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At least 19 recordsLinked to original sources
PubMed2003

Rat microsomes activating the anticancer drug ellipticine to species covalently binding to deoxyguanosine in DNA are a suitable model mimicking ellipticine bioactivation in humans.

Ellipticine is a potent antineoplastic agent, whose mode of action is considered to be based mainly on DNA intercalation and/or inhibition of topoisomerase II. Recently, we found that ellipticine also forms covalent DNA adducts and that the formation of the major adduct is dependent on the activation of ellipticine by cytochrome P450 (P450). We examined rat, rabbit, and human hepatic microsomal samples for their ability to activate ellipticine. The extent of activation was determined by binding of 3H-labeled ellipticine to DNA and by analyzing DNA adducts by 32P-postlabeling. We demonstrate that cytochrome P450 of human hepatic microsomes activating ellipticine to species binding to DNA is analogous to that of rats, but not of rabbits. Most of the ellipticine activation in rat and human hepatic microsomes is attributed to P450 enzymes of the same subfamily, P450 3A1/2 and P450 3A4, respectively, while the orthologous enzyme in rabbit hepatic microsomes, P450 3A6, is much less efficient. With purified enzymes, the major role of P450 3A1 and 3A4 in ellipticine-DNA adduct formation was confirmed. We identified deoxyguanosine as the target for P450-mediated ellipticine binding to DNA using polydeoxyribonucleotides and deoxyguanosine 3'-monophosphate. The results strongly suggest that rats are more suitable models than rabbits mimicking the metabolic activation of ellipticine in humans.

Animals↗
PubMed1982

[Syntheses designed to produce 8-amino ellipticine. Synthesis and pharmacological properties of 8-nitro ellipticine].

The synthesis of 8-nitro ellipticine starting from 6-nitro indole is reported. It is the first derivative of ellipticine substituted in position 8 obtained by total synthesis. In contrast to 9-nitro ellipticine the 8-nitro derivative could until now not be reduced to 8-amino ellipticine. To obtain the latter it was intended to arylate an enamine of the 2,5,8-trimethyloctahydroisoquinolone-6 by 1-chloro 2,4-dinitrobenzene, followed by a reductive cyclization and N-demethylating aromatization. Since the yield of the arylation step was low, the isoquinolone was replaced by 2,5-dimethyl cyclohexanone and the synthesis would have to be completed by addition of a pyridine ring. In the case the yield of the aromatisation was 37%, but the carbazole derivative resisted all formylation attempts. 8-Nitro ellipticine was investigated for its DNA affinity, its cytotoxic activity on L 1210 tumors cells and its toxicity in the mouse. The results obtained were compared with those for 9-nitro ellipticine and in regard to cytotoxicity, with those for the 8- and 9-hydroxy ellipticines.

Alkaloids↗
PubMedDate not supplied

Effects of BD-40, an ellipticine analogue (aza-ellipticine) on cell cycle traverse and DNA synthesis in cultures of synchronized mouse fibroblasts.

BD-40 is a pyrido-pyrrolo-isoquinoline analogue of ellipticine, which possesses oncostatic in vivo activity on experimental tumors, and dose-dependent cytostatic and cytotoxic activities on mammalian cells in culture. In order to appreciate the effects of the drug on the replication of DNA, cultures of murine fibroblasts were synchronized by thymidine double block, and BD-40 was added at the time of the block release. The drug did not interfere with the entry of cells in S phase, but a delay in S-phase transit was observed, regardless of the dose employed. In agreement with these data, DNA synthesis started at the same time in control cells and in BD-40 treated cells, but a significant reduction of 3H thymidine incorporation was found in drug-treated cells. This inhibition was not likely to result from a diminution of the specific activity of 3H-dTTP, since nuclei, isolated from cells previously incubated with the drug, also presented a strong diminution of synthetic activity in the presence of the four nucleoside triphosphate precursors (dNTPs). Analysis by alkaline sucrose gradient centrifugation of DNA synthesized in the presence of BD-40 showed that primary fragments, probably corresponding to the duplication of initial replicons, were normally formed but were not further elongated in cells treated with cytotoxic doses, while they were normally processed (although at a slower rate than in control) with a cytostatic drug concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2003

DNA adduct formation by the anticancer drug ellipticine in rats determined by 32P postlabeling.

Ellipticine is a potent antineoplastic agent whose mode of action is considered to be based mainly on DNA intercalation and/or inhibition of topoisomerase II. Recently, we found that ellipticine also forms covalent DNA adducts in vitro and that the formation of the major adduct is dependent on the activation of ellipticine by cytochrome P450 (CYP). Here, we investigated the capacity of ellipticine to form DNA adducts in vivo. Male Wistar rats were treated with ellipticine, and DNA from various organs was analyzed by (32)P postlabeling. Ellipticine-specific DNA adduct patterns, similar to those found in vitro, were detected in most test organs. Only DNA of testes was free of the ellipticine-DNA adducts. The highest level of DNA adducts was found in liver (19.7 adducts per 10(7) nucleotides), followed by spleen, lung, kidney, heart and brain. One major and one minor ellipticine-DNA adducts were found in DNA of all these organs of rats exposed to ellipticine. Besides these, 2 or 3 additional adducts were detected in DNA of liver, kidney, lung and heart. The predominant adduct formed in rat tissues in vivo was identical to the deoxyguanosine adduct generated in DNA by ellipticine in vitro as shown by cochromatography in 2 independent systems. Correlation studies showed that the formation of this major DNA adduct in vivo is mediated by CYP3A1- and CYP1A-dependent reactions. The results presented here are the first report showing the formation of CYP-mediated covalent DNA adducts by ellipticine in vivo and confirm the formation of covalent DNA adducts as a new mode of ellipticine action.

Animals↗
PubMed1986

The in vitro involvement of topoisomerase II in the activity of aza-ellipticine analogues is not correlated with drug activity on isolated nuclei.

Aza-ellipticines are DNA intercalative ellipticine analogues with antitumor activity that induce protein-linked DNA breaks in NIH 3T3 cells in culture. The effects of two aza-ellipticine congeners (BD-40 and BR-76) on the activity of purified Calf Thymus type II topoisomerase were studied using pUC13 DNA as substrate. DNA cleavage was stimulated by both molecules at those doses required for inducing lethal effects in cells (DE5O). This effect was reversed by high salt treatment, indicating that it was actually mediated by Topo II. Mapping of cleavage sites on linearized and 3' end-labelled pUC13 DNA showed that ellipticine and aza-ellipticines stimulated the same sites, which differed from those stimulated by m-AMSA. Decatenating activity of Topo II on Trypanosoma cruzi kDNA was both inhibited by ellipticine and BD-40 at concentrations much higher than DE50 concentrations. Activity of aza-ellipticines was also investigated on isolated nuclei. Unlike ellipticine which promoted DNA-breaking activity, BD-40 and BR-76 were repeatedly inactive. Prior treatment of DNA by Proteinase K did not reveal hidden breaks which are formed in intact cells treated with BD-40 (Vilarem et al., 1984, Nucleic Ac. Res. 12, 8653). Concordant with these data, BD-40 did not impair DNA-synthetic activity in isolated nuclei, while Ellipticine largely decreased it. These results indicate that lesions induced in DNA by Aza-ellipticines are mediated by Topo II. The absence of effect of these drugs on isolated nuclei compared to that of Ellipticine may be due to some specific features of the association between Topo II and Aza-ellipticines or reflect a bioactivation step as a prerequisite for in vivo activity.

Alkaloids↗
PubMed1987

In vivo exposure to four ellipticine derivatives with topoisomerase inhibitory activity results in chromosome clumping and sister chromatid exchange in murine bone marrow cells.

A single dose of 9-hydroxy-ellipticine, 2-N-methyl-9-hydroxy-ellipticine, 9-fluoro-ellipticine, and 9-amino-ellipticine (5 to 10 mg/kg body wt, ip) resulted in murine bone marrow toxicity as shown by chromosome clumping, chromatid aberrations, and micronuclei formation. An increase in sister chromatid exchanges (SCE) was also observed. These effects are most likely directly related to the topoisomerase inhibitory effect of these drugs since topoisomerase II is involved in the separation of intertwined chromosomal DNA molecules during mitosis as well as being a mediator of DNA exchanges. The two antitumor drugs 2-N-methyl-9-hydroxy-ellipticine and 9-hydroxy-ellipticine were most genotoxic with chromosome abnormalities occurring in 33-95% of the cells and SCE on the order of 12.3 to 19.2 events per cell. Both of these drugs show high topoisomerase II inhibitory activity in vitro. In contrast, 9-amino-ellipticine and 9-fluoro-ellipticine were less genotoxic with chromosomal abnormalities occurring in 14-17% of the cells and SCE on the order of 7.1 to 7.7 events per cell. These two derivatives are both inactive toward experimental tumors and show less topoisomerase II inhibitory activity in vitro. Our results suggest that the ellipticine drugs owe at least some of their cytotoxicity to their genotoxic effects, which seem to be mediated through interaction with topoisomerase II.

Alkaloids↗
PubMed2002

Covalent binding of the anticancer drug ellipticine to DNA in V79 cells transfected with human cytochrome P450 enzymes.

Ellipticine is a potent antineoplastic agent whose mechanism of action is considered to be based mainly on DNA intercalation and/or inhibition of topoisomerase II. Recently, we found that ellipticine also forms covalent DNA adducts and that the formation of the major adduct is dependent on the activation of ellipticine by cytochrome P450 (CYP). We examined a panel of genetically engineered V79 cell lines including the parental line V79MZ and recombinant cells expressing the human CYP enzymes CYP1A1, CYP1A2 or CYP3A4 for their ability to activate ellipticine. The extent of activation was determined by analysing DNA adducts by 32P-postlabelling. Ellipticine was found to be toxic to all V79 cell lines with IC(50) values ranging from 0.25 to 0.40 microM. The nuclease P1 version of the 32P-postlabelling assay yielded a similar pattern of ellipticine-DNA adducts with two major adducts in all cells, the formation of only one of which was dependent on CYP activity. This pattern is identical to that detected in DNA reacted with ellipticine and the reconstituted CYP enzyme system in vitro as confirmed by HPLC of the isolated adducts. Total adduct levels ranged from 2 to 337 adducts per 10(8) nucleotides, in the parental line and in V79 expressing CYP3A4, respectively. As in vitro, human CYP1A2 and CYP1A1 were less active. The results presented here are the first report showing the formation of CYP-mediated covalent DNA adducts by ellipticine in cells in culture, and confirm the formation of covalent DNA adducts as a new mechanism of ellipticine action.

Animals↗
PubMedDate not supplied

Comparative physiological disposition of ellipticine in several animal species after intravenous administration.

The physiological dispositon of ellipticine (NSC 71795) has been studied in the mouse, rat, dog and monkey after administration of [1-14C]ellipticine at 6 mg/kg iv (3 mg/kg to monkey). Ellipticine was very rapidly distributed from the blood of all species and was deposited in tissues. The rate of elimination of ellipticine from blood was species-dependent, half-times ranging from 22 min in mouse to 210 min in rat, and probably reflected the rate of metabolism of the drug. The rate of elimination of metabolites from blood was also species-dependent, half-times ranging from 140 min in mouse to 380 min in rat, and probably reflected the rate of biliary secretion of the metabolites. Ellipticine was widely but not uniformly distributed throughout the tissues including brain, and some of the highest concentrations of drug and metabolites were in liver, which is probably the primary site of metabolism. The concentrations of ellipticine and metabolites in tissues were species-dependent, correlating with species differences in rates of metabolism and excretion. All species excreted 80% of the dose via the fecal route and 10% via the urinary route, primarily as metabolites during the first 24 hr after dosing. Metabolites entered the gastrointestinal tract by biliary secretion and ellipticine entered by an ion-trapping mechanism. Evidence is presented that the major pathway for ellipticine metabolism in rat was to 9-hydroxyellipticine, which did not accumulate in liver but was conjugated to its glucuronide and sulfate, which were secreted in bile. Other pathways involved hydroxylation and glucuronide conjugation. The pharmacokinetics of ellipticine are correlated with its toxic side effects, such as acute hypotention and neurological symptoms. They are also correlated with its potential as an antitumor agent, such as its ability to achieve values for the area under the curve of concentration vs. time (CXt) in tumors, which would be adequate for therapy. Based upon these correlations, the drug should be administered in the clinic by iv infusion, or, provided its bioavailability is found to be satisfactory, by the oral route.

Alkaloids↗
PubMed1978

Dissolution and absorption of the antineoplastic agent ellipticine.

Ellipticine, a poorly water-soluble alkaloid, is active in several experimental tumor systems. Marked solubility increases were produced by polyvinylpyrrolidone of varying molecular weights (10,000--160,000) and were optimal (approximately 13 mg/ml at 25 degrees) with polyvinylpyrrolidone mol. wt 10,000. Dissolution of ellipticine--polyvinylpyrrlidone (1:22 w/w) tablets in simulated gastric juice was superior to that of ellipticine hydrochloride polymers without affecting maximum dissolution at 37 degrees. Physiological disposition of ellipticine--polyvinylpyrrolidone was compared with that of the hydrochloride salt and ellipticine in suspension following oral administration at 250 mg/kg in fasted mice. In comparison to the suspension, ellipticine tissue levels were about threefold higher with polyvinylpyrrolidone or hydrochloride preparations. Antitumor activity of the three preparations was evaluated intraperitonneally and orally versus L-1210 leukemia. The optimal dose of ellipticine--polyvinylpyrrolidone and ellipticine hydrochloride was lower than that of the suspension and suggested improved absorption.

Administration, Oral↗
PubMed1989

Topoisomerase II-mediated DNA cleavage activity induced by ellipticines on the human tumor cell line N417.

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.

Alkaloids↗
PubMed1992

Ellipticine increases the superhelical density of intracellular SV40 DNA by intercalation.

We investigated the in vivo effect of ellipticine, a mammalian topoisomeraseII(topoII) inhibitor, on SV40 DNA topology. In contrast to epipodophyllotoxins, ellipticine did not cause significant double stranded cleavage of intracellular SV40 DNA. Furthermore, ellipticine reduced cleavage induced by epipodophyllotoxins, VP16 and VM26. Unexpectedly, ellipticine dramatically increased the superhelical density of a fraction of intracellular SV40 DNA. Several lines of evidence suggest that the formation of this highly supercoiled DNA species (Ih form DNA) is not due to the inhibition of topoII per se, but is the result of intercalation by ellipticine in a subfraction of the intracellular SV40 chromatin followed by the fixation of DNA linking number by a topoisomerase activity. Based on the linking number change and the known unwinding angle of ellipticine, the intercalation density was calculated as one ellipticine molecule per 10-20 bp in the Ih DNA. This result suggests the existence of different populations of intracellular SV40 chromatin with respect to the accessibility to ellipticine intercalation.

Cell Line↗
PubMed1985

Differential effects of ellipticine and aza-analogue derivatives on cell cycle progression and survival of BALB/c 3T3 cells released from serum starvation or thymidine double block.

10-[Diethylaminopropylamino]-6-methyl-5H-pyrido[3',4':4,5] pyrrolo[2,3-g]isoquinoline (BD-40) (NSC-327471D) is an aza-ellipticine derivative with a promising antitumor activity (M. Marty, C. Jasmin, P. Pouillard, C. Gisselbrecht, G. Gouvenia, and H. Magdalainat, 17th Annual Meeting of the American Society of Clinical Oncology, C-108, 1981) and less toxicity than ellipticine. We have compared the effects of ellipticine, several of its analogues, and two aza-analogue ellipticine derivatives (BD-40 and BR-1376) on cell cycle progression of BALB/c 3T3 mouse cells under different growth conditions. Both drug series were found to stop cell growth and block cells in G2 phase in exponentially growing cultures and cultures released from a thymidine double block. Long-term viability of these cells was completely suppressed after a short exposure to the drugs. In contrast, while ellipticine and its derivatives caused identical effects in cells recovering from serum starvation, BD-40 and BR-1376 did not block cells in G2 phase and did not prevent the completion of the first division round occurring after serum addition to quiescent cells. This transient refractory state was accompanied by a total conservation of long-term viability of these cells at least for the next 6 h following serum and drug addition. This lack of effect was not related to an impaired drug uptake by cells recovering from serum starvation or by a dramatic change in drug distribution inside the cells. These results indicate that the nitrogen substitution in the ellipticine heterocycle is an important if not unique feature for the particular effect of the aza-analogues of ellipticine. Furthermore, they suggest that, in contrast to ellipticine derivatives, these compounds require an activation step before exhibiting cytotoxicity.

Alkaloids↗
PubMed1987

Mutagenesis of L5178Y/TK(+/-)-3.7.2C mouse lymphoma cells by the clastogen ellipticine.

Ellipticine is a potent clastogen in CHO cells (Bhuyan et al: Cancer Res 32:2538-2544, 1972). The reported mutant frequencies produced by ellipticine at the hprt locus in CHO cells are less than or equal to 50/10(6) survivors (background approximately 2/10(6); survival = 10%) (DeMarini et al: Cancer Res 43:3544-3552, 1983; Singh and Gupta: Cancer Res 43:577-584, 1983; Environ Mutagen 5:871-880, 1983). In the present study, the mutagenic and clastogenic activities of ellipticine were evaluated in L5178Y/TK(+/-)-3.7.2C mouse lymphoma cells. Unlike the results at the hprt locus, ellipticine is a potent mutagen at the tk locus, with as little as 50 ng/ml producing an induced mutant frequency of 142/10(6) survivors (background = 56/10(6); survival = 61%) and 198/10(6) survivors (background = 72/10(6); survival = 50%) in two separate experiments. This same dose of ellipticine induced 44 aberrations per 100 metaphases (background = 5/100 cells). At 400 ng/ml, ellipticine induced over 1,000 mutants/10(6) survivors at approximately 10% survival and produced 242 aberrations/100 cells. Under the test conditions, most of the aberrations were chromosome rather than chromatid events. As expected for a compound acting primarily by a clastogenic mechanism, almost all of the TK-deficient mutants were small colonies. Thus, ellipticine is a potent clastogen in both Chinese hamster cells and in mouse lymphoma cells; however, it is a potent mutagen at only the tk locus and not at the hprt locus. These results support the hypothesis that the location of the target gene affects the ability of the assay to detect both intragenic events and events causing the loss of multiple loci. Thus, a heterozygous locus (like tk) but not a functionally hemizygous locus (like hprt) may permit the more efficient detection of mutagens that act primarily by a clastogenic mechanism.

Alkaloids↗
PubMed1990

9-amino-ellipticine inhibits the apurinic site-dependent base excision-repair pathway.

The aromatic amine 9-amino-ellipticine is a synthetic DNA intercalating compound derived from the antitumor agent ellipticine, which cleaves at very low doses DNA containing apurinic sites by beta-elimination through formation of a Schiff base. This compound has been shown to potentiate the cytotoxic effect of alkylating drugs, such as dimethyl sulfate, in E. coli through a mechanism involving apurinic sites. We have studied the ability of 9-amino-ellipticine to inhibit an enzymatic repair system mimicking base-excision repair, in which E. coli exonuclease III only presents an endonuclease for apurinic/apyrimidinic site activity. 10 microM of 9-amino-ellipticine inhibits 70% of apurinic site repair. Other intercalating agents with similar affinities for DNA do not induce any inhibition. In another system designed for the direct assay of the exonuclease III-induced incisions 5' to AP sites 10 microM of 9-amino-ellipticine inhibits 65% of the endonuclease for apurinic/apyrimidinic site activity of E. coli exonuclease III. The 9-amino-ellipticine-induced formation of a 2',3'-unsaturated deoxyribose and cleavage at the 3' side of the apurinic site, and possible creation of an adduct, as suggested by Bertrand and coworkers (1989), on the 3' position of the deoxyribose seem to strongly inhibit the endonuclease for apurinic/apyrimidinic site activity. 9-Amino-ellipticine appears therefore to be the first small ligand which can inhibit, by an irreversible modification of the substrate, the repair of apurinic sites through the base excision-repair pathway at a pharmacological concentration.

Alkaloids↗