Downregulation of SOK1 promotes the migration of MCF-7 cells

SOK1 is a member of the germinal center kinase (GCK-III) subfamily but little is known about it, particularly with respect to its role in signal transduction pathways relative to tumor metastasis. By stably transfecting SOK1 siRNA into the MCF-7 breast cancer cell line we found that SOK1 promotes the migration of MCF-7 cells, as determined using wound-healing and Boyden chamber assays. However, cell proliferation assays revealed that silencing SOK1 had no effect on cell growth relative to the normal cells. Silencing SOK1 also had an effect on the expression and phosphorylation status of a number of proteins in MCF-7 cells, including FAK and GM130, whereby a decrease in SOK1 led to an increase in the expression of these proteins.     

Cellular internalization and stress response of ingested amorphous silica nanoparticles in the midgut of Drosophila melanogaster

Background

Amorphous silica nanoparticles (aSNPs) are used for various applications including food industry. However, limited in vivo studies are available on absorption/internalization of ingested aSNPs in the midgut cells of an organism. The study aims to examine cellular uptake of aSNPs (< 30 nm) in the midgut of Drosophila melanogaster (Oregon R⁺) owing to similarities between the midgut tissue of this organism and human and subsequently cellular stress response generated by these nanoparticles.

Methods

Third instar larvae of D. melanogaster were exposed orally to 1–100 μg/mL of aSNPs for 12–36 h and oxidative stress (OS), heat shock genes (hsgs), membrane destabilization (Acridine orange/Ethidium Bromide staining), cellular internalization (TEM) and apoptosis endpoints.

Results

A significant increase was observed in OS endpoints in the midgut cells of exposed Drosophila in a concentration- and time-dependent manner. Significantly increased expression of hsp70 and hsp22 along with caspases activation, membrane destabilization and mitochondrial membrane potential loss was also observed. TEM analysis showed aSNPs-uptake in the midgut cells of exposed Drosophila via endocytic vesicles and by direct membrane penetration.

Conclusion

aSNPs after their internalization in the midgut cells of exposed Drosophila larvae show membrane destabilization along with increased cellular stress and cell death.

General significance

Ingested aSNPs show adverse effects on the cells of GI tract of the exposed organism thus their industrial use as a food-additive may raise concern to human health.