Interferon-gamma activates the voltage-gated calcium channel in RPMI 4788 cells

Interferon (IFN) increases cytoplasmic free calcium ([Ca2+]i) in RPMI 4788 cells, a human colon cancer cell line. Addition of IFN to the cells loaded with Fura-2, a fluorescent Ca2+ indicator, causes an immediate increase in [Ca2+]i, which is the earliest event after IFN stimulation. A cyanine dye, dis-C3- (5) was used to determine the effects of IFN on the membrane potential in cancer cells. The depolarization was seen with IFN-gamma, but not with IFN-beta. These results taken together, suggest that the IFN-gamma and -beta induced [Ca2+]i mobilization are clearly different in their dependence on Ca2+ entry through voltage-gated Ca2+ channels.