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There is growing evidence that docetaxel, a microtubule-targeting agent like the other taxane paclitaxel, induces dual cytotoxicity mechanism according to dose level. Postgenomics screening technologies are now more and more applied to the elucidation of drug response mechanisms. Proton nuclear magnetic resonance spectroscopy-based pharmacometabolomics was here applied to get further insight into the response of human MCF7 breast carcinoma cells to docetaxel at high (clinical, 5 μM) and low (1 nM) doses. The global response to both doses was evaluated by nuclear morphology and DNA content, the latter as an index of cell proliferation and DNA ploidy. High dose provoked long-lasting cell cycle arrest in mitosis during the first 48 h of exposure to treatment and severe decrease in DNA content followed by significant amount of cell death. In contrast, at low dose, no long-lasting cell cycle arrest was observed on micrographies, and DNA content was decreased but less than at high dose ( P < 0.05), without significant cell death. This response was compared to biochemical alteration assessed by pharmacometabolomics. Thirty metabolites were identified and quantified. Metabolite profiling at clinical dose revealed time-dependent disorders in derivatives of glycolysis, lipid metabolism and glutathione metabolism. Comparison between high and low doses was performed at 72 h and showed common traits including the accumulation of cytidinediphosphocholine (×5.0 and ×6.9, respectively, P < 0.03), the decrease in phosphatidylcholine (×0.3 and ×0.2, respectively, P < 0.03), and gluthathione (×0.6 and ×0.6, respectively, P < 0.03). Despite that, significant dose-dependent differences were found in 12 of 30 measured metabolites. Among them, the most discriminant metabolites were polyunsaturated fatty acids (ratio of high-to-low dose of 14.8, P < 0.05), glutamate, myoinositol, and homocysteine (ratio < 0.4, P < 0.05). In addition, the mechanism for glutathione decrease was different. At high dose, it resulted from extensive consumption with precursor starvation (glutamate: −89%, P < 0.05) and increased glutathione S-transferase activity (×5, P < 0.01), whereas at low dose, it resulted from glutathione biosynthesis blockade with homocysteine accumulation (+144%, P < 0.03) and decreased glutathione S-transferase activity (−70%, P < 0.01). Altogether, this pharmacometabolomics analysis provides further evidence of the varying cellular responses at high and low doses of docetaxel in MCF7 breast cancer cells. [ABSTRACT FROM AUTHOR]

Purpose: BMS-310705, a novel semisynthetic derivative of epothilone B, is a tubulin-polymerization agent currently in phase I clinical trials for anticancer therapy. The in vitro and in vivo pharmacokinetics and oral bioavailability of BMS-310705 were investigated in mice, rats, and dogs. In addition, comparison of the pharmacokinetics of BMS-310705 using various formulations was conducted in rats. Methods: The permeability of BMS-310705 was evaluated in Caco-2 cells, an in vitro model of the human intestinal epithelium. Human liver microsomes were used to determine the cytochrome P450 enzymes involved in the metabolism of BMS-310705. Plasma protein binding of BMS-310705 was determined in mouse, rat, dog, and humans. BMS-310705 was administered to female nude mice as single doses of 5 mg/kg intravenously or 15 mg/kg orally. Male Sprague-Dawley rats were treated with single doses of BMS-310705 either intraarterially (2 mg/kg) or orally (8 mg/kg). The effect of Cremophor on the pharmacokinetics of BMS-310705 was evaluated in rats using various formulations with and without Cremophor. Male dogs were treated with 0.5 mg/kg intravenously or 1 mg/kg orally in a crossover study design. Results: Systemic clearance of BMS-310705 was high in mice (152 ml/min/kg), rats (39 ml/min/kg), and dogs (25.7 ml/min/kg). The volume of distribution (Vss) in mice, rats, and dogs was 38, 54, and 4.7 l/kg, respectively, and greater than total body water. BMS-310705 showed moderate binding to plasma proteins in all four species tested. The clearance in humans may be intermediate to high based on both allometric scaling using parameters obtained from three species, and in vitro human liver microsomal stability data. In rats, the presence of Cremophor in the formulation resulted in a significant increase in exposure compared to buffered vehicles not containing Cremophor. Inhibition of polycoprotein and/or CYP3A4 by Cremophor may be responsible for this phenomenon, and studies in Caco-2 cells and human liver microsomes suggested that BMS-310705 may be a substrate for both p-glycoprotein and CYP3A4. The oral bioavailability of BMS-310705 in pH buffered formulations was 21% in mice, 34% in rats and 40% in dogs. Conclusion: In summary, BMS-310705 is cleared rapidly and distributes extensively in mice, rats, and dogs. The presence of Cremophor in the formulation could significantly increase exposure in rats, possibly due to interactions with p-glycoprotein and/or CYP3A4. Oral bioavailability using formulations not containing Cremophor were found to be adequate, suggesting potential for development of BMS-310705 as an oral anticancer drug. [ABSTRACT FROM AUTHOR]

Purpose: Neoangiogenesis is critical to cancer proliferation and metastasis and constitutes an attractive target for cancer therapy. It has previously been demonstrated that hederacolchiside-A1 (HCol-A1), a triterpenoid saponin from Hedera colchica Koch, has antimelanoma potential. The goal of this study was to evaluate, in vitro, if in addition to its tumoricidal effect on melanoma cells, HCol-A1 might affect endothelial cell network formation. Methods: We investigated whether HCol-A1 affects matrigel-induced tubulogenesis and inhibits the viability (WST-1 assay) of human umbilical vein endothelial cells (HUVECs). To provide structure-activity relationships (SAR), studies were conducted on HCol-A1, oleanolic acid and hederacolchiside A (HCol-A), a triterpenoid saponin which possess the same sugar sequence as Hcol-A1. Plasma membrane cholesterol sequestration was studied by labelling with [3H]cholesterol and assayed with HCol- A1-cholesterol complexes. HCol-A1 signalling was investigated using immunoassays. Results: In contrast to HCol-A and oleanolic acid, HCol-A1 inhibited matrigelinduced angiogenesis at micromolar concentration. Plasma membrane cholesterol sequestration was found to be critical for this activity. Activation of the Ras/MEK/ERK cascade appears to be one of the mechanisms by which Hcol-A1 affects HUVEC network formation. The predominant activation of the Ha-Ras isoform, which decreases HUVEC-tolerance to apoptosis, might contribute to the high susceptibility of this cell line to HCol-A1. Conclusion: Since cholesterol sequestration affects cell confluence-dependent remodelling of endothelial membranes and vascular endothelial growth factor receptor-2 activity, these results raise the possibility that Hcol-A1 might slow-down cancer proliferation and metastasis in vivo by inhibiting critical aspects of neoangiogenesis. Further in vivo studies are needed to verify this hypothesis. [ABSTRACT FROM AUTHOR]

Purpose: The quaternary benzophenanthridine alkaloid sanguinarine exhibits a broad range of activity, including cytotoxicity against various human tumour and normal cell lines. Here, we examined its potency as an anticancer drug.Methods: The differential cytotoxicity against cancer versus normal cells was assessed in vitro by two fluorimetric assays (RRT and Hoechst 33342 dye DNA assays, respectively) in a panel of human solid cancer cell lines and a human fibroblast primary culture. The ability to induce apoptosis was demonstrated in PC3 human prostatic adenocarcinoma cells by analysis of morphological changes, internucleosomal DNA fragmentation, cellular poly(ADP-ribose) polymerase cleavage and caspase 3/7 activation. Production of reactive oxygen species was evaluated by the 2',7'-dichlorofluorescin diacetate assay. Depletion of cellular glutathione content was assessed with the monochlorobimane assay.Results: Sanguinarine markedly inhibited the growth of all tested cells (IC(50) 0.9-3.3 microM) without differential cytotoxicity against normal versus cancer cells. In PC3 cells, continuous treatment with 5 microM sanguinarine induced an early (within 10 min) cellular reduced glutathione depletion insensitive to dithiothreitol or N-acetylcysteine treatment, followed by a caspase 3/7-dependent apoptotic response within 2 h. Complementary assays suggested that the glutathione depletion was initiated by direct reactivity of sanguinarine with reduced glutathione.Conclusions: Taken together, these results show that (1) sanguinarine exhibits no specificity for cancer cells, and (2) its strong cytotoxicity is probably due to a rapid apoptotic response induced by an early and severe glutathione-depleting effect. They also suggest that the clinical usefulness of this alkaloid as an anticancer drug is limited. [ABSTRACT FROM AUTHOR]