Anticarcinogenic effects of diet-related apoptosis in the colorectal mucosa

Overexpression of Soybean-Derived Lunasin in Wheat and Assessment of Its Anti-Proliferative Activity in Colorectal Cancer HT-29 Cells

Lunasin is a soybean-derived peptide that exhibits anticancer bioactivity in different cancer cells and has been identified in different plants. However, recent studies revealed through molecular and chemical analyses that lunasin was absent in wheat and other cereals. In this study, the soybean-derived lunasin was cloned into pCAMBIA3300 and we transferred the expression vector into wheat via an Agrobacterium-mediated transformation. The identification of transgenic wheat was detected by polymerase chain reaction, Western blot analysis, and ultra-performance liquid chromatography with tandem mass spectrometry. An enzyme-linked immunosorbent assay showed that lunasin content in transgenic wheat L32-3, L32-6, and L33-1 was 308.63, 436.78, and 349.07 µg/g, respectively, while lunasin was not detected in wild-type wheat. Lunasin enrichment from transgenic wheat displayed an increased anti-proliferative activity compared with peptide enrichment from wild-type wheat in HT-29 cells. Moreover, the results of a real-time quantitative polymerase chain reaction showed a significant elevation in p21, Bax, and caspase-3 expression, while Bcl-2 was significantly downregulated. In conclusion, soybean-derived lunasin was successfully expressed in wheat via Agrobacterium-mediated transformation and may exert anti-proliferative activity by regulating the apoptosis pathway in HT-29 cells, which provides an effective approach to compensate for the absence of lunasin in wheat.

Anti-Proliferative Activity of A Hydrophilic Extract of Manna from Fraxinus angustifolia Vahl through Mitochondrial Pathway-Mediated Apoptosis and Cell Cycle Arrest in Human Colon Cancer Cells

Manna is produced from the spontaneous solidification of the sap of some Fraxinus species, and, owing its content in mannitol, is used in medicine as a mild laxative. Manna is also a rich source of characteristic bio-phenols with reducing, antioxidant and anti-inflammatory properties. This study assesses the activity of a hydrophilic extract of manna (HME) on cellular and molecular events in human colon-rectal cancer cells. HME showed a time- and concentration-dependent anti-proliferative activity, measured by MTT assay, in all the cell lines examined, namely Caco-2, HCT-116 and HT-29. The amounts of HME that caused 50% of cell death after a 24 h treatment were 8.51 ± 0.77, 10.73 ± 1.22 and 28.92 ± 1.99 mg manna equivalents/mL, respectively; no toxicity was observed in normally differentiated Caco-2 intestinal cells. Hydroxytyrosol, a component of HME known for its cytotoxic effects on colon cancer cells, was ineffective, at least at the concentration occurring in the extract. Through flow-cytometric techniques and Western blot analysis, we show that HME treatment causes apoptosis, assessed by phosphatidylserine exposure, as well as a loss of mitochondrial membrane potential, an intracellular formation of reactive oxygen species (ROS), increases in the levels of cleaved PARP-1, caspase 3 and Bax, and a decrease in Bcl-2 expression. Moreover, HME interferes with cell cycle progression, with a block at the G1/S transition. In conclusion, the phytocomplex extracted from manna exerts an anti-proliferative activity on human colon cancer cells through the activation of mitochondrial pathway-mediated apoptosis and cell cycle arrest. Our data may suggest that manna could have the potential to exert chemo-preventive effects for the intestine.

Supplementation with phytoestrogens and insoluble fibers reduces intestinal carcinogenesis and restores ER-β expression in Apc-driven colorectal carcinogenesis

Supplementation with phytoestrogens and insoluble fibers has been reported to reduce duodenal polyps in colectomized familial adenomatous polyposis patients, with a mechanism involving, at least in part, upregulation of estrogen receptor-β subtype, whose expression is lowered during intestinal tumorigenesis. These data suggest a protective effect also in the colon, the main target organ for tumorigenesis in familial adenomatous polyposis and a major cancer type in non-familial (sporadic) cancers. Therefore, we tested whether a similar preparation might reduce tumorigenesis in the colon of Pirc rats (F344/NTac-Apc) mutated in the Apc gene and thus, like familial adenomatous polyposis patients, spontaneously developing multiple tumors in the colon. We first demonstrate that estrogen receptor-β expression in Pirc rat colon is significantly down-regulated compared to age-matched wt rats. Then, Pirc rats aged 1 month were treated for 3 months with Adipol (Adi), a patented preparation containing phytoestrogens and insoluble fibers. Colon tumorigenesis was significantly reduced by Adi treatment (colon tumors/rat were 5.3 ± 0.8 and 2.9 ± 0.3, Mucin Depleted Foci/rat 127 ± 6.6 and 97.1 ± 8.6 in Controls and Adi-treated rats, respectively, means ± SE, P < 0.01). The treatment also normalized colon proliferation pattern along the crypt and significantly increased apoptosis in colon tumors. Estrogen receptor-β expression was increased by Adi treatment, especially in the tumors. These positive effects suggest that Adipol may be exploited as a chemopreventive agent to reduce cancer risk in familial adenomatous polyposis patients and to postpone prophylactic colectomy. Moreover, given the similarities between familial adenomatous polyposis and sporadic colorectal cancer, it might also be used as chemopreventive agent in colorectal cancer patients at risk.

Fish/shellfish intake and the risk of head and neck cancer

Fish intake and other dietary sources of omega-3 fatty acids have been shown to be associated with a reduced risk for some cancers. Although previous studies of head and neck cancer have reported associations with different dietary factors, including reduced risks for fruits and vegetables and putatively healthy dietary patterns, associations specific to fish intake are unclear. This study investigated the association between fish/shellfish intake and risk of squamous cell carcinoma of the head and neck (SCCHN) using data from the Carolina Head and Neck Cancer Epidemiology Study, a population-based case-control study conducted in 46 North Carolina counties with cases recruited from 2002 through 2006. Controls were frequency matched to the cases on age, sex, and race; the final sample size was 1039 cases and 1375 controls. Demographic, lifestyle, and dietary information were collected using an in-person interviewer-administered structured questionnaire. Multivariable-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were estimated with unconditional logistic regression. Patients whose fish/shellfish intake was among the highest tertile had a 20% lower odds of SCCHN compared with those in the lowest tertile (OR: 0.80; 95% CI: 0.60-1.07) after adjustment for the matching and other factors (income, energy intake, fruit intake, cigarette smoking, and alcohol intake). The inverse association was more pronounced for oral cavity and oropharyngeal tumors, for African Americans, and for females, but CIs were wide. To further investigate this potential risk reduction strategy for SCCHN, future studies should consider examining specific fish/shellfish, cooking practices, and other omega-3 fatty acid sources.

Self-renewing Monolayer of Primary Colonic or Rectal Epithelial Cells

BACKGROUND & AIMS

Three-dimensional organoid culture has fundamentally changed the in vitro study of intestinal biology enabling novel assays; however, its use is limited because of an inaccessible luminal compartment and challenges to data gathering in a three-dimensional hydrogel matrix. Long-lived, self-renewing 2-dimensional (2-D) tissue cultured from primary colon cells has not been accomplished.

METHODS

The surface matrix and chemical factors that sustain 2-D mouse colonic and human rectal epithelial cell monolayers with cell repertoires comparable to that in vivo were identified.

RESULTS

The monolayers formed organoids or colonoids when placed in standard Matrigel culture. As with the colonoids, the monolayers exhibited compartmentalization of proliferative and differentiated cells, with proliferative cells located near the peripheral edges of growing monolayers and differentiated cells predominated in the central regions. Screening of 77 dietary compounds and metabolites revealed altered proliferation or differentiation of the murine colonic epithelium. When exposed to a subset of the compound library, murine organoids exhibited similar responses to that of the monolayer but with differences that were likely attributable to the inaccessible organoid lumen. The response of the human primary epithelium to a compound subset was distinct from that of both the murine primary epithelium and human tumor cells.

CONCLUSIONS

This study demonstrates that a self-renewing 2-D murine and human monolayer derived from primary cells can serve as a physiologically relevant assay system for study of stem cell renewal and differentiation and for compound screening. The platform holds transformative potential for personalized and precision medicine and can be applied to emerging areas of disease modeling and microbiome studies.

Rutin inhibits proliferation, attenuates superoxide production and decreases adhesion and migration of human cancerous cells

Lung and colorectal cancer are the principal causes of death in the world. Rutin, an active flavonoid compound, is known for possessing a wide range of biological activities. In this study, we examined the effect of rutin on the viability, superoxide anion production, adhesion and migration of human lung (A549) and colon (HT29 and Caco-2) cancer cell lines. In order to control the harmlessness of the tested concentrations of rutin, the viability of cancer cell lines was assessed using a 3-(4,5-dimethylthiazol- 2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay. ROS generation was measured by lucigenin chemiluminescence detecting superoxide ions. To investigate the effect of rutin on the behavior of human lung and colon cancer cell lines, we performed adhesion assays, using various purified extracellular matrix (ECM) proteins. Finally, in vitro cell migration assays were explored using modified Boyden chambers. The viability of cancerous cells was inhibited by rutin. It also significantly attenuated the superoxide production in HT29 cells. In addition, rutin affected adhesion and migration of A549 and HT29 cell. These findings indicate that rutin, a natural molecule, might have potential as anticancer agent against lung and colorectal carcinogenesis.

Hepatic transcriptome implications for palm fruit juice deterrence of type 2 diabetes mellitus in young male Nile rats

Background

The Nile rat (NR, Arvicanthis niloticus) is a model of carbohydrate-induced type 2 diabetes mellitus (T2DM) and the metabolic syndrome. A previous study found that palm fruit juice (PFJ) delayed or prevented diabetes and in some cases even reversed its early stages in young NRs. However, the molecular mechanisms by which PFJ exerts these anti-diabetic effects are unknown. In this study, the transcriptomic effects of PFJ were studied in young male NRs, using microarray gene expression analysis.

Methods

Three-week-old weanling NRs were fed either a high-carbohydrate diet (%En from carbohydrate/fat/protein = 70:10:20, 16.7 kJ/g; n = 8) or the same high-carbohydrate diet supplemented with PFJ (415 ml of 13,000-ppm gallic acid equivalent (GAE) for a final concentration of 5.4 g GAE per kg diet or 2.7 g per 2000 kcal; n = 8). Livers were obtained from these NRs for microarray gene expression analysis using Illumina MouseRef-8 Version 2 Expression BeadChips. Microarray data were analysed along with the physiological parameters of diabetes.

Results

Compared to the control group, 71 genes were up-regulated while 108 were down-regulated in the group supplemented with PFJ. Among hepatic genes up-regulated were apolipoproteins related to high-density lipoproteins (HDL) and genes involved in hepatic detoxification, while those down-regulated were related to insulin signalling and fibrosis.

Conclusion

The results obtained suggest that the anti-diabetic effects of PFJ may be due to mechanisms other than an increase in insulin secretion.

Gallic acid induced apoptotic events in HCT-15 colon cancer cells

AIM: To investigate the inhibitory action of diet-derived phenolic compound gallic acid (GA) against HCT-15 colon cancer cells.

METHODS: The antiproliferative effect of GA against colon cancer cells was determined by performing thiazolyl blue tetrazolium bromide (MTT) assay. The colony forming ability of GA treated colon cancer cells was evaluated using the colony forming assay. The cell cycle changes induced by GA in HCT-15 cells were analyzed by propidium iodide staining. Levels of reactive oxygen species (ROS) and mitochondrial membrane potential of HCT-15 exposed to GA was assessed using 2’,7’-dichlorfluorescein-diacetate and rhodamine-123 respectively, with the help of flow cytometry. Morphological changes caused by GA treatment in the colon cancer cells were identified by scanning electron microscope and photomicrograph examination. Apoptosis was confirmed using flow cytometric analysis of GA treated HCT-15 cells after staining with Yo-Pro-1.

RESULTS: MTT assay results illustrated that GA has an inhibitory effect on HCT-15 cells with IC₅₀ value of 740 μmol/L. A time-dependent inhibition of colony formation was evident with GA treatment. Cell cycle arrest was evident from the accumulation of GA treated HCT-15 cells at sub-G1 phase (0.98 ± 1.03 vs 58.01 ± 2.05) with increasing exposure time. Flow cytometric analysis of GA treated HCT-15 cells depicted early events associated with apoptosis like lipid layer breakage and fall in mitochondrial membrane potential apart from an increase in the generation of ROS which were in a time dependent manner. SEM and photomicrograph images of the GA-treated cells displayed membrane blebbing and cell shrinking characteristics of apoptosis. Further apoptosis confirmation by Yo-Pro-1 staining also showed the time-dependent increase of apoptotic cells after treatment.

CONCLUSION: These results show that GA induced ROS dependent apoptosis and inhibited the growth of colon cancer cells.

Role of fish oil in human health and possible mechanism to reduce the inflammation

The roles of Omega-3 FAs are inflammation antagonists, while Omega-6 FAs are precursors for inflammation. The plant form of Omega-3 FAs is the short-chain α-linolenic acid, and the marine forms are the long-chain fatty acids: docosahexaenoic acid and eicosapentaenoic acid. Omega-3 FAs have unlimited usages, and they are considered as omnipotent since they may benefit heart health, improve brain function, reduce cancer risks and improve people's moods. Omega-3 FAs also have several important biological effects on a range of cellular functions that may decrease the onset of heart diseases and reduce mortality among patients with coronary heart disease, possibly by stabilizing the heart's rhythm and by reducing blood clotting. Some review studies have described the beneficial roles of Omega-3 FAs in cardiovascular diseases (CVDs), cancer, diabetes, and other conditions, including inflammation. Studies of the effect of Omega-3 FAs gathered from studies in diseased and healthy population. CVDs including atherosclerosis, coronary heart diseases, hypertension, and metabolic syndrome were the major fields of investigation. In studies of obesity, as the central obesity increased, the level of adipocyte synthesis of pro-inflammatory cytokines like tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6) were increased and the level of anti-inflammatory adiponectin was decreased indicating a state of inflammation. The level of C reactive protein (CRP) synthesized from hepatocyte is increased by the influence of IL-6. CRP can be considered as a marker of systemic inflammation associated with increased risks of CVDs. In molecular studies, Omega-3 FAs have direct effects on reducing the inflammatory state by reducing IL-6, TNF-α, CRP and many other factors. While the appropriate dosage along with the administrative duration is not known, the scientific evidence-based recommendations for daily intake are not modified.

Effect of omega-3 fatty acid supplementation on cancer incidence, non-vascular death, and total mortality: a meta-analysis of randomized controlled trials

Background

Omega-3 fatty acids are known to prevent cardiac death. However, previous observational studies have suggested that omega-3 fatty acids are associated with cancer risk in adults. We conducted a meta-analysis based on randomized controlled trials to evaluate the effect of omega-3 fatty acids on the risk of cancer incidence, nonvascular death, and total mortality.

Methods

In February 2013, we performed electronic searches in PubMed, EmBase, and the Cochrane Library to identify randomized controlled trials on cancer incidence, nonvascular death, and total mortality. Relative risk (RR) was used to measure the effect of omega-3 fatty acid supplementation on the risk of cancer incidence, nonvascular death, and total mortality using a random-effect model. The analysis was further stratified by factors that could affect the treatment effects.

Results

Of the 8,746 identified articles, we included 19 trials reporting data on 68,954 individuals. These studies reported 1,039 events of cancer, 2,439 events of nonvascular death, and 7,025 events of total mortality. Omega-3 fatty acid supplementation had no effect on cancer incidence (RR, 1.10; 95% CI: 0.97–1.24; P = 0.12), nonvascular death (RR, 1.00; 95% CI: 0.93–1.08; P = 1.00), or total mortality (RR, 0.95; 95% CI: 0.88–1.03; P = 0.24) when compared to a placebo. Subgroup analysis indicated that omega-3 fatty acid supplementation was associated with a reduction in total mortality risk if the proportion of men in the study population was more than 80%, or participants received alpha-linolenic acid.

Conclusions

Omega-3 fatty acid supplementation does not have an effect on cancer incidence, nonvascular death, or total mortality.

Events associated with apoptotic effect of p-Coumaric acid in HCT-15 colon cancer cells

AIM: To investigate the events associated with the apoptotic effect of p-Coumaric acid, one of the phenolic components of honey, in human colorectal carcinoma (HCT-15) cells.

METHODS: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tertazolium-bromide assay was performed to determine the antiproliferative effect of p-Coumaric acid against colon cancer cells. Colony forming assay was conducted to quantify the colony inhibition in HCT 15 and HT 29 colon cancer cells after p-Coumaric acid treatment. Propidium Iodide staining of the HCT 15 cells using flow cytometry was done to study the changes in the cell cycle of treated cells. Identification of apoptosis was done using scanning electron microscope and photomicrograph evaluation of HCT 15 cells after exposing to p-Coumaric acid. Levels of reactive oxygen species (ROS) of HCT 15 cells exposed to p-Coumaric acid was evaluated using 2’, 7’-dichlorfluorescein-diacetate. Mitochondrial membrane potential of HCT-15 was assessed using rhodamine-123 with the help of flow cytometry. Lipid layer breaks associated with p-Coumaric acid treatment was quantified using the dye merocyanine 540. Apoptosis was confirmed and quantified using flow cytometric analysis of HCT 15 cells subjected to p-Coumaric acid treatment after staining with YO-PRO-1.

RESULTS: Antiproliferative test showed p-Coumaric acid has an inhibitory effect on HCT 15 and HT 29 cells with an IC₅₀ (concentration for 50% inhibition) value of 1400 and 1600 μmol/L respectively. Colony forming assay revealed the time-dependent inhibition of HCT 15 and HT 29 cells subjected to p-Coumaric acid treatment. Propidium iodide staining of treated HCT 15 cells showed increasing accumulation of apoptotic cells (37.45 ± 1.98 vs 1.07 ± 1.01) at sub-G₁ phase of the cell cycle after p-Coumaric acid treatment. HCT-15 cells observed with photomicrograph and scanning electron microscope showed the signs of apoptosis like blebbing and shrinkage after p-Coumaric acid exposure. Evaluation of the lipid layer showed increasing lipid layer breaks was associated with the growth inhibition of p-Coumaric acid. A fall in mitochondrial membrane potential and increasing ROS generation was observed in the p-Coumaric acid treated cells. Further apoptosis evaluated by YO-PRO-1 staining also showed the time-dependent increase of apoptotic cells after treatment.

CONCLUSION: These results depicted that p-Coumaric acid inhibited the growth of colon cancer cells by inducing apoptosis through ROS-mitochondrial pathway.

A novel polypeptide from Meretrix meretrix Linnaeus inhibits the growth of human lung adenocarcinoma

A novel polypeptide (Mere15) was purified from Meretrix meretrix Linnaeus by ammonium sulfate fractionation, ion exchange, gel filtration and reversed phase chromatography. Mere15 exhibited selective cytotoxicity to several human cancer cells. In vivo study showed that Mere15 significantly suppressed the growth of human lung adenocarcinoma A549 xenograft in nude mice. The mechanism was associated with a G2/M phase arrest followed by apoptosis, including membrane blebbing, loss of mitochondrial membrane potential, externalization of phosphatidylserine, chromosome condensation and DNA fragmentation. Western blot analysis showed that the intrinsic pathway was involved in Mere15-induced apoptosis. These results suggest that Mere15 may have therapeutic potential for the treatment of non-small-cell lung carcinoma.

Chemopreventive effect of dietary polyphenols in colorectal cancer cell lines

Colorectal cancer (CRC) is the second most fatal and the third most diagnosed type of cancer worldwide. Despite having multifactorial causes, most CRC cases are mainly determined by dietary factors. In recent years, a large number of studies have attributed a protective effect to polyphenols and foods containing these compounds (fruits and vegetables) against CRC. Indeed, polyphenols have been reported to interfere with cancer initiation, promotion, and progression, acting as chemopreventive agents. The aim of this review is to summarize the main chemopreventive properties of some polyphenols (quercetin, rutin, myricetin, chrysin, epigallocatechin-3-gallate, epicatechin, catechin, resveratrol, and xanthohumol) against CRC, observed in cell culture models. From the data reviewed in this article, it can be concluded that these compounds inhibit cell growth, by inducing cell cycle arrest and/or apoptosis; inhibit proliferation, angiogenesis, and/or metastasis; and exhibit anti-inflammatory and/or antioxidant effects. In turn, these effects involve multiple molecular and biochemical mechanisms of action, which are still not completely characterized. Thus, caution is mandatory when attempting to extrapolate the observations obtained in CRC cell line studies to humans.

Dietary-induced ERbeta upregulation counteracts intestinal neoplasia development in intact male ApcMin/+ mice

Most sporadic colorectal cancers (CRCs) develop through the adenoma-carcinoma sequence pathway and are initiated by adenomatous polyposis coli (APC) gene mutations. Estrogen receptor beta (ERbeta) is recognized to progressively reduce its expression in adenomatous and carcinomatous tissues in humans. Moreover, ERbeta deficiency enhances small intestinal tumorigenesis in rodents. In the Apc(Min/+) mouse model, we evaluated intestinal polyp development and ERbeta expression plus other biological parameters influencing tumor growth (epithelial cell proliferation, apoptosis and migration) following the addition of a combination of the ERbeta-selective agonist silymarin (SIL) and/or lignin (LIG) to a high-fat/low-fiber diet. Forty-five Apc(Min/+) mice were divided in four groups: animals fed on the tumorigenic high-fat/low-fiber diet, the tumorigenic diet supplemented with SIL (0.02%) or purified LIG (6.24%) or SIL (0.005%) + LIG (6.24%). In these animals, we assessed polyp number and volume and their degree of dysplasia together with ERbeta messenger RNA (mRNA) and protein levels and epithelial cell proliferation, migration and apoptosis. The latter group of parameters was evaluated in normal and adenomatous mucosa and the results compared with those found in wild-type (WT) mice fed on the control diet. The addition of SIL or LIG to the diet and even more the specific combination of the two significantly counteracted intestinal tumorigenesis and increased ERbeta mRNA and protein levels. Cell proliferation and apoptosis were rebalanced and cell migration accelerated, restoring values similar to those observed in WT animals. Our results further support a protective effect of ERbeta in CRC suggesting the use of the combination of SIL-LIG as a potential approach against CRC development.

Apoptosis in the colonic crypt, colorectal adenomata, and manipulation by chemoprevention

This review discusses the biology and the methods of assessment of apoptosis, of which, the monoclonal antibody M30 would seem to be the most useful; the role of apoptosis in the etiology of colorectal cancer; and its use as a marker to monitor the beneficial effects of chemopreventative interventions to reduce the development of colorectal cancer within the context of clinical trials.

Bioactivity of Grape Chemicals for Human Health

Grapevine ( Vitis vinifera) products, grape and grape juice, represent a valuable source of bioactive phytochemicals, synthesized by three secondary metabolic pathways (phenylpropanoid, isoprenoid and alkaloid biosynthetic routes) and stored in different plant tissues. In the last decades, compelling evidence suggested that regular consumption of these products may contribute to reducing the incidence of chronic illnesses, such as cancer, cardiovascular diseases, ischemic stroke, neurodegenerative disorders and aging, in a context of the Mediterranean dietary tradition. The health benefits arising from grape product intake can be ascribed to the potpourri of biologically active chemicals occurring in grapes. Among them, the recently discovered presence of melatonin adds a new element to the already complex grape chemistry. Melatonin, and its possible synergistic action with the great variety of polyphenols, contributes to further explaining the observed health benefits associated with regular grape product consumption.

Thieno[2,3-c]isoquinolin-5-one, a potent poly(ADP-ribose) polymerase inhibitor, promotes atherosclerotic plaque regression in high-fat diet-fed apolipoprotein E-deficient mice: effects on inflammatory markers and lipid content

We recently showed that poly(ADP-ribose) polymerase (PARP) is activated within atherosclerotic plaques in an animal model of atherosclerosis. Pharmacological inhibition of PARP or reduced expression in heterozygous animals interferes with atherogenesis and may promote factors of plaque stability, possibly reflecting changes in inflammatory and cellular factors consistent with plaque stability. The current study addresses the hypothesis that pharmacological inhibition of PARP promotes atherosclerotic plaque regression. Using a high-fat diet-induced atherosclerosis apolipoprotein E(-/-) mouse model, we demonstrate that administration of the potent PARP inhibitor, thieno[2,3-c]isoquinolin-5-one (TIQ-A), when combined with a regular diet regimen during treatment, induced regression of established plaques. Plaque regression was associated with a reduction in total cholesterol and low-density lipoproteins. Furthermore, plaques of TIQ-A-treated mice were highly enriched with collagen and smooth muscle cells, displayed thick fibrous caps, and exhibited a marked reduction in CD68-positive macrophage recruitment and associated foam cell presence. These changes correlated with a significant decrease in expression of monocyte chemoattractant protein-1 and intercellular cell adhesion molecule-1, potentially as a result of a robust reduction in tumor necrosis factor expression. The PARP inhibitor appeared to affect cholesterol metabolism by affecting acyl-coenzymeA/cholesterol acyltransferase-1 expression but exerted no effect on cholesterol influx or efflux as assessed by an examination of the ATP-binding cassette transporter-1 and the scavenger receptor-A expression levels in the different experimental groups. In accordance, PARP inhibition may prove beneficial not only in preventing atherogenesis but also in promoting regression of preexisting plaques.

Quercetin may suppress rat aberrant crypt foci formation by suppressing inflammatory mediators that influence proliferation and apoptosis

The flavonoid quercetin suppresses cell proliferation and enhances apoptosis in vitro. In this study, we determined whether quercetin protects against colon cancer by regulating the protein level of phosphatidylinositol 3-kinase (PI 3-kinase) and Akt or by suppressing the expression of proinflammatory mediators [cyclooxygenase (COX)-1, COX-2, inducible nitric oxide synthase (iNOS)] during the aberrant crypt (AC) stage. Forty male rats were randomly assigned to receive diets containing quercetin (0 or 4.5 g/kg) and injected subcutaneously with saline or azoxymethane (AOM; 2 times during wk 3 and 4). The colon was resected 4 wk after the last AOM injection and samples were used to determine high multiplicity AC foci (HMACF; foci with >4 AC) number, colonocyte proliferation and apoptosis by immunohistochemistry, expression of PI 3-kinase (p85 and p85alpha subunits) and Akt by immunoblotting, and COX-1, COX-2, and iNOS expression by real time RT-PCR. Quercetin-fed rats had fewer (P = 0.033) HMACF. Relative to the control diet, quercetin lowered the proliferative index (P = 0.035) regardless of treatment and diminished the AOM-induced elevation in crypt column cell number (P = 0.044) and expansion of the proliferative zone (P = 0.021). The proportion of apoptotic colonocytes in AOM-injected rats increased with quercetin treatment (P = 0.014). Levels of p85 and p85alpha subunits of PI 3-kinase and total Akt were unaffected by dietary quercetin. However, quercetin tended to suppress (P < 0.06) the expression of COX-1 and COX-2. Expression of iNOS was elevated by AOM injection (P = 0.0001). In conclusion, quercetin suppresses the formation of early preneoplastic lesions in colon carcinogenesis, which occurred in concert with reductions in proliferation and increases in apoptosis. It is possible the effects on proliferation and apoptosis resulted from the tendency for quercetin to suppress the expression of proinflammatory mediators.

Factors affecting the conversion of apple polyphenols to phenolic acids and fruit matrix to short-chain fatty acids by human faecal microbiota in vitro

Proanthocyanidins (PAs) in apples are condensed tannins comprised mostly of (-)-epicatechin units with some terminal (+)-catechins. PAs, especially those having a long chain-length, are absorbed in the upper intestine only to a small extent and are passed to the colon. In the colon they are subjected to microbial metabolism by colonic microbiota. In the present article, the ability of human microbiota to ferment apple PAs is studied. Freeze-dried fruit preparations (apple, enzymatically digested apple, isolated cell-walls, isolated PAs or ciders) from two varieties, Marie Ménard and Avrolles, containing PAs of different chain lengths, were compared. Fermentation studies were performed in an in vitro colon model using human faecal microbiota as an inoculum. The maximal extent of conversion to known microbial metabolites, was observed at late time point for Marie Ménard cider, having short PAs. In this case, the initial dose also contributed to the extent of conversion. Long-chain PAs were able to inhibit the in vitro microbial metabolism of PAs shown as low maxima at early time points. Presence of isolated PAs also suppressed SCFA formation from carbohydrates as compared with that from apple cell wall or faecal suspension without substrates. The low maximal extents at early time points suggest that there is a competition between the inhibitory effect of the PAs on microbial activity, and the ability to convert PAs by the microbiota.

Increased induction of apoptosis by Propionibacterium freudenreichii TL133 in colonic mucosal crypts of human microbiota-associated rats treated with 1,2-dimethylhydrazine

Propionibacterium freudenreichii, a food-grade bacterium able to kill colon cancer cell lines in vitro by apoptosis, may exert an anticarcinogenic effect in vivo. To assess this hypothesis, we administered daily 2 x 10(10) colony-forming units (CFU) of P. freudenreichii TL133 to human microbiota-associated (HMA) rats for 18 d. Either saline or 1,2-dimethylhydrazine (DMH) was also administered on days 13 and 17 and rats were killed on day 19. The levels of apoptosis and proliferation in the mid and distal colon were assessed by terminal deoxynucleotide transferase-mediated deoxyuridine triphosphate nick end labelling (TUNEL) and proliferating cell nuclear antigen (PCNA) immunolabelling, respectively. The administration of P. freudenreichii TL133 significantly increased the number of apoptotic cells in DMH-treated rats compared to those given DMH only (P < 0.01). Furthermore, propionibacteria were able to decrease the proliferation index in the distal colon after treatment with DMH (P < 0.01). Conversely, propionibacteria alone did not exert such an effect on healthy colonic mucosa. P. freudenreichii TL133 thus facilitated the elimination of damaged cells by apoptosis in the rat colon after genotoxic insult and may play a protective role against colon cancer.

Mechanisms of colorectal and lung cancer prevention by vegetables: a genomic approach

Colorectal cancer (CRC) and lung cancer (LC) occur at high incidence, and both can be effectively prevented by dietary vegetable consumption. This makes these two types of cancer highly suitable for elucidating the underlying molecular mechanisms of cancer chemoprevention. Numerous studies have shown that vegetables exert their beneficial effects through various different mechanisms, but effects on the genome level remain mostly unclear. This review evaluates current knowledge on the mechanisms of CRC and LC prevention by vegetables, thereby focusing on the modulation of gene and protein expressions. The majority of the effects found in the colon are changes in the expression of genes and proteins involved in apoptosis, cell cycle, cell proliferation and intracellular defense, in favor of reduced CRC risk. Furthermore, vegetables and vegetable components changed the expression of many more genes and proteins involved in other pathways for which biologic meaning is less clear. The number of studies investigating gene and protein expression changes in the lungs is limited to only a few in vitro and animal studies. Data from these studies show that mostly genes involved in biotransformation, apoptosis and cell cycle regulation are affected. In both colon and lungs, genomewide analyses of gene and protein expression changes by new genomics and proteomics technologies, as well as the investigation of whole vegetables, are few in number. Further studies applying these 'omics' approaches are needed to provide more insights on affected genetic/biologic pathways and, thus, in molecular mechanisms by which different chemopreventive compounds can protect against carcinogenesis. Particularly studies with combinations of phytochemicals and whole vegetables are needed to establish gene expression changes in the colon, but especially in the lungs.

Butyrate-induced apoptosis and cell cycle arrest in bovine kidney epithelial cells: involvement of caspase and proteasome pathways

Beyond their nutritional effect, short-chain fatty acids, especially butyrate, modulate cell differentiation, proliferation, motility, and in particular, they induce cell cycle arrest and apoptosis. A bovine kidney epithelial cell line (Madin-Darby bovine kidney; MDBK) was used to investigate the cell cycle regulatory and apoptotic effects of butyrate. Butyrate not only induced apoptosis but also induced cell cycle arrest at the G1/S boundary and M/G2 in MDBK cells (P < 0.01). The cell responses were concentration-dependent (r(2) = 0.9482, P <0.001). In examining possible mechanisms for the apoptosis and cell cycle arrest induced by butyrate, the results showed that butyrate treatment activates caspase-3 activities and induces accumulation of acetylated histone. At least two proteins, cdc6 and cdk1, become targeted for destruction on butyrate treatment. These two proteins are downregulated (P < 0.01 and P < 0.05, respectively) by proteolytic pathways. Moreover, the proteasome inhibitor MG-132 (carbobenzoxy-L-leucyl-L-leucyl-L-leucinal) reverses the cell cycle arrest induced by butyrate, indicating a multiprotein crosstalk wherein the ubiquitination/ proteasome pathway interacted with the caspase-signaling pathway. Because the proteasome inhibitor MG-132 blocked activation of caspase-3, these results functionally locate the proteasome pathway upstream of the caspase pathway. All these results indicate that butyrate functions as both a nutrient and signaling molecule regulating cell growth and proliferation.

The profile of antioxidant systems and lipid peroxidation across the crypt-villus axis in rat intestine

The distribution of lipid peroxiation and profile of antioxidant-pro-oxidant enzyme systems have been studied in rat intestinal enterocyte across the length of villi. The MDA levels estimated as a measure of lipid peroxidation, under induced or uninduced in vitro conditions, indicated markedly high levels at villus tip cells compared to that in the crypt base. The activities of glutathione-S-transferase and glutathione reductase were three- to sixfold higher in villus tip cells compared to that in the crypt base. However the levels of catalase and superoxide dismutase showed a reverse pattern, being high in the crypt base and lowest in the villus tip region. Feeding coconut oil, sunflower oil, or groundnut oil did not modify the distribution pattern of these systems across crypt-villus unit in rat intestine. These findings suggest that the large amount of free radicals generated in villus tip cells may be responsible for the release of enterocytes from the villus tip as a consequence of apoptosis.

Review article: nutrition, obesity and colorectal cancer

BACKGROUND

The age-adjusted incidence of colorectal cancer is higher in prosperous industrialized countries than elsewhere. Dietary factors may account for 75% of sporadic colorectal cancer in the west, but the mechanisms remain obscure.

AIM

To review evidence for the effects of overweight and obesity, physical activity and specific dietary components on colorectal neoplasia.

METHODS

English language papers cited on MEDLINE, obtained using search terms related to colorectal cancer, physical activity and body mass and specific food components were reviewed.

RESULTS

There is evidence for adverse effects of overweight and obesity and protective effects of high physical activity against colon, but not for rectal cancer. These effects may reflect metabolic stress and chronic low-grade inflammation. There are also modest adverse effects of red and processed meat. There is evidence for protective effects of dietary fibre, but for fruits and vegetables the evidence remains weak and inconclusive. There is some evidence for protective effects of n-3 polyunsaturated fatty acids from fish, some micronutrients and possibly phytochemicals. The effects of many dietary constituents may depend upon genetic polymorphisms affecting a variety of genes.

CONCLUSION

Further research should focus particularly on the effects of insulin-resistance, impaired glucose tolerance and chronic low-grade inflammation on the colonic mucosa.

Eicosapentaenoic acid (EPA) reduces crypt cell proliferation and increases apoptosis in normal colonic mucosa in subjects with a history of colorectal adenomas

BACKGROUND AND AIMS

Omega-3 fatty acids in fish oil exert a protective effect on the development of colorectal cancer in animal models. Patients with colorectal adenomas have been shown to have increased crypt cell proliferation and decreased apoptosis in macroscopically normal appearing colonic mucosa. We investigated whether dietary supplementation with eicosapentaenoic acid (EPA) could alter crypt cell proliferation and apoptosis in such patients.

PATIENTS/METHODS

Thirty subjects were randomised to either 3 months of highly purified EPA in free fatty acid form (2 g/day) or to no treatment. Colonic biopsies were taken at the initial colonoscopy and repeated 3 months later, and analysed for cell proliferation and apoptosis (immunohistochemistry) and mucosal fatty acid content.

RESULTS/FINDINGS

Crypt cell proliferation was significantly reduced whilst apoptosis was significantly increased after EPA supplementation. Neither crypt cell proliferation nor apoptosis were altered in the control group. EPA in the mucosa increased significantly after EPA supplementation, whereas there was no significant change in controls.

CONCLUSIONS

Dietary supplementation with EPA significantly increases levels of this fatty acid in colonic mucosa, associated with significantly reduced proliferation and increased mucosal apoptosis. Further studies are needed to assess the potential efficacy of EPA supplementation in preventing polyps in the chemoprevention of colorectal cancer.

Effects of dietary flavonoids on apoptotic pathways related to cancer chemoprevention

Epidemiological studies have described the beneficial effects of dietary polyphenols (flavonoids) on the reduction of the risk of chronic diseases, including cancer. Moreover, it has been shown that flavonoids, such as quercetin in apples, epigallocatechin-3-gallate in green tea and genistein in soya, induce apoptosis. This programmed cell death plays a critical role in physiological functions, but there is underlying dysregulation of apoptosis in numerous pathological situations such as Parkinson's disease, Alzheimer's disease and cancer. At the molecular level, flavonoids have been reported to modulate a number of key elements in cellular signal transduction pathways linked to the apoptotic process (caspases and bcl-2 genes), but that regulation and induction of apoptosis are unclear. The aim of this review is to provide insights into the molecular basis of the potential chemopreventive activities of representative flavonoids, with emphasis on their ability to control intracellular signaling cascades responsible for regulating apoptosis, a relevant target in cancer-preventive approach.

Identification and quantification of glucosinolates in sprouts derived from seeds of wild Eruca sativa L. (salad rocket) and Diplotaxis tenuifolia L. (wild rocket) from diverse geographical locations

The Brassicaceae rocket species Eruca sativa L. (salad rocket) and Diplotaxis tenuifolia L. (wild rocket) are consumed throughout the world in salads, predominantly the leaves but also the flowers and more recently the sprouts (seedlings). Ontogenic profiling of glucosinolates and flavonoids in plants derived from commercial seed of these species has previously been done, but no studies have been conducted to determine how geographical origin affects glucosinolate composition in rocket species. Seeds from wild E. sativa L. and D. tenuifolia L. from diverse regions of the world were obtained from gene banks and grown under controlled conditions. Sprouts were harvested when they would normally be harvested for consumption, and glucosinolates were extracted and profiled in these accessions. All of the sprouts from Italian E. sativa L. had consistently high total glucosinolate content, with only a few exceptions, and also the highest percentage contents of 4-mercaptobutylglucosinolate. In contrast, sprouts produced from Central and Eastern European seeds had a much higher percentage of 4-methylthiobutylglucosinolate. With a single exception, Tunisia, all sprouts produced from North African seeds had very high 4-methylthiobutylglucosinolate contents. The single sample from China had a high total glucosinolate content and glucosinolate profile that was very similar to the accessions from Uzbekistan and Pakistan. All of the D. tenuifolia L. sprouts had consistently high total glucosinolate contents, and a high percentage of this was 4-mercaptobutylglucosinolate. This glucosinolate variation in levels and profiles of the rockets can be used for genetic studies, selected breeding, and human intervention studies.

Gender-specific modulation of markers for premalignancy by nutritional soy and calcium in the mouse colon

Sporadic colorectal cancer develops as a multistep process during decades of latency. Multiple factors, in particular nutrition, influence progression. Both nutritional calcium and soy are known to reduce sporadic cancer incidence. Soy contains high levels of phytoestrogens. Among them genistein is recognized as an antioxidant and cell-cycle inhibitor. However, timing and length of consumption of genistein as well as gender- and colon site-specific activity may result in beneficial or detrimental effects. We therefore evaluated the effect in mice of a basic AIN76A diet containing 20% soy as main protein source fed for 1 or 2 generations. In another set of animals, normal calcium levels (0.5%) were replaced by low calcium (0.04%) with or without supplementation of genistein (0.04%). Expression of the vitamin D receptor, cyclooxygenase (COX)-2, proapoptotic Bak and antiapoptotic Bcl-2 protein, as well as estrogen receptor (ER)-alpha and ER-beta mRNA were evaluated. Results were identical whether soy was fed for 1 or 2 generations. Soy decreased Bak and increased COX-2 and ER-alpha expression site-specifically in female mice. Vitamin D receptor protein was reduced only in males. In animals fed 0.04% dietary calcium, COX-2 protein was increased mainly in females, but supplementation of genistein to the diet lowered COX-2 expression significantly in both genders. Our results suggest that genistein counteracts the induction of a marker of colonic premalignancy by low nutritional calcium in both genders. However, soy itself enhances COX-2 and reduces Bak, but only in females. This suggests detrimental activity of an unknown component of soy triggered by a high-estrogen background.

Pathway analysis identifies perturbation of genetic networks induced by butyrate in a bovine kidney epithelial cell line

Ruminant species have evolved to metabolize the short-chain volatile fatty acids (VFA), acetate, propionate, and butyrate, to fulfill up to 70% of their nutrient energy requirements. The inherent VFA dependence of ruminant cells was exploited to add a level of increased sensitivity to the study of the role of butyrate gene-response elements in regulatory biochemical pathways. Global gene expression profiles of the bovine kidney epithelial cells regulated by sodium butyrate were investigated with high-density oligonucleotide microarrays. The detailed mechanisms by which butyrate induces cell growth arrest and apoptosis were analyzed using the Ingenuity Pathways Knowledge Base. The functional category and pathway analyses of the microarray data revealed that four canonical pathways (Cell cycles: G2/M DNA damage checkpoint, and pyrimidine metabolism; G1/S checkpoint regulation and purine metabolism) were significantly perturbed. The biologically relevant networks and pathways of these genes were also identified. IGF2, TGFB1, TP53, E2F4, and CDC2 were established as being centered in these genomic networks. The present findings provide a basis for understanding the full range of the biological roles and the molecular mechanisms that butyrate may play in animal cell growth, proliferation, and energy metabolisms.

Intestinal overexpression of ZNF148 suppresses ApcMin/+ neoplasia

ZNF148 (ZBP-89, Zfp148) is a multifunctional transcription factor expressed at low levels in most tissues. When overexpressed in gastrointestinal cancer cell lines, ZNF148 inhibits cellular proliferation and induces apoptosis. We sought to determine whether intestinal ZNF148 overexpression would abrogate adenoma development in the ApcMin/+ mouse, i.e., whether ZNF148 is a tumor suppressor. The 13-kb villin promoter was spliced upstream of the ZNF148 cDNA to generate transgenic villin-ZNF148 (ZNF148TgVZ) mice. Intestinal mucosal ZNF148 expression was elevated in four of five ZNF148(TgVZ) lineages and correlated with increased caspase-3 expression and activation. In addition, DNA fragmentation was increased in ZNF148TgVZ mice relative to wild-type littermates. These results suggested that increased intestinal ZNF148 expression induces apoptosis. ZNF148TgVZ mice were crossed with ApcMin/+ mice to assess the biological significance of intestinal ZNF148 overexpression. The presence of the ZNF148TgVZ allele in ApcMin/+ mice correlated with reduced gastrointestinal bleeding at 5 weeks, a 50% reduction in adenoma burden at 20-22 weeks, and prolonged survival (median survival of 33.5 days vs. 21.5 days), relative to nontransgenic littermates. These data suggest that enhanced ZNF148 expression activates intestinal apoptosis and thereby mitigates disease burden in ApcMin/+ mice. They also suggest that ZNF148 is a therapeutic target to inhibit colon cancer development.

Butyrate induces profound changes in gene expression related to multiple signal pathways in bovine kidney epithelial cells

BACKGROUND

Global gene expression profiles of bovine kidney epithelial cells regulated by sodium butyrate were investigated with high-density oligonucleotide microarrays. The bovine microarray with 86,191 distinct 60mer oligonucleotides, each with 4 replicates, was designed and produced with Maskless Array Synthesizer technology. These oligonucleotides represent approximately 45,383 unique cattle sequences.

RESULTS

450 genes significantly regulated by butyrate with a median False Discovery Rate (FDR) = 0 % were identified. The majority of these genes were repressed by butyrate and associated with cell cycle control. The expression levels of 30 selected genes identified by the microarray were confirmed using real-time PCR. The results from real-time PCR positively correlated (R = 0.867) with the results from the microarray.

CONCLUSION

This study presented the genes related to multiple signal pathways such as cell cycle control and apoptosis. The profound changes in gene expression elucidate the molecular basis for the pleiotropic effects of butyrate on biological processes. These findings enable better recognition of the full range of beneficial roles butyrate may play during cattle energy metabolism, cell growth and proliferation, and possibly in fighting gastrointestinal pathogens.

ω-3 Polyunsaturated fatty acids and ionizing radiation: Combined cytotoxicity on human colorectal adenocarcinoma cells

OBJECTIVE

This study evaluated whether omega-3 polyunsaturated fatty acids (PUFAs) could enhance the radiosensitivity of three different human colorectal adenocarcinoma cell lines. To understand the underlying mechanisms, the effects of omega-3 PUFAs on the cell growth, survival, and apoptosis were evaluated alone or in combination with an antioxidant (vitamin E) and compared with the effects of omega-6 PUFAs.

METHODS

LS174T, CO112, and Caco-2 cell survival was assessed by clonogenic assay after a 3-d pretreatment with omega-3/omega-6 PUFAs and/or vitamin E before a single X-ray exposure to 4 Gy. Cell growth and viability were measured by double fluorescence-activated cell sorter analyses using propidium iodide and fluorescein isothiocyanate-conjugated annexin V. Student's t test or multivariable linear regression analyses were used for comparison.

RESULTS

Preincubation with 30 to 100 micromol/L of omega-3 PUFAs induced a dose-dependent additive decrease in cell survival after irradiation (P < 0.05). Evaluation of the underlying mechanisms indicated that omega-3 PUFAs mainly decreased the cell number via apoptosis induction. Moreover, formation of lipid peroxidation products and modulation of cyclooxygenase II activity seemed to be involved, because coincubation with 10 micromol/L vitamin E abolished the effect of 50 micromol/L of omega-3 PUFAs (P < 0.05), whereas omega-6 PUFAs could partly mimic omega-3 PUFA effects.

CONCLUSION

These observations suggest that omega-3 PUFAs may be potential candidates as nutritional adjuvants to enhance the efficacy of human colorectal cancer radiotherapy.

Cruciferous vegetables and colo-rectal cancer

Cruciferous vegetables have been studied extensively for their chemoprotective effects. Although they contain many bioactive compounds, the anti-carcinogenic actions of cruciferous vegetables are commonly attributed to their content of glucosinolates. Glucosinolates are relatively biologically inert but can be hydrolysed to a range of bioactive compounds such as isothiocyanates (ITC) and indoles by the plant-based enzyme myrosinase, or less efficiently by the colonic microflora. A number of mechanisms whereby ITC and indoles may protect against colo-rectal cancer have been identified. In experimental animals cruciferous vegetables have been shown to inhibit chemically-induced colon cancer. However, the results of recent epidemiological cohort studies have been inconsistent and this disparity may reflect a lack of sensitivity of such studies. Possible explanations for the failure of epidemiological studies to detect an effect include: assessment of cruciferous vegetable intake by methods that are subject to large measurement errors; the interaction between diet and genotype has not been considered: the effect that post-harvest treatments may have on biological effects of cruciferous vegetables has not been taken into account.

Differential effects of ferulic acid and p-coumaric acid on S phase distribution and length of S phase in the human colonic cell line Caco-2

Ferulic acid (FA) and para-coumaric acid (p-CA) may mediate the protective effects of whole-grain cereals against colon cancer. Therefore, the effects of FA and p-CA on the metabolic activity, proliferation, cell cycle phase distribution, and kinetics of the colonic endothelial tumor cell line Caco-2 was studied. Both compounds at 1500 microM decreased the number of cells to 43-75% of control after 2-3 days of treatment. Cell cycle phase distribution and cell cycle kinetics were determined by flow cytometric analysis after bromodeoxyuridine labeling. Each compound at 1500 microM decreased the proportion of cells in the G(1) phase and increased the proportion of cells in the S and G(2) phases. Treatment with 1500 microM FA significantly increased the length of the S phase, while p-CA did not. It was concluded that FA and p-CA inhibited cell proliferation by presumably affecting different cell cycle phases, and this warrants further investigations because this inhibition may be one explanation for the diet-related protection against cancer.

Vegetables affect the expression of genes involved in anticarcinogenic processes in the colonic mucosa of C57BL/6 female mice

There is abundant epidemiological evidence that vegetable consumption decreases colorectal cancer (CRC) risk. However, the molecular targets in the genome are mostly unknown. The present study investigated the effects of vegetable consumption on gene expression in the colon mucosa of female C57Bl/6 mice using cDNA microarray technology. Mice were fed one of 8 diets: a control diet containing no vegetables (diet 1); a diet containing 100 g/kg (diet 2, 10% dose), 200 g/kg (diet 3, 20% dose), or 400 g/kg (diet 4, 40% dose) of a vegetable mixture; or a diet containing 70 g/kg of cauliflower (diet 5, 7% dose), 73 g/kg of carrots (diet 6, 7.3% dose), 226 g/kg of peas (diet 7, 22.6% dose); or 31 g/kg of onions (diet 8, 3.1% dose). The vegetable mixture used in diets 2 to 4 consisted of the 4 individual vegetables used in diets 5 to 8: cauliflower (30% wet wt), carrots (30% wet wt), peas (30% wet wt), and onions (10% wet wt). To assess gene expression changes, colonic mucosal cells were collected after the mice were killed. Total RNA was isolated and microarray technology was used to measure the expression levels of 602 genes simultaneously. For 39 genes, significant dose-dependent effects were found, although in general the relations were not linear. For 15 genes, the altered expression could indeed explain reduced cancer risk at various stages of CRC development. Eleven genes were modulated by the vegetable mixture as well as by one or more of the individual vegetables. For 7 of the genes, the modulation by the mixture was due to the effect of a particular vegetable. These genes are of particular interest because they were consistently affected and could be involved in the prevention of CRC by vegetable consumption.

Suitability of a batch in vitro fermentation model using human faecal microbiota for prediction of conversion of flaxseed lignans to enterolactone with reference to an in vivo rat model

BACKGROUND

In vitro fermentation models have been used widely for studies of shortchain fatty acid (SCFA) formation from carbohydrates, whereas the suitability of these methods for enterolactone (ENL) formation has received less attention.

AIM

The aim was to study the suitability of an in vitro fermentation model for prediction of bioconversion of lignans to ENL, to compare the approach with that of an in vivo rat model and to study the SCFA formation in both models.

METHODS

Predigested samples of rye bran (R), flaxseed meal (F) alone, or in combination with rye bran (R&F) and a faecal control were incubated in an in vitro fermentation model using human faecal microbiota. In the in vivo experiment rats consumed a non-fibre control diet (C) or diets supplemented either with rye bran (R), flaxseed meal (F) alone, or with their combination (R&F) for four weeks. Enterodiol (END), ENL and SCFA concentrations were measured from in vitro faecal fermentation samples and from the intestinal contents of rats. Plasma ENL concentrations from rats were also measured.

RESULTS

The highest ENL production was found in vitro with the F supplement (areas under curve: 740 +/- 4, 7,500 +/- 400, 2,600 +/- 500 and 1,520 +/- 70 nmol x h for the R, F, R&F supplements and faecal control, respectively). In vivo, the concentration of ENL in caecal digesta from flaxseed meal was significantly (P < 0.05) enhanced by the presence of rye bran (medians 261, 407 and 24 nmol/g in the F, R&F and C groups, respectively). No correlation was found between the models regarding ENL production, possibly due to different responses to the presence of rye bran matrix, differences in microbiota or application of a batch in the in vitro fermentation model. Rye bran supplementation enhanced butyrate production both in vitro and in vivo.

CONCLUSION

In vitro fermentation and the in vivo rat models responded differently to the presence of rye bran and no correlation with regard to the ENL formation from flaxseed lignans was observed.

Effects of Flavonoids on Cell Proliferation and Caspase Activation in a Human Colonic Cell Line HT29: An SAR Study

A library of 42 natural and synthetic flavonoids has been screened for their effect on cell proliferation and apoptosis in a human colonic cell line (HT-29). Examples of different classes of flavonoids have been screened, and the effects of hydroxylation, methoxylation and/or C-alkylation at various positions in the A- and B-rings have been assessed. Flavones and flavonols possess greater antiproliferative activity than chalcones and flavanones. With respect to structural modification of flavonoids, C-isoprenylation was by far the most effective, with substitution at the 8-position and longer chains, such as geranyl giving the best results. Finally, most compounds that significantly reduced cell survival also increased caspase activity, suggesting that at least part of their antiproliferative activity might be attributable to an apoptotic response.

Inhibitory effects of Centella asiatica on azoxymethane-induced aberrant crypt focus formation and carcinogenesis in the intestines of F344 rats

Effects of the water extract of Centella asiatica Linn. on formation of azoxymethane (AOM)-induced aberrant crypt foci (ACF) and intestinal tumorigenesis in male F344 rats were investigated. Treatment with the extract significantly decreased the number of larger ACF (with four or more crypts per focus) in the large intestine in the early stage, while the number of methylated DNA adducts was not decreased compared with that in the AOM-treated group. In the post-initiation stage, the extract significantly decreased the total number of ACF and the number of larger ACF, accompanied by a decrease in the 5-bromo-2'-deoxyuridine-labeling index and an increase in the induction of apoptotic cells in the colonic mucosa. The incidences of neoplasms, the numbers of adenocarcinomas in the small intestines and entire intestines, and sizes of neoplasms in the entire intestines in rats fed C. asiatica extract at a dose of 10 mg/kg were smaller than those in rats given AOM alone (p < 0.05). The extract at a dose of 100 mg/kg significantly reduced the multiplicity of neoplasms in the small intestine (p < 0.05). These results suggest that inhibition of the formation of AOM-induced ACF by C. asiatica extract is associated with modification of cell proliferation and induction of apoptosis in colonic crypts and that the extract has a chemopreventive effect on colon tumorigenesis.

Dietary cancer and prevention using antimutagens

Many of the cancers common in the Western world, including colon, prostate and breast cancers, are thought to relate to dietary habits. Of the known risk factors, many will act through increasing the probability of mutation. Recognised dietary mutagens include cooked meat compounds, N-nitroso compounds and fungal toxins, while high meat and saturated fat consumption, increasing rates of obesity, and regular consumption of alcohol and tobacco are all dietary trends that could indirectly enhance the probability of mutation. However, there are significant difficulties in implementing and sustaining major dietary changes necessary to reduce the population's intake of dietary mutagens. Dietary antimutagens may provide a means of slowing progression toward cancer, and be more acceptable to the population. Consideration of genetic mechanisms in cancer development suggest several distinct targets for intervention. Strategies that reduce mutagen uptake may be the most simple intervention, and the one least likely to result in undesirable side effects. Certain (but not all) types of dietary fibres appear to reduce mutation through this mechanism, as may certain probiotics and large planar molecules such as chlorophyllin. Antioxidants have been suggested to scavenge free radicals, and prevent their interactions with cellular DNA. Small molecule dietary antioxidants include ascorbic acid, Vitamin E, glutathione, various polyphenols and carotenoids. We found a statistically significant relationship between colon cancer incidence and soil selenium status across different regions of New Zealand. Additionally, a study of middle-aged men suggested that blood selenium levels lower than 100 ng/ml were inadequate for repair or surveillance of oxidative (and other) DNA damage. We suggest that selenium will be an important antimutagen, at least in New Zealand, possibly through antioxidant effects associated with selenium's role in enzymes associated with endogenous repair of DNA damage. Modulation of xenobiotic metabolizing enzymes is well recognised as cancer-protective, and is a property of various flavonoids and a number of sulfur-containing compounds. Many fruits and vegetables contain compounds that will protect against mutation and cancer by several mechanisms. For example, kiwifruit has antioxidant effects and may also affect DNA repair enzymes. Dietary folate may be a key factor in maintenance of methylation status, while enhanced overall levels of vitamins and minerals may retard the development of genomic instability. The combination of each of these factors could provide a sustainable intervention that might usefully delay the development of cancer in New Zealand and other populations. Although there are a range of potentially antimutagenic fruits, vegetables and cereals available to these populations, current intake is generally below the level necessary to protect from dietary or endogenous mutagens. Dietary supplementation may provide an alternative approach.

n-3 Polyunsaturated fatty acids and colon cancer prevention

The incidence of colon cancer in industrialised countries has increased since the early 1970s. It is estimated that more than one-third of cases are associated with factors related to a Western diet. Both the type and amount of dietary fats consumed have been implicated in colon cancer aetiology. Recent studies have demonstrated that n-3 polyunsaturated fatty acids (PUFAs), commonly found in fish oil (FO), could prevent colon cancer development. Evidences show that n-3 PUFAs act at different stages of cancer development and through several mechanisms including the modulation of arachidonic acid-derived prostaglandin synthesis, and Ras protein and protein kinase C expression and activity. As a result, n-3 PUFAs limit tumour cell proliferation, increase apoptotic potential along the crypt axis, promote cell differentiation and possibly limit angiogenesis. The modulatory actions of n-3 PUFAs on the immune system and their anti-inflammatory effects might also play a role in reducing colon carcinogenesis. There remains, nevertheless, some ambiguity over the safety of n-3 PUFAs with respect to secondary tumour formation. However, it appears that n-3 PUFAs may be of use in colon cancer prevention.

Emerging diet-related surrogate end points for colorectal cancer: UK Food Standards Agency diet and colonic health workshop report

The UK Food Standards Agency convened a group of expert scientists to review current research investigating emerging diet-related surrogate end points for colorectal cancer (CRC). The workshop aimed to overview current research and establish priorities for future research. The workshop considered that the validation of current putative diet-related surrogate end points for CRC and the development of novel ones, particularly in the emerging fields of proteomics, genomics and epigenomics, should be a high priority for future research.