Biomedical subjects

G Atassi

Publications and source records attributed to G Atassi.

At least 73 records · Page 4Linked to original sources

PubMed1996

Synthesis and anti-proliferative activity of 2-hydroxy-1,2-dihydroacronycine glycosides.

PURPOSE: Combination of the acronycine pharmacophore with various sugar units appeared of interest, since numerous anticancer agents possess a sugar moiety, which strongly influence both their bioavailability and their selective toxicity towards tumor cells. METHODS: A series of 2-hydroxy-1,2-dihydroacronycine glycosides were synthetized, by condensation of the racemic aglycone with appropriate glycoside donors. Their effect on the inhibition of L1210 cell proliferation were evaluated. RESULTS: Compounds 6a, 6b, 11a, 11b, and 12a, 12b, including a halogenated sugar moiety displayed activities of the same order of magnitude as acronycine itself. Compounds 7a, 7b, and 8a, 8b, bearing a 2.3.6-trideoxy-3-azido-L-lyxo- and L-arabino-hexopyranose unit respectively, were significantly more potent than acronycine in inhibiting cell proliferation. CONCLUSIONS: The activity of 2-hydroxy-1,2-dihydroacronycine glycosides seems to be related to the lipophilicity of the sugar unit.

Acronine↗

PubMed1996

Synthesis and cytotoxic activity of acronycine derivatives modified at the pyran ring.

Nitration of acronycine (1) and 6-demethoxyacronycine (3) afforded 2-nitroacronycine (2) and 2-nitro-6-demethoxyacronycine (4), respectively. Reduction of 2-nitroacronycine yielded, depending on the conditions, 2-nitro-1,2-dihydroacronycine (5), 2-oxo-1,2-dihydroacronycine oxime (7) or 2-amino-1,2-dihydroacronycine (6). This latter was readily converted into 2-dimethylamino-1,2-dihydroacronycine (8), 2-acetylamino-1,2-dihydro-acronycine (9) and 2-benzoylamino-1,2-dihydroacronycine (10). The cytotoxicity of these compounds was evaluated against L1210 leukemia cells. Compounds 2 and 7 were 300- and 10-fold more potent than acronycine in inhibiting L1210 cell proliferation, respectively. Compound 2 was devoid of antitumor activity against P388 leukemia and C38 colon adenocarcinoma.

Acronine↗

PubMed1996

Synthesis and biological evaluation of 6-(9-hydroxy-5-methyl (and 5,6-dimethyl)-6H-pyrido[4,3-b]carbazol-1-yl)picolinic amides as new olivacine derivatives.

Starting from 2-(6-methoxy-1-methylcarbazol-2-yl)ethylamine and diethyl-2,6-pyridine dicarboxylate, the title compounds were obtained through five or six steps. The new compounds retained significant cytotoxicity towards various tumor cell lines, but in vivo studies on murine P388 leukemia, B16 melanoma and Lewis lung carcinoma showed a lowered antitumor activity with respect to that of the related olivacine lead compound 1.

Animals↗

PubMed1995

Combination of computerized morphonuclear and multivariate analyses to characterize in vitro the antineoplastic effect of alkylating agents.

The influence of 13 anticancer alkylating agents on cell proliferation, cell cycle parameters, and morphonuclear characteristics was monitored in vitro on three neoplastic cell lines. This monitoring was carried out by means of the digital cell image analysis of Feulgen-stained nuclei. This computer-assisted microscope analysis of chromatin texture made it possible to assess 15 morphonuclear parameters. These 15 parameters were submitted to multivariate analyses, that is, principal-components analyses followed by the canonical transformation of the data. The 13 alkylating agents included four nitrogen mustards (chlormethine, chlorambucil, melphalan, and cyclophosphamide), two nitrosoureas (carmustine and lomustine), two platinum analogues (cisplatine and carboplatine), two ethyleneimine derivatives (thiotepa and investigational PE1001), one antibiotic (mitomycin C), one alkylsulfonate (busulfan), and one triazene (dacarbazine). The mouse MXT mammary and the human J82 and T24 bladder tumor cell lines were used in this study. The results show that these alkylating agents induced specific modifications to the chromatin pattern according to the subclass to which they belong. In other words, the multivariate statistical analyses of the 15 parameters made it possible to identify, at least partly, distinct subclasses of alkylating agents according to their mechanisms of action. As a validation of the methodology, the results also show that most of the alkylating agents induced an increase in the percentage of cells in the G2 phase, while some sometimes induced an increase in the percentage of cells in the S phase of the cell cycle.

Adenocarcinoma↗

PubMed1995

Characterization of alkylating versus intercalating anticancer drug-induced effects on cell survival, cell cycle kinetic and morphonuclear pattern of three neoplastic cells lines growing in vitro.

PURPOSE: The influence of three alkylating and three intercalating anticancer drugs on cell survival, cell cycle kinetics and chromatin patterns was monitored in vitro on three neoplastic cell lines. METHODS: This monitoring was carried out by means of the digital cell image analysis of Feulgen-stained nuclei. RESULTS: Results show that in term of cytotoxicity, the intercalating drugs were more potent than the alkylating ones. As for the cell kinetics assessment, most of the experimental conditions led to a blockage of the cells in the G2 phase of the cell cycle. A study of chromatin patterns by means of digital cell image analysis enabled us to describe 15 morphonuclear parameters. The results show that the drugs tested induced specific morphonuclear modifications, e.g. an increase in nuclear size. The 15 morphonuclear parameters were submitted to multivariate analyses, i.e. principal-components analyses followed by the canonical transformation of the data. The results of these multivariate analyses enabled us to discriminate between the alkylating and the intercalating drugs. CONCLUSIONS: We conclude that it would be possible to "diagnose" the mechanism of action of DNA interacting agents (alkylating or intercalating drugs) by means of the combination of digital cell image and multivariate analysis.

Adenocarcinoma↗

PubMed1995

Cytotoxicity, cell cycle kinetics and morphonuclear-induced effects of Vinca alkaloid anticancer agents.

The effects of four Vinca alkaloids (vinblastine, vincristine, vindesine and vinorelbine) on three neoplastic cell lines (the MXT mouse mammary cell line and the T24 and J82 bladder cell lines) were studied at three biological levels, i.e. cell proliferation, cell cycle kinetics and morphonuclear characteristics. These effects were studied by means of digital cell image analysis on Feulgen-stained nuclei. The aim of the present work was to characterize the effects specifically induced by Vinca alkaloids as compared with those obtained previously with other pharmacological classes of anticancer drugs. The results show that Vinca alkaloids inhibit the cell proliferation of neoplastic cell lines at a concentration of 10(-8) M except in the case of the J82 cell line, for which only a slowing down of cell proliferation was observed. Concerning the cell cycle kinetics, the results show that the Vinca alkaloids induce an accumulation of cells in the mitosis phase. This accumulation of mitotic cells was maximal after 15 h incubation in the presence of the drugs. A study of the morphonuclear-induced effects of Vinca alkaloids showed that the variance of the optical density (VOD) is strongly influenced by these Vinca alkaloids. The development of the VOD was parallel with the development of the percentage of mitosis; thus, the VOD enabled the Vinca alkaloid-induced effects to be specifically characterized from a morphonuclear point of view. On the other hand, the results show that the mean value of the variance of the optical density was very highly correlated (P < 0.001) with the efficiency of the Vinca alkaloids in terms of cytotoxicity. In clinical studies, the analysis of the development of this parameter would make it possible to assess the response to chemotherapy in the case of patients treated with Vinca alkaloids.

Adenocarcinoma↗

PubMed1995

Flow cytometric evaluation of multidrug-resistance circumvention.

Flow cytometry, through the measurement of P-gp expression and function, is an important tool in the characterization of multidrug resistant cell lines used in pharmacology. Furthermore, as a complement to classical in vitro tests, this technique allows rapid evaluation of the capacity of new modulator agents to reverse the resistance to cytotoxic drugs and contributes a deeper insight into the mechanism of action of these new molecules.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1995

In vitro digital cell image analysis of morphonuclear modifications induced by natural DNA-interacting anticancer drugs in three neoplastic cell lines.

The effects of seven natural anticancer drugs acting through interaction with DNA were characterized at three levels: cell proliferation, cell cycle kinetics and chromatin texture. These drug-induced effects were monitored in vitro by means of the digital cell image analysis which provides 15 morphonuclear parameters. In terms of cell proliferation, results show that the drug-induced effects ranged from 10(-11)M to 10(-6)M. With respect to the cell cycle kinetics, the results show that the drugs induced an accumulation of the cells in the G2 phase. Concerning the chromatin levels, the results show that it is possible to classify the drugs according to their mechanism of action on the basis of the multivariate analysis of the 15 parameters.

Animals↗

PubMed1994

Synthesis and evaluation of 9-hydroxy-5-methyl-(and 5,6-dimethyl)-6H-pyrido[4,3-b]carbazole-1-N- [(dialkylamino)alkyl]carboxamides, a new promising series of antitumor olivacine derivatives.

Starting from 2-(2-aminoethyl)-6-methoxy-1-methylcarbazole, ethyl 9-methoxy-5-methyl-6H-pyrido[4,3-b]carbazole-1-carboxylate was obtained through a three-step sequence. This compound and its 6-methyl derivative react with (dialkylamino)alkylamines to provide various 9-methoxy-5-methyl-6H-pyrido[4,3-b]carbazole-1-(N-substituted carboxamides) whose boron tribromide demethylation afforded corresponding 9-hydroxy-1-(N-substituted carbamoyl)-olivacines. The same pathway but starting from 2-(2-aminoethyl)-6-methoxy-1,4-dimethylcarbazole led to ethyl 9-methoxy-5,11-dimethyl-6H-pyrido[4,3-b]carbazole-1-carboxylate which did not normally react with amines. It provided either the recovered starting material at 120 degrees C or 9-methoxyellipticine resulting from an unexpected decarboethylation in a steel vessel at 180 degrees C. Biological testing of the newly obtained 1-carbamoylolivacine derivatives showed that 9-hydroxylated compounds displayed high cytotoxicity for cultured L1210 and colon 38 cells (IC50 range 5-10 nM) and good antitumor activity in vivo in the P388 leukemia and colon 38 models when administered by the iv route. The most active compound in these series is 9-hydroxy-5,6-dimethyl-1-[N-[2-(dimethylamino)ethyl]carbamoyl]-6H- pyrido[4,3-b]carbazole which was selected for further evaluation on murine solid tumors and for toxicological studies.

Adenocarcinoma↗

PubMed1994

Computer-assisted microscope analysis of morphonuclear modifications induced by anticancer antimetabolites in cell lines cultured in vitro.

An original method is proposed for the purpose of discriminating between antimetabolites exhibiting different operating mechanisms. The present work was carried out by means of the digital cell image analysis of Feulgen-stained nuclei cultured in the presence of different antimetabolites. We chose this method because it enables anticancer drug-induced effects to be studied at both morphonuclear and cell cycle levels in the same biological sample. The results show that all the antimetabolites had similar effects on the nuclear texture of the cells and on cell cycle parameters. Furthermore, the use of multivariate analyses made it possible to distinguish between different mechanisms of action among drugs belonging to the same class of antineoplastic, i.e. antimetabolite agents.

Animals↗

PubMed1994

In vivo reversal of multidrug resistance by two new dihydropyridine derivatives, S16317 and S16324.

Two new dihydropyridine derivatives with low calcium channel affinity, S16317 and S16324, were found to fully overcome multidrug resistance in vitro. These two compounds increased doxorubicin cytotoxicity on the human COLO 320DM cell line and completely reversed the vincristine resistance of murine P388/VCR cells. In vivo, S16324 administered p.o. (200 mg/kg on days 1 to 4) or i.p. (50 mg/kg on days 1, 5, 9) in combination with vincristine (i.p.) restored the antitumor activity of vincristine in P388/VCR-bearing mice. S16317 showed a reversing activity when administered p.o., i.v. (days 1 to 4) or i.p. (days 1, 5, 9) at the same dose (25 mg/kg), suggesting a remarkable bioavailability. Moreover, these two compounds potentiated the antitumor activity of vincristine in the sensitive P388 leukemia, increasing the number of long-term survivors. These results suggest that combination chemotherapy using S16317 or S16324 would be effective not only in circumventing multidrug resistance but also in preventing the emergency of a population of resistant tumor cells in sensitive tumors.

Adenocarcinoma↗

PubMed1994

Synthesis and biological activity of 3'-deamino-3'-haloanthracyclines.

4'-O-Acetyl-3'-deamino-3'-chloro and 4'-O-acetyl-3'-deamino-3'-bromoepidaunorubicin analogs have been synthesized by condensation of daunomycinone with the corresponding hexopyranosyl chlorides. The glycosides obtained were less potent than adriamycin (ADR) in inhibiting the proliferation of tumor cells in vitro, but they have shown promising activity against a variety of multidrug resistant (MDR) cell lines.

Animals↗

PubMed1993

[In vitro characterization of S9788, a new modulator of multidrug resistance].

S9788, a new triazinoaminopiperidine derivative, was 250-fold more active than verapamil in sensitizing DC-3F/AD cells to actinomycin D. This multidrug-resistance modulating activity of S9788 was confirmed on DC-3F/AD, P388/ADR-10, P388/VCR-20, KB/A1, K562/R, S1/tMDR, and COLO320DM cells, with respect to actinomycin D, doxorubicin, vincristine, vinblastine and etoposide. S9788 is 2-255-fold more active than verapamil, depending on the cell line and the cytotoxic agent used, potentiating preferentially the cytotoxicity of the vinca-alkaloid derivatives. S9788 only had a slight effect on vincristine accumulation and retention by parental sensitive cells, as well as on their sensitivity to cytotoxic drugs. S9788 fully restored vincristine accumulation and retention by S1/tMDR cells (S1 cells transfected by the mdr 1 gene) to a level similar to that measured in S1 cells, leading to a blockade in the G2 + M phase of the cell cycle. Therefore, S9788 enhances vincristine activity by restoring its cellular accumulation in resistant cells. After a short incubation period of cells with vincristine (4 h), a condition close to the clinical administration of this cytotoxic agent, a post-incubation for 20 hours more with 5 microM S9788, fully restored the sensitivity of S1/tMDR cells to vincristine. After an exposure of 4 hours at equal concentrations, the accumulation of S9788 was 13-fold that of verapamil in S1/tMDR cells, and 20 hours after the removal of the modulators, S9788 was retained at a concentration 20-fold that of verapamil. S9788 is therefore a powerful new modifier of the P-gp-mediated multidrug-resistance, which by its pharmacological properties (cellular kinetics and activity), might be used in combination with existing chemotherapy against tumors displaying the MDR phenotype.

Animals↗

PubMed1993

Synthesis and evaluation of 4-amino-substituted 7-methoxy (and 7-hydroxy)- 11-methyl (and 5,11-dimethyl)-10H-pyrido [2,3-b] carbazoles and 4-amino- substituted 11-methyl (and 5,11-dimethyl)-10H-pyrido[3',4':4,5] pyrrolo [3,2-g] quinolines, two new series related to antitumor ellipticine derivatives.

2-Acetyl-4-chloro-3-lithiopyridine ethylene glycol ketal (6b) was reacted with 3-formyl-5-methoxy-1-methyl-indole (9) and 3-formyl-1-methyl-1H-pyrrolo [3,2-c] pyridine (12), giving the corresponding expected alcohols. Reduction of these intermediates with triethylsilane trifluoroacetic acid and subsequent cyclodehydration then led to 4-chloro-7-methoxy-10,11-dimethyl-10H-pyrido [2,3-b] carbazole (8a) and the corresponding 7-aza-analog (8b). The synthesis of 4-chloro-11-methyl (and 5,11-dimethyl)-10-unsubstituted derivatives of these two series was performed through an independent pathway, involving condensation of conveniently substituted 2-amino carbazoles (17) and 7-amino-5H-pyrido [4,3-b] indoles (18) with 5-(ethoxymethylene)-2,2-dimethyl-1,3-dioxane-4,6-dione, thermal cyclization of the resulting compounds with concomitant decarboxylation to the corresponding tetracyclic fused-4-quinolone systems and final chlorination with phosphorus oxychloride. Nucleophilic substitution of various 4-chloro derivatives was then easily performed in an excess of the required dialkylamino alkylamines at reflux and 4-amino substituted-7-hydroxy-10H- pyrido [2,3-b] carbazoles (25d-e) were obtained from 7-methoxy precursors (25a-b), by demethylation with boron tribromide in methylene chloride at -65 degrees C or with boiling 47% hydrobromic acid. Cytotoxicity determination of all new aminosubstituted derivatives and in vivo antitumor evaluation of the most active compounds clearly show that these two series of ellipticine analogs closely related to highly active products are devoid of antitumor properties in two experimental models shown to be sensitive to ellipticines. The place of the pyridinic nitrogen atom in these series has thus been demonstrated to play a crucial role in antitumor activity.

Animals↗

PubMed1992

Effects of a new triazinoaminopiperidine derivative on adriamycin accumulation and retention in cells displaying P-glycoprotein-mediated multidrug resistance.

A new triazinoaminopiperidine derivative, Servier 9788 (S9788), was investigated for its ability to increase Adriamycin (ADR) accumulation and retention in two rodent (P388/ADR and DC-3F/AD) and three human (KB-A1, K562/R and COLO 320DM) cell lines displaying the P-glycoprotein (P-gp)-mediated multidrug resistance (MDR) phenotype. Depending on the cell line S9788 was shown to be two to five times more active and five to 15 times more potent than Verapamil (VRP) in increasing ADR accumulation in resistant cells. ADR retention in KB-A1 cells maintained in a concentration of 10 microM S9788 was twice that in VRP-treated cells, and similar to that measured in the untreated sensitive KB-3-1 cells. Although 5 microM S9788 and 50 microM VRP gave the same values of ADR uptake in KB-A1 cells, S9788 was shown to induce a greater ADR retention following cell wash and post-incubation in resistance modifier- and ADR-free medium. Taking into account that S9788 had no effects on ADR accumulation and retention in sensitive KB-3-1 cells, it can be suggested that S9788 inhibits specifically the P-gp dependent ADR efflux, and in a manner less reversible than that observed with VRP. Moreover, [3H]azidopine photolabeling of P-gp, in P388/ADR plasma membranes, was completely inhibited by 100 microM S9788. Although S9788, as VRP, had no effect on the cell cycle of P388 cells, 5 microM S9788 increased 700-fold the efficacy of ADR to block P388/ADR cells in the G2+M phase of the cell cycle. Together, these results show that the sensitization, by S9788, of cell lines resistant to ADR is mainly due to an increase in ADR accumulation and retention, leading to an increase in the number of resistant cells blocked in the G2+M phase.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1992

New triazine derivatives as potent modulators of multidrug resistance.

A series of 70 triazine derivatives have been synthesized and tested for their capacity to modulate multidrug resistance (MDR) in DC-3F/AD and KB-A1 tumor cells in vitro, in comparison with verapamil (VRP), a calcium channel antagonist currently used in therapy as an antihypertensive drug, which also shows MDR modulating activity. Among the 12 selected compounds, 16 (S9788) showed high MDR reversing properties in vitro (300- and 6-fold VRP at 5 microM in DC-3F/AD and KB-A1 cells, respectively) and induced a strong accumulation of adriamycin. The relationship between the increase of ADR accumulation and the fold reversal induced by these compounds and their lack of effects on the sensitive DC-3F cells suggest that they act mainly by inhibiting the P-glycoprotein (Pgp) catalyzed efflux of cytotoxic agents, as already described for a majority of MDR modulators. In vivo, in association with the antitumor drug vincristine (0.25 mg/kg), 16 (100 mg/kg) increased the T/C by 39% in mice bearing the resistant tumor cell line P388/VCR. According to these interesting properties, 16 was selected for a clinical development because it was more bioavailable than 34, even though it was less active.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1992

In vivo evidence of complete circumvention of vincristine resistance by a new triazinoaminopiperidine derivative S 9788 in P388/VCR leukemia model.

S 9788, a new triazinoaminopiperidine derivative, was found to be a potent reversant of vincristine resistance in the in vivo murine leukemic P388/VCR model. In two treatment regimens (Q4D days 1, 5 and 9 and QD days 1-9), S 9788 enhanced the antitumor activity of vincristine in a dose-dependent manner, resulting in a complete circumvention of drug resistance for well-tolerated doses of S 9788. S 9788 was also effective in enhancing therapeutic effects of vincristine in the treatment of sensitive P388-bearing mice. These results strongly suggest that S 9788 may be a potential candidate for circumvention of multidrug resistance (MDR) in clinical practice.

Animals↗

PubMed1992

Relationship between the cellular accumulation and the cytotoxicity of S12363, a new Vinca alkaloid derivative.

S12363, a new vinca alkaloid derivative, was considerably more cytotoxic to murine L1210 cells and five human tumor cell lines (HL60, HT-29, COLO 320DM, NCI-H460, and PANC-1) than was vincristine (VCR) or vinblastine (VLB). S 12,363 bound to tubulin in crude extracts from brain or L1210 cells with an affinity similar to that of VLB and VCR (apparent Kd value: 1.1-1.6, 1.2-1.7, and 0.6-0.8 microM, respectively). After 1 h exposure, the accumulation of 20 nM [3H]-S 12,363 by L1210 cells was 4- to 18-fold that of [3H]-VLB and [3H]-VCR, respectively. After the cells had been preloaded for 1 h with the labeled drugs and then incubated for 3 h in drug-free medium, 37%-55% of the [3H]-S 12,363 was retained by the cells vs 36%-47% of the [3H]-VCR and less than 6% of the [3H]-VLB. Similar results were obtained for the five human cell lines tested. The accumulation factors (intracellular vs extracellular concentrations) found for [3H]-S 12,363 (54- to 167-fold) were significantly higher than those observed for [3H]-VCR (5- to 14-fold) or [3H]-VLB (19- to 41-fold). Greater than 90% of the radioactivity extracted from L1210 cells that had been treated with [3H]-S 12,363 was recovered as unmodified drug, demonstrating that [3H]-S 12,363 was not metabolized by these cells. S 12,362, which differs from S 12,363 only in the absolute configuration of the asymmetric carbon atom of its alpha-aminophosphonic side chain, was 300 times less cytotoxic, bound to tubulin with a lower affinity (apparent Kd value, 4.9-9.6 microM), and was neither accumulated nor retained by the cells. Taken together, these results demonstrate that the potency of S 12,363 is due at least in part to its cellular accumulation and retention.

Animals↗