A product of phosphatidylinositol-3 kinase is elevated in dividing HT29 colonic epithelial cells.

Phosphatidylinositol 3 kinase (PI-3 kinase) activity has been linked to cell proliferation and growth regulation. Therefore, we studied changes in phosphoinositide metabolism during the cell cycle of HT-29 cells, a colonic epithelial cell line. HT29 cells were treated with the microtubule disrupter, nocodozole, separated into mitotic and quiescent populations and their phospholipid composition was analyzed. Radiolabelled phospholipids from cells labelled with 32PO4 or [3H]myoinositol were analyzed by TLC and/or deacylated and analyzed by HPLC. In all cases, levels of phosphatidylinositol 3 phosphate from mitotic phase cells were double that in resting populations. Therefore, levels of a product of PI-3 kinase are elevated and may play a role in cell division.