Calcium Mobilization and Inhibition of Akt Reduced the Binding of PEO-1 Cells to Fibronectin

To investigate the effects of intracellular calcium (Ca²⁺) mobilization, β-catenin and Akt signal pathways after the binding of metastatic ovarian cells to fibronectin.

The expression levels of α4β1 and αvβ6 integrin were determined using α4, β1, αv, and β6 antibodies using flow cytometry on PEO-1 cells. The effect of [Ca²⁺]i on cell adhesion capacity was investigated using RTCA after stimulating PEO-1 cells using thapsigargin and tunicamycin. The binding rate of PEO-1 cells to fibronectin was also investigated in the presence of either different concentrations of cardamonin, which inhibits the accumulation of β-catenin, or different concentrations of FPA 124, which is a specific inhibitor for the PKB/Akt signal pathway, using RTCA.

RTCA analysis results showed that increasing [Ca²⁺]i through leakage of the calcium pool was strongly effective on PEO-1 cell binding to fibronectin. Extracellular calcium influx also reduced the binding of PEO-1 cells. Cell binding to fibronectin was also inhibited with a ratio of 64% in the presence of 100 µM cardamonin compared with untreated control cells. Finally, it was found that PKB/Akt inhibition with 15 µM FPA 124 decreased the binding of PEO-1 cells to fibronectin with a ratio of 88% compared with untreated control cells.

PEO-1 cell binding to fibronectin via integrins could be related to intracellular Ca²⁺ mobilization and Akt signaling.