Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

An ethnobotanical survey of plants used to treat tropical ulcers in Papua New Guinea identified Lunasia amara as possessing anti-Staphylococcus aureus activity. Activity-guided fractionation of the aqueous bark extract resulted in the identification of the quinoline alkaloid lunacridine as the active principle. Lunacridine tends to cyslise at room temperature but the 2'-O-trifluoroacetyl derivative was found to be stable and therefore more suitable for biological assays. The compound exhibited a minimal inhibitory concentration (MIC) of 64 micro g/ml against Staphylococcus aureus NCTC 6571 and activity in the low micromolar range against HeLa and H226 cells; the latter showing signs of caspase-3/7 mediated apoptotic cell death. Experiments with drug resistant strains of Streptococcus pneumoniae suggested topoisomerase as a likely target for the drug in bacteria whilst decatenation assays with human topoisomerase II showed the compound to be a potent inhibitor of this isoform (IC(50)<5 micro M) thus explaining the drug's activity against human cell lines. Both lunacridine and 2'-O-trifluoroacetyl lunacridine exhibited mild DNA intercalation activity giving 50% decrease in ethidium DNA fluorescence at 0.22 and 0.6 mM, respectively, placing the drug amongst the DNA intercalating class of topoisomerase II inhibitors.
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PMID:Lunacridine from Lunasia amara is a DNA intercalating topoisomerase II inhibitor. 1696 12

A large number of hormones and local agonists activating guanine-binding protein-coupled receptors (GPCR) play a major role in cancer progression. Here, we characterize the new imidazo-pyrazine derivative BIM-46174, which acts as a selective inhibitor of heterotrimeric G-protein complex. BIM-46174 prevents the heterotrimeric G-protein signaling linked to several GPCRs mediating (a) cyclic AMP generation (Galphas), (b) calcium release (Galphaq), and (c) cancer cell invasion by Wnt-2 frizzled receptors and high-affinity neurotensin receptors (Galphao/i and Galphaq). BIM-46174 inhibits the growth of a large panel of human cancer cell lines, including anticancer drug-resistant cells. Exposure of cancer cells to BIM-46174 leads to caspase-3-dependent apoptosis and poly(ADP-ribose) polymerase cleavage. National Cancer Institute COMPARE analysis for BIM-46174 supports its novel pharmacologic profile compared with 12,000 anticancer agents. The growth rate of human tumor xenografts in athymic mice is significantly reduced after administration of BIM-46174 combined with either cisplatin, farnesyltransferase inhibitor, or topoisomerase inhibitors. Our data validate the feasibility of targeting heterotrimeric G-protein functions downstream the GPCRs to improve anticancer chemotherapy.
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PMID:Anticancer activity of BIM-46174, a new inhibitor of the heterotrimeric Galpha/Gbetagamma protein complex. 1698 67

Amrubicin, a completely synthetic 9-aminoanthracycline derivative, inhibits cell growth by stabilizing a topoisomerase II-DNA complex. This study was designed to examine the apoptosis induced in human leukemia U937 cells by amrubicin and its active metabolite amrubicinol. Amrubicin, amrubicinol and other antitumor agents, such as daunorubicin and etoposide, induced typical apoptosis with characteristic nuclear morphological change and DNA fragmentation. Measuring the population of sub-G(1) phase cells, it was found that under conditions where cell growth was inhibited by either amrubicin or amrubicinol, U937 cells underwent apoptotic cell death in a dose-dependent manner accompanied by an arrest of the cell cycle at G(2)/M. Furthermore, amrubicin- and amrubicinol-induced apoptosis was mediated by the activation of caspase-3/7, but not caspase-1, preceding a loss of mitochondrial membrane potential. These results indicate that both a reduction in mitochondrial membrane potential and the activation of caspase-3/7 are key events in the apoptosis induced by amrubicin and amrubicinol as well as the other antitumor agents. In addition, studies with oligomycin suggested that the apoptosis induced by amrubicin and amrubicinol involved substantially different pathways from that triggered by daunorubicin and etoposide. Oligomycin blocked the etoposide-induced increase in the number of sub-G(1) phase cells without preventing the activation of caspase-3/7, and had no inhibitory effect on the expansion of the sub-G(1) population in daunorubicin-treated cells, whereas apoptosis-related changes caused by amrubicin and amrubicinol were suppressed in the presence of oligomycin.
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PMID:Amrubicin induces apoptosis in human tumor cells mediated by the activation of caspase-3/7 preceding a loss of mitochondrial membrane potential. 1699 76

Etoposide (VP-16) is a topoisomerase II (topo II) inhibitor chemotherapeutic agent. Studies indicate that VP-16 enhances proinflammatory cytokines secretion from tumour cells, including IL-8, a chemokine associated with proangiogenic effects. Fluoroquinolones inhibit topo II activity in eukaryotic cells by a mechanism different from that of VP-16. The fluoroquinolone moxifloxacin (MXF) has pronounced anti-inflammatory effects in vitro and in vivo. We studied the effects of MXF and VP-16 on purified human topo II activity and further analysed their combined activity on proliferation, apoptosis and caspase-3 activity in THP-1 and Jurkat cells. Moxifloxacin alone slightly inhibited the activity of human topo II; however, in combination with VP-16 it led to a 73% reduction in enzyme activity. VP-16 inhibited cell proliferation in a time and dose-dependent manner. The addition of moxifloxacin for 72 h to low-dose VP-16 doubled its cytotoxic effect in THP-1 and Jurkat cells (1.8- and 2.6-fold decrease in cell proliferation, respectively) (P<0.004). Moxifloxacin given alone did not induce apoptosis but enhanced VP-16-induced apoptosis in THP-1 and Jurkat cells (1.8- and two-fold increase in annexin V positive cells and caspase-3 activity, respectively) (P<0.04). VP-16 induced the release of IL-8 in a time and dose-dependent manner from THP-1 cells. Moxifloxacin completely blocked the enhanced release of IL-8 induced by 0.5 and 1 microg ml(-1) VP-16, and decreased IL-8 release from cells incubated for 72 h with 3 microg ml(-1) VP-16 (P<0.001). VP-16 enhanced the release of IL-1beta and TNF-alpha from THP-1 cells, whereas the addition of MXF prevented the enhanced cytokine secretion (P<0.001). We conclude that MXF significantly enhances VP-16 cytotoxicity in tumour-derived cells while preventing VP-16-induced proinflammatory cytokine release. This unique combination may have clinical benefits and cytotoxic drug 'sparing effect' and should be further studied in vivo.
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PMID:Moxifloxacin enhances antiproliferative and apoptotic effects of etoposide but inhibits its proinflammatory effects in THP-1 and Jurkat cells. 1704 52

Caspase-3 is the ultimate executioner caspase that is essential for the nuclear changes associated with apoptosis. We investigated caspase-3 immunohistochemical expression in 58 primary intracranial meningiomas, using one monoclonal antibody detecting both precursor and cleaved caspase-3 (CPP32) and a second recognizing only the cleaved activated form (ASP175). Caspase-3 expression was analyzed in relation to baseline apoptosis-as illustrated by the expression of anti-single stranded DNA (ss-DNA), the antiapoptotic protein bcl-2, proliferation indices (Ki-67, PCNA, topoisomerase IIa, mitosin C), hormonal status (estrogen, progesterone, androgen receptors), standard clinicopathological parameters and patients' disease-free survival. Caspase-3 immunostaining was observed in 62% of cases for CPP32 and in 24% for ASP175. In both instances, the labeling index (LI) was significantly correlated with ss-DNA LI (p=0.038 and p=0.018). CPP32 but not ASP175 LI positively correlated with the mitotic index (p=0.001) and PCNA LI (p=0.004). Both CPP32 and ASP175 LIs were increased in nonbenign meningiomas (p<0.0001 and p=0.0035 respectively). In univariate and multivariate survival analyses, caspase-3 predicted meningioma recurrence, independently affecting disease-free survival (p=0.011 and p=0.047 respectively for CPP32; p<0.0001 and p=0.012 respectively for ASP175). Caspase-3 may prove to be a useful predictor of early recurrence in a group of neoplasms characterized by the frequent discordance between histology and clinical behavior.
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PMID:Caspase-3 immunohistochemical expression is a marker of apoptosis, increased grade and early recurrence in intracranial meningiomas. 1714 87

Anthracyclines and anthracenediones are well-known cancer chemotherapeutic agents but their uses are limited with cardiotoxicity and drug resistance. Several l- and d-form amino acids were introduced into the anthraquinone skeleton and numerous derivatives were synthesized for the evaluation of anticancer activity. The screening tests showed that WRC-213, an l-methionine conjugation, was the most effective derivative to inhibit proliferative effect of human androgen-independent prostate cancer PC-3 cells (IC50=50 nM). In an extension evaluation, WRC-213 displayed a potent anti-proliferative activity in various cancer cell lines, including non-small cell lung cancer A549, androgen-independent prostate cancer DU145, colorectal cancer HT-29, breast cancer MCF-7 and hepatocellular carcinoma Hep3B and HepG2. It induced cell-cycle arrest at S and G2, but not mitotic phase, in PC-3 cells. The comet assay revealed that induction of DNA damage and inhibition of topoisomerase II were the primary insults. After the checkpoint arrest of the cell-cycle, WRC-213 induced the mitochondria-mediated intrinsic apoptotic pathway, including Mcl-1 cleavage, Bcl-2 down-regulation and activation of caspase-9/caspase-3 cascades. Survivin degradation and caspase-2 activation also contributed to WRC-213-induced apoptosis. Moreover, the assessment of cytotoxicity in H9c2 cardiomyocytes and drug resistance in NCI/ADR-RES cells demonstrated that WRC-213 showed much lower cardiotoxicity and P-glycoprotein-related resistance than those of mitoxantrone, etoposide and doxorubicin. In conclusion, it is suggested that WRC-213 is a potential topoisomerase II inhibitor with reduced cardiotoxicity and drug resistance. It inhibits topoisomerase II activity and induces chromosomal DNA strand breaks, leading to S and G2 arrest of the cell-cycle and activation of mitochondria-mediated apoptotic pathways.
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PMID:WRC-213, an l-methionine-conjugated mitoxantrone derivative, displays anticancer activity with reduced cardiotoxicity and drug resistance: identification of topoisomerase II inhibition and apoptotic machinery in prostate cancers. 1803 33

9-anilinoacridine contains a tricyclic and planar aromatic structure that enables DNA intercalation and inhibition of topoisomerase II. Two recently developed sulfide derivatives of 9-anilinoacridines, 2-({4-[4-(acridin-9-ylamino)phenylthio]phenyl}(2-hydroxyethyl)amino)ethan-1-ol (CK0402) and 3-({4-[4-(acridin-9-ylamino)phenylthio]phenyl}(3-hydroxypropyl)amino)propan-1-ol (CK0403), displayed potent cytotoxic activity in multiple cancer cell lines. In-vitro enzymatic assay demonstrated that CK0402 and CK0403 directly inhibit decatenation reaction of topoisomerase IIalpha. Cells exposed to CK0403 showed DNA fragmentation, and activation of caspase-3 and caspase-2, indicating that it triggers caspase-dependent apoptosis. This was further supported by the fact that cytotoxicity of these drugs is attenuated by pharmacological inhibition of caspases with z-VAD-FMK. Studies with wild-type and p53 primary mouse embryonic fibroblasts demonstrated that p53 does not play a significant role in cell death process initiated by this kind of drug. In addition, pharmacological inhibition of poly(ADP-ribose) polymerase-1activity moderately enhanced cytotoxic activity of sulfide 9-anilinoacridine, suggesting that poly(ADP-ribose) polymerase-1 may have a protective function against 9-anilinoacridine-induced cell death process.
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PMID:Caspase-dependent cell death mediates potent cytotoxicity of sulfide derivatives of 9-anilinoacridine. 1845 48

Three derivatives of ouabain, digoxin and proscillaridin A containing the carboxylic group instead of the lactone moiety were synthesized and examined for cytotoxicity in human breast cancer cells. Evaluation of the cytotoxicity of these compounds employing an MTT assay and inhibition of [3H]thymidine incorporation into DNA in both MCF-7 and MDA-MB-231 breast cancer cells demonstrated that compound 3, the most active of the series, proved to be only slightly less potent than proscillaridin A. We evaluated the effects of these compounds 1-3 on change in intracellular Ca2+, appearance of apoptosis, inhibition of DNA topoisomerase I and II, and the activity of caspase-3 in breast cancer cells. These studies indicate that the increase in potency for 3 may be related, in part, to an activation of caspase-3, increasing free calcium concentration and topoisomerase II inhibition. All these data emphasize the potential usefulness of these derivatives of cardiac glycosides as anticancer agents.
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PMID:Antiproliferative activity of derivatives of ouabain, digoxin and proscillaridin A in human MCF-7 and MDA-MB-231 breast cancer cells. 1852 43

The Wilms' tumor 1 gene (WT1) encodes a transcription factor involved in cell growth and development. As we previously reported, WT1 expression is hardly detectable in normal hepatic tissue but is induced in liver cirrhosis. Although WT1 has been found to be overexpressed in a number of malignancies, the role of WT1 in hepatocarcinogenesis has not been clarified. We found that WT1 is expressed in several human hepatocellular carcinoma (HCC) cell lines, including PLC/PRF/5 and HepG2, and in HCC tumor tissue in 42% of patients. WT1 small interfering RNAs did not affect proliferation rate of HCC cells but abrogated their resistance to anoikis. Transcriptome analysis of PLC/PRF/5 cells after WT1 knockdown showed up-regulation of 251 genes and down-regulation of 321. Ninety percent of the former corresponded to metabolic genes, mostly those characterizing the mature hepatocyte phenotype. On the contrary, genes that decreased upon WT1 inhibition were mainly related to defense against apoptosis, cell cycle, and tumor progression. In agreement with these findings, WT1 expression increased the resistance of liver tumor cells to doxorubicin, a compound used to treat HCC. Interestingly, doxorubicin strongly enhanced WT1 expression in both HCC cells and normal human hepatocytes. Among different chemotherapeutics, induction of WT1 transcription was restricted to topoisomerase 2 inhibitors. When WT1 expression was prohibited, doxorubicin caused a marked increase in caspase-3 activation. In conclusion, WT1 is expressed in a substantial proportion of HCC contributing to tumor progression and resistance to chemotherapy, suggesting that WT1 may be an important target for HCC treatment.
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PMID:Wilms' tumor 1 gene expression in hepatocellular carcinoma promotes cell dedifferentiation and resistance to chemotherapy. 1919 Mar 40

Tissue transglutaminase (TG2) is a multifunctional member of the transglutaminase (TGase) family (E.C.2.3.2.13), which catalyzes in a calcium-dependent reaction the formation of covalent bonds between the gamma-carboxamide groups of peptide-bound glutamine residues and various primary amines. Here, we investigated the role of TG2 in a response of the neuroblastoma SH-SY5Y cells to topoisomerase II inhibitor etoposide, known to trigger DNA-damage cell response. We found an early and transient (approximately 2 h) increase of the TG2 protein in SH-SY5Y cells treated with etoposide, along with the increase of phosphorylated and total levels of the p53 protein. Next, we showed that SH-SY5Y cells, which overexpress wild-type TG2 were significantly protected against etoposide-induced cell death. The TG2 protective effect was associated only with the transamidation active form of TG2, because overexpression the wild-type TG2, but not its transamidation inactive C277S form, resulted in a pronounced suppression of caspase-3 activity as well as p53 phosphorylation during the etoposide-induced stress. In addition, exacerbation of cell death with a significant increase in caspase-3 and p53 activation was observed in SH/anti-TG2 cells, in which expression of the endogenous TG2 protein has been greatly reduced by the antisense cDNA construct. Though the cell signaling and molecular mechanisms of the TG2-driven suppression of the cell death machinery remain to be investigated, our findings strongly suggest that TG2 plays an active role in the response of neuroblastoma cells to DNA-damage-induced stress by exerting a strong protective effect, likely by the suppression of p53 activation and p53-driven cell signaling events.
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PMID:TG2 protects neuroblastoma cells against DNA-damage-induced stress, suppresses p53 activation. 2011 34


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