Effect of transforming growth factor‐α on inositol phospholipid metabolism in human epidermoid carcinoma cells

Publisher Website
Google Scholar
Abstract
Transforming growth factor‐α (TGF‐α) stimulates (in a dose‐dependent manner) the incorporation of [32P]Pi into phosphatidylinositol(PI), phosphatidylinositol 4‐phosphate (PIP), phosphatidylinositol 4,5‐bisphosphate (PIP2), and phosphatidic acid (PA) in the human epidermoid carcinoma cell line (A431). The effect of TGF‐α on the incorporation was found to be similar to that of EGF. On the other hand, a striking difference in the activation of diacylglycerol (DG) kinase activity was seen between TGF‐α and EGF. At least 100 times more TGF‐α was required to achieve maximal stimulation of DG kinase activity relative to EGF. These results suggest that the activation of DG kinase by TGF‐α may involve a mechanism independent from or subsequent to activation of the EGF receptor.