Does chronic essential fatty acid deficiency constitute a pro-tumorigenic condition?

Crosstalk among dietary polyunsaturated fatty acids, urolithiasis, chronic inflammation, and urinary tract tumor risk

Based on a consistent bulk of experimental and epidemiologic works, we proposed that abnormal metabolism and/or dietary deprivation of essential polyunsaturated fatty acids by inducing a chronic and subclinical essential fatty acid deficiency (EFAD) in urothelial cell membranes may enhance the risk for urinary tract tumor (UTT) development. This threat may be enhanced by the unusual fact that the fatty-acid profile of the normal urothelium is similar to that reported in EFAD. The risk for UTT may be worsened when coexisting with a low-grade chronic inflammation (LGCI) state induced by urolithiasis or disbalance management of peroxides, free radical molecules, and their quenchers. There is cumulative evidence linking the LGCI of the urinary tract mucosa, calculi, and UTT, due to the long-standing release of promitotic, promutagen, and pro-inflammatory antiapoptotic cytokines in these conditions. The dual role played by pro- and anti-inflammatory eicosanoids and bioactive lipids, cytokines, and the disbalance of lipid peroxidation is discussed, concluding that the moderate, long-standing consumption or dietary supplementation of ω-3 PUFAs may improve the chances of avoiding UTT development.

Dietary habits and prostate cancer prevention: a review of observational studies by focusing on South America

There exist several works considering the association between diet and prostate cancer (PC) risk, but the issue is largely unsettled. This article systematically reviews the epidemiological studies on diet and risk of PC focusing on those carried out in countries of South America. There is some suggestion that dairy products, red meat, processed meat, α-linolenic fatty acids, as well as dietary patterns characterized by higher intakes of red and processed meat, eggs, and grains may play some role in the development of PC. There is no clear association with the intake of vegetables and fruits, lycopene, fats, and different types of fatty acids. The evidence on diet and PC is therefore inconclusive in general and specifically in South America. Particular attention must be paid to the study of cancer risk in some countries of South America because of the singularly risky dietary pattern consumed by its population.

Selective COX-2 inhibition affects fatty acids, but not COX mRNA expression in patients with FAP

Familial adenomatous polyposis (FAP) provides a model for sporadic colorectal cancer development. Cyclooxygenase (COX) inhibition may ameliorate polyp development, but rofecoxib was withdrawn due to cardiovascular side effects. Although this selective COX-2 inhibitor, like diet, may alter the fatty acid and eicosanoid pattern, data on the potential alteration in tissues after use, are scarce. The aims were to study if rofecoxib might influence the fatty acid distribution in serum phospholipids and duodenal lesions, mRNA for COX-1 and COX-2 in leucocytes and duodenal lesions, and finally plasma levels of PGE(2) in a randomized, double-blind, placebo controlled study (n = 38). Significant reductions were found for essential fatty acid index both in serum phospholipids (P = 0.01, 95% CI = -0.9; -0.1), and in duodenal lesions (P = 0.04, 95 CI % = -0.9; -0.1) after treatment. No treatment effects were found on the COX mRNA expression, or in the plasma PGE(2) levels. Dietary AA/EPA ratio was inversely associated with all the indicators of EFA status (all P < 0.01). These findings suggest that the effects of COX chemoprevention should be further investigated in FAP and that dietary needs should be included in the treatment of FAP.

Neoplastic and preneoplastic lesions induced by melamine in rat urothelium are modulated by dietary polyunsaturated fatty acids

The modulatory effects of polyunsaturated fatty acids (PUFA) on urinary tract tumorigenesis of 275 Wistar rats were evaluated by treating animals with the tumorigenic agent melamine. Rats were fed with formulae containing 6% of 4 varieties of fats: fish oil enriched in n-3 PUFA (FO), corn oil enriched in n-6 (CO), olein containing mainly n-9 oleic acid (O), and 98% stearic acid (SA), the latter two being essential (EFA)-deficient inducers. Two commercially fed control groups with (CM) and without (C) melamine were used. Animals were autopsied at 22-25 and at 36-40 weeks. Hepatic fatty acids showed that O and SA groups were EFA-deficient. Simple well differentiated hyperplasias were significantly higher in the FO lot, whereas dysplasia was increased in the CO, O and SA lots. Most of the animals fed for 36-40 weeks with the three latter formulae developed the more severe lesions. Increased urothelial proliferation was more frequent in EFA-deficient rats. The apoptosis/mitosis ratio was higher in O, SA and CO fed animals with respect to FO and chow ones. Results show that dietary PUFA modulate differentially both normal and pre-neoplastic urothelial proliferation induced by melamine. FO, rich in n-3 fatty acids, showed a strong protective effect.

Effects of eicosatrienoic acid (20:3 n-9, Mead's acid) on some promalignant-related properties of three human cancer cell lines

The essential fatty acid deficiency (EFAD) is a metabolic condition related to cancer development. We studied the effect of eicosapentaenoic acid (EPA, 20:5 n-3) and eicosatrienoic acid (ETA, 20:3 n-9), an essential fatty acid (EFA) and non-EFA respectively, on tumour cells parameters linked to tumour progression and metastases. Human tumour cell lines (T-24 from urothelium, MCF-7 from breast and HRT-18 from colon) were used. EPA showed an anti-proliferative effect on the three lines. ETA showed the following effects: in T-24, the lipid peroxidation was decreased and E-cadherin was undetectable; in MCF-7, increased E-cadherin expression enhanced the lipid peroxidation and decreased cell proliferation; on HRT-18, the E-cadherin expression and lipid peroxidation diminished, whereas cell proliferation was increased. In conclusion, EFA (20:5 n-3) exhibited beneficial effects, whereas unusual ETA showed an opposite effect on some tumour parameters. The possible riskiness of EFA-deprivation, along with the potential of EFA as natural nutrapeutic products for human tumour prevention and treatment, makes EFA worthy of further consideration.

Conjugated linoleic acid (CLA) versus saturated fats/cholesterol: their proportion in fatty and lean meats may affect the risk of developing colon cancer

In spite of the considerable amount of experimental, clinical and epidemiological research about the consumption of red meat, total fats, saturated/unsaturated fatty acids and cholesterol with regard to the risk of developing colorectal cancer (CRC), the issue remains controversial. The general belief is a reduction of red meat intake, and subsequent nutritional advice usually strongly recommends this. Paradoxically, beef together with whole milk and dairy derivatives, are almost the only sources for conjugated linoleic acid (CLAs) family. Furthermore CLAs are the only natural fatty acids accepted by the National Academy of Sciences of USA as exhibiting consistent antitumor properties at levels as low as 0.25-1.0 per cent of total fats. Beside CLA, other polyunsaturated fatty acids (PUFA) belonging to the essential fatty acid (EFA) n-3 family, whose main source are fish and seafood, are generally believed to be antipromoters for several cancers. The purpose of this work is to critically analyze the epidemiological and experimental evidence by tentatively assuming that the reciprocal proportions of saturated fats (SA) plus cholesterol (CH) versus CLAs levels in fatty or lean beef may play an antagonistic role underlying the contradictory effects reported for red meats consumption and CRC risk. Recent results about meat intake and risk for CRC in Argentina have shown an unexpected dual behaviour related to the type of meats. Fatty meat derivatives, such as cold cuts and sausages, mainly prepared from fatty beef (up to 37% fat) were associated with higher risk, whereas high consumption of lean beef (< 15% fat) behaved as a protective dietary habit. CLA is located in the interstitial, non-visible, fat evenly distributed along muscle fibres as well as in subcutaneous depots. Visible fat may be easily discarded during the meal, whereas interstitial fats will be eaten. The remaining intramuscular fat in lean meats range from 25 to 50 g/Kg (2.5 to 5%). The proportion of CLA/SA+CH for lean beef eaters is 0.09 and the fatty meats 0.007 (g/100 g). As a consequence, the beneficial effects of minor amounts of CLA may be relatively enhanced in lean meat compared to fatty meat sub-products which contain a substantial amount of saturated fatty acids and cholesterol, as in cold cuts and cow viscera.

Characterization of meat consumption and risk of colorectal cancer in Cordoba, Argentina

BACKGROUND

The Argentinean food pattern, rich in beef and fats and poor in fibers, may be related to an risk of increased colorectal cancer (CRC). To examine the relation between CRC risk and meat type, we carried out a case-control study in Córdoba, Argentina.

METHODS

We interviewed 287 patients with colorectal adenocarcinomas and 566 control subjects admitted to the largest hospitals in greater Córdoba. Dietary habits were assessed by a food-frequency questionnaire, and different meat types were evaluated. Regression analyses determined the contribution of meat to total energy and macronutrients. Unconditional multiple logistic regression was performed to calculate odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

Median intake of all meats, predominantly bovine, was high, reaching almost 300 g/d in men. Meats provided approximately 50% of total energy intake and 64% to 67% of total protein. Patients obtained significantly more cholesterol and total lipids from meats than did controls. Consumption of total meat, red meat, and other types of meat were not related to increased risk of CRC. However, an increased risk of CRC was found for those consuming relatively large amounts of cold cuts and sausages (OR, 1.47; CI, 1.02-2.15) and bovine viscera (OR, 1.73; CI, 1.18-2.54). Lean beef was associated with a decreased risk of CRC at the second (OR, 0.64; CI, 0.43-0.94) and third (OR, 0.67; CI, 0.40-0.97) tertiles.

CONCLUSIONS

Red meat produced a different pattern of risk according to its fat content. Further studies should assess the possible role of cooking meat and other non-nutritional components.

Dietary polyunsatured fatty acids (PUFA) differentially modulate melamine-induced preneoplastic urothelial proliferation and apoptosis in mice

A number of experimental and epidemiological studies indicate that dietary polyunsaturated fatty acids (PUFA) play a modulatory role in the development of several cancers. However, literature on the importance of dietary PUFA in urinary-tract tumourigenesis is scarce, and even contradictory. Therefore, our purpose was to evaluate comparatively, several urothelial cellular parameters linked to neoplasia when 180 BALB/c mice were initiated with the tumourigenic agent melamine and fed with two amounts of different PUFA. In experiment 1, mice were fed with 6% of fish oil (enriched in n-3 PUFA, FO), corn oil (enriched in n-6, CO) and olein (enriched in n-9, an EFA deficiency inducer) formulae plus two chow-fed control lots with (CM) and without (C) melamine treatment. In experiment 2, each of the three varieties of PUFA were offered at 10%. Following 18-22 weeks of melamine treatment, animals were autopsied. The liver fatty acid profile showed a close correlation with the dietary sources, exhibiting in the O group macroscopic and biochemical EFA-deficient (EFAD) characteristics. The frequency of simple urothelial hyperplasias (H) and dysplasia/carcinoma in situ (D/CIS) was significantly lower in the FO group, whereas both types of lesions increased in the CO and O groups, compared to the C and CM mice. Increased proliferation and abnormal luminal localized mitosis were more frequently recorded in EFAD mice, whereas abnormal apoptotic/mitosis ratio increased in both olein- and corn-oil-fed animals. This study shows that dietary PUFA modulate differentially normal and pre-neoplastic proliferation when induced by the tumorigenic agent melamine. Fish oil, rich in n-3 fatty acids, exhibits a clear antipromoting activity, whereas the role of n-6 and n-9 PUFA derivatives needs further research.

Effects of dietary fat on benz-a-pyrene-induced forestomach tumorigenesis in mice chronically exposed to arsenic

The modulating effect of As (As2O3) in drinking water plus dietary fatty acids on benzo-a-pyrene (BP) induced forestomach tumorigenesis was assayed in mice fed with corn oil (CO), Olein (O), palmstearin (PS) and cod liver oil (CLO) enriched formulae, and a mixed-fat (S-stock) diet during 28 weeks. Neither pre-or neoplastic lesions were recorded in esophagus or forestomach of mice treated with As alone. CLO diet showed a protective effect. Indeed, multiple epidermal hyperplasia were significantly reduced compared to S group and a reduction in papillomas multiplicity with respect to S, CO and O groups was also observed. Mice fed on PS formula showed minor papillomas per mouse with respect to CO and O. These results indicate that As plus BP did not exhibit any synergistic effect on the development of epidermoid tumor lesions, whereas CLO diet exerted antipromoting activity . In spite of their common essential fatty acid deficiency (EFAD) condition, PS and O lots showed contradictory results. Hence, the dietary enrichment in 18:1 n-9 (O diet) per se, and not the EFAD state, may play a deleterious role. Corn diet showed no promoting activity on the epidermoid tumor development in this model.

N-3, n-6 and n-9 dietary fatty acids modulate the growth parameters of murine salivary gland tumors induced by dimethylbenzanthracene

Variations in dietary fatty acid composition influence the biological behaviour of certain tumours. Diets enriched with oleic acid (18:1 n-9) seem to promote tumour progression on several lines due perhaps to the development of essential fatty acid deficiency (EFAD), whereas n-3 fatty acids have a protective effect. Since the role played by lipids on salivary gland tumorigenesis has not yet been studied, an experimental model is presented. BALB/c mice were fed on four different diets: control, corn oil, fish oil and olein groups. Salivary gland adenocarcinomas were chemically induced by using 9,10-dimethyl-1,2-benzanthracene. Animals were sacrificed at the 20th post-injection week and several tumour parameters were analysed. Linoleic acid showed no promoting activity. Tumour size was larger in the olein group than in fish oil fed mice, indicating that the oleic acid, linked to the induced EFAD condition, has a protumorigenic activity whereas n-3 polyunsaturated fatty acids appear to exert a protective effect.

Differential effects of dietary Oenothera, Zizyphus mistol, and corn oils, and essential fatty acid deficiency on the progression of a murine mammary gland adenocarcinoma

The modulating effect of dietary enrichment in mistol seed oil (MO) containing 25% of alpha-linolenic acid (ALA), evening primrose oil (EPO) enriched in gamma-linolenic acid (GLA) and corn oil (CO) as sources of omega-6 and omega-9 fatty acids on the growth parameters of one transplantable mammary tumor were compared. Mice fed on different lipid formulae were inoculated with a mammary gland adenocarcinoma and different growth development tumor parameters were recorded. Results showed that corn oil feeding slowed down most of the tumor growth parameters, as did the EPO diet. MO also showed antitumor activity. Olein feeding, which induces an essential fatty acid deficiency (EFAD), increased the incidence and the multiplicity of metastases when compared with the controls. It may be concluded that a diet enriched in omega-6 fatty acids did not behave as a tumor promoter in this mammary gland tumor model. The antitumor activities of EPO and MO are corroborated in present experiments, suggesting that both oils may be of value in nutritional approaches of mammary gland tumor therapies. In addition, present data add further experimental proof about the proposed protumorigenic proneness induced by the EFAD state.

Differential modulation by dietary n-6 or n-9 unsaturated fatty acids on the development of two murine mammary gland tumors having different metastatic capabilities

It is widely known that dietary lipids can modify the ability of different cancers to grow up and metastasize, especially mammary gland tumors. However, it is still unclear whether n-6 fatty acids behave as tumor promoters in this gland cell population. The effect of different nutritional polyunsaturated fatty acids (PUFAs) on tumor growth parameters of two transplantable murine mammary gland adenocarcinomas of low and high metastatic ability was tested on hosts fed diets with corn oil (CO) rich in 18:2n-6, evening primrose oil (EPO) containing 18:3n-6 (GLA) and a third formula supplemented with olein (O) 18:1n-9, which induces an essential fatty acid deficiency (EFAD). Tumor growth parameters were not adversely affected in the corn oil group with respect to stock-fed controls. Furthermore, metastatic spreading diminished in this group. EPO showed a moderate antitumor activity whereas the n-9-enriched diet showed no clear-cut effects. In both mammary gland tumors, n-6 fatty acid-rich lipids formulae, containing GLA and linoleic acid, were not tumor promoters. On the contrary, both exhibited anticancer activity.

Is the risk of urinary tract tumorigenesis enhanced by a marginal chronic essential fatty acid deficiency (EFAD)?

A considerable amount of experimental, clinical and epidemiological data indicate that dietary fats play a role in urinary tract tumorigenesis. In rodents, chronic essential fatty acid (EFA) deficiency seems to induce both urolithiasis and transitional hyperplasias, followed by a tendency for tumorigenesis of the urinary passages. High intake of saturated fats or non-EFAs, conditions that may induce EFA deficiency (EFAD) increase the risk of bladder cancer in case-control studies. In other cell populations, EFAs are beneficial as preventive and therapeutic nutrients for the treatment of cancer. Thus, it is reasonable to assume that abnormal metabolism and/or nutritional deprivation of EFA, by inducing a chronic or a subclinical EFA deficiency, may enhance the risk of urothelial tumorigenesis.