Synergistic potentiating effects of choline phosphate and ethanolamine on insulin-induced DNA synthesis in NIH 3T3 fibroblasts.

In NIH 3T3 fibroblasts insulin is a much less potent mitogen than platelet-derived growth factor or fibroblast growth factor. Here we demonstrate that addition of choline phosphate (1 mM) or ethanolamine (1 mM) to these fibroblasts for a prolonged (16 h) period specifically and greatly enhanced, particularly when added in combination, the stimulatory effects of both insulin and insulin-like growth factor I on DNA synthesis. The results suggest that increased production of choline phosphate and ethanolamine, often observed in tumors and carcinogen-treated cells, may promote the mitogenic activity of insulin and insulin-like growth factor I.