Supplementation of MCF-7 cells with essential fatty acids induces the activation 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 cells. The supply of linoleate or α-linolenate to MCF-7 cells altered cell membranes fatty acid composition but did not affect PKC activity. When the cells were additionally exposed to IGF-1, the same fatty acids caused a dramatic increase in membrane-bound PKC activity. We also found that the mitogenic response induced by IGF-1 was not enhanced in those conditions when PKC becomes activated by linoleate and α-linolenate. These data show that these fatty acids elicit a distinct route for the transmission of IGF-1 signal by inducing the PKC pathway. They suggest that linoleate and α-linolenate could control the biological response of MCF-7 cells to IGF-1.