Lipid composition and de novo cholesterogenesis in normal and neoplastic rat mammary tissues.

Female Wistar rats were given 5 mg of 7,12-dimethylbenz[a]anthracene (DMBA) and fed either a control diet (AIN), a 4% cholestyramine (CHST) diet, a 2% corn oil plus 18% coconut oil (saturated fat) diet, a 20% corn oil [unsaturated fatty acid (USF)] diet, or a USF + 4% cholestyramine (USF + CHST) diet. The mammary glands, tumors, livers, and sera were analyzed for lipids, de novo cholesterogenesis, and serum lecithin-cholesterol acyltransferase (LCAT) activity levels. Level and type of fat in the diet, DMBA, CHST, and length of feeding influenced the lipid composition of liver and mammary tissues. Stimulation of de novo cholesterogenesis in the mammary gland and depression in circulating LCAT activity levels correlated with the incidence and growth of mammary tumors, suggesting that stimulation of de novo cholesterogenesis plays an important role in mammary cancer development.