Figure 1. Migration of colon cancer cells HCT-116 is dependent on calcium-activated potassium channel SK3 and SOCE.

A. SK3 channel is involved in HCT-116 cell migration. Histograms showing HCT-116 cell migration transfected for 48h with siSK3 or treated with Apamin. The normalized cell number corresponds to the ratio of total number of migrating cells in presence of drugs/total number of migrating cells in control experiments. Results are expressed as mean ± SEM. **p<0.01, sample significantly different from control (N=3, n=9, Kruskal-Wallis test). Inset, Validation of SK3 protein extinction was performed by immunoblots 48h after transfection. B. SK3 current density-voltage relation obtained in control condition or after acute treatment of Apamin. The current density-voltage relationship was obtained by dividing the averaged steady-state currents elicited between - 90mV to + 80mV by the respective cell capacitance. Results are expressed as mean ± SEM. *p=0.05, sample significantly different from control (N=4, Mann–Whitney test). C. Left panel, silencing of SK3 decreases SOCE in HCT-116 cell migration. Fluorescence measurement and relative fluorescence of Ca²⁺entry after intracellular calcium store depletion by Tg in cells transfected with siSK3 or control siRNA. Data are means ± SEM. **p<0.01, sample significantly different from control (N=7, Mann–Whitney test). Right panel, plasma membrane depolarization induces a decrease of SOCE in HCT-116 cells. Histograms showing relative fluorescence of Ca²⁺entry after intracellular calcium store depletion by Tg in HCT-116 cells in control condition or after an acute treatment with 1μM Apamin or KCl 40 mM. Data represent means ± SEM. *p<0.05, **p<0.01, sample significantly different from control (N=3, Kruskal-Wallis test) D. Orai1, TRPC1 and STIM1 promote a store operated Ca²⁺ influx. Fluorescence measurement and relative fluorescence of Ca²⁺entry after intracellular calcium store depletion by Tg in transfected cells for 48h with siOrai1, siTRPC1 and siSTIM1. Data represent means ± SEM. *p<0.05, **p<0.01, sample significantly different from control (N=6, Kruskal-Wallis test). Inset, validation of Orai1, TRPC1 and STIM1 protein extinction by siRNA was performed by immunoblots 48h after transfection. E. Calcium channels Orai1 and TRPC1 and the protein STIM1 are involved in HCT-116 migration without additive effect of apamin treatment Data represent means ± SEM. **p<0.01, ***p<0.001, sample significantly different from control (N=6, Kruskal-Wallis test).