Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:5.99.1.2 (topoisomerase)
 9,166 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We investigated the mechanism of intrinsic resistance to cisplatin in human transitional cell cancer (TCC) using 7 human bladder cancer cell lines, which were derived from untreated TCC of the urinary bladder. The sensitivity to cisplatin was different from cell line to cell line, and a 15-fold difference was observed between the most sensitive line and the most resistant line. No significant correlation was observed between the content of intracellular glutathione and the resistance to cisplatin. In contrast, a positive correlation was seen between intracellular cisplatin accumulation and cisplatin resistance. The expression of drug resistance-related genes including glutathione S-transferase pi, gamma-glutamyl-cysteine synthetase, multidrug resistance-1, multidrug resistance-associated protein, DNA topoisomerase I, topoisomerase II, human canalicular multispecific organic anion transporter, and thioredoxin was not significantly related to cisplatin resistance. These data suggest that intracellular cisplatin may contribute to intrinsic cisplatin resistance and may therefore be a useful biomarker to predict cisplatin sensitivity in human untreated TCC.
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PMID:Accumulation of intracellular platinum is correlated with intrinsic cisplatin resistance in human bladder cancer cell lines. 1076 37

One hundred and fourteen kilobase pairs (kb) of contiguous genomic sequence have been determined immediately distal to the his5 genetic marker located about 0.9 Mb from the centromere on the long arm of Schizosaccharomyces pombe chromosome 2. The sequence is contained in overlapping cosmid clones c16H5, c12D12, c24C6 and c19G7, of which 20 kb are identical to previously reported sequence from clone c21H7. The remaining 93 781 bp of sequence contains 10 known genes (cdc14, cdm1, cps1, gpa1, msh2, pck2, rip1, rps30-2, sad1 and ubl1), 32 open reading frames (ORFs) capable of coding for proteins of at least 100 amino acid residues in length, one 5S rRNA gene, one tRNA(Pro) gene, one lone Tf1-type long terminal repeat (LTR) and one lone Tf2-type LTR. There is a density of one protein-coding gene per 2.2 kb and 22 of the 42 ORFs (52%) incorporate one or more introns. Twenty-one of the novel ORFs show sequence similarities which suggest functions of their products, including a cyclin C, a MADS box transcription factor, mad2-like protein, telomere binding protein, topoisomerase II-associated protein, ATP-dependent DEAH box RNA helicase, G10 protein, ubiquitin-activating e1-like enzyme, nucleoporin, prolyl-tRNA synthetase, peptidylprolyl isomerase, delta-1-pyrroline-5-carboxylate dehydrogenase, protein transport protein, coatomer epsilon, TCP-1 chaperonin, beta-subunit of 6-phosphofructokinase, aminodeoxychorismate lyase, a phosphate transport protein and a thioredoxin.
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PMID:Analysis of 114 kb of DNA sequence from fission yeast chromosome 2 immediately centromere-distal to his5. 1105 21

Of the bacterial topoisomerases, the gyrase A subunit (GyrA) of Staphylococcus aureus is particularly difficult to purify because of its tendency to form inclusion bodies. Previous attempts at purification yielded low concentrations of protein with reduced specific activity. To overcome this problem, we modified the commercially available plasmid expression vector, pBAD/Thio-TOPO, via the addition of DNA sequences encoding a hexahistidine tag upstream and a cleavage site for tobacco etch virus protease downstream of the gene encoding thioredoxin. The resulting expression system consisting of the modified plasmid, pSAGA7, and the recommended host strain, Escherichia coli TOP 10, facilitated high level expression of soluble GyrA and its affinity purification to over 95% homogeneity. Purified GyrA had high biological activity as evidenced by a specific activity of 4.3x10(5)U/mg. The pSAGA7/TOP10 expression system also facilitated the expression and purification of a subunit of S. aureus topoisomerase IV, ParE, and a recently discovered protein unrelated to topoisomerases, QnrB, two "hard to purify" proteins. We conclude that pSAGA7 might be useful for high-level soluble expression and purification of diverse microbial proteins.
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PMID:An improved expression plasmid for affinity purification of Staphylococcus aureus gyrase A subunit. 1628 15

The aim of this work was to determine the functional activities of four different antioxidative enzymes (glutathione reductase, glutathione-S-transferase, glutathione peroxidase, thioredoxin reductase) and the protein expression of three ATP-binding cassette transporters (P-glycoprotein, multidrug resistance protein 1, multidrug resistance protein 2) in a panel of 14 human cancer cell lines. Enzyme activities and transporter expression were then correlated with the in-vitro cytotoxic activities (GI50 values) of 19 standard antitumor drugs. Analogous data from the National Cancer Institute were used for comparison. The GI50 values of the platinum complexes, alkylating agents, antimetabolites, topoisomerase inhibitors and antimitotic drugs were determined by crystal violet or 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyl tetrazolium bromide assay. Standard enzymatic assays employed to measure the glutathione peroxidase, glutathione-S-transferase, glutathione reductase and thioredoxin reductase activities. The protein expression of the ATP-binding cassette transporter proteins was investigated by the Western-blot method. The delta method was used to normalize the data before bivariant correlation analysis. Only a few correlations between enzyme and cytotoxic activities of the antitumor agents were found. The GI50 values for melphalan and camptothecin correlated positively with the activity of glutathione-S-transferase, whereas GI50 values for methotrexate correlated positively with the cellular activities of both glutathione reductase and thioredoxin reductase. A significant correlation between glutathione reductase and thioredoxin reductase activities was found in our panel of cell lines. Neither P-glycoprotein nor multidrug resistance protein 2 expression could be detected by Western blot analysis in any cell lines investigated, but multidrug resistance protein 1 was consistently observed in all but four lines. Multidrug resistance protein 1 expression correlates positively with the GI50 values of several drugs, e.g. vinblastine and etoposide, and negatively with the GI50 values of 5-fluorouracil. The results confirm the complexity of resistance to antitumor agents and show that the GSH-thioredoxin system alone is not a good indication of intrinsic resistance for many of these anticancer drugs.
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PMID:Correlations between the activities of 19 standard anticancer agents, antioxidative enzyme activities and the expression of ATP-binding cassette transporters: comparison with the National Cancer Institute data. 1735 91