Activation of phospholipase D activity in transforming growth factor-beta-induced cell growth inhibition

Cells regulate phospholipase D （PLD） activity in response to numerous extracellular signals. Here, we investigated the involvement of PLD activity in transforming growth factor-β（TGF-β1）-mediated growth inhibition of epithelial cells. TGFβ1 inhibits the growth of MDCK, Mv1Lu, and A-549 cells. In the presence of 0.4 % butanol, TGF-β1 induces an increase in the formation of phosp hat idylbutanol, a unique product catalyzed by PLD. TGF-β1 also induces an increase in phosphatidic acid （PA） level in A-549 and MDCK cells. TGF-β1 induces an increase in the levels of DAG labeled with [3H]-myristic acid in A-549 and MDCK cells but not in Mv1Lu cells- No increase of DAG was observed in cells prelabeled with [3H]-arachidonic acid.The data presented suggest that PLD activation is involved in the TGF-β1-induced cell growth inhibition.