Axonal ultrastructural changes induced by three Vinca alkaloids, vincristine, vinblastine, and desacetyl vinblastine amide, were studied in vitro at concentrations of 0.01, 0.05, and 0.1 mM in the cat vagus nerve. Disruption of microtubules, appearance of paracrystalline structures, and increase in neurofilaments were induced by all three agents at 0.1 mM. A new type of paracrystal with an elec...

Treatment with the antitubulin vinblastine was found to disrupt the spindle system in dividing root-tip cells of common wheat, Triticum aestiuum L. Genotypes lacking the somatic association suppressor gene on 5BL, or containing the somatic-association promoter on 5BS, were found to be more sensitive to the treatment. In genetic lines carrying the somatic association suppressor, sensitivity to v...

We present a comparison of the energetics of spiral formation for two vinca alkaloids: a novel difluorinated vinorelbine derivative 20',20'-difluoro-3',4'-dihydrovinorelbine (F12158, or vinflunine) and the parent compound, vinorelbine. Vinca alkaloids are antineoplastic agents that halt cell division at metaphase by inhibiting microtubule assembly and inducing tubulin self-association into spir...

The cellular targets for estramustine, an antitumor drug used in the treatment of hormone-refractory prostate cancer, are believed to be the spindle microtubules responsible for chromosome separation at mitosis. Estramustine only weakly inhibits polymerization of purified tubulin into microtubules by binding to tubulin (Kd, approximately 30 microM) at a site distinct from the colchicine or the ...

The Vinca alkaloids are a group of widely used anticancer drugs, originally extracted from the Madagascar periwinkle, that disrupt microtubule dynamics in mammalian cells by interfering with proper assembly of α,β-tubulin heterodimers. They favor curved tubulin assemblies that destabilize microtubules and induce formation of spiral aggregates. Their binding energy profiles have been characteriz...

Cell biology and crystallographic studies have suggested a functional link between stathmin and microtubule targeting agents (MTAs). In a previous study we showed that stathmin increases vinblastine (VLB) binding to tubulin, and that conversely VLB increases stathmin binding to tubulin. This constituted the first biochemical evidence of the direct relationship between stathmin and an antimitoti...

A series of Vinca alkaloids were found to block polymerization of crude tubulin extracts of porcine brain in a dose-dependent manner. This appears to be a specific effect occurring at low concentrations of drug. The concentration of vinblastine that prevents polymerization by 50% was 4.3 x 10(-7) mole/liter for a tubulin concentration of 3.0 mg/ml, and this concentration is consistent with leve...

Dolastatin 10 is a highly cytotoxic antimitotic peptide in phase II clinical trials. Its cytotoxicity has been as much as 50-fold greater than that of vinblastine, despite quantitatively similar effects of the two drugs on tubulin polymerization. We compared uptake and efflux of radiolabeled dolastatin 10 and vinblastine in human Burkitt lymphoma CA46 cells to gain an understanding of the great...