Highly unsaturated (n-3) fatty acids, but not alpha-linolenic, conjugated linoleic or gamma-linolenic acids, reduce tumorigenesis in Apc(Min/+) mice

EPA, DHA, and resolvin effects on cancer risk: The underexplored mechanisms

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) supplements have exhibited inconsistent effects on cancer risk, and their potential efficacy as cancer preventive agents has been increasingly questioned, especially in recent large randomized clinical trials. The role of host factors that govern EPA and DHA metabolism in relation to their impact on carcinogenesis remains understudied. Resolvins, the products of EPA and DHA oxidative metabolism, demonstrate intriguing antitumorigenic effects through mechanisms such as promoting macrophage phagocytosis of cell debris and inhibiting the production of proinflammatory chemokines and cytokines by tumor-associated macrophages (TAMs), which are crucial for cancer progression. However, clinical studies have not yet shown a significant increase in target tissue levels of resolvins with EPA and DHA supplementation. 15-Lipoxygenase-1 (ALOX15), a key enzyme in EPA and DHA oxidative metabolism, is often lost in various major human cancers, including precancerous and advanced colorectal cancers. Further research is needed to elucidate whether the loss of ALOX15 expression in colorectal precancerous and cancerous cells affects EPA and DHA oxidative metabolism, the formation of resolvins, and subsequently carcinogenesis. The findings from these studies could aid in the development of novel and effective chemoprevention interventions to reduce cancer risk.

Colorectal ALOX15 as a host factor determinant of EPA and DHA effects on colorectal carcinogenesis

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), omega-3 polyunsaturated fatty acids (ω-3 PUFAs) derived from fish oil, are widely used as dietary supplements and FDA-approved treatments for hypertriglyceridemia. However, studies investigating the effects of EPA and DHA on colorectal carcinogenesis (CRC) have yielded conflicting results. The factors that determine these discrepant results remain unknown. Resolvins, oxidative metabolites of EPA and DHA, inhibit key pro-tumorigenic cytokine and chemokine signaling of colorectal cancer (e.g., IL-6, IL-1β, and CCL2). 15-lipoxygenase-1 (ALOX15), a critical enzyme for resolvin generation is commonly lost during human CRC. Whether ALOX15 expression, as a host factor, modulates the effects of EPA and DHA on CRC remains unknown. Therefore, we evaluated the effects of ALOX15 transgenic expression in colonic epithelial cells on resolvin generation by EPA and DHA and CRC in mouse models representative of human CRC. Our results revealed that 1) EPA and DHA effects on CRC were diverse, ranging from suppressive to promotive, and these effects were occasionally altered by the formulations of EPA and DHA (free fatty acid, ethyl ester, triglyceride); 2) EPA and DHA uniformly suppressed CRC in the presence of intestinal ALOX15 transgenic expression, which induced the production of resolvins, decreased colonic CCL3-5 and CXCL-5 expression and tumor associated macrophages while increasing CD8 T cell abundance in tumor microenvironment; and 3) RvD5, the predominant resolvin produced by ALOX15, inhibited macrophage generation of pro-tumorigenic cytokines. These findings demonstrate the significance of intestinal ALOX15 expression as a host factor in determining the effects of EPA and DHA on CRC.

Significance

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are widely used as dietary supplements and FDA-approved treatments for hypertriglyceridemia. Studies of EPA and DHA effects on colorectal carcinogenesis (CRC) have revealed inconsistencies; factors determining the direction of their impact on CRC have remained unidentified. Our data show that EPA and DHA effects on CRC were divergent and occasionally influenced by their formulations. More importantly, intestinal 15-lipoxgenase-1 (ALOX15) expression modulated EPA and DHA effects on CRC, leading to their consistent suppression of CRC. ALOX15 promoted EPA and DHA oxidative metabolism to generate resolvins, which inhibited key pro-tumorigenic inflammatory cytokines and chemokines, including IL-6. IL-1β, and CCL2. ALOX15 is therefore an important host factor in determining EPA and DHA effects on CRC.

Dietary fish and omega-3 polyunsaturated fatty acids intake and cancer survival: A systematic review and meta-analysis

Fish and omega-3 polyunsaturated fatty acids (PUFA) have been suggested to play a role in improving cancer prognosis. However, results from epidemiological studies remain inconsistent. Here we assess the association between dietary fish and/or omega-3 PUFAs intake and cancer prognosis with meta-analysis of observational studies. A systematic search of related publications was performed using PubMed and Web of Science databases. Hazard ratios (HR) and 95% confidence intervals (CI) were extracted and then pooled using a random-effect model. Potential linear and non-linear dose-response relationships were explored using generalized least squares estimation and restricted cubic splines. As a result, 21 cohort studies were included in our analysis. Compared to the lowest category, the highest category of fish intake was associated with a significant lower mortality in patients with ovarian cancer (n = 1, HR = 0.74, 95% CI: 0.57-0.95) and overall cancer (n = 12, HR = 0.87, 95% CI: 0.81-0.94). Marine omega-3 PUFAs intake rather than total omega-3 PUFAs intake showed significant protective effects on survival of overall cancer (n = 8, HR = 0.81, 95% CI: 0.71-0.94), in particular prostate cancer (n = 2, HR = 0.62, 95% CI: 0.46-0.82). Dose-response meta-analysis indicated a nonlinear and a linear relationship between fish intake, as well as marine omega-3 PUFAs intake, and overall cancer survival, respectively. In conclusion, our analysis demonstrated a protective effect of dietary fish and marine omega-3 PUFAs consumption on cancer survival.

The Effects of Conjugated Linoleic Acids on Cancer

Conjugated linoleic acids (CLA) are distinctive polyunsaturated fatty acids. They are present in food produced by ruminant animals and they are accumulated in seeds of certain plants. These naturally occurring substances have demonstrated to have anti-carcinogenic activity. Their potential effect to inhibit cancer has been shown in vivo and in vitro studies. In this review, we present the multiple effects of CLA isomers on cancer development such as anti-tumor efficiency, anti-mutagenic and anti-oxidant activity. Although the majority of the studies in vivo and in vitro summarized in this review have demonstrated beneficial effects of CLA on the proliferation and apoptosis of tumor cells, further experimental work is needed to estimate the true value of CLA as a real anti-cancer agent.

Dual Behavior of Long-Chain Fatty Acids and Their Cyclooxygenase/Lipoxygenase Metabolites on Human Intestinal Caco-2 Cell Growth

Etiology of colorectal cancer (CRC) is related, at least in part, with nutritional profile and epidemiological data indicating a key role of dietary fat on CRC pathogenesis. Moreover, inflammation and eicosanoids produced from arachidonic acid might have a pivotal role in CRC development. However, the effect of specific fatty acids (FAs) on intestinal epithelial cell growth is not completely studied now. By this reason, the aim of this work is to unravel the effect of different saturated and unsaturated long-chain fatty acids (LCFA) and some LCFA metabolites on CRC cell line growth and their possible mechanisms of action. Our results demonstrated that oleic acid is a potent mitogenic factor to Caco-2 cells, at least in part, through 10-hydroxy-8-octadecenoic synthesized by lipoxigenase pathway, whereas polyunsaturated FAs such as eicosapentaenoic (EPA) acid has a dual behavior effect depending on its concentration. A high concentration, EPA induced apoptosis through intrinsic pathway, whereas at low concentration induced cell proliferation that could be related to the synthesis of eicosanoids such as prostaglandin E₃ and 12-hydroxyeicosapentaenoic acid and the subsequent induction of mitogenic cell signaling pathways (ERK 1/2, CREB, p38α). Thus, this study contributes to understand the complicated relationship between fat ingest and CRC.

Plant- and Fish-Derived n-3 PUFAs Suppress Citrobacter Rodentium-Induced Colonic Inflammation

SCOPE

Marine-derived n-3 PUFAs may ameliorate inflammation associated with inflammatory bowel diseases. Plant-derived n-3 PUFAs are thought to be inferior owing to shorter chain lengths. The aim of this study is to compare the impact of plant- and fish-derived PUFAs on murine colitis.

METHODS AND RESULTS

C57BL/6 mice are fed high fat (36% kcal) diets with either 2.5% w/w sunflower oil (SO), flaxseed oil (FSO), ahiflower oil (AO), or fish oil (FO). After 4 weeks, mice are orogastrically challenged with Citrobacter rodentium (10⁸ CFU) or sham gavaged. Fecal shedding is assayed at 2, 7, 10, and 14 days post infection (PI), and fecal microbiota at 14 days PI. Colonic inflammation and lipid mediators are measured. Supplementation regulates intestinal inflammation with crypt lengths being 66, 73, and 62 ±17 µm shorter (compared to SO) for FSO, AO, and FO respectively, p < 0.01. FSO blunts pathogen shedding at the peak of infection and FSO and AO both enhance fecal microbial diversity. FO attenuates levels of lipoxin and leukotriene B₄ while plant oils increase pro-resolving mediator concentrations including D, E, and T-series resolvins.

CONCLUSION

Plant and fish n-3 PUFAs attenuate colitis-induced inflammation while exhibiting characteristic pro-resolving lipid mediator metabolomes. Plant oils additionally promote microbial diversity.

Influence of iron-deficient diets during gestation and lactation on cerebral fatty acids and eicosanoids in guinea pig offspring-Comparison of studies with different sources of dietary lipids

Previous studies showed that mild iron deficiency anaemia (IDA) induced by feeding an iron deficient (ID) diet to female guinea pigs during gestation and lactation to alters the auditory functions of the offspring when corn oil is the only source of dietary lipids. Conversely, feeding an ID diet with a dietary fatty acid composition similar to that of typical human western diets induced minor impairments. Since tissue fatty acid metabolism is affected by dietary iron, the current study measured the impacts of these ID diets (ID-corn and ID-west) compared to the corresponding iron-sufficient control diets (IS-corn and IS-west) on encephalum fatty acid metabolism in the offspring at post-natal day 24. IDA induced by the ID-corn diet resulted in significant increases in encephalum n-6 PUFA content, but IDA induced by the ID-west diet had little impact on fatty acid profiles compared to the IS-west group. Brain COX II protein expression and FADS2 mRNA expression were statistically unaffected in both experiments, but encephalum PGE₂ concentrations were significantly reduced in ID-west pups. These results suggest IDA studies during prenatal development should consider dietary lipid compositions.

Genetic Modification of Mucor circinelloides to Construct Stearidonic Acid Producing Cell Factory

Stearidonic acid (SDA; 18:4, n-3) is the delta 15-desaturase product of gamma linolenic acid (GLA; 18:3, n-6) and delta 6-desaturase product of alpha linolenic acid (ALA; 18:3, n-3). Construction of engineered oleaginous microbes have been attracting significant interest in producing SDA because of its nutritional value and pharmaceutical applications. Mucor circinelloides is a GLA producing filamentous fungus, which can be a useful tool to produce SDA. This study has, therefore, overexpressed the delta-15 desaturase (D15D) gene from Mortierella alpina in this fungus to construct a SDA-producing cell factory. To produce SDA in M. circinelloides, the homologous overexpression of D15D gene was analyzed. When the gene was overexpressed in M. circinelloides CBS 277.49, up to 5.0% SDA was accumulated in this strain. According to current knowledge, this is the first study describing the construction of a SDA-producing cell factory by overexpression of D15D gene in oleaginous fungus M. circinelloides. A new scope for further research has been established by this work to improve SDA production in this fungus, specifically in its high lipid-producing strain, WJ11.

Conjugated Linoleic Acid Effects on Cancer, Obesity, and Atherosclerosis: A Review of Pre-Clinical and Human Trials with Current Perspectives

Obesity and its comorbidities, including type 2 diabetes and cardiovascular disease, are straining our healthcare system, necessitating the development of novel strategies for weight loss. Lifestyle modifications, such as exercise and caloric restriction, have proven effective against obesity in the short term, yet obesity persists because of the high predilection for weight regain. Therefore, alternative approaches to achieve long term sustainable weight loss are urgently needed. Conjugated linoleic acid (CLA), a fatty acid found naturally in ruminant animal food products, has been identified as a potential anti-obesogenic agent, with substantial efficacy in mice, and modest efficacy in obese human populations. Originally described as an anti-carcinogenic fatty acid, in addition to its anti-obesogenic effects, CLA has now been shown to possess anti-atherosclerotic properties. This review summarizes the pre-clinical and human studies conducted using CLA to date, which collectively suggest that CLA has efficacy against cancer, obesity, and atherosclerosis. In addition, the potential mechanisms for the many integrative physiological effects of CLA supplementation will be discussed in detail, including an introduction to the gut microbiota as a potential mediator of CLA effects on obesity and atherosclerosis.

Arachidonic acid and colorectal adenoma risk: a Mendelian randomization study

Background

Previous studies have shown a link between increased dietary intake of arachidonic acid (ARA) and colorectal neoplasms. It has been shown that erythrocyte phospholipid membrane concentrations of ARA are strongly determined by genetic variation. Fatty acid desaturase (FADS) controls the rate limiting step in ARA production, and FADS variant rs174537 has been shown to be responsible for up to 18.6% of the variation seen. To determine if a causal association exists between erythrocyte membrane ARA concentrations and colorectal adenomas, we conducted a Mendelian randomization (MR) analysis using rs174537 as an instrumental variable (IV). MR analysis was chosen because it is less susceptible to bias and confounding.

Patients and methods

A case-control study was performed using the Tennessee Colorectal Polyps Study. Patients were matched on age, gender, race, facility site, and year of colonoscopy. Cases were defined as any colorectal adenoma on colonoscopy (n=909) and controls were polyp free (n=855). A two-stage logistic regression was conducted using rs174537 as the IV with the dependent variable being the presence of a colorectal adenoma on colonoscopy.

Results

Cases were older (59 vs 57 years of age, P<0.0001), and more likely to use alcohol (47.4% vs 19.8%, P=0.001) and to smoke (77.0% vs 66.9%, P<0.0001). There was no statistically significant difference in: age, sex, alcohol use, body mass index (BMI), or NSAID use when stratified by the rs174537 alleles. Genotype was strongly associated with erythrocyte membrane ARA concentrations (P<0.0001). We found no evidence of an association between our IV (rs174537) and colorectal adenomas (P=0.41).

Conclusion

In our MR study increased erythrocyte ARA concentrations were not associated with the risk of colorectal adenomas.

A novel bioactive derivative of eicosapentaenoic acid (EPA) suppresses intestinal tumor development in ApcΔ14/+ mice

Familial adenomatous polyposis (FAP) is a genetic disorder characterized by the development of hundreds of polyps throughout the colon. Without prophylactic colectomy, most individuals with FAP develop colorectal cancer at an early age. Treatment with EPA in the free fatty acid form (EPA-FFA) has been shown to reduce polyp burden in FAP patients. Since high-purity EPA-FFA is subject to rapid oxidation, a stable form of EPA compound has been developed in the form of magnesium l-lysinate bis-eicosapentaenoate (TP-252). We assessed the chemopreventive efficacy of TP-252 on intestinal tumor formation using ApcΔ14/+ mice and compared it with EPA-FFA. TP-252 was supplemented in a modified AIN-93G diet at 1, 2 or 4% and EPA-FFA at 2.5% by weight and administered to mice for 11 weeks. We found that administration of TP-252 significantly reduced tumor number and size in the small intestine and colon in a dose-related manner and as effectively as EPA-FFA. To gain further insight into the cancer protection afforded to the colon, we performed a comprehensive lipidomic analysis of total fatty acid composition and eicosanoid metabolites. Treatment with TP-252 significantly decreased the levels of arachidonic acid (AA) and increased EPA concentrations within the colonic mucosa. Furthermore, a classification and regression tree (CART) analysis revealed that a subset of fatty acids, including EPA and docosahexaenoic acid (DHA), and their downstream metabolites, including PGE3 and 14-hydroxy-docosahexaenoic acid (HDoHE), were strongly associated with antineoplastic activity. These results indicate that TP-252 warrants further clinical development as a potential strategy for delaying colectomy in adolescent FAP patients.

Lipidome in colorectal cancer

Colorectal cancer (CRC) is the second leading cause of cancer-related deaths. Understanding its pathophysiology is essential for developing efficient strategies to treat this disease. Lipidome, the sum of total lipids, related enzymes, receptors and signaling pathways, plays crucial roles in multiple cellular processes, such as metabolism, energy storage, proliferation and apoptosis. Dysregulation of lipid metabolism and function contributes to the development of CRC, and can be used towards the evaluation of prognosis. The strategies targeting lipidome have been applied in clinical trails and showed promising results. Here we discuss recent advances in abnormal lipid metabolism in CRC, the mechanisms by which the lipidome regulates tumorigenesis and tumor progression, and suggest potential therapeutic targets for clinical trials.

Mediterranean Diet: Prevention of Colorectal Cancer

Colorectal cancer (CRC) is the third most common cancer diagnosis and the second and third leading cause of cancer mortality in men and women, respectively. However, the majority of CRC cases are the result of sporadic tumorigenesis via the adenoma–carcinoma sequence. This process can take up to 20 years, suggesting an important window of opportunity exists for prevention such as switching toward healthier dietary patterns. The Mediterranean diet (MD) is a dietary pattern associated with various health benefits including protection against cardiovascular disease, diabetes, obesity, and various cancers. In this article, we review publications available in the PubMed database within the last 10 years that report on the impact of a MD eating pattern on prevention of CRC. To assist the reader with interpretation of the results and discussion, we first introduce indexes and scoring systems commonly used to experimentally determine adherence to a MD, followed by a brief introduction of the influence of the MD pattern on inflammatory bowel disease, which predisposes to CRC. Finally, we discuss key biological mechanisms through which specific bioactive food components commonly present in the MD are proposed to prevent or delay the development of CRC. We close with a discussion of future research frontiers in CRC prevention with particular reference to the role of epigenetic mechanisms and microbiome related to the MD eating pattern.

Dietary LC-PUFA in iron-deficient anaemic pregnant and lactating guinea pigs induce minor defects in the offsprings' auditory brainstem responses

OBJECTIVES

We previously demonstrated that a mild pre-natal/early post-natal iron-deficient anaemic (IDA) diet devoid of long-chain polyunsaturated fatty acids (LC-PUFA) affected development, neurophysiology, and cerebral lipid biochemistry of the guinea pigs' progeny. Impacts of dietary LC-PUFA on altered cerebral development resulting from pre-natal IDA are unknown. To address this health issue, impacts of mild gestational IDA in the presence of dietary LC-PUFA on the offsprings' neural maturation were studied in guinea pigs using auditory brainstem responses (ABRs) and assessments of brain fatty acids (FAs).

METHODS

Female guinea pigs (n = 10/group) were fed an iron sufficient (IS) or IDA diet (146 and 12.7 mg iron/kg, respectively) with physiological amounts of LC-PUFA, during the gestation and lactation periods. From post-natal day (PNd) 9 onwards, the IS + PUFA diet was given to both groups of weaned offspring. Cerebral tissue and offsprings' ABR were collected on PNd24.

RESULTS

There was no difference in peripheral and brainstem transmission times (BTTs) between IS + PUFA and IDA + PUFA siblings (n = 10/group); the neural synchrony was also similar in both groups. Despite the absence of differences in auditory thresholds, IDA + PUFA siblings demonstrated a sensorineural hearing loss in the extreme range of frequencies (32, 4, and 2 kHz), as well as modified brain FA profiles compared to the IS + PUFA siblings.

DISCUSSION

The present study reveals that siblings born from dams exposed to a moderate IDA diet including balanced physiological LC-PUFA levels during pregnancy and lactation demonstrate minor impairments of ABR compared to the control siblings, particularly on the auditory acuity, but not on neural synchrony, auditory nerve velocity and BTT.

Dietary walnut suppression of colorectal cancer in mice: Mediation by miRNA patterns and fatty acid incorporation

Colorectal cancer, unlike many other malignancies, may be preventable. Recent studies have demonstrated an inverse association between nut consumption and incidence of colon cancer; however, the underlying mechanisms are not fully understood. An emerging concept suggests that microribonucleic acids (miRNAs) may help explain the relationship between walnut consumption and decreased colorectal neoplasia risk. Seven days after HT-29 colon cancer cell injection, mice were randomized to either control or walnut diets for 25 days of diet treatment. Thirty samples of tumor and of omental adipose were analyzed to determine changes in lipid composition in each dietary group. In the tumors of the walnut-containing diet, we found significant increases in α-linolenic, eicosapentaenoic, docosahexaenoic and total omega-3 acids, and a decrease in arachidonic acid, as compared to the control diet. Final tumor size measured at sacrifice was negatively associated with percentage of total omega-3 fatty acid composition (r=-0.641, P=.001). MicroRNA expression analysis of colorectal tumor tissue revealed decreased expression of miRNAs 1903, 467c and 3068 (P<.05) and increased expression of miRNA 297a* (P=.0059) in the walnut-treated group as compared to control diet. Our results indicate that changes in the miRNA expression profiles likely affect target gene transcripts involved in pathways of anti-inflammation, antivascularization, antiproliferation and apoptosis. We also demonstrate the incorporation of protective fatty acids into colonic epithelium of walnut-fed mice, which may independently alter miRNA expression profiles itself. Future studies of the mechanism of widespread miRNA regulation by walnut consumption are needed to offer potential prognostic and therapeutic targets.

Dietary conjugated linoleic acid alters oxidative stability and alleviates plasma cholesterol content in meat of broiler chickens

This study was conducted to investigate the effects of dietary conjugated linoleic acid (CLA) on fatty acid composition, lipoprotein content, lipid peroxidation, and meat colour of broiler chickens. A total of 180 broiler chickens were allocated to 3 dietary treatments (0, 2.5, and 5% Lutrell) and given a standard broiler starter diet and finisher diet. Body weight of chickens and feed intake were recorded weekly. After slaughter, the breast meat was aged at 4 °C for 0, 3, and 6 days. The fatty acid composition was measured in the breast meat. Body weight (BW) and feed efficiency were decreased by dietary CLA level (P < 0.05). Chicken fed with 2.5% Lutrell had the highest feed intake compared to the control (CON) group. The total CLA increased significantly (P < 0.05) in breast meat from birds supplemented with CLA. Propensity for lipid peroxidation was significantly higher after 6 days of meat storage (P < 0.05) and the redness in chicken breast meat was lower in CLA-fed birds (P < 0.05). It is also notable that a 5% Lutrell supplementation decreased the plasma total cholesterol (TC), low density protein (LDL), and HDL (high-density lipoprotein)/LDL ratio in chickens (P < 0.05).

Essential fatty acids as functional components of foods- a review

During the recent decades, awareness towards the role of essential fatty acids in human health and disease prevention has been unremittingly increasing among people. Fish, fish oils and some vegetable oils are rich sources of essential fatty acids. Many studies have positively correlated essential fatty acids with reduction of cardiovascular morbidity and mortality, infant development, cancer prevention, optimal brain and vision functioning, arthritis, hypertension, diabetes mellitus and neurological/neuropsychiatric disorders. Beneficial effects may be mediated through several different mechanisms, including alteration in cell membrane composition, gene expression or eicosanoid production. However, the mechanisms whereby essential fatty acids affect gene expression are complex and involve multiple processes. Further understanding of the molecular aspects of essential fatty acids will be the key to devising novel approaches to the treatment and prevention of many diseases.

Adipose tissue fatty acid composition and colon cancer: a case-control study

PURPOSE

An increased dietary intake of fat, particularly polyunsaturated fatty acids (PUFAs), has been related to an increased risk of breast, prostate and colon cancers. Patients with and without colon cancer were tested for differences in their fatty stores composition.

METHODS

The fatty acid levels were determined by gas-liquid chromatography in adipose tissue samples, subcutaneous and visceral, obtained intra-operatively from 52 colon cancer and 50 nonneoplastic abdominal disease patients. Statistical analysis was performed using one-way ANOVA, SNK test and Dunnet test. Differences in the composition of saturated, monounsaturated and polyunsaturated fatty acids, in visceral and in subcutaneous samples of colon cancer and nonneoplastic patients, were assessed.

RESULTS

The sum of saturated and monounsaturated fatty acids, respectively, in visceral and in subcutaneous samples, was higher in neoplastic patients (p < 0.001). The sum of some n-6 polyunsaturated fatty acids (PUFAs), the dietary precursor linoleic acid (LA-18:2n-6), and their metabolites, gammalinolenic acid (GLA-18:3n-6) + dihomogammalinolenic acid (DGLA-20:3n-6) + arachidonic acid (AA-22:4n-6), was higher in subcutaneous fat of controls (p < 0.05). The samples from these patients had a fatty acid composition, both subcutaneous and visceral, with a higher content of alphalinolenic acid (ALA-18:3n-3) and stearidonic acid (SDA-18:4n-3) compared to neoplastic patients (p < 0.001). These had subcutaneous and visceral fat stores statistically higher in GLA, DGLA and AA (p < 0.001). Colon cancer patients had subcutaneous adipose stores higher in ALA and LA than visceral sites (p < 0.001).

CONCLUSIONS

Fatty acids may be involved in colon carcinogenesis and there is a depot-specific impact on this process by visceral fat.

Dietary omega-3 PUFA and health: stearidonic acid-containing seed oils as effective and sustainable alternatives to traditional marine oils

The daily consumption of dietary omega-3 PUFA is recommended by governmental agencies in several countries and by a number of health organizations. The molecular mechanisms by which these dietary PUFA affect health involve the enrichment of cellular membranes with long-chain 20- and 22-carbon omega-3 PUFA that impacts tissues by altering membrane protein functions, cell signaling, and gene expression profiles. These changes are recognized to have health benefits in humans, especially relating to cardiovascular outcomes. Cellular membrane enrichment and health benefits are associated with the consumption of long-chain omega-3 PUFA found in marine oils, but are not generally linked with the consumption of alpha-linolenic acid, the 18-carbon omega-3 PUFA found in plant seed oils. However, the supply of omega-3 PUFA from marine sources is limited and may not be sustainable. New plant-derived sources of omega-3 PUFA like stearidonic acid-soy oil from genetically modified soybeans and Ahiflower oil from Buglossoides arvensis seeds that are enriched in the 18-carbon omega-3 PUFA stearidonic acid are being developed and show promise to become effective as well as sustainable sources of omega-3 PUFA. An example of changes in tissue lipid profiles associated with the consumption of Ahiflower oil is presented in a mouse feeding study.

Dietary intake of n-3 fatty acids and colorectal cancer risk: a meta-analysis of data from 489 000 individuals

Preclinical studies have suggested an anti-colorectal cancer effect of n-3 fatty acids, yet epidemiological studies have reported mixed results. The goal of the present meta-analysis was to examine the association between the dietary intake of n-3 fatty acids and colorectal cancer risk by conducting a meta-analysis of prospective cohort studies. We searched the PubMed database up to February 2012 to identify eligible studies. Either a fixed- or random-effects model was used to obtain a pooled relative risk (RR) comparing the highest intake of n-3 fatty acids with the lowest. We conducted subgroup analyses according to sex, geographic region, length of follow-up, cancer site and type of n-3 fatty acids. We included seven prospective studies in the meta-analysis, comprising 489 465 participants and 4656 incident cases. The pooled RR of colorectal cancer in relation to n-3 fatty acids was 0·98 (95 % CI 0·88, 1·09). The results from subgroup analysis indicated a significant reduced risk of colorectal cancer in relation to n-3 fatty acids among men (RR 0·87, 95 % CI 0·75, 1·00; n 4). No significant association was observed in other subgroups. There was no evidence of publication bias as suggested by Begg's test (P = 0·76) and Egger's test (P = 0·66). The present meta-analysis showed insufficient evidence of a protective effect of n-3 fatty acids on colorectal cancer risk. However, a reduced risk observed in men warrants further investigation.

Dietary intake of PUFAs and colorectal polyp risk

BACKGROUND

Marine-derived n-3 (omega-3) PUFAs may reduce risk of developing colorectal cancer; however, few studies have investigated the association of n-3 PUFA intakes on colorectal polyp risk.

OBJECTIVE

The objective of this study was to examine the associations of dietary PUFA intake on risk of colorectal adenomatous and hyperplastic polyps.

DESIGN

This was a colonoscopy-based case-control study that included 3166 polyp-free control subjects, 1597 adenomatous polyp cases, and 544 hyperplastic polyp cases. Dietary PUFA intake was calculated from food-frequency questionnaires and tested for association by using unconditional logistic regression. The urinary prostaglandin E(2) metabolite, which is a biomarker of prostaglandin E(2) production, was measured in 896 participants by using liquid chromatography and tandem mass spectrometry.

RESULTS

n-6 PUFAs were not associated with adenomatous or hyperplastic polyps in either men or women. Marine-derived n-3 PUFAs were associated with reduced risk of colorectal adenomas in women only, with an adjusted OR of 0.67 (95% CI: 0.47, 0.97) for the highest quintile of intake compared with the lowest quintile of intake (P-trend = 0.01). Dietary intake of α-linolenic acid was associated with an increased risk of hyperplastic polyps in men (P-trend = 0.03), which was not seen in women. In women, but not in men, dietary intake of marine-derived n-3 PUFAs was negatively correlated with urinary prostaglandin E(2) production (r = -0.18; P = 0.002).

CONCLUSION

Higher intakes of marine-derived n-3 PUFAs are associated with lower risk of adenomatous polyps in women, and the association may be mediated in part through a reduction in the production of prostaglandin E(2). This trial was registered at clinicaltrials.gov as NCT00625066.

A high-fat diet containing whole walnuts (Juglans regia) reduces tumour size and growth along with plasma insulin-like growth factor 1 in the transgenic adenocarcinoma of the mouse prostate model

Prostate cancer (PCa) has been linked to fat intake, but the effects of both different dietary fat levels and types remain inconsistent and incompletely characterised. The effects on PCa in the transgenic adenocarcinoma of the mouse prostate (TRAMP) cancer model of an elevated fat (20 % of energy as fat) diet containing 155 g of whole walnuts were compared to those of an elevated fat (20 % of energy as soyabean oil) diet with matched macronutrients, tocopherols as well as a low-fat (8 % of energy as soyabean oil) diet. Mice, starting at 8 weeks of age, consumed one of the three different diets ad libitum; and prostates, livers and blood were obtained after 9, 18 or 24 weeks of feeding. No differences were observed in whole animal growth rates in either high-fat (HF) diet group, but prostate tumour weight and growth rate were reduced in the walnut diet group. Walnut diet group prostate weight, plasma insulin-like growth factor 1, resistin and LDL were lower at 18 weeks, while no statistically significant prostate weight differences by diet were seen at 9 or 24 weeks. Multiple metabolites in the livers differed by diet at 9 and 18 weeks. The walnut diet's beneficial effects probably represent the effects of whole walnuts' multiple constituents and not via a specific fatty acid or tocopherols. Moreover, as the two HF diets had dissimilar effects on prostate tumour growth rate and size, and yet had the same total fat and tocopherol composition and content, this suggests that these are not strongly linked to PCa growth.

Dietary walnut suppressed mammary gland tumorigenesis in the C(3)1 TAg mouse

Walnuts contain multiple ingredients that, individually, have been shown to slow cancer growth, including omega-3 fatty acids, antioxidants, and phytosterols. In previous research, consumption of walnuts has slowed the growth of implanted breast cancers. We wanted to determine whether regular walnut consumption might reduce the risk for developing cancer. Homozygous male C(3)1 TAg mice were bred with female SV129 mice consuming either the control AIN-76 diet or the walnut-containing diet. At weaning, the female hemizygous pups were randomized to control or walnut-containing diets and followed for tumor development. Compared to a diet without walnuts, consumption of walnuts significantly reduced tumor incidence (fraction of mice with at least one tumor), multiplicity (number of glands with tumor/mouse), and size. Gene expression analyses indicated that consumption of the walnut diet altered expression of multiple genes associated with proliferation and differentiation of mammary epithelial cells. A comparison with another dietary intervention indicated that the omega 3 content alone did not account for the extent of tumor suppression due to the walnut. The results of this study indicate that walnut consumption could contribute to a healthy diet to reduce risk for breast cancer.

Allometric scaling of dietary linoleic acid on changes in tissue arachidonic acid using human equivalent diets in mice

Background

It is hypothesized that dietary linoleic acid (LA) promotes chronic and acute diseases in humans by enriching tissues with arachidonic acid (AA), its downstream metabolite, and dietary studies with rodents have been useful for validation. However, levels of LA in research diets of rodents, as published in the literature, are notoriously erratic making interspecies comparisons unreliable. Therefore, the ability to extrapolate the biological effects of dietary LA from experimental rodents to humans necessitates an allometric scaling model that is rooted within a human equivalent context.

Methods

To determine the physiological response of dietary LA on tissue AA, a mathematical model for extrapolating nutrients based on energy was used, as opposed to differences in body weight. C57BL/6J mice were divided into 9 groups fed a background diet equivalent to that of the US diet (% energy) with supplemental doses of LA or AA. Changes in the phospholipid fatty acid compositions were monitored in plasma and erythrocytes and compared to data from humans supplemented with equivalent doses of LA or AA.

Results

Increasing dietary LA had little effect on tissue AA, while supplementing diets with AA significantly increased tissue AA levels, importantly recapitulating results from human trials.

Conclusions

Thus, interspecies comparisons for dietary LA between rodents and humans can be achieved when rodents are provided human equivalent doses based on differences in metabolic activity as defined by energy consumption.

Highly purified eicosapentaenoic acid as free fatty acids strongly suppresses polyps in Apc(Min/+) mice

PURPOSE

Although cyclooxygenase (COX)-2 inhibitors could represent the most effective chemopreventive tool against colorectal cancer (CRC), their use in clinical practice is hampered by cardiovascular side effects. Consumption of ω-3-polyunsaturated fatty acids (ω-3-PUFAs) is associated with a reduced risk of CRC. Therefore, in this study, we assessed the efficacy of a novel 99% pure preparation of ω-3-PUFA eicosapentaenoic acid as free fatty acids (EPA-FFA) on polyps in Apc(Min/+) mice.

EXPERIMENTAL DESIGN

Apc(Min/+) and corresponding wild-type mice were fed control diet (Ctrl) or diets containing either EPA-FFA 2.5% or 5%, for 12 weeks while monitoring food intake and body weight.

RESULTS

We found that both EPA-FFA diets protected from the cachexia observed among Apc(Min/+) animals fed Ctrl diet (P < 0.0054), without toxic effect, in conjunction with a significant decrease in lipid peroxidation in the treated arms. Moreover, both EPA-FFA diets dramatically suppressed polyp number (by 71.5% and 78.6%, respectively; P < 0.0001) and load (by 82.5% and 93.4%, respectively; P < 0.0001) in both small intestine and colon. In addition, polyps less than 1 mm in size were predominantly found in the EPA-FFA 5% arm whereas those 1 to 3 mm in size were more frequent in the Ctrl arm (P < 0.0001). Interestingly, in the EPA-FFA groups, mucosal arachidonic acid was replaced by EPA (P < 0.0001), leading to a significant reduction in COX-2 expression and β-catenin nuclear translocation. Moreover, in the EPA-FFA arms, we found a significant decrease in proliferation throughout the intestine together with an increase in apoptosis.

CONCLUSIONS

Our data make 99% pure EPA-FFA an excellent candidate for CRC chemoprevention.

Reactive oxygen species abrogate the anticarcinogenic effect of eicosapentaenoic acid in Atm-deficient mice

Recent studies have demonstrated that n-3 polyunsaturated fatty acids such as eicosapentaenoic acid (EPA) are able to suppress cell proliferation and inhibit tumor growth. The objective of our study was to investigate the influence of a high dose EPA on the development of the tumor phenotype in ataxia-telangiectasia mutated (Atm)-deficient mice, a genetic cancer model that is associated with increased levels of oxidative stress. We analyzed toxicity, proliferation, cell-cycle progression, and apoptosis of EPA in vitro and latency to tumorigenesis in vivo. Because of the impact of reactive oxygen species (ROS) on the tumor incidence in ataxia telangiectasia (AT), we further analyzed the effect of EPA on the generation of ROS and oxidative DNA damage (ODD). EPA effectively inhibited proliferation, altered cell-cycle progression, and induced apoptosis of tumor cells (AT-4). EPA showed no effect on the latency to tumorigenesis in Atm-deficient mice. EPA treatment was accompanied by a significant increase of ROS and ODD. Our results demonstrate the antiproliferative effect of EPA on tumor cells by alteration of cell-cycle progression and induction of apoptosis in vitro. On the other hand, EPA treatment of Atm-deficient mice led to the formation of ROS and accumulation of ODD that might have abrogated the anticarcinogenic effect caused by EPA.

Dietary oleic acid as a control fatty acid for polyunsaturated fatty acid intervention studies: a transcriptomics and proteomics investigation using interleukin-10 gene-deficient mice

Oleic acid (OA) has been used as a control fatty acid in dietary polyunsaturated fatty acid (PUFA) intervention studies due to its lack of effect on eiconasoid biosynthesis. Since the effect of OA as a control fatty acid has not yet been investigated for transcriptomics and proteomics studies, this study aimed to test whether colonic transcriptome and proteome profiles associated with colitis development in mice fed a linoleic acid-rich corn oil-AIN-76A diet (Il10(-/-) compared to C57 mice) where similar to those of OA-fed Il10(-/-) compared to C57 mice (genotype comparison). A close clustering of colonic gene and protein expression profiles between the mice fed the AIN-76A or OA diet was observed. Inflammation-induced regulatory processes associated with cellular and humoral immune responses, cellular stress response and metabolic processes related to energy utilization were identified in Il10(-/-) compared to C57 mice fed either diet. Thus OA was considered as a suitable control unsaturated fatty acid for use in multi-omics PUFA studies. The second aim of this study was to test the effect of an OA-enriched AIN-76A diet compared to a linoleic acid-rich corn oil-AIN-76A diet on colonic transcriptome and proteome changes within Il10(-/-) or C57 mice (diet comparison). Overall, there was a limited concordance observed between measureable transcriptomics and proteomics profiles for genotype and diet comparisons. This underlines the importance and validity of a systems biology approach to understand the effects of diet on gene expression as a function of the genotype.

Dietary fatty acids, luminal modifiers, and risk of colorectal cancer

Inconsistent observations in epidemiologic studies on the association between total fat intake and colorectal cancer may be ascribed to opposing effects of individual fatty acids and the presence of other dietary constituents that modify luminal or systemic lipid exposure. We analyzed the data from a population-based case-control study that included 1,163 cases and 1,501 controls to examine the effects of individual fatty acid groups on colorectal cancer risk as well as their interactions with calcium and fiber intake. Odds ratios (OR) and 95% confidence intervals (CI) were estimated by unconditional logistic regression model according to quartile levels of energy-adjusted fatty acid intake. In the bivariable analyses, the risk of colorectal cancer increased with trans fatty acid (TFA) intake (OR for top vs. bottom quartile =1.46, 95% CI 1.17-1.59, p-value for a trend <0.001), but the associations was substantially attenuated in multivariable analyses (p value for a trend = 0.176). However, a significant linear trend in the multivariable OR (p = 0.029) for TFA was present for subjects with lower calcium intake. Furthermore, multivariable ORs progressively decreased with increasing both omega-3 and omega-6 poly- unsaturated fatty acid intake (p-values for linear trend: 0.033 and 0.011, respectively) for subjects with lower dietary fiber intake. These interactions were also significant or marginally significant (p = 0.085 for TFA, 0.029 for omega-3 and 0.068 for omega-6). Our results suggest that populations with lower intake of luminal modifiers, i.e., calcium and fiber, may have differential risks of colorectal cancer associated with dietary fatty acid intake.

Intake of polyunsaturated fatty acids and distal large bowel cancer risk in whites and African Americans

Long-chain omega-3 polyunsaturated fatty acids (PUFAs) may have antineoplastic properties in the colon. The authors examined the association between intakes of different PUFAs and distal large bowel cancer in a population-based case-control study of 1,503 whites (716 cases; 787 controls) and 369 African Americans (213 cases; 156 controls) in North Carolina (2001-2006). Unconditional logistic regression was used to estimate odds ratios and 95% confidence intervals for distal large bowel cancer risk in relation to quartiles of PUFA intake. Increased consumption of long-chain omega-3 PUFAs was associated with reduced risk of distal large bowel cancer in whites (multivariable odds ratios = 0.88 (95% confidence interval (CI): 0.63, 1.22), 0.69 (95% CI: 0.49, 0.98), and 0.49 (95% CI: 0.34, 0.71) for second, third, and highest vs. lowest quartile) (P(trend) < 0.01). Intake of individual eicosapentaenoic acids and docosahexaenoic acids was inversely related to distal large bowel cancer risk, whereas the ratio of omega-6 to long-chain omega-3 PUFAs was associated with increased risk of distal large bowel cancer in whites, but not among African Americans (P(interaction) < 0.05). Study results support the hypothesis that long-chain omega-3 PUFAs have beneficial effects in colorectal carcinogenesis. Whether or not the possible benefit of long-chain omega-3 PUFAs varies by race warrants further evaluation.

Mouse models for unraveling the importance of diet in colon cancer prevention

Diet and genetics are both considered important risk determinants for colorectal cancer, a leading cause of death worldwide. Several genetically engineered mouse models have been created, including the ApcMin mouse, to aid in the identification of key cancer related processes and to assist with the characterization of environmental factors, including the diet, which influence risk. Current research using these models provides evidence that several bioactive food components can inhibit genetically predisposed colorectal cancer, while others increase risk. Specifically, calorie restriction or increased exposure to n-3 fatty acids, sulforaphane, chafuroside, curcumin and dibenzoylmethane were reported protective. Total fat, calories and all-trans retinoic acid are associated with an increased risk. Unraveling the importance of specific dietary components in these models is complicated by the basal diet used, the quantity of test components provided and interactions among food components. Newer models are increasingly available to evaluate fundamental cellular processes, including DNA mismatch repair, immune function and inflammation as markers for colon cancer risk. Unfortunately, these models have been used infrequently to examine the influence of specific dietary components. The enhanced use of these models can shed mechanistic insights about the involvement of specific bioactive food and components and energy as determinants of colon cancer risk. However, the use of available mouse models to exactly represent processes important to human gastrointestinal cancers will remain a continued scientific challenge.

Antineoplastic effects of n-3 polyunsaturated fatty acids in combination with drugs and radiotherapy: preventive and therapeutic strategies

Many data support the beneficial effect of n-3 polyunsaturated fatty acids (PUFAs) as chemopreventive and chemotherapeutic agents in the treatment of several chronic pathologies including cancer. Different molecular mechanisms have been proposed to explain their effects, including alterations in arachidonic acid oxidative metabolism and metabolic conversion of n-3 PUFAs to novel discovered bioactive derivatives; modification of oxidative stress; changes in cell membrane fluidity and structure and altered metabolism and function of membrane proteins. Considerable knowledge has been recently gathered on the possible beneficial effects of n-3 PUFAs administered in combination with different antineoplastic drugs and radiotherapy against melanoma, leukemia, neuroblastoma, and colon, breast, prostate, and lung cancer. The efficacy of these combinations has been demonstrated both in vivo and in vitro, and clinical trials have also been conducted. The aim of this review is to analyze all the n-3 PUFA combinations investigated so far, their efficacy, and the possible molecular mechanisms involved. It would be highly auspicable that the detailed analysis of the literature in this field could further support the common use of n-3 PUFAs in combination with other chemopreventive agents and warrant more clinical investigations designed to test the effectiveness of n-3 PUFA treatments coupled with conventional antineoplastic therapies.

Linseed oil in the maternal diet during gestation and lactation modifies fatty acid composition, mucosal architecture, and mast cell regulation of the ileal barrier in piglets

In this study, we investigated the effect of supplementation of the maternal diet with linseed oil [rich in 18:3(n-3)] on fatty acid composition, mucosal architecture, and mast cell regulation of barrier function in piglet ileum. Sixteen sows were fed a lard (LAR)- or a linseed oil (LSO)-based diet during gestation and lactation. Fatty acid composition of maternal RBC at parturition and of milk at d 14 of lactation were determined. Fatty acid composition, villous-crypt structure, and permeability to horseradish peroxidase in Ussing chambers after mast cell degranulation were determined in the ileum of piglets at d 0, 7, and 28. At d 0, 18:3(n-3) and 20:5(n-3) levels were higher, but 22:6(n-3) and 20:4(n-6) levels were lower in both maternal RBC and piglet ileum of the LSO group. Levels of 18:3(n-3) were also higher in the milk of LSO sows. Levels of 18:3(n-3) were higher in LSO piglet ileum at d 7 and 28. Moreover, at d 28, 20:4(n-6) ileal levels tended (P = 0.09) to be lower in LSO than in LAR piglets, in parallel with a lower mRNA expression of Delta5 desaturase. LSO piglets had shorter villi at d 0 and shorter crypts at d 7 compared with LAR piglets. The effect of mast cell degranulation on ileal permeability decreased with age in both groups but reached a minimum sooner in the LSO group (d 7) than in the LAR group (d 28). In conclusion, linseed oil supplementation of the maternal diet profoundly modifies the fatty acid composition, structure, and physiology of the offspring ileum.

A systemic review of the roles of n-3 fatty acids in health and disease

Attention to the role of n-3 long-chain fatty acids in human health and disease has been continuously increased during recent decades. Many clinical and epidemiologic studies have shown positive roles for n-3 fatty acids in infant development; cancer; cardiovascular diseases; and more recently, in various mental illnesses, including depression, attention-deficit hyperactivity disorder, and dementia. These fatty acids are known to have pleiotropic effects, including effects against inflammation, platelet aggregation, hypertension, and hyperlipidemia. These beneficial effects may be mediated through several distinct mechanisms, including alterations in cell membrane composition and function, gene expression, or eicosanoid production. A number of authorities have recently recommended increases in intakes of n-3 fatty acids by the general population. To comply with this recommendation a variety of food products, most notably eggs, yogurt, milk, and spreads have been enriched with these fatty acids. Ongoing research will further determine the tissue distribution, biological effects, cost-effectiveness, and consumer acceptability of such enriched products. Furthermore, additional controlled clinical trials are needed to document whether long-term consumption or supplementation with eicosapentaenoic acid/docosahexaenoic acid or the plant-derived counterpart (alpha-linolenic acid) results in better quality of life.

Dietary stearidonic acid is a long chain (n-3) polyunsaturated fatty acid with potential health benefits

The therapeutic and health-promoting effects of (n-3) long-chain PUFA (LCPUFA) from fish are well known, although these same benefits may not be shared by their precursor, alpha-linolenic acid (ALA). World-wide agencies and scientific organizations (i.e. FDA, AHA, International Society for the Study of Fatty Acids and Lipids, Institute of Medicine, WHO, etc.) have made similar dietary recommendations for (n-3) LCPUFA; however, due to concerns regarding the safety of consuming fish, alternative sources of (n-3) LCPUFA are being investigated. One such lipid is stearidonic acid (SDA), a naturally occurring (n-3) PUFA that may have similar biological properties to eicosapentaenoic acid (EPA), a major (n-3) PUFA in fish oil. Existing and novel plant sources rich in SDA are being cultivated and promoted as potential alternatives to marine-based (n-3) PUFA. This critical review provides a direct comparison of SDA with other dietary (n-3) PUFA under similar experimental conditions. The comparative results suggest that SDA shares many of the biological effects of (n-3) LCPUFA and functions most similarly to dietary EPA compared with ALA when consumed in a typical Western diet. Therefore, although SDA may not replace fish as a major dietary source of (n-3) LCPUFA, it could become a prominent surrogate for EPA in the commercial development of foods fortified with (n-3) PUFA.

Multi-targeted therapy of cancer by omega-3 fatty acids

Omega-3 (n-3) and omega-6 (n-6) polyunsaturated fatty acids (PUFAs) are essential fatty acids necessary for human health. Currently, the Western diet contains a disproportionally high amount of n-6 PUFAs and low amount of n-3 PUFAs, and the resulting high n-6/n-3 ratio is thought to contribute to cardiovascular disease, inflammation, and cancer. Studies in human populations have linked high consumption of fish or fish oil to reduced risk of colon, prostate, and breast cancer, although other studies failed to find a significant association. Nonetheless, the available epidemiological evidence, combined with the demonstrated effects of n-3 PUFAs on cancer in animal and cell culture models, has motivated the development of clinical interventions using n-3 PUFAs in the prevention and treatment of cancer, as well as for nutritional support of cancer patients to reduce weight loss and modulate the immune system. In this review, we discuss the rationale for using long-chain n-3 PUFAs in cancer prevention and treatment and the challenges that such approaches pose in the design of clinical trials.

Dietary n-3 polyunsaturated fatty acids enhance hormone ablation therapy in androgen-dependent prostate cancer

Hormone ablation therapy typically causes regression of prostate cancer and represents an important means of treating this disease, particularly after metastasis. However, hormone therapy inevitably loses its effectiveness as tumors become androgen-independent, and this conversion often leads to death because of subsequent poor responses to other forms of treatment. Because environmental factors, such as diet, have been strongly linked to prostate cancer, we examined the affects of dietary polyunsaturated fatty acids (PUFAs; at 1.5 wt%) on growth of androgen-dependent (CWR22) and androgen-independent (CWR22R) human prostatic cancer xenografts, the acute response of CWR22 tumors to ablation therapy, and their progression to androgen independence. Significant diet-induced changes in tumor n-3 or n-6 PUFA content had no affect on CWR22 or CWR22R tumors growing with or without androgen support, respectively. However, dietary changes that increased tumor eicosapentaenoic acid and linoleic acid content enhanced responses to ablation therapy, measured by cancer cell apoptosis and mitosis. In addition, relapse to androgen-independent growth (measured by renewed increases in tumor volume and serum prostate-specific antigen after ablation) positively correlated with tumor arachidonic acid content. There was no correlation between expression of 15-lipoxygenase isozymes or their products and tumor growth or responses to ablation. In conclusion, dietary n-3 PUFA may enhance the response of prostate cancer to ablation therapy and retard progression to androgen-independent growth by altering tumor PUFA content.