Cell motility is involved in many important physiological processes, e.g. nutrition and wound healing and relies on an actin cytoskeleton shifting. However, also for tumor cells the actin cytoskeleton plays a key role in migration during metastasis and in protection from immune surveillance. This study aimed to understand cell motility and aggressive behavior in a cytoskeletal manner as a response to environmental stimuli such as magnetic fields.
PD153035 is a competitive inhibitor of the epidermal growth factor receptor. It was partially added to the culture medium to test whether the potential influence of the magnetic field is mediated via epidermal growth factor receptor-related signal pathways. Additionally, epidermal growth factor was added to the culture medium in some experiments.
Exposure duration: continuous for 30 minutes
|Exposure duration||continuous for 30 minutes|
|Setup||a pair of circular horizontal Helmholtz coil plates (20 cm in height, and 20 cm in radius, each plate consists of 150 turns of copper wire); coils were placed in a CO2 culture incubator at 37°C and shielded from external field interactions; cells and samples were placed between the plates|
|Sham exposure||A sham exposure was conducted.|
|magnetic flux density||0.4 mT||-||measured and calculated||-||± 0.012 mT|
The magnetic field exposure led to morphological changes of the cells such as new portrusions (especially filopodia and lamellipodia) in comparison to the sham exposed cells. Additionally, in exposed cells an increased population of vinculin-associated focal adhesions was found compared to the sham exposed cells. Furthermore, exposure led to an obvious reduction in the content of stress fibers in the cell centers, while larger cell surface areas and decreased efficiency of actin assembly was found in the cells, which was associated with a decrease in overall F-actin content and distributions. These effects were also associated with changes in the protein expression levels or distribution patterns of the epidermal growth factor receptor downstream motility-related signaling molecules. The effects induced by the magnetic field were similar to those provoked by adding the epidermal growth factor to the culture medium. However, blocking of the epidermal growth factor receptor activation with PD153035 did not completely prevent all magnetic field induced effects, indicating that PD153035-sensitive epidermal growth factor receptor is not the sole contributor to magnetic field-induced cytoskeletal reorganization.
The authors suggest that extremely low frequency magnetic fields influence the migration- and motility-related actin cytoskeleton reorganization and that the occurring alterations are mediated via an epidermal growth factor receptor-related signal pathway.