Efficient synthesis and cell migration inhibitory effect of substituted benzamidothiazolylpyrazole-capped AWD*I-NH2

Substituted (2-benzamidothiazol-5-yl)pyrazole-capped AWD*I-NH₂ were synthesized and their antimigration activity was studied. The improved efficiency and scalability of the analog synthesis was achieved via a late-stage diversification of the benzoyl group and a convergent route in which the bisazole capping agents and off-resin peptide AWD*I-NH₂ were prepared in parallel and coupled together in solution at the last step. Bioassay results indicate that all the peptidomimetics can significantly inhibit the migration of breast cancer cells MDA-MB-231 but possess no apparent cytotoxicity. In general, the antimigration potency of the peptidomimetics is correlated to the electron-withdrawing capacity of the substituents on the terminal phenyl ring. The inhibitory effect shows dose-dependent and holds also against lung and cervical cancer cells. The level of f-actin was reduced dramatically in cells treated with the inhibitor, suggesting that the migration inhibitory effect is related to the disruption of cell locomotive protrusions.

An In Vitro Model System to Test Mechano-microbiological Interactions Between Bacteria and Host Cells

The aim of this chapter is to present an innovative technique to visualize changes of the f-actin cytoskeleton in response to locally applied force. We developed an in vitro system that combines micromanipulation of force by magnetic tweezers with simultaneous live cell fluorescence microscopy. We applied pulling forces to magnetic beads coated with the Neisseria gonorrhoeae Type IV pili in the same order of magnitude than the forces generated by live bacteria. We saw quick and robust f-actin accumulation at the sites where pulling forces were applied. Using the magnetic tweezers we were able to mimic the local response of the f-actin cytoskeleton to bacteria-generated forces. In this chapter we describe our magnetic tweezers system and show how to control it in order to study cellular responses to force.

Silver nanoparticles at sublethal concentrations disrupt cytoskeleton and neurite dynamics in cultured adult neural stem cells

Silver nanoparticles (AgNPs) have potent antimicrobial properties at concentrations far below those that cause cytotoxic and genotoxic effects in eukaryotic cells. This property has resulted in the widespread use of AgNPs in consumer products, leading to environmental exposures at sub-lethal levels through ingestion and inhalation. Although the toxicity of AgNPs has been well characterized, effects of environmentally relevant exposures have not been extensively investigated in spite of studies that suggest accumulation of silver in tissues, including brain. To assess the sublethal effects of AgNPs on neural cell function, we used cultured SVZ-NSCs, a model of neurogenesis and neural cells. Throughout life, neural stem cells (NSCs) in the subventricular zone (SVZ) of the lateral ventricles proliferate and migrate via the rostral migratory stream to the olfactory bulb. Once there, they complete differentiation into neurons and glia and integrate into existing circuits. This process of neurogenesis is tightly regulated, and is considered a part of healthy brain function. We found that 1.0 μg/mL AgNP exposure in cultured differentiating NSCs induced the formation of f-actin inclusions, indicating a disruption of actin function. These inclusions did not co-localize with AgNPs, and therefore do not represent sequestered nanoparticles. Further, AgNP exposure led to a reduction in neurite extension and branching in live cells, cytoskeleton-mediated processes vital to neurogenesis. We conclude that AgNPs at sublethal concentrations disrupt actin dynamics in SVZ-NSCs, and that an associated disruption in neurogenesis may contribute to documented deficits in brain function following AgNP exposure.