Effects of inositol hexaphosphate on growth and differentiation in K-562 erythroleukemia cell line

Abstract Inositol hexaphosphate (InsP 6 ) has recently been shown to inhibit experimental cancers in vivo. Since the lower phosphorylated forms of InsP 6 are important in cell growth in a wide variety of mammalian cells, we tested the efficacy of InsP 6 in growth reduction of K-562 human erythroleukemia cells in vitro. We report that InsP 6 decreases the K-562 cell population by 19–36% (P 6 show that following treatment with InsP 6 , the concentration of intracellular [Ca 2+ ] ([Ca 2+ ] i ) is increased by 57% (P 3 and a 26% decrease (P 2 were noted 1 h following treatment with InsP 6 . Contrary to the dogma that cell division is associated with increased [Ca 2+ ] i , our data show that reduced cell growth and enhanced differentiation is associated with increased [Ca 2+ ] i and increased InsP 3 in the presence of InsP 6 .