Induction of cyclin E and inhibition of DNA synthesis by the novel acronycine derivative S23906-1 precede the irreversible arrest of tumor cells in S phase leading to apoptosis.

S23906-1 is a diester derivative of 1,2-dihydrobenzo[b]acronycine with an unknown mechanism of action. This cytotoxic compound was 20-fold more potent than acronycine in inhibiting the proliferation of six tumor cell lines. Using a clonogenic assay of cell survival, the HT29 human colon carcinoma cell line was 100-fold more sensitive to S23906-1 than acronycine. Cell cycle analysis, by flow cytometry, showed that S23906-1 induced a partially reversible arrest of HT29 cells in G2+M at 1 microM and below and an irreversible arrest in S phase at 2.5 microM and above. These cell cycle effects were followed by cell death through apoptosis, quantified by annexin-V labeling. Inhibition of DNA synthesis was observed by complete prevention of bromodeoxyuridine (BrdU) incorporation after only 4 h of incubation with 5 microM S23906-1. Interestingly, under the same experimental conditions, a significant increase of cyclin E protein level was observed without any modification of cyclins D1, D2, D3, or A. This overexpressed cyclin E protein was not complexed with Cdk2, as shown by western blotting for Cdk2 in immunoprecipitates of cyclin E. Similar inhibition of BrdU incorporation and elevation of cyclin E protein were observed after treatment with cytosine arabinoside, which reversibly inhibited progression into S phase, but not after DNA damage induced by cisplatin. S23906-1 thus has a novel mechanism of action. A cell line resistant to S23906-1 showed that overexpression of cyclin E was implicated in the novel cytotoxic activity of this compound.

Synthesis, cytotoxic activity, NMR study and stereochemical effects of some new pyrano[3,2-b]thioxanthen-6-ones and pyrano[2,3-c]thioxanthen-7-ones.

Some new substituted pyrano[3,2-b]thioxanthen-6-ones and pyrano[2,3-c]thioxanthen-7-ones were prepared and their cytotoxic activity was evaluated using acronycine as the reference compound. The conformation of the molecules was also investigated in an effort to correlate this parameter with the biological activity.

Synthesis and cytotoxic activity of benzophenanthrolinone analogues of acronycine.

Condensation of either 2-bromobenzoic acid (4) or 2-chloro-3-nitrobenzoic acid (5) with suitable aminoquinolines 6-8 afforded phenylquinolylamines 9-13. Acid mediated cyclization gave the corresponding 12H-benzo[b][1,7]phenanthrolin-7-ones 14 and 15, and 12H-benzo[b][1,10]phenanthrolin-7-ones 16-18. Compounds 14, 16, and 17 were subsequently N-methylated to 6-demethoxyacronycine and acronycine analogues 19-21, whereas reduction of the aromatic nitro group of 18 gave the amino derivative 22. Unsubstituted 12H-benzo[b][1,10]phenanthrolin-7-ones 16, 17, 20, and 21 were devoid of significant cytotoxic activity, whereas 18 and 22, bearing a nitrogen substituent at position 11, were significantly active. Unsubstituted 12H-benzo[b][1,7]phenanthrolin-7-ones 14 and 19, which include a pyridine nitrogen in the same 4-position as the pyran oxygen of acronycine exhibited cytotoxic activities within the same range of magnitude as acronycine itself.

Marked antitumor activity of a new potent acronycine derivative in orthotopic models of human solid tumors.

S 23906-1 is a novel acronycine derivative selected on the basis of its potency in vitro. We investigated the antitumor activity of S 23906-1 against several murine transplantable tumors (C38 colon carcinoma, P388 leukemia, B16 melanoma, and Lewis lung carcinoma) and in orthotopic models of human lung (NCI-H460 and A549), ovarian (IGROV1 and NIH:OVCAR-3), and colorectal cancers (HCT116 and HT-29). Against established C38 colon carcinoma, S 23906-1 administered twice i.v. from 1.56-6.25 mg/kg markedly inhibited tumor growth. Treatment at the optimal dose (6.25 mg/kg) induced tumor regression in all of the mice. Acronycine was 16-fold less potent and only moderately active at the maximum tolerated dose, 100 mg/kg. Against other murine tumors of the former National Cancer Institute panel, S 23906-1 was either only moderately active or totally inactive. When evaluated in human orthotopic models, S 23906-1 given p.o. or i.v. demonstrated a marked antitumor activity against human carcinomas. In the two human lung cancer models, S 23906-1 increased the survival of the animals in a dose-dependent manner and induced treated versus control values of 162% (NCI-H460) and 193% (A549). Vinorelbine was less active, with treated versus control values of 119% and 174%, respectively. A significant survival benefit was also observed against the two i.p. ovarian tumors in which S 23906-1 was as active as paclitaxel, inducing 80% long-term survivors in the NIH:OVCAR-3 model. Lastly, S 23906-1 inhibited the growth of primary HT-29 and HCT116 colon tumors grafted onto the cecum as efficiently as irinotecan and eradicated the formation of lymph node, hepatic, and pulmonary metastases in the aggressive HCT116 model. The novel spectrum of activity of S 23906-1 compared with existing anticancer agents warrants further preclinical investigation.

Design, synthesis and antiproliferative activity of tripentones: a new series of antitubulin agents.

Structure-activity relationship studies of a new series of tripentones (thieno[2,3-b]pyrrolizin-8-ones), led us to prepare several derivatives with antiproliferative activities. The most promising 3-(3-hydroxy-4-methoxyphenyl)thieno[2,3-b]pyrrolizin-8-one 20 (leukemia L1210, IC(50)=15 nM) was shown to be a potent inhibitor of tubulin polymerization.

Synthesis and cytotoxicity of artemisinin derivatives containing cyanoarylmethyl group.

A series of 12alpha-deoxoartemisinyl cyanoarylmethyl dicarboxylates (4a-4o), dicarboxylic acids 12alpha-deoxoartemisinyl ester cyanoarylmethyl amide (5a-5k), and dicarboxylic acids 12alpha-deoxoartemisinyl ester N-methylcyanoarylmethyl amide (6a-6l), showing moderate cytotoxicity against P388 and L1210 cells were prepared. They induced the significant accumulation of L1210 and P388 cells in the G1 phase of the cell cycle. This mechanism of action was quite different from that of the majority of cytotoxic compounds used in the chemotherapy of cancer. Compound 4b possessed better cytotoxicity than the other compounds.

A reappraisal of the potential chemopreventive and chemotherapeutic properties of resveratrol.

Resveratrol, a phytoalexin found in grapes and wines, has been reported to exhibit a wide range of pharmacological properties and is believed to play a role in the prevention of human cardiovascular disease (the so-called 'French paradox'). This molecule may also play a major role in both cancer prevention and therapy. In this review article we summarize the recent advances that have provided new insights into the molecular mechanisms underlying the promising properties of resveratrol. These include cyclooxygenase, nitric oxide synthase and cytochrome P450 inhibition, as well as cell cycle effects, apoptosis modulation and hormonal activity.

Synthesis and cytotoxic activity of benzopyranoxanthone analogues of benz.

Condensation of 3-hydroxy-2-naphthalenecarboxylic acid with phloroglucinol afforded 1,3-dihydroxy-12H-benzo[b]xanthen-12-one. Construction of an additional dimethylpyran ring onto this skeleton, by alkylation with 3-chloro-3-methyl-1-butyne followed by Claisen rearrangement, gave access to a series of benzo[b]pyrano[2,3-i]xanthen-6-ones and benzo[b]pyrano[3,2-h]xanthen-7-ones related to psorospermine and benzo[b]acronycine. In contrast with what is observed in the pyridoacridone and benzopyridoacridone series, the linear benzo[b]-pyrano[2,3-i]xanthen-6-one derivatives were more potent than their angular benzo[b]pyrano[3,2-h]xanthen-7-one isomers. cis-3,4-Diacetoxy-5-methoxy-2,2-dimethyl-3,4-dihydro-2H,6H-benzo[b]pyrano[2,3-i]xanthen-6-one, the most active among the new compounds, was more potent than acronycine in inhibiting the proliferation of L1210 murine leukemia cells.

2,2-Dimethyl-2H-anthra[2,3-b]pyran-6,11-diones: a new class of cytotoxic compounds.

The synthesis and cytotoxic activity of some new 2,2-dimethyl-2H-anthra[2,3-b]pyran-6,11-diones is described. Certain compounds possess interesting activity against murine leukemia L-1210 cells. Relationships between the biological activity and the pyrano-ring conformations are discussed.

From peptide libraries to optimized nonpeptide ligands in the search for S-farnesyltransferase inhibitors.

A complete 331,776-member library of tetrapeptides made of 24 amino acid building blocks was synthesized robotically on solid phase and subjected to a deconvolution based on the inhibitory potency of the sublibraries in a HPLC assay of the S-farnesyltransferase activity in vitro. One of the non-natural peptide and noncysteine-containing leads Nip-Trp-Phe-His (Nip=p-nitrophenyl-L-alanine) was optimized chemically to give a proteolytically stable pseudopeptide with a 200-fold potency compared with the original lead. The final compound was converted to the C-terminal ethyl ester: p-F-C6H4-CO(CH2)2-CO-Bta-D-Phepsi[CH2NH]His-OEt (Bta = benzothienyl-L-alanine) and shown to behave as a prodrug which was hydrolyzed back to the C-terminal acid following cell penetration. The method confirmed that several structurally original leads can be discovered in large libraries when deconvolution relies upon a highly specific assay and that these leads can be optimized by chemical modification to impart the final compound the desired pharmacological and pharmacokinetic properties.

General synthesis of alpha-substituted 3-bisaryloxy propionic acid derivatives as specific MMP inhibitors.

Modulations of alpha and aryl substitutions on 3-aryloxy propionic acid hydroxamates led to novel and potent inhibitors of MMP-2,3,9 and 13, and selectivity versus MMP-1.

Novel antitumor artemisinin derivatives targeting G1 phase of the cell cycle.

Modification of artemisinin structure led us to the discovery of a novel class of antitumor compounds. These artemisinin derivatives containing cyano and aryl groups showed potent antiproliferative effect in vitro against P388 and A549 cells. This activity was reflected in P388 murine leukemia by an accumulation of cells in G1 phase, and induction of apoptosis.

Synthesis of a novel series of cytotoxic bisindole alkaloids.

Original cytotoxic bisindole alkaloids with a 1,2,3,4-tetrahydroquinoline bridge were synthesized by reductive amination with various anilines. The most cytotoxic compounds display a high and dose-dependent cell cycle effect with accumulation in the G1 phase. Influence of substitution of the starting aniline on the reaction and on cytotoxicity of produced dimers was pointed out.

Characterization of TNP-470-induced modifications to cell functions in HUVEC and cancer cells.

The aim of the present work is to characterize (both in vitro and in vivo) the influence of TNP-470 on different cell functions involved in angiogenesis and, more particularly, on endothelial cell growth, cell migration and vessel formation. In addition, a possible direct anti-tumor activity was investigated. To this end, we made use in vitro of human umbilical cord endothelial vein (HUVEC) cells and two human cancer cell lines. The TNP-470 effects on the growth of cancer cell lines were compared to those of Taxol (an inhibitor of microtubule depolymerization), a cytotoxic reference which also displays strong antiogenic activity at low (non-toxic) doses. The in vitro effects were characterized on the mouse mammary MXT adenocarcinoma, on which we also characterized the influence of three clinically active anti-tumor compounds (as cytotoxic references). The purpose of this part of the study was to determine the actual TNP-470-related anti-tumor activity and to evaluate the possible toxic side-effects at the doses at which this compound induces tumor growth inhibition. These investigations were completed by analyzing the TNP-470 effects on HUVEC cell motility and in vitro and in vivo vessel formation. The results show that in vitro, TNP-470 inhibited the growth not only of HUVEC, but also of neoplastic cells. Furthermore, TNP-470 clearly inhibited in vitro endothelial cell motility (p<10(-5)). However, it had only a minor effect (p=0.02) on the formation of HUVEC cell networks on Matrigel(R). In vivo, TNP-470 was able to inhibit tumor growth (on the MXT model) at a dose (50 mg/kg) associated with toxic side-effects. Histological examination showed a significant inhibition of vessel formation (p<0.001) at high (toxic) and intermediary (non-toxic) doses (50 and 20 mg/kg). However, we also observed that TNP-470 stimulated lymphocyte proliferation. Thus, care must be taken with the TNP-470 compound in combination with other anti-tumoral agents in order to avoid certain unfortunate clinical complications.

In vitro and in vivo pharmacological characterizations of the antitumor properties of two new olivacine derivatives, S16020-2 and S30972-1.

S16020-2, a new olivacine derivative and a topoisomerase II inhibitor, has recently entered clinical trials. New analogues and derivatives have been synthesized from the S16020-2 compound. Preliminary data indicate that S30972-1, one of these S16020-2 derivatives, may exhibit a comparatively higher level of antitumor potency associated with an improved therapeutic index than does S16020-2. The antitumor activities of S16020-2 and S30972-1 were therefore characterized both in vitro and in vivo, with Adriamycin and etoposide chosen as reference compounds. The in vitro data show that S30972-1 is a topoisomerase II inhibitor, mediating its activity through an ATP-dependent mechanism such as S16020-2. The two olivacine derivatives exhibited similar activities in vitro at the levels of the global growth of six human cancer cell lines, of the induction of apoptosis, and of the G2 cell cycle phase arrest. The in vivo antitumor activity characterization included the use of two murine leukemia types (P388-LEU and L1210-LEU), two murine lymphoma-like models (P388-LYM and L1210-LYM), two mammary adenocarcinomas (MXT-HI and MXT-HS), and one melanoma (B16). The data show that S30972-1 is actually more efficient in vivo than S16020-2, a feature that may relate to the fact that S30972-1 is less toxic than S16020-2. The S30972-1 compound exhibited in vivo a level of antitumor activity that was also actually higher than that exhibited by Adriamycin and similar to that exhibited by etoposide.

Eriochrome Black T inhibits endothelial cell growth through S-phase blockade.

We used human umbilical vein endothelial cells (HUVEC) cultures to investigate in vitro the antiproliferative effects of suramin and of its analogue, Eriochrome Black T. The cell cycle phases of interest were characterised with specific immune sera raised against cyclin D(1), cyclin E and proliferating nuclear cell antigen (PCNA). Simultaneous detection of two cell cycle markers was ensured by double colour immunofluorescence. Both compounds inhibited the endothelial cell growth while Eriochrome Black T was more potent than suramin. Suramin induced HUVEC to accumulate in G1-phase as an increase of the number of cells expressing both cyclin D(1) and PCNA was observed. Eriochrome Black T preferentially blocked them in the early S-phase, as it increased the proportion of cyclin E positive cells. These results suggest that in addition of its more potent antiproliferative effect on endothelial cell growth, Eriochrome Black T acts at another molecular level than suramin.

Synthesis and cytotoxic and antitumor activity of benzo[b]pyrano[3, 2-h]acridin-7-one analogues of acronycine.

Benzo¿bacronycine (6-methoxy-3,3,14-trimethyl-3, 14-dihydro-7H-benzo¿bpyrano¿3,2-hacridin-7-one, 4), an acronycine analogue with an additional aromatic ring linearly fused on the natural alkaloid basic skeleton, was synthesized in three steps, starting from 3-amino-2-naphthalenecarboxylic acid (5). Eight 1, 2-dihydroxy-1,2-dihydrobenzo¿bacronycine esters and diesters (17-24) were obtained by catalytic osmic oxidation, followed by acylation. All these compounds were significantly more cytotoxic than acronycine, when tested against L1210 leukemia cells in vitro. The potency of the cyclic carbonate 24 was in the range of the most active drugs currently used in cancer chemotherapy. Two selected diesters (17 and 24) were evaluated in vivo against P388 leukemia and colon 38 adenocarcinoma implanted in mice. Both compounds were markedly active at doses 16-fold lower than the dose of acronycine itself. Against colon 38 adenocarcinoma, compounds 17 and 24 were highly efficient, inhibiting tumor growth by more than 80%. Diacetate 17 was the most active, inhibiting tumor growth by 96% at 6.25 mg/kg, with two of seven mice being tumor-free on day 43.

Expression of vascular endothelial growth factor (VEGF) and VEGF receptors in human neuroblastomas.

BACKGROUND: Vascular endothelial growth factor (VEGF) is a specific endothelial cell mitogen that stimulates angiogenesis and plays a crucial role in tumor growth. The aim of the present study was to evaluate the expression of VEGF and of its two high-affinity tyrosine kinase receptors (KDR and Flt-1) in neuroblastoma surgical samples and cell lines. PROCEDURE: The VEGF, KDR, and Flt-1 mRNA expression in neuroblastoma surgical samples and cell lines was studied by RT-PCR. The receptors were identified in [(125)I]VEGF binding and in functional studies (effect on cell growth). VEGF production by neuroblastomas was investigated by the ELISA method. RESULTS: It was possible to observe the mRNAs encoding for VEGF and its two receptors in some of the surgical specimens examined, including most of the high-grade tumors. It was also possible to demonstrate that the SK-N-BE cell line expressed VEGF, KDR, and Flt-1 mRNAs as well as biologically active receptors: The cells bound [(125)I]-VEGF, and their growth was stimulated by exogenous VEGF. Moreover, VEGF protein could be detected in their culture conditioned medium. CONCLUSIONS: These results suggest that, in addition to its effect on angiogenesis, VEGF may affect neuroblastoma cell growth directly and could be an autocrine growth factor.

Design, synthesis and biological activity of 7-O-(4-O-acetyl-3-iodo-2,3,6-trideoxy-alpha-L-arabino-hexopyranosyl) daunomycinone and 7-O-(3-chloro-2,3,6-trideoxy-4-O-propanoyl-alpha-L-lyxo- hexopyranosyl)daunomycinone.

The synthesis and pharmacological evaluation of 7-O-(4-O-acetyl-3-iodo-2,3,6-trideoxy-alpha-L-arabino-hexopyranosyl) daunomycinone and 7-O-(3-chloro-2,3,6-trideoxy-4-O-propanoyl-alpha-L-lyxo-hexopyrano syl) daunomycinone are described. Their cytotoxic activity was evaluated against normal and resistant cell lines. Both compounds exhibited activity against the adriamycin resistant cell line KB-A1. These results support the hypothesis that the increased lipophilicity of the sugar part of anthracyclines is associated with their ability to overcome multidrug resistance (MDR).