Biosynthesis of fatty acids by lactating human breast epithelial cells: an evaluation of the contribution to the overall composition of human milk fat

Myoglobin regulates fatty acid trafficking and lipid metabolism in mammary epithelial cells

Myoglobin (MB) is known to bind and deliver oxygen in striated muscles at high expression levels. MB is also expressed at much reduced levels in mammary epithelial cells, where the protein´s function is unclear. In this study, we aim to determine whether MB impacts fatty acid trafficking and facilitates aerobic fatty acid ß-oxidation in mammary epithelial cells. We utilized MB-wildtype versus MB-knockout mice and human breast cancer cells to examine the impact of MB and its oxygenation status on fatty acid metabolism in mouse milk and mammary epithelia. MB deficient cells were generated through CRISPR/Cas9 and TALEN approaches and exposed to various oxygen tensions. Fatty acid profiling of milk and cell extracts were performed along with cell labelling and immunocytochemistry. Our findings show that MB expression in mammary epithelial cells promoted fatty acid oxidation while reducing stearyl-CoA desaturase activity for lipogenesis. In cells and milk product, presence of oxygenated MB significantly elevated indices of limited fatty acid ß-oxidation, i.e., the organelle-bound removal of a C2 moiety from long-chain saturated or monounsaturated fatty acids, thus shifting the composition toward more saturated and shorter fatty acid species. Presence of the globin also increased cytoplasmic fatty acid solubility under normoxia and fatty acid deposition to lipid droplets under severe hypoxia. We conclude that MB can function in mammary epithelia as intracellular O2-dependent shuttle of oxidizable fatty acid substrates. MB's impact on limited oxidation of fatty acids could generate inflammatory mediator lipokines, such as 7-hexadecenoate. Thus, the novel functions of MB in breast epithelia described herein range from controlling fatty acid turnover and homeostasis to influencing inflammatory signalling cascade. Future work is needed to analyse to what extent these novel roles of MB also apply to myocytic cell physiology and malignant cell behaviour, respectively.

Fatty Acid Composition of Milk from Mothers with Normal Weight, Obesity, or Gestational Diabetes

Gestation and the neonatal period are crucial periods in infant development. Many components of breast milk, including fatty acids, play an important role in strengthening the immune system. The aim of our research was to evaluate the fatty acid profiles of milk from 69 mothers, including subjects having a normal weight, obesity, or gestational diabetes. For the analyses, we used gas chromatography (GC) with flame ionization detection (FID) and GC coupled with mass spectrometry (GC/MS). The main fatty acids found in breast milk were palmitic acid (C16:0; 26-28%), linoleic acid (C18:2; 23-28%), and α-linolenic acid linoleic acid (C18:3; 15-17%), followed by myristic acid (C14:0; 5-8%), lauric acid (C12:0; 4-6%) and stearic acid (C18:0; 4-5%). The average breakdown of fatty acids was 50% saturated, 44% polyunsaturated, and 6% monounsaturated. Breast milk samples were classified using principal component analysis and linear discriminant analysis. Results showed that milk from the two major groups of obese and normal body mass index (BMI) could be distinguished with an accuracy of 89.66%. Breast milk samples of Hungarian and Ukrainian mothers showed significant differences based on the fatty acid composition, which variations are attributable to the mothers' dietary habits.

Total Fatty Acid and Polar Lipid Species Composition of Human Milk

Human milk lipids are essential for infant health. However, little is known about the relationship between total milk fatty acid (FA) composition and polar lipid species composition. Therefore, we aimed to characterize the relationship between the FA and polar lipid species composition in human milk, with a focus on differences between milk with higher or lower milk fat content. From the Norwegian Human Milk Study (HUMIS, 2002–2009), a subset of 664 milk samples were analyzed for FA and polar lipid composition. Milk samples did not differ in major FA, phosphatidylcholine, or sphingomyelin species percentages between the highest and lowest quartiles of total FA concentration. However, milk in the highest FA quartile had a lower phospholipid-to-total-FA ratio and a lower sphingomyelin-to-phosphatidylcholine ratio than the lowest quartile. The only FAs associated with total phosphatidylcholine or sphingomyelin were behenic and tridecanoic acids, respectively. Milk FA and phosphatidylcholine and sphingomyelin species containing these FAs showed modest correlations. Associations of arachidonic and docosahexaenoic acids with percentages of phosphatidylcholine species carrying these FAs support the conclusion that the availability of these FAs limits the synthesis of phospholipid species containing them.

Short-term effects of dietary bovine milk on fatty acid composition of human milk: A preliminary multi-analytical study

The fatty acid (FA) composition of human milk (HM) from N = 9 Italian healthy donors following a free diet exhibited FA-dependent ranges of variability, as assessed by GC-FID. The possible short-term changes in the FA profile were monitored in the milk of lactating mothers (three) collected at five time points over a 6 h period, following an oral load (200 mL) of bovine milk. An array of techniques was exploited, including UHPLC-ESI-MS/MS of intact lipids and MALDI-TOF MS before and after chemical hydrogenation or bromination, in addition to MALDI-TOF MS analysis of FA after saponification, to monitor short-chain and odd-chain FA in HM as markers of bovine milk fat. A single administration of bovine milk did not appreciably modify the lipid pattern, suggesting that the maternal diet could induce not detectable short-term changes on the lipid composition of HM. Diet-induced increase of butyric acid was also excluded by ¹³C NMR. The functions that HM FA exert in infant physiology appear finely regulated through maternal metabolism.

Exogenous Ketone Bodies as Promising Neuroprotective Agents for Developmental Brain Injury

Ketone bodies are a promising area of neuroprotection research that may be ideally suited to the injured newborn. During normal development, the human infant is in significant ketosis for at least the first week of life. Ketone uptake and metabolism is upregulated in the both the fetus and neonate, with ketone bodies providing at least 10% of cerebral metabolic energy requirements, as well as being the preferred precursors for the synthesis of fatty acids and cholesterol. At the same time, ketone bodies have been shown to have multiple neuroprotective effects, including being anticonvulsant, decreasing oxidative stress and inflammation, and epigenetically upregulating the production of neurotrophic factors. While ketogenic diets and exogenous ketosis are largely being investigated in the setting of adult brain injury, the adaptation of the neonate to ketosis suggests that developmental brain injury may be the area most suited to the use of ketones for neuroprotection. Here, we describe the mechanisms by which ketone bodies exert their neuroprotective effects, and how these may translate to benefits within each of the phases of neonatal asphyxial brain injury.

Crystal Structure and Substrate Specificity of Human Thioesterase 2: INSIGHTS INTO THE MOLECULAR BASIS FOR THE MODULATION OF FATTY ACID SYNTHASE

The type I fatty acid synthase (FASN) is responsible for the de novo synthesis of palmitate. Chain length selection and release is performed by the C-terminal thioesterase domain (TE1). FASN expression is up-regulated in cancer, and its activity levels are controlled by gene dosage and transcriptional and post-translational mechanisms. In addition, the chain length of fatty acids produced by FASN is controlled by a type II thioesterase called TE2 (E.C. 3.1.2.14). TE2 has been implicated in breast cancer and generates a broad lipid distribution within milk. The molecular basis for the ability of the TE2 to compete with TE1 for the acyl chain attached to the acyl carrier protein (ACP) domain of FASN is unknown. Herein, we show that human TE1 efficiently hydrolyzes acyl-CoA substrate mimetics. In contrast, TE2 prefers an engineered human acyl-ACP substrate and readily releases short chain fatty acids from full-length FASN during turnover. The 2.8 Å crystal structure of TE2 reveals a novel capping domain insert within the α/β hydrolase core. This domain is reminiscent of capping domains of type II thioesterases involved in polyketide synthesis. The structure also reveals that the capping domain had collapsed onto the active site containing the Ser-101-His-237-Asp-212 catalytic triad. This observation suggests that the capping domain opens to enable the ACP domain to dock and to place the acyl chain and 4'-phosphopantetheinyl-linker arm correctly for catalysis. Thus, the ability of TE2 to prematurely release fatty acids from FASN parallels the role of editing thioesterases involved in polyketide and non-ribosomal peptide synthase synthases.

Rapid and selective manipulation of milk fatty acid composition in mice through the maternal diet during lactation

Dietary fatty acid (FA) composition in early postnatal life can modulate growth and development and later metabolic health. Investigating programming effects of early dietary FA manipulations in rodents may be stressful and complicated due to the need of artificial feeding techniques. It is largely unknown to what extent breast milk (BM) FA composition can be directly manipulated by the diet. We exposed dams to different dietary FA compositions from postnatal day (PN) 2 until PN28. Dams with litters were randomly assigned to control (CTRL), high-medium-chain FA (MCFA), low-linoleic acid (LowLA), high-n-3 long-chain PUFA (n-3LCP) or high-n-3LCP and MCFA (n-3LCP/MCFA) diets, and diets were continued after weaning until PN28. FA compositions were determined in feeds, milk and in erythrocytes. BM MCFA content was independent from dietary MCFA intake. In contrast, the LowLA diet reduced BM LA content by about 50 % compared with the CTRL diet at PN7. BM of dams fed the n-3LCP or n-3LCP/MCFA diet contained about 6-fold more n-3 LCP than BM of the dams fed the CTRL diet at PN7. These changes in milk FA composition established after 5 d of dietary exposure did not further change over the lactation period. At PN28, the erythrocyte FA composition of the male pups correlated with analysed milk FA profiles. In conclusion, manipulation of the diet of lactating mice can strongly and rapidly affect BM FA composition, in particular of n-6 LA and n-3 LCP. Our present findings will facilitate mechanistic studies on the programming of adult metabolic health by dietary FA in the early postnatal period via direct and selective manipulation of the maternal diet.

The Dietary Composition of Women Who Delivered Healthy Full-Term Infants, Preterm Infants, and Full-Term Infants Who Were Small for Gestational Age

The impact of diet on the health of pregnant women remains an unresolved clinical issue. The aim of this study was to determine and compare the dietary intake of mothers who gave birth to full-term infants whose sizes were appropriate for gestational age (AGA), preterm birth (PTB) infants, and full-term infants who were small for gestational age (SGA). Of the 103 women who participated, 50 gave birth to AGA infants, 30 gave birth to PTB infants, and 23 gave birth to SGA infants. The composition of each woman's diet was analyzed using a questionnaire completed 3 days post-childbirth. Findings revealed a number of differences between the groups. The percentage of energy obtained from fat and the calcium and lactose intake was all highest in Group AGA. The largest number of differences in intake of fatty acids (FAs) was observed among short- and medium-chain FAs. Lower levels of C4:0, C6:0, C8:0, C10:0, and C14:0 were observed in the diets of women in Group PTB than in Group AGA. C18:0 intake was also lower in Group PTB than in Group AGA. The reduced short-, medium-, and long-chain FA intake by women in Group PTB also affected the total saturated FA intake, which was lowest in that group. These findings suggest that, even in mothers giving birth to children with only slight deviations from normal birth weight or normal gestational duration, differences in diet can be identified, particularly regarding FA content, which may affect the health of the newborn.

Inhibition of FASN reduces the synthesis of medium-chain fatty acids in goat mammary gland

Fatty acid synthase (FASN) is known as a crucial enzyme of cellular de novo fatty acid synthesis in mammary gland which has been proved as the main source of short and medium-chain fatty acids of milk. However, the regulatory role of FASN in goat-specific milk fatty acids composition remains unclear. We cloned and analyzed the full-length of FASN gene from the mammary gland of Capra hircus (Xinong Saanen dairy goat) (DQ 915966). Comparative gene expression analysis suggested that FASN is predominantly expressed in fat, small intestine and mammary gland tissues, and expresses higher level at lactation period. Inhibition of FASN activity by different concentrations (0, 5, 15, 25 and 35 μM) of orlistat, a natural inhibitor of FASN, resulted in decreased expression of acetyl-CoA carboxylase α (ACCα), lipoprotein lipase and heart-type fatty acid binding protein (H-FABP) in a concentration-dependent manner in goat mammary gland epithelial cells (GMEC). Similar results were also obtained by silencing of FASN. Additionally, reduction of FASN expression also led to apparent decline of the relative content of decanoic acid (C10:0) and lauric acid (C12:0) in GMEC. Our study provides a direct evidence for inhibition of FASN reduces cellular medium-chain fatty acids synthesis in GMEC.

De novo synthesis of milk triglycerides in humans

Mammary gland (MG) de novo lipogenesis contributes significantly to milk fat in animals but little is known in humans.

OBJECTIVE

To test the hypothesis that the incorporation of (13)C carbons from [U-(13)C]glucose into fatty acids (FA) and glycerol in triglycerides (TG) will be greater: 1) in milk than plasma TG, 2) during a high-carbohydrate (H-CHO) diet than high-fat (H-FAT) diet, and 3) during feeding than fasting. Seven healthy, lactating women were studied on two isocaloric, isonitrogenous diets. On one occasion, subjects received diets containing H-FAT or H-CHO diet for 1 wk. Incorporation of (13)C from infused [U-(13)C]glucose into FA and glycerol was measured using GC-MS and gene expression in RNA isolated from milk fat globule using microarrays. Incorporation of (13)C2 into milk FA increased with increased FA chain length from C2:0 to C12:0 but progressively declined in C14:0 and C16:0 and was not detected in FA>C16. During feeding, regardless of diets, enrichment of (13)C2 in milk FA and (13)C3 in milk glycerol were ∼ 3- and ∼ 7-fold higher compared with plasma FA and glycerol, respectively. Following an overnight fast during H-CHO and H-FAT diets, 25 and 6%, respectively, of medium-chain FA (MCFA, C6-C12) in milk were derived from glucose but increased to 75 and 25% with feeding. Expression of genes involved in FA or glycerol synthesis was unchanged regardless of diet or fast/fed conditions. The human MG is capable of de novo lipogenesis of primarily MCFA and glycerol, which is influenced by the macronutrient composition of the maternal diet.

Global gene expression in endometrium of high and low fertility heifers during the mid-luteal phase of the estrous cycle

BACKGROUND

In both beef and dairy cattle, the majority of early embryo loss occurs within the first 14 days following insemination. During this time-period, embryos are completely dependent on their maternal uterine environment for development, growth and ultimately survival, therefore an optimum uterine environment is critical to their survival. The objective of this study was to investigate whether differences in endometrial gene expression during the mid-luteal phase of the estrous cycle exist between crossbred beef heifers ranked as either high (HF) or low fertility (LF) (following four rounds of artificial insemination (AI)) using the Affymetrix® 23 K Bovine Gene Chip.

RESULTS

Conception rates for each of the four rounds of AI were within a normal range: 70-73.3%. Microarray analysis of endometrial tissue collected on day 7 of the estrous cycle detected 419 differentially expressed genes (DEG) between HF (n = 6) and LF (n = 6) animals. The main gene pathways affected were, cellular growth and proliferation, angiogenesis, lipid metabolism, cellular and tissue morphology and development, inflammation and metabolic exchange. DEG included, FST, SLC45A2, MMP19, FADS1 and GALNT6.

CONCLUSIONS

This study highlights, some of the molecular mechanisms potentially controlling uterine endometrial function during the mid-luteal phase of the estrous cycle, which may contribute to uterine endometrial mediated impaired fertility in cattle. Differentially expressed genes are potential candidate genes for the identification of genetic variation influencing cow fertility, which may be incorporated into future breeding programmes.

Differences in preterm and term milk fatty acid compositions may be caused by the different hormonal milieu of early parturition

INTRODUCTION

The hormonal milieus of pregnancy and lactation are driving forces of nutrient fluxes supporting infant growth and development. The decrease of insulin sensitivity with compensatory hyperinsulinemia with advancing gestation, causes adipose tissue lipolysis and hepatic de novo lipogenesis (DNL).

SUBJECTS AND METHODS

We compared fatty acid (FA) contents and FA-indices for enzyme activities between preterm (28-36 weeks) and term (37-42) milks, and between colostrum (2-5 days), transitional (6-15) and mature (16-56) milks. We interpreted FA differences between preterm and term milks, and their changes with lactation, in terms of the well known decrease of insulin sensitivity during gestation and its subsequent postpartum restoration, respectively.

RESULTS

Compared with term colostrum, preterm colostrum contained higher indices of DNL in the breast (DNL-breast) and medium chain saturated-FA (MCSAFA), and lower DNL-liver and monounsaturated-FA (MUFA). Preterm milk also had higher docosahexaenoic acid (DHA) in colostrum and transitional milk and higher arachidonic acid (AA) in mature milk. Most preterm-term differences vanished with advancing lactation. In both preterm and term milks, DNL-breast and MCSAFA increased with advancing lactation, while DNL-liver, MUFA, long chain SAFA and AA decreased. DHA decreased in term milk. MUFA was inversely related to MCSAFA in all samples, correlated inversely with PUFA in colostrum and transitional milks, but positively in mature milk. MCSAFA correlated inversely with PUFA in mature milk.

CONCLUSION

Higher maternal insulin sensitivity at preterm birth may be the cause of lower MUFA (a proxy for DNL-liver) and higher MCSAFA (a proxy for DNL-breast) in preterm colostrum, compared with term colostrum. Restoring insulin sensitivity after delivery may be an important driving force for milk FA-changes in early lactation.

Postdelivery changes in maternal and infant erythrocyte fatty acids in 3 populations differing in fresh water fish intakes

INTRODUCTION

Long-chain polyunsaturated (LCP) fatty acids (FA) are important during infant development. Mother-to-infant FA-transport occurs at the expense of the maternal status. Maternal and infant FA-status change rapidly after delivery.

METHODS

Comparison of maternal (mRBC) and infant erythrocyte (iRBC)-FA-profiles at delivery and after 3 months exclusive breastfeeding in relation to freshwater-fish intakes. Approximation of de-novo-lipogenesis (DNL), stearoyl-CoA-desaturase (SCD), elongation-of-very-long-chain-FA-family-member-6 (Elovl-6), delta-5-desaturase (D5D) and delta-6-desaturase (D6D)-enzymatic activities from their product/essential-FA and product/substrate-ratios.

RESULTS AND DISCUSSION

Increasing iRBC-14:0 derived from mammary-gland DNL. Decreasing mRBC-ω9, but increasing iRBC-ω9, suggest high ω9-FA-transfer via breastmilk. Decreasing (m+i)RBC-16:0, DNL- and SCD-activities, but increasing (m+i)RBC-18:0 and Elovl-6-activity suggest more pronounced postpartum decreases in DNL- and SCD-activities, compared to Elovl-6-activity. Increasing (m+i)RBC-18:3ω3, 20:5ω3, 22:5ω3, 18:2ω6, mRBC-20:4ω6 and (m+i)D5D-activity, but decreasing mRBC-22:6ω3 and (m+i)D6D-activity and dose-dependent changes in iRBC-22:6ω3 confirm that D6D-activity is rate-limiting and 22:6ω3 is important during lactation. Fish-intake related magnitudes of postpartum FA-changes suggest that LCPω3 influence DNL-, SCD- and desaturase-activities.

Inhibition of SREBP1 sensitizes cells to death ligands

Evasion of death receptor ligand-induced apoptosis contributs to cancer development and progression. To better understand mechanisms conferring resistance to death ligands, we screened an siRNA library to identify sequences that sensitize resistant cells to fas activating antibody (CH-11). From this screen, we identified the Sterol-Regulatory Element-Binding Protein 1 (SREBP1), a transcription factor, which regulates genes involved in cholesterol and fatty acid synthesis including fatty acid synthase. Inhibition of SREBP1 sensitized PPC-1 and HeLa to the death receptor ligands CH-11 and TRAIL. In contrast, DU145 prostate cancer cells that are resistant to death ligands despite expressing the receptors on their cell surface remained resistant to CH-11 and TRAIL after knockdown of SREBP1. Consistent with the effects on cell viability, the addition of CH-11 activated caspases 3 and 8 in HeLa but not DU145 cells with silenced SREBP1. We demonstrated that knockdown of SREBP1 produced a marked decrease in fatty acid synthase expression. Furthermore, genetic or chemical inhibition of fatty acid synthase with shRNA or orlistat, respectively, recapitulated the effects of SREBP1 inhibition and sensitized HeLa but not DU145 cells to CH-11 and TRAIL. Sensitization to death receptor ligands by inhibition of fatty acid synthase was associated with activation of caspase 8 prior to caspase 9. Neither silencing of SREBP1 or fatty acid synthase changed basal expression of the core death receptor components Fas, caspase 8, FADD, caspase 3 or FLIP. Thus, inhibition of SREBP1 or its downstream target fatty acid synthase sensitizes resistant cells to death ligands.

Postpartum changes in maternal and infant erythrocyte fatty acids are likely to be driven by restoring insulin sensitivity and DHA status

INTRODUCTION

Perinatal changes in maternal glucose and lipid fluxes and de novo lipogenesis (DNL) are driven by hormones and nutrients. Docosahexaenoic acid (DHA) reduces, whereas insulin augments, nuclear abundance of sterol-regulatory-element-binding-protein-1 (SREBP-1), which promotes DNL, stearoyl-CoA-desaturase (SCD, also Δ9-desaturase), fatty acid-(FA)-elongation (Elovl) and FA-desaturation (FADS). Decreasing maternal insulin sensitivity with advancing gestation and compensatory hyperinsulinemia cause augmented postprandial glucose levels, adipose tissue lipolysis and hepatic glucose- and VLDL-production. Hepatic VLDL is composed of dietary, body store and DNL derived FA. Decreasing insulin sensitivity increases the contribution of FA from hepatic-DNL in VLDL-triacylglycerols, and consequently saturated-FA and monounsaturated-FA (MUFA) in maternal serum lipids increase during pregnancy. Although other authors described changes in maternal serum and RBC essential-FA (EFA) after delivery, none went into detail about the changes in non-EFA and the mechanisms behind -and/or functions of- the observed changes.

HYPOTHESIS

Postpartum FA-changes result from changing enzymatic activities that are influenced by the changing hormonal milieu after delivery and DHA-status.

EMPIRICAL DATA

We studied FA-profiles and FA-ratios (as indices for enzymatic activities) of maternal and infant RBC at delivery and after 3 months exclusive breastfeeding in three populations with increasing freshwater-fish intakes. DNL-, SCD- and FADS2-activities decreased after delivery. Elongation-6 (Elovl-6)- and FADS1-activities increased. The most pronounced postpartum changes for mothers were increases in 18:0, linoleic (LA), arachidonic acid (AA) and decreases in 16:0, 18:1ω9 and DHA; and for infants increases in 18:1ω9, 22:5ω3, LA and decreases in 16:0 and AA. Changes were in line with the literature.

DISCUSSION

Postpartum increases in 18:0, and decreases in 16:0 and 18:1ω9, might derive from reduced insulin-promoted DNL-activity, with more reduced SCD- than Elovl-activity that leaves more 16:0 to be converted to 18:0 (Elovl-activity) than to MUFA (SCD-activity). Postpartum changes in ΣDNL, saturated-FA and MUFA related negatively to RBC-DHA. This concurs with suppression of both SCD- and Elovl-6 activities by DHA, through its influence on SREBP. Infant MUFA and LA increased at expense of their mothers. Sustained transport might be important for myelination (MUFA) and skin barrier development (LA). Maternal postpartum decreases in FADS2-, and apparent increases in FADS1-activity, together with increases in LA, AA, and 22:5ω3, but decrease in DHA, confirm that FADS2 is rate limiting in EFA-desaturation. Maternal LA and AA increases might be the result of rerouting from transplacental transfer to the incorporation into milk lipids and discontinued placental AA-utilization.

IMPLICATIONS

Perinatal changes in maternal and infant FA status may be strongly driven by changing insulin sensitivity and DHA status.

The effect of a controlled manipulation of maternal dietary fat intake on medium and long chain fatty acids in human breast milk in Saskatoon, Canada

Background

Few studies in recent years have demonstrated the effect of maternal diet on fatty acid composition of human milk.

Methods

Fourteen free-living lactating women participated in a cross-over dietary intervention study, consuming a low fat diet (17.6% of energy as fat, 14.4% of energy as protein, 68.0% of energy as carbohydrate) and a high fat diet (40.3% of energy as fat, 14.4% of energy as protein, 45.3% of energy as carbohydrate) each for periods of 4 days, in randomised order. Each mother was her own control. Mature milk samples were collected during each period and analysed for medium and long chain fatty acids.

Results

The concentration of medium chain fatty acids (MCFA), was 13.6% in breast milk for the low fat diet compared to 11.4% for the high fat (p < 0.05). Arachidonic acid (C20:4n-6) levels were significantly higher in breast milk when women consumed the low fat diet. Increased dietary intake of stearic acid (C18:0) and alpha-linolenic acid (C18:3n-3) on the high fat diet significantly increased proportions of these fatty acids in breast milk (p < 0.05) in 4 days.

Conclusions

Changing maternal dietary fat intake has a rapid response in terms of changes to fatty acids in breast milk.

Fatty acid synthase activity in tumor cells

While normal tissues are tightly regulated by nutrition and a carefully balanced system of glycolysis and fatty acid synthesis, tumor cells are under significant evolutionary pressure to bypass many of the checks and balances afforded normally. Cancer cells have high energy expenditure from heightened proliferation and metabolism and often show increased lipogenesis. Fatty acid synthase (FASN), the enzyme responsible for catalyzing the ultimate steps of fatty acid synthesis in cells, is expressed at high levels in tumor cells and is mostly absent in corresponding normal cells. Because of the unique expression profile of FASN, there is considerable interest not only in understanding its contribution to tumor cell growth and proliferation, but also in developing inhibitors that target FASN specifically as an anti-tumor modality. Pharmacological blockade of FASN activity has identified a pleiotropic role for FASN in mediating aspects of proliferation, growth and survival. As a result, a clearer understanding of the role of FASN in tumor cells has been developed.

Fatty acid synthase gene is up-regulated by hypoxia via activation of Akt and sterol regulatory element binding protein-1

The fatty acid synthase (FAS) gene is significantly up-regulated in various types of cancers, and blocking the FAS expression results in apoptosis of tumor cells. Therefore, FAS is considered to be an attractive target for anticancer therapy. However, the molecular mechanism by which the FAS gene is up-regulated in tumor cells is poorly understood. We found that FAS was significantly up-regulated by hypoxia, which was also accompanied by reactive oxygen species (ROS) generation in human breast cancer cell lines. The FAS expression was also activated by H(2)O(2), whereas N-acetyl-L-cystein, a ROS inhibitor, suppressed the expression. We also found that the hypoxia significantly up-regulated sterol regulatory-element binding protein (SREBP)-1, the major transcriptional regulator of the FAS gene, via phosphorylation of Akt followed by activation of hypoxia-inducible factor 1 (HIF1). Moreover, our results of reporter assay and chromatin immunoprecipitation analysis indicate that SREBP-1 strongly bound to the SREBP binding site/E-box sequence on the FAS promoter under hypoxia. In our xenograft mouse model, FAS was strongly expressed in the hypoxic regions of the tumor. In addition, our results of immunohistochemical analysis for human breast tumor specimens indicate that the expressions of both FAS and SREBP-1 were colocalized with hypoxic regions in the tumors. Furthermore, we found that hypoxia-induced chemoresistance to cyclophosphamide was partially blocked by a combination of FAS inhibitor and cyclophosphamide. Taken together, our results indicate that FAS gene is up-regulated by hypoxia via activation of the Akt and HIF1 followed by the induction of the SREBP-1 gene, and that hypoxia-induced chemoresistance is partly due to the up-regulation of FAS.

Lipids and infant formulas

The ultimate goal in the design of infant formula is to achieve the outcome seen in breast fed infants. This review of lipids in infant formulas for term infants begins by referring to the lipid composition of human milk, and relates that to differences in lipid digestion and metabolism which exist between breast fed and formula fed infants and which may significantly influence fatty acid bioavailability.

Recommendations are made for the lipid content and fatty acid composition of term infant formulas (especially for lauric, linoleic, α-linolenic, long chain 20 and 22C n-3 and n-6 polyunsaturated fatty acids and thetransfatty acids).

Further research is required to define more clearly the long term nutritional, growth and developmental effects of structured lipids in formulas for term infants. More information is required on the differential handling of LCPUFA and other fatty acids at the organ and cellular level. There is a need for large (multi-centre) randomized studies to determine the short and long term functional effects of LCPUFA supplementation. Further research and development is required to determine a commercial source of LCPUFA which is safe, effective and economic. Further information is required on the short and long term effects of cholesterol intake during infancy, and in particular its relationship to LCPUFA metabolism. Long term studies should be initiated to determine the relationship of infant diet (especially saturated fatty acid and cholesterol intake) to the development of cardiovascular disease.

Long-chain n-6 polyunsaturated fatty acids in breast milk decrease the risk of HIV transmission through breastfeeding

BACKGROUND

Breastfeeding accounts for a sizable proportion of infant HIV infections. Some fatty acids (FAs) are potent immunomodulators with virucidal activity, and their primary source in breastfed children is breast milk.

OBJECTIVES

The aims of the study were to examine whether the percentage weight concentration of FAs in breast milk was associated with the risk of mother-to-child transmission (MTCT) of HIV by breastfeeding and with shedding of cell-free virus (CFV) or cell-associated virus (CAV) in breast milk.

DESIGN

We conducted a case-control study nested within a cohort of HIV-infected Tanzanian women and children. We matched 59 incident breastfeeding MTCT cases to 59 nontransmitting controls based on the child's age at sample collection. We quantified FAs, CFV, and CAV in a breast milk sample collected before the infant's first positive HIV test.

RESULTS

After adjustment for indicators of maternal HIV disease stage, the risk of MTCT was inversely related to 11c,14c-eicosadienoic acid [odds ratio (OR) for quartile 4 compared with quartile 1: 0.21; P for trend = 0.04], arachidonic acid (OR: 0.21; P for trend = 0.03), and dihomo-gamma-linolenic acid (OR: 0.24; P for trend = 0.03); the latter 2 were also linearly, inversely related to virus shedding in breast milk. Lauric acid and pentadecanoic acid were associated with increased MTCT, whereas trans FAs were related to higher CAV and CFV.

CONCLUSION

Increasing concentrations of long-chain n-6 polyunsaturated FAs in breast milk might reduce the risk of MTCT.

Intake of milk fat, reflected in adipose tissue fatty acids and risk of myocardial infarction: a case–control study

OBJECTIVE

To study the association between content of fatty acids from milk fat (14:0, 15:0 and 17:0) in adipose tissue and risk of a first myocardial infarction (MI).

DESIGN AND SUBJECTS

A case-control study with 99 patients and 98 population controls both men and postmenopausal women, age 45-75 year. Adipose tissue fatty acids were determined by gas-liquid chromatography.

RESULTS

The content of 14:0, 14:1, 15:0, 17:0 and 17:1 were all significantly higher in adipose tissue of controls than of the patients. Age and sex adjusted odds ratios (OR) for MI were significantly reduced with increasing quartiles of 14:0, 14:1, 15:0 and 17:1 in adipose tissue, but except for 15:0 (OR = 0.36, 95% CI 0.13-0.99), the trend was no longer significant after further adjustment for waist-to-hip ratio, smoking and family history for coronary heart disease. Correlations between 14:0 and 15:0 in adipose tissue, and waist-to-hip ratio were significantly negative (r = -0.22 for both, P < 0.01).

CONCLUSION

Our study suggests that intake of dairy fat or some other component of dairy products, as reflected by C15:0 as marker in adipose tissue, may protect persons at increased risk from having a first MI, and that the causal effects may rely on other factors than serum cholesterol.

SPONSORSHIP

Throne Holst's foundation for Nutrition Research, Research Council of Norway, The Norwegian Association of Margarine Producers, DeNoFa Fabriker A/S, TINE BA.

Why does tumor-associated fatty acid synthase (oncogenic antigen-519) ignore dietary fatty acids?

The hyperactivation of fatty acid synthase (FAS)-catalyzed de novo biosynthesis of fatty acids is a molecular marker linked to tumor virulence in population studies of human malignancies. This activation appears to be linked to neoplastic transformation, since high levels of FAS have also been identified in pre-malignant lesions. This dependence of cancer upon accelerated lipogenesis differs from normal human tissues, in which FAS is suppressed by the presence of small amounts of fatty acids in the diet. The molecular mechanisms by which cancer cells constitutively exhibit FAS overexpression and hyperactivity have begun to emerge. The active involvement of the mitogen-activated protein kinase (MAPK) extracellular signal-regulated kinase (MAPK ERK1/2) and phosphatidylinositol-3'-kinase (PI-3'K)/protein kinase B (AKT) transduction cascades in the overexpression of FAS has been recently demonstrated in several cancer cell models. Strikingly, insulin-regulated stimulation of FAS expression in adipose cells is also mediated by the PI-3'K pathway with AKT being involved as a downstream effector. Moreover, FAS overexpression in tumor cells has been demonstrated to occur through a modification of the transcription factor sterol regulatory element-binding protein-1c (SREBP-1c), the major regulatory factor of FAS in liver and adipose tissues, which, in turn, is known to be regulated by MAPK ERK1/2 and PI-3'K/AKT pathways. Therefore, the signal transduction pathways regulating FAS expression in normal and cancer cells seem to share several downstream elements. However, the upstream mechanisms controlling FAS expression in cancer cells must be different from those in normal tissues, since tumor-associated FAS expression seems to be insensitive to nutritional signals. In pre-neoplastic lesions, we hypothesize that the early activation of FAS in pre-malignant cells represents a survival strategy which occurs to compensate for an insufficiency of both oxygen and dietary fatty acids due to, e.g., lack of angiogenesis. Thus, FAS activation reflects an epigenetic dysregulation of the lipogenic pathway in response to the microenvironment of tumors containing regions of poor oxygenation. Upon this unusual metabolic situation, FAS up-regulation also represent a metabolic strategy to maintain high proliferation rates of surviving cells in the absence of exogenous dietary fatty acids. Concomitantly, a variety of oncogenic changes (H-ras, erb B-2, etc.) may result in the constitutive activation of MAPK and PI-3'K/AKT signaling cascades, which, in turn, can activate SREBP-1c and, subsequently, tumor-associated FAS-catalyzed endogenous lipogenesis. Thereafter, high levels of FAS are maintained in coordination with increased demand for fatty acid metabolism and/or membrane synthesis in response to cancer-related overexpression of growth factors (e.g., EGF, heregulin) and/or growth factor receptors (e.g., EGFR, Her-2/neu). The aberrant MAPK and PI-3'K/AKT cascades driven by these oncogenic changes subvert the downregulatory effects of physiological concentrations of dietary fatty acids, resulting in a cancer-associated FAS insensitivity to nutritional signals. This model does not exclude that fundamental differences in the ability of FAS gene to respond to normal fatty acid's downregulatory actions may also synergistically interact with oncogenic signals to constitutively maintain an elevated FAS-dependent de novo endogenous fatty acid biogenesis in cancer cells in spite of high levels of circulating dietary fatty acids.

Influences of maternal dietary intake and suckling on breast milk lipid and fatty acid composition in low-income women from Brasilia, Brazil

Diet has a strong effect, while suckling stimulus is believed not to influence breast milk fatty acids. The effect of dietary pattern and suckling on the fatty acid composition of Brazilian women's breast milk was studied. A cross-sectional study was conducted with low-income women living in the central region of Brazil, where dietary DHA is not readily available. Fore and hind milk fatty acids were collected from 77 women on day 15+/-1 postpartum, and information on maternal characteristics and dietary habit was taken. The effect of suckling stimulus was measured by the changes between fore and hind milk. The mean body mass index (BMI) of volunteers was 23.7+/-3.2 kg/m(2), and the milk lipid concentration was 4.8+/-1.2 g/dl. A mixture of traditional and western type of dietary habit, high in fat and sugar was observed. The fatty acids of the subject's milk were 41.93+/-1.42% saturated, 33.31+/-1.67% monounsaturated and 25.03+/-5.23% polyunsaturated (wt/wt). The DHA level in the milk was 0.34+/-0.19%, similar to the values found in milk of many western societies. DHA and 18:3n-3 levels increased from fore to hind milk (p<0.05). Correlation existed mostly between dietary components and milk 16:0 and oleic acid (18:0). An analysis of classes of fatty acids in milk showed oleic acid (18:0) to present a negative correlation with all milk fatty acid classes. The results suggest that breast milk fatty acids of Brazilian women reflect a western maternal dietary pattern and are influenced by the suckling.

Lactational changes in the fatty acid composition of human milk gangliosides

The objectives of this work were to study the FA composition of milk gangliosides, as well as to gain further insight into the characterization of human milk gangliosides. The potential capacity of human milk gangliosides to adhere to human enterotoxigenic Escherichia coli (ETEC-strains) was also studied. Human milk gangliosides were isolated and identified by high-performance TLC or immunoassay. The latter also was used to assay bacterial adhesion. The FA composition of gangliosides was studied by GC. The presence of O-acetyl GD3 (Neu5,9Ac2alpha2-8 NeuAcalpha2-3Galbeta1-4GlcCer) and trace amounts of GM1 [Galgamma1]3-3GalNAcgamma1,-3(Neualpha2-3)Galbeta1-4GlcCerl in human milk was confirmed. Medium-chain FA were almost absent in colostrum, whereas in the subsequent stages they rose to 20%. The levels of long-chain FA decreased after colostrum. With respect to the degree of saturation, gangliosides from colostrum were richer in monounsaturated FA than gangliosides synthesized during the rest of the lactation period, opposite to the pattern for PUFA. A human-ETEC colonization factor antigen II-expressing strain showed binding capacity to human milk GM3 (NeuAcalpha2-3Gal[1-4GlcCer). New data on human milk gangliosides have been gathered. A thorough knowledge of their composition is needed since they may have important biological implications in regard to newborns' defense against infection.

Increased fatty acid synthase expression and activity during progression of prostate cancer in the TRAMP model

BACKGROUND

Fatty acid synthase (FAS) is the major enzyme required to convert carbohydrates to fatty acids. Recent evidence suggests that FAS activity is essential for prostate cancer growth and survival, since blocking the enzyme activity results in cell death. In this study, the role of FAS up-regulation during prostate tumor progression in the transgenic adenocarcinoma of mouse prostate (TRAMP) model was investigated. Sensitivity to FAS anti-metabolites was also analyzed in TRAMP prostate tumor cells and tissue to determine therapeutic potential of FAS inhibition in the treatment of prostate cancer.

METHODS

FAS expression was evaluated by immunohistochemistry of TRAMP tissues, including primary and metastatic lesions in mice of varying ages. FAS pathway activity was studied in vitro using TRAMP-derived cell lines and in vivo in TRAMP tissues. The sensitivity of TRAMP cell lines and tissues to the antimetabolite drugs (2R,3S)-2,3-epoxy-4-oxo-7,10-trans, transdodecadienamide (cerulenin) and C-75, which target FAS, was determined by FAS antimetabolite inhibition of 14C-acetate conversion to fatty acids, cell growth inhibition, and apoptosis analyses.

RESULTS

High FAS expression and activity in the TRAMP mouse prostate was evident at 12 weeks of age compared with nontransgenic littermates and further increased with age, tumor progression, and in metastatic lesions. FAS pathway inhibition resulted in a dose-dependent reduction in cell survival and decreased enzyme activity in these models.

CONCLUSIONS

These data suggest that the up-regulation of FAS expression play a role in tumorigenesis of the prostate in the TRAMP model and hence can provide valuable insight into human prostate cancer. Given the response of tumor cells to FAS antimetabolites, FAS may serve as a novel target for prostate cancer therapy.

Estimated biological variation of the mature human milk fatty acid composition

We estimated the biological variation (CV(biol)) of 28 fatty acids (FA) in 465 mature human milk samples from The Netherlands, Caribbean, Jerusalem, Tanzania and Pakistan, by using data from the observed variation (CV(obs)) and analytical variation (CV(anal)). CV(biol) of the various regions was remarkably similar. The average CV(biol) of 455 samples, Pakistan excluded, ranged from 12.7% for 16:0 and 18.9% for 18:1 omega 9 to 68% for 22:6 omega 3 and about 100% for 20:5 omega 3. Those of 20:4 omega 6, 18:2 omega 6 and 18:3 omega 3 were 28.0, 33.0 and 37.3%, respectively. Because of the large CV(biol) and the many dietary changes in recent history, it seems impossible to consider the present human milk FA composition as the 'gold standard' for infant formula. Optimal human milk FA composition should rather derive from populations that consume traditional diets or from the scientific data that show the function of the individual FAs in neonatal development.

Physiological aspects of human milk lipids

Human milk from healthy and well-nourished mothers is the preferred form of feeding for all healthy newborn infants. The nutrient supply with human milk supports normal growth and development of the infant. Here the general characteristics of human milk lipids and recent knowledge on lactational physiology, composition and functional aspects of human milk lipids are discussed. Lipids in human milk represent the main source of energy for the breastfed baby and supply essential nutrients such as fat-soluble vitamins and polyunsaturated fatty acids (PUFA). The essential fatty acids linoleic and alpha-linolenic acids (LA and ALA) are precursors of long-chain polyunsaturated fatty acids (LC-PUFA), including arachidonic (20:4n-6) and docosahexaenoic (22:6n-3) acids (AA and DHA). LC-PUFA serve as indispensable structural components of cellular membranes and are deposited to a considerable extent in the growing brain and the retina during perinatal development. The supply of preformed LC-PUFA with human milk lipids has been related to functional outcomes of the recipient infants such as visual acuity and development of cognitive functions during the first year of life. Recent stable isotope studies indicate that the major portion of milk PUFA is not derived directly from the maternal diet, but stems from endogenous body stores. Thus, not only the woman's current but also her long-term dietary intake is of marked relevance for milk fat composition.

Immunohistochemical expression of human erythrocyte glucose transporter and fatty acid synthase in infiltrating breast carcinomas and adjacent typical/atypical hyperplastic or normal breast tissue

To evaluate the immunohistochemical expression of GLUT1, human erythrocyte glucose transporter 1, and fatty acid synthase (FAS), 66 human breast carcinomas and adjacent peritumoral tissue were studied. GLUT1 and FAS were expressed in 53 and 61 carcinomas, in 17 and 14 typical/atypical hyperplastic tissues, and in 16 and 13 tissues adjacent to tumor normal breast tissue, respectively. Statistical analysis revealed association between invasive carcinomas, invasive carcinomas with in situ component and GLUT1 immunostaining. GLUT1 staining was associated with tumor grade, FAS with tumor stage, and GLUT1 and FAS coexpression with tumor grade. Controls expressed no immunostaining. GLUT1 and FAS are new markers involved in the biologic activities of cancer cells. GLUT1 and FAS coexpression may indicate increased use of energy by the neoplastic cells correlated with poorly differentiated features and aggressive behavior. The innovative finding that GLUT1 and FAS are observed in mammary carcinoma adjacent nonneoplastic tissues may suggest a role in detecting initial phases of breast carcinogenesis.

Increased fatty acid synthase as a therapeutic target in androgen-independent prostate cancer progression

BACKGROUND

Fatty acid synthase (FAS) performs the anabolic conversion of dietary carbohydrate or protein to fat. FAS expression is low in most normal tissues, but is elevated in many human cancers, including androgen-sensitive and androgen-independent prostate cancer.

METHODS

Immunohistochemical evaluation of FAS expression was performed in human prostate cancer specimens under various states of androgen ablation. In vitro and in vivo prostate cancer models were evaluated for FAS expression and activity under androgenic and androgen-depleted conditions, and were tested for sensitivity to antimetabolite drugs that target fatty acid synthesis.

RESULTS

While FAS expression in the prostate was androgen responsive, it persisted or was reactivated in human prostate carcinoma after androgen ablation, and was high in 82% of lethal tumors examined at autopsy. Similar patterns of FAS expression and fatty acid synthesis were seen in cell culture and xenograft models of human prostate cancer. Pharmacologic inhibition of FAS resulted in a dose-dependent reduction of tumor growth in these models, including fourfold inhibition of an androgen-independent human prostate cancer xenograft with little associated toxicity.

CONCLUSIONS

The data suggest that FAS expression/FA synthesis provides an important functional aspect of the malignant phenotype in prostate cancer, perhaps supporting cell growth or survival. FAS expression may be upregulated by alternate signaling pathways important for prostate cancer growth under androgen withdrawal. The re-emergence of FAS expression and activity during the development of androgen independence demonstrate that FAS may serve as a novel target for antimetabolite therapy in prostate cancer.

Sterol regulatory element-binding protein-1 participates in the regulation of fatty acid synthase expression in colorectal neoplasia

Endogenous fatty acid synthesis has been observed in certain rapidly proliferating normal and neoplastic tissues. Sterol regulatory element-binding proteins (SREBPs) are transcription factors that regulate the expression of lipogenic genes including fatty acid synthase (FAS), the major biosynthetic enzyme for fatty acid synthesis. We have previously shown that SREBP-1, FAS, and Ki-67, a proliferation marker, colocalized in the crypts of the fetal gastrointestinal tract epithelium. This study sought to determine whether SREBP-1 participates in the regulation of proliferation-associated fatty acid synthesis in colorectal neoplasia. An immunohistochemical analysis of SREBP-1, FAS, and Ki-67 expression in 25 primary human colorectal carcinoma specimens showed colocalization in 22 of these. To elucidate a functional linkage between SREBP-1 activation and proliferation-associated FA synthesis, SREBP-1 and FAS content were assayed during the adaptive response of cultured HCT116 colon carcinoma cells to pharmacological inhibition of FA synthesis. Cerulenin and TOFA each inhibited the endogenous synthesis of fatty acids in a dose-dependent manner and each induced increases in both precursor and mature forms of SREBP-1. Subsequently, both the transcriptional activity of the FAS promoter in a luciferase reporter gene construct and the FAS expression increased. These results demonstrate that tumor cells recognize and respond to a deficiency in endogenous fatty acid synthesis by upregulating both SREBP-1 and FAS expression and support the model that SREBP-1 participates in the transcriptional regulation of lipogenic genes in colorectal neoplasia.

Correlation between the content of intermediate chain-length fatty acids and copper in the milk of Fulani women

Intermediate chain-length fatty acids (C10-C14) in human milk triglycerides provide an easily absorbable fuel that provide a significant amount of the energy needed for growth during the first few months of life. The C10-C14 fatty acid and trace mineral content of human milk is variable. In this report we examined the relationship between the content of calcium, copper, magnesium, manganese, phosphorus, and zinc, and the weight percentage of C10-C14 fatty acids in milk from 33 Fulani women in northern Nigeria between 2 and 24 weeks post-gestation. The milk from these women contained proportions of C10-C14 fatty acids that were comparable to those reported for other populations around the world, as were the concentrations of Ca, Cu, Mg, Mn, Zn and P. Significant correlations were observed between the milk content of Cu and the wt% of C10 (P=0. 005, r=0.475), C12 (P=0.001, r=0.539), C14 (P=0.44, r=0.352) and the total intermediate chain-length fatty acids (P=0.008, r=0.450). No correlations were observed between these fatty acids and any of the other five minerals. We speculate that the relationship between Cu and fatty acids could be related to a requirement for Cu by an enzyme required for C10-C14 fatty acid biosynthesis (e.g. decanoyl deacylase) in mammary tissue, or to some unique Cu binding properties of the intermediate chain length fatty acids.

Synthesis and antitumor activity of an inhibitor of fatty acid synthase

Compared to normal human tissues, many common human cancers, including carcinoma of the colon, prostate, ovary, breast, and endometrium, express high levels of fatty acid synthase (FAS, EC ), the primary enzyme responsible for the synthesis of fatty acids. This differential expression of FAS between normal tissues and cancer has led to the notion that FAS is a target for anticancer drug development. Recent studies with C75, an inhibitor of fatty acid synthesis, have shown significant antitumor activity with concomitant inhibition of fatty acid synthesis in tumor tissue and normal liver. Importantly, histopathological analysis of normal tissues after C75 treatment showed no adverse effects on proliferating cellular compartments, such as bone marrow, gastrointestinal tract, skin, or lymphoid tissues. In this study, we describe the de novo synthesis of C75 based on the known mechanism of action of cerulenin and the theoretical reaction intermediates of the beta-ketoacyl synthase moiety of FAS. In addition, we demonstrate that C75 is a synthetic, chemically stable inhibitor of FAS. C75 inhibits purified mammalian FAS with characteristics of a slow-binding inhibitor and also inhibits fatty acid synthesis in human cancer cells. Treatment of human breast cancer cells with [5-(3)H]C75 demonstrates that C75 reacts preferentially with FAS in whole cells. Therefore, we have shown that the primary mechanism of the antitumor activity of C75 is likely mediated through its interaction with, and inhibition of, FAS. This development will enable the in vivo study of FAS inhibition in human cancer and other metabolic diseases.

Synthesis and antitumor activity of an inhibitor of fatty acid synthase

Compared to normal human tissues, many common human cancers, including carcinoma of the colon, prostate, ovary, breast, and endometrium, express high levels of fatty acid synthase (FAS, EC ), the primary enzyme responsible for the synthesis of fatty acids. This differential expression of FAS between normal tissues and cancer has led to the notion that FAS is a target for anticancer drug development. Recent studies with C75, an inhibitor of fatty acid synthesis, have shown significant antitumor activity with concomitant inhibition of fatty acid synthesis in tumor tissue and normal liver. Importantly, histopathological analysis of normal tissues after C75 treatment showed no adverse effects on proliferating cellular compartments, such as bone marrow, gastrointestinal tract, skin, or lymphoid tissues. In this study, we describe the de novo synthesis of C75 based on the known mechanism of action of cerulenin and the theoretical reaction intermediates of the beta-ketoacyl synthase moiety of FAS. In addition, we demonstrate that C75 is a synthetic, chemically stable inhibitor of FAS. C75 inhibits purified mammalian FAS with characteristics of a slow-binding inhibitor and also inhibits fatty acid synthesis in human cancer cells. Treatment of human breast cancer cells with [5-(3)H]C75 demonstrates that C75 reacts preferentially with FAS in whole cells. Therefore, we have shown that the primary mechanism of the antitumor activity of C75 is likely mediated through its interaction with, and inhibition of, FAS. This development will enable the in vivo study of FAS inhibition in human cancer and other metabolic diseases.

The fatty acid composition of human milk in northern Nigeria

The authors previously reported that the milk of Yoruba women in southwestern Nigeria was deficient in alpha-linolenic acid and contained a high percentage (42%) of medium chain-length fatty acids (MCFA, C10-C14). In the present study, the authors used capillary gas-liquid chromatography to analyze the milk of Hausa women in the northern region of Nigeria. The milk of the Hausa women contained 27% MCFA, 10.6% linoleic acid, 0.41% alpha-linolenic acid, 0.52% arachidonic acid, and 0.32% docosahexaenoic acid. The proportion of alpha-linolenic acid in the serum phospholipids of a subset of exclusively breastfed infants (n = 15; mean age, 6.2 +/- 0.3 months) was below the limit of detection (< 0.03%). While the milk of women in northern Nigeria is adequate with regard to n-3 and n-6 fatty acids, to satisfy the requirements for alpha-linolenic acid, it may be necessary to supplement the infants of these women after the first 6 months of life.

Effect of docosahexaenoic acid supplementation of lactating women on the fatty acid composition of breast milk lipids and maternal and infant plasma phospholipids

To determine whether docosahexaenoic acid (DHA) supplementation of breast-feeding mothers increases the DHA contents of breast milk and infant plasma phospholipids (PPs), breast-feeding women were randomly assigned to 3 DHA-supplementation groups (170-260 mg/d) or a control group. Group 1 (n = 6) consumed an algae-produced high-DHA triacylglycerol; group 2 (n = 6) consumed high-DHA eggs; group 3 (n = 6) consumed a high-DHA, low-eicosapentaenoic acid marine oil; and group 4 (n = 6) received no supplementation. From before to after supplementation (2 and 8 wk postpartum), mean (+/-SD) maternal PP DHA increased in groups 1, 2, and 3 by 1.20 +/- 0.53, 0.63 +/- 0.82, and 0.76 +/- 0.35 mol% of fatty acids, respectively (23-41%), but decreased in group 4 by 0.44 +/- 0.34 mol% (15%). Breast-milk DHA of groups 1, 2, and 3 increased by 0.21 +/- 0.16, 0.07 +/- 0.11, and 0. 12 +/- 0.07 mol%, respectively (32-91%) but decreased in group 4 by 0.03 +/- 0.04 mol% (17%). Mean infant PP DHA in groups 1, 2, and 3 increased by 1.63 +/- 0.79, 0.40 +/- 1.0, and 0.98 +/- 0.61 mol%, respectively (11-42%), but only by 0.18 +/- 0.74 mol% (5%) in group 4. Correlations between the DHA contents of maternal plasma and breast milk and of milk and infant PPs were significant. Breast-milk and maternal and infant PP 22:5n-6 concentrations were lowest in group 2. DHA supplementation increases the plasma and breast-milk DHA concentrations of lactating women, resulting in higher PP DHA concentrations in infants.

Immunohistochemical study of fatty acid synthase, Ki67, proliferating cell nuclear antigen, and p53 expression in hyperplastic parathyroids

Patients with secondary hyperparathyroidism following chronic renal disease frequently develop hyperplastic parathyroids. Hyperplastic parathyroids have an increased number of chief cells, a decreased amount of stromal fat, and a nodular or diffuse histologic pattern. Hyperplastic parathyroids may also express higher proliferative activity compared with controls. We evaluated the morphologic features and immunohistochemical expression of fatty acid synthase (FAS), Ki67, proliferating cell nuclear antigen, and p53 protein in 78 hyperplastic parathyroids from 20 patients with secondary hyperparathyroidism. Twenty normal parathyroids incidentally removed during nonneoplastic thyroid surgery were used as controls. Our results showed that hyperplastic glands overexpress FAS (P =.06). Statistical analysis also revealed a significant association between FAS and p53 protein (P =.006) and between FAS and hyperplastic glands with a predominant nodular pattern (P =.02). Hyperplastic parathyroids from patients with chronic renal failure strongly express FAS. Fatty acid synthase may therefore be a potential biological indicator of highly proliferating parathyroid cells.

Interrelation among dietary energy and fat intakes, maternal body fatness, and milk total lipid in humans

The relationship between maternal dietary intakes of energy or fat maternal body composition and the milk fat concentration is an important element in understanding the role of breast-milk in infant nutrition. In most studies in both developing and developed countries, no relation between maternal energy intake and milk fat content was observed. In only one published study, in which maternal fat intake comprised a very low 5% of calories, was a short term reduction in milk lipid observed in some subjects. On the other hand, a positive relation between maternal fatness and milk fat is evident in both well-nourished and under-nourished women when appropriate methodologies have been used. Low milk fat concentrations are associated with higher milk volumes probably because infant demand determines milk intake, compensating, at least partially, for low milk fat. No impairment of infant growth was associated with low milk fat, in studies where it has been measured. The mechanism for the relationship between body fat and milk fat is a fertile field for additional investigation.

Lipid and lipoprotein analysis of cats with lipoprotein lipase deficiency

BACKGROUND

We have previously described a colony of domestic cats with a naturally occurring mutation in the lipoprotein lipase (LPL) gene. We have now further characterized cats homozygous for LPL deficiency (LPL -/-, homozygotes), and have contrasted these with heterozygotes (LPL +/-) and normal cats (LPL +/+).

MATERIALS AND METHODS

Density gradient ultracentrifugation with subsequent lipid analysis, agarose and polyacrylamide gel electrophoresis was used to examine detailed liproprotein differences between the genotypes. Oral fat loading studies and breast milk fatty acid analysis were also performed to further characterize the phenotypic expression of LPL deficiency in this model system.

RESULTS

Several lipid abnormalities associated with homozygosity for LPL deficiency were evident. Triglyceride-rich lipoprotein-triglycerides (TRL-TG) and cholesterol (TRL-C) were higher (TRL-TG 2.09 +/- 1.14 vs. 0.15 +/- 0.04 mmol L-1, P < 0.001; TRL-C 0.42 +/- 0.30 vs. 0.11 +/- 0.16 mmol L-1, P < 0.05) in male -/- than in male +/+ cats, as was HDL-cholesterol (HDL-C, 1.75 +/- 0.24 vs. 1.41 +/- 0.14 mmol L-1, P < 0.05). LDL-C levels were lower in homozygous cats than in control cats, similar to what is seen in human LPL deficiency. Oral fat loading studies revealed that homozygous cats have a marked reduced ability to clear plasma TGs in terms of peak time (7 h vs. 3 h), peak height (9.36 vs. 1.1 mmol L-1), area under the TG clearance curve (AUC, 280.3 vs. 2.2 h mmol L-1) and time to return to baseline. Fasting lipid and lipoprotein levels were not significantly different between heterozygous and normal cats. However, oral fat loading in heterozygotes revealed an intermediate phenotype (peak of 2.35 mmol L-1 at 5 h, AUC 13.1 h mmol L-1), highlighting the impaired TG clearance in these animals.

CONCLUSION

Thus, LPL deficiency in the cat results in a lipid and lipoprotein phenotype that predominantly parallels human LPL deficiency, further validating the use of these animals in studies on the pathobiology of LPL.

A semiautomated enzymatic method for determination of nonesterified fatty acid concentration in milk and plasma

An enzymatic assay for the determination of nonesterified fatty acid concentrations in milk and plasma is described. The procedure is semiautomated for use with a plate luminometer or plate spectrophotometer and enables routine batch processing of large numbers of small samples (< or =5 microL). Following the activation of nonesterified fatty acids (NEFA) by acylCoA synthetase, the current assay utilizes UDP-glucose pyrophosphorylase to link inorganic pyrophosphate to the production of NADH through the reactions catalyzed by phosphoglucomutase and glucose-6-phosphate 1-dehydrogenase. With this assay sequence the formation of NADH from NEFA is complete within 50 min at 37 degrees C. Enzymatic spectrophotometric techniques were unsuitable for NEFA determination in human milk due to the opacity of the sample. The use of the NADH-luciferase system has overcome this problem, allowing the enzymatic determination of NEFA in human milk. Sample collection and treatment procedures for milk and plasma have been developed to prevent enzymatic lipolysis and to limit interference from enzymes present in milk. The recovery of palmitic acid added to milk and plasma samples was 94.9+/-2.9 and 100+/-4.5%, respectively. There was no difference (P = 0.13) in plasma NEFA concentrations determined by the current method and a commercially available enzymatic spectrophotometric technique (Wako NEFA-C kit). Plasma NEFA concentrations determined by gas chromatography were 28% higher compared to both the Wako NEFA-C kit and the current method.

Three variants of parathyroid hormone-related protein messenger RNA are expressed in human mammary gland

PTH-related protein (PTHrP) is found in a variety of tissues; particularly high levels are present in human milk. The structure of the human PTHrP gene is complex, and alternative splicing allows expression of three different variants PTHrP139, PTHrP173, and PTHrP141, respectively. To determine which of the variants are expressed in human mammary gland a reverse transcriptase polymerase chain reaction (RT-PCR) method was elaborated, distinguishing the three variants. mRNA isolated from human milk cells, human mammary epithelial cells (HMEC) and human nonlactating mammary gland cells were analyzed. The RT-PCR experiments resulted in amplification of DNA fragments corresponding to all three variants for all three cell sources tested. The nucleotide sequences of the PCR fragments were determined and verified to be identical to the reported sequences. Hence, it is concluded that human mammary gland epithelial cells express three variants of PTHrP. Whether these have different physiologic effects in the mammary gland or in the breast fed infant remain to be explored.