KCa2.3 channel-dependent hyperpolarization increases melanoma cell motility

Cell migration and invasion are required for tumour cells to spread from the primary tumour bed so as to form secondary tumours at distant sites. We report evidence of an unusual expression of KCa2.3 (SK3) protein in melanoma cell lines but not in normal melanocytes. Knockdown of the KCa2.3 channel led to plasma membrane depolarization, decreased 2D and 3D cell motility. Conversely, enforced production of KCa2.3 protein in KCa2.3 non-expressing cells led to the plasma membrane becoming hyperpolarized, and enhanced cell motility. In contrast, KCa3.1 channels had no effect on cell motility despite an active role in regulating membrane potential. Our data also suggest that membrane hyperpolarization increases melanoma cell motility and that this occurs through the KCa2.3 channel. Our findings reveal a previously unknown function of the KCa2.3 channel, and suggest that the KCa2.3 channel might be the only member of the Ca2+-activated K+ channel family involved in melanoma cell motility pathways.