Lauric acid is desaturated to 12:1n-3 by hepatocytes and rat liver homogenates

Total long-chain polyunsaturated n-3 fatty acids level is an independent predictive factor of breast cancer multifocality in women with positive hormone-receptors tumors

In a previous pilot study, we showed that polyunsaturated n-3 fatty acids of breast adipose tissues were associated with breast cancer multifocality. In the present study, we investigated biochemical, clinical and histological factors associated with breast cancer focality in a large cohort of women with positive hormone-receptors tumors. One hundred sixty-one consecutive women presenting with positive hormone-receptors breast cancer underwent breast-imaging procedures including a Magnetic Resonance Imaging prior to treatment. Breast adipose tissue specimens were collected during surgery of tumors. A biochemical profile of breast adipose tissue fatty acids was established by gas chromatography. Clinicopathologic characteristics were correlated with multifocality. We assessed whether these factors were predictive of breast cancer focality. We found that tumor size (OR = 1.06 95%CI [1.02-1.09], p < 0.001) and decreased levels in breast adipose tissue of long-chain polyunsaturated n-3 fatty acids (OR = 0.11 95%CI [0.01-0.98], p = 0.03), were independent predictive factors of multifocality. Low levels of long chain polyunsaturated n-3 fatty acids in breast adipose tissue appear to contribute to breast cancer multifocality. The present results reinforce the link between dietary habits and breast cancer clinical presentation.

Fatty acids of human milk - a review

The composition of human milk is the result of the evolution of mammals over millions of years. Among the most important components of milk are fatty acids. Approximately 85% are saturated and monounsaturated fatty acids - the rest are polyunsaturated one. Their role is to provide energy and immunity and to serve as buildings blocks, as well as assisting the hormonal system and the metabolism of fats, carbohydrates and proteins. The structural differences between fatty acids determine their biodiversity and give them particular physiological importance. Correct development of the nervous system, retina and other structures depend on an adequate supply of both these fatty acids during intrauterine development and in the newborn and infant stages. The fats present in milk form milk fat globules - structures that do not appear in milk formula prepared using vegetable oils. Apart from the mother's diet, other sources of fatty acids are endogenous biosynthesis in the mammary gland and the fat deposits from which the fatty acids are released. Evolution of the mother's body has also created adaptive mechanisms that adjust the amount of fatty acids in milk to the state of health and needs of the child. These mechanisms go some way to creating a buffer with regard to dietary shortages experienced by pregnant/breastfeeding women, and optimalise the composition of milk fatty acids depending on the age of the pregnant woman, the birth weight of the infant and the efficiency of the placenta during pregnancy.

The complex and important cellular and metabolic functions of saturated fatty acids

This review summarizes recent findings on the metabolism and biological functions of saturated fatty acids (SFA). Some of these findings show that SFA may have important and specific roles in the cells. Elucidated biochemical mechanisms like protein acylation (N-myristoylation, S-palmitoylation) and regulation of gene transcription are presented. In terms of physiology, SFA are involved for instance in lipogenesis, fat deposition, polyunsaturated fatty acids bioavailability and apoptosis. The variety of their functions demonstrates that SFA should no longer be considered as a single group.

Regulation of mammalian desaturases by myristic acid: N-terminal myristoylation and other modulations

Myristic acid, the 14-carbon saturated fatty acid (C14:0), usually accounts for small amounts (0.5%-1% weight of total fatty acids) in animal tissues. Since it is a relatively rare molecule in the cells, the specific properties and functional roles of myristic acid have not been fully studied and described. Like other dietary saturated fatty acids (palmitic acid, lauric acid), this fatty acid is usually associated with negative consequences for human health. Indeed, in industrialized countries, its excessive consumption correlates with an increase in plasma cholesterol and mortality due to cardiovascular diseases. Nevertheless, one feature of myristoyl-CoA is its ability to be covalently linked to the N-terminal glycine residue of eukaryotic and viral proteins. This reaction is called N-terminal myristoylation. Through the myristoylation of hundreds of substrate proteins, myristic acid can activate many physiological pathways. This review deals with these potentially activated pathways. It focuses on the following emerging findings on the biological ability of myristic acid to regulate the activity of mammalian desaturases: (i) recent findings have described it as a regulator of the Δ4-desaturation of dihydroceramide to ceramide; (ii) studies have demonstrated that it is an activator of the Δ6-desaturation of polyunsaturated fatty acids; and (iii) myristic acid itself is a substrate of some fatty acid desaturases. This article discusses several topics, such as the myristoylation of the dihydroceramide Δ4-desaturase, the myristoylation of the NADH-cytochrome b5 reductase which is part of the whole desaturase complex, and other putative mechanisms.

Involvement of stearoyl-CoA desaturase in the reduction of amidoxime prodrugs

1. This study investigates the enzymatic reduction of N-hydroxylated amidines by porcine adipose tissue and the possible involvement of stearoyl-CoA desaturase (SCD). 2. The reduction of the model substrate benzamidoxime was studied with porcine adipose tissue microsomes and partially purified SCD from SCD-enriched rat liver microsomes. 3. Inhibitor studies with these microsomal preparations using various inhibitors including anti-SCD antibody, cyanide and stearoyl-CoA supported a role for SCD in the reduction of N-hydroxylated amidines in adipose tissue. The content and activity of SCD in these microsomes was established by Western blot and SCD activity determinations. Additionally, a reconstituted system of cytochrome b(5), NADH-cytochrome b(5) reductase and partially purified SCD from SCD-enriched rat liver microsomes supported benzamidoxime reductase activity that was inhibitable by an anti-SCD antibody. 4. The results support the participation of SCD in the reduction of amidoxime prodrugs and demonstrate for the first time that SCD can also accept foreign compounds (xenobiotics) as substrates.

Saturated fatty acids: simple molecular structures with complex cellular functions

PURPOSE OF REVIEW

This review summarizes recent findings on the biological functions of saturated fatty acids. Some of these findings suggest that saturated fatty acids may have important and specific regulatory roles in the cells. Until now these roles have largely been outweighed by the negative impact of dietary saturated fatty acids on atherosclerosis biomarkers. Elucidated biochemical mechanisms like protein acylation (N-myristoylation, S-palmitoylation) and putative physiological roles are described.

RECENT FINDINGS

The review will focus on the following topics: new aspects on the metabolism of saturated fatty acids; recent reports on the biochemical functions of saturated fatty acids; current investigations on the physiological roles (elucidated and putative) of saturated fatty acids; and a discussion of the nutritional dietary recommendations (amounts and types) of saturated fatty acids.

SUMMARY

Dietary saturated fatty acids are usually associated with negative consequences for human health. Experimental results on the relationship between doses, physiological effects, specificities and functions of individual saturated fatty acids are, however, conflicting. In this context, this review describes emerging recent evidence that some saturated fatty acids have important and specific biological roles. Such data are needed to allow a balanced view in terms of potential nutritional benefits of saturated fatty acids, and, if necessary, reassessment of the current nutritional dietary recommendations.