The microtubule end-binding protein EB2 is a central regulator of microtubule reorganisation in apico-basal epithelial differentiation.

Microtubule end-binding (EB) proteins influence microtubule dynamic instability, a process that is essential for microtubule reorganisation during apico-basal epithelial differentiation. Here, we establish for the first time that expression of EB2, but not that of EB1, is crucial for initial microtubule reorganisation during apico-basal epithelial differentiation, and that EB2 downregulation promotes bundle formation. EB2 siRNA knockdown during early stages of apico-basal differentiation prevented microtubule reorganisation, whereas its downregulation at later stages promoted microtubule stability and bundle formation. Interestingly, although EB1 is not essential for microtubule reorganisation, its knockdown prevented apico-basal bundle formation and epithelial elongation. siRNA depletion of EB2 in undifferentiated epithelial cells induced the formation of straight, less dynamic microtubules with EB1 and ACF7 lattice association and co-alignment with actin filaments, a phenotype that could be rescued by inhibition with formin. Importantly, in situ inner ear and intestinal crypt epithelial tissue revealed direct correlations between a low level of EB2 expression and the presence of apico-basal microtubule bundles, which were absent where EB2 was elevated. EB2 is evidently important for initial microtubule reorganisation during epithelial polarisation, whereas its downregulation facilitates EB1 and ACF7 microtubule lattice association, microtubule-actin filament co-alignment and bundle formation. The spatiotemporal expression of EB2 thus dramatically influences microtubule organisation, EB1 and ACF7 deployment and epithelial differentiation.

Patterns of DNA methylation in individual colonic crypts reveal aging and cancer-related field defects in the morphologically normal mucosa.

Methylation of CpG islands (CGIs) in the promoter regions of tumour suppressor genes is common in colorectal cancer and occurs also in an age-dependent manner in the morphologically normal colorectal mucosa. In this study, we quantified the level of methylation of six genes associated with the Wnt signalling pathway (adenomatous polyposis coli, DKK1, WIF1, SFRP1, SFRP2 and SFRP5) together with long-interspersed nuclear element-1 as a surrogate for global methylation. DNA methylation was analysed in 260 individual colorectal crypts obtained from eight female patients with no evidence of colorectal disease and five with colorectal cancer. Significant variation in methylation levels for each of the six genes existed between crypts from the same biopsy. The variation in both global and gene-specific CGI methylation between crypts from the same individual was significantly less than that between individuals. Bisulphite sequencing provided insight into the mechanism of aberrant methylation showing that CGI methylation occurs in an 'all-or-none' manner by the directional spreading of methylation from further upstream. Univariate statistical analyses revealed that there were significant differences in crypt-specific methylation associated with both aging and disease status. A multivariate statistical modelling approach was able to distinguish both subject age and health status based on crypt-specific methylation profiles. Our results indicate that the differential methylation of genes associated with the Wnt signalling pathway affecting individual morphologically normal crypts may contribute to the age-dependent generation of the colonic field defect and, in combination with mutations, to the stepwise development of colorectal neoplasia.

Increasing fish consumption does not affect genotoxicity markers in the colon in an intervention study.

Observational studies suggest that fish consumption is associated with a decreased colorectal cancer (CRC) risk. A possible mechanism by which fish could reduce CRC risk is by decreasing colonic genotoxicity. However, concerns have also been raised over the levels of toxic compounds found in mainly oil-rich fish, which could increase genotoxicity. Therefore, the objective was to investigate the effects of fish on genotoxicity markers in the colon in a randomized controlled parallel intervention study. For a period of 6 months, subjects were randomly allocated to receive two extra weekly portions of (i) oil-rich fish (salmon), (ii) lean fish (cod) or (iii) just dietary advice (DA). The Comet Assay was used to measure the DNA damage-inducing potential of fecal water (n = 89) and DNA damage in colonocytes (n = 70) collected pre- and post-intervention as markers of genotoxicity. Genotoxicity of fecal water was not markedly changed after fish consumption: 1.0% increase in tail intensity (TI) [95% confidence interval (CI) -5.1; 7.0] in the salmon group and 0.4% increase in TI (95% CI -5.3; 6.1) in the cod group compared with the DA group. DNA damage in colonocytes was also not significantly changed after fish consumption, in either the salmon group (-0.5% TI, 95% CI -6.9; 6.0) or cod group (-3.3% TI, 95% CI -10.8; 4.3) compared with the DA group. Measurements of genotoxicity of fecal water and DNA damage in colonocytes did not correlate (r = 0.06, n = 34). In conclusion, increasing consumption of either oil-rich or lean fish did not affect genotoxicity markers in the colon.

Fish fatty acids alter markers of apoptosis in colorectal adenoma and adenocarcinoma cell lines but fish consumption has no impact on apoptosis-induction ex vivo.

Previous studies suggest that the n-3 polyunsaturated fatty acids (PUFAs) eicosapenteinoic acid (EPA) and docosahexaenoic acid (DHA), constituents of fish oil, exert chemopreventive activity in colon cancer. One of the mechanisms involved is the facilitation of apoptosis. While a pro-apoptotic potential of n-3 PUFAs has been suggested, it is still unclear whether additional consumption of fish will also lead to comparable results. The aim of this study was to assess EPA- and DHA-mediated effects on endpoints of apoptosis and to use a novel biomarker-approach to measure modulation of apoptosis by consumption of fish. LT97 human colon adenoma and HT29 human colon adenocarcinoma cells were used to investigate modulation of apoptosis by EPA, DHA or linoleic acid (LA) using a set of endpoints, namely phosphatidylserine staining with Annexin-V (flow cytometry), Bcl-2 expression (Real-time RT-PCR), and Bid, caspase 3, 8 and 9 expression as well as PARP cleavage (Western Blot). Furthermore, faecal water (FW) of volunteers (n = 89) from a human trial intervening with fish was used to investigate changes in apoptosis by flow cytometry. DHA was more effective at inducing apoptosis than EPA. LT97 cells were more prone to DHA and EPA induced apoptosis than HT29 cells. Treatment of LT97 cells with FW from volunteers consuming fish did not result in any changes in apoptosis. Taken together, our results show that adenoma cells are highly susceptible to n-3 PUFA-induced apoptosis. By using a biomarker-approach (FW) to measure apoptosis-induction ex vivo no change in apoptosis after additional fish consumption was detectable.

Increased consumption of fatty and lean fish reduces serum C-reactive protein concentrations but not inflammation markers in feces and in colonic biopsies.

Fish consumption is associated with a reduced colorectal cancer risk. A possible mechanism by which fish consumption could decrease colorectal cancer risk is by reducing inflammation. However, thus far, intervention studies investigating both systemic and local gut inflammation markers are lacking. Our objective in this study was to investigate the effects of fatty and lean fish consumption on inflammation markers in serum, feces, and gut. In an intervention study, participants were randomly allocated to receive dietary advice (DA) plus either 300 g of fatty fish (salmon) or 300 g of lean fish (cod) per week for 6 mo, or only DA. Serum C-reactive protein (CRP) concentrations were measured pre- and postintervention (n = 161). In a subgroup (n = 52), we explored the effects of the fish intervention on fecal calprotectin and a wide range of cytokines and chemokines in fecal water and in colonic biopsies. Serum CRP concentrations were lower in the salmon (-0.5 mg/L; 95% CI -0.9, -0.2) and cod (-0.4 mg/L; 95% CI -0.7, 0.0) groups compared with the DA group. None of the inflammation markers in fecal water and colonic biopsies differed between the DA group and the groups that consumed extra fish. In conclusion, increasing salmon or cod consumption for 6 mo resulted in lower concentrations of the systemic inflammation marker CRP. However, exploratory analysis of local markers of inflammation in the colon or feces did not reveal an effect of fish consumption.

Ulcerative colitis and irritable bowel patients exhibit distinct abnormalities of the gut microbiota.

BACKGROUND: Previous studies suggest a link between gut microbiota and the development of ulcerative colitis (UC) and irritable bowel syndrome (IBS). Our aim was to investigate any quantitative differences in faecal bacterial compositions in UC and IBS patients compared to healthy controls, and to identify individual bacterial species that contribute to these differences. METHODS: Faecal microbiota of 13 UC patients, 11 IBS patients and 22 healthy volunteers were analysed by PCR-Denaturing Gradient Gel Electrophoresis (DGGE) using universal and Bacteroides specific primers. The data obtained were normalized using in-house developed statistical method and interrogated by multivariate approaches. The differentiated bands were excised and identified by sequencing the V3 region of the 16S rRNA genes. RESULTS: Band profiles revealed that number of predominant faecal bacteria were significantly different between UC, IBS and control group (p < 10-4). By assessing the mean band numbers in UC (37 ± 5) and IBS (39 ± 6), compared to the controls (45 ± 3), a significant decrease in bacterial species is suggested (p = 0.01). There were no significant differences between IBS and UC. Biodiversity of the bacterial species was significantly lower in UC (µ = 2.94, σ = 0.29) and IBS patients (µ = 2.90, σ = 0.38) than controls (µ = 3.25, σ = 0.16; p = 0.01). Moreover, similarity indices revealed greater biological variability of predominant bacteria in UC and IBS compared to the controls (median Dice coefficients 76.1% (IQR 70.9 - 83.1), 73.8% (IQR 67.0 - 77.5) and 82.9% (IQR 79.1 - 86.7) respectively). DNA sequencing of discriminating bands suggest that the presence of Bacteroides vulgatus, B. ovatus, B. uniformis, and Parabacteroides sp. in healthy volunteers distinguishes them from IBS and UC patients. DGGE profiles of Bacteroides species revealed a decrease of Bacteroides community in UC relative to IBS and controls. CONCLUSION: Molecular profiling of faecal bacteria revealed abnormalities of intestinal microbiota in UC and IBS patients, while different patterns of Bacteroides species loss in particular, were associated with UC and IBS.

Systemic iron reduction by venesection alters the gut microbiome in patients with haemochromatosis.

BACKGROUND & AIMS: Iron reduction by venesection has been the cornerstone of treatment for haemochromatosis for decades, and its reported health benefits are many. Repeated phlebotomy can lead to a compensatory increase in intestinal iron absorption, reducing intestinal iron availability. Given that most gut bacteria are highly dependent on iron for survival, we postulated that, by reducing gut iron levels, venesection could alter the gut microbiota. METHODS: Clinical parameters, faecal bacterial composition and metabolomes were assessed before and during treatment in a group of patients with haemochromatosis undergoing iron reduction therapy. RESULTS: Systemic iron reduction was associated with an alteration of the gut microbiome, with changes evident in those who experienced reduced faecal iron availability with venesection. For example, levels of Faecalibacterium prausnitzii, a bacterium associated with improved colonic health, were increased in response to faecal iron reduction. Similarly, metabolomic changes were seen in association with reduced faecal iron levels. CONCLUSION: These findings highlight a significant shift in the gut microbiome of patients who experience reduced colonic iron during venesection. Targeted depletion of faecal iron could represent a novel therapy for metabolic and inflammatory diseases, meriting further investigation. LAY SUMMARY: Iron depletion by repeated venesection is the mainstay of treatment for haemochromatosis, an iron-overload disorder. Venesection has been associated with several health benefits, including improvements in liver function tests, reversal of liver scarring, and reduced risk of liver cancer. During iron depletion, iron absorption from the gastrointestinal (GI) tract increases to compensate for iron lost with treatment. Iron availability is limited in the GI tract and is crucial to the growth and function of many gut bacteria. In this study we show that reduced iron availability in the colon following venesection treatment leads to a change in the composition of the gut bacteria, a finding that, to date, has not been studied in patients with haemochromatosis.

Involvement of KLF4 in sulforaphane- and iberin-mediated induction of p21(waf1/cip1).

Sulforaphane (SF; 4-methylsulfinylbutyl isothiocyanate), a dietary compound derived from broccoli, may exhibit chemopreventive properties by inducing cell cycle arrest via induction of cyclin-dependent kinase inhibitor 1A (p21(waf1/cip1)), but the exact molecular mechanism has not been determined. Here we evaluate the role of the transcription factor Kruppel-like factor 4 (KLF4) in mediating the induction of p21(waf1/cip1) and cellular differentiation by SF and iberin (IB; 3-methylsulphinyl propyl isothiocyanate), also derived from broccoli. Exposure of Caco-2 and Caco-2/TC7 cells to SF and IB increased expression of both KLF4 and p21(waf1/cip1), whereas exposure of HT29 cells resulted only in induction of p21(waf1/cip1). In Caco-2 cells, small interfering RNA knock down of KLF4 expression attenuated induction of p21(waf1/cip1) in response to either SF or IB treatment. Contrary to expectation, prolonged exposure to SF reduced sucrase isomaltase activity, a marker of small intestinal differentiation in Caco-2 cells. Additional support for the SF-mediated induction of p21(waf1/cip1) by KLF4 was obtained from analyses of gastric tissue of Apc(Min/+) mice following acute intervention with SF but not from the analyses of other tissue of the intestinal tract. These results suggest that induction of p21(waf1/cip1) by SF or IB may be partly mediated by KLF4 in some colon cancer cells and tissues.

A comparison of the effects of soya isoflavonoids and fish oil on cell proliferation, apoptosis and the expression of oestrogen receptors alpha and beta in the mammary gland and colon of the rat.

Isoflavonoids and fish oil may be protective against colorectal cancer, but the evidence in relation to breast cancer risk is ambiguous. In the present study, we have investigated the impact of soya-derived isoflavonoids and n-3 fatty acids from fish oil, both individually and in combination, on apoptosis, cell proliferation and oestrogen receptor (ER) expression in the colon and mammary gland of the rat. Female rats were fed diets high in n-3 fatty acids (80 g/kg diet) or soya protein (765 mg/kg diet isoflavones) for 2 weeks, and then killed before the removal of the colon and mammary glands. Cell proliferation and apoptosis were quantified morphologically in whole crypts and terminal end buds. The expressions of ERalpha and ERbeta were measured in colon tissue scrapes and the mammary gland. Fish oil significantly increased apoptosis and decreased mitosis in both tissues, an effect associated with a decrease in the expressions of ERalpha and ERbeta. Soya had no effect on apoptosis in either tissue, but reduced mitosis in the colon (P < 0.001) while increasing it in the mammary gland (P = 0.001). The changes in proliferation were associated with contrasting changes in the ER expression such that fish oil significantly decreased both ERbeta and ERalpha, while soya increased ERalpha and decreased ERbeta. The results may provide a novel mechanism by which n-3 fatty acids could reduce cancer risk, but the interpretation of the results in relation to soya consumption and breast cancer risk requires further investigation.

L-alpha-glycerophosphocholine contributes to meat's enhancement of nonheme iron absorption.

In this research, our aim was to isolate and characterize the substance known as "meat factor," which is reported to enhance nonheme iron absorption. We used various analytical techniques, and the final step was a human study to measure the effect of a candidate compound on iron absorption. Lean beef was selected for study, as it is known to increase nonheme iron absorption. Cooked ground beef was homogenized and aliquots were taken through a simulated gastric and intestinal digestion. This was followed by purification using fast protein liquid chromatography. The fractions were collected and applied to a Caco-2 cell system designed to measure iron absorption using radioiron. Fractions with an enhancing effect were analyzed by mass spectrometry, nuclear magnetic resonance, and HPLC, and a proposed empirical formula was obtained for the substance in the most active fraction (C(8)H(20) NO(6)P). Tandem mass spectrometry was used to identify the compound as L-alpha-glycerophosphocholine (L-alpha) by comparing the spectra against authentic material. We added a commercially available food grade source of L-alpha to vegetarian lasagna, with and without 100 mg ascorbic acid (a known enhancer of nonheme iron absorption), at the same enhancer:iron molar ratio (2:1), and fed meals to 13 women of child-bearing age with low iron stores. The nonheme iron was labeled with stable isotopes of iron to provide a total dose per meal of 10 mg iron, and absorption was measured from erythrocyte incorporation. Nonheme iron absorption from lasagna was increased by the addition of either ascorbic acid (P = 0.010) or L-alpha (P = 0.023). We have identified L-alpha as a component of muscle tissue that enhances nonheme iron absorption, and this finding provides new opportunities for iron fortification of foods.

Comparing Diet and Exercise Monitoring Using Smartphone App and Paper Diary: A Two-Phase Intervention Study.

BACKGROUND: There is increasing recognition that personalized approaches may be more effective in helping people establish healthier eating patterns and exercise more, and that this approach may be particularly effective in adolescents. OBJECTIVE: The objective of this study was to investigate the use of a smartphone app (FoodWiz2) in supporting healthy lifestyle choices in adolescence. METHODS: Participants (N=34: 11 male, 23 female) aged 16-19 years in full- or part-time education were recruited from sixth form colleges, schools, and other further education establishments in Norfolk and Suffolk, United Kingdom, between February and May 2015. Participants recorded food intake and exercise using a paper diary for 4-5 weeks and then used the app for the same duration. Initial nutrition education and general support were provided during the paper diary use, but the app included personalized messages sent in response to app activity. At the end of each study phase, participants completed an online questionnaire to describe their experience of using the paper diary and app. RESULTS: Record completion declined throughout the study, possibly affected by examination pressure. Food intake data showed increased fruit consumption and significantly reduced consumption of chocolate snacks (P=.01) and fizzy drinks (P=.002) among participants using the app. Questionnaire responses indicated that the app was generally preferred to the paper diary, in particular, the app was seen as less boring to use (P=.03) and more acceptable in social settings (P<.001). CONCLUSIONS: This app-based approach has shown the potential for a more effective approach to improving adolescent diet and exercise levels.

Immuno-fluorescent Labeling of Microtubules and Centrosomal Proteins in Ex Vivo Intestinal Tissue and 3D In Vitro Intestinal Organoids.

The advent of 3D in vitro organoids that mimic the in vivo tissue architecture and morphogenesis has greatly advanced the ability to study key biological questions in cell and developmental biology. In addition, organoids together with recent technical advances in gene editing and viral gene delivery promises to advance medical research and development of new drugs for treatment of diseases. Organoids grown in vitro in basement matrix provide powerful model systems for studying the behavior and function of various proteins and are well suited for live-imaging of fluorescent-tagged proteins. However, establishing the expression and localization of the endogenous proteins in ex vivo tissue and in in vitro organoids is important to verify the behavior of the tagged proteins. To this end we have developed and modified tissue isolation, fixation, and immuno-labeling protocols for localization of microtubules, centrosomal, and associated proteins in ex vivo intestinal tissue and in in vitro intestinal organoids. The aim was for the fixative to preserve the 3D architecture of the organoids/tissue while also preserving antibody antigenicity and enabling good penetration and clearance of fixative and antibodies. Exposure to cold depolymerizes all but stable microtubules and this was a key factor when modifying the various protocols. We found that increasing the ethylenediaminetetraacetic acid (EDTA) concentration from 3 mM to 30 mM gave efficient detachment of villi and crypts in the small intestine while 3 mM EDTA was sufficient for colonic crypts. The developed formaldehyde/methanol fixation protocol gave very good structural preservation while also preserving antigenicity for effective labeling of microtubules, actin, and the end-binding (EB) proteins. It also worked for the centrosomal protein ninein although the methanol protocol worked more consistently. We further established that fixation and immuno-labeling of microtubules and associated proteins could be achieved with organoids isolated from or remaining within the basement matrix.

Ninein is essential for apico-basal microtubule formation and CLIP-170 facilitates its redeployment to non-centrosomal microtubule organizing centres.

Differentiation of columnar epithelial cells involves a dramatic reorganization of the microtubules (MTs) and centrosomal components into an apico-basal array no longer anchored at the centrosome. Instead, the minus-ends of the MTs become anchored at apical non-centrosomal microtubule organizing centres (n-MTOCs). Formation of n-MTOCs is critical as they determine the spatial organization of MTs, which in turn influences cell shape and function. However, how they are formed is poorly understood. We have previously shown that the centrosomal anchoring protein ninein is released from the centrosome, moves in a microtubule-dependent manner and accumulates at n-MTOCs during epithelial differentiation. Here, we report using depletion and knockout (KO) approaches that ninein expression is essential for apico-basal array formation and epithelial elongation and that CLIP-170 is required for its redeployment to n-MTOCs. Functional inhibition also revealed that IQGAP1 and active Rac1 coordinate with CLIP-170 to facilitate microtubule plus-end cortical targeting and ninein redeployment. Intestinal tissue and in vitro organoids from the Clip1/Clip2 double KO mouse with deletions in the genes encoding CLIP-170 and CLIP-115, respectively, confirmed requirement of CLIP-170 for ninein recruitment to n-MTOCs, with possible compensation by other anchoring factors such as p150Glued and CAMSAP2 ensuring apico-basal microtubule formation despite loss of ninein at n-MTOCs.

Effects of Brussels sprout juice on the cell cycle and adhesion of human colorectal carcinoma cells (HT29) in vitro.

Consumption of Brassica vegetables is associated with a reduced risk of cancer of the alimentary tract in animal models and human populations. We used raw juice extracted from Brussels sprouts rich in the glucosinolate sinigrin to explore the effect of naturally occurring glucosinolate breakdown products on cell cycle progression and apoptosis in human colorectal carcinoma cells (HT29). Juice was prepared from sprout tissue immediately before use, and the glucosinolate breakdown products were determined by gas chromatography mass spectrometry and liquid chromatography mass spectrometry. The cell cycle was analyzed by flow cytometry on detached and adherent cells, and apoptosis was measured in the detached population by annexin V staining. Twenty-four hours after challenge with juice (10 microL/mL), 7-13% of adherent cells had detached from the substratum but the majority (82%) of these cells had not entered apoptosis, whereas only 33% of detached control cells were not apoptotic (p < 0.05). The main glucosinolate breakdown products were as follows: the sinigrin breakdown product, 1-cyano-2,3-epithiopropane (ca. 38 mM); the gluconapin hydrolysis product, 3-butenyl isothiocyanate (ca. 2.2.mM); the glucobrassicin metabolite, ascorbigen (ca. 8 mM); and low concentrations of other indole glucosinolate-derived hydrolysis products such as neoascorbigen and 3,3'-diindolylmethane. A variety of biologically active glucosinolate breakdown products are released by mechanical disruption of raw Brussels sprout tissue, but contrary to previous assumptions, allyl isothiocyanate is not the main compound responsible for the inhibition of cell proliferation.

Polyunsaturated fatty acids modify expression of TGF-ß in a co-culture model ultilising human colorectal cells and human peripheral blood mononuclear cells exposed to Lactobacillus gasseri, Escherichia coli and Staphylococcus aureus.

Commensal bacteria and polyunsaturated fatty acids (PUFAs) have both been shown independently to modulate immune responses. This study tested the hypothesis that the different colonic immunomodulatory responses to commensal (Lactobacillus gasseri) and pathogenic bacteria (Escherichia coli and Staphylococcus aureus) may be modified by PUFAs. Experiments used a Transwell system combining the colorectal cell line HT29, or its mucous secreting sub-clone HT29-MTX, with peripheral blood mononuclear cells to analyse immunomodulatory signalling in response to bacteria, with and without prior treatment with arachidonic acid, eicosapentaenoic acid or docosahexaenoic acid. L. gasseri increased transforming growth factor ß1 (TGF-ß1) mRNA and protein secretion in colonic cell lines when compared with controls, an effect that was enhanced by pre-treatment with eicosapentaenoic acid. In contrast, the Gram-negative pathogen E. coli LF82 had no significant effect on TGF-ß1 protein. L. gasseri also increased IL-8 mRNA but not protein while E. coli increased both; although differences between PUFA treatments were detected, none were significantly different to controls. Colonic epithelial cells show different immunomodulatory signalling patterns in response to the commensal L. gasseri compared to E. coli and S. aureus and pre-treatment of these cells with PUFAs can modify responses. Practical applications: We have demonstrated an interaction between dietary PUFAs and epithelial cell response to both commensal and pathogenic bacteria found in the gastrointestinal tract by utilising in vitro co-culture models. The data suggest that n-3 PUFAs may provide some protection against the potentially damaging effects of pathogens. Furthermore, the beneficial effects of combining n-3 PUFAs and the commensal bacteria, and potential probiotic, L. gasseri are illustrated by the increased expression of immunoregulatory TGF-ß1.

Health benefits of seafood; is it just the fatty acids?

There is a considerable body of literature suggesting a wide range of health benefits associated with diets high in seafood. However, the demand for seafood across the world now exceeds that available from capture fisheries. This has created a rapidly increasing market for aquaculture products, the nutrient composition of which is dependent on feed composition. The use of fishmeal in this food chain does little to counteract the environmental impact of fisheries and so the on-going development of alternative sources is to be welcomed. Nevertheless, an in-depth understanding as to which nutrients in seafood provide benefit is required to permit the production of foods of maximal health benefit to humans. This paper reviews our current knowledge of the beneficial nutrient composition of seafood, in particular omega-3 fatty acids, selenium, taurine, vitamins D and B12, in the context of the development of environmentally sustainable aquaculture.

Recent advances in understanding the role of diet and obesity in the development of colorectal cancer.

Colorectal cancer (CRC) is a major cause of premature death in the UK and many developed countries. However, the risk of developing CRC is well recognised to be associated not only with diet but also with obesity and lack of exercise. While epidemiological evidence shows an association with factors such as high red meat intake and low intake of vegetables, fibre and fish, the mechanisms underlying these effects are only now being elucidated. CRC develops over many years and is typically characterised by an accumulation of mutations, which may arise as a consequence of inherited polymorphisms in key genes, but more commonly as a result of spontaneously arising mutations affecting genes controlling cell proliferation, differentiation, apoptosis and DNA repair. Epigenetic changes are observed throughout the progress from normal morphology through formation of adenoma, and the subsequent development of carcinoma. The reasons why this accumulation of loss of homoeostatic controls arises are unclear but chronic inflammation has been proposed to play a central role. Obesity is associated with increased plasma levels of chemokines and adipokines characteristic of chronic systemic inflammation, and dietary factors such as fish oils and phytochemicals have been shown to have anti-inflammatory properties as well as modulating established risk factors such as apoptosis and cell proliferation. There is also some evidence that diet can modify epigenetic changes. This paper briefly reviews the current state of knowledge in relation to CRC development and considers evidence for potential mechanisms by which diet may modify risk.

Identification of the Eph receptor pathway as a novel target for eicosapentaenoic acid (EPA) modification of gene expression in human colon adenocarcinoma cells (HT-29).

BACKGROUND: The health benefits of polyunsaturated fatty acids (PUFAs), particularly those of the n-3 series are well documented. The mechanisms by which these effects are mediated are not fully clarified. METHODS: We used microarrays to assess the effects on gene expression in HT29 colon adenocarcinoma cells of exposure to the n-3 fatty acid eicosapentaenoic acid (EPA). HT29 cells were cultured with EPA (150 muM) for up to 24 hr prior to harvesting and isolation of RNA. Microarray results were analyzed within the statistical package 'R', and GeneGo MetaCore was used to identify key pathways of altered gene expression. RESULTS: EphB4, Vav2 and EphA1 gene expression were identified as significantly altered by EPA treatment. Statistically significant changes in gene expression after HT29 exposure to EPA were confirmed in a second experiment by real-time RT-PCR (TaqMan), This experiment also compared the effects of exposure to EPA to arachadonic acid (AA, n-6). Corresponding changes in protein expression were also assessed by Western blotting. CONCLUSIONS: Eph receptor mediated signaling is an entirely novel signaling pathway through which EPA may promote a wide range of health benefits, in particular in relation to reduction of colorectal cancer progression.

Modulation of gene expression in eicosapentaenoic acid and docosahexaenoic acid treated human colon adenoma cells.

Epidemiological studies suggest that high fish intake is associated with a decreased risk of colorectal cancer which has been linked to the high content of the n-3 polyunsaturated fatty acids (PUFAs) eicosapentaenoic acids (EPA) and docosahexaenoic acid (DHA) in some fish. The aim of the study was to compare the modulation of gene expression in LT97 colon adenoma cells in response to EPA and DHA treatment. Therefore, we used custom-designed cDNA arrays containing probes for 306 genes related to stress response, apoptosis and carcinogenesis and hybridised them with cDNA from LT97 cells which were treated for 10 or 24 h with 50 muM EPA or DHA. There was a marked influence of n-3 PUFA on the expression of several gene types, such as detoxification, cell cycle control, signaling pathways, apoptosis and inflammation. DHA and EPA generally modulated different sets of genes, although a few common effects were noted. In our approach, we used preneoplastic adenoma cells which are a relevant model for target cells of chemoprevention. If verified with real time PCR, these results identify genes and targets for chemoprevention of colon cancer.

Effects of fatty acids on metabolism and cell growth of human colon cell lines of different transformation state.

Epidemiological studies suggest that high fish intake is associated with a decreased risk of colorectal cancer which has been linked to the high content of the n - 3 polyunsaturated fatty acids (PUFAs) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in some fish. In this study, two different cell lines are compared in relation to their response to EPA and DHA versus the plant derived PUFAs, linoleic acid (LA), gamma-linolenic acid (GLA), and alpha-linolenic acid (ALA) and to the ubiquitous arachidonic acid (ARA). The uptake of 100 microM of each fatty acid (FA) was determined using GC. The 4',6-diamidino-2-phenylindole assay for DNA quantification and the Cell-Titer-Blue assay were used to determine cell survival and metabolic activity at 2-72 h after treatment. All FAs were utilized more efficiently by the human colon adenoma cell line LT97 than by the adenocarcinoma cell line HT29. LT97 were more susceptible than HT29 cells to the growth inhibitory activities of all FAs except for DHA where both were equally sensitive. Inhibition of survival and metabolic activity by EPA and DHA increased with treatment time in both cell lines. ALA or GLA were less growth inhibitory than EPA or DHA and ARA had intermediary activity. The data show that the tested FAs are incorporated into colon cells. Furthermore, adenoma cells are more susceptible than the adenocarcinoma cells.