Docosahexaenoic acid (omega − 3) blocks voltage-gated sodium channel activity and migration of MDA-MB-231 human breast cancer cells

Omega − 3 polyunsaturated fatty acids have been suggested to play an important role in cancer prevention/progression, on the one hand, and in modulation of membrane ion channels on the other. We investigated whether docosahexaenoic acid would influence the in vitro migration of MDA-MB-231 human breast cancer cells. An important follow-up question was whether any effect would involve voltage-gated Na+ channels, shown previously to occur in human breast cancer in vitro and in vivo and to correlate with metastatic potential. Short-term (acute) and long-term (24–72 h) application of docosahexaenoic acid suppressed the activity of the channel activity in a dose-dependent manner. At the working concentrations of docosahexaenoic acid used (0.05–0.5 μM), there was no effect on proliferation. Long-term treatment with docosahexaenoic acid down-regulated mRNA and protein (total and plasma membrane) levels of neonatal Nav1.5 voltage-gated Na+ channel, known to be predominant in these cells. Docosahexaenoic acid suppressed migration of the MDA-MB-231 cells to the same extent as tetrodotoxin, a highly specific blocker of voltage-gated Na+ channels, but the two effects were not additive. It was concluded that the docosahexaenoic acid-induced suppression of cellular migration occurred primarily via down-regulation of voltage-gated Na+ channel (neonatal Nav1.5) mRNA and functional protein expression.