Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:5.99.1.3 (topoisomerase)
 9,911 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human colorectal and pulmonary carcinomas have been shown to contain high levels of opioid peptides and their corresponding membrane-bound receptors. Therefore possible targeted drugs, consisting of modified enkephalins linked to cytotoxic drugs, were designed. Such conjugates were expected to be specifically internalized within opioid receptor-bearing cells. As a model to this approach, we have synthesized enkephalin-ellipticinium conjugates in which the D-Ala2-D-Leu5-enkephalin (DADLE) was coupled to the 2-nitrogen of either ellipticine or 9-hydroxyellipticine, two drugs acting through different mechanisms of cytotoxicity. These conjugates, DADLE-ellipticinium (NME) and DA-DLE-9-hydroxyellipticinium (NMHE), respectively, were previously shown to retain in vitro both opioid receptors and DNA affinities close to those of the parent compounds. In this paper, we first show that each individual moiety in the complexes remains capable of recognizing its cellular targets. Thus, pretreatment of NG108-15 cells containing delta-opioid receptors by the DADLE-ellipticinium conjugates induced a loss of opioid receptor (down-regulation), while the smaller peptide conjugates, tyrosinyl-D-alanylglycine-ellipticinium, prepared as control, do not. On the other hand, peptide-NMHE conjugates were able to induce DNA topoisomerase II-associated DNA strand breaks suggesting that they have a mode of action similar to that of their parent molecule, NMHE. We then examined whether or not these molecules could exert a specific toxicity on opioid receptor-bearing cells. However, when tested on NG108-15 tumor cells and L-fibroblasts as control, the enkephalin-ellipticinium conjugates (DADLE-NME and DADLE-NMHE) proved to be similarly more cytotoxic on both cell lines than their ellipticinium (NME and NMHE) precursors. In order to understand this apparent lack of specificity we examined the cellular accumulation and distribution of DADLE-NME by fluorescence techniques. These experiments revealed that an important intracellular overconcentration caused by a nonspecific process is probably masking the specific targeted effect of the conjugates. Hence, the project of linking DADLE to highly cytotoxic molecules which cannot cross the plasma membrane without site-directed targeting is discussed.
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PMID:Attempts to target antitumor drugs toward opioid receptor-rich mouse tumor cells with enkephalin-ellipticinium conjugates. 253 35

Ellipticine derivatives have been shown to induce DNA strand breaks by trapping DNA-topoisomerase II (Topo II) in an intermediary covalent complex between Topo II and DNA which could be related to their cytotoxic effects. We report here that Celiptium and Detalliptinium, two ellipticine derivatives clinically used for their antitumoral properties against breast cancer, exhibit the highest in vitro activity on Topo II DNA cleavage reaction and decatenation among a series of 14 ellipticine derivatives. The in vitro cleavage site specificity in pBR 322 plasmid DNA and in a human c-myc gene inserted in a lambda phage DNA is identical for both ellipticines, but different from m-AMSA, another Topo II related antitumoral agent. Recently, it has been shown that the ellipticine derivative Celiptium presents a strong cytotoxic activity in vitro on different human tumors including small cell lung carcinoma (SCLC). However, the studies that involved Topo II as a target for ellipticine derivatives have been performed only by using animal tumor cell lines. Therefore we have studied the in vivo DNA cleavage activity of Celiptium and Detalliptinium on a human SCLC cell line, NCI N417, comparatively to that obtained with m-AMSA. The respective IC50 on cell growth are 9, 8 and 1 microM for Celiptium, Detalliptinium and m-AMSA, respectively. Using the alkaline elution technique, we have observed that Celiptium and Detalliptinium exhibit a weak cleavage activity on genomic DNA from whole cells. The ellipticines are about 50 times less potent than m-AMSA in inducing DNA strand breaks. Analysis of in vivo c-myc gene cleavage by Southern blot hybridization also demonstrates a lack of activity of the ellipticine derivatives as no gene cleavage could be detected up to 50 microM of the drug. With m-AMSA, c-myc gene cleavage is detected at a concentration of 0.2 microM, which indicates that this methodology is less sensitive in detecting DNA strand breaks than is the alkaline elution. Further studies of the drug effect on isolated nuclei by alkaline elution also show that the DNA cleavage activity of Celiptium and Detalliptinium is increased when compared to whole cells. Our data indicate that these two drugs have a weaker cytotoxic effect than m-AMSA on NCI N417 cell line, due to a limited access to the cell nucleus rather than to a lack of activity on Topo II as assessed by in vitro and isolated nuclei experiments.
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PMID:Topoisomerase II-mediated DNA cleavage activity induced by ellipticines on the human tumor cell line N417. 254 83

Oxazolopyridocarbazole derivatives (OPCd) are intercalating polycyclic molecules related to the anti-tumor drug 9-hydroxyellipticinium (Celiptium). From a pharmacological point of view, OPCd compounds are highly cytotoxic to malignant cultured cells but inactive or only weakly active against experimental tumors in vivo. Extensive physicochemical and biological investigations have been performed in this series including the determination of hydrophobic properties, interaction parameters with DNA and polynucleotides, interaction with DNA topoisomerase II in vitro, diffusion through cell membranes, accessibility to genomic DNA in cells and in chromatin preparations and finally, cytotoxic and anti-tumor activities. Establishment of relationships between physicochemical data and biological properties have been attempted. The results show that all the OPCd compounds display favorable parameters in terms of association constant values to DNA, accessibility to DNA in chromatin structure and permeation through cellular membranes. However, in contrast with intercalating drugs such as m-AMSA, adriamycin and 9-hydroxyellipticinium, OPCd compounds are not able to generate cleavable complexes in DNA through the interaction with topoisomerase II. With respect to design of anti-tumor drugs, these findings indicate that a high association constant value to DNA, the ability to intercalate between DNA base pairs without causing physical damage and an efficient diffusion through cell membranes are not by themselves sufficient for the expression of anti-tumor activity.
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PMID:Relationships between physicochemical and biological properties in a series of oxazolopyridocarbazole derivatives (OPCd); comparison with related anti-tumor agents. 284 46

9-OH-Ellipticine (9-OH-E)-resistant cells are not only resistant to the DNA topoisomerase II inhibitors, but also to some other antitumor agents, such as actinomycin D (AD), adriamycin (ADM), daunorubicin and vincristine. It was previously shown that a decreased uptake accounts for the cross-resistance of these cells to AD and ADM which then suggested that the 9-OH-E-resistant cells might display some of the properties usually associated with the multidrug resistance phenotype. In this work, we have examined the effects of verapamil, a drug which is known to overcome the multidrug resistance, on the toxicity and the cellular accumulation of four cytotoxic agents: 9-OH-E, 2N-methyl-9-hydroxy-ellipticinium (NMHE), AD and ADM, either on 9-OH-E resistant cells or on a multidrug resistant subline derived from the same sensitive parental cells. Verapamil inhibited the cellular accumulation of the ellipticine derivatives in the sensitive DC-3F cells, and the toxicity of these drugs on these cells was correspondingly decreased. On either one of the resistant cell lines, verapamil had no effect on the toxicity and the cellular accumulation of 9-OH-E. In contrast, in the presence of verapamil, the cellular accumulation of NMHE by the 9-OH-E and the multidrug resistant cells was about 50% and 300% increased, respectively. The increased NMHE cellular concentration in the multidrug resistant cells was associated with an 8-fold increased toxicity. The major structural characteristics which might account for this difference between the sensitivities of both ellipticine derivatives to the effects of verapamil on the multidrug resistant cells is the presence of a positive charge on the nitrogen in position 2 of the 6H-pyridocarbazole molecule. Finally, verapamil circumvented partially the cross-resistance of DC-3F/9-OH-E cells to AD and ADM by increasing the accumulation of these drugs inside the cells.
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PMID:Effects of verapamil on the cellular accumulations and toxicity of several antitumor drugs in 9-hydroxy-ellipticine-resistant cells. 334 98

2-(Diethylamino-2-ethyl)9-hydroxyellipticinium-chloride, HCl (DHE), a new congener of the antitumor agent elliptinium acetate (Celiptium) (NMHE), has recently been selected for phase I clinical trials. NMHE has a methyl group at nitrogen 2 on the ellipticine ring while DHE possesses a basic diethylaminoethyl chain at this position. Compared to NMHE, the presence of the diethylaminoethyl side chain results in the following: a significant increase in the lipophilicity of the drug; no significant modification in either the binding constant values to DNA or the ability to intercalate between DNA base pairs; a marked decrease in the unwinding angle value of supercoiled DNA; and no significant change in the alteration of the catalytic activity of topoisomerase II in vitro. DHE appears to act as a simple reversible intercalating agent as shown by the selective mutagenic effect on Salmonella TA 1977 tester strain and by its inability to induce the SOS functions in a sfiA lac fusion containing Escherichia coli strain. From a pharmacological point of view, the presence of the diethylaminoethyl chain results in a 2-fold increase in the cytotoxicity to L1210 cultured cells, a strong increase in the antitumor efficiency on experimental murine tumors such as L1210 and P388 leukemia, B16 melanoma, M 5076 reticulosarcoma, and colon 38 adenocarcinoma, and finally an objective decrease in the acute and subacute toxicity in mice, rat, and macaque. The absence of significant differences in the interaction of NMHE and DHE with their potential targets in vitro leads to the hypothesis that the superiority of DHE in terms of cytotoxicity and antitumor efficiency may be due to an increase in the diffusion across cellular membrane and a more favorable biodistribution in vivo.
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PMID:Physicochemical and pharmacological properties of the antitumor ellipticine derivative 2-(diethylamino-2-ethyl)9-hydroxy ellipticinium-chloride, HCl. 367 74

Retroviral growth requires as an obligatory step the integration of a DNA copy of the viral RNA into the genomic DNA of the host. Recombinant human immunodeficiency virus type I (HIV-1) integrase (IN) expressed in Escherichia coli efficiently catalyzes the overall in vitro integration reaction, namely, the processing of the LTR ends and the strand transfer reaction. Using the 3' end of synthetic oligonucleotides which match the termini of the HIV-I U5 LTR as substrate and supercoiled pSP65 DNA as target, we have measured the effect of various topoisomerase inhibitors on the functional activity of the IN protein. Among the various drugs tested, the antitumor drug 2N-Methyl, 9-hydroxyellipticinium (NMHE) displays a marked inhibitory effect on the IN-catalyzed U5 insertion. This effect is related to the DNA binding properties of the drug rather than to a selective effect on the IN protein or the DNA-IN protein complex.
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PMID:Effect of topoisomerase inhibitors on the in vitro HIV DNA integration reaction. 838 50