Fatty acid proportions in cholesterol esters and risk of premature death from cancer in middle aged French men

Unveiling the MUFA-Cancer Connection: Insights from Endogenous and Exogenous Perspectives

Monounsaturated fatty acids (MUFAs) have been the subject of extensive research in the field of cancer due to their potential role in its prevention and treatment. MUFAs can be consumed through the diet or endogenously biosynthesized. Stearoyl-CoA desaturases (SCDs) are key enzymes involved in the endogenous synthesis of MUFAs, and their expression and activity have been found to be increased in various types of cancer. In addition, diets rich in MUFAs have been associated with cancer risk in epidemiological studies for certain types of carcinomas. This review provides an overview of the state-of-the-art literature on the associations between MUFA metabolism and cancer development and progression from human, animal, and cellular studies. We discuss the impact of MUFAs on cancer development, including their effects on cancer cell growth, migration, survival, and cell signaling pathways, to provide new insights on the role of MUFAs in cancer biology.

Dietary intake and biomarkers of linoleic acid and mortality: systematic review and meta-analysis of prospective cohort studies

BACKGROUND

Current evidence on associations between intakes of linoleic acid (LA), the predominant n-6 (ω-6) fatty acid, and mortality is inconsistent and has not been summarized by a systematic review and meta-analysis.

OBJECTIVE

The aim was to perform a systematic review and meta-analysis of prospective cohort studies to examine associations between LA intake and mortality.

METHODS

We conducted a comprehensive search of MEDLINE and EMBASE databases through 31 July 2019 for prospective cohort studies reporting associations of LA (assessed by dietary surveys and/or LA concentrations in adipose tissue or blood compartments) with mortality from all causes, cardiovascular disease (CVD), and cancer. Multivariable-adjusted RRs were pooled using random-effects meta-analysis.

RESULTS

Thirty-eight studies reporting 44 prospective cohorts were identified; these included 811,069 participants with dietary intake assessment (170,076 all-cause, 50,786 CVD, and 59,684 cancer deaths) and 65,411 participants with biomarker measurements (9758 all-cause, 6492 CVD, and 1719 cancer deaths). Pooled RRs comparing extreme categories of dietary LA intake (high vs low) were 0.87 (95% CI: 0.81, 0.94; I2 = 67.9%) for total mortality, 0.87 (95% CI: 0.82, 0.92; I2 = 3.7%) for CVD mortality, and 0.89 (95% CI: 0.85, 0.93; I2 = 0%) for cancer mortality. Pooled RRs for each SD increment in LA concentrations in adipose tissue/blood compartments were 0.91 (95% CI: 0.87, 0.95; I2 = 64.1%) for total mortality, 0.89 (95% CI: 0.85, 0.94; I2 = 28.9%) for CVD mortality, and 0.91 (95% CI: 0.84, 0.98; I2 = 26.3%) for cancer mortality. Meta-regressions suggested baseline age and dietary assessment methods as potential sources of heterogeneity for the association between LA and total mortality.

CONCLUSIONS

In prospective cohort studies, higher LA intake, assessed by dietary surveys or biomarkers, was associated with a modestly lower risk of mortality from all causes, CVD, and cancer. These data support the potential long-term benefits of PUFA intake in lowering the risk of CVD and premature death.

Inhibition of stearoyl CoA desaturase-1 activity suppresses tumour progression and improves prognosis in human bladder cancer

Urinary bladder neoplasm is one of the most common cancers worldwide. Cancer stem cells (CSCs) have been proven to be an important cause of cancer progression and poor prognosis. In the present study, we established bladder CSCs and identified the crucial differentially expressed genes (DEGs) between these cells and parental bladder cancer cells. Analyses of bioinformatics data and clinical samples from local hospitals showed that stearoyl CoA desaturase‐1 (SCD) was the key factor among the DEGs. A significant correlation between SCD gene expression and poor prognosis among patients with bladder cancer was observed in our data. Loss‐of‐function experiments further revealed that the SCD inhibitor A939572 and SCD gene interference reduced cell proliferation and invasion. The above data suggest that SCD may serve as a novel marker for the prediction of tumour progression and poor prognosis in patients with bladder cancer.

Stearoyl CoA desaturase-1: New insights into a central regulator of cancer metabolism

The processes of cell proliferation, cell death and differentiation involve an intricate array of biochemical and morphological changes that require a finely tuned modulation of metabolic pathways, chiefly among them is fatty acid metabolism. The critical participation of stearoyl CoA desaturase-1 (SCD1), the fatty acyl Δ9-desaturing enzyme that converts saturated fatty acids (SFA) into monounsaturated fatty acids (MUFA), in the mechanisms of replication and survival of mammalian cells, as well as their implication in the biological alterations of cancer have been actively investigated in recent years. This review examines the growing body of evidence that argues for a role of SCD1 as a central regulator of the complex synchronization of metabolic and signaling events that control cellular metabolism, cell cycle progression, survival, differentiation and transformation to cancer.

A Promising Raman Spectroscopy Technique for the Investigation of trans and cis Cholesteryl Ester Isomers in Biological Samples

Lipid geometry is an important issue in biology and medicine. The cis-trans geometry conversion of double bonds in lipids is an endogenous process that can be mediated by sulfur-centered free radicals. Trans isomers of polyunsaturated fatty acids can be used as biological markers of free radical stress, and their presence in biological samples can be determined by synthesis and characterization of appropriate reference compounds. Fractions of plasma lipids, such as cholesteryl linoleate and arachidonate esters, are interesting targets because of their connection with membrane phospholipid turnover and their roles in cardiovascular health. In this context, Raman spectroscopy can provide a useful contribution, since Raman analysis can be performed directly on the lipid extracts without any derivatization reaction, is nondestructive, and can rapidly supply biochemical information. This study focused on the build up of Raman spectral libraries of different cis and trans isomers of cholesteryl esters to be used as references for the examination of complex biological samples and to facilitate isomer recognition. Unsaturated cholesteryl esters obtained by chemical synthesis and with different alkyl chain lengths, double bond numbers, or both, were analyzed. The potential of Raman analysis for trans isomer detection in biological samples was successfully tested on some cholesteryl ester lipid fractions from human serum. The data suggest promising applications of Raman spectroscopy in metabolomics and lipidomics.

Lipogenesis in cancer progression (review)

In normal tissues, energy-providing lipids come principally from circulating lipids. However, in growing tumors, energy supply is mainly provided by lipids coming from de novo synthesis. It is not surprising to see elevated expression of several lipogenic genes in tumors from different origins. The role of lipogenic genes in the establishment of the primary tumor has been clearly established. A large number of studies demonstrate a role of fatty acid synthase in the activation of cell cycle and inhibition of apoptosis in tumor cells. Other lipogenic genes such as the acetyl CoA carboxylase (ACC) and the stearoyl CoA desaturase 1 (SCD1) are highly expressed in primary tumors and also appear to play a role in their development. However, the role of lipogenesis in the metastatic process is less clear. In the present review, we aim to present the most recent evidences for the key role of lipogenic enzymes in the metastatic process and in epithelial to mesenchymal transition.

Cancer death is related to high palmitoleic acid in serum and to polymorphisms in the SCD-1 gene in healthy Swedish men

BACKGROUND

A high proportion of monounsaturated fatty acids (MUFAs) or a high ratio of MUFAs to saturated fatty acids in plasma, reflecting a high activity of the lipogenic enzyme stearoyl-CoA desaturase-1 (SCD-1), has been shown to be related to cancer death and incidence in some studies.

OBJECTIVES

The objective was to study whether the serum cholesteryl ester proportion of palmitoleic acid [16:1n-7 (16:1ω-3)] and the ratio of palmitoleic to palmitic acid (16:1n-7/16:0), as an estimation of the activity of SCD-1, are related to cancer death and to investigate whether polymorphisms in the SCD-1 gene are related to cancer mortality.

DESIGN

A community-based cohort of 50-y-old men was followed for a maximum of >40 y. Survival analysis was used to relate fatty acid composition in serum, analyzed at baseline by gas-liquid chromatography (n = 1981), and single nucleotide polymorphisms in the SCD-1 gene (n = 986) to cancer death. A 7-d dietary record was completed at age 70 y (n = 880).

RESULTS

The proportions of 16:1n-7 and the ratio of 16:1n-7 to 16:0 were associated with cancer mortality during follow-up in a comparison of the highest with the lowest quartile of 16:1n-7 (adjusted HR: 1.37; 95% CI: 1.04, 1.82). Inherited variance of the SCD-1 gene seemed to be related to cancer death, especially among men with a low proportion of PUFA in the diet in a comparison of the highest with the lowest weighted genetic risk score (HR: 2.14; 95% CI: 1.13, 4.04).

CONCLUSION

The findings are compatible with the hypothesis that there is an association between endogenously synthesized MUFAs and cancer death.

Decreasing stearoyl-CoA desaturase-1 expression inhibits β-catenin signaling in breast cancer cells

Stearoyl-CoA desaturase-1 (SCD1) is an endoplasmic reticulum anchored enzyme catalyzing the synthesis of monounsaturated fatty acids, mainly palmytoleyl-CoA and oleyl-CoA. Recent studies have revealed a function for SCD1 in the modulation of signaling processes related to cell proliferation, survival and transformation to cancer. We used MCF7 and MDA-MB-231 cells to analyze the role of SCD1 in the metastatic acquisition of breast cancer cells. Silencing SCD1 expression in breast cancer cells has no effect on cell viability but the levels of cell proliferation, cell cycle genes' expressions and the phosphorylation state of ERK1/2 MAPK are significantly reduced. Decreasing SCD1 expression also reduces the level of GSK3 phosphorylation, indicating higher activity of the kinase. Using cells fractionation, immunofluorescence and a β-catenin/TCF-responsive reporter construct, we demonstrate that lowering SCD1 expression leads to a decrease of β-catenin amounts within the nucleus and to inhibition of its transactivation capacity. Moreover, MDA-MB-231 cells transfected with the SCD1 siRNA show a lower invasive potential than the control cells. Taken together, our data demonstrate that low SCD1 expression is associated with a decrease in the proliferation rate of breast cancer cells associated with a decrease in ERK1/2 activation. SCD1 silencing also inhibits GSK3 phosphorylation, lowering β-catenin translocation to the nucleus, and, subsequently, its transactivation capacity and the expression of its target genes. Finally, we show that silencing SCD1 impairs the epithelial to mesenchymal transition-like behavior of the cells, a characteristic of metastatic breast cancer.

Roles of StearoylCoA Desaturase-1 in the Regulation of Cancer Cell Growth, Survival and Tumorigenesis

The development and maintenance of defining features of cancer, such as unremitting cell proliferation, evasion of programmed cell death, and the capacity for colonizing local tissues and distant organs, demand a massive production of structural, signaling and energy-storing lipid biomolecules of appropriate fatty acid composition. Due to constitutive activation of fatty acid biosynthesis, cancer cell lipids are enriched with saturated (SFA) and, in particular, monounsaturated fatty acids (MUFA), which are generated by StearoylCoA desaturase-1, the main enzyme that transforms SFA into MUFA. An increasing number of experimental and epidemiological studies suggest that high levels of SCD1 activity is a major factor in establishing the biochemical and metabolic perturbations that favors the oncogenic process. This review examines evidence that suggests the critical implication of SCD1 in the modulation of multiple biological mechanisms, specifically lipid biosynthesis and proliferation and survival signaling pathways that contribute to the development and progression of cancer.

Stearoyl-CoA desaturase-1: a novel key player in the mechanisms of cell proliferation, programmed cell death and transformation to cancer

As part of a shift toward macromolecule production to support continuous cell proliferation, cancer cells coordinate the activation of lipid biosynthesis and the signaling networks that stimulate this process. A ubiquitous metabolic event in cancer is the constitutive activation of the fatty acid biosynthetic pathway, which produces saturated fatty acids (SFAs) and monounsaturated fatty acids (MUFAs) to sustain the increasing demand of new membrane phospholipids with appropriate acyl composition. In cancer cells, the tandem activation of the fatty acid biosynthetic enzymes adenosine triphosphate citrate lyase, acetyl-CoA carboxylase (ACC) and fatty acid synthase (FAS) leads to increased synthesis of SFA and their further conversion into MUFA by stearoyl-CoA desaturase (SCD) 1. The roles of adenosine triphosphate citrate lyase, ACC and FAS in the pathogenesis of cancer have been a subject of extensive investigation. However, despite early experimental and epidemiological observations reporting elevated levels of MUFA in cancer cells and tissues, the involvement of SCD1 in the mechanisms of carcinogenesis remains surprisingly understudied. Over the past few years, a more detailed picture of the functional relevance of SCD1 in cell proliferation, survival and transformation to cancer has begun to emerge. The present review addresses the mounting evidence that argues for a key role of SCD1 in the coordination of the intertwined pathways of lipid biosynthesis, energy sensing and the transduction signals that influence mitogenesis and tumorigenesis, as well as the potential value of this enzyme as a target for novel pharmacological approaches in cancer interventions.

Coronary heart disease aetiology: associations and causality

Coronary heart disease (CHD) prevention has largely benefited in the past from the development of epidemiological research. However, the opposition association-causation is currently raised from observational data. We successively review, from some important examples, the classical methodological approach for discussing causality in epidemiology. The easy identification of DNA polymorphisms has prompted new CHD aetiological research in the past 10 years. Causality of the associations presents some special characteristics when genes are involved: necessity of replication, Mendelian randomization..., which might prove to be important in future research.

Zinc, copper, and magnesium and risks for all-cause, cancer, and cardiovascular mortality

BACKGROUND

Experimental data suggest that zinc, copper, and magnesium are involved in carcinogenesis and atherogenesis. Few longitudinal studies have related these minerals to cancer or cardiovascular disease mortality in a population.

METHODS

Data from the Paris Prospective Study 2, a cohort of 4035 men age 30-60 years at baseline, were used to assess the association between serum zinc, copper, and magnesium and all-cause, cancer, and cardiovascular disease mortality. Serum mineral values measured at baseline were divided into quartiles and classified into low (1st quartile, referent group), medium (2nd-3rd quartiles), and high (4th quartile) values. During 18-year follow up, 339 deaths occurred, 176 as a result of cancer and 56 of cardiovascular origin. Relative risks (RRs) for each element were inferred using Cox's proportional hazard model after controlling for various potential confounders.

RESULTS

High copper values (4th quartile) were associated with a 50% increase in RRs for all-cause deaths (RR = 1.5; 95% confidence interval = 1.1-2.1), a 40% increase for cancer mortality (1.4; 0.9-2.2), and a 30% increase for cardiovascular mortality (1.3; 0.6-2.8) compared with low values (1st quartile). High magnesium values were negatively related to mortality with a 40% decrease in RR for all-cause (0.6; 0.4-0.8) and cardiovascular deaths (0.6; 0.2-1.2) and by 50% for cancer deaths (0.5; 0.3-0.8). Additionally, subjects with a combination of low zinc and high copper values had synergistically increased all-cause (2.6; 1.4-5.0) and cancer (2.7; 1.0-7.3) mortality risks. Similarly, combined low zinc and high magnesium values were associated with decreased all-cause (0.2; 0.1-0.5) and cancer (0.2; 0.1-0.8) mortality risks.

CONCLUSIONS

High serum copper, low serum magnesium, and concomitance of low serum zinc with high serum copper or low serum magnesium contribute to an increased mortality risk in middle-aged men.

Lung cancer among women in France

As the incidence of primary lung cancer in women seems to be increasing in parallel with that of smoking, we conducted an exhaustive epidemiological study in 137 hospitals in 2000. We identified 904 women with proven primary lung cancer (mean age 63.9 years), many of whom have never smoked (32.3%), particularly in cases of adenocarcinoma (43.4%). Small cell cancer accounted for 16.1% of cases. Adenocarcinomas were the most frequent (45.3%) of the non-small cell lung cancer (NSCLC), followed by squamous cell (23.4%), large cell (11.6%) and bronchoalveolar (1.9%) carcinomas. About one third (32.2%) of NSCLC were stage III and 48.1% were stage IV. Over half of all adenocarcinomas were stage IV. According to multivariate analysis, adenocarcinoma is related to less smoking and younger age. In conclusion, many women affected by lung cancer have never smoked. Adenocarcinoma appears to be the most frequent form and more often at a metastatic stage.

Serum linoleic and total polyunsaturated fatty acids in relation to prostate and other cancers: a population-based cohort study

Dietary and serum fatty acid composition has been implicated in the pathogenesis of prostate and other cancers, but findings have been conflicting. Cohort studies reporting serum fatty acid composition are lacking. We assessed the association of fatty acid composition determined from dietary records and serum with incident cancer of the prostate and any site in a population-based cohort of 2,002 middle-aged Finnish men who were free of cancer at baseline and during the first 4 years of follow-up. During 12.6 years of follow-up, 46 men developed prostate cancer and 151 any cancer. Men with proportions of serum nonesterified [risk ratio (RR) 0.28; 95% confidence intervals (CI) 0.12-0.66] and esterified linoleic acid (RR 0.37; 95% CI = 0.16-0.86) and total polyunsaturated fatty acids (RR 0.30; 95% CI = 0.12-0.71) in the upper third were less than 1/3 as likely to develop prostate cancer during follow-up. Adjustment for possible confounders like socioeconomic status, physical activity, obesity and insulin concentrations did not attenuate the association. Similar but weaker associations with any cancer were found. Dietary linoleic acid intake also tended to be inversely associated with incident prostate cancer (age-adjusted RR for the upper vs. lower third 0.55; 95% CI = 0.26-1.14, p for the trend 0.097). Substitution of linoleic acid for saturated fat in middle-aged men consuming a high saturated-fat diet may decrease the risk of prostate and other cancers, although it is possible that some of the effect may be mediated by nutrients closely associated with vegetable fats.

Eicosapentaenoic acid and arachidonic acid: collaboration and not antagonism is the key to biological understanding

Much of the literature on omega-3 and omega-6 fatty acids suggests that desirable effects of omega-3 fatty acids are in part related to depletion of arachidonic acid (AA). However, in rats and humans, we have found that low doses of EPA actually elevate membrane AA phospholipid concentrations. In patients with schizophrenia, treatment with eicosapentaenoic acid (EPA) produced clinical improvement, but that improvement was greater at a dose of 2 g/day than at 4 g/day. The improvement was not significantly correlated with changes in either EPA or docosahexaenoic acid (DHA) but was highly significantly positively correlated with rises in red cell membrane AA. We suggest that elevation of concentrations of both AA and EPA in cell membranes may be important for health.

Education, lifestyle factors and mortality from cardiovascular disease and cancer. A 25-year follow-up of Swedish 50-year-old men

BACKGROUND

There is a well-established inverse relation between education and mortality from cardiovascular disease and cancer. The reasons for this are still in part unclear. We aimed to investigate whether differences in traditional vascular risk factors, adult height, physical activity, and biomarkers of fatty acid and antioxidant intake, could explain this association.

METHODS

In all, 2301 50-year-old men in Uppsala, Sweden (82% of the background population) were examined with regard to educational level, blood pressure, blood glucose, body mass index, serum lipids, smoking, body height, physical activity, serum beta carotene, alpha tocopherol, selenium, and serum fatty acids in cholesterol esters. Cause-specific mortality was registered 25 years later.

RESULTS

Low education was associated with a higher rate of mortality from cardiovascular disease (crude relative risk [RR] = 1.67, 95% CI : 1.17-2.39), and from cancer (crude RR = 1.94, 95% CI : 1.21-3.10), compared to high educational attainment. Men with high education had an overall more beneficial risk factor profile concerning traditional cardiovascular risk factors, physical activity, and biomarkers of dietary intake of antioxidants and fat. After adjustment for all examined risk factors, the inverse gradient between education and cardiovascular mortality disappeared (RR in low education = 1.01. 95% CI : 0.67-1.52). Controlling for smoking, physical activity and dietary biomarkers explained less than half of the excess cancer mortality in the lower educational groups. Smoking (adjusted RR = 1.89, 95% CI : 1.37-2.61), and high proportions of palmitoleic acid in serum cholesterol esters (adjusted RR per 1 SD = 1.39, 95% CI : 1.07-1.82) predicted cancer mortality, independently of all other factors. There were no independent relations between serum antioxidants and mortality.

CONCLUSIONS

These data indicate that modifiable lifestyle factors mediate the inverse gradient between education and death from cerebro- and cardiovascular disease. Smoking, physical activity and dietary factors explained half of the excess cancer mortality in lower educated groups. Further studies are needed to explore the proposed association between palmitoleic acid, a marker of high intake of animal and dairy fat, and cancer.

High plasma nonesterified fatty acids are predictive of cancer mortality but not of coronary heart disease mortality: results from the Paris Prospective Study

To assess the association of fasting plasma nonesterified fatty acid (NEFA) concentration with the risk of death from coronary heart disease and cancer, the authors computed 15-year mortality rates for the 4,589 working men aged 43-53 years who were included in the Paris Prospective Study between 1967 and 1972. A total of 251 and 126 men died from cancer and coronary heart disease, respectively. For coronary heart disease death, the age- and tobacco-adjusted relative risk for men in the highest 20% of the fasting plasma NEFA concentrations compared with those in the lowest 80% was 1.54 (95% confidence interval (CI): 1.01, 2.34). It became nonsignificant after further adjustment for blood pressure, iliac/thigh ratio, and plasma insulin and cholesterol concentrations. In contrast, a high fasting plasma NEFA concentration exhibited a strong independent relation with cancer mortality (relative risk = 1.66, 95% CI: 1.25, 2.21, after adjustment for age, cigarette consumption, heart rate, and body mass index). Despite pathophysiologic mechanisms linking NEFA metabolism with visceral fat and plasma glucose, insulin, and triglyceride concentrations, the plasma NEFA concentration does not appear to be a good marker for coronary heart disease risk. In contrast, an unexpected association with cancer mortality was found that may point to the need for further investigation.

The importance of linoleic acid metabolites in cancer metastasis and in the synthesis and actions of 13-HODE

Large scale human epidemiological studies indicate that high intakes of linoleic acid protect against the development of cancer. One mechanism may be the generation of 13-HODE from linoleic acid. 13-HODE prevents cell adhesion to endothelial cells and can inhibit cancer metastasis. 13-HODE synthesis is enhanced by cyclic AMP. Gamma-linolenic acid, a desaturated metabolite of linoleic acid, causes substantial stimulation of 13-HODE synthesis. A fall in gamma-linolenic acid synthesis with age may be related to the age-related fall in 13-HODE formation.

Subcutaneous, omentum and tumor fatty acid composition, and serum insulin status in patients with benign or cancerous ovarian or endometrial tumors. Do tumors preferentially utilize polyunsaturated fatty acids?

The relationships between the fatty acid composition of cancerous endometrium and ovary, and peripheral adipose tissues were studied in Israeli Jewish women, and are presented together since no differences were shown between them. The results suggest a mobilization of linoleic acid from subcutaneous and omental depots and its incorporation into tumors accompanied by a high degree of desaturation. High blood insulin concentrations characterized patients with stage I and II disease, and low concentrations characterized patients with advanced degrees of malignancy.

Alcohol consumption, gamma-glutamyl transpeptidase (GGT), and pulmonary function: a cross-sectional and longitudinal study in working men

Epidemiological studies of the relationships between pulmonary function and reported alcohol intake showed inconsistent results. The use of biological markers of alcohol is needed. The objective of this study was to assess the relationships of alcohol consumption, assessed by a standardized questionnaire, and gamma-glutamyl transpeptidase (GGT), to forced expiratory volume in 1 sec (FEV1) level and decline over 10 years, in working men. Three hundred twenty-eight policemen aged 22-55 years were examined in 1980 (first survey) and again in 1990 (second survey). The two cross-sectional analyses used the 1980 data and the 1990 data separately. Longitudinal analysis used 1980 alcohol consumption and GGT values, and 10-year FEV1 decline. In both cross-sectional surveys, elevated alcohol consumption was significantly associated with impaired age-adjusted and height-adjusted FEV1. Further adjustment for smoking habit, education level, and asthmatic status did not alter these results. An increase of 25 g/day of alcohol was associated with 50.0 ml (95% confidence interval: 1.5 to 98.5) and 55.3 ml (95% confidence interval: 7.8 to 102.8) decrease of corresponding multivariate-adjusted FEV1 in 1980 and in 1990, respectively. GGT was also negatively associated with FEV1 in both cross-sectional surveys. Similar patterns of associations were also observed between vital capacity measurements and alcohol variables. In the longitudinal analysis, there was no relationship between either alcohol consumption or GGT and FEV1 decline. Findings suggest that alcohol consumption was associated with impaired lung function, but there was no evidence of accelerated FEV1 decline over 10 years related to alcohol consumption in this "healthy" population of middle-aged men.