Cellular uptake of fluorescent labelled biotin-streptavidin microspheres.

Amino functionalized, cross-linked, polystyrene microspheres were covalently loaded with streptavidin to which was coupled fluorescently labeled biotin and biotinylated-tagged DNA. These biotin-streptavidin microsphere conjugates were then successfully delivered into cells. The application of the streptavidin-biotin technology to these microspheres allows the effective delivery of any biotinylated material into intact mammalian cells, without the need for delicate procedures such as micro-injection.

(Q)SAR studies to design new human choline kinase inhibitors as antiproliferative drugs.

Most of the signal transduction pathways are mediated by protein kinases regulating every aspect of cell function. Mutations which deregulate their expression or their function or both result in cancers. Therefore, protein kinase inhibitors have become the focus of development of new therapies for cancer. A comprehensive review of Choline kinase (ChoK) was published by us in 2003. Since then, molecular information of ChoK inhibitors has been accumulated. In this review, we intend to summarize the new lines of evidence that will include the design of the most active antiproliferative agents so far described against ChoK. Studies have been aimed at the establishment of structure-activity relationships and the structural parameters that define ChoK inhibitory and antiproliferative activities of a set of twenty-five acyclic biscationic pyridophane and forty acyclic biscationic quinolinephane compounds. The corresponding QSAR equation was obtained for the whole set of bisquinolinium compounds for the antiproliferative activity, taking into consideration the electronic parameter sigma(R) of R(4), the molar refractivity (MR) of R(8), and the lipophilic parameters clog P and pi(linker). The most potent antiproliferative agent shows an IC(50) = 0.45 microM, predicted by the QSAR equation, whilst its experimental value is IC(50) = 0.20 microM. Finally, toxicity assays were performed for the most promising compounds because of their interesting antiproliferative activities [IC(50 HT-29) = 0.70, 0.80, 1.50 and 1.90 microM] and low toxicity [LD(50) = 16.7, 12.5, > 25 and > 20 mg/kg of mouse]. These biological activities justify further analysis for antitumoral assays under in vivo conditions.

QSAR-derived choline kinase inhibitors: how rational can antiproliferative drug design be?

This review presents an overview of Choline Kinase (ChoK) inhibitors with antiproliferative activity. The consideration of ChoK as a novel target for the development of new anticancer drugs is justified. The synthesis of several derivatives based on structural modifications of hemicholinium-3 (HC-3) is not accompanied by potentiation of the neurological toxicity of HC-3. The increment of both ChoK inhibitory and antiproliferative activities was successfully obtained by the two following changes: a) substitution of the oxazonium moiety of HC-3 by several aromatic heterocycles, and b) using the 1,2-ethylene(bisbenzyl) moiety instead of the 4,4'-biphenyl fragment. In an attempt to understand the ChoK inhibitory activity, a quantitative structure-activity relationship was developed. The QSAR equations have described the forces involved in quantitative terms. The electron characteristic of the substituent at position 4 of the heterocycle and the lipophilic character of the whole molecule were found to significantly affect the antitumour activity in compounds 17-95. Trispyridinium compounds 91-95 are more potent than the bispyridinium ones 87-89 as ChoK inhibitors. Nevertheless, 91-95 are less active than 87-89 as antiproliferative agents because the latter show better lipophilicities to cross the cytosolic membranes. Inhibition of the growth of human tumours in nude mice has been demonstrated: Antitumour activity of compound 64 against human HT-29 produced a decrease of up to 70% in the size of the tumour in nude mice. These results indicate that ChoK can be used as a general target for anticancer drug design against Ras-dependent tumourigenesis.