Fatty acid composition and CD36 expression in breast adipose tissue of premenopausal and postmenopausal women

The mammary gland is an organ under complex hormonal and developmental regulation. Among the mediators involved in this process are polypeptides, steroid hormones and certain lipids and their metabolites. The fatty acid content of the breast adipocytes is investigated because of the importance of their role in the proliferation and differentiation of the breast epithelial cells.

To address the hypothesis that polyunsaturated acid might be a risk factor for breast cancer, we examined the association between arachidonic acid (20:4n-6) and menopausal status in the women using lipid extraction from isolated human adipocytes and CD36 detection on a FACS flow cytometer.

Compared with the related trigycerides, phospholipids in postmenopausal women contained a higher proportion of polyunsaturated fatty acids like arachidonic acid, a precursor of eicosanoids, required for many physiological roles in reproduction and implicated in the proliferation of several cell types. In order to determine the mechanisms explaining the difference in the fatty acid and long-chain fatty acid composition, we have studied the relationship between CD 36 protein and menopausal status. Menopause in women seemed to be associated with a diminuation of the amount of CD 36 protein of adipocytes (48.82 +/- 3.54% versus 20.01 +/- 0.04%) and also associated with the increased percentage of arachidonic acid observed in postmenopausal women. Our data and others led us to conclude that the variation in the composition of fatty acids can act directly on the phenomena of growth and differentiation of mammary epithelial cells and the variation in CD 36 may act either on the transport of fatty acids or on the transduction of the signal responsible for the stimulation of enzymes catalysing the conversion of arachidonic acid into different metabolites. These two phenomena could influence the risk of breast cancer in pre- and postmenopausal women.