Specific versus non-specific effects of dietary fat on carcinogenesis

Sex hormone-binding globulin and its critical role in prostate cancer: A comprehensive review

Prostate cancer (PC) is a common and widespread cancer that affects men globally. A complicated interaction of hormonal variables influences its development. Sex hormone-binding globulin (SHBG) is a crucial element in controlling the availability of sex hormones, especially androgens, which have a notable impact on the development and progression of PC. SHBG controls the levels of free, active androgens in the body, which helps regulate androgen-dependent processes associated with PC. The equilibrium between SHBG and androgens plays a critical role in maintaining the stability of the prostate. When this balance is disrupted, it is associated with the development and advancement of PC. The processes responsible for SHBG's role in PC are complex and have multiple aspects. SHBG primarily binds to androgens, preventing them from interacting with androgen receptors (ARs) in prostate cells. It reduces the activation of androgen signaling pathways essential for tumor development and survival. In addition, SHBG can directly affect prostate cells by interacting with specific receptors on the cell surface. This review thoroughly examines the role of SHBG in PC, including its physiological activities, methods of action, and clinical consequences.

Extra-Virgin Olive Oil and Its Minor Compounds Influence Apoptosis in Experimental Mammary Tumors and Human Breast Cancer Cell Lines

Simple Summary

Breast cancer is a disease influenced by dietetic factors, such as the type and amount of lipids in a diet. In this work, we aimed to elucidate the different effects of two high-fat diets on the histopathological and molecular characteristics of mammary tumors in an experimental model. Animals fed with a diet high in extra-virgin olive oil (EVOO), compared to those fed with a diet high in seed oil, developed tumors with less aggressiveness and proliferation. Tumor molecular analyses of several cell death pathways also suggested an effect of EVOO in this process. In vitro experiments indicated the role of EVOO minor compounds on the effects of this oil. Obtaining insights into the influence and the mechanisms of action of dietary compounds are necessary to understand the relevance that dietetic habits from childhood may have on health and the risk of disease.

Abstract

Breast cancer is the most common malignancy among women worldwide. Modifiable factors such as nutrition have a role in its etiology. In experimental tumors, we have observed the differential influence of high-fat diets in metabolic pathways, suggesting a different balance in proliferation/apoptosis. In this work, we analyzed the effects of a diet high in n-6 polyunsaturated fatty acids (PUFA) and a diet high in extra-virgin olive oil (EVOO) on the histopathological features and different cell death pathways in the dimethylbenz(a)anthracene-induced breast cancer model. The diet high in n-6 PUFA had a stimulating effect on the morphological aggressiveness of tumors and their proliferation, while no significant differences were found in groups fed the EVOO-enriched diet in comparison to a low-fat control group. The high-EVOO diet induced modifications in proteins involved in several cell death pathways. In vitro analysis in different human breast cancer cell lines showed an effect of EVOO minor compounds (especially hydroxytyrosol), but not of fatty acids, decreasing viability while increasing apoptosis. The results suggest an effect of dietary lipids on tumor molecular contexts that result in the modulation of different pathways, highlighting the importance of apoptosis in the interplay of survival processes and how dietary habits may have an impact on breast cancer risk.

Influence of Olive Oil and Its Components on Breast Cancer: Molecular Mechanisms

Breast cancer is the most frequent malignant neoplasia and a leading cause of mortality in women worldwide. The Mediterranean diet has been proposed as a healthy dietary pattern with protective effects in several chronic diseases, including breast cancer. This diet is characterized by the consumption of abundant plant foods and olive oil as the principal source of fat, which is considered one of the main components with potential antioxidant, anti-inflammatory and anticancer effects. Extra-virgin olive oil (EVOO) has several bioactive compounds, mainly including monounsaturated fatty acids, triterpenes and polyphenols, such as phenolic alcohols (e.g., hydroxytyrosol), secoiridoids (e.g., oleuropein and oleocanthal), lignans (e.g., pinoresinol) or flavonoids (e.g., luteolin). While epidemiological evidence is still limited, experimental in vivo and in vitro data have shown a protective effect of this oil and its compounds on mammary carcinogenesis. Such effects account through complex and multiple mechanisms, including changes in epigenetics, transcriptome and protein expression that modulate several signaling pathways. Molecular targets of EVOO compounds have a role in the acquisition of cancer hallmarks. Although further research is needed to elucidate their beneficial effects on human prevention and progression of the disease, evidence points to EVOO in the context of the Mediterranean diet as a heathy choice, while EVOO components may be promising adjuvants in anticancer strategies.

PPARδ and its ligand erucic acid may act anti-tumoral, neuroprotective, and myelin protective in neuroblastoma, glioblastoma, and Parkinson's disease

In this review study, we focus on potential benefits of the transcription factor PPARδ and its ligand erucic acid (EA) in management of neuroectodermal tumors and Parkinson's Disease. PPARδ is a nuclear receptor and transcription factor that induces myelination, promotes oligodendroglial and neuronal differentiation, and possess anti-neuroinflammatory properties. While both pro-tumorigenic and anti-tumorigenic effects have been described for PPARδ, we propose that PPARδ may perform a predominantly anticancer role in tumors originating from the neuroectoderm. PPARδ ligand-activation via oleic acid and GW501516, or overexpression of PPARδ, elicits profound antitumor actions in neuroblastoma and melanoma. In glioblastomas, there is evidence indicating a differentiation failure of O2A (oligodendroglial-astrocytic biprogenitor) cells and it has been shown that EA reduced DNA synthesis in C6 rat glioblastoma spheroid cultures in clinically achievable concentrations. EA is a ω9 fatty acid which is being used in the treatment of adrenoleukodystrophy. EA is widely consumed in Asian countries via ingestion of cruciferous vegetables including mustard and rapeseed oil. EA also exerts antioxidant and anti-inflammatory activities. Recent studies of Parkinson's Disease (PD) have implicated demyelination, white matter pathology, oligodendroglial injury, and neural inflammation in the underlying pathophysiology. In the rotenone PD model in rats, PPARδ ligand GW501516 saves dopaminergic neurons during injury induced by chemical toxins and improves behavioral functioning in PD via alleviation of endoplasmic reticulum stress. PPARδ agonists also reduce the NLRP3 inflammasome-associated neural inflammation in the MPTP PD model in mice. Herein, we propose that PPARδ and its ligand EA highly deserve to be studied in animal models of neuroblastoma, glioblastoma, and PD.

The Role of Dietary Extra Virgin Olive Oil and Corn Oil on the Alteration of Epigenetic Patterns in the Rat DMBA-Induced Breast Cancer Model

Disruption of epigenetic patterns is a major change occurring in all types of cancers. Such alterations are characterized by global DNA hypomethylation, gene-promoter hypermethylation and aberrant histone modifications, and may be modified by environment. Nutritional factors, and especially dietary lipids, have a role in the etiology of breast cancer. Thus, we aimed to analyze the influence of different high fat diets on DNA methylation and histone modifications in the rat dimethylbenz(a)anthracene (DMBA)-induced breast cancer model. Female Sprague-Dawley rats were fed a low-fat, a high corn-oil or a high extra-virgin olive oil (EVOO) diet from weaning or from induction with DMBA. In mammary glands and tumors we analyzed global and gene specific (RASSF1A, TIMP3) DNA methylation by LUMA and bisulfite pyrosequencing assays, respectively. We also determined gene expression and enzymatic activity of DNA methyltransferases (DNMT1, DNMT3a and DNMT3b) and evaluated changes in histone modifications (H3K4me2, H3K27me3, H4K20me3 and H4K16ac) by western-blot. Our results showed variations along time in the global DNA methylation of the mammary gland displaying decreases at puberty and with aging. The olive oil-enriched diet, on the one hand, increased the levels of global DNA methylation in mammary gland and tumor, and on the other, changed histone modifications patterns. The corn oil-enriched diet increased DNA methyltransferase activity in both tissues, resulting in an increase in the promoter methylation of the tumor suppressor genes RASSF1A and TIMP3. These results suggest a differential effect of the high fat diets on epigenetic patterns with a relevant role in the neoplastic transformation, which could be one of the mechanisms of their differential promoter effect, clearly stimulating for the high corn-oil diet and with a weaker influence for the high EVOO diet, on breast cancer progression.

Localization and upregulation of survivin in cancer health disparities: a clinical perspective

Survivin is one of the most important members of the inhibitors of apoptosis protein family, as it is expressed in most human cancers but is absent in normal, differentiated tissues. Lending to its importance, survivin has proven associations with apoptosis and cell cycle control, and has more recently been shown to modulate the tumor microenvironment and immune evasion as a result of its extracellular localization. Upregulation of survivin has been found in many cancers including breast, prostate, pancreatic, and hematological malignancies, and it may prove to be associated with the advanced presentation, poorer prognosis, and lower survival rates observed in ethnically diverse populations.

Diets high in corn oil or extra-virgin olive oil differentially modify the gene expression profile of the mammary gland and influence experimental breast cancer susceptibility

PURPOSE

Nutritional factors, especially dietary lipids, may have a role in the etiology of breast cancer. We aimed to analyze the effects of high-fat diets on the susceptibility of the mammary gland to experimental malignant transformation.

METHODS

Female Sprague-Dawley rats were fed a low-fat, high-corn-oil, or high-extra-virgin olive oil (EVOO) diet from weaning or from induction. Animals were induced with 7,12-dimethylbenz[a]anthracene at 53 days and euthanized at 36, 51, 100 and 246 days. Gene expression profiles of mammary glands were determined by microarrays. Further molecular analyses were performed by real-time PCR, TUNEL and immunohistochemistry. Carcinogenesis parameters were determined at 105 and 246 days.

RESULTS

High-corn-oil diet increased body weight and mass when administered from weaning. The EVOO diet did not modify these parameters and increased the hepatic expression of UCP2, suggesting a decrease in intake/expenditure balance. Both diets differentially modified the gene expression profile of the mammary gland, especially after short dietary intervention. Corn oil down-regulated the expression of genes related to immune system and apoptosis, whereas EVOO modified the expression of metabolism genes. Further analysis suggested an increase in proliferation and lower apoptosis in the mammary glands by effect of the high-corn-oil diet, which may be one of the mechanisms of its clear stimulating effect on carcinogenesis.

CONCLUSIONS

The high-corn-oil diet strongly stimulates mammary tumorigenesis in association with modifications in the expression profile and an increased proliferation/apoptosis balance of the mammary gland.

Olive oil and other dietary lipids in breast cancer

Breast cancer is the most frequent malignant neoplasia among women worldwide. In addition to genetic and endocrine factors, the environment, and specifically nutritional factors, plays a key role in its aetiology. Epidemiological and in particular experimental studies have shown the link between dietary fat and breast cancer. Abundant data have attributed a potentially chemopreventive effect for extra-virgin olive oil (EVOO), the main source of fat in the Mediterranean diet, which is associated with low incidence and mortality rates from chronic diseases such as breast cancer. We have demonstrated the differential modulatory effect of dietary lipids on mammary carcinogenesis, mainly in studies developed in an experimental model. Thus, diets high in n-6 polyunsaturated fatty acids (PUFA) have a clear stimulating influence, whereas EVOO diets mainly have a negative modulatory effect on breast cancer development. The specific mechanisms involved are not fully understood, but nowadays, it is widely accepted that they are numerous and complex. Our group has contributed to improving the knowledge of these mechanisms by demonstrating the influence of dietary lipids on the structure and function of cell membranes, the modulation of cell-signalling transduction pathways, the regulation of gene expression and growth and sexual maturity.

Trans fatty acid intake is associated with increased risk and n3 fatty acid intake with reduced risk of non-hodgkin lymphoma

We evaluated the association of dietary fat and protein intake with risk of non-Hodgkin lymphoma (NHL) in a clinic-based study in 603 cases (including 218 chronic lymphocytic leukemia/small lymphocytic lymphoma, 146 follicular lymphoma, and 105 diffuse large B-cell lymphoma) and 1007 frequency-matched controls. Usual diet was assessed with a 128-item food-frequency questionnaire. Unconditional logistic regression was used to estimate ORs and 95% CIs, and polytomous logistic regression was used to assess subtype-specific risks. trans Fatty acid (TFA) intake was positively associated with NHL risk [OR = 1.60 for highest vs. lowest quartile (95% CI = 1.18, 2.15); P-trend = 0.0014], n3 (ω3) fatty acid intake was inversely associated with risk [OR = 0.48 (95% CI = 0.35, 0.65); P-trend < 0.0001], and there was no association with total, animal, plant-based, or saturated fat intake. When examining intake of specific foods, processed meat [OR = 1.37 (95% CI = 1.02, 1.83); P-trend = 0.03], milk containing any fat [OR = 1.47 (95% CI = 1.16, 1.88); P-trend = 0.0025], and high-fat ice cream [OR = 4.03 (95% CI = 2.80, 5.80); P-trend < 0.0001], intakes were positively associated with risk, whereas intakes of fresh fish and total seafood [OR = 0.61 (95% CI = 0.46, 0.80); P-trend = 0.0025] were inversely associated with risk. Overall, there was little evidence for NHL subtype-specific heterogeneity. In conclusion, diets high in TFAs, processed meats, and higher fat dairy products were positively associated with NHL risk, whereas diets high in n3 fatty acids and total seafood were inversely associated with risk.

Olive oil, an essential component of the Mediterranean diet, and breast cancer

Objective

The Mediterranean diet has been related to a lower risk of some chronic diseases, including cancer. We aim to gain insight into the effects of the main source of fat of this diet on breast cancer, the most common type of malignancy in women.

Design

Data from sixteen experimental series analysing the effects of dietary lipids on mammary carcinogenesis in an animal model, in the context of the international literature on the Mediterranean diet, olive oil and breast cancer risk.

Setting

Experimental and human data on the effects of olive oil and Mediterranean diet on breast cancer.

Subjects

An animal model of induced breast cancer and other human and experimental studies in the literature.

Results

Diets rich in extra virgin olive oil (EVOO) exert a negative modulatory effect on experimental breast cancer to a weak promoting effect, much lower than that obtained with a high-corn oil diet. EVOO confers to the mammary adenocarcinomas a clinical behaviour and morphological features compatible with low tumour aggressiveness. This differential effect, in relation to other dietary lipids, may be related to a lower effect on body weight and sexual maturation. In addition, EVOO induced different molecular changes in tumours, such as in the composition of cell membranes, activity of signalling proteins and gene expression. All these modifications could induce lower proliferation, higher apoptosis and lower DNA damage. These results, together with the favourable effect of olive oil reported in the literature when it is consumed in moderate quantities, suggest a beneficial influence of EVOO on breast cancer risk.

Conclusions

Consumption of EVOO in moderate quantities and throughout the lifetime appears to be a healthy choice and may favourably influence breast cancer risk.

Dietary fat-influenced development of colon neoplasia in Apc Min mice exposed to benzo(a)pyrene

Colorectal cancer, responsible for 50,000 deaths per year, is a contributing factor for considerable mortalities in the United States. Consumption of well-done red meat and saturated fats rich in polycyclic aromatic hydrocarbons may be one of the causative factors for sporadic colon cancer. The objective of this study was to investigate whether the formation of colon tumors in adult Apc(Min) mice was influenced by the ingestion of different types of fat containing benzo(a)pyrene [B(a)P], a polycyclic aromatic hydrocarbon compound. Treatment consisted of 50 and 100 microg B(a)P/kg body weight dissolved in peanut or coconut oil (representatives of unsaturated and saturated fats, respectively) administered daily to six-week-old male Apc(Min) mice via oral gavage for sixty days. At the end of exposure, mice were sacrificed; jejunum and colons were retrieved and preserved in 10% formalin for observation for gross pathological changes. An increased prevalence of adenomas in colons of mice that ingested B(a)P through saturated dietary fat compared to unsaturated fat and controls (p < .05) was noticed. Interestingly, we also observed adenomas with high-grade dysplasia in the B(a)P + saturated fat group, and these incidences were frequent at the 100 microg/kg B(a)P dose. On the other hand, the B(a)P-alone and unsaturated-fat groups did not show significant differences in the numbers of adenomas and invasive tumors in the both jejunum and the colon. Our studies established that dietary fat, especially saturated fat, potentiates the development of colon tumors caused by B(a)P in the Apc(Min) mouse.

Dietary fat intake and risk of prostate cancer in the European Prospective Investigation into Cancer and Nutrition

BACKGROUND

Findings from early observational studies have suggested that the intake of dietary fat might be a contributing factor in the etiology of prostate cancer. However, the results from more recent prospective studies do not support this hypothesis, and the possible association between different food sources of fat and prostate cancer risk also remains unclear.

OBJECTIVE

The objectives were to assess whether intakes of dietary fat, subtypes of fat, and fat from animal products were associated with prostate cancer risk.

DESIGN

This was a multicenter prospective study of 142,520 men in the European Prospective Investigation into Cancer and Nutrition (EPIC). Dietary fat intake was estimated with the use of country-specific validated food questionnaires. The association between dietary fat and risk of prostate cancer was assessed by using Cox regression, stratified by recruitment center and adjusted for height, weight, smoking, education, marital status, and energy intake.

RESULTS

After a median follow-up time of 8.7 y, prostate cancer was diagnosed in 2727 men. There was no significant association between dietary fat (total, saturated, monounsaturated, and polyunsaturated fat and the ratio of polyunsaturated to saturated fat) and risk of prostate cancer. The hazard ratio for prostate cancer for the highest versus the lowest quintile of total fat intake was 0.96 (95% CI: 0.84, 1.09; P for trend = 0.155). There were no significant associations between prostate cancer risk and fat from red meat, dairy products, and fish.

CONCLUSION

The results from this large multicenter study suggest that there is no association between dietary fat and prostate cancer risk.

The effects of dietary lipids on adrenergically-stimulated lipolysis in perinodal adipose tissue following prolonged activation of a single lymph node

The effects of feeding beef suet (mostly saturated and monoenoic fatty acids), sunflower oil (rich inn-6 fatty acids) and fish oil (rich inn-3 fatty acids) on the response of mesenteric, omental, popliteal and perirenal adipocytes to experimentally-induced local inflammation were studied in adult guinea pigs. After 6 weeks on the experimental diets, the animals were fed standard chow, and lipopolysaccharide was injected unilaterally daily for 4 d to induce swelling of one popliteal lymph node. Basal lipolysis in the perinodal adipocytes of all depots studied was higher in the sunflower oil-fed animals than in the controls fed on standard chow, and lower in those fed on suet or fish oil. Dietary lipids altered rates of lipolysis during incubation with 10-5M noradrenaline in all samples studied from the locally-activated popliteal depot, but only in adipocytes within 5 mm of a large lymph node in the other depots. The fish-oil diet attenuated the spread of increased lipolysis within the locally-activated popliteal adipose tissue, and from this depot to other node-containing depots. These experiments show thatn-6 polyunsaturated fatty acids promote andn-3 fatty acids suppress the spread of immune activation to adipocytes within and between depots, and alter the sensitivity of perinodal adipocytes to noradrenaline. Dietary effects are reduced or absent in adipocytes in sites remote from lymph nodes, and thus such samples do not adequately represent processes in perinodal adipose tissue. These results are consistent with the hypothesis that perinodal adipocytes interact with adjacent lymphoid cells during immune responses.

A 24-month dietary carcinogenicity study of DAG (diacylglycerol) in rats

Toxicologic and carcinogenic effects of DAG (diacylglycerol) oil, administered in diet for 24 months to Crl:CD((R))(SD)-IGS BR rats, were evaluated using diet-restricted and ad libitum-fed groups. All dietary fat (consistently 5.5%) was provided by DAG and/or the control article, TG (triacylglycerol) oil. Dietary concentrations (% DAG/% TG) were 0%/5.5%, 1%/4.5%, 2.75%/2.75% and 5.5%/0%. Separate groups were fed the 0%/5.5% and 5.5%/0% diets ad libitum. Another group received the standard rodent diet (fat content 4.5%) on the restricted feeding regimen. Clinical condition, ophthalmic findings, palpable mass occurrence, body composition, clinical pathology parameters and incidence of neoplastic lesions were unaffected by DAG in comparison to TG. Groups fed the 5.5% (DAG and/or TG) fat diet when compared to the 4.5% fat diet group displayed lower survival, higher body weights, organ weights, percent body fat, higher fat-related serum chemistry parameters, incidence of microscopic changes in the heart, kidneys, liver, bone marrow, spleen, and incidences of pituitary and mammary gland neoplasms. Parameters more affected in all the ad libitum groups than in the restricted diet groups (regardless of test article) fed the same diet included survival, body weights, body fat, fat-related serum chemistry parameters, and incidences of heart, kidney and liver microscopic changes. However, the DAG and TG ad libitum-fed groups were not different from one another. Thus, DAG-treated animals had no higher risk of carcinogenic effects than rats fed on similar feeding regimens with a diet in which all dietary fat came from TG.

BMI and waist circumference as predictors of lifetime colon cancer risk in Framingham Study adults

BACKGROUND

It is unclear whether the increased risk of colon cancer associated with obesity differs for men and women, by distribution of body fat, or by location of the tumor. The primary goal of this study was to address these questions.

METHODS

Eligible subjects from the Framingham Study cohort were classified according to body mass index (BMI) and waist size during two age periods: 30-54 y (n=3764) and 55-79 y (n=3802). All eligible men and women were cancer-free at baseline and had complete information on the following potential confounders: age, sex, education, height, activity, smoking, and alcohol. There were 157 incident lifetime cases of colon cancer among those followed beginning at 30-54 y of age and 149 lifetime cases among those whose follow up began at 55-79 y. Subjects were stratified further by gender, activity, and tumor location. The Cox Proportional Hazards Models were used to adjust for possible confounding by the above-described factors.

RESULTS

A BMI >/=30 led to a 50% increased risk (95% CI: 0.92-2.5) of colon cancer among middle-aged (30-54 y) and a 2.4-fold increased risk (95% CI: 1.5-3.9) among older (55-79 y) adults. The BMI effect was stronger for men than for women and for cases occurring in the proximal colon. These adverse effects generally diminished when waist was added to the multivariable models. A larger waist size (>/=99.1 cm (39 in) and 101.6 cm (40 in) for women and men, respectively) was associated with a two-fold increased risk of colon cancer; this risk increased linearly with increasing waist size and was evident for both proximal and distal colon cancer. There was no attenuation of these effects when BMI was added to the multivariable models. A larger waist had a particularly adverse effect among sedentary subjects (relative risk (RR)=4.4 for middle-aged adults; RR=3.0 for older adults).

CONCLUSION

These findings suggest that waist circumference is a stronger predictor of colon cancer risk than is BMI, and that central obesity is responsible for an increased risk of cancer of both the proximal and distal colon.

Nutritional-pharmacological combinations--a novel approach to reducing colon cancer incidence

BACKGROUND

Recent studies have suggested that n-9 fatty acids in olive oil prevent colon carcinogenesis while n-6 PUFA seems to activate this process.

AIMS

To evaluate the effects of nutritional-pharmacological combinations made up of olive or soy oil-based diets and the drug sulindac, on colon cancer incidence in a chemically induced (1,2-dimethylhydrazine, DMH) rat cancer model.

METHODS

Male rats were assigned to two different dietary regimes based on a standard murine defined diet (AIN-76A) containing either a low (4%) or high (15 %) concentration of olive or soy oil. Some groups also received sulindac in their food (80 mg/kg food) starting from the ninth week following the first DMH or vehicle administration.

RESULTS

Oleic and linoleic acid reached higher levels in plasma and liver lipids when rats were fed high concentrations of olive or soy oil, respectively. Rats fed a low or high soy oil-based diet showed no significant difference in the number of aberrant crypt foci (ACF) in proximal or distal colon specimens. In contrast, rats fed a higher olive oil-based diet developed a significantly lower number of ACF than rats fed a low concentration of olive oil. Addition of sulindac reduced the number of ACF in rats fed the 4%, but not the 15%, soy oil diet. In contrast, the effect of sulindac was significant when combined with both the low and high concentrations of olive oil. High soy oil-based diet or DMH treatment upregulated colon expression of Bcl-2, but not that of cyclooxygenase-2 (COX-2). In contrast, olive oil dose-dependently downregulated the expression of both Bcl-2 and COX-2 in colonic mucosa and also abrogated the upregulation of Bcl-2 by DMH. Olive oil/sulindac combinations were effective in downregulating colonic mucosa Bcl-2 expression (with the 4% oil diet) and COX-2 expression (with the 15% oil diet). These effects were not observed in rats fed the soy oil/sulindac combinations. Caspase-3 activity in colonic mucosa was unaffected by soy oil or soy oil/sulindac combinations. The addition of olive oil, on the other hand, significantly enhanced colonic caspase-3 activity.

CONCLUSIONS

Diets containing high levels of olive oil exert a significant protective effect from tumor development that is additive with the inhibitory effect of sulindac. These inhibitory effects are mediated by regulating the expression and activity of key proteins involved in prostaglandin-biosynthesis and apoptosis-induction pathways. It may be concluded that appropriate dietary-pharmacological combination can improve anti-tumor efficacy over either dietary or pharmacological intervention alone.

A low-fat diet and/or strenuous exercise alters the IGF axis in vivo and reduces prostate tumor cell growth in vitro

BACKGROUND

Prostate cancer is the most common solid-tumor cancer in US males but is rare in Asian males. When Asian men adopt the US lifestyle, clinical prostate cancer increases greatly. Epidemiological data from men in the US indicate that regular activity may reduce the risk for prostate cancer.

METHODS

Serum was obtained from three groups of similar-aged men, Control, Diet and Exercise, and Exercise alone were used to stimulate LNCaP cells in culture. Growth and apoptosis of tumor cells were measured. Serum samples were also used to measure insulin, IGF-1, IGFBP-1.

RESULTS

The Diet and Exercise and the Exercise alone groups had lower serum insulin and IGF-1 but higher IGFBP-1 compared to Controls. LNCaP cell growth was reduced in both groups compared to Control and there was a major increase in apoptosis of tumor cells.

CONCLUSIONS

A low-fat diet and/or intensive exercise results in change in serum hormones and growth factors in vivo that can reduce growth and induce apoptosis of LNCaP prostate tumor cells in vitro.

Vaccenic acid (t11-18:1) is converted to c9,t11-CLA in MCF-7 and SW480 cancer cells

The aims of this study were to determine whether vaccenic acid (VA; t11-18:1) is converted to c9,t11-CLA in human mammary (MCF-7) and colon (SW480) cancer cell lines and whether VA influences cell viability and other CLA-bioresponsive markers. When cells were incubated in the presence of VA at concentrations of 5 to 20 microg/mL, both VA and c9,t11-CLA increased in cellular lipids in a dose-dependent manner. After 4 d of incubation of SW480 and MCF-7 cells with VA (20 microg/mL), c9,t11-CLA increased from undetectable levels to 8.57 and 12.14 g/100 g FAME in cellular lipids, respectively. VA supplementation for 4 d at 5, 10, and 15 microg/mL had no effect on cell growth, whereas 20 microg/mL significantly (P < 0.05) reduced cell growth in both cell lines. VA (20 microg/mL) treatment induced DNA fragmentation and significantly (P < 0.05) depleted cytosolic GSH levels in the SW480 cell line after 4 d of incubation, suggesting that apoptosis was the mode of cell death induced by VA. Both VA and c9,t11-CLA reduced (P < 0.05) total ras expression in SW480 cells. 14C-Arachidonic acid uptake into the MG fraction was significantly increased (P < 0.05) in both cell lines while uptake into the phospholipid fraction decreased in response to VA. VA treatment significantly (P < 0.05) increased 8-epi-prostaglandin F2alpha in both cell lines. The data indicate that growth suppression and cellular responses of both cells lines are likely mediated by VA desaturation to c9,t11-CLA via delta9-desaturase.

Lipoxygenase and cyclooxygenase metabolism: new insights in treatment and chemoprevention of pancreatic cancer

The essential fatty acids, linoleic acid and arachidonic acid play an important role in pancreatic cancer development and progression. These fatty acids are metabolized to eicosanoids by cyclooxygenases and lipoxygenases. Abnormal expression and activities of both cyclooxygenases and lipoxygenases have been reported in pancreatic cancer. In this article, we aim to provide a brief summary of (1) our understanding of the roles of these enzymes in pancreatic cancer tumorigenesis and progression; and (2) the potential of using cyclooxygenase and lipoxygenase inhibitors for pancreatic cancer treatment and prevention.

Prostate cancer: another aspect of the insulin-resistance syndrome?

Insulin resistance and compensatory hyperinsulinaemia are thought to be the underlying factors in the metabolic or insulin-resistance syndrome and can be controlled by diet and exercise. Hyperinsulinaemia has been shown to have a direct effect on the live, suppressing the production of sex hormone-binding globulin (SHBG) and insulin-like growth factor-binding proteins 1 and 2 (IGFBP-1, -2) while stimulating the production of insulin-like growth factor 1 (IGF-1). These factors have been proposed to be important modulators of hormone-related cancers, such as prostate cancer. Men adopting a low-fat diet and daily exercise reduced their levels of serum insulin and IGF-1, while increasing their levels of IGFBP-1 and sex hormone-binding globulin (SHBG). Cell-culture studies with LNCaP prostate cancer cells showed apoptosis of tumour cells and a reduction in serum-stimulated cell growth in the post diet and exercise serum. These results suggest that prostate cancer may be another aspect of the insulin-resistance syndrome and that adopting a low-fat diet combined with regular exercise may reduce the risk for prostate and other hormone-related cancers. This needs to be tested with prospective studies.

Dietary polyunsaturated fatty acids and colorectal neoplasia

Epidemiology has implicated dietary fat in mortality associated with some of the most common forms of cancer, including those affecting the intestinal tract, breast and prostate. Polyunsaturated fatty acids, and arachidonate in particular, have been unequivocally linked to experimental colorectal carcinogenesis. Dietary, pharmacologic and genetic manipulation of tissue arachidonic acid and its conversion to bioactive lipids has provided insights into pathogenic mechanisms as well as compelling evidence to support rational preventative and therapeutic methods of disease intervention. While it is clear that conversion of arachidonate to prostaglandins and other bioactive lipids contributes significantly to tumorigenesis in the intestinal tract and other organs, it is also clear that no single metabolic pathway or lipid in this complex biochemical network is solely responsible for dietary or pharmacologic benefits evident in epidemiologic studies. We will review some of these data and provide a summary of our own work showing that conversion of arachidonate to prostaglandin E2 contributes significantly to tumor growth through the modulation of apoptosis and cellular proliferation.

In vitro studies on the relationship between polyunsaturated fatty acids and cancer: tumour or tissue specific effects?

In vitro cell culture experiments have lead to the consensus in the literature that certain PUFAs have a selective cytotoxic or anti-proliferative effect on tumour cells and a minimal, or no effect on normal cells. Re-examination of key publications showed that when normal cells were used for comparison, they were generally not from the same cell, tissue, or species type as the tumour cells. Recently, investigations have included more appropriate normal control cells, and though tumour specific cytotoxic/anti-proliferative PUFA effects are found in some cell types, in others the normal cells are more sensitive. Cell type differences were found in the relative ability of individual PUFAs to act. However, within a cell type differences in susceptibility were influenced by grade and stage of tumour, immortalisation and tumourigenic status, cell culture media and cell plating density. Together these results suggest that the consensus is not valid, and that susceptibility to PUFA is cell type specific, and alters during neoplastic progression. Furthermore, the cytotoxic/anti-proliferative effect induced by both n-3 and n-6 PUFAs on a wide variety of cell types, associated with an increase in lipid peroxidation in vitro, cannot account for the in vivo data on the relationship between dietary fat and certain cancers. However, the effects of PUFAs and their metabolites on cell signalling pathways may explain the in vivo data.

Promoting effect of a high-fat/high-protein diet in DMBA-induced ductal pancreatic cancer in rats

OBJECTIVE

To investigate whether a high-fat/high-protein diet (HFPD) acts as a promoter of the natural course of cancer growth in the 7,12-dimethylbenzanthracene (DMBA)-induced ductal pancreatic cancer model in rats.

SUMMARY BACKGROUND DATA

DMBA implantation to the rat pancreas induces ductal adenocarcinoma. Information regarding the effects of diet and the presence of K-ras mutation in this model is not available.

METHODS

Rats were randomly assigned to regular rat chow or a diet with a 30% content in fat and protein (HFPD). The presentation of cancer, the histologic spectrum of neoplasia at 1 and 9 months, and the prevalence of cancer in relation to diet were assessed. Histologic specimens comprising normal ducts, hyperplasia, dysplasia/carcinoma in situ, or carcinoma were designated by a pathologist and microdissected. Genomic DNA was extracted, and K-ras and H-ras gene mutations were determined by a mutant-enriched polymerase chain reaction assay and direct sequencing.

RESULTS

Rats fed HFPD increased their weight significantly compared with controls. DMBA induced characteristic stages of neoplasia at the implant site but not elsewhere. Macroscopic cancers of the pancreatic head presented regularly with common bile duct and gastric outlet obstruction. The prevalence of K-ras mutations was proportional to the degree of epithelial abnormality. K-ras mutations were significantly more frequent in cancer than in normal and hyperplastic ducts. H-ras mutations were not found. At 1 month in the HFPD-fed rats, the prevalence of cancer (16%) and dysplasia (16%) was not significantly different from the prevalence of cancer (29%) and dysplasia (8%) in the chow-fed rats. At 9 months the prevalence of cancer in the HFPD-fed rats increased to 29%, whereas that in the chow-fed rats decreased to 17%. The combined prevalence of cancer and dysplasia at 9 months in the HFPD-fed rats (34%) significantly exceeded that in the chow-fed rats.

CONCLUSIONS

DMBA induces characteristic stages of neoplasia in the evolution of ductal pancreatic cancer in rats. K-ras mutations occur progressively in the ladder of oncogenesis, as in human pancreatic neoplasms. The addition of a diet with a high fat and protein content acts as a promoter of carcinogenesis, possibly by interfering with repair mechanisms and natural regression of early lesions.