Effects of omega-3 and omega-6 fatty acids on IGF-I receptor signalling in colorectal cancer cells

Dietary α-Linolenic Acid Counters Cardioprotective Dysfunction in Diabetic Mice: Unconventional PUFA Protection

Whether dietary omega-3 (n-3) polyunsaturated fatty acid (PUFA) confers cardiac benefit in cardiometabolic disorders is unclear. We test whether dietary -linolenic acid (ALA) enhances myocardial resistance to ischemia-reperfusion (I-R) and responses to ischemic preconditioning (IPC) in type 2 diabetes (T2D); and involvement of conventional PUFA-dependent mechanisms (caveolins/cavins, kinase signaling, mitochondrial function, and inflammation). Eight-week male C57Bl/6 mice received streptozotocin (75 mg/kg) and 21 weeks high-fat/high-carbohydrate feeding. Half received ALA over six weeks. Responses to I-R/IPC were assessed in perfused hearts. Localization and expression of caveolins/cavins, protein kinase B (AKT), and glycogen synthase kinase-3 β (GSK3β); mitochondrial function; and inflammatory mediators were assessed. ALA reduced circulating leptin, without affecting body weight, glycemic dysfunction, or cholesterol. While I-R tolerance was unaltered, paradoxical injury with IPC was reversed to cardioprotection with ALA. However, post-ischemic apoptosis (nucleosome content) appeared unchanged. Benefit was not associated with shifts in localization or expression of caveolins/cavins, p-AKT, p-GSK3β, or mitochondrial function. Despite mixed inflammatory mediator changes, tumor necrosis factor-a (TNF-a) was markedly reduced. Data collectively reveal a novel impact of ALA on cardioprotective dysfunction in T2D mice, unrelated to caveolins/cavins, mitochondrial, or stress kinase modulation. Although evidence suggests inflammatory involvement, the basis of this "un-conventional" protection remains to be identified.

Omega-3 Fatty Acids Prevent Early Pancreatic Carcinogenesis via Repression of the AKT Pathway

Pancreatic cancer remains a daunting foe despite a vast number of accumulating molecular analyses regarding the mutation and expression status of a variety of genes. Indeed, most pancreatic cancer cases uniformly present with a mutation in the KRAS allele leading to enhanced RAS activation. Yet our understanding of the many epigenetic/environmental factors contributing to disease incidence and progression is waning. Epidemiologic data suggest that diet may be a key factor in pancreatic cancer development and potentially a means of chemoprevention at earlier stages. While diets high in ω3 fatty acids are typically associated with tumor suppression, diets high in ω6 fatty acids have been linked to increased tumor development. Thus, to better understand the contribution of these polyunsaturated fatty acids to pancreatic carcinogenesis, we modeled early stage disease by targeting mutant KRAS to the exocrine pancreas and administered diets rich in these fatty acids to assess tumor formation and altered cell-signaling pathways. We discovered that, consistent with previous reports, the ω3-enriched diet led to reduced lesion penetrance via repression of proliferation associated with reduced phosphorylated AKT (pAKT), whereas the ω6-enriched diet accelerated tumor formation. These data provide a plausible mechanism underlying previously observed effects of fatty acids and suggest that administration of ω3 fatty acids can reduce the pro-survival, pro-growth functions of pAKT. Indeed, counseling subjects at risk to increase their intake of foods containing higher amounts of ω3 fatty acids could aid in the prevention of pancreatic cancer.

Effect of genetic variants and traits related to glucose metabolism and their interaction with obesity on breast and colorectal cancer risk among postmenopausal women

BACKGROUND

Impaired glucose metabolism-related genetic variants and traits likely interact with obesity and related lifestyle factors, influencing postmenopausal breast and colorectal cancer (CRC), but their interconnected pathways are not fully understood. By stratifying via obesity and lifestyles, we partitioned the total effect of glucose metabolism genetic variants on cancer risk into two putative mechanisms: 1) indirect (risk-associated glucose metabolism genetic variants mediated by glucose metabolism traits) and 2) direct (risk-associated glucose metabolism genetic variants through pathways other than glucose metabolism traits) effects.

METHOD

Using 16 single-nucleotide polymorphisms (SNPs) associated with glucose metabolism and data from 5379 postmenopausal women in the Women's Health Initiative Harmonized and Imputed Genome-Wide Association Studies, we retrospectively assessed the indirect and direct effects of glucose metabolism-traits (fasting glucose, insulin, and homeostatic model assessment-insulin resistance [HOMA-IR]) using two quantitative tests.

RESULTS

Several SNPs were associated with breast cancer and CRC risk, and these SNP-cancer associations differed between non-obese and obese women. In both strata, the direct effect of cancer risk associated with the SNP accounted for the majority of the total effect for most SNPs, with roughly 10% of cancer risk due to the SNP that was from an indirect effect mediated by glucose metabolism traits. No apparent differences in the indirect (glucose metabolism-mediated) effects were seen between non-obese and obese women. It is notable that among obese women, 50% of cancer risk was mediated via glucose metabolism trait, owing to two SNPs: in breast cancer, in relation to GCKR through glucose, and in CRC, in relation to DGKB/TMEM195 through HOMA-IR.

CONCLUSIONS

Our findings suggest that glucose metabolism genetic variants interact with obesity, resulting in altered cancer risk through pathways other than those mediated by glucose metabolism traits.

Linoleic and alpha linolenic acids ameliorate streptozotocin-induced diabetes in mice

Streptozotocin (STZ)-induced diabetes in mice progresses with decreased desaturase activities and alterations in the metabolism of essential fatty acids (EFA).

OBJECTIVES

Based on our previous studies with soybean oil that ameliorated the STZ damage in mice, we tested here the accountability of its main EFA components, i.e. linoleic acid (LA) and alpha linolenic acid (ALA), in the prevention of pancreas damage and Δ6 desaturase decrease.

MATERIALS AND METHODS

Seven days after injection with STZ and EFA gavage, ICR mice were sacrificed. Plasma glucose and insulin levels, pancreas histology and liver fatty acid desaturases were analysed.

RESULTS

EFA reduced pancreas damage, insulin and glucose plasma levels and restored Δ6 desaturase activity and mRNA expression levels.

DISCUSSION

By reducing pancreas damage, EFA ameliorated insulin levels, Δ6 desaturase and fatty acid metabolism. LA further enhanced Fads2 promoter activity.

CONCLUSION

EFA ameliorate STZ induced diabetes in mice.

Prioritizing cancer therapeutic small molecules by integrating multiple OMICS datasets

Drug design is crucial for the effective discovery of anti-cancer drugs. The success or failure of drug design often depends on the leading compounds screened in pre-clinical studies. Many efforts, such as in vivo animal experiments and in vitro drug screening, have improved this process, but these methods are usually expensive and laborious. In the post-genomics era, it is possible to seek leading compounds for large-scale candidate small-molecule screening with multiple OMICS datasets. In the present study, we developed a computational method of prioritizing small molecules as leading compounds by integrating transcriptomics and toxicogenomics data. This method provides priority lists for the selection of leading compounds, thereby reducing the time required for drug design. We found 11 known therapeutic small molecules for breast cancer in the top 100 candidates in our list, 2 of which were in the top 10. Furthermore, another 3 of the top 10 small molecules were recorded as closely related to cancer treatment in the DrugBank database. A comparison of the results of our approach with permutation tests and shared gene methods demonstrated that our OMICS data-based method is quite competitive. In addition, we applied our method to a prostate cancer dataset. The results of this analysis indicated that our method surpasses both the shared gene method and random selection. These analyses suggest that our method may be a valuable tool for directing experimental studies in cancer drug design, and we believe this time- and cost-effective computational strategy will be helpful in future studies in cancer therapy.

Combined supplementation of vanadium and fish oil suppresses tumor growth, cell proliferation and induces apoptosis in DMBA-induced rat mammary carcinogenesis

The anti-cancer activity of vanadium and fish oil has been shown in a large number of studies. This study was undertaken to analyze the combined effect of vanadium and fish oil on 7,12-dimethylbenz(α)anthracene (DMBA)-induced mammary carcinogenesis in female Sprague-Dawley rats. The whole experiment was divided into three parts: (1) DNA strand breaks study, (2) morphological analysis, and (3) histological and immunohistochemical study. Rats were treated with DMBA (0.5 mg/0.2 ml corn oil/100 g body weight) by a tail vein injection. Rats received vanadium (w/v) as ammonium monovanadate at a concentration of 0.5 ppm (4.27 µmol/L) in the drinking water and given ad libitum and/or fish oil (0.5 ml/day/rat) by oral gavage. Histology, morphology, DNA strand breaks, cell proliferation, and apoptosis of the mammary tissue were assessed in this study. Treatment with vanadium or fish oil alone significantly reduced the DNA strand breaks, palpable mammary tumors, tumor multiplicity, and cell proliferation but the maximum protection effect was found in the group that received both vanadium and fish oil and the combination treatment offered an additive effect (P < 0.05). Furthermore, vanadium and fish oil significantly increased the TUNEL-positive apoptotic cells (P < 0.05) but the increase was maximal with combination treatment and had an additive effect. These results affirm the benefits of administration of vanadium and fish oil in the prevention of rat mammary carcinogenesis which was associated with reduced DNA strand breaks, palpable mammary tumors and cell proliferation and increased TUNEL-positive apoptotic cells.

Maternal α-linolenic acid availability during gestation and lactation alters the postnatal hippocampal development in the mouse offspring

The availability of ω-3 polyunsaturated fatty acids is essential for perinatal brain development. While the roles of docosahexaenoic acid (the most abundant ω-3 species) were extensively described, less is known about the role of α-linolenic acid (ALA), which is the initial molecular species undergoing elongation and desaturation within the ω-3 pathways. This study describes the association between maternal ALA availability during gestation and lactation, and alterations in hippocampal development (dentate gyrus) in the mouse male offspring, at the end of lactation (postnatal day 19, P19). Postnatal ALA supplementation increased cell proliferation (36% more proliferating cells compared to a control group) and early neuronal differentiation, while postnatal ALA deficiency increased cellular apoptosis within the dentate gyrus of suckling pups (61% more apoptotic cells compared to a control group). However, maternal ALA deficiency during gestation prevented the increased neurogenesis induced by postnatal supplementation. Fatty acid analysis revealed that ALA supplementation increased the concentration of the ω-3 species in the maternal liver and serum, but not in the brain of the offspring, excepting for ALA itself. Interestingly, ALA supplementation also increased the concentration of dihomo γ-linolenic acid (a ω-6 species) in the P19 brains, but not in maternal livers or serum. In conclusion, postnatal ALA supplementation enhances neurogenesis in the dentate gyrus of the offspring at postnatal day 19, but its beneficial effects are offset by maternal ALA deficiency during gestation. These results suggest that ALA is required in both fetal and postnatal stages of brain development.

Omega-3 fatty acids induce apoptosis in human breast cancer cells and mouse mammary tissue through syndecan-1 inhibition of the MEK-Erk pathway

Human epidemiological studies have shown that diets enriched in n-3 polyunsaturated fatty acids (n-3 PUFA) are associated with a lower incidence of cancers including breast cancer. Our previous studies showed that the n-3 PUFA, docosahexaenoic acid (DHA), upregulated syndecan-1 (SDC-1) expression to induce apoptosis in the human breast cancer cell line MCF-7. We now present evidence of a signaling pathway that is impacted by SDC-1 in these cells and in mouse mammary tissues to result in apoptosis. In MCF-7 cells and SK-BR-3 cells, DHA and a SDC-1 ectodomain impaired signaling of the p44/42 mitogen-activated protein kinase (MAPK) pathway by inhibiting the phosphorylation of MAPK/Erk (MEK)/extracellular signal-regulated kinase (Erk) and Bad to induce apoptosis. SDC-1 siRNA significantly enhanced phosphorylation of these signal molecules and blocked the inhibitory effects of DHA on their phosphorylation. SDC-1 siRNA diminished apoptosis of MCF-7 cells, an effect that was markedly blocked by MEK inhibitor, PD98059. In vivo studies used (i) Fat-1 mice, a genetic model able to convert n-6 to n-3 PUFA to result in higher SDC-1 levels in Fat-1 mammary tissue compared with that of wild-type (wt) mice. Phosphorylation of MEK, Erk and Bad was lower in the Fat-1 versus wt tissue and (ii) SDC-1(-/-) mice that demonstrated markedly higher levels of phosphorylated MEK, Erk and Bad in mammary gland tissue compared with those of SDC(+/+) mice. These data elucidate a pathway whereby SDC-1, upregulated by DHA, induces apoptosis in breast cancer cells through inhibition of MEK/Erk/Bad signaling.

Linoleic acid and butyrate synergize to increase Bcl-2 levels in colonocytes

The biological properties of polyunsaturated fatty acid (PUFA) classes have been the source of much contention. For example, n-3 PUFA are chemoprotective, whereas n-6 PUFA may promote tumor development. Since dietary components can have combinatorial effects, we further examined the apoptotic properties of n-3 or n-6 fatty acids when combined with different fiber sources. Mice were fed diets supplemented with either fish oil (FO; enriched in n-3 PUFA) or corn oil (CO; enriched in n-6 PUFA) and nonfermentable (cellulose) or fermentable (pectin) fiber sources. In complementary experiments, immortalized young adult mouse colonic (YAMC) cells were treated with docosahexaenoic acid (DHA; 22:6n-3) or linoleic acid (LA; 18:2n-6) with or without butyrate. Mice fed a FO and pectin diet had significantly (p < 0.05) increased levels of apoptosis in colonocytes compared to all other diets. Similarly, apoptosis was highly induced in DHA and butyrate cotreated YAMC cells. In contrast, in both YAMC and mouse models, LA/CO with butyrate/pectin treatment reduced apoptosis and enhanced expression of bcl-2. The LA and butyrate induced antiapoptotic phenotype was reversed by knocking down bcl-2 using targeted siRNA. In comparison, overexpression of bcl-2 blocked the proapoptotic effect of DHA and butyrate. These data provide new mechanistic insights into the regulation of apoptosis by dietary PUFA and fiber.

Docosahexaenoic acid suppresses neuroinflammatory responses and induces heme oxygenase-1 expression in BV-2 microglia: implications of antidepressant effects for ω-3 fatty acids

Accumulating evidence suggests that the pathophysiology of depression might be associated with neuroinflammation, which could be attenuated by pharmacological treatment for depression. Omega-3 polyunsaturated fatty acids (PUFAs) are anti-inflammatory and exert antidepressant effects. The aim of this study was to identify the molecular mechanisms through which docosahexaenoic acid (DHA), the main omega-3 PUFA in the brain, modulates oxidative reactions and inflammatory cytokine production in microglial and neuronal cells. The results of this study showed that DHA reduced expressions of tumor necrosis factor-α, interleukin-6, nitric oxide synthase, and cyclo-oxygenase-2, induced by interferon-γ, and induced upregulation of heme oxygenase-1 (HO-1) in BV-2 microglia. The inhibitory effect of DHA on nitric oxide production was abolished by HO-1 inhibitor zinc protoporphyrin IX. In addition, DHA caused AKT and ERK activation in a time-dependent manner, and the DHA-induced HO-1 upregulation could be attenuated by PI-3 kinase/AKT and MEK/ERK inhibitors. DHA also increased IKKα/β phosphorylation, IκBα phosphorylation, and IκBα degradation, whereas both nuclear factor-κB and IκB protease inhibitors could inhibit DHA-induced HO-1 expressions. The other major n-3 PUFA, eicosapentaenoic acid, showed similar effects of DHA on inflammation and HO-1 in repeated key experiments. In connecting with inflammation hypothesis of depression and clinical studies supporting the antidepressant effects of omega-3 PUFAs, this study provides a novel implication of the antidepressant mechanisms of DHA.

[Complementary medicine in oncology]

In cancer therapy vastly different kinds of treatment regimens, but as a rule scientifically validated and reviewed, play a central role dependent on the tumor entity. Besides the options of schoolbook medicine complementary, alternative and supportive treatment options are becoming more frequently used in routine clinical practice. Numerous concepts and agents, partly verified in studies and partly based on empirical experiences are being applied. It is our intention to give a survey of the most common agents and concepts and to point out the risks and capabilities.