH 3T3 cells treated with single doses of 5, 10 and 20 Gy during the time interval from 1.5 to 72 h after irradiation were compared with their corresponding controls at the same points of time. The glutathione S-transferase-pi (GST pi) level was elevated in cells treated with 10 or 20 Gy from 24 to 72 h after irradiation compared with the control. Topoisomerase II alpha and thymidylate synthase were decreased in irradiated cells 24-72 h after exposure. These down-regulations were associated with cellular proliferation, determined by mRNA expression of the proliferation marker histone 3. Irradiated cells exhibited no alteration in the P-glycoprotein or glutathione peroxidase mRNA content. The finding that GST pi mRNA was overexpressed after irradiation was validated by investigations on a human lung carcinoma cell line (LXF 289) on the mRNA and protein level. Thus, our results indicate that irradiation alters the expression of proteins involved in multidrug resistance and may, therefore, play a role in clinical drug response.
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PMID:Effects of single doses of irradiation on the expression of resistance-related proteins in murine NIH 3T3 and human lung carcinoma cells. 755 53

Tumor tissues of untreated and cytostatic-agent-treated patients with nephroblastomas were investigated for expression of resistance-related proteins (P-glycoprotein, glutathione S-transferase-pi, glutathione peroxidase and topoisomerase II) to ascertain whether resistance proteins are changed after treatment. Tumor tissue was analyzed by means of mRNA. Twenty-three children were treated with actinomycin D and vincristine for 4 to 8 weeks. Eight children received no preoperative chemotherapy. In untreated patients, no expression of P-glycoprotein was seen, whereas, in the patients who were treated with actinomycin D and vincristine, 12 out of 23 tumors showed increased P-glycoprotein expression (> mean value). Although we found no difference between treated and untreated tumors for glutathione S-transferase-pi, we found significant differences in the expression of glutathione peroxidase. In the 8 untreated patients, 7 tumors showed low glutathione peroxidase (< mean value) and one high (> mean value) glutathione-peroxidase-mRNA content. With treatment, 11 tumors expressed low levels and 12 tumors high levels of mRNA. A significant positive correlation between P-glycoprotein and glutathione peroxidase was found. In addition, of the 8 untreated patients, 2 had low topoisomerase-II expression, and 6 high expression. With treatment, the expression was reduced in 18 tumors, and only 5 tumors had high levels of this protein. These results were confirmed by PCR and immunohistochemistry.
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PMID:Expression of resistance-related proteins in nephroblastoma after chemotherapy. 759 Dec 3

The aim of the study was to prove whether or not an association exists between the heat shock protein 70 (hsp70) and drug resistance. Tumor samples of 90 patients with previously untreated non-small lung carcinomas were investigated immunohistochemically for expression of resistance related proteins. Additionally, resistance to doxorubicin was determined using a short term test. No association between resistance related proteins. Additionally, resistance to doxorubicin was determined using a short term test. No association between resistance to doxorubicin and hsp70 was found. Of 63 resistant tumors, 33 showed low and 30 high hsp70 expression. Of the 26 sensitive tumors, 11 had low and 16 had high hsp70 expression. No relationship could be found between P-glycoprotein which is related to multidrug resistance and hsp70 expression or between hsp70 expression and expression of topoisomerase II, thymidylate synthase and metallothionein. On the other hand, a trend was noted for tumors with high glutathione S-transferase-pi expression to show high hsp70 expression. In addition, there was a significant relationship between hsp70 and catalase positivity. These data indicate that heat shock and stress promote intracellular oxidative damage and catalase is necessary for protection.
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PMID:Heat shock (hsp70) and resistance proteins in non-small cell lung carcinomas. 765 30

The expression of protein kinase C (PKC) in 83 untreated solid human non-small cell lung carcinomas was determined and its correlation with inherent resistance to doxorubicin, with the expression of P-glycoprotein (P-170), and with the expression of glutathione S-transferase-pi (GST-pi) was analysed. Doxorubicin resistance was measured using an in vitro short-term test. The expression of PKC, P-170 and GST-pi was assessed immunohistochemically. Twenty-three tumors (= 28%) were PKC-positive, whereas 60 tumors (= 72%) were PKC-negative. Nineteen tumors (= 23%) were classified as sensitive and 64 tumors (= 77%) as resistant to doxorubicin. Thirty-nine tumors (= 47%) were P-170-positive and 51 tumors (= 61%) GST-pi-positive. Out of the PKC-positive tumors, 21 were resistant to doxorubicin and 2 were sensitive. Of the same 23 tumors, 18 were P-170-positive and 19 were GST-pi-positive. The correlations between the expression of PKC and the resistance to doxorubicin, the expression of P-170 and the expression of GST-pi were statistically significant. Corresponding results were obtained comparing the results of all tumors with the results of a subgroup of tumors having the same histology (squamous cell carcinomas). This supports the hypothesis that PKC is involved in the inherent doxorubicin-resistance of human lung cancer.
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PMID:Associated expression of protein kinase C with resistance to doxorubicin in human lung cancer. 776 22

Acquired resistance to chemotherapeutic drugs by tumor cells is an important obstacle to effective therapy of human malignancy. These resistance cell lines originated from human or rodent have been characterized by increased expression of MDR (Multidrug-resistance) gene and P-glycoprotein which plays as efflux pump of drugs from cells. These multidrug-resistance sublines also have been reported increased activities of protein kinases and glutathione S-transferase-pi. Although there have been extensive biophysical and biochemical characterization of the differences between parental lines and MDR tumor cell sublines, morphologic observations have been limited. In this study, filamentous cytoskeletons which involve many biological phenomena such as maintenance of cell morphology, mitosis, cellular movement, transport, and adhesion, were observed by confocal laser microscopy. To compare the expression of each cytoskeletons, fluorescent intensities of cells stained for each cytoskeletons were measured by confocal laser microscopic system. Utilizing this methodology, higher microtubular expression was observed in HL-60/ADR and K562/ADR than in their parental lines, but no significant differences of actin and vimentin were observed. Phosphorylation by protein kinases has been established as a key factor in the regulation of cytoskeletal function. But little is known about the role of protein phosphorylation in cytoskeletal function. Since increased activities of PKC and PTK were detected in HL-60/ADR, the effect of PKC inhibitor, staurosporine (STR), or PTK inhibitor, genistein (GNS), on cell growth was detected. STR and GNS reduced the resistance to Adriamycin in HL-60/ADR. Furthermore, STR and GNS disrupted the filamentous structure of microtubules in HL-60/ADR, and suppressed the expression of microtubules to 37%, and 49%, respectively. In contrast, PKC activator, phorbol ester (TPA), caused stronger microtubular assembling in HL-60/ADR, and increased the expression of microtubules to 134%. Resulting from this study, it is likely that acquired MDR of HL-60 and K562 was associated with increased expression of microtubules, and microtubular assembling or disassembling was considered to be regulated in part by PKC and PTK.
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PMID:[Features of filamentous cytoskeletons in acquired multidrug-resistance of HL-60 human leukemia cell line]. 790 88

The expression of several resistance markers (P-glycoprotein, glutathione S-transferase-pi, thymidylate synthase, dihydrofolate reductase) was analyzed in matched primary tumors and lymph node metastases from 21 patients with lung cancer using immunohistochemistry. The analysis showed that expression of these resistance proteins is generally congruent in primary lung cancer and simultaneously resected lymph node metastases. This suggests that in general the resistance of a primary tumor predicts for the resistance of the metastases and vice versa.
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PMID:Detection of resistance proteins in matched primary lung tumors and lymph node metastases. 791 93

Relationships between the incidence of metastatic spread and microvessel density, expression of proto-oncogene products, or expression of resistance-related proteins were investigated in human ovarian carcinomas by immunohistochemistry. Ovarian carcinomas with a high microvessel density showed a significantly increased formation of metastases (P = 0.005). Tumors with positive immunoreactivity of c-jun and c-myc products had a higher metastatic spread; however, these results were not statistically significant. A marginally significant correlation existed between the expression of erbB1 (EGFR) and metastatic spread (P = 0.05). No significant relationship was found between the expression of the resistance-related proteins P-glycoprotein or glutathione S-transferase-pi and the incidence of metastases. Furthermore, no correlation was detected between expression of the heat shock protein 70 and the occurrence of metastases.
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PMID:Microvessel density, expression of proto-oncogenes, resistance-related proteins and incidence of metastases in primary ovarian carcinomas. 867 74


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