cytochalasin-d and tubulazole

Cytoskeletal agents have been demonstrated to inhibit stimulated motility and substrate adherence by the human tumor cell line, A2058. cis-tubulozole, taxol, and cytochalasin D were tested for their effects on chemotaxis in response to a tumor cytokine, autocrine motility factor, and on adherence to several substrata: laminin- and gelatin-coated dishes as well as tissue culture plastic. Cytochalasin D, which inhibits microfilament polymerization, abolished stimulated motility. Taxol, which stabilizes microtubules, decreased stimulated motility to a greater degree than cis-tubulozole, which inhibits microtubular polymerization. In contrast, cis-tubulozole had the greatest inhibitory effect on adherence with a gelatin substratum more affected (100% inhibition) than tissue culture plastic (90%) or laminin substratum (52%). Taxol affected adherence in the same order but less than cis-tubulozole. Cytochalasin D had no significant effect on adherence to laminin with moderate inhibition of adherence to tissue culture plastic or gelatin. These data suggest that, in these tumor cells, microfilaments are more crucial for motility than adherence, but the dynamic polymerization and depolymerization of microtubules are required for both types of cellular activities.

Topics: Antineoplastic Agents; Cell Adhesion; Cell Movement; Chemotaxis; Cytochalasin B; Cytochalasin D; Cytoskeleton; Dioxolanes; Humans; Paclitaxel; Tumor Cells, Cultured

Fertilized eggs of the leech Helobdella triserialis undergo a cytoplasmic reorganization which generates domains of nonyolky cytoplasm, called teloplasm, at the animal and vegetal poles. The segregation of teloplasm to one cell of the eight-cell embryo is responsible for a unique developmental fate of that cell, i.e., to give rise to segmental ectoderm and mesoderm. We have studied the cytoplasmic movements that generate teloplasm using time-lapse video microscopy; the formation and migration of rings of nonyolky cytoplasm were visualized using transmitted light, while the movements of mitochondria into these rings were monitored with epifluorescence after labeling embryos with rhodamine 123, a fluorescent mitochondrial dye. To examine the likelihood that cytoskeletal elements play a role in the mechanism of teloplasm formation in Helobdella, we examined the distribution of microtubules and microfilaments during the first cell cycle by indirect immunofluorescence and rhodamine-phalloidin labeling, respectively. The cortex of the early embryo contained a network of microtubules many of which were oriented parallel to the cell surface. As teloplasm formation ensued, microtubule networks became concentrated in the animal and the vegetal cortex relative to the equatorial cortex. More extensive microtubule arrays were found within the rings of teloplasm. Actin filaments appeared in the form of narrow rings in the cortex, but these varied apparently randomly from embryo to embryo in terms of number, size, and position. The role of microtubules and microfilaments in teloplasm formation was tested using depolymerizing agents. Teloplasm formation was blocked by microtubule inhibitors, but not by microfilament inhibitors. These results differ significantly from those obtained in embryos of the oligochaete Tubifex hattai, suggesting that the presumably homologous cytoplasmic reorganizations seen in these two annelids have different cytoskeletal dependencies.

Topics: Actin Cytoskeleton; Animals; Benzimidazoles; Cytochalasin D; Cytochalasins; Dioxolanes; Embryo, Nonmammalian; Leeches; Microtubules; Nocodazole; Oligochaeta; Species Specificity; Videotape Recording