Blockage of Volume-Activated Chloride Channels Inhibits Migration of Nasopharyngeal Carcinoma Cells

Abstract

Cell migration is crucial for tumor metastasis. Membrane ion channels may play a major role in tumor cell migration because the cells must undergo changes in shape and volume during migration. In the present study, we used the transwell migration assay, an in vitro model for cell migration, and the patch-clamp technique to investigate the role of the volume-activated Cl- current (Icl,vol) in the regulation of the migration of nasopharyngeal carcinoma CNE-2Z cells. 5-Nitro-2- (3-phenylpropylamino) benzoic acid (NPPB) inhibited the Icl,vol and the migration of CNE-2Z cells with almost identical dose-dependent pattern (IC50 of 98.1 µM and 97.7 µM for Icl,vol and cell migration, respectively). Extracellular adenosine triphosphate (ATP) also showed similar dose-dependent inhibitory effects on the currents and migration (IC50 of 1.07mM, and 1.11mM for Icl,vol and cell migration, respectively). Hypotonic treatments, which activated Icl,vol, increased cell migration. Exposure to hypertonic solutions, which was shown to suppress Icl,vol, inhibited cell migration. Replacement of Cl- with gluconate, which is relatively chloride channel-impermeable, impaired cell migration, whereas substitution of Cl- by I- and Br-, the chloride channel-permeable ions, did not significantly affect cell migration. Analysis of the effects of all the above treatments on Icl,vol and cell migration indicated that the inhibition of migration was positively correlated with the blockage of Icl,vol, with a correlation coefficient (r) of 0.97, suggesting a functional relationship between Icl,vol and cell migration. These data suggest that the volume-activated Cl- channels are involved in cell migration.