DIFFERENTIATION-INDUCING FACTOR OF D-DISCOIDEUM RAISES INTRACELLULAR CALCIUM-CONCENTRATION AND SUPPRESSES CELL-GROWTH IN RAT PANCREATIC AR42J CELLS

DIF (differentiation-inducing factor) is a putative morphogen that induces stalk cell differentiation in the lower eukaryote, Dictyostelium discoideum. In this study, we have examined the effects of DIF on growth and the intracellular calcium concentration ([Ca2+](i)) in rat pancreatic acinar AR42J cells. Growth of AR42J cells was inhibited when DIF was present in the media, and approximately 50% growth inhibition was attained with 20 mu M DIF. DIF was also found to raise [Ca2+](i) in a dose-dependent manner (1-40 mu M), both in the presence and absence of extracellular Ca2+, These results suggest that DIF elicits both calcium influx from the extracellular space and calcium release from intracellular pool(s), thereby inhibiting cell growth in AR42J.