Inhibition of early platelet-derived growth factor responses in BALB/c-3T3 cells by interferon

Stimulation of total inositol phosphate production, alteration of cytosolic free calcium ( Ca++]i), vinculin disruption from adhesion plaques, and DNA synthesis caused by PDGF were examined in normal and INF pretreated density arrested BALB/c-3T3 fibroblasts. In normal cells, PDGF caused an increase in total inositol phosphates, a rapid, transient increase in Ca++]i, disappearance of vinculin from adhesion plaques, and stimulation of DNA synthesis. Pretreatment of cells with INF inhibited PDGF-stimulated increases in Ca++]i, vinculin disruption from adhesion plaques, and DNA synthesis, but had no effect on PDGF-induced increase in total inositol phosphate levels. These findings suggest that INF prevents entry of quiescent BALB/c-3T3 cells into G1 by inhibiting PDGF-induced release of Ca++ from intracellular stores.