Activation of PKR inhibits the motility of breast cancer cells.

<p><b>A</b>: MDA-MB231 cells (5x10⁴) were placed into the upper compartments of migration chambers (transwells) in the presence of PIC (0, 5 and 10 ng/ml). The transwells were incubated at 37°C in 5% CO₂ overnight. The number of migrated MDA-MB231 cells was measured as described under the Materials and Methods. <b>B</b>: The number of migrated BT474 and SKBR3 cells in the presence of PIC treatment (0 or 10 ng/ml) was determined as described above. <b>C</b>: The expression of phosphorylated PKR and total PKR in MCF7, MB231, BT474 and SKRB3 cells were determined by immunoblotting. <b>D</b>: MDA-MB231 cells were exposed to PIC (0, 5 and 10 ng/ml) for 36 h and cell migration was determined by wound healing migration assay as described under the Materials and Methods. <b>E</b>: MDA-MB231 cells were exposed to PIC (0, 5, 10, 50 or 100 ng/ml) with/without serum for 24 and 36 h. The cell viability was determined with MTT assay. The number of viable cells after PIC treatment was presented relative to untreated controls. <b>F</b>: MDA-MB231 cells were treated with PIC (0 or 10 ng/ml) for indicated time courses. Cell lysates were collected for immunoblotting analysis of the phosphorylation/expression of PKR and eIF2α. The expression of GAPDH served as a loading control. <b>G</b>: The relative levels of pPKR and pelF2α were quantified as described under the Materials and Methods and normalized to the expression of PKR and elF2α, respectively. Each datum point was the mean ± SEM of three independent experiments. * denotes a statistically significant difference from untreated controls (p<0.05).