Background and objective: MDA-MB-468 breast carcinoma cells respond to non-volatile anaesthetics such as propofol with an increased migration. Here we investigated the relationship between GABA-A receptor modulators, the mode of calcium oscillation and actin reorganization with regard to breast carcinoma cell migration.
Methods: Expression of the GABA-A receptor was determined by Western blot analysis. Calcium-imaging experiments of individual MDA-MB-468 cells as well as visualization of the F-actin distribution were performed by confocal laser scanning microscopy. Cell migration was investigated in a three-dimensional collagen matrix by time-lapse video microscopy. The GABA agonist propofol was used in a final concentration of 6 microg mL(-1). GABA-A receptor antagonist bicuculline (50 micromol) and selective L-type calcium channel blocker verapamil (5 micromol) were used to modulate the propofol effects.
Results: A functional GABA-A receptor is expressed by MDA-MB-468 cells. Activation with propofol resulted in sustained increased intracellular calcium concentrations concomitant with actin reorganization and induction of migration in MDA-MB-468 cells. These propofol effects were completely blocked by verapamil. Spontaneous migration of MDA-MB-468 cells (64.4 +/- 7.0%) was significantly increased by propofol to 85.0 +/- 5.0%. MDA-MB-468 cells co-treated with propofol and verapamil showed a migratory activity of 63.0 +/- 2.0% indicating that verapamil blocked the propofol effect. Similar results were achieved with the GABA-A receptor inhibitor bicuculline (control: 56.3 +/- 8.5%; propofol: 80.5 +/- 7.1%; propofol + bicuculline: 52.5 +/- 8.6%).
Conclusion: Activation of GABA-A receptor by propofol correlated with an increased migration of MDA-MB-468 breast carcinoma cells, mediated by calcium influx via L-type calcium channels and reorganization of the actin cytoskeleton.