Growth factors promote inositol uptake in BC3H1 cells

BC3H1 cells induced to differentiate by serum withdrawal were found to incorporate substantially less [3H]inositol into their phosphoinositides than cells induced to differentiate by growth in the presence of high serum. This decrease was found to be due to a decline in the rate of [3H]inositol uptake by the serum-starved cells. Addition of purified growth factors such as TGF-beta, EGF and FGF to these cells promoted inositol uptake and lead to an increase in the incorporation of [3H]inositol into phosphoinositides. Stimulation of inositol uptake by TGF-beta required at least a 24 hr exposure to the growth factor. These data indicate that growth factors regulate phosphoinositide metabolism at many different levels including at the level of inositol uptake.