New more polar symmetrical bipyridinic compounds: new strategy for the inhibition of choline kinase α1.

AIM: Research of the antitumor properties of biscationic compounds has received significant attention over the last few years. RESULTS: A novel family of 1,1'-([2,2'-bipyridine]-5,5'-diylbis(methylene))bis-substituted bromide (9a-k), containing two nitrogen atoms in the linker, considered as hypothetical hydrogen bond acceptors, were synthesized and evaluated as ChoK inhibitors and their antiproliferative activity against six cancer cell lines. CONCLUSION: The most promising compounds in this series are 1,1'-([2,2'-bipyridine]-5,5'-diylbis(methylene))bis(4-(methyl(phenyl)amino)-quinolinium bromide derivatives 9g-i (analogs to RSM932A), that significantly inhibit cancer cell growth at even submicromolar concentrations, especially against leukemia cells. Compounds 9g-i also inhibit the ChoKα1 with good or moderate values, as predicted by initial docking studies. In addition, the most active compound 9h remarkably induces apoptosis in two cell lines following the mitochondrial pathway.

Discovery of a new binding site on human choline kinase α1: design, synthesis, crystallographic studies, and biological evaluation of asymmetrical bispyridinium derivatives.

Human choline kinase α (CKα) is a validated drug target for the treatment of cancer. In recent years, a large number of CK inhibitors have been synthesized, and one of them is currently being evaluated in Phase I clinical trials as a treatment for solid tumors. Here we have evaluated a new series of asymmetrical biscationic CK inhibitors by means of enzymatic, crystallographic, and antitumor studies. We demonstrate that one of these structures adopts a completely new binding mode not observed before inducing the aperture of an adjacent binding site. This compound shows antiproliferative and apoptotic effects on cancer cells through activation of caspase-3. Therefore, this study not only provides fruitful insights into the design of more efficient compounds that may target different regions in CKα1 but also explains how these compounds induce apoptosis in cancer cells.

From 5-fluorouracil acyclonucleosides to benzo-fused six- and seven-membered rings linked to pyrimidine and purine bases: the shift from differentiating anticancer agents to apoptotic inducers.

BACKGROUND: (RS)-1-{[3-(2-Hydroxyethoxy)-1-isopropoxy]propyl}-5-fluorouracil proved to be a good differentiating agent against rhabdomyosarcoma cells. OBJECTIVE: As lipophilicity is known to affect the anticancer activity, the synthesis of a wide range of 5-fluorouracil derivatives linked to benzo-fused seven-membered rings was undertaken. METHODS: The decision was then made to change 5-fluorouracil for uracil, with the prospect of finding an antiproliferative agent endowed with a new mechanism of action. Later on, pyrimidines were substituted for purines. Completing a structure-activity relationship study, a series of isosteric seven-membered derivatives were prepared. RESULTS/CONCLUSION: Finally, molecules were designed in which both structural entities (such as the benzoheterocycle and the purine) were linked through a strong C-C bond. The anticancer activity for the most active compounds was correlated with their capability to induce apoptosis.

Cellular mechanisms involved in the melatonin inhibition of HT-29 human colon cancer cell proliferation in culture.

The antiproliferative and proapoptotic properties of melatonin in human colon cancer cells in culture were recently reported. To address the mechanisms involved in these actions, HT-29 human colon cancer cells were cultured in RPMI 1640 medium supplemented with fetal bovine serum at 37 degrees C. Cell proliferation was assessed by the incorporation of [(3)H]-thymidine into DNA. Cyclic nucleotide levels, nitrite concentration, glutathione peroxidase and reductase activities, and glutathione levels were assessed after the incubation of these cells with the following drugs: melatonin membrane receptor agonists 2-iodo-melatonin, 2-iodo-N-butanoyl-5-methoxytryptamine, 5-methoxycarbonylamino-N-acetyltryptamine (GR-135,531), and the antagonists luzindole, 4-phenyl-2-propionamidotetralin, and prazosin; the melatonin nuclear receptor agonist CGP 52608, and four synthetic kynurenines analogs to melatonin 2-acetamide-4-(3-methoxyphenyl)-4-oxobutyric acid, 2-acetamide-4-(2-amino-5-methoxyphenyl)-4-oxobutyric acid, 2-butyramide-4-(3-methoxyphenyl)-4-oxobutyric acid and 2-butyramide-4-(2-amino-5-methoxyphenyl)-4-oxobutyric acid. The results show that the membrane receptors are not necessary for the antiproliferative effect of melatonin and the participation of the nuclear receptor in this effect is suggested. Moreover, the antioxidative and anti-inflammatory actions of melatonin, counteracting the oxidative status and reducing the production of nitric oxide by cultured HT-29 cells seem to be directly involved in the oncostatic properties of melatonin. Some of the synthetic kynurenines exert higher antiproliferative effects than melatonin. The results reinforce the clinical interest of melatonin due to the different mechanisms involved in its oncostatic role, and suggest a new synthetic pathway to obtain melatonin agonists with clinical applications to oncology.

Influence of the linker in bispyridium compounds on the inhibition of human choline kinase.

Studies have been aimed to establish the structure-activity relationship that define choline kinase (ChoK) inhibitory potency and antiproliferative activity of a set of 25 bispyridinium compounds with electron-releasing groups at position 4. Here we report that, according to their inhibitory activities against human ChoK, the enzymatic inhibitory potency is closely related to the size of the linker, the 3,3'-biphenyl moiety being the most suitable. The N-methylanilino and its derivatives, 4-chloro-N-methylanilino and 3,5-dichloro-N-methylanilino, render higher ChoK inhibitory and antiproliferative activities against the HT-29 human colon cancer cell line.

Growth inhibition, G(1)-arrest, and apoptosis in MCF-7 human breast cancer cells by novel highly lipophilic 5-fluorouracil derivatives.

In this study we evaluate the antitumour activity, the cell cycle arrest and apoptotic properties of novel lipophilic benzene-fused seven-membered 5-fluorouracil (5-FU) analogs in comparison to 5-FU on MCF-7 human breast cancer cells. The lipophilicities of ESB-786B, ESB-252A and ESB-928A were predicted by using the CDR option of the PALLAS 2.0 program. Cytotoxic assays were evaluated in MCF-7 cells treated with the sulforhodamine B colorimetric method. Cell cycle perturbations were studied by flow cytometry. Apoptosis was determined by both DNA fragmentation and annexin V-FITC and propidium iodide staining. The novel derivatives were more lipophilic than 5-FU and induced a marked growth inhibition, in a dose-dependent manner. After treatment with IC(50) value (ranged from 2.5 to 22 microM) for each compound, light microscopy observation showed modifications in the morphology of MCF-7 cells. In addition, the 5-FU analogs arrest cells in the G(0)/G(1) phase of the cell cycle whereas 5-FU induced arrest in S-phase. Moreover, induction of apoptosis was demonstrated by the annexin-V-based assay and confirmed using DNA fragmentation analysis on MCF-7 cells, a cell line in which the induction of DNA laddering is very difficult. The novel benzannelated seven-membered 5-FU analogs can be considered as specific apoptotic inducers. These experimental findings provide support for the use of these novel compounds as new weapons in the fight against breast cancer.

Design, synthesis, and biological activity of hybrid compounds between uramustine and DNA minor groove binder distamycin A.

The design, synthesis, characterization, DNA binding properties, and cytotoxic activity of a novel series of hybrids, namely, a molecular combination of the natural antibiotic distamycin A and the antineoplastic agent uramustine, are reported, and the structure-activity relationships are discussed. This homologous series 29-34 consisted of the minor groove binder distamycin A joined to uramustine (uracil mustard) by suitable aliphatic carboxylic acid moieties containing a flexible polymethylene chain that is variable in length [(CH(2))(n)(), where n = 1-6). All the hybrid compounds in this series exhibit enhanced activity compared to both distamycin A and uramustine derivatives 22-27 used for conjugation, giving IC(50) values in the range 7.26-0.07 microM following a 1 h exposure of human leukemic K562 cells, with maximal activity shown when n = 6. The distance between the uramustine and distamycin frame is crucial for the cytotoxicity, with compounds having linker lengths of four to six being at least 20-fold more cytotoxic than linker lengths one to three. Taq polymerase stop experiments demonstrated selective covalent binding of uramustine-distamycin hybrids to A/T rich DNA sequences, which was again more efficient with compounds 32-34 with a longer linker length. Two consequences can be derived from our study: (a) the distamycin moiety directs binding to the minor groove of A/T rich DNA sequences and, consequently, is responsible for the alkylation regioselectivity found in footprinting studies; (b) the higher flexibility due to a longer linker between the distamycin and uracil moieties allows the formation of complexes with the mustard moiety situated more deeply in the minor groove and, hence, with better alkylating properties.