SUPPLEMENTATION OF MCF-7 CELLS WITH ESSENTIAL FATTY-ACIDS INDUCES THEACTIVATION OF PROTEIN-KINASE-C IN RESPONSE TO IGF-1

The effects of changing the composition of membrane lipids on protein kinase C (PKC) activation were studied in MCF-7 human breast cancer ce lls. The supply of linoleate or alpha-linolenate to MCF-7 cells altere d cell membranes fatty acid composition but did not affect PKC activit y. When the cells were additionally exposed to IGF-1, the same fatty a cids caused a dramatic increase in membrane-bound PKC activity, We als o found that the mitogenic response induced by IGF-I was not enhanced in those conditions when PKC becomes activated by linoleate and alpha- linolenate. These data show that these fatty acids elicit a distinct r oute for the transmission of IGF-1 signal by inducing the PKC pathway. They suggest that linoleate and alpha-linolenate could control the bi ological response of MCF-7 cells to IGF-1. (C) 1997 Elsevier Science B .V.