latrunculin-a and Adenocarcinoma

Peritoneal dissemination of gastric cancer is a refractory disease. This paper focuses on the efficacy of actin-binding marine macrolide latrunculin A, which quickly inhibits actin polymerization and disrupts the function of the actin cytoskeleton. The effects of latrunculin A on cell viability in vitro were evaluated by treatment of MKN45 or NUGC-4 cell cultures. An in vitro viability assay demonstrated an anticancer effect of latrunculin A in a dose-dependent manner. Latrunculin A induced acute cell injury and programmed cell death through activating the caspase-3/7 pathway. In vivo, MKN45 or NUGC-4 cells were intraperitoneally inoculated into nude mice, as a model of peritoneal dissemination. Intraperitoneal (i.p.) injection of latrunculin A significantly improved survival rate in mice without any major side-effects. Data indicated that latrunculin A has strong anticancer effects, and it may be a new candidate i.p. drug against peritoneal dissemination of gastric cancer in humans.

Topics: Adenocarcinoma; Animals; Apoptosis; Bridged Bicyclo Compounds, Heterocyclic; Carcinoma, Signet Ring Cell; Caspases; Cell Line, Tumor; Humans; Injections, Intraperitoneal; Male; Marine Toxins; Mice; Mice, Inbred BALB C; Mice, Nude; Peritoneal Neoplasms; Stomach Neoplasms; Thiazolidines; Xenograft Model Antitumor Assays

Metastases kill 90% of cancer patients. It is thus a major challenge in cancer therapy to inhibit the spreading of tumor cells from primary tumor sites to those particular organs where metastases are likely to occur. Whereas the actin cytoskeleton is a key component involved in cell migration, agents targeting actin dynamics have been relatively poorly investigated. Consequently, valuable in vitro pharmacological tools are needed to selectively identify this type of agent. In response to the absence of any standardized process, the present work aims to develop a multi-assay strategy for screening actin-affecting drugs with anti-migratory potentials. To validate our approach, we used two cancer cell lines (MCF7 and A549) and three actin-affecting drugs (cytochalasin D, latrunculin A, and jasplakinolide). We quantified the effects of these drugs on the kinetics of actin polymerization in tubes (by means of spectrofluorimetry) and on the dynamics of actin cytoskeletons within whole cells (by means of fluorescence microscopy). Using quantitative videomicroscopy, we investigated the actual effects of the drugs on cell motility. Finally, the combined drug effects on cell motility and cell growth were evaluated by means of a scratch-wound assay. While our results showed concordant drug-induced effects on actin polymerization occurring in vitro in test tubes and within whole cells, the whole cell assay appeared more sensitive than the tube assay. The inhibition of actin polymerization induced by cytochalasin D was paralleled by a decrease in cell motility for both cell types. In the case of jasplakinolide, which induces actin polymerization, while it significantly enhanced the locomotion of the A549 cells, it significantly inhibited that of the MCF-7 ones. All these effects were confirmed by means of the scratch-wound assay except of the jasplakinolide-induced effects on MCF-7 cell motility. These later seemed compensated by an additional effect occurring during wound recolonization (possibly acting on the cell growth features). In conclusion, the use of multi-assays with different levels of sophistication and biological relevance is recommended in the screening of new actin-affecting drugs with potentially anti-migratory effects.

Topics: Actins; Adenocarcinoma; Antineoplastic Agents; Breast Neoplasms; Bridged Bicyclo Compounds, Heterocyclic; Carcinoma, Non-Small-Cell Lung; Cell Line, Tumor; Cell Movement; Cytochalasin D; Cytoskeleton; Depsipeptides; Humans; Inhibitory Concentration 50; Lung Neoplasms; Neoplasm Invasiveness; Statistics, Nonparametric; Thiazoles; Thiazolidines