Figure 5
The heterologous expression of NaV1.6 channels boost the invasive capacity of cervical cancer cell lines. (A) Representative images of phase contrast and fluorescent microscopy of C33A cells 36 h after co-transfection with NaV1.6 and GFP cDNAs. GFP-fluorescence indicated that 50–60% cancer cells were positively transfected. (B) Representative families of sodium currents obtained from non-transfected (black traces) and transfected C33A cells (red traces) with the NaV1.6 channel in response to 16-ms pulses that depolarized the cell membrane from −80 to +80 mV in 10-mV steps applied every 10 s from a holding potential of −100 mV. Dotted lines indicate the baseline (zero current). Shown recordings are the average of two current traces at any given membrane potential and filtered at 5 kHz. (C) Current-voltage relationship for NaV1.6 channels heterologously expressed in C33A cells. Peak Na+ currents were averaged and plotted as a function of the depolarizing potential (Vm). (D) Activation of normalized Na+ conductance. Same cells as in (C). Smooth line is the fit to a Boltzmann function (see Methods) with the following parameters: V1/2 = −12.2 ± 1.2 mV and k = 9.7 ± 1.0 mV; n = 9 cells. (E) The heterologous expression of NaV1.6 channels enhances the invasive capacity of C33A cells. Relative invasion of C33A cells transfected with NaV1.6 in absence or presence of 1 µM TTX, with respect to the control, untransfected C33A cells (black column). Columns represent the mean value of three independent experiments performed in triplicate (mean ± SD). *Statistically different from control condition (P < 0.05).
